GB2121211A - Athermal infrared objective lens systems - Google Patents
Athermal infrared objective lens systems Download PDFInfo
- Publication number
- GB2121211A GB2121211A GB08315030A GB8315030A GB2121211A GB 2121211 A GB2121211 A GB 2121211A GB 08315030 A GB08315030 A GB 08315030A GB 8315030 A GB8315030 A GB 8315030A GB 2121211 A GB2121211 A GB 2121211A
- Authority
- GB
- United Kingdom
- Prior art keywords
- lens
- primary
- powered
- objective lens
- thermal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000000463 material Substances 0.000 claims abstract description 38
- 230000004075 alteration Effects 0.000 claims abstract description 29
- 230000005855 radiation Effects 0.000 claims abstract description 16
- 229910052732 germanium Inorganic materials 0.000 claims abstract description 12
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims abstract description 12
- 210000001747 pupil Anatomy 0.000 claims abstract description 12
- 230000003287 optical effect Effects 0.000 claims abstract description 9
- PFNQVRZLDWYSCW-UHFFFAOYSA-N (fluoren-9-ylideneamino) n-naphthalen-1-ylcarbamate Chemical compound C12=CC=CC=C2C2=CC=CC=C2C1=NOC(=O)NC1=CC=CC2=CC=CC=C12 PFNQVRZLDWYSCW-UHFFFAOYSA-N 0.000 claims abstract description 3
- WBFMCDAQUDITAS-UHFFFAOYSA-N arsenic triselenide Chemical compound [Se]=[As][Se][As]=[Se] WBFMCDAQUDITAS-UHFFFAOYSA-N 0.000 claims abstract 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 9
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- 239000004411 aluminium Substances 0.000 claims description 9
- 238000006073 displacement reaction Methods 0.000 claims description 7
- 229910017000 As2Se3 Inorganic materials 0.000 description 6
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 230000008542 thermal sensitivity Effects 0.000 description 2
- 229910004613 CdTe Inorganic materials 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 229910001374 Invar Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/14—Optical objectives specially designed for the purposes specified below for use with infrared or ultraviolet radiation
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Toxicology (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
Abstract
An infrared objective lens system (15) comprises a primary (13) spaced from a secondary (14) on a common support assembly (16) and aligned on a common optical axis (10) and arranged to form a real image (9) at an external image surface from infrared radiation entering the system (15) through a pupil O in object space (11). Primary (13) is self-compensated for chromatic aberrations, is positively powered and is made of material the refractive index of which is relatively temperature insensitive such as arsenic triselenide and/or zinc selenide. The secondary (14) is positively powered, introduces minimal chromatic aberrations and is formed by a positively powered lens (C) and a negatively powered lens (D). Lens (C) is made of material the refractive index of which is relatively temperature insensitive such as arsenic triselenide. Lens (D) is made of a material the refractive index of which is relatively temperature sensitive such as germanium and the thermal aberration introduced by lens (D) is arranged to compensate for thermal aberrations introduced by the primary (13) and secondary (14) caused by thermal expansion of the support assembly (16) as a result of which the system (15) is rendered substantially passively athermal. <IMAGE>
Description
SPECIFICATION
Infrared objective lens systems
This invention relates to infrared objective lens systems for delivering infrared radiation to a radiation detecting system.
The arrival of high performance infrared radiation detectors has led to a demand for a high performance objective lens system, and a number of designs have been developed where the objective system resolution is diffraction limited.
One requirement imposed on the system is that it is substantially free from chromatic abberrations.
This is usually achieved in the known systems by making the principal lens of the system, if not all the lenses of the system, from germanium because germanium inherently has a very low value of dispersion coefficient and accordingly inherently introduces very low levels of chromatic aberration.
Another requirement imposed on the system is that it is substantially free from thermal aberrations, that is that its design resolution is maintained over a wide range of temperatures to which the system could be subjected when in use. Unfortunately the refractive index of germanium, in comparison to most other infrared materials, is very highly temperature sensitive so that although germanium is attractive for elimination of chromatic aberrations it poses considerable problems for thermal aberration elimination. In the known system thermal aberration compensation is achieved by utilising a complex assembly for supporting the lenses in a manner such that the displacement of the lenses caused by thermal expansion of the support assembly is complementary to the changes in optical characteristics of the lenses throughout the temperature range.Such an assembly is mechanically complex and detracts from the overall compactness and simplicity of the system.
It is an object of the present invention to provide an improved form of infrared objective system for delivering infrared radiation to a radiation detecting system in which the foregoing disadvantages are obviated or mitigated.
According to the present invention there is provided an infrared objective lens system for delivering infrared radiation to a radiation detecting system, said objective lens system comprising a primary and a secondary mounted in spaced apart relationship on a common support assembly and aligned on a common optical axis, wherein the primary is arranged to accept infrared radiation from a pupil, the secondary is arranged to accept radiation from the primary and to form a real image thereof at an external image surface, and primary being substantially self-compensated for chromatic aberrations, positively powered and made of material the refractive index of which is relatively temperature insensitive, the secondary is positively powered, introduces minimal chromatic aberrations, and is formed by a positively powered lens made of material the refractive index of which is relatively temperature insensitive and a negatively powered lens made of material the refractive index of which is relatively temperature sensitive, the arrangement being such that the thermal aberrations introduced by the primary and relative displacements of the primary and secondary caused by thermal expansion of the support assembly are compensated by thermal aberration introduced by said negatively powered lens so that the objective system is rendered substantiallv passively athermal.
The primary may comprise more than one lens element in which case chromatic aberration compensation is achieved by utilising two different materials for the lens elements in a manner known per se. In such an arrangement the refractive surfaces of the lens elements are preferably spherical or planar and the materials used may be selected from those numbered 2-9 in Table VII hereof.
Alternatively, the primary may comprise only a single lens element in which case chromatic aberration compensation is achieved by selection of the lens material but since there is the requirement that the material refractive index has relatively low thermal sensitivity this can only be achieved with currently known materials by using diamond. In this case the lens element may have an aspheric surface to compensate for substantially monochromatic aberrations introduced by a window having zero or very low optical power and through which the radiation is transmitted prior to refraction by the primary lens.
The secondary may comprise only two lens elements of which the positively powered element is made of a material which introduces colour aberrations but because such aberrations are determined in part by the optical power, in part by the aperture and in part by the dispersive coefficient of the material they can be kept to a minimum level at which their effect on the system performance as a whole is negligible. The material of this lens element may be selected from those numbered 2-9 in Table VII hereof.The negatively powered lens element of the secondary is preferably germanium which is inherently free of chromatic aberration but because of its negative power and the fact that its refractive index is relatively thermally sensitive the thermal aberration introduced, which is a function of power and refractive index thermal coefficient, can be designed to compensate for the thermal aberrations introduced to the objective system by the primary and by the other lens element(s) of the secondary and by the lens displacements introduced by thermal expansion of the support assembly.
It will be appreciated that thermal sensitivity of refractive index is effective to affect the focal length of a lens element.
Preferably the lens support assembly is primarily made of a single material such as aluminium or stainless steel or invar. It will be appreciated that aluminium has a relatively large coefficient of thermal expansion but virtue of the optical design of the system according to the present invention the lens displacement introduced by aluminium can be compensated. This arises because of the very considerable compensation available from the negative-powered lens of the secondary especially when this lens is made of germanium. Accordingly, the lens support assembly can be as mechanically simple as is practical.
By virtue of the present invention the external image surface of the objective system remains substantially in one position in space over a wide range of temperatures and accordingly when a detecting system is located at that image surface the resolution of the objective system is maintained substantially constant. It is to be noted however that where the objective system of the present invention is to be utilised with a detecting system that itself is subject to displacement caused by thermal expansion of its own support the thermal compensation available within the objective system is sufficient to permit variation in position of the image surface so as to compensate for movement of the detecting surface of the detecting system. Furthermore the image surface can be designed to be flat or curved which for the attachment of different detecting systems can be advantageous.Near diffraction limited resolution can be achieved and in certain designs of objective system all refractive surfaces can be made spherical and of sufficiently large radius of curvature that simultaneous bulk manufacture of
lens elements is practical.
An embodiment of the present invention will now be described by way of example with reference to the accompanying schematic drawing and accompanying tables.
As is shown in the drawing an objective system 1 5 is formed by a primary 13 and a secondary 14 aligned on a common optical axis 10. The objective system 15 is of the focal refractor type and accepts bundles of parallel rays over the field of view from an entrance pupil q) formed in object space 11 and produces bundles of convergent rays over the field of view which form an image 9 in image space 12.
The primary 13 is formed by a positively powered lens element A and a negatively powered lens element B, the two elements together forming a doublet and providing low chromatic aberrations. The secondary 14 is formed by a positively powered lens element C and a negatively powered lens element
D each of which, together, and in particular lens element D, produce low chromatic aberrations, lens element D being made of a material which has a significantly greater thermal coefficient of refractive index than those materials which make lens elements A, B and C.
The lens elements A, B, C and D have respective refractive surfaces 1, 2; 3, 4; 5, 6 and 7, 8. The refractive surfaces 1, 2, 3, 4, 5, 6, 7 and 8 are each substantially spherical, i.e. if they are not truly spherical they are 'spherical' with the meaning of the art. The optical power of and the spacing between the various lens elements A, B, C and D is arranged such that the real image 9 is proximal refractive surface 8 and is external to the objective system 1 5.
The lens elements A, B, C and D are supported in position by a support assembly 16 shown schematically but which is primarily made of a single material and free from complex thermal compensating components.
The four lens elements A, B, C, D which together form the objective system 1 5 are made from at
least three different materials, the positively powered lens element C may be made from the same material as that of either the positively (A) or the negatively (B) powered lens element of the primary 13.
The negatively powered lens element (D) is made from a material which in comparison to the materials which make the other three lens elements A, B, C has lower dispersion and a high thermal coefficient of refractive index.
The relative position of the two lens elements in each of the primary and secondary 13, 14 is incidental i.e. they may be interchanged in position if so desired so that, for example, primary 1 3 has element B adjacent the pupil (D.
The two positive lens elements A, C can be made from any of the materials recited in Table VII excluding germanium, the preferabie materials being numbers 2-9 inclusive. The negative element B can also be made from any of these materials excluding germanium, the preferable materials being numbers 10 and 11 in Table VII. Germanium is unsuitable for use in lens elements A or B because of its high thermal coefficient of refractive index, but because of this fact and its low dispersion it is ideal for use in the negatively powered lens element D.
It will be noted that the materials so far discussed have been for use in the 8-1 3 micron waveband, however these and other materials are available which can provide similar properties in the 3-5 micron waveband.
The system 1 5 is fixed focus but any one lens element or combination of lens elements can be axially moved to accommodate targets in object space at different distances. This does not affect the thermal compensation but does require introduction of active mechanics in support assembly 1 6.
By way of a specific example, the system 1 5 may be manufactured with lens elements A and C
made of BSA (number 4 in Table Viz), lens element B made of Zinc Selenide (number 10 in Table VII) and lens element D made of germanium (number 1 in Table VII). In this case the system parameters
are set forth in Tables -VI hereof of which Tables I and II are particular to a temperature of +200C, Tables III and IV are particular to a temperature of +800C, and Tables V and VI are particular to a
temperature of -400C. All lens elements are supported by an assembly 16 made of aluminium.
It will be seen from Tables I to VI that at the best focus the system at +800C and -400C is out of focus by only -15 microns and +13 microns respectively in relation to the focus at +200C, the negative and positive defocus signs indicating that the objective system 1 5 per se is slightly overcompensated for thermal effects. Such 'defocussing' of the objective system 1 5 per se is sufficient to compensate for the variation in position of the detecting surface of a known form of detecting system arising from thermal expansion of the detecting system itself.A support assembly material of higher thermal expansion coefficient than aluminium could correct the objective system 1 5 per se totally for this or the optics could be slightly re-optimised without changing the lens materials if a totally compensated objective system were required.
The objective system 15 detailed has an effective focal length of 51 mm, accommodates a total diagonal field of 50 and produces convergent cones of rays operating at f/1.5 which is highly suitable for many detectors.
The objective system of Tables 1-VI is one of a family of systems which can be scaled for effective focal length (being the length denoted EFL in the drawing), aperture, field and f number. In each case the system produces very little distortion and there is no vignetting. The object space pupil can vary in position either away from primary 13 or into the air gap between primary 13 and secondary 14 depending on the tolerable resolution degradation which is considered acceptable.
TABLE I
Radius of Aperture
Item Surface Separation Curvature Material Diameter
Pupil* O Flat Air 35.00
1 0 57.24 Air 35.24
A
2 3.250 209.89 As2Se3 (BSA) 34.79
3 0.750 589.38 Air 34.57
B
4 1.250 99.97 ZnSe 33.73
5 50.000 27.46 Air 16.38
C
6 2.500 342.17 As2Se3(BSA) 15.68
7 0.500 531.15 Air 14.86
D
8 1.250 59.23 Ge 14.28
Images Image
Plane 9 14.015 Flat Air Diameter
4.4 * Maximum field angle at entrance pupil = 5 .
XAt best focus averaged over the maximum field.
All aluminium supporting structure where each lens element and image plane are connected in series at the maximum aperture diameter.
All data given at 200C.
TABLE II
Approximate R.M.S. Spot Sizes at Image Plane* (in microns)
Monochromatic at sPolychromatic over
Field (maximum = 50) 10.0 microns 8.0-12.0 microns
Axial 1.8 3.1
1/2 3.2 6.8 6.4 10.5
Full 11.4 15.6 * At best focus averaged over the field.
given as an equally weighted three wavelength accumulated measurement, the wavelengths being 8.0, 10.0 and 12.0 microns.
All data given at 200C.
TABLE Ill
Radius of Aperture
item Surface Separation Curvature Material Diameter Pupil* 0 Flat Air 35.00 1 0.008 57.32 Air 35.24
A
2 3.254 210.17 As2Se3(BSA) 34.79
3 0.753 589.66 Air 34.57
B
4 1.251 100.02 ZnSe 33.73
5 50.074 27.49 Air 16.34
C
6 2.503 342.63 As2Se3(BSA) 15.63
7 0.504 531.35 Air 14.81
D
8 1.250 59.25 Ge 14.23
Image Image
Planes 9 14.000 Flat Air Diameter
4.4
* Maximum field angle at entrance pupil = 5 .
(9At best focus averaged over the maximum field.
All aluminium supporting structure where each lens element and image plane are connected in series at
the maximum aperture diameter.
All data given at 800C.
TABLE IV
Approximate R.M.S. Spot Sizes at Image Plane* (in microns)
Monochromatic at G > Polychromatic over
Field (maximum = 50) 10.0 microns 8.0-12.0 microns
Axial 1.5 3.1 of 2.9 6.7 we 6.2 10.4
Full 11.1 15.5 * At best focus averaged over the field.
*Given as an equally weighted three wavelength accumulated measurement, the wavelengths being 8.0, 10.0 and 12.0 microns.
All data given at 800C.
TABLEV Radius of Aperture
Item Surface Separation Curvature Material Diameter
Pupil* O Flat Air 35.00
1 -0.008 57.17 Air 35.24
A
2 3.246 209.61 As2Se3(BSA) 34.79
3 0.747 589.10 Air 34.58
B
4 1.249 99.93 ZnSe 33.74
5 49.925 27.42 Air 16.42
C
6 2.497 341.72 As2Se3(BSA) 15.72
7 0.496 530.96 Air 14.92
D
8 1.250 59.21 Ge 14.33
Image Image
Planes 9 14.028 Flat Air Diameter
4.4 * Maximum field angle at entrance pupil = 50.
* At best focus averaged over the maximum field.
All aluminium supporting structure where each lens element and image plane are connected in series at
the maximum aperture diameter.
All data given at -400C.
TABLE VI
Approximate R.M.S. Spot Sizes at Image Plane* (in microns)
Monochromatic at EPolychromatic over
Field (maximum = 50) 10.0 microns 8.0-12.0 microns
Axial 2.5 3.4
3.7 7.0 9 6.8 10.7
Full 11.8 15.9 * At best focus averaged over the field.
Given as an equally weighted three wavelength accumulated measurement, the wavelengths being
8.0, 10.0 and 12.0 microns.
All data given at-400C.
TABLE VII
Refractive Thermal Thermal
Index at Primary Coefficient Coefficient
10.0 Coefficient of Expansion of Refractive Materials microns of Dispersiorss x 107/OC Index x 107/OC 1 Ge 4.0032 0.00187 61 3960 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
2 GaAs 3.27789 0.01067 57
3 B52 2.85632 0.00503 - - 4 BSA 2.77880 0.00568 220 740
5 CdTe 2.67517 0.00544 50 951
6 TI 1173 2.60037 0.00772 158 790
7 AMTIRI 2.49748 0.00589 130 850
8 BS1 2.49143 0.00670 128 700
9 T120 2.49166 0.00679 133 719 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ . ~ ~ ~ ~ ~ ~ ~ ~ ~
10 ZnSe 2.40652 0.01216 78 520
11 ZnS 2.20030 0.02651 68 463 * Over the wavelength range 8.0-12.0 microns
All data approximate and given at approximately 200 C.
Claims (8)
1. An infrared objective lens system for delivering infrared radiation to a radiation detecting system, said objective lens system comprising a primary and a secondary mounted in spaced apart relationship on a common support assembly and aligned on a common optical axis, wherein the primary is arranged to accept infrared radiation from a pupil, the secondary is arranged to accept radiation from the primary and to form a real image thereof at an external image surface, the primary being substantially self-compensated for chromatic aberrations, positively powered, and made of material the refractive index of which is relatively temperature insensitive, the secondary is positively powered, introduces minimal chromatic aberrations, and is formed by a positively powered lens made of material the refractive index of which is relatively temperature insensitive and a negatively powered lens made of material the refractive index of which is relatively temperature sensitive, the arrangement being such
that thermal aberrations introduced by the primary and relative displacements of the primary and
secondary caused by thermal expansion of the support assembly are compensated by thermal
aberration introduced by said negatively powered lens so that the objective system is rendered
substantially passively athermal.
2. An objective lens system as claimed in claim 1, wherein said primary is formed by two lens
elements closely spaced and forming a doublet.
3. An objective lens system as claimed in claim 2, wherein said doublet is formed by an arsenic
triselenide (BSA) lens element and a zinc selenide lens element.
4. An objective lens system as claimed in any preceding claim, wherein said positively powered
lens is formed by a single lens element and said negatively powered lens is formed by a single lens
element.
5. An objective lens system as claimed in claim 4, wherein said positively powered lens is formed by an arsenic triselenide (BSA) lens element, and said negatively powered lens is formed by a
germanium lens element.
6. An objective lens system as claimed in any preceding claim, wherein said common support
assembly is made of aluminium.
7. An objective lens system as claimed in claim 1 and as set forth in Tables I-V hereof.
8. An objective lens system as claimed in claim 1 in combination with a radiation detecting system
having a detecting surface located at said real image and wherein the combination is rendered
substantially passively athermal by selecting the degree of thermal aberration introduced by said
negatively powered lens to compensate for thermal aberrations introduced by the primary, relative
displacements of the primary and secondary caused by thermal expansion of the common support
assembly and thermal expansion of the detecting system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08315030A GB2121211B (en) | 1982-06-02 | 1983-06-01 | Athermal infrared objective lens systems |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8216035 | 1982-06-02 | ||
| GB08315030A GB2121211B (en) | 1982-06-02 | 1983-06-01 | Athermal infrared objective lens systems |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8315030D0 GB8315030D0 (en) | 1983-07-06 |
| GB2121211A true GB2121211A (en) | 1983-12-14 |
| GB2121211B GB2121211B (en) | 1985-12-18 |
Family
ID=26283011
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08315030A Expired GB2121211B (en) | 1982-06-02 | 1983-06-01 | Athermal infrared objective lens systems |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2121211B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2161616A (en) * | 1984-07-14 | 1986-01-15 | Pilkington Perkin Elmer Ltd | Optically athermal infra-red lenses |
| GB2194072A (en) * | 1986-04-03 | 1988-02-24 | Pilkington Perkin Elmer Ltd | Athermalised optical beam expander |
| US4827130A (en) * | 1987-10-22 | 1989-05-02 | General Electric Company | Selectable field infrared imager and lens set |
| FR2667695A1 (en) * | 1990-10-09 | 1992-04-10 | Thomson Trt Defense | OPTICAL ATHERMALIZATION OBJECTIVE SYSTEM. |
| US5331622A (en) * | 1991-05-28 | 1994-07-19 | Applied Magnetics Corporation | Compact optical head |
| US5568315A (en) * | 1991-05-28 | 1996-10-22 | Discovision Associates | Optical beamsplitter |
| WO2013098180A1 (en) | 2011-12-29 | 2013-07-04 | Umicore | Compact achromatic and passive athermalized telephoto lens arrangement |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB561503A (en) * | 1942-08-11 | 1944-05-23 | Combined Optical Ind Ltd | Improvements in optical systems using plastic lenses |
| GB1013156A (en) * | 1961-08-21 | 1965-12-15 | Eastman Kodak Co | Improvements in or relating to the manufacture of optical elements of zinc selenide |
| GB1280441A (en) * | 1970-01-06 | 1972-07-05 | Barr & Stroud Ltd | Improvements in or relating to horizon sighting sensors |
| GB2071353A (en) * | 1980-03-05 | 1981-09-16 | Barr & Stroud Ltd | Telescope objective system |
-
1983
- 1983-06-01 GB GB08315030A patent/GB2121211B/en not_active Expired
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB561503A (en) * | 1942-08-11 | 1944-05-23 | Combined Optical Ind Ltd | Improvements in optical systems using plastic lenses |
| GB1013156A (en) * | 1961-08-21 | 1965-12-15 | Eastman Kodak Co | Improvements in or relating to the manufacture of optical elements of zinc selenide |
| GB1280441A (en) * | 1970-01-06 | 1972-07-05 | Barr & Stroud Ltd | Improvements in or relating to horizon sighting sensors |
| GB2071353A (en) * | 1980-03-05 | 1981-09-16 | Barr & Stroud Ltd | Telescope objective system |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2161616A (en) * | 1984-07-14 | 1986-01-15 | Pilkington Perkin Elmer Ltd | Optically athermal infra-red lenses |
| EP0171903A1 (en) * | 1984-07-14 | 1986-02-19 | Pilkington P.E. Limited | Improvements in or relating to infra-red lenses |
| US4679891A (en) * | 1984-07-14 | 1987-07-14 | Pilkington P.E. Limited | Infra-red lenses |
| GB2194072B (en) * | 1986-04-03 | 1990-03-21 | Pilkington Perkin Elmer Ltd | Athermalised optical beam expander |
| US4834472A (en) * | 1986-04-03 | 1989-05-30 | Pilkington P.E. Limited | Optical beam expanders with materials chosen to effect athermalization |
| GB2194072A (en) * | 1986-04-03 | 1988-02-24 | Pilkington Perkin Elmer Ltd | Athermalised optical beam expander |
| US4827130A (en) * | 1987-10-22 | 1989-05-02 | General Electric Company | Selectable field infrared imager and lens set |
| FR2667695A1 (en) * | 1990-10-09 | 1992-04-10 | Thomson Trt Defense | OPTICAL ATHERMALIZATION OBJECTIVE SYSTEM. |
| EP0480805A1 (en) * | 1990-10-09 | 1992-04-15 | Thomson-Trt Defense | Objective systems with optical temperature compensation |
| US5202792A (en) * | 1990-10-09 | 1993-04-13 | Thomson Trt Defense | Systems of objectives with optical athermalization |
| US5331622A (en) * | 1991-05-28 | 1994-07-19 | Applied Magnetics Corporation | Compact optical head |
| US5568315A (en) * | 1991-05-28 | 1996-10-22 | Discovision Associates | Optical beamsplitter |
| US5646778A (en) * | 1991-05-28 | 1997-07-08 | Discovision Associates | Optical beamsplitter |
| WO2013098180A1 (en) | 2011-12-29 | 2013-07-04 | Umicore | Compact achromatic and passive athermalized telephoto lens arrangement |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2121211B (en) | 1985-12-18 |
| GB8315030D0 (en) | 1983-07-06 |
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