IL175236A - Single optical element and its use - Google Patents
Single optical element and its useInfo
- Publication number
- IL175236A IL175236A IL175236A IL17523606A IL175236A IL 175236 A IL175236 A IL 175236A IL 175236 A IL175236 A IL 175236A IL 17523606 A IL17523606 A IL 17523606A IL 175236 A IL175236 A IL 175236A
- Authority
- IL
- Israel
- Prior art keywords
- optical element
- single optical
- schmidt
- mirror
- inner region
- Prior art date
Links
- 230000003287 optical effect Effects 0.000 title claims description 143
- 239000000463 material Substances 0.000 claims description 15
- 230000005855 radiation Effects 0.000 claims description 9
- 230000003595 spectral effect Effects 0.000 claims description 9
- 230000000694 effects Effects 0.000 claims description 7
- 230000002093 peripheral effect Effects 0.000 claims 3
- 230000005540 biological transmission Effects 0.000 claims 1
- 238000003384 imaging method Methods 0.000 description 38
- 230000004075 alteration Effects 0.000 description 11
- 239000011247 coating layer Substances 0.000 description 8
- 230000009471 action Effects 0.000 description 7
- 229910052732 germanium Inorganic materials 0.000 description 6
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 4
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- 238000007516 diamond turning Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000007493 shaping process Methods 0.000 description 3
- 238000011144 upstream manufacturing Methods 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000005083 Zinc sulfide Substances 0.000 description 2
- 230000006735 deficit Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 210000003128 head Anatomy 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 210000001747 pupil Anatomy 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000001931 thermography Methods 0.000 description 2
- DRDVZXDWVBGGMH-UHFFFAOYSA-N zinc;sulfide Chemical compound [S-2].[Zn+2] DRDVZXDWVBGGMH-UHFFFAOYSA-N 0.000 description 2
- 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 description 1
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- 230000001771 impaired effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
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Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/08—Catadioptric systems
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/08—Catadioptric systems
- G02B17/0804—Catadioptric systems using two curved mirrors
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/08—Catadioptric systems
- G02B17/0852—Catadioptric systems having a field corrector only
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/08—Catadioptric systems
- G02B17/0856—Catadioptric systems comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/08—Catadioptric systems
- G02B17/0884—Catadioptric systems having a pupil corrector
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
Description
175236 i?'Ji I 453489 rnn SINGLE OPTICAL ELEMENT AND ITS USE Pearl Cohen Zedek Latzer P-8644-IL 175236/2 Single optical element and its use The invention relates to a single optical element and its use.
Classical Schmidt systems comprise a spherical primary mirror at whose centre of curvature a so-called Schmidt correction plate is arranged. The image plane is located in this case between the primary mirror and the Schmidt correction plate. The Schmidt correction plate can be pulled forward in Schmidt systems having an aspheric primary mirror. This Schmidt correction plate serves the purpose of eliminating the spherical aberration of the primary mirror. The spherical aberration is manifested in the case of light rays which are incident near the edge of the primary mirror. These light rays are focused at a different distance than light rays incident in the middle. The negative result of this is a slightly blurry image whose imaging quality is frequently not sufficient for numerous applications - such as, for example, detecting targets by means of a homing head of a guided missile. It is therefore mandatory in such cases to introduce the Schmidt correction plate mentioned above.
Moreover, Schmidt systems have a large image field curvature as matter of principle (because of their primary mirror). Given this spherical aberration, the focal points for all the objects lie not in a plane, but on an inwardly curved spherical surface. The result is blurring which rises towards the edge of the image. This impairment of the imaging quality is, in turn, intolerable for many applications. The aberration of the image field curvature can be reduced by introducing a lens in the vicinity of the image plane.
A further disadvantage of a Schmidt system consists in that it has a very large overall length and an image plane which is difficult to access because of its position between the Schmidt correction plate and primary mirror. Consequently, it is not possible to use a Schmidt system, for example, for homing heads for guided missiles, in which only a restricted installation space is available. A small optics with an image field plane which is easily accessible can be implemented by redesigning the Schmidt system as a Schmidt-Cassegrain system by introducing a secondary mirror which guides the beam path reflected by the primary mirror out of the latter via a central opening therein. However, this requires the additional provision of a beam-folding element, the secondary mirror.
Thus, in order to obtain an imaging optics such as a Schmidt system or a Schmidt-Cassegrain system with imaging properties of high quality, there is a need for a number of optical elements such as a Schmidt correction plate, an image field flattening lens or a secondary mirror. These elements must be adjusted as exactly as possible in relation both to one another and to the primary mirror in order to ensure good imaging properties. Specifically for the holders of the elements, it must be ensured that said elements do not cause any problems with reference to scattered light and point image function.
It is a disadvantage that the optical elements and their holders for the most part cannot be produced from the same material. This frequently renders necessary an active temperature compensation of these optical elements in order to maintain a constant imaging quality even in the event of temperature fluctuations which may act on the imaging optics.
It is therefore the object of the present invention to specify a single optical element which largely renders superfluous a complicated adjustment of optical elements for correcting aberrations in an imaging optics, as well as an active temperature compensation of these optical elements.
It is also an object of the invention to specify a technical use of such a single optical element.
The first-named object is achieved by means of a single optical element having a principal direction of passage from an entrance side in the direction of an exit side and which is fashioned according to the invention as a Schmidt correction plate, as an image field flattening lens and as a reflecting mirror.
In a first step, the invention proceeds from the knowledge that a single optical element which combines three different optical elements in itself renders superfluous at least two optical elements for aberration correction or for beam folding. It is no longer necessary to adjust the optical elements relative to one another because of this saving in optical elements and the reduction to a single optical element. Such a single optical element can therefore exclude impairments of the optical imaging quality of imaging optics which are based on a maladjustment of optical elements relative to one another. The outlay on adjustment is reduced here to the alignment of the single optical element in relation to its associated imaging optics.
In a next step, the invention proceeds from the knowledge that an active temperature compensation is usually required for imaging optics which are exposed to larger temperature fluctuations when in use. Since the optical elements for beam folding or for correction of aberrations mostly consist of different materials, their temperature-dependent refractive index, and thus their image behaviour depend to a different extent on such temperature fluctuations. Again, the holders of the optical elements, which mostly consist of a different material from the optical elements themselves can have a lasting influence on the negative effect of temperature fluctuations on the refractive index or the imaging behaviour. A reduction in the optical elements required to a minimum in the form of a single optical element by means of which a number of optical elements can be replaced eases the problem of an impaired imaging behaviour on the basis of the different temperature-dependent changes in refractive index of optical elements and their associated holders which consist of different materials.
It is presently possible on the basis of modern fabrication techniques such as diamond turning to produce a complex single optical element which is fashioned as a Schmidt correction plate, as an image field flattening lens and as a mirror.
A single optical element reduces negative influences of sources of error which impair the imaging behaviour such as, for example, the maladjustment of different optical elements counter to one another, or the variously strong changes in refractive index, caused by temperature fluctuations, of the optical elements fabricated from different materials. Such a reduction ensures a better imaging behaviour as is of crucial importance for some applications - such as an imaging optics for target-tracking missiles, for example.
Moreover, it is possible to save costs, weight and installation space when use is made of a single optical element which combines a number of optical elements in itself, as against the use of a number of optical elements which serve only one function in each case.
A beam path falling onto a single optical element having a principal direction of passage from an entrance side in the direction of an exit side experiences the mode of operation of a Schmidt correction plate, that is to say the beam path is already influenced such that no difference in imaging behaviour results when the beam path subsequently falls onto the edge or the middle region of a primary mirror and is reflected by the latter. If a beam path reflected in such a way then strikes the single optical element again, the latter now ensures, by also being designed as an image field flattening lens and a reflecting mirror, that the focal point for all objects from which a beam path emanates lies in a plane and not, as otherwise, on an inwardly curved surface or, in other words, that the blurring rising towards the edge of the image is reduced, and that the beam path is retroreflected anew in the direction of the primary mirror in the principal direction of passage.
The single optical element expediently has a flat entrance side. As a result, the optical power of the single optical element with reference to its configuration as a Schmidt correction plate is independent of its thickness. This permits relatively large tolerances in the fabrication of the single optical element - such as by diamond turning on a CNC machine, for example. If, over and above this, the single optical element is to form the termination of an optical system with reference to the surroundings, its thickness can be adapted to the mechanical or thermal requirements of the respective use scenario under which the optical system is to be used.
The exit side of the single optical element is advantageously aspherically shaped. Here, aspheric means that the surface of the exit side can also have various aspheric regions. With the aid of such an aspheric surface, it is possible to introduce into an imaging system carefully controlled aberrations which can, for example eliminate the aberration of other optical elements in targeted fashion. The optical performance of an imaging optics can thereby be improved.
The single optical element is expediently cylindrical, and thus has a circular edge configuration. The cylindrical shaping facilitates the integration of the single optical element into an imaging optics, since most optical elements such as, for example, lenses have a circular cross sectional surface. It is possible by suitably selecting the linear magnification and arranging the optical elements with reference to the single optical element to ensure that a beam path which enters an imaging optics also leaves the imaging optics again and is not lost unintentionally because the geometrical dimensions of the optical elements are unfavourable selected. It is thereby ensured that no relevant optical image information to be expected for a beam path is falsified on passing through an imaging optics or does not arrive at all.
In a further advantageous refinement, the entrance side of the single optical element has a mirror coating in a central inner region. A beam path which strikes the exit side of the single optical element in a fashion opposing the principal direction of passage now either passes through this or - if it strikes the mirror-coated central inner region of the entrance side -is retroreflected by it and thereby runs in the principal direction of passage again. Owing to this refinement, the single optical element acts as a reflecting mirror, that is to say as a beam folding element. That is to say, if the single optical element is used in an imaging optics which has a primary mirror downstream of the single optical element in the principal direction of passage, a beam path which runs in the principal direction of passage and falls outside the central inner region onto the entrance side of the single optical element can pass through the latter unimpeded. If the beam path then subsequently strikes the primary mirror, it is retroreflected by this again onto the single optical element in a fashion opposing the principal direction of passage. If it penetrates the single optical element in the process and in so doing strikes the mirror-coated central inner region of the entrance side, the beam path is returned again in the principal direction of passage. Thus, the single optical element thereby serves as secondary mirror in such an imaging optics. Since this secondary mirror constitutes an integral component of the single optical element, there is no need for any additional mirror holder. Problems usually caused by such holders - with regard to generation of scattered light and point image spread, for example - are thereby reduced. That is to say, the image quality of an imaging optics is positively influenced by such a single optical element.
It is particularly expedient when the central inner region cooperates with a part of the entrance side and a part of the exit side as a Mangin mirror. This means in other words that, with its associated outer surfaces, that this to say the mirror-coated part of the entrance side and the part of the exit side lying opposite, this central inner region constitutes a lens mirror-coated at the rear. Consequently, the central inner region of the single optical element serves not only as a secondary mirror, but simultaneously fulfils the function of an image field flattening lens given appropriate configuration. It is sensible here for this rear lens to be designed geometrically such that it corrects an image field curvature of a specific primary mirror of an imaging optics in which the single optical element lies upstream of the same in the principal direction of passage. Furthermore, it can be provided in this case that the non-mirror-coated surface of the lens corrects the aberration of its reflecting surface, that is to say of the mirror-coated part of the entrance side. The use of such a single optical element in an imaging optics thereby corrects the aberrations thereof and thus raises the quality of the imaging optics.
It is particularly practical when an edge region which runs around the inner region of the single optical element is fashioned as a Schmidt correction plate. Owing to the fact that the edge region is fashioned as a Schmidt correction plate, all the radiation which is required to achieve effective imaging passes through the single optical element in the principal direction of passage. Only radiation which strikes the central inner region with the mirror coating is lost. However, it is expedient to design the central inner region to be substantially smaller in area than the encircling edge region. It is thereby possible to neglect a loss of information owing to losses of energy and intensity which is associated with the passage of radiation through the single optical element. With the inner region and encircling edge region fulfilling different optical functions, the form of the single optical element provides a multifunctional optical element which is geometrically compact and thus also light.
It is expedient for the exit side of the single optical element to be fashioned in such a way that it has an optically scattering action in its edge region, and an optically collecting action in its central inner region. If the single optical element is now subjected to a temperature change, automatic compensation of the associated change in refractive index of the single optical element takes place. The same holds for changes in refractive power which are caused by changes in the radius of the single optical element, or by instances of sagging of the same owing to external loads. Owing to the fact that the single optical element is produced from one piece, the problems with the refractive index which depend on external influences are already eased. For example, a temperature rise in the material of the single optical element could lead to an increase in the refractive index. In such a case, a beam path which passes through the single optical element in the principal direction of passage would now be scattered less strongly by the optically scattering action of the edge region of the exit side than before the temperature increase. The same beam path is then retroreflected by a primary mirror onto the optical element in a fashion opposing the principal direction of passage, and strikes the inner region of the exit side, which has a collecting effect. It now experiences less of a collecting effect than before the temperature increase owing to the raised index of refraction. That is to say, if the single optical element consists of one material, a virtually complete automatic compensation is possible. Thus, no matter what the ambient temperature is in such a case, the influence on the beam path is always the same, nevertheless. An undesired beam expansion or reduction is thereby avoided.
It is particularly advantageous when the single optical element consists of a material which is transparent to radiation in the infrared spectral region. The single optical element can thereby be used in imaging optics for thermography. Thermography by means of an imaging optics which is transparent in the infrared spectral region is used in the military sector for terrain enquiries and reconnaissance for example. Zinc sulphide, zinc selenide or germanium, for example, are conceivable as infrared optical materials.
It is very particularly expedient when the single optical element is produced at least partially from germanium. To be precise, with germanium the change in the imaging properties which is caused by material dispersion is so slight that the same single optical element can be used both in a spectral region from 3 to 5 μητι and in a spectral region from 8 to 12 μηη. Consequently, the two wavelength regions can be used simultaneously with the same single optical element when used with detectors which are tuned to the corresponding spectral region.
It is practical for the single optical element to be fabricated from a material which is suitable for machining by means of diamond turning. Aspheric forms of the single optical element can thereby be produced easily and inexpensively. Furthermore, regions of the single optical element such as, for example, its edge region and inner region, which are intended to have a different optical power and therefore require a different geometrical configuration, can be produced on the same machine and in the same setup. This ensures that there is no decentring or tilting of the regions relative to one another. It is thereby possible to achieve an optimum imaging behaviour. The edge and inner regions can even adjoin one another without a transition given an appropriate dimensioning of their centre thicknesses.
The second-named object with regard to instances of technical use is achieved according to the invention by using the single optical element in a Schmidt system.
If the single optical element is used in a Schmidt system, the single optical element is arranged upstream of a primary mirror with reference to its principal direction of passage. Located between the primary mirror and the single optical element is the image plane of the Schmidt system, in which a detector is arranged for detecting the radiation inpinging thereon. An object scene can thereby be imaged onto the detector via the Schmidt system thus constructed. When passing through the single optical element in the principal direction of passage, a beam path experiences the action of the single optical element as a Schmidt correction plate. The beam path thus conditioned then strikes the primary mirror and is retroflected by it onto the single optical element in a fashion opposing the principal direction of passage. On the basis of the configuration of the single optical element as a reflecting mirror, the beam path is then reflected again in the principal direction of passage by a mirror coating on the entrance side. At the same time, on the basis of the configuration of the single optical element as an image field flattening lens, the beam path is subjected to the image field flattening function thereof. The beam path thus corrected and conditioned then falls onto the detector.
It is advantageous, furthermore, when the single optical element is used in a Schmidt-Cassegrain system. In this arrangement, the single optical element is located with reference to its principal direction of passage upstream of a primary mirror which has an opening in its central region. A detector is located downstream of the primary mirror. A beam path which now passes through the single optical element in the principal direction of passage now experiences the latter functioning as a Schmidt correction plate because of its configuration. The beam path thus conditioned then - exactly as described before for the Schmidt system - strikes the primary mirror and is retroreflected by it onto the single optical element in a fashion opposing the principal direction of passage. In this case, the beam path is retroreflected again by the single optical element in the principal direction of passage and experiences the action of the single optical element as an image field flattening lens and as a reflecting mirror. The beam path thus modified is then guided out in the principal direction of passage through the central opening in the primary mirror, and strikes the detector arranged in the image plane of the Schmidt-Cassegrain system.
In a particularly advantageous refinement, the single optical element is used in a Schmidt-Cassegrain system which includes a number of baffle plates. These baffle plates can exert a positive influence on the imaging behaviour of the Schmidt-Cassegrain system, because the system is thereby protected against scattered and false light. These baffle plates expediently enclose the detector and the central inner region of the single optical element, which acts as an image field flattening lens.
It is very particularly expedient when the single optical element is used in one of the previously described Schmidt-Cassegrain systems which comprise a relay optics. Thus, if the previously described optics of the Schmidt-Cassegrain system is supplemented by a relay optics, the result in this case is an optics with intermediate imaging. Such an optics has a freely accessible exit pupil. It is thereby possible when using a cooled detector to place the cold plate thereof at the position of the exit pupil. It is thereby possible to achieve a very high cold plate efficiency close to 1 , since the false light component is particularly effectively suppressed. Extraneous radiation components inside a housing of the detector which are caused by laser irradiation and insolation, for example, are largely avoided. Moreover, the intermediate image plane resulting from the relay optics permits a field stop to be mounted in the same. The field stop determines the size of the imagable field. The edge of the field is thereby sharply delimited and can thus be tuned to the proportions of the detector. Excellent scattered light properties can be achieved by combining such a field stop with a cold plate, which can be designed in the manner of a Lyot stop.
In practical terms, the Lyot stop is a circular stop. Owing to the circular structure of the Lyot stop, disturbing light irradiated from the centre of a field of view such as, for example, solar or laser radiation which would prevent the detection of objects located in the vicinity of the high intensity radiation source can be blocked out.
Exemplary embodiments of the invention are explained in more detail with the aid of a drawing, in which: Figure 1 shows a Schmidt system having a single optical element, and Figure 2 shows a Schmidt-Cassegrain system having a single optical element.
Functionally identical parts are denoted here by the same reference numerals.
Table 1 lists the design values of the Schmidt system according to Figure 1.
Table 2 lists the design values of the Schmidt-Cassegrain system according to Figure 2.
Figure 1 shows a Schmidt system 10 having a single optical element 12. The principal direction of passage through the single optical element 12 is marked by an arrow 14. The optical element 12 has an entrance side 6 and an exit side 18. The single optical element 12 is cylindrical. Its outer edge region 20 here encircles its central inner region 22. The entrance side 16 of the optical element 12 is provided with a mirror-coating layer 24 in the region of the central inner region 22. The central inner region 22 is fashioned as a Mangin mirror. Its outer surfaces are formed by the mirror coating layer 24 and the surface 26, which lies opposite on the exit side 18 and the mirror coating layer 24. The central inner region 22 is therefore designed as a lens mirror-coated at the rear. The entrance side 16 of the single optical element 12 is flat, whereas the exit side 18, by contrast is aspherically shaped. Whereas the entrance side 16 is flat both in its edge region 20 and in its central inner region 22, in the edge region the exit side 18 is designed aspherically otherwise than the central inner region 22. The edge region 20 is fashioned as a Schmidt correction plate on the basis of its shaping. The central inner region 22, which constitutes a lens mirror-coated at the rear, is fashioned by virtue of its shaping and the mirror coating 24 as an image field flattening lens and as a reflecting mirror.
In the Schmidt system 10 shown, a beam path passes in the principal direction of passage 14 through the single optical element 12 in its edge region 20. In the process, the beam path experiences the correcting action of a Schmidt correction plate. It is to be seen from Figure 1 that the edge region 20 has a slightly scattering effect on a beam path passing through. The beam path now thus modified thereafter strikes an aspherically shaped primary mirror 28. The latter retroreflects the beam path onto the single optical element 12 in a fashion opposing the principal direction of passage 14. In this case, the beam path penetrates the single optical element 12 in the direction from its exit side 18 to the entrance side 16. More precisely, the beam path in this case penetrates the single optical element 12 in its central inner region 22 and strikes the mirror coating layer 24 there. This mirror coating layer 24 reflects the beam again in the principal direction of passage 14, and the beam in this case traverses the single optical element 12 once more. The mirror coating layer 24 here constitutes a reflecting secondary mirror. The beam path experiences an image field flattening action here, since the central inner region 22 is fashioned as an image field flattening lens. The beam path subsequently strikes a detector 30. It may be gathered from Figure 1 that the central inner region 22 has a collecting effect on the beam path.
The exact design data of the Schmidt system 10 according to Figure 1 may be gathered from Table 1 . Table 1 sets forth both the aspheric data of the single optical element 12 and the primary mirror 28, and the materials used. The shape of the aspheric surfaces is defined in accordance with the following formula: z = c j ; + adr4 + aer4 + afr8 + agr10 l + Vl - cv^cc + IJ r2 In the formula above, r denotes the radius, cv the curvature, cc the conic constant, and ad, ae, af, ag the aspheric coefficients.
Both in the spectral region from 3 to 5 μπ\ and in the spectral region from 8 to 12 yt/m, the Schmidt optics 10 in this case achieve a diffraction-limited imaging quality given an F number (stop number) of 1 .5, an angular field of view of 3° and a focal length of 100 mm. The imaging-relevant variables such as, for example, focal length, stop number or space in between a single optical element 12 and primary mirror 28, can be adapted to the respective requirements depending on the corresponding field of use.
Table 1 Design values of the Schmidt system 10 Figure 2 shows a Schmidt-Cassegrain system 32 having a single optical element 12. The Schmidt-Cassegrain system 32 illustrated exhibits invariably good, detraction-limited imaging properties in a spectral region from 3 to 5 /m and over a temperature range from -25°C to +25°C. The exact design values of the Schmidt-Cassegrain system 32, and the materials used can be gathered from the associated Table 2. The shape of the aspheric surfaces is described according to the formula already introduced previously.
The mode of operation of the single optical element 12 in this case is the same as in the Schmidt optics 10, which was described previously in conjunction with Figure 1. By contrast with the Schmidt optics 10, however, the Schmidt-Cassegrain system 32 has a differently fashioned primary mirror 34. The aspherically shaped primary mirror 34 has a central opening 35 downstream of which with reference to the principal direction of passage 14 a detector 30 is located. Not until after a beam path has passed through the single optical element 12 and been retroreflected onto the single optical element 12 by the primary mirror 34, and has penetrated the single optical element again in the process and been retroreflected by the latter in the principal direction of passage 14 via the mirror coating layer 24 does it then pass through a relay optics 36 and thereafter reach the detector 30. The relay optics 36 images onto the detector an image produced in the intermediate image plane. The relay optics 36 used here comprises four lenses 38, 40, 42 and 44.
Table 2 Design data of the Schmidt-Cassegrain system 32 Radius (mm) Thickness Aperture Material Comments (mm) or radius (mm) spacing (mm) Object plane Air Aperture stop 68.965474 72.408869 68.620646 Aperture stop, not shown -65.486276 40.333100 Air Spacing from the single optical element 12 .171686 38.615258 Germanium Edge region 20 (Schmidt correction plate) 40.177364 38.615258 Air Spacing from the primary mirror 34 or spacing from the central opening 35 -110.762344 -40.177364 41.359753 Retroreflection -5.171738 18.00000 Zinc sulphide Inner region 22 (mirror and image field flattening lens) .171738 18.00000 Renewed reflection 11.037425 18.00000 Air Spacing from the lens 38 .859034 2.133360 Air Spacing from the lens 38 -16.109223 3.214711 6.170810 Germanium Lens 38 -36.338459 0.100000 7.646857 Air Spacing from the lens 40 -33.897571 2.758492 7.767933 Silicon Lens 40 -14.096099 3.564918 9.190755 Air Spacing from the lens 42 61.197257 2.758492 9.041283 Silicon Lens 42 -413.990932 6.082749 8.448544 Air Spacing from the lens 44 9.935008 2.290054 8.096642 Germanium Lens 44 9.445879 2.666137 6.545476 Air Spacing from detector 30 12.990473 4.984396 Air Spacing from detector 30 Image plane 3.321618 Detector 30 Aspheric data (conic and polynomial) CC AD AE AF AG 4 6.4403E-08 1.0250E-12 1.0766E-15 -1.6944E-19 0.392071 6 7.4839E-06 -3.2806E-08 7.2880E-11 -6.7013E-14 8 7.4839E-06 3.2806E-08 7.2880E-11 -6.7013E-14 List of reference numerals Schmidt system Single optical element Principal direction of passage Entrance side Exit side Edge region Central inner region Mirror coating layer Surface Primary mirror Detector Schmidt-Cassegrain system Primary mirror Central opening Relay optics Lens Lens Lens Lens
Claims (9)
1. A single optical element (12) with a main direction of transmission (14) from an entrance side (16) in direction of an exit side (18), comprising a Schmidt corrector plate, a field flattening lens and a reflecting mirror wherein the entrance side is plane and comprises a peripheral region which surrounds a central inner region, wherein the central inner region is provided with a reflective surface, and co operates with a portion on the entrance side and a portion on the exit side as a Mangin mirror and wherein said peripheral region is formed as a Schmidt corrector plate, the exit side being formed in such a way that it has an optically diverging effect in its peripheral region and an optically converging effect in its central inner region.
2. A single optical element (12) as claimed in claim 1 wherein its exit side (18) is aspherical in form.
3. A single optical element (12) as claimed in claim 1 or 2 wherein the element is cylindrical in form.
4. A single optical element (12) as claimed in any preceding claim wherein the element is made of a material which is transparent to radiation in the infra red spectral region.
5. Use of a single optical element (12) according to any preceding claim in a Schmidt system (10).
6. Use of a single optical element (12) according to Claim 5 in a Schmidt-Cassegrain system (32).
7. Use of the single optical element (12) according to Claim 6 in a Schmidt-Cassegrain system (32) involving a number of baffles.
8. Use of the single optical element (12) according to one of Claims 6 or 7 in a Schmidt-Cassegrain system (32), which includes an optical relay system (36). - 18 - 175236/2
9. A single optical element (12) as substantially described herein with reference to figures 1 and 2 of the drawings. For the Applicant Pearl CCoohh^en i ZeeccteteAk L.atzer Advocates, Notaries & Patent Attorneys P-8644-IL
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102005021506A DE102005021506B4 (en) | 2005-05-10 | 2005-05-10 | Single optical element and its use |
Publications (2)
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| IL175236A0 IL175236A0 (en) | 2006-10-05 |
| IL175236A true IL175236A (en) | 2011-03-31 |
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| IL175236A IL175236A (en) | 2005-05-10 | 2006-04-26 | Single optical element and its use |
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| DE (1) | DE102005021506B4 (en) |
| FR (1) | FR2885703B1 (en) |
| GB (1) | GB2426077B (en) |
| IL (1) | IL175236A (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104035188A (en) * | 2014-06-10 | 2014-09-10 | 西南技术物理研究所 | Low-cost refracting-reflecting athermalizing medium wave infrared lens |
| CN106444019A (en) * | 2016-12-06 | 2017-02-22 | 中国科学院长春光学精密机械与物理研究所 | Stabilized broadband optical system |
| CN106680975B (en) * | 2017-02-28 | 2022-08-09 | 福鼎市一雄光学仪器有限公司 | Maca micro-electric telephoto lens |
| JP6815375B2 (en) * | 2018-02-27 | 2021-01-20 | 富士フイルム株式会社 | Variable magnification optical system and imaging device |
| CN108957725A (en) * | 2018-07-25 | 2018-12-07 | 中国科学院国家天文台南京天文光学技术研究所 | Improved Schmidt telescopic optical system |
| CN109298517B (en) * | 2018-11-05 | 2020-10-30 | 中国航空工业集团公司洛阳电光设备研究所 | Multispectral coaxial catadioptric afocal optical system |
| CN113946041B (en) * | 2021-10-22 | 2022-09-20 | 中国科学院长春光学精密机械与物理研究所 | Catadioptric Cassegrain telescope system and polarization aberration correction method thereof |
| DE102021005406B4 (en) | 2021-10-30 | 2023-06-22 | Diehl Defence Gmbh & Co. Kg | Optical device for detecting an object scene and seeker |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3064526A (en) * | 1958-06-23 | 1962-11-20 | Wesley N Lindsay | Dual image reflecting telescope |
| FR2044517A5 (en) * | 1969-05-23 | 1971-02-19 | Compteurs Comp D | |
| JPS6018045B2 (en) * | 1977-04-22 | 1985-05-08 | オリンパス光学工業株式会社 | reflective objective lens |
| US4342503A (en) * | 1979-10-09 | 1982-08-03 | The Perkin-Elmer Corporation | Catadioptric telescopes |
| DE3119498A1 (en) * | 1981-05-15 | 1982-12-02 | Messerschmitt Boelkow Blohm | Lens |
| US4576447A (en) * | 1983-09-26 | 1986-03-18 | The Boeing Company | Compact, single piece laser beam analyzer |
| US4981343A (en) * | 1989-02-06 | 1991-01-01 | Whittaker Ordnance, Inc. | Focusing mirror lens |
| RU2012907C1 (en) * | 1991-06-03 | 1994-05-15 | Государственное предприятие "Производственное объединение "Красногорский завод им.С.А.Зверева" | Catadioptric lens |
| US5471346A (en) * | 1992-03-13 | 1995-11-28 | Lockheed Missiles & Space Co., Inc. | Casegrain telescope with spherical mirror surfaces |
| JP3382683B2 (en) * | 1993-10-22 | 2003-03-04 | オリンパス光学工業株式会社 | Concentric optical system |
| ES2102309B1 (en) * | 1994-06-30 | 1998-01-01 | Puerta Antonio Medina | ULTRACOMPACT COMPLEX OPTICAL. |
| FR2761215B3 (en) * | 1997-03-24 | 1999-05-21 | Matra Marconi Space France | TELECOMMUNICATION TERMINAL BY OPTICAL BEAMS |
| GB9721991D0 (en) * | 1997-10-18 | 1997-12-17 | Secr Defence | Optical systems |
| US20020171896A1 (en) * | 2001-05-21 | 2002-11-21 | Lightpointe Communications, Inc. | Free-space optical communication system employing wavelength conversion |
| US6867930B1 (en) * | 2003-04-18 | 2005-03-15 | Lockheed Martin Corporation | Infrared optics and manufacture thereof |
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2005
- 2005-05-10 DE DE102005021506A patent/DE102005021506B4/en not_active Expired - Fee Related
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2006
- 2006-04-26 IL IL175236A patent/IL175236A/en not_active IP Right Cessation
- 2006-05-02 GB GB0608584A patent/GB2426077B/en not_active Expired - Fee Related
- 2006-05-03 FR FR0603931A patent/FR2885703B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| GB0608584D0 (en) | 2006-06-07 |
| IL175236A0 (en) | 2006-10-05 |
| DE102005021506A1 (en) | 2006-11-23 |
| DE102005021506B4 (en) | 2012-02-16 |
| GB2426077A (en) | 2006-11-15 |
| GB2426077B (en) | 2010-04-14 |
| FR2885703B1 (en) | 2008-05-02 |
| FR2885703A1 (en) | 2006-11-17 |
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