Large aperture, large field of view catadioptric optical system

Abstract

The application discloses a large-aperture large-field-of-view catadioptric optical system, which comprises a first lens, a second lens, a third lens, a fourth lens, a convex mirror, a fifth lens and a sixth lens. The light of target radiation is incident to the front surface of the fourth lens after passing through the first lens, the second lens and the third lens, is transmitted through the front surface of the fourth lens, reaches the rear surface of the fourth lens, is reflected by the rear surface of the fourth lens, reaches the front surface of the fourth lens again, is reflected by the convex mirror, passes through the fifth lens and the sixth lens in sequence, and is finally converged on an image plane. The application can realize large-aperture, large relative aperture and large field-of-view imaging simultaneously, has the advantages of high energy collection capacity, small volume, good imaging quality and the like, and can be applied to the fields of space target detection, space debris detection, exoplanet detection and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of space optical detection, and particularly relates to a large-aperture and large-field catadioptric optical system. BACKGROUND

[0002] The number of satellites launched by domestic and foreign countries is increasing year by year, especially in recent years, commercial satellite companies have developed rapidly, and the number of microsatellites in the earth orbit has increased several times, so that the earth orbit becomes more and more crowded, and the collision risk of the on-orbit satellite becomes higher. At the same time, a large number of space debris is generated by satellite launching, which brings great hidden dangers to the normal operation of the on-orbit satellite. Therefore, it is of great significance to realize the accurate detection and cataloging of the on-orbit satellite and the space debris for the purpose of ensuring space safety. At present, there are still the following problems in realizing the accurate detection and cataloging of the on-orbit satellite and the space debris: firstly, the aperture of the existing space target detection camera is small, and the high-precision detection of small-size satellites, especially the space debris, cannot be realized; secondly, the field angle of the existing space target detection camera is small, and the high-efficiency detection of satellites and space debris in a large range cannot be realized; thirdly, the imaging quality of the existing space target detection camera is poor, and the detection signal-to-noise ratio of the space target is poor, which seriously restricts the detection accuracy of the space target. SUMMARY

[0003] The technical problem solved by the application is to overcome the shortcomings of the prior art and provide a large-aperture and large-field catadioptric optical system, which has the advantages of large aperture, large relative aperture, large field, low distortion and high imaging quality, and meets the high-efficiency and high-precision detection requirements of small-size satellites and space debris.

[0004] The purpose of the application is achieved by the following technical solutions.

[0005] A large-aperture and large-field catadioptric optical system comprises a first lens, a second lens, a third lens, a fourth lens, a convex mirror, a fifth lens and a sixth lens.

[0006] The light of target radiation is incident on the front surface of the fourth lens after passing through the first lens, the second lens and the third lens, is transmitted through the front surface of the fourth lens, is reflected by the rear surface of the fourth lens, reaches the front surface of the fourth lens again, is reflected by the convex mirror, passes through the fifth lens and the sixth lens in sequence, and is finally converged on an image plane.

[0007] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are all meniscus lenses.

[0008] Preferably, the light transmission areas of the first lens, the second lens, the third lens and the fourth lens are all annular.

[0009] Preferably, the front surface of the fourth lens is a transmission surface, and the back surface of the fourth lens is a reflection surface.

[0010] Preferably, the light passing area of the convex mirror is annular.

[0011] Preferably, the back surface of the first lens, the front surface of the third lens, the front surface of the fourth lens, the front surface of the fifth lens and the back surface of the sixth lens are all six-order aspheric surfaces.

[0012] Preferably, the front surface and the back surface of the first lens, the front surface and the back surface of the second lens, the front surface and the back surface of the third lens, the front surface of the fourth lens, the front surface and the back surface of the fifth lens and the front surface and the back surface of the sixth lens are all coated with anti-reflection film, and the transmittance in the spectrum range of 0.45-0.9 μm is greater than 0.99.

[0013] The back surface of the fourth lens and the convex mirror are both coated with anti-reflection film, and the reflectivity in the spectrum range of 0.45-0.9 μm is greater than 0.99.

[0014] Preferably, the material of the first lens is H-K9L, the material of the second lens is H-ZF52, the material of the third lens is N-SF11, the material of the fourth lens is fused quartz, the base material of the convex mirror is fused quartz, the material of the fifth lens is N-Bk1, and the material of the sixth lens is N-FK51A.

[0015] Compared with the prior art, the present application has the following advantages:

[0016] (1) The system of the present application has the imaging ability of large aperture and large relative aperture, and can realize the imaging of an aperture of 280 mm and a focal length of 344 mm in the spectrum range of 0.45-0.9 μm, thereby solving the problems of small aperture and small relative aperture of the optical system of the current space target detection camera, improving the energy collection ability of the space target detection camera in a wide imaging spectrum range, and improving the detection precision of small size space targets.

[0017] (2) The system of the present application has the imaging ability of large field of view, and the imaging field of view angle reaches 15°x15°, thereby solving the problem of small field of view angle of the optical system of the current space target detection camera and improving the detection efficiency of the space target detection camera.

[0018] (3) The system of the present application has good imaging quality, thereby solving the problems of low energy concentration and large distortion of the optical system of the current space target detection camera, improving the signal-to-noise ratio and contrast of the imaging of the space target detection camera, and improving the detection precision of space targets. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Figure 1 is a large-aperture large-field-of-view catadioptric optical system of the present application;

[0020] Figure 2(a) shows the annular light-transmitting area of ​​the front surface L1-FS of the first lens;

[0021] Figure 2(b) shows the annular light-transmitting area of ​​the rear surface L1-BS of the first lens;

[0022] Figure 3(a) shows the annular light-transmitting area of ​​the front surface L2-FS of the second lens;

[0023] Figure 3(b) shows the annular light-transmitting area of ​​the rear surface L2-BS of the second lens;

[0024] Figure 4(a) shows the annular light-transmitting area on the front surface L3-FS of the third lens;

[0025] Figure 4(b) shows the annular light-transmitting area of ​​the rear surface L3-BS of the third lens;

[0026] Figure 5(a) shows the annular light-transmitting area of ​​the front surface L4-FS of the fourth lens;

[0027] Figure 5(b) shows the annular light-transmitting area of ​​the rear surface L4-BS of the fourth lens;

[0028] Figure 6 This is a diagram of the annular light-transmitting area of ​​the convex reflector of the present invention;

[0029] Figure 7 This is a diagram showing the energy concentration of the optical system of the present invention in each field of view;

[0030] Figure 8 This is a grid distortion diagram of the optical system of the present invention. Detailed Implementation

[0031] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] like Figure 1 As shown, this embodiment provides a large-aperture, wide-field-of-view catadioptric optical system with an aperture of 280mm, a working spectral range of 0.45μm to 0.9μm, a focal length of 344mm, and a field of view of 15°×15°. The system includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a convex mirror L5, a fifth lens L6, a sixth lens L7, and an image plane Image.

[0033] The light rays of the target radiation pass through the first lens L1, the second lens L2 and the third lens L3, are incident to the front surface L4-FS of the fourth lens, are transmitted through the front surface L4-FS of the fourth lens to reach the back surface L4-BS of the fourth lens, are reflected by the back surface L4-BS of the fourth lens to reach the front surface L4-FS of the fourth lens again, are reflected by the convex mirror L5, pass through the fifth lens L6 and the sixth lens L7 in turn, and are finally converged on the image plane Image.

[0034] The light rays of the target radiation pass through the first lens L1, the second lens L2 and the third lens L3, are incident to the front surface L4-FS of the fourth lens, are transmitted through the front surface L4-FS of the fourth lens to reach the back surface L4-BS of the fourth lens, are reflected by the back surface L4-BS of the fourth lens to reach the front surface L4-FS of the fourth lens again, are reflected by the convex mirror L5, pass through the fifth lens L6 and the sixth lens L7 in turn, and are finally converged on the image plane Image.

[0035] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L6 and the sixth lens L7 are all meniscus lenses.

[0036] The light transmission areas of the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are all annular.

[0037] The front surface L4-FS of the fourth lens is a transmission surface, and the back surface L4-BS of the fourth lens is a reflection surface.

[0038] The light transmission area of the convex mirror L5 is annular.

[0039] The back surface L1-BS of the first lens, the front surface L3-FS of the third lens, the front surface L4-FS of the fourth lens, the front surface L6-FS of the fifth lens and the back surface L7-BS of the sixth lens are all six-order aspheric surfaces.

[0040] The front surface L1-FS and the back surface L1-BS of the first lens, the front surface L2-FS and the back surface L2-BS of the second lens, the front surface L3-FS and the back surface L3-BS of the third lens, the front surface L3-FS of the fourth lens, the front surface L6-FS and the back surface L6-BS of the fifth lens and the front surface L7-FS and the back surface L7-BS of the sixth lens are all coated with anti-reflection films, and the transmittance in the spectrum range of 0.45 μm to 0.9 μm is greater than 0.99.

[0041] The back surface L4-BS of the fourth lens and the convex mirror L5 are all coated with anti-reflection films, and the reflectivity in the spectrum range of 0.45 μm to 0.9 μm is greater than 0.99.

[0042] By optimizing the aspheric coefficients, the vertex curvature radii of the lens surfaces and the mirror surfaces and the intervals between the elements, the imaging quality of the optical system approaches the diffraction limit, and the volume of the system is compressed to Φ350.6 mm x 395 mm.

[0043] The material of the first lens is H-K9L, and the front surface and the back surface are both coated with anti-reflection film, and the transmittance in the range of 0.45μm-0.9μm is greater than 99%.

[0044] The material of the second lens is H-ZF52, and the front surface and the back surface are both coated with anti-reflection film, and the transmittance in the range of 0.45μm-0.9μm is greater than 99%.

[0045] The material of the third lens is N-SF11, and the front surface and the back surface are both coated with anti-reflection film, and the transmittance in the range of 0.45μm-0.9μm is greater than 99%.

[0046] The material of the fourth lens is fused quartz, the front surface is coated with anti-reflection film, and the transmittance in the range of 0.45μm-0.9μm is greater than 99%; the back surface is coated with anti-reflection film, and the reflectance in the range of 0.45μm-0.9μm is greater than 99%.

[0047] The base material of the convex mirror is fused quartz, and the surface is coated with anti-reflection film, and the reflectance in the range of 0.45μm-0.9μm is greater than 99%.

[0048] The material of the fifth lens is N-BK1, and the front surface and the back surface are both coated with anti-reflection film, and the transmittance in the range of 0.45μm-0.9μm is greater than 99%.

[0049] The material of the sixth lens is N-FK51A, and the front surface and the back surface are both coated with anti-reflection film, and the transmittance in the range of 0.45μm-0.9μm is greater than 99%.

[0050]

[0051]

[0052] As shown in FIG. 2, the light passing areas of the front surface L1-FS and the back surface L1-BS of the first lens are both annular, FIG. 2(a) is the annular light passing area of the front surface L1-FS, the inner diameter is Φ88mm, and the outer diameter is Φ350.6mm; FIG. 2(b) is the annular light passing area of the back surface L1-BS, the inner diameter is Φ90mm, and the outer diameter is Φ331.2mm.

[0053] As shown in FIG. 3, the light passing areas of the front surface L2-FS and the back surface L2-BS of the second lens are both annular, FIG. 3(a) is the annular light passing area of the front surface L2-FS, the inner diameter is Φ100mm, and the outer diameter is Φ326.6mm; FIG. 3(b) is the annular light passing area of the back surface L2-BS, the inner diameter is Φ100mm, and the outer diameter is Φ307.6mm.

[0054] As shown in Figure 4, the light-transmitting areas of the front surface L3-FS and the rear surface L3-BS of the third lens are both annular. Figure 4(a) shows the annular light-transmitting area of ​​the front surface L3-FS, with an inner diameter of Φ153.4mm and an outer diameter of Φ291.8mm; Figure 4(b) shows the annular light-transmitting area of ​​the rear surface L3-BS, with an inner diameter of Φ160mm and an outer diameter of Φ306.8mm.

[0055] As shown in Figure 5, the light-transmitting areas of the front surface L4-FS and the rear surface L4-BS of the fourth lens are both annular. Figure 5(a) shows the annular light-transmitting area of ​​the front surface L4-FS, with an inner diameter of Φ128.6mm and an outer diameter of Φ290.4mm; Figure 5(b) shows the annular light-transmitting area of ​​the rear surface L4-BS, with an inner diameter of Φ152mm and an outer diameter of Φ294.4mm.

[0056] like Figure 6 As shown, the light-transmitting area of ​​the convex reflector is annular, with an inner diameter of Φ30mm and an outer diameter of Φ159mm.

[0057] like Figure 7 The diagram shows the energy concentration of the optical system of the present invention in each field of view. The energy concentration in each field of view within the range of 16μm×16μm is greater than 0.82.

[0058] like Figure 8 The image shows the grid distortion of the optical system of the present invention, with a maximum distortion of 0.67%.

[0059] This invention provides a system with large-aperture and large relative aperture imaging capabilities, which solves the problems of small aperture and small relative aperture in the optical systems of current space target detection cameras, meeting the high-precision detection requirements for smaller satellites, especially space debris. The system also features a large field-of-view imaging capability, addressing the issue of small field of view in the optical systems of current space target detection cameras, thus meeting the detection performance requirements. Furthermore, the system delivers excellent imaging quality, overcoming the problems of low energy concentration and large distortion in the optical systems of current space target detection cameras, achieving the required signal-to-noise ratio and contrast for space target detection, and meeting the accuracy requirements for space target detection.

[0060] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A large-aperture, large-field-of-view catadioptric optical system, characterized in that, include: First lens (L1), second lens (L2), third lens (L3), fourth lens (L4), convex mirror (L5), fifth lens (L6) and sixth lens (L7); The light rays radiated by the target pass through the first lens (L1), the second lens (L2), and the third lens (L3) and then enter the front surface (L4-FS) of the fourth lens. After being transmitted through the front surface (L4-FS), the light rays reach the rear surface (L4-BS) of the fourth lens. After being reflected by the rear surface (L4-BS), the light rays reach the front surface (L4-FS) of the fourth lens again. After being reflected by the convex mirror (L5), the light rays pass through the fifth lens (L6) and the sixth lens (L7) in sequence, and finally converge on the image plane.

2. The large-aperture, large-field-of-view catadioptric optical system according to claim 1, characterized in that: The first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4), the fifth lens (L6), and the sixth lens (L7) are all meniscus lenses.

3. The large-aperture, large-field-of-view catadioptric optical system according to claim 1, characterized in that: The light-transmitting areas of the first lens (L1), the second lens (L2), the third lens (L3), and the fourth lens (L4) are all annular.

4. The large-aperture, large-field-of-view catadioptric optical system according to claim 3, characterized in that: The front surface (L4-FS) of the fourth lens is the transmission surface, and the rear surface (L4-BS) of the fourth lens is the reflection surface.

5. A large-aperture, large-field-of-view catadioptric optical system according to claim 3, characterized in that: The light-transmitting area of ​​the convex mirror (L5) is annular.

6. A large-aperture, large-field-of-view catadioptric optical system according to any one of claims 1 to 5, characterized in that: The rear surface of the first lens (L1-BS), the front surface of the third lens (L3-FS), the front surface of the fourth lens (L4-FS), the front surface of the fifth lens (L6-FS), and the rear surface of the sixth lens (L7-BS) are all sixth-order aspherical surfaces.

7. A large-aperture, large-field-of-view catadioptric optical system according to any one of claims 1 to 5, characterized in that: The front surface (L1-FS) and rear surface (L1-BS) of the first lens, the front surface (L2-FS) and rear surface (L2-BS) of the second lens, the front surface (L3-FS) and rear surface (L3-BS) of the third lens, the front surface (L4-FS) of the fourth lens, the front surface (L6-FS) and rear surface (L6-BS) of the fifth lens, and the front surface (L7-FS) and rear surface (L7-BS) of the sixth lens are all coated with antireflective coatings, and the transmittance in the 0.45μm to 0.9μm spectral range is greater than 0.

99. The rear surface of the fourth lens (L4-BS) and the convex mirror (L5) are both coated with anti-reflection films, and the reflectivity is greater than 0.99 in the 0.45μm to 0.9μm spectral range.

8. A large-aperture, large-field-of-view catadioptric optical system according to any one of claims 1 to 5, characterized in that: The first lens (L1) is made of H-K9L, the second lens (L2) is made of H-ZF52, the third lens (L3) is made of N-SF11, the fourth lens (L4) is made of fused silica, the substrate material of the convex mirror (L5) is fused silica, the fifth lens (L6) is made of N-Bk1, and the sixth lens (L7) is made of N-FK51A.

Images