CN111624752A - Compact type long-focus four-reflection telescopic optical system - Google Patents
Compact type long-focus four-reflection telescopic optical system Download PDFInfo
- Publication number
- CN111624752A CN111624752A CN202010528476.8A CN202010528476A CN111624752A CN 111624752 A CN111624752 A CN 111624752A CN 202010528476 A CN202010528476 A CN 202010528476A CN 111624752 A CN111624752 A CN 111624752A
- Authority
- CN
- China
- Prior art keywords
- mirror
- optical system
- primary
- compact
- tele
- 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.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B17/00—Systems with reflecting surfaces, with or without refracting elements
- G02B17/02—Catoptric systems, e.g. image erecting and reversing system
- G02B17/06—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror
- G02B17/0647—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror using more than three curved mirrors
- G02B17/0652—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror using more than three curved mirrors on-axis systems with at least one of the mirrors having a central aperture
Abstract
The invention discloses a compact long-focus four-reflection telescope optical system, which comprises four optical reflecting surfaces and two reflector elements, wherein according to the incidence sequence of light rays, the optical reflecting surfaces sequentially pass through a primary mirror, a secondary mirror, a tertiary mirror, a quaternary mirror and a focal plane, the primary mirror and the tertiary mirror form a primary image surface, the primary image surface is imaged to the focal plane through the tertiary mirror and the quaternary mirror, the secondary blocking-free design is realized, the four reflectors are in axial optical axis symmetry structures, aperture diaphragms are positioned at the primary mirror, and are combined and processed into a primary three-in-one reflector which can be processed into a secondary four-in-one reflector. The method is suitable for realizing the ultra-compact and ultra-light space remote sensing optical imaging system.
Description
Technical Field
The invention relates to the technical field of optical design and space optical imaging detection, in particular to a compact type long-focus four-reflection telescopic optical system which can be used for compact and light space remote sensing cameras.
Background
The telescopic optical system is a widely used optical system and has numerous applications in the fields of astronomy, national defense and aerospace. The telescope optical system can be divided into three types, namely a reflection type telescope objective lens, a refraction type telescope objective lens and a catadioptric hybrid telescope objective lens according to optical elements used, wherein the reflection type telescope objective lens has the technical characteristics of long focal length, no chromatic aberration and compact structure, and is widely used.
In recent years, space remote sensing satellites have a trend towards miniaturization development, wherein micro-nano satellites with the mass of about 50kg become an industry focus of attention due to the advantages of lower development and emission cost, short period, high flexibility and small volume; in order to manufacture a remote sensing optical load which is adaptive to a micro-nano satellite platform and can obtain a high-quality image, a telescopic optical system with high spatial resolution is required to be designed under the limitation of volume and quality.
An optical system of the space camera usually adopts a coaxial three-reflection structure, and in order to avoid secondary blocking and shorten the size, a plurality of plane mirror folding light paths or inclined view fields are usually added for use, so that the optical system is complex and the size is shortened limitedly; the coaxial four-reflector optical system object image is positioned on the opposite side of the system, an image surface can be directly led out, and more optimization freedom degrees are provided; but the requirements for design and adjustment are higher while the performance of the telescopic optical system is improved; the total length of the system is shortened, so that the relative aperture of the aspheric surface reflector is increased, the surface shape processing difficulty is obviously increased, and the processing period and cost of the optical element are increased; the four-reflector optical structure makes the assembling tolerance of each optical element stricter, increases the assembling difficulty and complexity, and particularly has more outstanding problems in a large-aperture telephoto objective lens.
For comparison, reference is made to the patents: the optical system index of the telescope objective with a four-mirror reflection structure provided in CN201210334328.8[ P ] 2013-01-09 is that the diameter of an entrance pupil is 625mm, the focal length is 10000mm, the F number is 16, the whole line view field is 1.5 degrees, the whole length of the system is 1158mm, the optical system structure of coaxial three-mirror reflection TMA and a low-focal-power four-mirror is adopted, an aperture diaphragm is positioned on a main mirror, the oblique view field of the system is used, a plane mirror is added to realize the folding of an optical path, the length-diameter ratio of the system is close to 2, and all 5 optical elements need to be independently processed, installed and calibrated. The length-diameter ratio and the installation and adjustment difficulty are both larger than those of the design example in the invention.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, provides a compact type long-focus four-reflection telescope optical system, is suitable for a micro-nano satellite-borne ground remote sensing camera, can realize high resolution, compactness and light weight, has few optical elements, and greatly reduces the installation and adjustment difficulty of the optical system.
The above purpose is mainly realized by the following technical scheme:
the utility model provides a compact long focus four reflection telescope optical system, includes effective optical surface primary mirror, secondary mirror, three mirrors, four mirrors and focal plane, the primary mirror the secondary mirror three mirrors with four mirrors are axial light axisymmetric structure, the primary mirror be equipped with intermediate image behind the secondary mirror, three mirrors establish behind the four mirrors into formation of image focal plane, the primary mirror with three mirrors are the ellipsoid surface, the secondary mirror four mirrors are the hyperboloid, the secondary mirror three mirrors four mirrors contain aspheric surface high order item, the primary mirror three mirrors close to process into main three integrative speculum, the secondary mirror four mirrors close to process into secondary four integrative speculum, just the secondary mirror with the surface shape parameter of four mirrors is unanimous, shares same surface.
Preferably, the axial distance between the main mirror and the vertex of the three mirrors is 8-10 mm.
Preferably, the secondary mirror is completely consistent with the shape parameters of the four mirror surfaces and the positions of the surface vertexes coincide.
Preferably, the total length of the compact tele-tetra-telescope optical system is 1/8-1/7 of the effective focal length.
Preferably, the blocking coefficient of the compact type long-focus four-reflection telescopic optical system is 0.4-0.5.
Preferably, an outer light shield is arranged on the outer edge of the primary mirror, the secondary mirror and an inner light shield arranged between the primary mirror and the secondary mirror are used for inhibiting primary stray light, and the length of the outer light shield does not exceed the axial position of the secondary mirror.
Preferably, the method is more suitable for machining the optical reflecting surface by adopting a single-point diamond turning process, and high-precision integrated machining of the primary three-in-one reflector and the secondary four-in-one reflector is realized.
Preferably, vertex curvature radii of the primary mirror, the secondary mirror, the three-mirror and the four-mirror satisfy a flat image field condition of 1/R1-1/R2+1/R3-1/R4 ═ 0 and a coplanar condition of R2 ═ R4, wherein R1, R2, R3 and R4 are vertex curvature radii respectively and correspond to the vertex curvature radii of the primary mirror, the secondary mirror, the three-mirror and the four-mirror, the value range of R1 is-320 to-250 mm, the value ranges of R2 and R4 are-200 to-160 mm, and the value range of R3 is-137 to-100 mm.
Advantageous effects
Compared with the prior art, the invention has the following beneficial effects:
on the basis of a conventional long-focus coaxial four-reflection optical system, the total length of the coaxial four-reflection system is reduced by coplanar secondary mirrors and four mirrors and coaxial nested design of a primary mirror and three mirrors, the total length of the optical system is 1/8-1/7 of an effective focal length, the imaging quality is close to a diffraction limit, the structure is compact, the total volume is only about 1/3 of that of a similar index system, and the optical system has great advantages when being used as a satellite-borne remote sensing camera optical system.
The secondary mirror and the four mirrors in the optical system are coplanar, and the primary mirror and the three mirrors are coaxially nested, so that the number of optical elements of the four-mirror optical system is reduced to two, the assembly alignment requirement is moved forward to the processing stage of the optical elements, the precision is improved to the level of ultra-precision processing errors, the processing number of the optical elements can be reduced, the system quality is reduced, the design of a reflector supporting structure is simplified, the processing cost is saved, the assembly steps are reduced, the development period is shortened, and the rapid and batch manufacturing of the satellite-borne remote sensing camera is facilitated.
Drawings
FIG. 1 is a diagram of the optical path structure of the compact tele-FOUR optical system of the present invention;
FIG. 2 is a graph of the modulation transfer function of an optical system in an embodiment of the present invention;
FIG. 3 is a dot diagram of an optical system in an embodiment of the present invention;
FIG. 4 is a diagram illustrating the grid distortion of an optical system according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a light shield associated with an optical system in an embodiment of the present invention.
Reference numerals
1-primary mirror, 2-secondary mirror, 3-triple mirror, 4-quadruple mirror, 5-focal plane, 6-primary triple-integral mirror and 7-secondary quadruple-integral mirror.
Detailed Description
The following are specific examples of the present invention and further describe the technical solutions of the present invention, but the present invention is not limited to these examples.
Example 1
The compact type long-focus four-reflection telescopic optical system is of a concave-convex-concave-convex structure, and the primary mirror 1, the secondary mirror 2, the third mirror 3 and the fourth mirror 4 are all aspheric surfaces; the entrance pupil of the optical system is positioned at the main mirror, the diameter of the entrance pupil is 200mm, the optical length is 211mm, the focal length is 1400mm, the F number is 7, the working waveband of the full field angle of 1.33 degrees is 400-900 nm, and the obscuration ratio is 0.48;
the optical system structure of this embodiment is shown in fig. 1, and the optical path is described as follows: light in the imaging light path is reflected to the secondary mirror 2 through the primary mirror 1, reflected by the secondary mirror 2 to be imaged to a primary image surface, the imaging light is reflected to the four mirrors 4 through the three mirrors 3, and the light reflected by the four mirrors 4 passes through a central hole of the three mirrors 3 and then is imaged to the focal plane 5. The axial distance between the primary mirror 1 and the secondary mirror 2 is 118mm, and the axial distance between the secondary mirror 2 and the third mirror 3 is 123 mm.
As shown in the light envelope of the optical system of the embodiment shown in FIG. 1, the primary mirror 1 and the three mirrors 3 are concave ellipsoidal surfaces. In the optical design, the three mirrors 3 are coaxially nested in the central hole of the main mirror 1, the outer edges of the three mirrors 3 and the inner edge of the main mirror 1 are in a same circle, and the main mirror 1 and the three mirrors 3 are combined into a main three-in-one reflector 6 for processing.
As shown in the light envelope of the optical system of the embodiment shown in FIG. 1, the secondary mirror 2 and the four-mirror 4 are convex hyperboloids, and the surface parameters are completely consistent and the surfaces are coincident. The light transmission apertures of the secondary mirror 2 and the four-mirror 4 are annular, and have partial apertures overlapped, and the secondary mirror 2 and the four-mirror 4 are combined into a secondary four-integrated reflector 7 according to the size of the overlapped apertures for processing.
The secondary coefficient of the primary mirror is-1 to-0.6, the secondary coefficient of the secondary mirror and the secondary coefficient of the fourth mirror are-2 to-3, and the secondary coefficient of the third mirror is-1 to-0.7. The curvature radiuses of the vertexes of the primary mirror, the secondary mirror, the tertiary mirror and the quaternary mirror meet the condition of a flat image field, namely 1/R1-1/R2+1/R3-1/R4 ═ 0, and the coplanar condition R2 ═ R4, wherein R1, R2, R3 and R4 respectively correspond to the curvature radiuses of the vertexes of the primary mirror, the secondary mirror, the tertiary mirror and the quaternary mirror, the value range of R1 is-350 to-250 mm, the value ranges of R2 and R4 are-200 to-150 mm, and the value range of R3 is-150 to-100 mm.
The main three-in-one reflector 6 and the secondary four-in-one reflector 7 are made of 6061-T6 aluminum alloy, and the reflectivity is improved by a silver coating through the ultra-precision processing of the surface shape of a mirror surface by a single-point diamond.
Fig. 2 is a plot of the modulation transfer function of an example optical system with field of view on the ordinate and resolution (in lp/mm) on the abscissa, taking a reference wavelength of 632.8nm, taking 5 reference fields of 0.665 °, 0.498 °, 0.332 °, 0.166 °, 0 °, and one can see an MTF value of 0.4 for each field at 50lp/mm and close to the diffraction limit.
Fig. 3 is a point array diagram of the optical system of the embodiment, and similarly, 5 reference fields of view of 0.665 °, 0.498 °, 0.332 °, 0.166 °, and 0 ° are taken, and it can be seen that the energy of the image spot of each field of view point array is concentrated in the airy disk range, and the imaging quality is close to the diffraction limit.
Fig. 4 is a grid distortion diagram of the optical system of the embodiment, and it can be seen that the maximum distortion of the system is less than 0.1%, which is very beneficial to the application of space to ground remote sensing.
FIG. 5 shows a model of a parasitic light reduction mask design and a sub-quad mirror support structure associated with an optical system of an embodiment.
The specific system design parameters of this embodiment are as follows:
imaging optical system parameters:
finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the content of the present invention within the scope of the protection of the present invention.
Claims (8)
1. The compact type long-focus four-reflection telescope optical system comprises a primary optical surface mirror (1), a secondary mirror (2), a tertiary mirror (3), a quaternary mirror (4) and a focal plane (5), wherein the primary mirror (1), the secondary mirror (2), the tertiary mirror (3) and the quaternary mirror (4) are in axial optical axis symmetry structure, an intermediate image is arranged behind the primary mirror (1) and the secondary mirror (2), the imaging focal plane is arranged behind the tertiary mirror (3) and the quaternary mirror (4), the primary mirror (1) and the tertiary mirror (3) are ellipsoidal, the secondary mirror (2) and the quaternary mirror (4) are hyperboloids, the secondary mirror (2), the tertiary mirror (3) and the quaternary mirror (4) contain high-order aspheric surface items, the primary mirror (1) and the tertiary mirror (3) are combined and processed into a primary three-in-one reflector (6), the secondary mirror (2) and the quaternary mirror (4) are combined and processed into a secondary four-in-one reflector (7), and the surface shape parameters of the secondary mirror (2) and the surface shape parameters of the four mirrors (4) are consistent and share the same surface.
2. The compact tele quadric telescope optical system of claim 1, wherein: the axial distance between the main mirror (1) and the vertex of the three mirrors (3) is 8-10 mm.
3. The compact tele quadric telescope optical system of claim 1, wherein: the secondary mirror (2) and the four-mirror (4) have completely consistent surface shape parameters and are overlapped at the vertex position of the surface.
4. The compact tele quadric telescope optical system of claim 1, wherein: the total length of the compact type tele-tetra-telescope optical system is 1/8-1/7 of an effective focal length.
5. The compact tele quadric telescope optical system of claim 1, wherein: the blocking coefficient of the compact type long-focus four-reflection telescopic optical system is 0.4-0.5.
6. The compact tele quadric telescope optical system of claim 1, wherein: the outer edge of the primary mirror (1) is provided with an outer light shield, the secondary mirror (2) and an inner light shield arranged between the three mirrors (3) are used for inhibiting primary stray light, and the length of the outer light shield does not exceed the axial position of the secondary mirror (2).
7. The compact tele quadric telescope optical system of claim 1, wherein: the method is more suitable for machining the optical reflecting surface by adopting a single-point diamond turning process, and realizes high-precision integrated machining of the primary three-in-one reflector (6) and the secondary four-in-one reflector (7).
8. The compact tele quadric telescope optical system of claim 1, wherein: the vertex curvature radiuses of the four reflectors of the primary mirror (1), the secondary mirror (2), the three mirror (3) and the four mirror (4) meet a flat image field condition 1/R1-1/R2+1/R3-1/R4=0 and a coplanar condition R2= R4, wherein R1, R2, R3 and R4 are respectively the vertex curvature radiuses and correspond to the vertex curvature radiuses of the primary mirror (1), the secondary mirror (2), the three mirror (3) and the four mirror (4), the R1 ranges from-320 to-250 mm, the R2 and the R4 range from-200 to-160 mm, and the R3 ranges from-137 to-100 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010528476.8A CN111624752A (en) | 2020-06-11 | 2020-06-11 | Compact type long-focus four-reflection telescopic optical system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010528476.8A CN111624752A (en) | 2020-06-11 | 2020-06-11 | Compact type long-focus four-reflection telescopic optical system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111624752A true CN111624752A (en) | 2020-09-04 |
Family
ID=72272269
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010528476.8A Pending CN111624752A (en) | 2020-06-11 | 2020-06-11 | Compact type long-focus four-reflection telescopic optical system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111624752A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113031238A (en) * | 2021-04-14 | 2021-06-25 | 中国科学院长春光学精密机械与物理研究所 | Multi-mirror integrated large-view-field long-focus off-axis four-mirror optical system |
| CN113406781A (en) * | 2021-06-17 | 2021-09-17 | 苏州大学 | Coaxial four-reflection long-focus optical system, telescope objective optical machine and optical device |
| CN114637103A (en) * | 2022-02-25 | 2022-06-17 | 中国科学院西安光学精密机械研究所 | Long-focus optical lens and imaging device |
| CN114994913A (en) * | 2022-06-20 | 2022-09-02 | 中国科学院长春光学精密机械与物理研究所 | Low-sensitivity three-mirror telescope design method based on multi-initial-point quasi-Newton optimization |
-
2020
- 2020-06-11 CN CN202010528476.8A patent/CN111624752A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113031238A (en) * | 2021-04-14 | 2021-06-25 | 中国科学院长春光学精密机械与物理研究所 | Multi-mirror integrated large-view-field long-focus off-axis four-mirror optical system |
| CN113406781A (en) * | 2021-06-17 | 2021-09-17 | 苏州大学 | Coaxial four-reflection long-focus optical system, telescope objective optical machine and optical device |
| CN113406781B (en) * | 2021-06-17 | 2022-03-29 | 苏州大学 | Coaxial four-reflection long-focus optical system, telescope objective optical machine and optical device |
| CN114637103A (en) * | 2022-02-25 | 2022-06-17 | 中国科学院西安光学精密机械研究所 | Long-focus optical lens and imaging device |
| CN114637103B (en) * | 2022-02-25 | 2023-08-18 | 中国科学院西安光学精密机械研究所 | Long-focal-length optical lens and imaging device |
| CN114994913A (en) * | 2022-06-20 | 2022-09-02 | 中国科学院长春光学精密机械与物理研究所 | Low-sensitivity three-mirror telescope design method based on multi-initial-point quasi-Newton optimization |
| CN114994913B (en) * | 2022-06-20 | 2023-08-15 | 中国科学院长春光学精密机械与物理研究所 | Low-sensitivity three-reflector design method based on multi-initial-point quasi-Newton optimization |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111624752A (en) | Compact type long-focus four-reflection telescopic optical system | |
| CN108519664B (en) | Main three-mirror integrated coaxial three-reflection infrared optical imaging device | |
| CN109407290B (en) | Folding type ultrathin optical imaging system | |
| CN110579859A (en) | compact type long-focal-length star sensor telecentric optical system | |
| CN111367066B (en) | Coaxial four-reflection optical system | |
| US20210373303A1 (en) | Freeform surface off-axis three-mirror optical system | |
| CN112034605A (en) | Catadioptric Golay3 sparse aperture optical system | |
| CN116577921A (en) | Large-caliber coaxial three-reflector optical system and ultra-light silicon carbide reflector assembly thereof | |
| CN109239898B (en) | Compact coaxial refraction and reflection type telescope objective lens | |
| CN109188665B (en) | Off-axis three-mirror imaging system based on flat-plate phase element | |
| US11635611B2 (en) | Freeform surface optical telescope imaging system | |
| WO2001077734A1 (en) | Compact imaging system including an aspheric quaternary element | |
| CN113900242A (en) | Multiband common-path optical system | |
| CN114047618A (en) | Off-axis afocal optical system of large-caliber spherical primary mirror | |
| CN112630948A (en) | Catadioptric optical lens based on two Manman golden mirrors | |
| CN111025615B (en) | Optical system | |
| CN212207826U (en) | Compact type long-focus four-reflection telescopic optical system | |
| CN214067483U (en) | Catadioptric optical lens based on two Manman golden mirrors | |
| CN111880298B (en) | Annular aperture ultrathin broadband imaging system with multilayer diffraction structure | |
| CN210465831U (en) | Compact type long-focal-length star sensor telecentric optical system | |
| CN113031238A (en) | Multi-mirror integrated large-view-field long-focus off-axis four-mirror optical system | |
| CN102073131B (en) | Large-aperture totally-reflective optical synthetic aperture imaging system | |
| CN213302653U (en) | Catadioptric Golay3 sparse aperture optical system | |
| CN112666694B (en) | Catadioptric optical system | |
| CN113671680B (en) | Off-axis two-reflection multi-light combination optical main system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |