CN106383401A - Ultra-wide field-of-view off-axis three-reflector optical imaging system - Google Patents
Ultra-wide field-of-view off-axis three-reflector optical imaging system Download PDFInfo
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- CN106383401A CN106383401A CN201610986183.8A CN201610986183A CN106383401A CN 106383401 A CN106383401 A CN 106383401A CN 201610986183 A CN201610986183 A CN 201610986183A CN 106383401 A CN106383401 A CN 106383401A
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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
- G02B17/02—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
- G02B17/0626—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror using three curved mirrors
- G02B17/0642—Catoptric systems, e.g. image erecting and reversing system using mirrors only, i.e. having only one curved mirror using three curved mirrors off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
Abstract
The invention discloses an ultra-wide field-of-view off-axis three-reflector optical imaging system which comprises a main reflector with positive focal power, a second reflector with negative focal power, and a third reflector with positive focal power. The reflecting surface of the main reflector is a spherical surface. The reflecting surfaces of the secondary mirror and the third reflector are flat spherical secondary curved surfaces. The curvature radii of top points of the three reflectors approximately satisfy a flat image field condition. The main reflector generates a real image of a far scene between the main reflector and the second reflector. The second reflector and the third reflector perform relay imaging of the real image on an image plane. An aperture diaphragm is placed on the front focal plane of the third reflector, thereby realizing an image-side telecentric optical path. The main reflector inclines along an X-axis relative to incident main light of a central field-of-view. The second reflector is coaxial with the third reflector. After the main light of the central field-of-view in a meridian plane is reflected by the main reflector, an included angle is formed between the reflected main light and the common symmetric axis of the second reflector and the third reflector. The ultra-wide field-of-view off-axis three-reflector optical imaging system has advantages of ultra-wide field-of-view, intermediate relative aperture, wide working wave band, no image-side telecentric barrier, small object-side distortion, high imaging quality, etc. The ultra-wide field-of-view off-axis three-reflector optical imaging system is suitable for earth imaging observation field of a spatial camera, an imaging spectrometer, etc.
Description
Technical field
The present invention relates to a kind of can be used for space camera, the telephotolens of imaging spectrometer pre-objective, particularly to one
Plant the extremely wide field of view being operable with ultraviolet to infrared band from axle telecentricity three reflecting mirror telephotolens, belong to optical image technology neck
Domain.
Background technology
In recent years, big visual field width covers has become optical remote sensing instrument important development trend.Visual field is earth observation instrument
Important indicator, it determines Global coverage and the revisiting period of observation instrument, and visual field is bigger, and revisiting period is less, and the time divides
Resolution is higher.
Off-axis reflection optical system has that structure is simple, no color differnece, non-stop layer block, the object lens of large relative aperture that is easy to do, heat resistanceheat resistant
Performance is good, suitable lightweight the advantages of, also can obtain high-quality wide visual field scenery picture, can be used as broadband wide visual field high light spectrum image-forming
The pre-objective of instrument, becomes research and the focus of application.
Male-female and concave-concave two mirror system are suitable for wide visual field application.In prior art, document " object lens of large relative aperture width
The analysis of flat field two reflecting mirror telephotolens and design are no blocked in visual field "（Straight flat, Zhao Zhi really grade .. Acta Optica, 2015,35
(3):0322002）Report a kind of male-female two mirror-optical system, it can achieve wide visual field, object lens of large relative aperture and flattened field
Design, but the main deficiency existing is that this system only achieves 40 ° of linear fields, cannot arrange real aperture diaphragm during image space telecentricity,
During for wide visual field occasion, the veiling glare that disappears design is complicated, and the volume of shade and light-baffling device is increased with visual field with complexity
Greatly and quickly increase.Prior art（Referring to document： Nijkerk D, van Venrooy B, et al.. The TROPOMI
telescope, design, fabrication and test of a freeform optical system.
International Conference on Space Optics, 2012.）Report a kind of TROPOMI front-end system, by
The recessed free-form surface mirror of two panels forms, and there is middle real image it is convenient to shading fills in here setting field stop and design
Put, shade that need not be huge just can effectively suppress veiling glare.Its cross rail visual field reaches 108 °, but its relative aperture is less, limit
Make instrument signal to noise ratio to be lifted further.
Compared to two general mirror-optical systems, three-reflector optical system has more optimization degree of freedom, is increasing
Can obtain while big visual field and relatively seem matter.In United States Patent (USP) US 4240707, William B. Wetherell gives
The computer-aided alignment of one class Cook three-chip type, the principal reflection mirror of this system is the concave reflection of positive light coke
Mirror, secondary mirror is the convex reflecting mirror of negative power, and three mirrors are the concave mirror of positive light coke, and aperture diaphragm is placed on secondary mirror,
System can achieve 10 ° × 10 ° rectangular fields, or 35 ° of linear fields.However, this system relatively seems matter simultaneously it is difficult to real obtaining
Existing more than 100 ° of the wide line visual field.
Content of the invention
The present invention in view of the shortcomings of the prior art, is ensureing that one focuses overhang（Image planes are to the distance of secondary mirror）、
Telecentricity and explicit under the premise of, provide a kind of X-direction linear field angle to reach 108 ° it is adaptable to the nothing of ultraviolet to infrared band is blocked
Three mirror opticss imaging systems.This system not only achieves extremely wide field of view, medium relative aperture and flattened field design, and has
There are real aperture diaphragm and middle real image, be conducive to the veiling glare design that disappears.
To achieve the above object of the invention, the present invention adopts the following technical scheme that：There is provided a kind of extremely wide field of view from axle three reflection
Mirror optical imaging system, this optical system includes primary mirror, secondary mirror and three pieces of reflecting mirrors of three mirrors, aperture diaphragm and focal plane；Primary mirror
Tilt along X-axis with respect to central vision incidence chief ray, secondary mirror is coaxial with three mirrors, and aperture diaphragm is placed at the front focal plane of three mirrors,
Realize telecentric beam path in image space；From ground scenery incident ray through primary mirror reflection after, formed once between primary mirror and secondary mirror
Real image, secondary mirror and three mirrors, to the real image relay imaging obtaining, form scenery picture in focal plane；Primary mirror, secondary mirror and three mirrors
Three pieces of power of mirror distribution are followed successively by Negative-Positive-Negative, and their vertex curvature radius approximately meet flattened field condition, whereinR 1、R 2WithR 3It is respectively the vertex curvature radius of primary mirror, secondary mirror and three mirrors；Primary mirror type is sphere,
Secondary mirror and three mirror type are oblate spheroid type quadratic surface.
The extremely wide field of view off-axis incidence optical imaging system that the present invention provides, its relative aperture is 1/4～1/6.
In this optical system, the rotationally symmetrical overlapping of axles of secondary mirror and three mirrors；At the real image that also can be formed between primary mirror and secondary mirror,
Place field stop and interior shade.
The principle of the present invention is：On the basis of male-female two-mirror reflection penetrates mirror system, add one before convex reflecting mirror
Block concave mirror, for expanding visual field, forms new off-axis incidence structure so as to have convex-concave structure object lens of large relative aperture concurrently
With double-concave structure, there is middle real image, make system X-direction linear field angle reach 108 °.
Compared with prior art, the present invention has following features：
1st, on the basis of male-female two-mirror reflection penetrates mirror system, the system angle of visual field, X-direction are expanded using one piece of concave mirror
Linear field angle is up to 108 °.
2nd, system relative aperture is 1/4～1/6, is conducive to instrument to realize high s/n ratio.
3rd, the rotationally symmetrical overlapping of axles of secondary mirror and three mirrors, in axis, brings great convenience to system dress school.
4th, system aperture diaphragm is located at the front focal plane of three mirrors, realizes telecentric beam path in image space.
5th, system is imaging system twice, can place field stop and interior shade at a real image, need not be huge
Shade just can effectively suppress veiling glare.
6th, system adopts from axle total-reflection type structure, no blocks and no color differnece impact, is operable with ultraviolet to infrared band.
Brief description
Fig. 1 is optical imaging system light path schematic side view described in the embodiment of the present invention；
Fig. 2 is optical imaging system light path schematic top plan view described in the embodiment of the present invention；
Fig. 3 is the modulation transfer function (MTF) curve of optical imaging system described in the embodiment of the present invention；
Fig. 4 is the change curve with the angle of visual field for the image height of optical imaging system described in the embodiment of the present invention；
Fig. 5 is the Y-direction object space Distortion Law curve of optical imaging system described in the embodiment of the present invention；
In figure, 1, primary mirror；2nd, secondary mirror；3rd, three mirror；4th, system aperture diaphragm；5th, image planes；6th, the common symmetry axis of secondary mirror and three mirrors
Line.
Specific embodiment
With reference to the accompanying drawings and examples embodiment of the present invention is further specifically described.
Embodiment 1
The technical scheme that the present embodiment provides is applied to the preposition telescopic system of extremely wide field of view Hyperspectral imager.Referring to accompanying drawing
1 and 2, they are the present embodiment optical system imaging light path side-looking and schematic top plan view respectively.Wherein, 1 is primary mirror, and 2 is secondary mirror,
3 is three mirrors, and 4 is system aperture diaphragm, and 5 is image planes, and 6 is the common axis of symmetry of secondary mirror and three mirrors.In the present embodiment, choose
System image space focal lengthf=17mm, relative aperture D/F=1/4,108 ° × 0.05 ° of the angle of visual field, 0.27 μm～2.4 μm of wavelength.
From Fig. 1 and 2, the off-axis incidence telephotolens that the present embodiment provides includes primary mirror 1, secondary mirror 2 and three mirrors
3；Secondary mirror 2 is placed on the reflected light path of primary mirror 1, and three mirrors 3 are placed on the reflected light path of secondary mirror 2；For avoiding blocking and realizing image space
Telecentric beam path, primary mirror 1 is α with respect to central vision incidence chief ray along X-axis inclination angle, and secondary mirror 2 is coaxial with three mirrors 3, meridian plane
After primary mirror 1 reflection, the angle with secondary mirror 1, the common axis of symmetry 6 of three mirrors 3 is η to interior central vision chief ray, aperture diaphragm 4
It is placed at the front focal plane of three mirrors 3；For realizing required visual field width, primary mirror 1 adopts spherical reflector, secondary mirror 2 and three mirrors 3 to adopt
Disclosure satisfy that the aspherical mirror of low order that image quality requires, i.e. oblate spheroid type quadratic surface mirror, their vertex curvature radius are near
Seemingly meet flattened field condition, whereinR 1、R 2WithR 3It is respectively the vertex curvature half of primary mirror 1, secondary mirror 2 and three mirrors 3
Footpath, system X-direction linear field angle is 108 °.
Aperture diaphragm 4 is placed on the front focal plane of three mirrors 3, realizes telecentric beam path in image space, in the present embodiment, primary mirror 1 phase
Central vision incidence chief ray is 7 ° along X-axis inclined angle alpha, secondary mirror 2 is coaxial with three mirrors 3, central vision key light in meridian plane
Line, after primary mirror 1 reflection, is 32.8 ° with the angle η of secondary mirror 2 and the common axis of symmetry 6 of three mirrors 3.
By optical design software optimization design, the system concrete structure parameter obtaining is listed in table 1.
Table 1 system structure parameter
| Surface | Radius | Thickness | Glass | Conic | Tilt about X |
| Object | Infinity | Infinity | — | — | — |
| 1 | -180.000 | -315.898 | Mirror | — | 7° |
| 2 | -107.087 | 41.673 | Mirror | 3.654 | — |
| Stop | Infinity | 83.751 | — | — | — |
| 4 | -167.502 | -165.407 | Mirror | 0.063 | — |
| Image | Infinity | — | — | — | — |
Choose image height respectively (0,0), (4,0), (8,0), (12,0) and (16,0) five visual fields in image planes and carry out image quality
Evaluate, image height unit is mm.
Referring to accompanying drawing 3, it is modulation transfer function (MTF) at image plane for the present embodiment optical system（MTF）Curve chart, horizontal
Coordinate is spatial frequency, and, for system modulation transfer function values it is seen that image quality is close to diffraction limit, each visual field is in Jiao for vertical coordinate
At plane equivalent pixel size corresponding nyquist frequency 19.2lp/mm, mtf value is above 0.75.
Referring to accompanying drawing 4, it is the change curve with the angle of visual field for the image height of optical system, and abscissa is field angle of object, indulges
Coordinate is system image height it is known that image height and the angle of visual field approximately meetf -The Distortion Law relation of θ, is conducive in actual applications
Distortion is demarcated.
Referring to accompanying drawing 5, it is the Y-direction object space Distortion Law curve of optical system, and abscissa is X-direction true field
Angle, vertical coordinate is Y-direction field angle of object, and five points of curve side are respectively the corresponding thing of above-mentioned five image height points in image planes
The square angle of visual field is it is known that at peripheral field (54 °) place, Y-direction visual field offset amount is about 1.8 °, and shift ratio is about 1/30, and object space is abnormal
Become and control in the range of very little.
Claims (4)
1. a kind of extremely wide field of view off-axis incidence optical imaging system it is characterised in that：Optical system includes primary mirror（1）, secondary
Mirror（2）With three mirrors（3）Three pieces of reflecting mirrors, aperture diaphragm（4）And focal plane（5）；Primary mirror（1）With respect to central vision incidence key light
Line tilts along X-axis, secondary mirror（2）With three mirrors（3）Coaxially, aperture diaphragm（4）It is placed in three mirrors（3）Front focal plane at, realize image space remote
Heart light path；From ground scenery incident ray through primary mirror（1）After reflection, in primary mirror（1）And secondary mirror（2）Between formed once real
Picture, secondary mirror（2）With three mirrors（3）To the real image relay imaging obtaining, in focal plane（5）Place forms scenery picture；Primary mirror（1）、
Secondary mirror（2）With three mirrors（3）Three pieces of power of mirror distribution are followed successively by Negative-Positive-Negative, and their vertex curvature radius are approximately full
Sufficient flattened field condition, whereinR 1、R 2WithR 3It is respectively primary mirror（1）, secondary mirror（2）With three mirrors（3）Vertex curvature
Radius；Primary mirror（1）Face type is sphere, secondary mirror（2）With three mirrors（3）Face type is oblate spheroid type quadratic surface.
2. a kind of extremely wide field of view off-axis incidence optical imaging system according to claim 1 it is characterised in that：System
Relative aperture is 1/4～1/6.
3. a kind of extremely wide field of view off-axis incidence optical imaging system according to claim 1 it is characterised in that：Secondary mirror
（2）With three mirrors（3）Rotationally symmetrical overlapping of axles.
4. a kind of extremely wide field of view off-axis incidence optical imaging system according to claim 1 it is characterised in that：Leading
Mirror（1）And secondary mirror（2）Between place field stop and interior shade at a real image being formed.
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| CN201610986183.8A CN106383401B (en) | 2016-11-09 | 2016-11-09 | A kind of extremely wide field of view off-axis incidence optical imaging system |
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| CN201610986183.8A CN106383401B (en) | 2016-11-09 | 2016-11-09 | A kind of extremely wide field of view off-axis incidence optical imaging system |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107966804A (en) * | 2017-12-30 | 2018-04-27 | 苏州大学 | Four speculum telephotolens of compact long-focus |
| CN108426846A (en) * | 2018-06-14 | 2018-08-21 | 苏州大学 | A kind of wide covering high-resolution greenhouse gases imaging spectrometer and its application |
| CN109283670A (en) * | 2018-10-25 | 2019-01-29 | 苏州科技大学 | A kind of anti-optical imaging system of off-axis sparse aperture two based on free form surface |
| CN109739013A (en) * | 2018-12-25 | 2019-05-10 | 中国科学院国家天文台南京天文光学技术研究所 | Off-axis three reflecting optical system of big coke ratio wide visual field with real entrance pupil |
| CN111487754A (en) * | 2019-01-25 | 2020-08-04 | 清华大学 | Free-form surface off-axis three-mirror imaging system |
| CN114207394A (en) * | 2019-05-10 | 2022-03-18 | 爱色丽欧洲有限公司 | Illumination device for a spectrophotometer with integrated mixing optics and method for illuminating a sample |
| WO2023077712A1 (en) * | 2021-11-04 | 2023-05-11 | 苏州大学 | Off-axis afocal optical system with large-aperture spherical primary mirror |
| CN116909017A (en) * | 2023-09-13 | 2023-10-20 | 中国科学院长春光学精密机械与物理研究所 | Cooke type spherical image field three-reflection astigmatic telescope design method |
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| CN101435913A (en) * | 2008-12-26 | 2009-05-20 | 苏州大学 | Non-barrier three-reflector optical system |
| CN206224041U (en) * | 2016-11-09 | 2017-06-06 | 苏州大学 | A kind of extremely wide field of view computer-aided alignment |
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| CN101435913A (en) * | 2008-12-26 | 2009-05-20 | 苏州大学 | Non-barrier three-reflector optical system |
| CN206224041U (en) * | 2016-11-09 | 2017-06-06 | 苏州大学 | A kind of extremely wide field of view computer-aided alignment |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107966804A (en) * | 2017-12-30 | 2018-04-27 | 苏州大学 | Four speculum telephotolens of compact long-focus |
| CN108426846A (en) * | 2018-06-14 | 2018-08-21 | 苏州大学 | A kind of wide covering high-resolution greenhouse gases imaging spectrometer and its application |
| CN109283670B (en) * | 2018-10-25 | 2023-09-12 | 苏州科技大学 | Off-axis sparse aperture two-reflection optical imaging system based on free curved surface |
| CN109283670A (en) * | 2018-10-25 | 2019-01-29 | 苏州科技大学 | A kind of anti-optical imaging system of off-axis sparse aperture two based on free form surface |
| CN109739013A (en) * | 2018-12-25 | 2019-05-10 | 中国科学院国家天文台南京天文光学技术研究所 | Off-axis three reflecting optical system of big coke ratio wide visual field with real entrance pupil |
| CN109739013B (en) * | 2018-12-25 | 2021-06-22 | 中国科学院国家天文台南京天文光学技术研究所 | Large-focal-ratio wide-field off-axis three-mirror optical system with real entrance pupil |
| CN111487754B (en) * | 2019-01-25 | 2021-04-23 | 清华大学 | Free-form surface off-axis three-mirror imaging system |
| CN111487754A (en) * | 2019-01-25 | 2020-08-04 | 清华大学 | Free-form surface off-axis three-mirror imaging system |
| CN114207394A (en) * | 2019-05-10 | 2022-03-18 | 爱色丽欧洲有限公司 | Illumination device for a spectrophotometer with integrated mixing optics and method for illuminating a sample |
| WO2023077712A1 (en) * | 2021-11-04 | 2023-05-11 | 苏州大学 | Off-axis afocal optical system with large-aperture spherical primary mirror |
| US11906718B2 (en) | 2021-11-04 | 2024-02-20 | Soochow University | Wide-aperture spherical primary mirror off-axis afocal optical system |
| CN116909017A (en) * | 2023-09-13 | 2023-10-20 | 中国科学院长春光学精密机械与物理研究所 | Cooke type spherical image field three-reflection astigmatic telescope design method |
| CN116909017B (en) * | 2023-09-13 | 2023-11-21 | 中国科学院长春光学精密机械与物理研究所 | Cooke type spherical image field three-reflection astigmatic telescope design method |
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