England and Wales High Court (Patents Court) Decisions

IN THE HIGH COURT OF JUSTICE
CHANCERY DIVISION
PATENTS COURT

		Royal Courts of Justice Rolls Building Fetter Lane, London, EC4A 1NL
		10/05/2013

Mr Justice Vos:

Introduction

1. The Claimant, Swarovski-Optik KG ("Swarovski"), contends that its patent number EP (UK) 1 746 451 (the "Patent") has been infringed by the Defendants (together "Leica") by the supply of a range of three zoom sighting telescopes (or zoom riflescopes) in its "Magnus" range known as the 1-6.3x24, the 1.5-10x42, and the 2.4-16x56 ("Leica's riflescopes"). In these formulations, as in other descriptions of riflescopes, the numbers before the "x" refer to the magnification range, and the number after the "x" refers to the diameter of the objective lens in millimetres. The figures before the "x" are referred to as the zoom range of the riflescope, and the second figure divided by the first gives the zoom factor or zoom ratio, such that Leica's three riflescopes have nominal zoom factors of 6.3, 6.67, and 6.67 respectively.
2. Swarovski's Patent relates to sighting telescopes or riflescopes with a zoom factor greater than 4, and is concerned with enabling a view of the surrounding area that is as large as possible across the entire range of magnification. It was suggested at some stages that the objective was to avoid a "tunnel effect" at low magnifications, though that term is not mentioned in the Patent, and I have ultimately concluded that the evidence concerned with it was of peripheral significance. The aims of the Patent are achieved by the use of an additional strong negative lens called an "optical beam deflector device" in the Patent so as to guarantee a subjective or apparent field of view of at least 22 degrees at all magnifications. In this judgment, I shall generally refer to this "optical beam deflector device" using the abbreviation "negative lens".
3. This action raises issues of validity and infringement, but the main issues arise in relation to validity. In short, Leica say that the Patent is invalid because its teaching was either obvious or not novel in the light of the common general knowledge and the prior art as at the priority date of 20^th July 2005. Though the experts' reports and some of the argument was technically complex, the ultimate issue on obviousness, which took up most time, was whether it would have been obvious in July 2005 to the skilled person to insert a strong negative lens some distance to the objective side of the second intermediate image (and within the inverting lens system) to achieve the objectives in the Patent (namely a zoom factor greater than 4 and a subjective field of view at all magnifications greater than 22 degrees).
4. The prior art relied upon by Leica was as follows:-

i) An IOR 2-12x32 riflescope designed and manufactured by IOR in Romania in about 2003-4 (the "IOR riflescope").

ii) A German textbook by Helmut Naumann with the translated title of "Optics Elements: pocketbook of technical optics" ("Naumann");

iii) Betensky's US Patent 5,500,769 of 19^th March 1996 ("Betensky");

iv) Mai's US Patent 5,671,088 of 23^rd September 1997 ("Mai"); and

v) Nikon's Japanese Patent 11326789 A of 26^th November 1999 ("Nikon").

5. There is parallel litigation in Germany, the European Patent Office ("EPO") and in Austria. The parties are agreed, however, that this case must nonetheless be determined on the evidence I have heard. The parallel proceedings are:-

i) German proceedings involving the German aspect of the European Patent as well as a utility patent model known as a "Gebrauchsmuster", providing similar protection for a more limited period and with less stringent patentability requirements.

ii) EPO pending proceedings, in which the Opposition Division recently rejected the claims as granted, but upheld an amended form of the claims (though the same amendments have not been advanced before me). The EPO's reasons were provided towards the end of the trial.

iii) An Austrian patent, from which the Patent claims priority, was held to be invalid in post-grant opposition proceedings on 27^th March 2009 in the light of the prior art in Mai and Betensky.

6. Before identifying and dealing with the issues that I have to decide and the evidence adduced, I shall set out a brief chronology of relevant events.

Chronology

7. On 12-15^th February 2004, the IOR riflescope was exhibited at the 2004 SHOT show in Las Vegas.
8. In February 2005, a quantity of IOR riflescopes (model 2-12x32/MP8/IL) were sold by IOR to Realex in Finland, and then re-sold by Realex to a Mr Juha Espo.
9. On 19^th May 2005, a magazine called "Guns & Ammo" published an article describing various riflescopes with zoom factors of 3x or 4x, but only the IOR riflescope with a higher zoom factor. The IOR riflescope was described as "quite an achievement".
10. 20^th July 2005 is the priority date under the Patent.
11. On 8^th April 2006, the application for the Patent as filed included in Claim 4 of the "Patent Claims" that "[t]he long-distance optical device according to any one of claims 1 to 3, characterized in that the inverting system (1) has at least two optical elements (3a, 3b), preferably lens arrangements, which can be moved relative to one another".
12. On 13^th May 2011, the Claim Form in these proceedings was issued.
13. On 6^th July 2012, Mr Christof Heintz of Carl Zeiss performed tests on another IOR riflescope model number 3-18x42.
14. In mid-March 2013, oral opposition proceedings took place before the Opposition Division of the EPO. The Patent was upheld in amended form, as I have already indicated. Leica intends to appeal.
15. On the second day of the trial before me, 12^th April 2013, Leica applied to re-amend its grounds of invalidity so as to rely upon a further IOR riflescope, model 9-36x56, not previously mentioned in these proceedings, by way of prior art. This IOR scope had also allegedly been exhibited at the SHOT show in Las Vegas in 2004 and had gone into commercial production later that year. The model 9-36x56 was not of the same family as the IOR riflescope (2-12x32), which had been previously relied upon. Having indicated a preliminary willingness to allow the amendment provided Swarovski could be given an opportunity to inspect an example of this new riflescope or the data concerning it, I ultimately decided to refuse it on the primary ground that such inspections were not possible in the time available without an adjournment of the trial, which Leica neither sought nor wanted. Consistently, I refused to allow Leica to rely on the larger part of Ms Dana Granciu's 2^nd witness statement concerning the IOR 9-36x56 riflescope.

Technical terms

16. The glossaries provided by the parties' experts are not significantly divergent. The Patent concerns a "telescope or sighting telescope" including an "inverting system". The main use of these telescopes is as riflescopes. They all include (i) an objective lens system facing the target (generally drawn in the diagrams to the left), (ii) an erecting lens system or relay system or inverting system to reverse the upside down first intermediate image produced by the objective lens system, and (iii) an eyepiece lens system to view the second intermediate image created by the erecting lens system.
17. Leica's expert, Professor Philip Rogers ("Professor Rogers"), produced the following diagram describing a typical arrangement. He described the two intermediate images as "inverted" and "erect". I prefer the terms "first intermediate image" and "second intermediate image", which I intend to use in this judgment.

18. In broad terms, the erecting lens system creates the zoom magnification. A smooth zoom requires two (or sometimes more) lenses in that system to move, but not always in the same direction. The movements are complex and are not the subject of this dispute, but broadly one lens moves regularly whilst the other moves closer to the first and then away from it. At higher magnifications the zoom lenses are closer to the objective lens system, and at lower magnifications the zoom lenses are generally closer to the eyepiece lens system.
19. A sighting telescope or riflescope contains cross-hairs or a reticle which enable the user to focus on the target. The reticle must be on or close to one of the intermediate images if it is to be in focus at the same time as the target itself. There are examples of riflescopes which have the reticle at each of the first and second intermediate image.
20. It was common ground that riflescopes required eye relief of between 80-90 millimetres. That means that this is the distance from the eyepiece to the user's eye. It is required to avoid the gun recoiling and causing injury to the user. Pistol scopes require much larger eye relief. Longer eye relief generally reduces the field of view.
21. Subjective or apparent field of view is the field of view seen by the user through the instrument. Outside world field of view is the extent of that image in the outside world. The subjective field of view is approximately the outside world field of view multiplied by the magnification of the telescope. Field of view is measured in degrees or as the notional length of an object viewed through a telescope at a particular distance.
22. Professor Rogers produced the following drawing to explain the concepts:-

23. There are a number of limitations on the subjective field of view, including the deterioration of the image at the edge (generally the tangential image, as opposed to the sagittal or radial image), and the use of a physical field stop, normally at one or both of the intermediate images, to cut off the image beyond a certain diameter. The deterioration of the image at the edge caused by dimming is also called 'vignetting'. The introduction of a field stop at the first intermediate image to reduce vignetting at low magnifications may cause a tunnel effect with a black ring appearing around the observed image.
24. One aspect of the subjective field of view that assumed great importance in this case was field curvature, such that even though the image may be sharply focussed, it will be formed over a curved surface, tending to curve away from the eye of the observer, as shown in the following diagram (again produced by Professor Rogers):-

25. Field curvature is generally worse at high magnifications and when only positive lenses are used in the system. There is then a high "Petzval Sum". A positive lens is a lens with at least one convex surface which has the effect of causing the beam to converge; positive lenses generally cause curvature away from the user. A negative lens is one with at least one convex surface that causes the beam to diverge; negative lenses generally cause curvature towards the user.
26. Field curvature can be reduced by using less powerful positive lenses (and therefore lowering the Petzval Sum), or ameliorated by overcorrecting for an off-axis aberration known as astigmatism. Using less powerful lenses would require the riflescope to be longer to achieve the same magnification. Field curvature would be most apparent at the lowest magnification of a zoom riflescope, and as the field of view increases, because field curvature increases with the square of the field of view. Professor Rogers introduced the somewhat controversial concept of "image curvature" as meaning the combination of curvature caused by Petzval field curvature and that caused by astigmatism; in reality, he meant what the eye actually sees in terms of field curvature, as opposed to the objectively assessed field curvature. I shall return to that concept in due course.

The Patent

27. The authentic text of the Patent is in German, but the parties have ultimately agreed a translation. The description in the Patent as granted was as follows. I set out the whole of it, because the parties have referred to each paragraph for one purpose or another:-

"[0001] This invention relates to a telescope or sighting telescope which are long-distance optical devices, with an inverting system and an adjustable optical magnification means with a more than fourfold magnification.

[0002] Document US 5,500,769 describes optical systems for binoculars with a magnification which can be varied with the aid of a displaceable field lens unit. To this end, the field lens unit moves from a position at the side of the objective lens unit of the intermediate image to a position at the side of the eye lens unit of the intermediate image, i.e. the field lens unit is moved through the intermediate image. Accordingly, such a movement leads to an increase in the magnification of the system, and the movement is able to increase the magnification of the system from approximately 7 to approximately 12. The adjustable optical magnification system - in this case the field lens unit - therefore causes a variation of the magnification by 1.7 times (ratio of the maximum to the minimum magnification of the complete system as a whole = 12/7), corresponding to a zoom factor of 1.7.

[0003] Document GB 690,278 discloses a viewfinder with a variable field of view for a camera or cine camera. The article "New Type of Large-Angle-Binocular-Microtelescopes" published in the Proceedings of the Society of Photo-Optical Instrumentation Engineers (SPIE, Volume 1527, Pages 413-418) discusses the design aspects of binoculars with Galilean telescopes, the purpose of which is to provide a large field of view. A sighting telescope with optics for adjusting the magnification is also known from document US 2,479,792 A. In this instance, the magnification of the telescope can be varied between 2.5 times and 4 times, corresponding to a zoom of 1.6 times. Document GB 303,787 describes a telescope and an inverting lens system for telescopes and the inverting lens system used enables a continuously variable total magnification between a fivefold and a tenfold magnification (zoom 2 times) to be obtained.

[0004] The optical system for an observation device described in document US 3,045,545 comprises, in addition to the objective lens and the eyepiece, a zoom system for continuously varying the magnification. The zoom system in this instance reproduces the intermediate image created in an objective lens-side image plane with a variable image scale into the eyepiece-side image plane, at the same time inverting the image and thus making it upright. The zoom system comprises two mutually displaceable lens systems. The described observation device further comprises a lens system referred to as a focuser and a field lens between the objective lens and the zoom system or inverting system. The magnification of the observation device can be varied across a range (zoom) of 4:1. In the case of the telescope disclosed in document US 3,918,791, an anastigmatic lens group is provided between the objective lens and the eyepiece besides a field lens which is displaceable in the direction of the optical axis in order to invert the image and vary the magnification.

[0005] When an object at a long distance is observed with the naked eye, its apparent angular size is small. The purpose of any long-range optical device is to magnify this small angle. The long-range optical device therefore ensures that the apparent angular size reaching the observer's eye is as large as possible. At the same time, it should also be possible to obtain a view of the surrounding area that is as large as possible.

[0006] With long-range optical devices of the generic type with adjustable magnification and zoom capability, enabling a view of the surrounding area that is as large as possible across the entire range of magnification is particularly critical.

[0007] The objective of the invention is to improve long-range optical devices of the generic type in this respect.

[0008] This is achieved by means of the invention on the basis of the characterising features of the telescope or sighting telescope defined in claim 1, comprising an optical beam deflector device which guarantees a subjective field of view [Translator's note: "subjective field of view" can also be translated as "apparent field of view" or "angular field of view" in the image space] of the telescopic device of at least 22°, preferably between 22° and 24°, at all magnifications, at least for light with a wavelength of approximately 550 nm.

[0009] As a result of the optical beam deflector device, it is now possible to provide a subjective field of view of at least 22° even at low magnifications, in particular at the lowest magnification, of the telescopic device. Until now, this has only been possible at the larger magnifications of generic telescopic devices. With the aid of the telescopic device proposed by the invention, even at low magnifications, the observer sees a larger part of the surrounding area than was possible using the prior art systems.

[0010] According to a further aspect of the invention, the set objective is also achieved if the beam deflector device ensures a total focal length of the inverting system of between 11 mm and 7 mm, preferably between 10 mm and 8 mm, at the maximum magnification.

[0011] Further details and features of the invention will be explained below with reference to the appended drawings. Of these:

Fig. 1 is a longitudinal section through a sighting telescope according to the prior art,

Figs. 2a to 2c each show a section through an inverting system according to the prior art,

Figs. 3a to 3c each show a section through an inverting system of an example embodiment of a sighting telescope proposed by the invention,

Fig. 4 is a schematic diagram illustrating the set-up needed for conducting measurements to determine the subjective field of view.

[0012] Fig. 1 is a schematic illustration showing a section through a sighting telescope according to the prior art. At the end facing the object during observation, it has a lens arrangement, referred to as the objective lens 4 below, and at the end facing the observer's eye, a lens arrangement that will be referred to as eyepiece 5. Disposed between the objective lens 4 and the eyepiece 5 is the central tube 6. It often provides a support for one or more adjusting turrets 8, by means of which various adjustment functions known from the prior art can be controlled. Disposed inside the central tube between the objective lens 4 and eyepiece 5 is the inverting system 1. This is known in the prior art as an optical system which is used to erect the image generated by the objective lens 4 in an upright position. The inverting system 1 is usually disposed between the objective lens-end image plane 9 and the eyepiece-end image plane 10. Not only is the inverting system 1 often used to provide an upright image, it is also used to magnify the intermediate image generated in the objective-end image plane 9. In the sighting telescope illustrated in Fig. 1, the optical magnification means is integrated in the inverting system 1. The optical magnification means and inverting system are therefore designed as a single component.

[0013] Two optical elements 3a and 3b are provided as a means of magnifying and erecting the image in an upright position. In general, achromatic lenses in the form of so-called cemented lenses are used for this purpose, in other words arrangements of lenses glued together, which are expediently designed to control chromatic aberration. In the case of the prior art and also in the inverting systems and telescopes or sighting telescopes proposed by the invention, they advantageously have refractive powers of + 20 dpt (dioptres) to + 53 dpt, preferably + 21 dpt to + 35 dpt, even more preferably in the range of between + 23 dpt and + 26 dpt. To enable the magnification of the illustrated sighting telescope to be varied, the optical elements 3a and 3b can be moved along control grooves. By sliding the optical elements 3a and 3b, the intermediate image projected by the objective lens 4 into the objective lens-end image plane 9 is reproduced with a varying image scale and positioned upright in the eyepiece-end image plane 10. The distance between the two planes 9 and 10 does not change when the optical elements 3a and 3b are moved in the embodiment illustrated as an example. Another option known from the prior art is to provide a field lens 11 as well. This helps to guide the beam emerging from an object point at the periphery of the field of view, and passing through the objective lens 4, through the narrow passage of the central tube 6 and the inverting system 1.

[0014] In the systems known from the prior art, the image scale is changed by moving the optical elements 3a and 3b along control grooves, not depicted in detail. Figs. 2a to 2c illustrate the positions of the optical elements 3a and 3b at different magnifications. A onefold magnification, for example, is obtained in the position illustrated in Fig. 2a. In the position illustrated in Fig. 2b, the inverting system 1 works at a magnification of 2.5 times and in the position illustrated in Fig. 2c 4 times.

[0015] To enable a subjective field of view of at least 22° to be ensured even at low magnifications in a telescope or sighting telescope with a maximum magnification or a maximum zoom greater than four times, the invention proposes a beam deflector device 2. An example embodiment of this is illustrated in Figs. 3a to 3c and in this instance it is provided as an additional lens arrangement integrated in the inverting system 1. The inverting system 1 proposed by the invention and illustrated in Figs. 3a to 3c may be integrated into a sighting telescope of the type illustrated in Fig. 1 instead of the inverting system 1 illustrated in that drawing.

[0016] The optical beam deflector device 2, which by itself does not fall within the protective scope of claim 1, could equally well be mounted in the telescopic device as a separate component, separately from the inverting system 1. However, it would also be conceivable to achieve the optical beam deflection by opting for an appropriate design of the lenses 11, 3a and 3b. At all magnification stages, the optical beam deflector device desirably ensures a subjective field of view of at least 22°, preferably between 22° and 24°, using an optical magnification means, preferably of the inverting system, with an at least five times, preferably an at least six times maximum magnification. To improve control of chromatic aberration, it has proved to be of practical advantage if the optical beam deflector device 2 has preferably two lenses 7 glued to one another, in other words cemented lenses. However, it would also be conceivable for the optical beam deflector device 2 to be designed as a single lens.

[0017] It has proved to be of practical advantage if the optical beam deflector device 2 is disposed on the side of the inverting system 1 facing towards the eyepiece 5. It is also advantageous if it is positioned on the side of the eyepiece-end image plane 10 facing away from the eyepiece 5.

[0018] A particularly simple solution from a design point of view is for the optical beam deflector device 2 to be mounted in a fixed arrangement, in other words so that it cannot move relative to the central tube 6. In some embodiments, however, it may also be necessary to be able to move the optical beam deflector device 2, in which case generally it will be displaceable along the optical axis.

[0019] The central tube 6 of standard sighting telescopes known to date has an external diameter of between 30 mm and 35 mm. This is naturally without taking account of any adjusting turrets 8 or the like which might be provided. This dimension of the central tube 6 is expediently also used for sighting telescopes proposed by the invention.

[0020] The optical beam deflector device 2 has a refractive power of between -20 dpt (dioptres) and -40 dpt, preferably between -27 dpt and -37 dpt. In one specific example, the refractive power is -27.03 dpt, in which case a subjective field of view of 23.5° is obtained at all magnifications.

[0021] Figs. 3a to 3c illustrate the inverting system 1 proposed by the invention, again with the optical elements 3a and 3b provided as a means of magnifying and inverting the image in three different positions. In the position illustrated in Fig. 3a, a onefold magnification, for example, is obtained. Fig. 3b shows the positioning needed to obtain a 3.5 times magnification and Fig. 3c a six times magnification. The optical beam deflector device 2 deflects the beam in order to enlarge the subjective field of view. As a result, the invention enables a subjective field of view of at least 22° to be obtained at all magnifications and a total focal length of less than or equal to 11 mm to be obtained at the maximum magnification. The total focal length of the inverting system 1 proposed by the invention is desirably between 11 mm and 7 mm, preferably between 10 mm and 8 mm, at the maximum magnification due to the beam deflector device 2. In the specific example of the embodiment mentioned, a total focal length of 8.264 mm is obtained at the maximum magnification.

[0022] The size of the subjective field of view 2 w' is determined on the basis of an angular measurement. The corresponding measurement set-up for test pieces with a real exit pupil is illustrated in Fig. 4. An auxiliary sighting telescope 28 is mounted at the exit pupil on that of the test piece on a rotary table with an angle measuring device. An auxiliary sighting telescope 28 with an approximately threefold magnification, an entrance pupil diameter of approximately 3 mm and a sighting mark, such as a reticle, should be used for this purpose. In order to avoid colour fringes in the image, green light with a wavelength of approximately 550 nm is used for measuring purposes. The measurement set-up consists of a sequence of a light source 21, a condenser 22, a filter 23, a diffusor 24, a telescopic device 25 to be tested (test piece), a field stop 26 and an auxiliary sighting telescope 28 at the position 27 of the exit pupil. When conducting the measurement, the pivot axis of the auxiliary telescope is at the exit pupil 27 and in the plane of the entrance pupil of the auxiliary telescope. The pivot axis intersects the optical axis of the test piece 25 and of the auxiliary sighting telescope 28 at a right angle. The auxiliary sighting telescope 28 sharply focused on the field stop 26 of the test piece 25 is pivoted so that its sighting mark is moved successively to diametrically opposed edges of the field of view. The angular difference is read from the scale of the angle measuring device provided on the pivoting table (in degrees).

[0023] The focal length of the inverter system as a whole is measured in accordance with DIN 58189 (edition May 1996) and the measurement may be conducted using commercially available test devices".

28. The amended claims have now been agreed between the parties and broken down into integers. The following table shows the agreed amendments to the claims (in red) and the revised translation that has been agreed to integer 11. The Claimants only claim independent validity for claims 1, 2, 3, 6 and 8.

	CLAIM 1
1	Telescope or sighting telescope,
2	with a central tube (6) disposed between an objective lens (4) and an eyepiece (5),
3	which central tube (6) has a maximum external diameter of 35mm,
4	- and the central tube (6) contains an inverting system (1) in which a displaceable optical magnification means is integrated and which is accommodated in one component
5	and comprises a lens arrangement with at least two optical elements (3a, 3b) which can be displaced relative to one another,
6	- and the inverting system (1) is disposed between an objective lens- end image plane (9) and an eyepiece-end image plane (10),
7	- and the objective lens-end image plane (9) lies between the objective lens (4) and the end of the inverting system (1) facing the objective lens (4),
8	and the eyepiece-end image plane (10) lies between the eyepiece (5) and the end of the inverting system (1) facing the eyepiece (5),
9	- and when at least one of the optical elements (3a, 3b) of the inverting system (1) is displaced, an intermediate image projected by the objective lens (4) in an objective lens-end image plane (9) is magnified
10	with a variable reproduction scale and oriented upright in an eyepiece-end image plane (10)
11	with a maximum zoom greater than four times,
12	- and an optical beam deflector device (2) is integrated in the inverting system (1),
13	and the beam deflector device (2) is provided in the form of an additional lens arrangement
14	disposed on the end of the inverting system (1) facing the eyepiece (5)
15	and has a negative refractive power of between -20 dpt (dioptre) and -40 dpt,
16	- so that a subjective field of view (2 ?') of the telescopic device of at least 22° is guaranteed for all magnifications at which the objective lens-end intermediate image is projected into the eyepiece-end image plane (10),
17	at least for light with a wavelength of approximately 550nm.
	CLAIM 2
1	Telescope or sighting telescope as claimed in claim 1;
2	characterised in that the magnification of the magnification optics of the inverting system (1) is at least fivefold, preferably at least sixfold.
	CLAIM 3
1	Telescope or sighting telescope as claimed in claim 1 or 2;
2	characterised in that the optical beam deflecting device (2) is disposed on the side of an eye-piece-end image plane (10) of the telescopic device pointing away from the eyepiece (5).
	CLAIM 4
1	Telescope or sighting telescope as claimed in one of claims 1 to 3;
2	characterised in that the optical beam deflecting device (2) preferably has two lenses (7) adhered to one another.
	CLAIM 5
1	Telescope or sighting telescope as claimed in one of claims 1 to 4;
2	characterised in that the optical beam deflecting device (2) has a refractive power of between -27 dpt and -37 dpt.
	CLAIM 6
1	Telescope or sighting telescope as claimed in one of claims 1 to 5;
2	characterised in that the inverting system (1) has a total focal length of at most 11 mm in the maximum magnification, at least for light with a wavelength of approximately 550 nm.
	CLAIM 7
1	Telescope or sighting telescope as claimed in claim 6;
2	characterised in that the inverting system (1) has a total facal length of between 11mm and 7mm in the maximum magnification, preferably between 10 mm and 8 mm.
	CLAIM 8
1	Telescope or sighting telescope as claimed in one of claims 1 to 7;
2	characterised in that the optical beam deflecting device (2) is disposed on the end of the inverting system (1) directed towards the eye-piece (5).

29. The figures shown in the Patent are as follows:-




The prior art relied upon by Leica

Naumann

30. Helmut Naumann on "Optics Elements: pocketbook of technical optics" described a simple variable magnification means that provides for two magnification positions, with intermediate positions which require the eyepiece to be re-focused.
31. Figure 9.3.8 showed a negative lens immediately before the second intermediate image (G2) as follows:-

32. Naumann continued:-

"By sliding the inverting systems, the magnification can be changed … A crosshair or the like can be inserted in one of the two image planes; the image plane adjacent to the object lens is preferred when the telescope needs to be adjusted in relation to a fixed direction, because then the conformity does not also depend on the inverting system.

Often, a particularly long distance between the eyepiece and the eye is required, for example for hunting telescopes, on the one hand to prevent the telescope from colliding with the eye through recoil, and on the other hand to ensure that the angles of the eyepiece lens appear larger than all other parts of the telescope, with its mount as small as possible so that the view past the telescope is not unnecessarily covered. Sometimes a negative lens is then provided in the eyepiece, which moves the exit pupil much further out and in addition has a favourable effect on the field curvature".

Mai

33. Mai's US Patent 5,671,088 (23^rd September 1997) describes a sighting scope for a pistol with an inverting zoom relay system ranging from 2.5x to 8x. Figure 1 of Mai was as follows:-

34. Position 34 is the second intermediate image (at which the reticle is placed), and lens 18 is a fixed negative lens prior to that image. It says:-

"Generally, an erector system consisting of an objective lens and an erector lens system (e.g., a four lens system), a reticle (e.g., crosshair) and an eyepiece. These components are typically mounted in an aluminium tube (e.g., a pivot tube). The objective projects an image of a target onto a first image plane, located at the focal point of the objective which is positioned forward of the erector lens system. The erector lens system inverts the image and projects it onto a second image plane. The reticle is located at the position of the second image plane. The eyepiece magnifies the target image together with the reticle.

A magnification change (e.g., from 2.5x to 8x) is accommodated by altering the relative axial position of the inner (forward positioned) two of the four lenses of an erector lens system. This alteration may be conducted by employing a cam tube in combination with the pivot tube housing the erector lenses. If the optical centers of the erector lenses are not aligned, the phenomenon of trackout occurs. Trackout constitutes an image shift resulting from misalignment of one lens relative to the other lens".

Betensky

35. Betensky's US Patent 5,500,769 (19^th March 1996) concerns "viewing systems for use with the human eye such as monoculars and binoculars".
36. Figure 1 of Betensky is as follows:-

37. The summary of the invention included the following:-

"The present invention takes a completely different approach from the prior art. Specifically, rather than designing binoculars based only on the eye's aided dynamic field of view, the binoculars of the present invention are designed based on both the eye's aided dynamic field of view and its aided static field of view. More particularly, in accordance with the invention, it has been determined that the eye's aided dynamic field of view is not the critical field of view in terms of designing binoculars which can be moved relative to the object ... For binoculars, the user can readily, and prefers to, move the combination of his or her head and the binoculars to follow an object rather than trying to move the binoculars relative to the eyes. This approach is 1) easier since it does not upset the alignment of the binoculars with the eye, 2) does not require reaccommodation of the eye due to uncorrected field curvature, and 3) does not lead to erroneous changes in focus if reaccommodation is not sufficient.

By emphasising the eye's aided static field of view, a user of the binoculars of the present invention can employ substantially more of his or her peripheral vision to detect a change in the object scene. Also, by this emphasis, the user has less of a sensation of tunnel vision. These effects make it much easier for people to use the binoculars of the invention over long periods of time which is clearly desirable.

…

A further aspect of the invention involves the eyepiece of the binoculars. As the aided static field of view of the binoculars is increased, obtaining a large eye relief becomes difficult. Correcting off-axis aberrations requires the use of negative lens elements which further exacerbates the problem. In accordance with the invention, it has been found that these problems can be addressed by at least partially corrected off-axis aberrations with a negative lens unit placed ahead of the intermediate image. In this way a large eye relief can be readily obtained.

…

As with the variable power aspect of the invention, the aspects of the invention relating to the use of a negative lens unit before the intermediate image can be used independently of the other aspects of the invention, that is, it can be used with viewing systems generally. …

The [negative] corrector lens unit [C] is located between the reverting and inverting means and the eye lens units in front of the intermediate image. This unit has a negative power and in combination with the eye lens unit serves to correct off-axis aberrations while still allowing the overall optical system to have a large eye relief, e.g., an eye relief of at least 10 millimetres".

Nikon

38. Nikon's Japanese Patent 11326789 A (26^th November 1999) relates to the design of an eyepiece. Figure 1 shows the following:-

39. The description in Nikon includes the following:

"In general, an eye relief of an eyepiece lens ... is about 80% of a focal length of the lens system. Therefore, a sufficient eye relief cannot be obtained in a lens system having a small focal length, which causes shading in a peripheral area of a field of view when the user is wearing glasses. To avoid this, a structure has been used in which a negative lens group and a positive lens group are arranged at the object side and the eye side, respectively, of an intermediate image of an objective lens. In this structure, a large eye relief can be ensured by arranging the negative lens group at the object side. In addition, since the Petzval sum can be reduced by using a negative lens having a large power, a field curvature aberration can be appropriately corrected.

…

Accordingly, an object of the present invention is to provide an eyepiece lens which includes only 5 lenses, which appropriately corrects aberrations over the entire area of a sufficiently large field of view, and which has an eye relief that is larger than or equal to the focal length of the entire eyepiece lens system".

The IOR 2-12x32 riflescope

40. The details of this riflescope are described in the evidence below. Ms Granciu exhibited a drawing of it as follows:-

41. The negative plano-concave lens (124) in Ms Granciu's drawing is ringed in red and
42. The negative plano-concave lens (124) in Ms Granciu's drawing is ringed in red and is contained in a lens group consisting also of a flat glass plate (122). The reticle and the second intermediate image in the IOR Scope are within the lens group immediately to the left of the negative lens.

Leica's riflescopes

43. Leica's riflescopes are specified as having fields of views of, respectively 6.5 metres, 4.1 metres and 2.6 metres at maximum magnification at distances of 100 metres, measured in accordance with DIN/ISO 14490-1 at approximately 550nm wavelength. These are said to equate to subjective fields of view of about 23.4 degrees. The subjective field of view is said to be greater than 22 degrees at all magnifications.
44. Annex 2 to the confidential product description includes the following drawings of Leica's riflescopes. The negative lens in each case is shown as "F":-



The issues

45. Some days after the trial commenced, the parties finally agreed the issues that needed to be determined. It would have been much more helpful to the Court in this case, as in many others, if those issues had been agreed long before, and certainly before the trial began. I have reformulated some of the issues, but broadly stated the issues that were agreed were as follows:-

Issues of construction

46. Issue 1: In integer 3 of claim 1, what is the proper meaning of a "central tube with a maximum external diameter of 35mm"?
47. Issue 2: In integer 4 of claim 1, what is the proper meaning of "the central tube contains an inverting system"?
48. Issue 3: In integer 11 of claim 1, what is the proper meaning of "a maximum zoom greater than four times"? Is this integer so ambiguous as to have no meaning?
49. Issue 4: In integer 12 & 14 of claim 1, what is the proper meaning of "an optical beam deflector device integrated in the inverting system" and of "disposed on the end of the inverting system"?
50. Issue 5: In integer 16 of claim 1, what is the proper meaning of "at least 22º is guaranteed for all magnifications"?
51. Issue 6: What is the proper meaning of claim 2?
52. Issue 7: Does claim 3 add anything to integers 12 & 14 of claim 1?
53. Issue 8: In claim 6, what is the proper meaning of "the inverting system"?

Issues of infringement

54. Issue 9: Do Leica's riflescopes have a central tube containing the inverting system which meets the requirements of integer 4 of claim 1 and the requirements for a central tube with a maximum external diameter of 35mm in integer 3 of claim 1?
55. Issue 10: Do the magnification optics of Leica's riflescopes satisfy the requirements of claim 2?
56. Issue 11: Do Leica's riflescopes have an "inverting system" of the focal length specified in claim 6?

Added matter

57. Issue 12: Was the feature of integers 5 and 9 of claim 1 stated to be "when at least one of the optical elements (3a, 3b) of the inverting system is displaced" disclosed in the application as filed?

Novelty

58. Issue 13: Did the IOR riflescope sold to Realex in Finland in February 2005 clearly and unambiguously disclose all the features of the claimed invention, in particular (a) a maximum zoom greater than four times (integer 11); (b) an optical beam deflector device integrated in the inverting system and disposed on the end of the inverting system facing the eyepiece (integers 12 & 14); (c) a subjective field of view of at least 22º guaranteed for all magnifications (integer 16); and (d) an optical beam deflector device disposed on the side of an eyepiece end image plane pointing away from the eyepiece (claim 3 & 8)?

Obviousness and Inventive Step

59. Issue 14: Was the claimed invention obvious over the common general knowledge alone in July 2005?
60. Issue 15: Was the claimed invention obvious over the IOR riflescope, taken together with the common general knowledge?
61. Issue 16: Was the claimed invention obvious in the light of the teaching of Naumann, taken together with the common general knowledge?
62. Issue 17: Was the claimed invention obvious in the light of the teaching of Betensky, taken together with the common general knowledge?
63. Issue 18: Was the claimed invention obvious in light of the teaching of Mai, taken together with the common general knowledge?
64. Issue 19: Was the claimed invention obvious in light of the teaching of Nikon, taken together with the common general knowledge?

Sufficiency

65. Issue 20: Does the Patent contain sufficient information, taken together with the common general knowledge to enable a skilled person to perform the invention?
66. Issue 21: Is integer 11 of claim 1 so ambiguous as to render the Patent insufficient?

Swarovski's factual evidence

67. Dr Andreas Zimmerman was Swarovski's first factual witness. He has been the manager of Swarovski's patent portfolio since 2007 (so some time after the priority date). His first statement dealt with the way in which he had chosen a number of prior art brochures from Swarovski's archives. He said that he had not deliberately excluded brochures dealing with riflescopes with a zoom ratio higher than 4. Though such scopes were available before the priority date, they were not, he said, common. In cross-examination, he accepted that he had only looked for brochures where there was a cross-section which showed the layout of the lenses inside.
68. Dr Zimmerman also set out the field curvature of riflescopes commercially available before the priority date, taken from a 2012 article in a German magazine entitled "DWJ". I shall return to the figures for field curvature at each of maximum and minimum magnification contained in that article in due course.
69. Dr Zimmerman then provided the sagittal (but not the tangential) field curvature values for Swarovski's Z4 and Z6 ranges of riflescopes (at maximum and minimum magnification). The Z4 range is designed similarly to the prior art shown in Figure 1 of the Patent. The Z6 range is made in accordance with the Patent. Dr Zimmerman concluded that the figures he gave for field curvature values are typical even for high performance premium riflescopes. In cross-examination he said that he had obtained that information from Swarovski's experts, not from his own knowledge or understanding. He said that he did not therefore consider that Professor Rogers was correct to say that the skilled person would try to correct field curvature to a level of 0.5 dioptre, and that field curvatures of up to 1.7 dioptre are commercially acceptable (though his tables did not show any greater curvature than +1.5 dioptre). His first statement concluded by saying: "Field curvature is therefore not seen as an issue when designing or marketing riflescopes, which is the reason why there is little publicly available information or discussion on it nowadays or in the past before the priority date …". He accepted, in effect, that this evidence was not derived from his own expertise, but from the article he cited and from Swarovski's experts.
70. In his second witness statement, Dr Zimmerman qualified what he had said about the field curvature measurements in the DWJ article he had cited, broadly accepting what Mr Albrecht had said in his 4^th statement (as to which see below). The only point that Dr Zimmerman contested was where Mr Albrecht had said that the DWJ data did not correspond to either field or image curvature values. He explains as follows:-

"5. [Mr Franz Erler, the Head of Swarovski's Quality Control Department] has explained to me that, in a well-corrected system, the dominant component of the aberrations measured using this test will be the sagittal field curvature. This is because it is a visual test and the eye will tend to look at the brightest image surface in preference. The tangential image surface usually suffers at the edge from vignetting to a greater degree than the sagittal image surface and so is not as bright as the sagittal image surface. Furthermore coma and chromatic aberration are associated more with the tangential image surface than the sagittal. As the dominant component is sagittal field curvature, the DWJ article's data does correspond to field curvature values contrary to Mr Albrecht's statement.

6. For this reason I believe that paragraph 7 of my first Witness Statement remains correct as the DWJ article does indicate that field curvature values up to 1.7dpt are commercially acceptable for riflescopes".

71. I found Dr Zimmerman to be a reliable witness, albeit that most of what he said emanated from Swarovski's technical department.
72. Dr Hannes Burger and Ms Sally Sunkel provided witness statements concerning the translation of the Patent. This evidence ceased to have any relevance once the translation was agreed at the start of the trial.

Leica's factual evidence

73. Mr Stephan Albrecht is the Division Manager of Sports Optics of Leica Camera AG. Three of his witness statements were relied upon by Leica. He was not cross-examined.
74. Mr Albrecht's 2^nd statement verified Leica's product description. Mr Albrecht's 3^rd statement described the tests that he had conducted on the IOR 2-12x32/MP8/IL riflescope with serial number 04804 (the "Tested IOR riflescope"). The Tested IOR riflescope was x-rayed to establish the location of its lenses and the apparent field of view was measured according to the method described in the Patent. Mr Albrecht's figures for the angular field of view for various dioptre settings (to adjust for the long-sightedness of the user) were as follows:-

Magnification	Angular field of view (0 dptr)	Angular field of view (+5 dptr)	Angular field of view (>+ 5 dptr)
Minimum magnification (2x)	17.53	21.45	22.87
3.45x	21.89	25.94	26.92
Maximum magnification (12x)	22.24	> 25.94	>26.92

75. Mr Albrecht accepted that the x-ray analysis was not a conventional way to try to determine optical design information.
76. Mr Albrecht's 4^th statement dealt with the information contained in the DWJ article exhibited by Dr Zimmerman. In short, Mr Albrecht concluded that what Dr Zimmerman had referred to as the "field curvature" data for several common riflescopes was in fact, properly translated "marginal/edge resolution" or "marginal definition field of vision", and that "edge resolution of the field of view is influenced not only by field curvature, but also by astigmatism, coma and colour fringes". Mr Albrecht also said that what DWJ's journalist had measured was an "integral measurement of the edge resolution at 90% field of view height in comparison to 10% field of view height without any DIN or ISO reference". He gave sagittal and tangential image curvature values at minimum and maximum magnification for Leica's Magnus 1-6x24 riflescope, which did not accord with the figures given for that riflescope in the DWJ article, and concluded that the data in that article did not correspond to either the field or image curvature values.
77. Ms Dana Granciu is a scientific researcher employed in the field of optics and optical design by IOR S.A. in Romania. She developed the IOR riflescope (2-12x32/MP8/IL). In her first statement, she explained that the design of the eyepiece and the lens elements was the same as for the parallel designed models 1.5-8x26 and 3-18x42. The IOR riflescope has a central tube with a diameter of 35 millimetres, and a zoom relay/erecting system which comprises first and second movable lens groups housed within a mechanical assembly that also houses the field lens (at the objective end) and the negative lens group (at the eyepiece end). The negative lens group has a refractive power of 26.5 dioptres, and comprises two components: the first a plate of glass with parallel faces on the objective side, and the second a plano-concave lens with its concave face facing towards the eyepiece. Each of these two components incorporates some of the reticle design.
78. Having described the operation of these IOR riflescopes, Ms Granciu then gave her figures for the apparent field of view of the IOR riflescope as follows:-

Magnification	Apparent field of view
2	18.4°
2.3	20.3°
2.4	20.9°
2.5	21.5°
2.7	>22°
4	>22°
6	>22°
8	>22°
10	>22°

79. Ms Granciu also said that the IOR riflescope was exhibited at the February 2004 SHOT show in Las Vegas, and went into commercial production later in 2004.
80. The only parts of Ms Granciu's 2^nd statement which were admitted were paragraphs 2-6 which gave further information about the second intermediate image for the IOR riflescope. In short, Ms Granciu says that the second intermediate image is coincident with the interface between the negative lens and the flat glass plate cemented to it on its objective side, when the object distance is at infinity, but that, as the object distance decreases, the second intermediate image moves towards the eyepiece. The object distance at which the second intermediate image is axially wholly outside the negative lens towards the eyepiece varies with magnification so as to be so: (a) where the object distance is 96.5 metres or less at 12x magnification, and (b) where the object distance is 24 metres or less at 6x magnification, and (c) where the object distance is 2.85 metres or less at 2x magnification. Finally, Ms Granciu said that the apparent field of view was at least 22 degrees for the IOR riflescope for magnifications in the range 2.7 to 12, representing a zoom factor of 4.44.
81. In cross-examination, Mr Andrew Lykiardopoulos, counsel for Swarovski, showed Ms Granciu an example of an IOR riflescope with a parallax adjustment knob to bring the intermediate image plane back in line with the reticle. She accepted that this was used, because if objects are viewed closer than 100 metres at high magnification, the intermediate image plane moves away from the reticle. This adjustment is to avoid parallax error, which can cause aiming error, and which occurs when the object image plane is not coincident with the reticle plane. I had no reason to doubt Ms Granciu's reliability as a witness.
82. Mr Christof Heintz is employed by Carl Zeiss Sports Optics GmbH as patent coordinator and optical designer. He dismantled and tested an IOR 3-18x42 riflescope with serial number SN 02507. He gave the focal lengths of the optical elements of the IOR lens and calculated optical power of the negative lens at -26.55 dioptres. Mr Heintz accepted in evidence that there was no photographic record of the tests he had undertaken, and that the scope in question was purchased in 2007.

Expert evidence

83. Before dealing with the expert evidence, it is important to mention that the identity of the skilled person was not in issue between the parties in this case. Though the design of a riflescope of this kind would involve a team, the optical designer would be the person primarily interested in the Patent. That person would have a first degree in physics or a related subject, and perhaps a second degree in optics and some years of design experience.

Dr Brian Blandford

84. Dr Brian Blandford ("Dr Blandford") worked in industry as an optical designer for 31 years until 2002, since when he has acted as an independent consultant. Dr Blandford has, over the years, acted as a supervisor and external examiner for BSc, MSc and PhD students at several universities including Imperial College and Reading University. Dr Blandford is the named inventor for 6 patents.
85. In his first report, Dr Blandford concluded that the Patent's invention was not obvious to the skilled person in 2005 either from his common general knowledge or from the 4 written forms of prior art relied upon. He also concluded that Leica's riflescopes infringed claims 1, 2, 3, 6 and 8 of the Patent.
86. Dr Blandford expressed the view that the location of the reticle at the second (rather than the first) intermediate image is essential if the zoom range is large, because otherwise the reticle lines "would appear to vary in width with the zoom motion and at high magnifications would obscure the object being viewed".
87. Dr Blandford's cross-examination began with an explanation of the concepts of sagittal and tangential rays or fields of view. In essence, Dr Blandford explained that, in the presence of astigmatism, the rays in the plane which contains the direction of the field of view are called tangential rays and they form a sharp focus in one plane, but rays in the other direction will form a focus in another plane. This results in parts of the field of view which are tangential to the edge of the image being clearly in focus. If you focus on the other plane, the sagittal (or radial) rays are focused on that plane. The fact that they are not the same plane is evidence of astigmatism. In essence, astigmatism is when the view of a vertical line is at a different plane from the view of a horizontal line.
88. Dr Blandford did not accept that the eye always dealt with the confusing situation caused by the tangential and sagittal views not being coincident by focusing at a point between the two images. His view (though he did not claim to be an expert on the point) was that "because there are situations where the sagittal field of view is flat and the tangential field of view is so steeply curved that the eye cannot accommodate it … that the eye chooses the field with which it is most comfortable, namely the sagittal".
89. Dr Blandford broadly accepted the following propositions suggested to him by Mr Michael Hicks, counsel for Leica in relation to the use of astigmatism to palliate Petzval field curvature:-

i) It was well known that astigmatism can be used to palliate the effect of Petzval field curvature in the field of view rendering an otherwise unacceptable image more acceptable to the eye. His proviso was that it is only generally in one of the two image surfaces that it is more acceptable.

ii) In order to palliate Petzval field curvature using astigmatism, one starts with the knowledge that in an optical system with positive lenses, the Petzval Sum will tend to curve the image away from the eye of the observer at the edges.

iii) Astigmatism will result in two curved surfaces of focus, the tangential and the sagittal, and one aims to ensure that at least to some extent those tangential and sagittal curved surfaces curve in the opposite direction to the Petzval Sum to palliate the effect of Petzval field curvature. The movement of the sagittal surface and the tangential surface are always in the same direction from the Petzval surface. The tangential surface moves three times that of the distance of the sagittal surface.

iv) One attempts, therefore, for the sagittal and tangential curved surfaces, to counteract the curved surfaces created by the Petzval Sum to try to produce a flatter image.

v) There is a limit to how much that can be done, because the curved surface of the sagittal image is different from the curved surface of the tangential and as one gets further to the edge they become too far apart and the eye sees a blurred image, or gets confused, or chooses to focus on one or the other.

90. Dr Blandford agreed that there were 5 reasons why in practice a zoom facility on a telescope might be useful:-

i) To see more of the outside world at lower magnifications;

ii) At lower magnifications the image will be less prone to jumping about because of shaking of the optical instrument, whereas at high magnifications, any shaking will be much more noticeable;

iii) In some conditions, for example at night or in dim light, a lower magnification may produce a brighter image;

iv) The image may be sharper at lower magnifications, in the sense that the optics may be able to cope with lower magnifications better than at higher magnifications; and

v) A higher magnification will enable the object to appear larger, which may be useful if one is trying to shoot a small object a long distance away.

91. Dr Blandford was asked about the essentials of zoom, and explained the following principles in cross-examination:-

i) A zoom is a continuous user-controlled change in focal length or magnification that maintains focus and image quality over the entire range of lens movements, so as to keep the first and second intermediate images in the same place while that happens.

ii) The benefit of a zoom system is that the user does not have to refocus the objective or the eyepiece at any magnification, so as to maintain the accuracy of the target upon the reticle.

iii) To achieve this effect, both lenses in the system must move. The movement of one of them is linear, but the other has a non-linear motion which stops and changes direction.

iv) The production of zoom systems is complex because of the difficulty of producing the cams, and a 1-6x zoom is more difficult to produce than a 1-3x zoom.

92. Dr Blandford was shown examples of riflescopes where the designers had placed the reticle at the first intermediate image, and was taken through the advantages and disadvantages of so doing. His conclusion was that, for a large zoom ratio, the user would prefer to have the reticle at the second intermediate image (for the reasons given in his first report).
93. Dr Blandford was asked about the tunnel effect and the causes of it. In relation to the IOR riflescope, he said that he understood that it suffered from "an incipient tunnel effect in which the black ring is not in focus except to the extreme wide view field. The first field stop is not … visible until the very end of the zoom range. Up to that point, the subjective field of view begins to suffer from the encroachment of mechanical components within the inverting system". He was then asked about the reasons for the tunnel effect in more detail. He said:-

i) At the highest magnification, the field of view is determined by the size of the field stop at the second intermediate image.

ii) As the magnification reduces, at some point the subjective field of view decreases. This is not caused by the field stop at the second intermediate image. It is caused either by a field stop at the first intermediate image, or by lens holders, the side of the tube, or other mechanical parts impinging upon the light going down the tube. The latter causes vignetting, namely a gradually dimming outer rim, rather than a sharp outer rim caused by a field stop.

iii) Generally designers would use a field stop at the first intermediate image to prevent vignetting.

iv) In Dr Blandford's opinion, the increased field of view of the outside world at low magnification was the most important advantage of a zoom system.

94. On the second day of his cross-examination, Dr Blandford was asked about Professor Rogers's statement of the advantages and disadvantages of placing a negative lens at various positions in order to reduce field curvature.
95. Dr Blandford's basic position was that:-

i) If field curvature is a problem, then the insertion of a negative lens is the obvious solution.

ii) Dr Blandford disagreed with Professor Rogers generally over the extent of the significance of field curvature. He questioned whether a designer would be induced to insert a negative lens at all in order to correct field curvature. But if he did only wish to correct field curvature, he would have to put the negative lens in the eyepiece as Ms Granciu did with the IOR riflescope.

iii) Modular design was an industry standard across the world, and its importance had not been diminished by the greater use of computer design software. Thus, Dr Blandford's view was that each system (objective, inverting and eyepiece) would be designed separately.

96. Dr Blandford was asked about the 6 different possible positions for a negative lens suggested by Professor Rogers. He thought that only positions A, B or C (after, on or before the second intermediate image) were real possibilities. The first two were satisfactory positions, but required redesign of the eyepiece. He accepted that the insertion of a negative lens immediately before the second intermediate image had the advantage of flattening the image more than the other two positions, but he did not think that was an important factor. Dr Blandford did not think that the advantages and disadvantages identified by Professor Rogers were, in any sense, basic or elementary optics.
97. The following exchange between Dr Blandford and counsel concerning position C (before the 2^nd intermediate image) was important:-

"Q. We have discussed position (C) previously. One advantage which we have discussed which is not present in positions (A) and (B), amongst other others, is that if you put the lens in this position, you flatten the image so that you present a flatter image at the second intermediate image?

A. Yes, to some extent.

Q. That is an advantage which is not present in positions [(A) and (B)]?

A. Yes, that is true.

Q. Now, I want to discuss with you your concerns about position (C) …

We discussed the two concerns or disadvantages that Professor Rogers mentioned, and I think you had another concern or disadvantage that you wanted to identify about position (C).

A. One of the difficulties is that position (C) in this very schematic diagram does not discriminate as to whether the lens is close to the intermediate image and therefore constitutes a field lens essentially no different from positions (A) and (B) or is there a significant distance between the lens, in which case it has a significant effect on the magnification of the inverting system.

Q. Yes, if you move the negative lens towards the relay elements, as we discussed, it increases the magnification of the zoom relay system?

A. It does.

Q. What I was trying to identify is what was your concern about a position of the negative lens, say, halfway between the zoom relay system and the second intermediate image, to take an example?

A. I think my concern was that it is not intuitive because it reduces the physical distance available for the zoom motion.

Q. But if we took your figure 1 as representing the most right-hand movement of lenses 3a and 3b or look at your enlarged cutaway on page 2 of your exhibit, there, we would suggest, is plenty of room there to stick a negative lens … between the zoom relay system and the second intermediate image in that drawing.

A. There is room, but if you look at the extent of the zoom carriage of the right-hand lens, the room available would force the negative lens right up against the second intermediate image and therefore constitute a field lens.

Q. I want to suggest to you that you could simply stick it midway between the last of the zoom relay elements and the second intermediate image, where there is plenty of space for it in that diagram.

A. Yes, it would fit ----

Q. It would fit.

A. ---- but it would still be more of a field lens than a lens which would influence the size of the second intermediate image.

Q. If it is halfway between the two, it would have an effect ----

A. An effect, yes.

Q. And I think we accept that if you moved it more to the left, it would increase the size of the second intermediate image more.

A. Yes.

Q. If you moved it more to the right, it would magnify it less.

A. Yes.

Q. So you choose the position horizontally so far as you can to give you whatever extent of magnification you want.

A. Yes.

Q. But your concern then about position (C) was primarily, if I can put it this way, a mechanical one: would there be a space to put it between the end of the zoom relay and the second intermediate image?

A. I think, and I am sorry to say this, my disagreement with Professor Rogers was over the significance of field curvature in commencing this entire exercise. We do differ on the extent to which field curvature is acceptable and the extent to which you need to introduce measures such as this to correct it.

Q. I understand that. In other words, you question whether you would be induced to put a negative lens in at all?

A. Exactly" (emphasis added).

98. There are some important limitations in the design of riflescopes that were discussed in the cross-examination of Dr Blandford. They included:-

i) The need for 80-90 mms of eye relief so that the user was not hit in the eye during rifle recoil; and

ii) The need for the eyepiece and tube to be small enough to allow the user to see over or round them.

99. The designer seeking to increase the power of the zoom would, according to Dr Blandford, either extend the travel of the inverting system or increase the power of the inverting lenses. In the second case, he accepted that the insertion of a negative lens was an obvious solution to improve field curvature caused by the increase in the Petzval Sum of the positive lenses.
100. Dr Blandford was then asked about each of 5 elements of prior art relied upon.
101. In relation to Naumann's 1992 publication, Dr Blandford had concluded in his reports that Naumann had used a weak negative lens in its eyepiece. He thought that there was nothing in Naumann to suggest the use of a strong negative lens in an inverting system to improve zoom ratio, while maintaining the same subjective field of view at all magnifications.
102. In cross-examination, Dr Blandford questioned whether the reticle could really be placed at position G2 (the second intermediate image), when the negative lens was part of the eyepiece. He said that the claimed advantages of increased eye relief and improved field curvature would be obtained whether the negative lens was to the left or the right of the second intermediate image. Dr Blandford also agreed with Professor Rogers that it would be obvious to a skilled person that, if the inclusion of a negative lens in a switch system is of advantage, it would be equally applicable to a continuous zoom system. He accepted that the negative lens in Naumann might be 'strong', and said that it was not uncommon for parts of the eyepiece to be on the objective side of the second intermediate image, and that it was, therefore, possible to have the second intermediate image inside the eyepiece.
103. In relation to Mai, Dr Blandford explained that it was a patent concerned with a mechanical invention designed specifically to minimise the problem of the reticle appearing to wander over the image as the magnification is changed.
104. Dr Blandford accepted that his initial statement that the negative lens in Mai was weak was incorrect, and that it was, on Professor Rogers's figures something in the order of -20 dioptres. He also accepted, within limitations, that a skilled person reviewing the Mai patent would appreciate that a strong negative lens at the end of the erecting system would have the advantages described by Professor Rogers in relation to his position C for a negative lens. His "main hesitation about Mai" was that the negative lens was "thin and a single element and we have a general rule of thumb in optics that powerful lenses creates more aberrations. The way of curing those aberrations is to turn single elements into doublet elements as a way of alleviating that".
105. In relation to Betensky, Dr Blandford said in his report that the zoom factor which could be achieved by the mechanism shown in figures 2 to 4 was much lower than that shown in the Patent, and that such a mechanism would interfere with the placement of a reticle.
106. In cross-examination, Dr Blandford agreed that someone looking at Betensky would realise that placing a negative lens in an optical system comprising an inverting or reverting unit and an eyepiece would provide the benefits of the "waist effect" (when the lens is on the objective side of the intermediate image), somewhat flattening the image, and improving the eye relief (up to 10 millimetres). Dr Blandford pointed out that such an eye relief was inadequate for a riflescope.
107. In relation to Nikon, Dr Blandford said in his report that, because a designer would look at an optical system as a series of sub-systems, Nikon would be unsuitable for a zoom sighting telescope, because the reticle could not be placed at the second intermediate image. In cross-examination, Dr Blandford pointed out that the improvement of the eye relief (to 18 millimetres) was not enough to work for a riflescope.
108. Dr Blandford expressed the view in his report that the negative lens in the IOR riflescope (to the right of the intermediate image) was part of the eyepiece. In cross-examination, Dr Blandford agreed that the lens doublet with the second intermediate image and the reticule sandwiched in the centre was done in that way to avoid dust particles at the intermediate image appearing in the user's view and causing problems. Dr Blandford also agreed that Ms Granciu's theoretical calculations showed that, when the magnification is above 2.7 times, the apparent field of view was greater than 22 degrees.
109. Dr Blandford was asked about Professor Rogers's view that 0.5 dioptres was an appropriate target for image curvature because it corresponds to the eye's maximum depth of focus. He agreed that 0.5 dioptres is the natural depth of focus of the eye, but he did not agree that the optical designer would choose that as a target depending upon the price of the instrument, because he said that the designer of riflescopes is given very little choice because of restrictions of length, weight and diameter. In re-examination, Dr Blandford said that there seems to be a preference for the eye to select the sagittal image over the tangential image and that he would take an upper limit of, say, 2 dioptres to be the acceptable curvature for the sagittal image.
110. Dr Blandford's position was that none of the brochures he had seen for riflescopes in 2005 with zoom ratios up to 4 (save for one Weaver scope which did not have a clear diagram) had a negative lens where an optical designer would normally choose to place one to reduce field curvature. From that, he concluded that the optical designers had decided that field curvature was not a sufficient problem at that point.
111. Dr Blandford accepted that the measurements in the DWJ article relating to edge sharpness measured in dioptres indicated that field curvature was the factor they were concerned about.
112. Finally, Dr Blandford said that there was nothing magic about the figures in the Patent of (a) 22 degrees for the subjective field of view, and (b) the zoom factor of 4, and (c) the strength of the negative lens of between -20 to -40 dioptres.
113. I found Dr Blandford an impressive and reliable expert witness. He was ready to accept that he had made a mistake, where he had. He was open and candid, and was able to give me genuine assistance as to the likely approach of the notional person skilled in the art.

Professor Rogers's evidence

114. Professor Philip Rogers MBE has been an optical design consultant since 2006, and Visiting Professor at Cranfield University, teaching Optical Design and Fabrication on the MSc course on Ultra-Precision Technologies. Up to 2006, Professor Rogers had pursued a career with various employers as an optical designer. In 1990, he was appointed a MBE for services to optical design. He has been named as an inventor on 27 optical patents. He accepted in cross-examination that he had had a glittering optics career in industry, as a consultant and as an academic. Professor Rogers produced five expert reports.
115. The first report produced exhibit PJR-7 intended to illustrate the effects of placing a negative lens in various positions in the telescope shown as prior art in Figure 1 of the Patent. He concluded that the position specified in the Patent (which he described as position C – placing the negative lens on the objective side of the second intermediate image) was "one of the obvious places".
116. In exhibit PJR-7, Professor Rogers sets out the advantages and disadvantages of each of six positions (A to F). Only positions A, B and C assumed any real importance in the evidence. Accordingly, I set out here the slides produced by Professor Rogers indicating the advantages and disadvantages of each of these positions, none of which was much disputed by Dr Blandford:-

117. Professor Rogers's conclusions on common general knowledge in his first report were, essentially, that the skilled person would know and understand the Petzval Sum and how to reduce field curvature by means of a negative lens, and that long eye relief would be required for a riflescope, and that that would necessitate either an eyepiece of long focal length, or the inclusion of a negative lens in a position somewhere between the eyepiece and the zoom relay. And that the skilled person would have been able to perform the exercise he had done in exhibit PJR-7 and would have considered (at least) positions B and C as possible locations for the negative lens if he had wanted to reduce the image curving effect of the Petzval Sum.
118. In cross-examination, Professor Rogers first accepted that a modular approach was a perfectly normal way to design telescopes in July 2005, and that the Zemax software, which helped designers evaluate and optimise an optical system, had been in wide use long before 2005.
119. Professor Rogers accepted the basics of riflescope design in 2005 namely that:-

i) It should be optimised at a notional distance of about 100 metres;

ii) It would require eye relief to allow for recoil of 80-90 millimetres;

iii) Subjective field of view typically varied between 17 and 23 degrees for zoom factors of 4 or below, but most were about 20 degrees, which was practically regarded as acceptable;

iv) Field stops were used to produce sharply defined edges.

120. Professor Rogers then agreed that in 2005, four commonly known ways to alleviate field curvature were as follows:-

i) The use of astigmatism to palliate the effect to an extent;

ii) Scaling up the size of the instrument in length and diameter to reduce the power of the lenses;

iii) Accepting some curvature of the image around the edge and masking it with a field stop; and

iv) The introduction of a negative lens in the system to counteract the effect of the positive lenses.

121. There was a somewhat academic section of cross-examination about the operation of the human eye when faced with field curvature. This had led Professor Rogers to coin the term "image curvature" to reflect what the eye actually saw when an image was affected by field curvature – which would be somewhere between the sagittal and the tangential field curvature. I am not sure that there was as much substantive difference between the evidence of the two experts as may have at times appeared. But Professor Rogers thought that one had to be "careful in making strong statements because we are always talking about the eye and how the brain interprets it, but the most likely scenario is that the eye will always get the best compromise image and if there is both sagittal and tangential content it will in general try to focus halfway between the two". It will be recalled that Dr Blandford had spoken of the eye's confusion and the possibility of the eye focusing on one of two fields (perhaps particularly the sagittal) or seeing a blurred image. It seems to me that all these are possibilities in different circumstances, but that Professor Rogers's concept of 'image curvature' somewhere between the two is not dependent upon the eye actually being able to focus at that point in a particular case.
122. In cross-examination, Professor Rogers accepted that he should have said that "image curvature of significant (or any appreciable) magnitude would be highly objectionable", rather than "image curvature of any magnitude would be highly objectionable". He qualified the statement in his first report that "… a skilled person would immediately appreciate that field curvature due to the Petzval Sum would be a very significant factor", by saying that "it is a significant factor; it is not the only factor". In his first report, he had also identified a maximum value of +0.5 dioptres for image curvature over an apparent field of view of 22 degrees as being possibly acceptable for a riflescope of reasonable quality. This led to a detailed exchange of reports concerning the eye's accommodation and the acceptability or otherwise of field and image curvatures at different values between +0.5 and about +2 dioptres. I did not gain much from these exchanges nor from the cross-examination that they spawned. Plainly, a designer would be happy to reduce image curvature to +0.5 dioptres, which the eye can accommodate, on any analysis, without refocusing. It is impossible and unnecessary to identify precisely the objective of a skilled person undertaking the design of a riflescope in 2005. It is common ground that such a person would be aware of the effects and the complexities of field curvature and of the Petzval Sum. One might have been forgiven for thinking at some stages in this litigation that field curvature was the only factor that such a designer would be considering. As will later appear, I am entirely satisfied that that is simply not the case.
123. When Professor Rogers was being asked about the availability of riflescopes with zoom factors above 4, he was asked whether he was suggesting that price prevented people producing such riflescopes in 2005. His answer was, I thought, important. He said "[t]he technology moves on". This answer reminded me of the core question of whether it moved on, in this case, by invention or by the use of common general knowledge. At a more pedestrian level, Professor Rogers accepted that the parties had only been able to come up with some four riflescopes as at July 2005 with zoom ratios above 4, and all of them suffered from a loss of subjective field of view at low magnifications. These scopes were the Weaver V10 (with a zoom ratio of either 4.3 or 5), which had a subjective field of view of 14 degrees at the lowest magnification, the US Optics' SN2 (zoom ratio of 5.5), SN3 (zoom ratio of 5), and the IOR riflescope (with a zoom ratio of 6) which loses subjective field of view from below 3.45x magnification.
124. Professor Rogers was asked about the lens configuration of a series of widely available riflescopes as at July 2005. Those which had a negative lens at all tended to have it in the eyepiece some way to the right of the second intermediate image, which Professor Rogers did not really regard as being his position A. He commented as follows:-

"You asked me whether they did not think it necessary to add a negative lens. You were making the point, correctly, that most scopes around in 2005 had a relatively smaller zoom ratio of only 4 whereas we are talking about 6 now. Going from a zoom ratio of 4 to a zoom ratio of 6 would necessitate an increase in the power of those lenses marked 4 in this particular diagram to achieve the higher zoom ratio inside the same length or the same inverting system length by quite an appreciable amount (very, very roughly 30%) which therefore increases field curvature of the inverting system which is substantial anyway by 30%. If you then add on top of that the need to have a larger subjective field of view at the low magnification end, you are increasing the field curvature effects and, therefore, you are increasing the need to add a negative lens. The designers in this case did not think it necessary because they thought it was adequately good enough. If the requirements are more stringent, then the necessity of adding a negative lens somewhere becomes greater".

125. Professor Rogers identified four pre-2005 riflescopes from Kassner, Zeiss, Hakko and Seeadler, as having a negative lens positioned close enough to the second intermediate image in the eyepiece to be regarded as a half-way house to his position A. He accepted that the design of riflescopes did not appear to have changed much from early 1990 to 2005. The manufacturers were using tried and tested designs, and there was a striking consistency of approach towards lens positioning.
126. When asked about the suggestion that it was his evidence that position A was common general knowledge as at July 2005, Professor Rogers said:-

"[t]his is actually fairly standard in wider-angled eyepieces, not so much in -- well, it was not in riflescope eyepieces mainly because of the need to correct Petzval Sum was not quite as great. The point I am making here is that a negative lens would be needed somewhere to reduce Petzval Sum given the more stringent requirement for, shall I call it, an enhanced riflescope, not the sort of examples we have been looking at".

127. Professor Rogers accepted that position B for a negative lens was not utilised in any of the commercially available examples of riflescopes in July 2005. Position C was utilised only in the 1978 Weaver-Scope, where there was a weak negative lens within the inverting system a short distance to the left of the second intermediate image. Consequently, Professor Rogers accepted that position C was not a commonly used position for a negative lens by 2005. He commented:-

"In all the commercial cases we have been looking through, there were not the same stringent requirements, i.e. not the increased zoom ratio, which makes the need for a negative lens greater and, in most cases, not either the provision for an unchanged field of view across the full zoom range, which also makes the requirement for a negative lens greater. Therefore, in most cases, there is no negative lens because obviously they did not see the need in those less stringent conditions".

128. Professor Rogers was asked about the approach he had adopted and whether he had, in effect, worked back from the Patent in dealing with common general knowledge. I found the following exchange instructive:-

"Q. This is right, is it not, effectively knowing the end goal you want to achieve, you have looked back and found by a series of steps how it is obvious to achieve that goal? That is sort of how your approach has been.

A. In a way, but that is saying I have two specific things to solve. Because of the increased zoom ratio and the increased field of view at the lowest magnification, I know I have a field curvature problem, i.e. an image curvature problem as well, therefore I know one part of the solution is to use a negative lens. It then narrows it down to saying, well, yes, but what extra thing do I need to achieve? One of those is to try and get an enhanced subjective field of view at low magnification down a tube of fixed dimensions. That would tend to then lead on to where you place that negative lens.

Q. All this thought process is because that is what the patent is about.

A. The [P]atent is about that indeed, but that is the way a designer's mind would work. The idea of putting a negative lens in a system to do things like decrease field curvature and increase eye relief are known. It is known, for example, by putting a negative lens very close to the second intermediate image, but here there is an extra problem to solve, which is the idea of getting a larger field of view down a relatively narrow tube".

129. Professor Rogers was asked about his conclusion in paragraph 190 of his first report saying: "I think it is obvious to include a negative lens in the position shown in Figure 3 of the Patent to improve field curvature, and therefore useful field of view. It is obvious to do so in light of the common general knowledge and the cited prior art. In particular, it was well known that locating a negative lens between the zoom relay system and the second intermediate image plane would improve image quality (by reducing the field curvature effects of the preponderance of positive lenses) and thereby increase the useful apparent field of view". He accepted that he had seen the negative lens in position C nowhere, but said that "[t]he Mai patent shows it rather clearly", and "Weaver does show a negative lens as well. Okay, it is not a particularly strong negative lens …". But he accepted that when he wrote the conclusions to his first report, he did not know about the Weaver Scope and had not had the Mai patent in mind.
130. In relation to the Patent, Professor Rogers accepted that maintaining the field of view at low magnifications with higher zoom scopes was a concrete benefit. There followed an unimpressive piece of evidence in which Professor Rogers was being asked whether a designer in 2005 (with a prescription and specification for an existing riflescope, the Patent's teaching telling him that he needed a negative lens of -20 to -40 dioptres in position C, and knowing what he was intending to achieve in terms of subjective field of view and waist effect) would be able to predict the performance of that telescope and to make such a telescope without undue difficulty. He prevaricated in answering this question, but ultimately agreed that a designer could do so. In closing, Mr Hicks reminded me that Professor Rogers had said in his report that the Patent lacked any specification for length or weight or the quality of the image required, so that those were the limitations on creating a riflescope from the material in the Patent. He had not, according to Mr Hicks, said that, given reasonable specifications, he could not do so.
131. When asked about the IOR riflescope, Professor Rogers accepted that the negative lens there (numbered 124 on the drawing above) was located at his position B, just to the eyepiece side of the second intermediate image. This gave the advantages of increased eye relief and reduced image curvature, but not the advantage of the waist effect and the other advantages that Professor Rogers identified if position C were used.
132. Professor Rogers also seemed to accept in cross-examination that the figures given by Ms Granciu for the movement of the second intermediate image to the right of the negative lens at high magnifications and at close range were really rather unrealistic for two reasons. First, the user would not be likely to use high magnifications when focussing on a target at close range, and secondly the IOR scope was anyway equipped with a parallax adjustment dial that enabled the user to bring the second intermediate image back into the same plane as the reticle. I asked Professor Rogers how the user could actually know that the second intermediate image had moved away from the reticle. He told me that the reticle will start to appear out of focus, and the reticle will move relative to the target when the user moves his or her head. I thought that the hunter using such a riflescope might not have the time to adjust the parallax if trying to shoot a moving target, but that may not much matter to what I have to decide. Ultimately, it seems to me that the question of parallax changes addressed by Ms Granciu and the experts is something of a red herring. In normal usage of the IOR riflescope, the reticle and the second intermediate image are coincident at the junction of the lens doublet with the negative lens immediately to its right.
133. Professor Rogers was then asked about Mr Albrecht's calculations of the subjective field of view for the IOR riflescope that varied between 17.53 degrees and 22.24 degrees at different magnifications at the 0 dioptre setting, but changed to between 22.87 and >26.92 degrees at the >+5 dioptre setting. Again, Professor Rogers agreed that the measurements at +5 dioptres were quite unrealistic since few people are actually so long-sighted, and if they are, they generally wear correcting spectacles – particularly when out hunting. In short, the measurements for the subjective (angular) field of view of the IOR riflescope at the 0 dioptre setting are the only ones that really matter. Dr Blandford had told me that a person with sight of greater than +/- 8 dioptres is regarded as clinically partially sighted. I doubt that such people frequently go out hunting without their spectacles.
134. Professor Rogers was then asked about the documentary prior art relied upon by Leica. In his original report, he had said that the "prior art does not really add much to the common general knowledge of the skilled person". Yet, when cross-examined, he tried to make an exception for the Mai pistol scope patent, which he had said in his first report did not "explain why the negative lens 18 was used" even though a skilled person "would understand its function". I did not find this part of Professor Rogers's evidence particularly impressive.
135. In relation to Naumann, Professor Rogers explained that it was a conjugate zoom or switched magnification system employing a negative lens in his position B just to the left of the second intermediate image. Even though Professor Rogers was not aware of the Naumann text before this case, it did inform the reader that the use of the negative lens increased eye relief and positively influenced the field curvature.
136. As to the position of the negative lens in Naumann, Professor Rogers accepted, as Dr Blandford had said, that the eyepiece system of lenses can be collected on the eyepiece side of the second intermediate image, but can, in some commercial usages (albeit not commonly), also extend just to the objective side of the second intermediate image.
137. Professor Rogers tried to suggest that the Betensky patent too was relevant to the design of riflescopes, even though it had a zoom mechanism in the eyepiece, provided eye relief of only 10 millimetres, and did not include an erecting system of lenses, but used prisms instead. He relied primarily upon the fact that Betensky taught clearly the idea of using a negative lens to reduce the cross section of the beam, allowing the skilled person to have a slimmer inverting means.
138. The following concluding exchange relating to the Betensky patent gave an insight into Professor Rogers's approach:-

Q. What I suggest to you, [P]rofessor, is what you are doing is taking again, with the [P]atent in mind, what you want to take from Betensky, jettisoning what you do not want to take, and reaching a conclusion which we say is not one a skilled person who did not have the [P]atent in mind would do.

A. Someone who had the problem presented and solved by the [P]atent in mind would use whatever techniques exist, and they would not have to be necessarily from the same application at all. If a technique works optically anyway, it does not necessarily have to be part of that group of instruments".

139. As regards the Mai pistol scope patent, Professor Rogers said that "[t]he patent is essentially a mechanical patent to do with a phenomenon called "trackout", which is a sideways shift of the image. The optical system is not even commented on. Clearly it is taken as a given, in other words, a fairly standard way of achieving an inverting zoom relay". He accepted that the Mai patent was "all about this concern he has of ensuring that the lenses, if I put it this way, are placed correctly and stay where they are put".
140. The Mai patent generated several exchanges of supplementary experts' reports directed at the strength of the negative lens (18) used on the objective side of the second intermediate image. Professor Rogers accepted that Mai taught nothing about the purpose of putting the negative lens in that position. But he nonetheless undertook complex calculations designed to show that the skilled person could ascertain the power of the negative lens from what was in the Mai patent and that he could use what was there to create a riflescope with far greater eye relief by changing the eyepiece. He denied that all that was wild thinking and said this:-

"Q. I think we will be submitting to my Lord that this is exactly wild thinking. Again, you are looking at this with one aim. You are reading Mai determined to try to get within the [P]atent.

A. It might seem so, but my approach is totally logical. Therefore it cannot be seen as contrived. I say take an existing unit and just change the eyepiece to convert it from one usage to another usage".

141. In my judgment, Professor Rogers's first thought was right – the Mai patent added little to the common general knowledge of the skilled person. I am afraid to say that much time was wasted on consideration of its details.
142. Finally, Professor Rogers was asked about the Nikon patent concerning an eyepiece with enhanced eye relief to assist spectacle users, where the negative lens (G21 on the diagram above) was some distance in front of the intermediate image (FS on the diagram above). He accepted it was about an eyepiece design to be used with an objective lens system. When it was put to him that Nikon was not directed to people interested in high zoom riflescopes, he said: "[i]t is not, I agree. It is directed towards somebody who wants a low Petzval Sum, better eye relief given by other equivalent systems, not riflescope, other equivalent systems, and also the idea of having the negative lens to the left (sic) of the intermediate image plane also gives a narrowing of the beam, what I call the waist effect. It may not be relevant in many systems, although it could. As in Betensky, you want to narrow the width of the beam going through, for example, a prismatic erecting system".
143. Overall, I did not find Professor Rogers's evidence as useful as his undoubted expertise could have made it. He was really somewhat too partisan. He looked at everything from the standpoint of the Patent, seeking to show how, once one knew about the Patent, one could get to it from a variety of different angles. The numerous elements of prior art that he relied upon was significant. They all had negative lenses, but none of them was using that negative lens in quite the same way as the Patent. It was a classic 'mosaicing' exercise. Professor Rogers seems to have thought that if the invention could be pieced together from several pieces of prior art, even if they were not part of the common general knowledge of the skilled person, that would be enough to defeat the Patent. As I shall shortly explain, that is not the law as I understand it. This deficiency in his understanding significantly depreciated the usefulness of his evidence. Moreover, Professor Rogers's undoubted eminence in his field seems to have made it difficult for him to see things from the point of view of the notional person skilled in the art. I gained far less help from his evidence as to how that person would behave, than I did from Dr Blandford's testimony.

The law

144. Before turning to deal with the issues, I shall seek to summarise the law in the various areas of contention between the parties. Ultimately, however, there was very little dispute as to the applicable legal principles. What divided the parties was, as so often happens, the application of those principles to the facts of this case.

Construction

145. Lord Hoffmann explained in Kirin-Amgen Inc v. Hoechst Marion Roussel Limited [2005] RPC 9 at paragraph 32 that construction is concerned with "what a reasonable person to whom the utterance was addressed would have understood the author to be using the words to mean". Jacob LJ giving the judgment of the Court of Appeal (sitting with Patten LJ and Kitchin J) in Virgin Atlantic Airways v. Premium Aircraft Interiors [2010] RPC 8 re-stated the principles set out by Lord Hoffmann at paragraph 5 as follows:-

"[5] One might have thought there was nothing more to say on this topic after Kirin-Amgen v Hoechst Marion Roussel [2005] RPC 9. The judge accurately set out the position, save that he used the old language of Art 69 EPC rather than that of the EPC 2000, a Convention now in force. The new language omits the terms of from art 69. No one suggested the amendment changes the meaning. We set out what the judge said, but using the language of the EPC 2000:

"182 The task for the court is to determine what the person skilled in the art would have understood the patentee to have been using the language of the claim to mean. The principles were summarised by Jacob LJ in Mayne Pharma v Pharmacia Italia [2005] EWCA Civ 137 and refined by Pumfrey J in Halliburton v Smith International [2005] EWHC 1623 (Pat) following their general approval by the House of Lords in Kirin-Amgen v Hoechst Marion Roussel [2005] RPC 9. An abbreviated version of them is as follows:

(i) The first overarching principle is that contained in Article 69 of the European Patent Convention;

(ii) Article 69 says that the extent of protection is determined by the claims. It goes on to say that the description and drawings shall be used to interpret the claims. In short the claims are to be construed in context.

(iii) It follows that the claims are to be construed purposively – the inventor's purpose being ascertained from the description and drawings.

(iv) It further follows that the claims must not be construed as if they stood alone – the drawings and description only being used to resolve any ambiguity. Purpose is vital to the construction of claims.

(v) When ascertaining the inventor's purpose, it must be remembered that he may have several purposes depending on the level of generality of his invention. Typically, for instance, an inventor may have one, generally more than one, specific embodiment as well as a generalised concept. But there is no presumption that the patentee necessarily intended the widest possible meaning consistent with his purpose be given to the words that he used: purpose and meaning are different.

(vi) Thus purpose is not the be-all and end-all. One is still at the end of the day concerned with the meaning of the language used. Hence the other extreme of the Protocol – a mere guideline – is also ruled out by Article 69 itself. It is the terms of the claims which delineate the patentee's territory.

(vii) It follows that if the patentee has included what is obviously a deliberate limitation in his claims, it must have a meaning. One cannot disregard obviously intentional elements.

(vii) It also follows that where a patentee has used a word or phrase which, acontextually, might have a particular meaning (narrow or wide) it does not necessarily have that meaning in context.

(vii) It further follows that there is no general 'doctrine of equivalents'.

(viii) On the other hand purposive construction can lead to the conclusion that a technically trivial or minor difference between an element of a claim and the corresponding element of the alleged infringement nonetheless falls within the meaning of the element when read purposively. This is not because there is a doctrine of equivalents: it is because that is the fair way to read the claim in context.

(ix) Finally purposive construction leads one to eschew the kind of meticulous verbal analysis which lawyers are too often tempted by their training to indulge".

Validity: Added matter

146. In European Central Bank v. Document Security Systems Incorporated [2008] EWCA Civ 192, the Court of Appeal (Jacob, Lloyd LJJ and Sir John Chadwick) summarised the legal principles as to the "added matter" objection as follows:-

"11. The legal provision is Art. 123(2) of the EPC transposed into UK law as s.72(1)(d) of the Patents Act 1977:

"The European patent application or European patent may not be amended in such a way that it contains subject-matter which extends beyond the content of the application as filed."

Breach of this rule is a ground of revocation.

12. Kitchin J summarised the legal principles for the application of this rule in a manner which was not challenged and which we accept is correct:

[96] The test for added matter was explained by Aldous J in Bonzel v Intervention Ltd [1991] R.P.C. 553 at 574:

"The decision as to whether there was an extension of disclosure must be made on a comparison of the two documents read through the eyes of a skilled addressee. The task of the Court is threefold:

(a) To ascertain through the eyes of the skilled addressee what is disclosed, both explicitly and implicitly in the application.

(b) To do the same in respect of the patent as granted.

(c) To compare the two disclosures and decide whether any subject matter relevant to the invention has been added whether by deletion or addition.

The comparison is strict in the sense that subject matter will be added unless such matter is clearly and unambiguously disclosed in the application either explicitly or implicitly."

[97] A number of points emerge from this formulation which have a particular bearing on the present case and merit a little elaboration. First, it requires the court to construe both the original application and specification to determine what they disclose. For this purpose the claims form part of the disclosure (s.130(3) of the Act), though clearly not everything which falls within the scope of the claims is necessarily disclosed.

[98] Second, it is the court which must carry out the exercise and it must do so through the eyes of the skilled addressee. Such a person will approach the documents with the benefit of the common general knowledge.

[99] Third, the two disclosures must be compared to see whether any subject matter relevant to the invention has been added. This comparison is a strict one. Subject matter will be added unless it is clearly and unambiguously disclosed in the application as filed.

…

[102] Sixth, it is important to avoid hindsight. Care must be taken to consider the disclosure of the application through the eyes of a skilled person who has not seen the amended specification and consequently does not know what he is looking for. This is particularly important were the subject matter is said to be implicitly disclosed in the original specification".

Validity: Novelty

147. Section 72(1)(a) of the Patents Act 1977 allows the court to revoke a patent if "the invention is not a patentable invention". Section 2(1) of the 1977 Act provides that "[a]n invention shall be taken to be new if it does not form part of the prior art", and section 2(2) provides that "[t]he state of the art … shall be taken to comprise all matter (whether a product, a process, information about either, or anything else) which has at any time before the priority date of that invention been made available to the public … by written or oral description, by use or in any other way". Section 2(3) provides that the state of the art in the case of an invention to which an application or a patent relates shall be taken to comprise matter contained in an application for another patent with an earlier priority date.
148. Lord Hoffmann explained in Synthon BV v. SmithKline Beecham plc [2006] RPC 10 at paragraphs 19-33 that the two requirements for anticipation of disclosure and enablement were distinct concepts, each of which had to be satisfied and each of which had its own rules. Thus the prior art in question must both disclose and enable the claimed invention. The matter relied upon as prior art must disclose subject matter which, if performed, would necessarily result in an infringement of the patent, and must enable the ordinary skilled person to perform the invention which satisfied the requirement of disclosure. Moreover, as Lord Hoffmann also explained, the test for novelty is strict and there must be clear and unambiguous disclosure which necessarily results in infringement of the claim.

Validity: Obviousness

149. Section 3 of the 1977 Act provides that "[a]n invention shall be taken to involve an inventive step if it is not obvious to a person skilled in the art, having regard to any matter which forms part of the state of the art by virtue only of section 2(2) above (and disregarding section 2(3)above)".
150. In Regeneron Pharmaceuticals Inc v. Genentech Inc [2013] EWCA Civ 93, Kitchin LJ reiterated at paragraphs 68-71 the correct approach to obviousness (citing first from his own decision in Generics (UK) Ltd v. H Lundbeck [2007] RPC 32 at paragraph 72, which was approved by the House of Lords in Conor v. Angiotech [2008] RPC 28 at paragraph 42) as follows:-

"The question of obviousness must be considered on the facts of each case. The court must consider the weight to be attached to any particular factor in the light of all the relevant circumstances. These may include such matters as the motive to find a solution to the problem the patent addresses, the number and extent of the possible avenues of research, the effort involved in pursuing them and the expectation of success".

151. Kitchin LJ then referred to Jacob LJ's judgment in Conor in the Court of Appeal [2007] RPC 20 at paragraph 45 as follows:-

"In the end the question is simply "was the invention obvious?". This involves taking into account a number of factors, for instance the attributes and cgk of the skilled man, the difference between what is claimed and the prior art, whether there is a motive provided or hinted by the prior art and so on. Some factors are more important than others. Sometimes commercial success can demonstrate that an idea was a good one. In others "obvious to try" may come into the assessment. But such a formula cannot itself necessarily provide the answer. Of particular importance is of course the nature of the invention itself".

152. The four-step approach set out in Windsurfing International Inc v. Tabur Marine (Great Britain) Ltd. [1985] RPC 59 and by the Court of Appeal in Pozzoli v. BDMO [2007] FSR 37, was also reiterated by Kitchin LJ in Regeneron at paragraph 70 as follows:-

"[1](a) Identify the notional 'person skilled in the art' (b) Identify the relevant common general knowledge of that person.

(2) Identify the inventive concept of the claim in question, or if that cannot readily be done, construe it;

(3) Identity what, if any, differences exist between the matter cited as forming part of the "state of the art" and the inventive concept of the claim or the claim as construed;

(4) Ask whether, when viewed without any knowledge of the alleged invention as claimed: do those differences constitute steps which would have been obvious to the person skilled in the art or do they require any degree of invention?"

153. In Technip France SA's Patent [2004] RPC 46, Jacob LJ (with whom Pill and Mummery LJJ agreed) explained the nature of the person skilled in the art at paragraphs 6-15 as follows:-

"6 The "man skilled in the art" is invoked at many critical points of patent law. The claims of a patent must be understood as if read by that notional man — in the hackneyed but convenient phrase, the "court must don the mantle of the skilled man". Likewise many questions of validity (obviousness, and sufficiency for instance) depend upon trying to view matters as he would see them. He indeed has statutory recognition — Arts 56, 83 and 100 of the EPC expressly refer to "the person skilled in the art".

7 It is settled that this man, if real, could be very boring—a nerd. Lord Reid put it this way in Technograph Printed Circuits Ltd v Mills & Rockley (Electronics) Ltd [1972] R.P.C. 346 at p.355:

"… the hypothetical addressee is a skilled technician who is well acquainted with workshop technique and who has carefully read the relevant literature. He is supposed to have an unlimited capacity to assimilate the contents of, it may be, scores of specifications but to be incapable of a scintilla of invention. When dealing with obviousness, unlike novelty, it is permissible to make a 'mosaic' out of the relevant documents, but it must be a mosaic which can be put together by an unimaginative man with no inventive capacity."

8 The no-mosaic rule makes him also very forgetful. He reads all the prior art, but unless it forms part of his background technical knowledge, having read (or learnt about) one piece of prior art, he forgets it before reading the next unless it can form an uninventive mosaic or there is a sufficient cross-reference that it is justified to read the documents as one.

9 He does, on the other hand, have a very good background technical knowledge—the so-called common general knowledge. Our courts have long set a standard for this which is set out in the oft-quoted passage from General Tire & Rubber Co v Firestone Tyre & Rubber Co Ltd [1972] R.P.C. 457 at 482 which in turn approves what was said by Luxmoore J. in British Acoustic Films Ltd v Nettlefold Productions (1936) 53 R.P.C. 221 at 250. For brevity I do not quote this in full — Luxmoore J.'s happy phrase "common stock of knowledge" conveys the flavour of what this notional man knows. Other countries within the European Patent Convention apply, so far as I understand matters, essentially the same standard.

10 The man can, in appropriate cases, be a team—an assembly of nerds of different basic skills, all unimaginative. But the skilled man is not a complete android, for it is also settled that he will share the common prejudices or conservatism which prevail in the art concerned.

11 None of the above is controversial. However, sometimes the requirement that the skilled man be uninventive is used by counsel for a patentee in an attempt to downgrade or dismiss the evidence of an expert called to say that a patent is obvious—"my witness is more nerdlike than his" is the general theme. I do not find this a helpful approach. It is frequently invoked and Mr Waugh Q.C. invoked it in this case in an effort to downgrade Rockwater's expert evidence on obviousness given by Professor Witz. Mr Waugh said his witness, Mr Nash, was more appropriately qualified than Professor Witz, and that the latter, because he had patents in his name, "was of an inventive turn of mind".

12 I must explain why I think the attempt to approximate real people to the notional man is not helpful. It is to do with the function of expert witnesses in patent actions. Their primary function is to educate the court in the technology—they come as teachers, as makers of the mantle for the court to don. For that purpose it does not matter whether they do not approximate to the skilled man. What matters is how good they are at explaining things.

13 But it also is permissible for an expert witness to opine on an "ultimate question" which is not one of law. I so held in Routestone Ltd v Minories Finance Ltd [1997] BCC 180 and see s.3 of the Civil Evidence Act 1972. As regards obviousness of a patent Sir Donald Nicholls V.C. giving the judgment of the Court of Appeal in Mölnlycke AB v Procter & Gamble Ltd (No.5) [1994] R.P.C. 49 at p.113 was explicit on the point:

"In applying the statutory criterion [ i.e. as to whether an alleged inventive step was obvious] and making these findings [ i.e. as to obviousness] the court will almost invariably require the assistance of expert evidence. The primary evidence will be that of properly qualified expert witnesses who will say whether or not in their opinions the relevant step would have been obvious to a skilled man having regard to the state of the art."

14 But just because the opinion is admissible, "it by no means follows that the court must follow it. On its own (unless uncontested) it would be 'a mere bit of empty rhetoric' Wigmore, Evidence (Chadbourn rev) para.1920. What really matters in most cases is the reasons given for the opinion. As a practical matter a well-constructed expert's report containing opinion evidence sets out the opinion and the reasons for it. If the reasons stand up the opinion does, if not, not. A rule of evidence which excludes this opinion serves no practical purpose. What happens if the evidence is regarded as inadmissible is that experts' reports simply try to creep up to the opinion without openly giving it. They insinuate rather than explicate" (Minories at p.188).

15 Because the expert's conclusion ( e.g. obvious or not), as such, although admissible, is of little value it does not really matter what the actual attributes of the real expert witness are. What matters are the reasons for his or her opinion. And those reasons do not depend on how closely the expert approximates to the skilled man".

154. Jacob LJ said this at paragraphs 112-3, and 122 in Technip France:-

"112 Nor were the well-known warnings against ex post facto analysis in dispute. Fletcher-Moulton L.J.'s judgment in British Westinghouse Electric & Manufacturing Co Ltd v Braulik (1910) 27 R.P.C. 209 is as true today as when it was first said:

"I confess that I view with suspicion arguments to the effect that a new combination, bringing with it new and important consequences in the shape of practical machines, is not an invention, because, when it has once been established, it is easy to show how it might be arrived at by starting from something known, and taking a series of apparently easy steps. This ex post facto analysis of invention is unfair to the inventors, and, in my opinion, it is not countenanced by English Patent Law."

113 Nor was there any dispute that normally when a judge has made a finding of obviousness, an appellate court should be slow to interfere, only doing so when the judge has made an error of principle—see above.

122 …All the "bits and pieces" of the invention were known separately for many years. The question "why was it not done before" is always a powerful consideration when considering obviousness, particularly when all the components of a combination have been long and widely known. Sometimes there is a good answer ...e.g. no demand, not worth the expense, prior art only recent). Apart from the no-demand-until-recently point, Mr Thorley only offered two other explanations. He suggested that the expense of building a vessel capable of carrying out the patented process was not warranted until shortly before the date of the patent. This fails for two reasons: first it is the no-demand point in another form, and secondly the expense is not all that great. Implicit in the argument is that a whole vessel would have to be specially constructed. But that is not so — existing vessels could be modified at the (for the oil industry) trivial expense of £3 million".

155. In KCI Licensing Inc. v. Smith & Nephew plc [2010] FSR 31, Arnold J explained the issues that should be noted about a plea of obviousness based on common general knowledge at paragraphs 105-112:-

"105 The classic modern exposition of the law as to what constitutes common general knowledge is contained in the following repeatedly-cited passage from the judgment of Aldous LJ, building on earlier authorities, in Beloit Technologies Inc v Valmet Paper Machinery Inc [1997] RPC 489 at 494–495:

"It has never been easy to differentiate between common general knowledge and that which is known by some. It has become particularly difficult with the modern ability to circulate and retrieve information. Employees of some companies, with the use of libraries and patent departments, will become aware of information soon after it is published in a whole variety of documents; whereas others, without such advantages, may never do so until that information is accepted generally and put into practice. The notional skilled addressee is the ordinary man who may not have the advantages that some employees of large companies may have. The information in a patent specification is addressed to such a man and must contain sufficient details for him to understand and apply the invention. It will only lack an inventive step if it is obvious to such a man.

It follows that evidence that a fact is known or even well-known to a witness does not establish that that fact forms part of the common general knowledge. Neither does it follow that it will form part of the common general knowledge if it is recorded in a document. As stated by the Court of Appeal in General Tire & Rubber Co. v. Firestone Tyre & Rubber Co. Ltd. [1972] R.P.C. 457, at page 482, line 33:

'The two classes of documents which call for consideration in relation to common general knowledge in the instant case were individual patent specifications and grave; widely read publications'.

As to the former, it is clear that individual patent specifications and their contents do not normally form part of the relevant common general knowledge, though there may be specifications which are so well known amongst those versed in the art that upon evidence of that state of affairs they form part of such knowledge, and also there may occasionally be particular industries (such as that of colour photography) in which the evidence may show that all specifications form part of the relevant knowledge.

As regards scientific papers generally, it was said by Luxmoore, J. in British Acoustic Films (53 R.P.C. 221 at 250): "In my judgment it is not sufficient to prove common general knowledge that a particular disclosure is made in an article, or series of articles, in a scientific journal, no matter how wide the circulation of that journal may be, in the absence of any evidence that the disclosure is accepted generally by those who are engaged in the art to which the disclosure relates. A piece of particular knowledge as disclosed in a scientific paper does not become common general knowledge merely because it is widely read, and still less because it is widely circulated. Such a piece of knowledge only becomes general knowledge when it is generally known and accepted without question by the bulk of those who are engaged in the particular art; in other words, when it becomes part of their common stock of knowledge relating to the art."

And a little later, distinguishing between what has been written and what has been used, he said:

"It is certainly difficult to appreciate how the use of something which has in fact never been used in a particular art can ever be held to be common general knowledge in the art."

Those passages have often been quoted, and there has not been cited to us any case in which they have been criticised. We accept them as correctly stating in general the law on this point, though reserving for further consideration whether the words "accepted without question" may not be putting the position rather high: for the purposes of this case we are disposed, without wishing to put forward any full definition, to substitute the words "generally regarded as a good basis for further action".'"

…

110 In the Court of Appeal in that case [2009] EWCA Civ 646, [2009] RPC 23 , Jacob LJ quoted the passage I have cited from Raychem and commented at [25]:

"Of course material readily and widely to hand can be and may be part of the common general knowledge of the skilled person – stuff he is taken to know in his head and which he will bring to bear on reading or learning of a particular piece of prior art. But there will be other material readily to hand which he will not carry in his head but which he will know he can find if he needs to do so (my emphasis). The whole passage is about material which the skilled man would refer to 'as a matter of course.' It by no means follows that the material should be taken to be known to the skilled man if he has no particular reason for referring to it."

111 He went on to quote what Kitchin J had said at first instance in the passage I have cited and observed at [27]:

"I agree with that although I personally do not find the point of principle 'subtle'. It would be wholly subversive of patents and quite unfair to inventors if one could simply say 'piece of information A is in the standard literature, so is B (albeit in a different place or context), so an invention consisting of putting A and B together cannot be inventive.' The skilled man reads each specific piece of prior art with his common general knowledge. If that makes the invention obvious, then it does. But he does not read a specific citation with another specific citation in mind, unless the first causes him to do so or both are part of the matter taken to be in his head."

156. In Ratiopharm GmbH v. Napp Pharmaceutical Holdings Ltd [2009] RPC 11, Floyd J said at paragraph 158 that one should exercise care, in dealing with pleas of obviousness, as follows:-

"… allegations of obviousness in the light of common general knowledge alone need to be treated with a certain amount of care. They can be favoured by parties attacking the patent because the starting point is not obviously encumbered with inconvenient details of the kind found in documentary disclosures, such as misleading directions or distracting context. It is vitally important to make sure that the whole picture presented by the common general knowledge is considered, and not a partial one".

157. In Schlumberger Holdings Limited v. Electromagntic Geoservices AS [2010] RPC 33, Jacob LJ (with whom Waller and Sullivan LJJ agreed) said this about the place of secondary evidence in considering the problem of obviousness at paragraphs 76-77 and 90-3:-

"76 In answering these questions it is also important to consider the secondary evidence. I shall go to the details of this in due course, but before I do so I should say something about secondary evidence generally.

77 It generally only comes into play when one is considering the question "if it was obvious, why was it not done before?" That question itself can have many answers showing it was nothing to do with the invention, for instance that the prior art said to make the invention obvious was only published shortly before the date of the patent, or that the practical implementation of the patent required other technical developments. But once all other reasons have been discounted and the problem is shown to have been long-standing and solved by the invention, secondary evidence can and often does, play an important role. If a useful development was, in hindsight, seemingly obvious for years and the apparently straightforward technical step from the prior art simply was not taken, then there is likely to have been an invention.

…

90 The plain fact is that there was no real explanation of why the idea was not taken up well before the date of the Patent. The simplest explanation – indeed the only one that fits the known facts – is that the inventors hit upon something which others had missed. Occam's razor points to invention.

91 Mr Thorley went further, suggesting that exploration geophysicists had a mind-set: thinking that CSEM was essentially an academic technique of no use to them, just as vacuum cleaner engineers were "bag-ridden" in the Dyson v Hoover case. I am not sure the analogy is quite perfect because in that case the invention involved doing away with something previously considered essential whereas the invention of the Patent involves doing something extra (a survey using CSEM after a seismic survey had found the target).

92 An alternative explanation from mind-set is that exploration geophysicists simply did not really articulate the problem or consider it possible it could be solved, they just accepted that once a possible target had been identified a well had to be sunk to find out whether it was hydrocarbon or brine/water.

93 I do not think it necessary to delve further into the topic of mind-set. The plain fact is that the patent is for a useful technique – one which the Judge held to be a "significant advance" [see 104] and which Mr Silverleaf concedes is useful. It could have been both proposed and used much earlier than it was. That points to invention".

See also Apimed Medical Honey Ltd v. Brightwake Ltd. [2012] RPC 17 per Kitchin LJ at paragraph 48.

158. Finally, Mr Hicks relied upon the dicta of Laddie J in Brugger v. Medic-Aid Limited [1996] R.P.C. 635 at pages 656-7 and 661 to the effect that if the patentee chooses to advance broad claims, the inventive concept will be broadened in an equivalent way, and that if a particular route is obvious, it is not any less obvious from a technical point of view merely because there are a number of obvious routes to take.

Validity: Insufficiency

159. Section 72(1)(c) of the 1977 Act allows the court to revoke a patent if "the specification of the patent does not disclose the invention clearly enough and completely enough for it to be performed by a person skilled in the art".
160. In Novartis AG, Cibavision AG v. Johnson & Johnson Medical Limited [2009] EWHC 1671 (Pat), Kitchin J explained the 2 principles involved in the plea of insufficiency at paragraphs 233 and 236 as follows:-

"232 It is a ground for revocation under section 72 of the Act (corresponding to Art 83 EPC ) that the specification does not disclose the invention in a manner sufficiently clear and complete for it to be performed by a person skilled in the art. The meaning of this requirement has attracted a good deal of judicial attention and certain principles of relevance to this case are now well established.

233 The first is that the specification must enable the invention to be performed to the full extent of the monopoly claimed. As Lord Hoffmann explained in the House of Lords in Biogen v Medeva [1977] RPC 1 at pages 48-49:

"In fact the Board in Genentech I/Polypeptide expression was doing no more than apply a principle of patent law which has long been established in the United Kingdom, namely, that the specification must enable the invention to be performed to the full extent of the monopoly claimed. If the invention discloses a principle capable of general application, the claims may be in correspondingly general terms. The patentee need not show that he has proved its application in every individual instance. On the other hand, if the claims include a number of discrete methods or products, the patentee must enable the invention to be performed in respect of each of them.

Thus if the patent has hit upon a new product which has a beneficial effect but cannot demonstrate that there is a common principle by which that effect will be shared by other products of the same class, he will be entitled to a patent for that product but not for the class, even though some may subsequently turn out to have the same beneficial effect: see May & Baker Ltd v. Boots Pure Drug Co. Ltd. (1950) 67 RPC 23 , 50. On the other hand, if he has disclosed a beneficial property which is common to the class, he will be entitled to a patent for all products of that class (assuming them to be new) even though he has not himself made more than one or two of them.

Since Genentech I/Polypeptide expression the EPO has several times reasserted the well established principles for what amounts to sufficiency of disclosure. In particular, in Exxon/Fuel Oils (T 409/91) [1994] O.J. EPO 653, paragraph 3.3, the Technical Board of Appeal said of the provision in the European Patent Convention equivalent to section 15(5)(c) of the Act:

"Furthermore, Article 84 EPC also requires that the claims must be supported by the description, in other words, it is the definition of the invention in the claims that needs support. In the Board's judgment, this requirement reflects the general legal principle that the extent of the patent monopoly, as defined by the claims, should correspond to the technical contribution to the art in order for it to be supported, or justified."" …

236 The second principle is that whether the specification discloses an invention clearly and completely enough for it to be performed by a person skilled in the art involves a question of degree. It is impossible to lay down any precise rule because the degree of clarity and completeness required will vary depending on the nature of the invention and of the art in which it is made. On the one hand, the specification need not set out every detail necessary for performance. The skilled person must be prepared to display a reasonable degree of skill and use the common general knowledge of the art in making routine trials and to correct obvious errors in the specification, if a means of correcting them can readily be found. Further, he may need to carry out ordinary methods of trial and error, which involve no inventive step and generally are necessary in applying the particular discovery to produce a practical result. On the other hand, he should not be required to carry out any prolonged research, enquiry or experiment: Mentor Corporation v Hollister Inc. [1993] RPC 7".

161. In the Court of Appeal, Jacob LJ (with whom Ward and Patten LJJ agreed) upheld Kitchin J and added this at paragraphs 72 and 74:-

"72 To my mind this is a long way off from satisfying the sufficiency test. As to that, there was no real dispute. The leading English case is Mentor v Hollister [1993] RPC 1 but I prefer to go to Board of Appeal authority. I only need to go to two cases. The first is Detergents/UNILEVER , T 0435/91. The Board laid down some principles:

2.2.1 … In the Board's judgment the criteria for determining the sufficiency of the disclosure are the same for all inventions, irrespective of the way in which they are defined, be it by way of structural terms of their technical features or by their function. In both cases the requirement of sufficient disclosure can only mean that the whole subject-matter that is defined in the claims, and not only a part of it, must be capable of being carried out by the skilled person without the burden of an undue amount of experimentation or the application of inventive ingenuity.

The peculiarity of the "functional" definition of a component of a composition of matter resides in the fact that this component is not characterised in structural terms, but by means of its effect. Thus this mode of definition does not relate to a tangible component or group of components, but comprises an indefinite and abstract host of possible alternatives, which may have quite different chemical compositions, as long as they achieve the desired result. Consequently, they must all be available to the skilled person if the definition, and the claim of which it forms a part, is to meet the requirements of Article 83 or 100(b) EPC . This approach is based on the general legal principle that the protection covered by a patent should correspond to the technical contribution to the art made by the disclosure of the invention described therein, which excludes that the patent monopoly be extended to subject-matter which, after reading the patent specification, would still not be at the disposal of the skilled person. …

There cannot, of course, be a clear-cut answer to the question of how many details in a specification are required in order to allow its reduction to practice within the comprehensive whole ambit of the claim, since this question can only be decided on the basis of the facts of each individual case. Nevertheless, it is clear that the available information must enable the skilled person to achieve the envisaged result within the whole ambit of the claim containing the respective "functional" definition without undue difficulty, and that therefore the description with or without the relevant common general knowledge must provide a fully self-sufficient technical concept as to how this result is to be achieved.

…

74 Mr Waugh accepted that this case summarised the law. The heart of the test is: "Can the skilled person readily perform the invention over the whole area claimed without undue burden and without needing inventive skill?"

162. With that introduction to the main applicable legal principles, I turn to deal with the issues that require determination.

Issues of construction

Issue 1: In integer 3 of claim 1, what is the proper meaning of a "central tube with a maximum external diameter of 35mm"?

Issue 2: In integer 4 of claim 1, what is the proper meaning of "the central tube contains an inverting system"?

163. These issues can be dealt with together. Integer 3 of claim 1 refers to a "central tube with a maximum external diameter of 35 millimetres". Integer 4 of claim 1 requires that the central tube "contains an inverting system". Leica contend that integers 3 and 4 of claim 1 require the whole of the inverting system to be contained in the central tube or at least in a portion of the central section not exceeding 35 millimetres, and that the embodiments shown in Figures 3a to 3c of the Patent are to be assumed to show that to be the case.
164. Against this background, the real issue between the parties is as to whether the negative lens shown as "2" in Figures 3a to 3c of the Patent must be contained within the part of the central tube not exceeding 35 millimetres in diameter. The question has an aura of absurd over-technicality and unreality about it, because it is intended to found an argument on infringement caused by the fact that Leica's riflescopes place their negative lens "F" within the flared section of tube, apparently between the inverting system and the eyepiece system (though still well to the left of the second intermediate image). Optically, the point is irrelevant.
165. The irony also is that most riflescopes seem to have a flared section of outer case between the inverting system and the eyepiece system – for aesthetic, if no other, reasons. Yet, Figures 3a to 3c in the Patent show the negative lens just at the start of the flared tube, and both these figures and the confidential product description of Leica's riflescopes seem to show the internal tube continuing around the negative lens even after the external case has started to flare. Paragraph 19 of the Patent makes clear that the dimension of 30-35 millimetres is an external one to be "without taking account of any adjusting turrets 8 or the like which might be provided".
166. Mr Hicks argued that a possible technical reason for the limitation he suggested was to exclude designs like Naumann in which the negative lens is close to the second intermediate image. I do not think that is the way that such designs were excluded. As a matter of construction of the Patent, read fairly as a whole by a skilled person, it is perfectly clear that in integrating the negative lens within the inverting system, it could not be on the second intermediate image. The experts agreed that the skilled person would know that the benefits of the Patent could not be obtained if the negative lens is placed too close to the second intermediate image. Figures 3a to 3c of the Patent show just that – a negative lens integrated into the inverting system some distance from the second intermediate image.
167. In my judgment, the claim fairly read does not require the whole of the inverting system to be fully within the central tube. As was said in Amgen and in Virgin supra, "the claims are to be construed purposively – the inventor's purpose being ascertained from the description and drawings" and "the claims must not be construed as if they stood alone – the drawings and description only being used to resolve any ambiguity". Adopting that approach, the negative lens is not, on a proper construction of the Patent, required to be wholly contained within the part of the central tube not exceeding 35 millimetres in diameter, but may be in a flared end of it. Optically, the negative lens must be integrated in the inverting system as integer 12 of claim 1 requires.
168. Thus, the words "central tube (6) with a maximum external diameter of 35mm" in integer 3 of claim 1, and the words "the central tube (6) contains an inverting system" in integer 4 of claim 1 signify that the inverting system must be predominantly but not wholly within the central tube with the maximum external diameter of 35 millimetres. The central tube houses the bulk of the inverting system, but the key point is that the negative lens is a part of that optical system or module, as integer 12 of claim 1 makes clear.

Issue 3: In integer 11 of claim 1, what is the proper meaning of "a maximum zoom greater than four times"? Is this integer so ambiguous as to have no meaning?

169. Once again, the Patent is to be construed as the skilled person would have understood it, not in an over-technical or unrealistic way.
170. The words "a maximum zoom greater than four times" in integer 11 of claim 1 must be construed in the context of the Patent as a whole. It is obviously not good English, and has been translated from the German. Leica point to paragraph 1 of the Description referring to "an adjustable optical magnification means with a more than fourfold magnification", and paragraph 15 referring to "a maximum magnification or a maximum zoom greater than four times" as demonstrating ambiguity or that the claims are limited to a system where the minimum magnification is 1x.
171. There are a number of reasons why Leica's approach is flawed. The technical person to whom the Patent is addressed would know that the field of view issues addressed by the Patent would be less likely to arise for a zoom riflescope between 1-4x to 1-6x. Moreover a fair reading of the Description as a whole makes it clear that the Patent is concerned with creating a riflescope with a zoom factor in excess of 4 (see particularly paragraphs 2-4 concerning the prior art). Moreover, Dr Blandford did not think that the words "a maximum zoom greater than four times" could mean "with a maximum magnification of more than four times".
172. The main problem for Leica, however, is the use of the word "zoom", which Dr Blandford defined as "[a] continuous user-controlled change in focal length or magnification which maintains focus and image quality over the entire range of lens movements". The word "change" is important. Without descending to a minute and unrealistic analysis, the word "zoom" connotes the change in magnification, and, therefore, the words "a maximum zoom greater than four times" must be taken to mean a change in magnification greater than 4 times, which can only sensibly be referring to the zoom factor.
173. In my judgment, it would be abundantly clear to the skilled person reading the patent fairly as a whole that integer 11 of claim 1 was referring to a zoom factor of greater than 4.

Issue 4: In integers 12 & 14 of claim 1, what is the proper meaning of "an optical beam deflector device integrated in the inverting system" and of "disposed on the end of the inverting system"?

174. Leica submit that there is doubt as to whether the Patent is suggesting that the negative lens 2 should be optically or mechanically integrated into the inverting system. This is an optical Patent. The inverting system is an optical system to invert and magnify the first intermediate image. I was impressed by Dr Blandford's evidence as to the modularity of such systems. He was quite clear that the skilled person would be looking to design each of an objective, inverting, and eyepiece lens system. There can be no real doubt, therefore, that integers 12-14 of claim 1 are speaking of a negative lens optically integrated into the inverting lens system. Since the inverting system exists so as optically to create the second intermediate image, the skilled person could have no doubt that the negative lens 2 was to be optically part of the inverting system and positioned before the second intermediate image. This is confirmed by paragraphs 15 and 16 of the Description, referring, first, to the negative lens "provided as an additional lens arrangement integrated in the inverting system", and secondly, that that negative lens could "equally well be mounted in the telescopic device as a separate component, separately from the inverting system 1". The latter possibility indicates that the central design is to include the negative lens in the inverting system.
175. It is well known, as I have said, that the inverting system is on the objective side of the second intermediate image. Thus, it is clear that under claim 1 the negative lens is to be positioned within the inverting system in front of the second intermediate image. Though Figures 3a to 3c show it some distance away from the second intermediate image, it is not clear from the Patent how far away it should be. That is because the skilled person would, as Professor Rogers accepted in evidence, be able to calculate the necessary measurements using a standard computer design system. The benefits of the enhanced subjective field of view would not be obtained, as I have already said, if the negative lens were too close to the second intermediate image, as the skilled person would also know.
176. Leica contend that integer 14 of claim 1 allows the negative lens to be on or on the eyepiece side of the second intermediate image. In my judgment, that is not the proper construction of the Patent. Paragraph 17 of the Description only contemplates the possibility of the negative lens being positioned "on the side of the eye-piece-end image plane 10 [i.e. the second intermediate image plane] facing away from the eyepiece 5". If it is facing away from the eyepiece and is on the side of the second intermediate image, it must be on the objective side of that image plane 10. It is true, however, that paragraph 17 contemplates the negative lens coming close to the second intermediate image, which is less clear from integer 14 of claim 1 which requires it to be on the end of the inverting system.
177. The difference between Claims 1 and 3, however, explains this apparent discrepancy. Claim 3 broadly mirrors the words used in the last sentence of paragraph 17, and is, as it seems to be, envisaging a different position closer to the second intermediate image than claim 1, but not on it or on the eyepiece side of it.
178. I therefore conclude that the words "an optical beam deflector device integrated in the inverting system" and "disposed on the end of the inverting system" in integers 12 & 14 of claim 1 contemplate a negative lens positioned at the end of the inverting system, but still as part of it, some way to the objective side of second intermediate image.

Issue 5: In integer 16 of claim 1, what is the proper meaning of "at least 22º is guaranteed for all magnifications"?

179. This construction issue has puzzled me more than most. The words used in integer 16 of claim 1 seem to me to be entirely clear. They are "so that a subjective field of view ... of the telescopic device of at least 22º is guaranteed for all magnifications …". These words would mean to a skilled person (and indeed any other person) that the subjective field of view will be at least 22 degrees whatever the magnification at which the device is being used. I cannot sensibly see any other meaning. Leica argue, based on a construct of Professor Rogers, that "all that is required is that the various components and their positions (as well as the mechanical aspects of the system) are designed in such a way that this field of view will be achieved". I cannot agree. The point of the teaching in the Patent appears to be that a wide field of view will be achieved at all magnifications, since it is well known that subjective field of view declines at low magnifications.
180. The complex series of figures advanced in evidence as to the subjective field of view of the IOR riflescope served to show that it did not fulfil the requirements of the Patent as to field of view.

Issue 6: What is the proper meaning of claim 2?

181. Claim 2 is not independently valid over claim 1. It refers to the "magnification of the magnification optics of the inverting system" being at least fivefold and preferably sixfold. Leica cast doubt on the meaning of the cited words. As for claim 1, these words are, in my judgment, in the context of the Patent Description and the details in claim 1, clearly referring to a zoom factor of at least 5 and preferably 6.

Issue 7: Does claim 3 add anything to integers 12 & 14 of claim 1?

182. Claim 3 is, as I have already said, an alternative to claim 1, in that it contemplates the negative lens being positioned on the objective side of the second intermediate image plane.

Issue 8: In claim 6, what is the proper meaning of "the inverting system"?

183. The inverting system is the same as claimed in claims 1 to 5, and includes the negative lens.

Issues of infringement

Issue 9: Do Leica's riflescopes have a central tube containing the inverting system which meets the requirements of integer 4 of claim 1 and the requirements for a central tube with a maximum external diameter of 35mm in integer 3 of claim 1?

184. I have already dealt, in effect, with this issue under issues 1 and 2 above. I have no doubt that each of Leica's riflescopes have a central tube which meets the requirement for a central tube with a maximum external diameter of 35 millimetres in integer 3 of claim 1. The fact that the negative lens in Leica's riflescopes is in the flared end of the central tube does not prevent it being part of the inverting system and being contained within the central tube within the proper meaning of the Patent.

Issue 10: Do the magnification optics of Leica's riflescopes satisfy the requirements of claim 2?

185. Leica accepts that, if integer 2 of claim 2 is to be interpreted as referring to zoom factors (as I have held), then Leica's riflescopes satisfy the requirements of claim 2.

Issue 11: Do Leica's riflescopes have an "inverting system" of the focal length specified in claim 6?

186. It is accepted that, since the inverting system in the Patent includes the negative lens, the inverting systems of Leica's riflescopes including negative lens F have a total focal length less than the 11 millimetres specified in claim 6.

Added matter

Issue 12: Was the feature of integers 5 and 9 of claim 1 stated to be "when at least one of the optical elements (3a, 3b) of the inverting system is displaced" disclosed in the application as filed?

187. Claim 4 of the "Patent Claims" in the application as filed referred to an inverting system which had "at least two optical elements (3a, 3b), preferably lens arrangements, which can be moved relative to one another". Leica suggests that these words do not encompass the possibility that one of the lenses in the inverting system can remain stationery, which is contemplated by integers 5 and 9 of claim 1. I accept that integers 5 and 9 include the possibility of one of the lenses in the inverting system remaining stationery, even though Dr Blandford accepted that both lenses have to move for a functioning smooth zoom relay system.
188. In accordance with the principles I have set out from European Central Bank supra, I have to construe both the application and the Patent to see what is disclosed, bearing in mind that not everything that is covered is necessarily disclosed.
189. It seems to me that, in construing the application, there are a number of possibilities if two lenses "can be moved relative to one another". One of them is that both can move, but another is that one remains stationery at some time or all times whilst the other moves. The movement referred to is "relative" to the other lens. Even the stationery lens moves "relative" to the other, since it will, observed from the viewpoint of that other lens, have "moved" so as to be closer to it or further away from it. Mr Hicks accepted these propositions, but said that reading the application as a whole, it did not disclose the movement of one of the two lenses only, and that the skilled person would not regard it as so doing. He relied on the fact that Dr Blandford accepted that both lenses had to move in a zoom system. I take the view that the skilled person would think that the application disclosed the possible movement of only one lens, without hindsight. The fact that one lens moving might be unlikely to create a satisfactory smooth zoom relay system does not affect the clear meaning of the words used in claim 4 of the application.

Novelty

Issue 13: Did the IOR riflescope sold to Realex in Finland in February 2005 clearly and unambiguously disclose all the features of the claimed invention, in particular (a) a maximum zoom greater than four times (integer 11); (b) an optical beam deflector device integrated in the inverting system and disposed on the end of the inverting system facing the eyepiece (integers 12 & 14); (c) a subjective field of view of at least 22º guaranteed for all magnifications (integer 16); and (d) an optical beam deflector device disposed on the side of an eyepiece end image plane pointing away from the eyepiece (claim 3 & 8)?

190. As explained above, the test for novelty is strict. Leica's case is that none of the claims in the Patent is novel over the IOR riflescope. Leica point to the four elements identified in this issue.
191. As for the first element, it is true that the IOR riflescope had a zoom factor greater than 4, as envisaged by integer 11 of claim 1.
192. As for the second element, the IOR riflescope has its negative lens immediately to the eyepiece side of the second intermediate image, as I have indicated above and Professor Rogers agreed. The IOR riflescope had its negative lens in Professor Rogers's position B, whilst claim 1 of the Patent teaches placing the negative lens in position C. On no analysis was the negative lens in the IOR riflescope "integrated in the inverting system" and "disposed on the end of the inverting system facing the eyepiece" as in integers 12 & 14 of claim 1.
193. As for the third element, it is true that the IOR riflescope has a powerful negative lens within the strengths identified in integer 15 of claim 1 of the Patent. But, as I have construed integer 16 of claim 1 of the Patent, the IOR riflescope does not "guarantee" a subjective field of view of at least 22º for all magnifications. The evidence was clear that, in normal usage, the IOR riflescope fell below 22 degrees at minimum magnification and at 3.45x magnification. It was only when the instrument was adjusted to allow for unlikely usage by someone with (most unusual – even improbable) uncorrected long sight in excess of +5 dioptres that it demonstrated a subjective field of view in excess of 22 degrees at all magnifications. That cannot be regarded as clearly and unambiguously disclosing this feature of claim 1 of the Patent.
194. As for the fourth element, I have already held that claim 3 of the Patent teaches placing the negative lens in position B on the objective side of the second intermediate image. It is true that, in extreme conditions, it has been shown that the second intermediate image of the IOR riflescope can move to the eyepiece side of the negative lens, thus placing the negative lens on the objective side of the second intermediate image. But in my judgment, that fact does not mean that the IOR riflescope discloses subject matter that would necessarily result in an infringement of the Patent, since the normal usage of the IOR riflescope would result in the negative lens being to the eyepiece side of the second intermediate image and the reticle as it was designed to be. The IOR riflescope did not clearly and unambiguously disclose this feature of claims 3 and 8 of the Patent.

Obviousness and Inventive Step

Issue 14: Was the claimed invention obvious over the common general knowledge alone in July 2005?

195. This is probably the key issue in this case.
196. The first question is as to the state of riflescope technology in July 2005. Much time was spent at the trial and with the experts looking at various brochures for riflescopes available in 2005. As was shown by the cross-examination of Professor Rogers, the bulk of commercially available riflescopes in 2005 had a zoom factor of 4 or less, and their design was largely unchanged from 1990. Manufacturers generally adopted a strikingly consistent approach towards lens positioning. Those widely available riflescopes as at July 2005 which had a negative lens at all tended to have it in the eyepiece lens system some way to the right of the second intermediate image. Four pre-2005 riflescopes from Kassner, Zeiss, Hakko and Seeadler had negative lenses in the eyepiece close to the second intermediate image. Only the 1978 Weaver Scope appeared to have a weak negative lens in Professor Rogers's position C, a short distance to the left of the second intermediate image. I shall return to what was common general knowledge about these riflescopes below.
197. There was, as I have said, agreement between the parties as to the identity and attributes of the relevant person skilled in the art for the purposes of common general knowledge and obviousness. They would be an optical systems designer with a first degree in physics or a related subject, and perhaps a second degree in optics and some years design experience.
198. The parties also largely agreed the matters that were common general knowledge by July 2005. Taking those matters from the closing submissions, I find the following to be relevant common general knowledge:-

i) The overall layout of the optical design of a telescope or riflescope of this kind including objective, relay and eyepiece lenses.

ii) The functionality of the sub-systems and the modular approach to design of the system as a whole.

iii) The fact that the lenses of the eyepiece system could be placed either side of the second intermediate image in order to correct and present the final image to the eye.

iv) The fact that the relay or inverting system was always placed on the objective side of the second intermediate image in order to invert and magnify that image.

v) The Petzval Sum is a measure of field curvature and that any lens system with predominantly positive lenses will inevitably exhibit some field curvature.

vi) The human eye can accommodate a degree of field curvature. The lower the degree of field curvature the better the user experience, because lower curvature avoids or reduces the need to re-focus or the time taken by the eye to re-focus.

vii) An optical design has a certain working field of view. Once the design is complete, the designer specifies where to place the field stop and what size the field stop should be.

viii) There were a number of known ways of reducing or ameliorating field curvature, including:-

a) introducing astigmatism, although there is a limit to how useful that can be;

b) scaling up the size of the instrument, although that is not practical for a riflescope as it would make the instrument too wide and/or too long and/or too heavy;

c) introducing a field stop, so as to mask field curvature (not to reduce it); and

d) adding a negative lens into the system.

ix) By far the most common position for a negative lens surface in commercial riflescopes by July 2005 was in the eyepiece on the eyepiece side of the second intermediate image.

x) A negative lens used to reduce field curvature had to have some separation from the positive lenses.

xi) Eyepieces were also known which included negative lenses at the second intermediate image (or just either side to avoid dust being visible) – but not generally in riflescopes.

xii) Reticles were placed at an intermediate image. With higher zoom scopes the preference was to place the reticle at the second intermediate image.

xiii) Most zoom riflescopes available as at July 2005 had a zoom ratio of 4 or less, had a central tube with external diameter of maximum 35 millimetres, required eye relief of between 80-90 millimetres to allow for recoil, and exhibited a subjective field of view of between 17 and 23 degrees (average of around 20 degrees).

xiv) Most pistol scopes available as at July 2005 had lower zoom ratios than riflescopes (and maximum magnifications of 8x or 10x), had smaller external diameter central tubes, required eye relief of about 280-450 millimetres, and exhibited a subjective field of view of less than 10 degrees.

xv) A wide subjective field of view at all magnifications in a zoom riflescope was always desirable, and high zoom factors were also likely to be desirable.

xvi) Given a set of design parameters and having decided on the layout of the lens systems and what was to be achieved, a skilled designer could then evaluate and optimise the design using a software program such as Zemax, which had been available for many years prior to July 2005. Zemax is only as good as the data provided to it; the software alone is not enough.

xvii) The riflescopes shown in the brochures to which I have referred above represented what was commonly done in the art in terms of optical design in the 1990's and early 2000's.

xviii) A zoom relay telescope having the general optical arrangement shown in Figure 1 of the Patent and illustrated in a number of the brochures.

xix) None of the prior art relied upon nor the Weaver-Scope of 1978 nor any individual scope were part of the common general knowledge in July 2005.

199. Before making a formal application of Pozzoli tests 3 and 4, it is important to understand what divided the parties on this crucial issue of obviousness over the common general knowledge.
200. Leica's argument was that a skilled person faced with the problem of creating a telescope with a zoom factor above 4 with a field of view of above 22 degrees at all magnifications would run immediately into the problem of field curvature, and would set about solving that problem – if not that problem alone, then certainly that as the major problem. In doing so, the skilled person would find it obvious to use a strong negative lens positioned at one of Professor Rogers's positions A, B or C. Leica say they do not have to show that one or other of these positions was more obvious – the fact that there was a range of options that were obvious does not affect the validity of their point. Accordingly, the only inventive concepts of the Patent that needs to be considered, according to Leica, are (i) the inclusion of a negative lens, and (b) the position of the negative lens between the inverting system and the second intermediate image. Professor Rogers and Dr Blandford broadly agreed that a skilled person would consider using a strong negative lens to solve the problem of field curvature, and that positions A, B and C were obvious places to put that lens for that purpose. Dr Blandford did not think he would have put the lens, even on that basis, at position C, but Leica did not think that to be of any great significance.
201. Swarovski, on the other hand, argues that the inventive concept is the whole of the claim in the Patent and, therefore, includes (abbreviating matters somewhat) creating a telescope with a central tube of not more than 35 millimeters diameter containing an inverting system, with an integrated negative lens of between -20 and -40 dioptres, with a zoom factor greater than 4 and a subjective field of view of at least 22 degrees at all magnifications. On this basis, one should start from the widely available riflescopes as at July 2005. And none of those had a strong negative lens integrated into the inverting system. In short, as Mr Lykiardopoulos put the matter: "Mr Hicks has to show why something that was self-evident to all, was done by none". It is only, says Swarovski, when one starts from trying to solve the problem of field curvature, which Dr Blandford did not think was a real problem at all, that you can stand a chance of showing that the use of a strong negative lens in position C was obvious.
202. I put to Mr Lykiardopoulos in reply that the case he had to meet was that both experts thought that it was obvious to a skilled person to use a negative lens to deal with (a) the high Petzval Sum caused by the use of more powerful positive lenses in the inverting system needed to create a greater magnification than 4, and (b) the required greater subjective field of view. I asked why, if that were right, it was not obvious to a skilled person to put that negative lens in one of positions A, B or C.
203. Mr Lykiardopoulos's answer was to say, in essence that this was looking at the wrong question through the wrong end of the telescope (if the pun can be forgiven). Even though I had framed the question deliberately avoiding reference to field curvature, one only started from that position by mis-identifying the task of the skilled person addressing the problem that the Patent set out to solve. If one correctly identified the whole of the Patent's claim 1 (as I have sought to summarise it above), the skilled person is asking himself the entirely different question of how, starting from the accepted design of riflescopes in July 2005 and the common general knowledge summarised above, one could obtain a higher zoom factor and a greater subjective field of view. The skilled person would assume that any negative lens would be placed in the eyepiece module as had always been done before. He would not even consider placing a negative lens somewhere never seen before – i.e. in the inverting system.
204. Mr Lykiardopoulos might also have answered that it was not actually common ground between the experts that it was part of the skilled person's common general knowledge to introduce a negative lens to increase the subjective field of view, though Dr Blandford knew that a negative lens would have this effect. As it seems to me, ultimately, this may not much matter.
205. The third Pozzoli test requires the identification of the differences between the common general knowledge and the inventive concept of the claim. Here, the parties diverge considerably as I have said. In my judgment, the differences between the common general knowledge and the inventive concept of the claim in the Patent were creating a telescope with a central tube of not more than 35 millimetres diameter containing an inverting system with an integrated negative lens of between -20 and -40 dioptres, with a zoom factor greater than 4 and a subjective field of view of at least 22 degrees at all magnifications. The difference is not simply the insertion of a negative lens in position C as Leica contended. That is because the inventive concept includes all the essentials of the Patent.
206. The fourth Pozzoli test then asks whether those differences would have been obvious to the skilled person or whether they require any degree of invention. It is important here to exclude any knowledge of the Patent and any hindsight. Posed in this way, and viewed particularly against the state of the art in designing riflescopes in July 2005, the question becomes rather more straightforward. Was it common general knowledge to achieve the desired improved zoom factor (over 4) and subjective field of view (over 22 degrees at all magnifications) to integrate a strong negative lens between -20 and -40 dioptres in the inverting system. Nobody had done this before, and I am satisfied that it was not obvious to the skilled person to do so. I accept Dr Blandford's evidence that he would not have thought of doing it. It would only be obvious if the matter were viewed as Professor Rogers viewed it. In my judgment, as Swarovski submitted, his approach was to ask the wrong question. The question is not whether one might use a negative lens in that position to solve the problem of field curvature. I accept Dr Blandford's evidence that field curvature would not have been regarded as such a problem by the skilled person. It was well known that the human eye had considerable accommodation of at least 2 dioptres, and Professor Rogers's idea that the skilled person would have been looking to create a riflescope with field curvature of only 0.5 dioptres is wholly unsupported. In my judgment, it is simply wrong. Optical designers would have accepted an element of discomfort caused by field curvature – knowing that the human eye would be able to re-focus given a short amount of time and accommodate the differences between the sagittal and tangential images.
207. The reality is that insertion of a strong negative lens integrated in the inverting system would not have been an obvious way of creating the parameters of the Patent.
208. This conclusion is, in my judgment, confirmed by such secondary evidence as was available. The designs of riflescopes had remained the same for many years. Optical designers were a conservative group. It is true, as Leica submitted, that no great demand for high zoom factor or high subjective field of view riflescopes was shown. But it is obvious that there would be some demand for telescopes and riflescopes with higher zoom factors. They had probably not previously been produced because of the problem of length, width and weight described by the experts. The solution suggested by the Patent was in my judgment, inventive and not at all obvious.

Issue 15: Was the claimed invention obvious over the IOR riflescope, taken together with the common general knowledge?

209. This is a far more simple question than it seemed in argument. The IOR riflescope had its negative lens in Professor Rogers's position B slightly to the eyepiece side of the second intermediate image. The IOR riflescope did not suggest the solution taught by the Patent of integrating a strong negative lens in the inverting lens system.
210. It was not suggested to Dr Blandford or in argument that it was obvious to modify the IOR scope so as to fall within the claims in the Patent. Why would a skilled person do so, since it seems that the IOR riflescope was regarded as a successful product? It was not suggested that the IOR riflescope's more limited subjective field of view at low magnifications was a problem that the skilled person would regard it as obvious to solve, or indeed that it could be solved.
211. The difference between the IOR riflescope and the inventive concept of the Patent is creating a telescope with its central tube containing an inverting system with an integrated negative lens of between -20 and -40 dioptres with a zoom factor greater than 4 and a subjective field of view of at least 22 degrees at all magnifications. Making the necessary alterations to the IOR riflescope would be far from obvious to the skilled person for the reasons I have already given.

Issue 16: Was the claimed invention obvious in the light of the teaching of Naumann, taken together with the common general knowledge?

212. Naumann was a textbook of which neither Dr Blandford nor Professor Rogers had previously heard. Though it concerned a switched magnification system, rather than a smooth zoom magnification system, the experts agreed that this made no material difference to the optical arrangement specified.
213. The simple reason why Naumann does not, in my judgment, render the Patent obvious is that the negative lens in Naumann (albeit that it may be a strong one) is in Professor Rogers's position B, close to the second intermediate image and forming part of the eyepiece lens system. It is true that the negative lens is on the objective side, but that did not put it in the same category as the positioning of the negative lens taught by the Patent on its proper construction. Naumann's teaching explains that the negative lens will improve eye relief and field curvature – both of which are anyway common general knowledge of the skilled person.
214. The difference between the teaching in Naumann and the inventive concept of the Patent is creating a telescope with its central tube containing an inverting system with an integrated negative lens of between -20 and -40 dioptres with a zoom factor greater than 4 and a subjective field of view of at least 22 degrees at all magnifications. Using the Naumann configuration in the design of a telescope would be far from obvious to the skilled person, and would not anyway lead to the invention in the Patent.

Issue 17: Was the claimed invention obvious in the light of the teaching of Betensky, taken together with the common general knowledge?

215. Betensky was probably the closest prior art relied upon, in that Betensky undoubtedly shows the negative lens in position C between the prism inverting system and the intermediate image. But Betensky teaches a method of creating an eyepiece zoom for binoculars, which is a very different thing, as Dr Blandford explained, from a zoom telescope or zoom riflescope. Dr Blandford complained that there was only one intermediate image in Betensky, and there was therefore nowhere to put the reticle. That is because Betensky simply did not concern a sighting scope of the type envisaged by the Patent.
216. It is true that Betensky teaches that a strong negative lens can be used to create the "waist effect", to correct off axis aberrations and to improve eye relief (albeit to only 10 millimetres). It mentions that the negative lens can be used independently of the other aspects of the invention. But, in my judgment, rather as Dr Blandford indicated, no skilled person without inventive capability would think that the negative lens used in Betensky had anything to do with the problem that he was facing. It is a patent concerned with an eyepiece zoom, which is miles away from a riflescope.
217. The difference between the teaching in Betensky and the inventive concept of the Patent is creating a telescope with its central tube containing an inverting system with an integrated negative lens of between -20 and -40 dioptres with a zoom factor greater than 4 and a subjective field of view of at least 22 degrees at all magnifications. The negative lens, though in the right position, is not integrated in the inverting system in Betensky. How could it be, when the inverting system there is made up of prisms? Using the negative lens from Betensky in the design of a telescope would be far from obvious to the skilled person, and would not lead to the invention in the Patent, because the negative lens is not integrated in the inverting system.
218. Accordingly, in my judgment, the claimed invention was not obvious in the light of the teaching of Betensky, taken together with the common general knowledge.

Issue 18: Was the claimed invention obvious in light of the teaching of Mai, taken together with the common general knowledge?

219. Somewhat remarkably, Mai assumed a disproportionate importance in the experts' reports and the argument. That was perhaps because the (strong) negative lens there was also in position C between the inverting system and the second intermediate image. But Mai was a mechanical patent for pistol scopes relating to the solution of a problem called "trackout" caused by the misalignment of lenses.
220. Mr Hicks relies on Dr Blandford's evidence that a skilled person would realise that the position of the negative lens in Mai had all the advantages of position C identified by Professor Rogers "within limitations". Mr Hicks's written closing then concludes: "Dr Blandford therefore accepted that if a skilled person would not automatically appreciate the advantages (and disadvantages) of a lens in position C in a zoom relay system, Mai would have provided that information". This epitomises the difference between the approaches of the parties. The Pozzoli tests do not require a comparison between the prior art and any single feature of the claimed invention. They require a comparison between the prior art and the entire inventive concept claimed.
221. Here, therefore, the proper comparison is between the teaching in Mai that a negative lens in position C may (for no given reason) be used in a pistol scope, and the inventive concept of the Patent in creating a telescope with its central tube containing an inverting system with an integrated negative lens of between -20 and -40 dioptres with a zoom factor greater than 4 and a subjective field of view of at least 22 degrees at all magnifications. The two are poles apart. It is, in my judgment, inconceivable that the skilled person would have regarded Mai as making it obvious that he should reach the invention in the Patent. He would simply have regarded Mai as irrelevant and nothing to do with what he was trying to achieve. Mai teaches a method of avoiding the mechanical problem of trackout, and no skilled person without inventive capability would think that the negative lens used in Mai had anything to do with the optical systems in a telescope or riflescope at all.
222. For these reasons, in my judgment, the claimed invention was not obvious in the light of the teaching of Mai, taken together with the common general knowledge.

Issue 19: Was the claimed invention obvious in light of the teaching of Nikon, taken together with the common general knowledge?

223. Mr Hicks ultimately accepted that Nikon added nothing to the other pieces of prior art. Accordingly, I do not need to consider it further.

Sufficiency

Issue 20: Does the Patent contain sufficient information, taken together with the common general knowledge, to enable a skilled person to perform the invention?

224. Leica have raised two matters under this heading. First, Leica contended that the words of integer 11 in claim 1 "a maximum zoom greater than four times" were ambiguous. I have already decided under issue 3 that they are not, read in the context of the Patent as a whole. Secondly, Leica contend that the Patent is deficient in information so that it does not enable a skilled person to perform the invention. Mr Hicks submits, and I accept, that if a claim lacks clarity so that it does not merely have a fuzzy boundary, but so that it is not possible to know what is intended at all, then the claim is invalid for insufficiency.
225. I accept that the Patent is, as I have already said, rather general in nature. There are very few figures or specifications included within it. But despite these lacunae, Professor Rogers's evidence was that, starting from one of the riflescopes that were widely available in July 2005, the skilled person could have created a riflescope meeting the Patent's requirements. In these circumstances, the argument as to insufficiency falls away.
226. In my judgment, the Patent contains sufficient information, taken together with the common general knowledge, to enable a skilled person to perform the invention.

Issue 21: Is integer 11 of claim 1 so ambiguous as to render the Patent insufficient?

227. For the reasons I have given under issue 3, I do not think that integer 11 of claim 1 is so ambiguous as to render the Patent insufficient. It clearly refers, in my judgment, to a zoom factor greater than 4.

Conclusions

228. As appears from my treatment of the issues above, I have concluded that Leica's challenges to the validity of the Patent fail. I have also found that Leica's riflescopes infringe the Patent.
229. It may be that the findings that I have made demonstrate the obviousness of claim 3 of the Patent from the IOR riflescope, but I will hear further argument on that point and also as to the consequences of my other findings, the relief to be granted, and as to costs.