CN113238368A - Folding-axis three-reflection telescope objective lens without secondary blocking surface view field - Google Patents
Folding-axis three-reflection telescope objective lens without secondary blocking surface view field Download PDFInfo
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- CN113238368A CN113238368A CN202110538000.7A CN202110538000A CN113238368A CN 113238368 A CN113238368 A CN 113238368A CN 202110538000 A CN202110538000 A CN 202110538000A CN 113238368 A CN113238368 A CN 113238368A
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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
- G02B17/082—Catadioptric systems using three curved mirrors
- G02B17/0832—Catadioptric systems 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
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/02—Telephoto objectives, i.e. systems of the type + - in which the distance from the front vertex to the image plane is less than the equivalent focal length
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
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- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
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Abstract
The invention relates to a folding axis three-reflex telescopic objective lens without secondary blocking, which comprises: the device comprises a primary mirror, a secondary mirror, a tertiary mirror, a deflection reflecting mirror and a focal plane; the rotation symmetry axes of the primary mirror, the secondary mirror and the third mirror are not on the same axis, and the aperture diaphragm is arranged on the primary mirror. The surface shape of the primary mirror is an ellipsoid, and the shapes of the secondary mirror and the tertiary mirror are hyperboloids. The deflection reflector is positioned on an emergent light path of the three mirrors and is inclined relative to the three mirrors so as to lead an image plane out of an optical axis to facilitate the installation of the detector. The primary mirror and the secondary mirror form a middle real image and are close to the exit pupil, so that the secondary blocking generated by the deflection reflector is avoided. The invention realizes the design of the three-mirror telescope objective without secondary blocking and folding axis through the tiny eccentricity and inclination. The invention keeps a similar mechanical structure, but the field of view is relatively enlarged, the invention has the advantages of compact structure and small volume, meets the requirement of miniaturization, introduces small eccentricity and inclination, has image quality close to the diffraction limit and small stray light influence, and is suitable for the optical imaging fields of area-array cameras, imaging spectrometer front-mounted systems and the like.
Description
Technical Field
The invention relates to a telescopic objective lens which can be used for a front objective lens of an area-array camera and an imaging spectrometer, in particular to a three-reflection telescopic objective lens without a secondary blocking folding axis, and belongs to the technical field of imaging optics.
Background
To acquire high-resolution images of the ground, a long-focus telescopic objective lens is generally used. In order to reduce development and emission costs, miniaturization while satisfying high resolution is required, which puts higher demands on the design of a telescopic objective lens. Common telescopic objectives can be generally classified into three types, i.e., transmission type, refraction and reflection type. The transmission system is easy to process and adjust, but is sensitive to chromatic aberration and temperature, and is difficult to be applied to a wide band. The catadioptric system is configured by adding a lens correction group to the two-mirror structure to correct the off-axis aberration, but requires a long lens hood to suppress stray light, and is difficult to be miniaturized. The reflection type system is free of chromatic aberration, simple in structure and insensitive to temperature, and is widely applied to high-resolution satellite-borne cameras. The coaxial three-mirror structure and the off-axis three-mirror structure are widely adopted at present. The coaxial triple-reflection structure usually adopts a deflection reflector to provide space for installing a detector, and needs to avoid secondary blocking. The adoption of a partial visual field three-inverse structure can avoid secondary blocking, but only can image a one-dimensional linear visual field, and the other-dimensional visual field is difficult to enlarge. The other coaxial three-mirror structure adopts annular field imaging, the primary mirror and the secondary mirror form a primary intermediate real image, light rays reflected by the three mirrors are made to be incident on the deflection reflector without secondary blocking by sacrificing the field of view in the center part, and partial field energy is lost. In order to enlarge the view field, an off-axis three-mirror structure is adopted, no central blocking exists, image space telecentricity is easy to realize, but the problems of high processing and debugging difficulty, large size of a system in the vertical direction and the like exist.
Disclosure of Invention
The invention solves the problems: aiming at the defects in the prior art, the folding-axis three-reflection telescope objective lens is long in focal length, small in size, compact in structure, suitable for wide wave bands and capable of achieving two-dimensional surface view field imaging and is free of secondary blocking.
The technical scheme of the invention is to provide a feasible folding axis three-reflection telescope objective without secondary blocking, which comprises a main mirror, a secondary mirror, a third mirror, a deflection reflector and a focal plane. The primary mirror is an ellipsoid surface, the secondary mirror and the tertiary mirror are hyperboloids, the focal powers of the primary mirror and the tertiary mirror are positive, and the focal power of the secondary mirror is negative; the telescope objective lens is provided with a middle real image surface, and the rotation symmetry axes of the primary mirror, the secondary mirror and the three mirrors are not coaxial. The entrance pupil of the optical system is positioned at the main mirror, and the deflection reflector is positioned near the exit pupil; incident light from a ground target is reflected by the primary mirror and the secondary mirror in sequence, a real image is formed between the secondary mirror and the three mirrors, the real image is reflected by the three mirrors, the reflected light enters the deflection mirror without being blocked, and a target image is formed at a focal plane after the reflected light is reflected by the deflection mirror.
The telescope objective lens provided by the invention reserves the primary obscuration of the secondary lens, takes the eccentricity and the inclination of the primary lens as free variables, increases the degree of freedom compared with the traditional coaxial triple-lens system, is beneficial to expanding the view field in the meridian direction and avoids the secondary obscuration. Wherein the eccentricity of the main mirror is 20-40 mm, and the inclination is 0.5-3 degrees; the eccentricity of the secondary mirror is 1 mm-20 mm, and the inclination is 0.5-3 degrees; the eccentricity of the three mirrors is 1 mm-20 mm, the inclination is 2-7 degrees, and the parameters are obtained by a great deal of research and experiments of the applicant.
The field diaphragm is arranged at the middle primary real image of the telescopic objective lens provided by the invention.
The working waveband of the telescopic objective lens provided by the invention is suitable for a wider waveband range from ultraviolet to infrared.
Compared with the prior art, the invention has the advantages that:
(1) compared with a coaxial three-reflector telescope objective, the telescope objective provided by the invention has a similar mechanical structure form, primary obscuration of the secondary lens is reserved, the field of view in the meridional direction is relatively improved, and no secondary obscuration exists.
(2) Compared with the traditional off-axis three-mirror telescopic objective lens, the main lens of the telescopic objective lens provided by the invention does not need to process a large-caliber main lens, so that the processing and development cost is reduced. Secondly, the overall structure size reduces, and the structure is compacter to the processing dress accent degree of difficulty has been reduced.
(3) The stray light inhibition performance is good, an outer light shield is not needed, and the volume is further reduced.
Drawings
Fig. 1 is a schematic view of an optical path structure of a telescopic objective lens provided in an embodiment of the present invention;
FIG. 2 is a modulation transfer function curve of a telescopic objective lens provided by an embodiment of the present invention;
FIG. 3 is a diagram of a light trace point array of a telescopic objective lens according to an embodiment of the present invention;
FIG. 4 is a diagram of the distortion of the objective lens grid for telescopic lens according to the embodiment of the present invention;
in fig. 1: 1. a primary mirror and an aperture stop; 2. a secondary mirror; 3. three mirrors; 4. a deflecting mirror; 5. a focal plane.
Detailed Description
The following figures further illustrate the technical solution of the present invention in detail with reference to the accompanying drawings and examples.
The invention discloses a three-reflection telescope objective without a secondary blocking folding shaft, which solves the problems of secondary blocking and difficult detector installation of opposite view field imaging of the conventional three-reflection telescope objective. The device comprises a primary mirror 1, a secondary mirror 2, a three-mirror 3, a deflection reflecting mirror 4 and a focal plane 5. The rotation symmetry axes of the primary mirror 1, the secondary mirror 2 and the three mirrors 3 are not on the same axis, and the aperture diaphragm is arranged on the primary mirror 1. The surface shape of the primary mirror 1 is an ellipsoid, and the surface shapes of the secondary mirror 2 and the tertiary mirror 3 are hyperboloids. The deflecting reflector 4 is positioned on the emergent light path of the three mirrors 3, and is inclined relative to the three mirrors 3 so as to lead the image plane out of the optical axis and facilitate the installation of the detector. The primary mirror 1 and the secondary mirror 2 form a middle real image close to the exit pupil, so that the secondary blocking of the deflection reflector is avoided. The structure provided by the invention realizes the design of the three-reflection telescope objective without secondary blocking folding axis through tiny eccentricity and inclination. Compared with a coaxial three-reflex telescopic objective lens, a similar mechanical structure is maintained, but the field of view is relatively increased. Compared with the traditional off-axis three-reflector telescope objective, the three-reflector telescope objective has compact structure and small volume, meets the requirement of miniaturization, has small introduced eccentricity and inclination, has image quality close to the diffraction limit and small stray light influence, and is particularly suitable for the optical imaging fields of area-array cameras, imaging spectrometer front-mounted systems and the like.
The invention provides a folding-axis three-reflex telescopic objective lens without secondary blocking, which is characterized in that the design parameters are as follows: the focal length is 1200mm, the full field angle is 2.4 degrees multiplied by 1.7 degrees, the F number is 7, and the working wave band is 420 nm-780 nm.
As shown in fig. 1, an optical path structure of a telescopic objective lens provided in an embodiment of the present invention is schematically illustrated. The rotation symmetry axes of the primary mirror 1, the secondary mirror 2 and the tertiary mirror 3 are not coaxial, and the aperture diaphragm is positioned at the primary mirror 1. Incident light from a ground target is reflected by the primary mirror 1 and the secondary mirror 2 in sequence, a real image is formed between the secondary mirror 2 and the third mirror 3, the real image is reflected by the third mirror 3, the reflected light enters the deflection reflector 4 without being blocked, and a target image is formed at a focal plane 5 after the reflected light is reflected by the deflection reflector.
The main structural parameters of the telescopic objective lens provided by the embodiment of the invention are listed in table 1, and the eccentricity and the inclination of each reflector are listed in table 2. The focal power of the primary mirror and the tertiary mirror is positive, the focal power of the secondary mirror 2 is negative, the primary mirror is an ellipsoid, and the secondary mirror and the tertiary mirror are hyperboloids. The main mirror has the largest clear aperture of 172mm, and the diameter of the central hole is 58 mm. The total optical length is 270mm, which is about 1/4.4 of the focal length. The angle of inclination of the deflecting mirror with respect to the three mirrors is 17 °.
TABLE 1 folding axis triple-reflection telescope objective lens construction parameters
TABLE 2 decentering and tilting of the mirrors
Referring to fig. 2, Modulation Transfer Function (MTF) curves of the telescopic objective lens provided by the embodiment of the present invention at the fields of view (0 ° ), (0 °, 0.85 °), (1.2 °, 0 °), (1.2 °, 0.85 °), (-1.2 °, -0.85 °), (-1.2 °, 0 °), (0 °, -0.85 °), and (-1.2 °, 0.85 °). In the figure, the abscissa represents spatial frequency and the ordinate represents MTF. As can be seen, the marginal field MTF value is 0.34 at the detector Nyquist frequency, and the imaging quality is close to the diffraction limit.
Referring to fig. 3, which is a dot diagram of the telescopic objective lens provided in this embodiment at the fields of view (0 ° ), (0 °, 0.85 °), (1.2 °, 0 °), (1.2 °, 0.85 °), (-1.2 °, -0.85 °), (-1.2 °, 0 °), (0 °, -0.85 °), and (-1.2 °, 0.85 °), black circles in the figure represent diffraction-limited airy spots. As can be seen from the figure, most energy of the diffuse speckles in each field of view is concentrated in the range of the Airy spots, and the telescopic objective lens has good imaging quality.
Referring to fig. 4, which is a diagram of the distortion of the grid of the telescopic objective lens provided in this embodiment, according to the calculation, the maximum distortion is 1.53%, and can be corrected by the later geometric calibration.
The above examples are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the invention is defined by the appended claims. Various equivalent substitutions and modifications can be made without departing from the spirit and principles of the invention, and are intended to be within the scope of the invention.
Claims (6)
1. A kind of three-reflection telescope objective of visual field of no secondary obscuration surface, characterized by including: a primary mirror (1), a secondary mirror (2), a tertiary mirror (3), a deflection reflecting mirror (4) and a focal plane (5); the primary mirror (1) is an ellipsoid, the secondary mirror (2) and the third mirror (3) are hyperboloids, the focal powers of the primary mirror (1) and the third mirror (3) are positive, and the focal power of the secondary mirror (2) is negative; the telescope objective lens is provided with a middle primary real image surface, and the rotation symmetry axes of the primary mirror (1), the secondary mirror (2) and the three mirrors are not coaxial; the entrance pupil of the telescope objective is positioned at the main mirror (1), and the deflection reflector (4) is positioned near the exit pupil; incident light from a ground target is reflected by the primary mirror (1) and the secondary mirror (2) in sequence, a primary real image is formed between the secondary mirror (2) and the three mirrors (3), the incident light is reflected by the three mirrors (3), the reflected light enters the deflection reflector (4) without being blocked, and a target image is formed at a focal plane (5) after the reflected light is reflected by the deflection reflector (4).
2. The fold-axis triple-reflex telescopic objective lens without the secondary obscuration as claimed in claim 1, wherein: relative to the incident light direction of the primary mirror (1), the eccentricity of the primary mirror (1) is 20-40 mm, and the inclination is 0.5-3 degrees.
3. The fold-axis triple-reflex telescopic objective lens without the secondary obscuration as claimed in claim 1, wherein: relative to the incident light direction of the secondary mirror (2), the eccentricity of the secondary mirror (2) is 1-20 mm, and the inclination is 0.5-3 degrees.
4. The fold-axis triple-reflex telescopic objective lens without the secondary obscuration as claimed in claim 1, wherein: the three mirrors (3) have the eccentricity of 1-20 mm and the inclination of 2-7 degrees relative to the incident light direction.
5. The fold-axis triple-reflex telescopic objective lens without the secondary obscuration as claimed in claim 1, wherein: and placing a field diaphragm at the middle primary real image.
6. The fold-axis triple-reflex telescopic objective lens without the secondary obscuration as claimed in claim 1, wherein: the working waveband of the three-reflection telescope objective without the secondary blocking folding shaft is suitable for ultraviolet to infrared.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110538000.7A CN113238368B (en) | 2021-05-18 | 2021-05-18 | Non-secondary blocking surface view field folded-axis three-mirror telescope objective lens |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110538000.7A CN113238368B (en) | 2021-05-18 | 2021-05-18 | Non-secondary blocking surface view field folded-axis three-mirror telescope objective lens |
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| CN113238368A true CN113238368A (en) | 2021-08-10 |
| CN113238368B CN113238368B (en) | 2023-08-25 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115980996A (en) * | 2022-11-28 | 2023-04-18 | 中国科学院长春光学精密机械与物理研究所 | Design method of space gravitational wave telescope |
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| US5631770A (en) * | 1994-05-26 | 1997-05-20 | Hughes Danbury Optical Systems, Inc. | Reflective scanning telescopic system on single optical bench |
| CN102023375A (en) * | 2009-09-11 | 2011-04-20 | 中国科学院西安光学精密机械研究所 | Folding axis three-reflector optical system with long focal length, no distortion and flat image field |
| CN102323671A (en) * | 2011-09-14 | 2012-01-18 | 中国科学院长春光学精密机械与物理研究所 | Telecentric off-axis three-mirror optical imaging system with real entrance pupil |
| US9134518B1 (en) * | 2010-09-23 | 2015-09-15 | Lockheed Martin Corporation | Multiple-sensor common-interface telescope |
| CN105204148A (en) * | 2015-10-15 | 2015-12-30 | 苏州大学 | Coaxial three-reflection telescope objective for planar view field without secondary blocking |
| CN106371200A (en) * | 2016-11-09 | 2017-02-01 | 苏州大学 | Broad wave band, large view field and large aperture coude three reflection afocal optical system |
| US20180180898A1 (en) * | 2016-12-22 | 2018-06-28 | Tsinghua University | Freeform surface off-axial three-mirror image-side telecentric optical system |
-
2021
- 2021-05-18 CN CN202110538000.7A patent/CN113238368B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5631770A (en) * | 1994-05-26 | 1997-05-20 | Hughes Danbury Optical Systems, Inc. | Reflective scanning telescopic system on single optical bench |
| CN102023375A (en) * | 2009-09-11 | 2011-04-20 | 中国科学院西安光学精密机械研究所 | Folding axis three-reflector optical system with long focal length, no distortion and flat image field |
| US9134518B1 (en) * | 2010-09-23 | 2015-09-15 | Lockheed Martin Corporation | Multiple-sensor common-interface telescope |
| CN102323671A (en) * | 2011-09-14 | 2012-01-18 | 中国科学院长春光学精密机械与物理研究所 | Telecentric off-axis three-mirror optical imaging system with real entrance pupil |
| CN105204148A (en) * | 2015-10-15 | 2015-12-30 | 苏州大学 | Coaxial three-reflection telescope objective for planar view field without secondary blocking |
| CN106371200A (en) * | 2016-11-09 | 2017-02-01 | 苏州大学 | Broad wave band, large view field and large aperture coude three reflection afocal optical system |
| US20180180898A1 (en) * | 2016-12-22 | 2018-06-28 | Tsinghua University | Freeform surface off-axial three-mirror image-side telecentric optical system |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115980996A (en) * | 2022-11-28 | 2023-04-18 | 中国科学院长春光学精密机械与物理研究所 | Design method of space gravitational wave telescope |
| CN115980996B (en) * | 2022-11-28 | 2024-04-30 | 中国科学院长春光学精密机械与物理研究所 | Design method of space gravitational wave telescope |
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