A stray light suppression design method for space optical systems

Abstract

The present invention provides a stray light suppression design method for a space optical system, which comprises: step S1, establishing an optical-mechanical model of the space optical system, and setting shading apertures at different positions in the space optical system to meet the requirements of sequential imaging of light; step S2, establishing a set of characteristic imaging light rays according to the parameters of the space optical system and performing optical tracing in the optical-mechanical model; step S3, obtaining the position coordinates of the characteristic imaging light rays on the shading aperture, and obtaining a strict light-transmitting area on the shading aperture to meet the requirements of suppressing stray light. The present invention can achieve strict shading of a single / multiple shading apertures at any position of the optical system by flexibly setting shading apertures at multiple places in the optical system, thereby achieving efficient suppression of stray light and maximally eliminating the interference of non-imaging light on the optical system.

Description

Technical Field

[0001] The invention belongs to the field of space remote sensing, and in particular relates to a stray light suppression design method for a space optical system. Background Art

[0002] Space optical systems are very susceptible to stray light due to their complex working environment. Stray light is one of the important factors that affect the performance and imaging quality of optoelectronic equipment. Stray light refers to non-target imaging light in the optical system that does not participate in imaging and is transmitted to the system image plane, as well as light that propagates through non-optical imaging paths to reach the system image plane. Stray light is very harmful to the optical system. Stray light will not only reduce the signal-to-noise ratio of the detector image plane, making the image of the target unclear, but sometimes even cause the noise signal to completely annihilate the detected target signal, thereby causing the system to detect incorrect targets and affect the detection distance and resolution capability of the entire system. In the prior art, the shading apertures mentioned in the stray light suppression design method for space optical systems are all simple contours such as rectangles or circles, and cannot strictly eliminate stray light. Summary of the invention

[0003] The technical problem to be solved by the present invention is that the existing technology cannot ensure that stray light is effectively eliminated by a shading aperture. A stray light suppression design method for a spatial optical system is proposed. The shading aperture can be flexibly set at multiple locations in the optical system to achieve strict shading of a single / multiple shading apertures at any position of the optical system, thereby achieving efficient suppression of stray light and maximally eliminating the interference of non-imaging light on the optical system.

[0004] To achieve the above-mentioned purpose, the present invention provides a stray light suppression design method for a space optical system, which comprises: step S1, establishing an optomechanical model of the space optical system, and setting shading apertures at different positions in the space optical system to meet the requirements of sequential imaging of light; step S2, establishing a set of characteristic imaging light rays according to the parameters of the space optical system and performing optical tracing in the optomechanical model; step S3, obtaining the position coordinates of the characteristic imaging light rays on the shading aperture, and obtaining a strict light-transmitting area on the shading aperture to meet the requirements of suppressing stray light.

[0005] Preferably, the spatial optical system described in step S1 is a multi-reflection system, which includes a plurality of groups of reflector assemblies and at least one detector.

[0006] Preferably, the shading apertures provided at different positions in the spatial optical system in step S1 are provided at the front end of each of the reflector assemblies and the detector as required to form a combination of shading apertures at multiple positions.

[0007] Preferably, if the incident position coordinates (x, y, z) of a set of characteristic imaging light rays established according to the spatial optical system parameters in step S2 are strictly set according to the entrance pupil boundary sampling, the incident coordinate expression is as follows:

[0008] F 入瞳边界方程 (x,y,z)=0

[0009] Among them, the entrance pupil boundary equation F(x, y, z) needs to be determined according to the actual three-dimensional shape of the entrance pupil.

[0010] Preferably, if the incident position coordinates (x, y, z) of a set of characteristic imaging light rays established according to the parameters of the spatial optical system in step S2 are located at the entrance pupil of the spatial optical system, and the three-dimensional shape of the entrance pupil of the characteristic imaging light rays is circular, then the expression of the incident position coordinates is as follows:

[0011]

[0012] Wherein, (x0, y0, z0) is the coordinate of the center of the entrance pupil of the spatial optical system, the range of the argument θ is [0, 2π], and r(θ) is the distance between the coordinate of the incident position of the characteristic imaging light (x, y, z) and the coordinate of the center of the entrance pupil of the spatial optical system (x0, y0, z0) when the argument is θ.

[0013] Preferably, if the incident direction vector of a set of characteristic imaging light rays established according to the spatial optical system parameters in step S2 is (l, m, n), the calculation equation of the incident direction vector (l, m, n) is as follows:

[0014]

[0015] Among them, α x , α y are the imaging field angles of the spatial optical system in the x and y directions respectively.

[0016] Preferably, considering the needs of practical applications, the actual imaging field angle α in the x direction is x '=α x +0.1°, actual imaging angle α in the y direction y '=α y +0.1°.

[0017] Preferably, the field of view of α is characterized as an angle. If the target height h at a finite distance is provided, the height field of view needs to be converted into the angle field of view through a conversion formula, and the conversion formula is as follows:

[0018] α=arctan(h / f)

[0019] Wherein, f is the focal length of the spatial optical system.

[0020] Preferably, the position coordinates of the optomechanical model of the spatial optical system, the position coordinates of the shading aperture at different positions and a set of characteristic imaging light parameters are configured in the optical design software, and optical tracing is performed to obtain the coordinate information of a set of characteristic imaging light on the surface of the shading aperture through the development environment language.

[0021] Preferably, the strictly light-transmitting area on the shading aperture described in step S3 is obtained by obtaining the coordinate information of the characteristic imaging light on the surface of the shading aperture after completing a set of characteristic imaging ray tracing, and drawing the strictly light-transmitting area in the mechanical design software.

[0022] In summary, compared with the prior art, the stray light suppression design method for a space optical system of the present invention has the following beneficial effects:

[0023] (1) By setting and tracing a set of characteristic imaging rays, it is possible to flexibly set a light-shielding aperture with a strict light-transmitting area at any place in the optical system;

[0024] (2) The present invention provides a stray light suppression design method for a space optical system, which can obtain a shading aperture with a strict light transmission area, thereby solving the problem that when suppressing stray light in the optical path, stray light outside the optical path cannot be efficiently suppressed. The method has the advantages of high calculation accuracy and strong engineering feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flowchart of the steps of the stray light suppression design method provided by the present invention;

[0026] Figure 2 It is a schematic diagram of the stray light suppression design provided by the present invention;

[0027] Figure 3 is an optomechanical model of a spatial optical system provided in an embodiment of the present invention;

[0028] Figure 4 Schematic diagram of a light-shielding aperture with a strict light-transmitting area after the stray light suppression design provided in an embodiment of the present invention is completed, wherein:

[0029] (a) is a light shielding stop with a strict light transmission area at the front end of the first reflector 1;

[0030] (b) is a light shielding stop with a strict light transmission area at the front end of the second reflector 2;

[0031] (c) is a light shielding stop with a strict light transmission area at the front end of the third reflector 3;

[0032] (d) is a light shielding stop with a strict light transmission area at the front end of the fourth reflector 4;

[0033] (e) is the light-shielding aperture with a strict light-clearance area at the front end of the detector. DETAILED DESCRIPTION

[0034] The following will be combined with the attached embodiment of the present invention Figure 1 ~Attached Figure 4 , the technical solutions, structural features, objectives achieved and effects in the embodiments of the present invention are described in detail.

[0035] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only the elements explicitly listed, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0036] The present invention provides a stray light suppression design method for a space optical system, such as Figure 1 As shown, it includes: step S1, establishing an optomechanical model of a spatial optical system, and setting shading apertures at different positions in the spatial optical system to meet the requirement of sequential imaging of light; step S2, establishing a set of characteristic imaging light rays according to the parameters of the spatial optical system and performing optical tracing in the optomechanical model; step S3, obtaining the position coordinates of the characteristic imaging light rays on the shading aperture, and obtaining a strict light-transmitting area on the shading aperture to meet the requirement of suppressing stray light.

[0037] Among them, in step S1, if Figure 2 As shown, the space optical system is selected as a multi-reflection system, including multiple groups of mirror assemblies and at least one detector. The shading apertures arranged at different positions in the space optical system are arranged at the front end of each of the mirror assemblies and the detector as needed to form a combination of shading apertures at multiple positions.

[0038] The optical-mechanical model of the spatial optical system includes a reflector assembly and a detector (such as Figure 2 As shown), the reflector assembly includes a camera lens, a reporting optical lens, and a structural member supporting the optical lens.

[0039] Furthermore, if the incident position coordinates (x, y, z) of a set of characteristic imaging light rays established according to the spatial optical system parameters in step S2 are strictly set according to the entrance pupil boundary sampling, the incident coordinate expression is as follows:

[0040] F 入瞳边界方程(x,y,z)=0

[0041] Among them, the entrance pupil boundary equation F(x, y, z) needs to be determined according to the actual three-dimensional shape of the entrance pupil.

[0042] Further, if the incident position coordinates (x, y, z) of a set of characteristic imaging light rays established according to the spatial optical system parameters in step S2 are located at the entrance pupil of the spatial optical system, and the three-dimensional shape of the entrance pupil of the characteristic imaging light rays is circular, then the expression of the incident position coordinates is as follows:

[0043]

[0044] Wherein, (x0, y0, z0) is the coordinate of the center of the entrance pupil of the spatial optical system, the range of the argument θ is [0, 2π], and r(θ) is the distance between the coordinate of the incident position of the characteristic imaging light (x, y, z) and the coordinate of the center of the entrance pupil of the spatial optical system (x0, y0, z0) when the argument is θ.

[0045] Further, if the incident direction vector of a set of characteristic imaging rays established according to the spatial optical system parameters in step S2 is (l, m, n), the calculation equation of the incident direction vector (l, m, n) is as follows:

[0046]

[0047] Among them, α x , α y are the imaging field angles of the spatial optical system in the x and y directions, respectively. Considering the needs of practical applications, the actual imaging field angle α in the x direction x '=α x +0.1°, actual imaging angle α in the y direction y '=α y +0.1°. By combining the actual imaging angles in the x and y directions with the calculation equation, the incident direction vector (l, m, n) can be calculated, that is, the vector cosine of the characteristic imaging light in the x, y, and z directions can be obtained.

[0048] It should be noted that α x ,α y The field of view is characterized as an angle. If the target height h at a finite distance is provided, the height field of view needs to be converted into the angle field of view through a conversion formula. The conversion formula is as follows:

[0049] α=arctan(h / f)

[0050] Wherein, f is the focal length of the spatial optical system.

[0051] Furthermore, the position coordinates of the optical-mechanical model of the spatial optical system (i.e., the position coordinates of the reflector assembly and the detector), the position coordinates of the light-shielding aperture at different positions, and a set of characteristic imaging light parameters (i.e., the incident direction vector (l, m, n)) are configured in the optical design software ZEMAX, and optical tracing is performed to obtain a set of characteristic imaging light coordinate information on the light-shielding aperture surface through the Visual Studio development environment language. In other embodiments, lighttools can also be selected as the optical design software; for the development environment language, python can also be selected to obtain a set of characteristic imaging light coordinate information on the light-shielding aperture surface.

[0052] The strict light-transmitting area on the shading aperture described in step S3 is obtained by tracing a set of characteristic imaging rays to obtain the coordinate information of the characteristic imaging rays on the surface of the shading aperture, and the strict light-transmitting area is drawn in the mechanical design software SolidWorks to generate a shading aperture with a strict light-transmitting area (such as Figure 4 shown).

[0053] The following is further described based on specific embodiments:

[0054] According to step S1, Figure 3 As shown, the spatial optical system in this embodiment is a four-reflection optical system, that is, it includes a first reflector 1, a second reflector 2, a third reflector 3, a fourth reflector 4 and a detector. As needed, shading apertures 6 are set at multiple positions at the front end of the first reflector 1, the second reflector 2, the third reflector 3, the fourth reflector 4 and the detector 5.

[0055] According to step S2, since the three-dimensional shape of the entrance pupil in this embodiment is circular, the incident position coordinates (x, y, z) of a set of characteristic imaging rays are strictly set according to the sampling of the circular entrance pupil boundary, and the incident coordinate expression is:

[0056] (x+21699) 2 +(y-41727) 2 +z 2 =r 2

[0057] That is to say, this equation can be used to express that the entrance pupil boundary equation of this embodiment is a circle.

[0058] Further, according to step S2, the incident position coordinates (x, y, z) of a group of characteristic imaging light rays whose entrance pupil three-dimensional shape is circular are located at the entrance pupil of the optical system, and the expressions of the incident position coordinates are as follows:

[0059]

[0060] Wherein, (x0, y0, z0) represents the coordinates of the center of the entrance pupil of the optical system. In this embodiment, (x0, y0, z0) = (-21699, 41727, 0), the value range of the angle θ is [0, 2π], and r(θ) is the distance between the coordinates of the incident position of the characteristic imaging light (x, y, z) and the coordinates of the center of the entrance pupil of the optical system (-21699, 41727, 0) when the angle takes the value θ. In this embodiment, r(θ) = r = 200 mm, which is half of the entrance pupil diameter of the optical system of 400 mm.

[0061] Further, according to step S2, if the incident direction vector of a set of characteristic imaging light rays whose entrance pupil three-dimensional shape is a circle is (l, m, n), the calculation equation of the incident direction vector (l, m, n) is as follows:

[0062]

[0063] Among them, α x , α y are the imaging field angles of the spatial optical system in the x direction and the y direction, respectively. In this embodiment, α x =40°, α y =1°, considering the needs of practical applications, the actual imaging field angle α in the x direction x '=α x +0.1°, or α x '=40°+0.1°=40.1°, the actual imaging field angle α in the y direction y '=α y +0.1°, or α y '=1°+0.1°=1.1°, and then we can get the incident direction vector (l,m,n), that is, we can get the vector cosine of the characteristic imaging light in the x, y, and z directions.

[0064] According to step S1 and step S2, the position coordinates of the optomechanical model of the spatial optical system, the position coordinates of the shading aperture at different positions and a set of characteristic imaging light parameters are configured in the optical design software ZEMAX, and optical tracing is performed to obtain the coordinate information of a set of characteristic imaging light on the surface of the shading aperture through the Visual Studio development environment language.

[0065] According to step S3, the coordinate information of the characteristic imaging light on the surface of the shading aperture obtained in step S2 is input into the mechanical design software SolidWorks to draw the strict light-transmitting area, and the shading aperture 6 with a strict light-transmitting area at the front end of the first reflector 1, the second reflector 2, the third reflector 3, the fourth reflector 4 and the detector 5 is obtained (such as Figure 4 As shown), the stray light suppression design is completed.

[0066] In summary, compared with the prior art, the stray light suppression design method for a space optical system provided by the present invention can set a shading aperture with a strict light-transmitting area at any place in the space optical system, and at the same time solves the problem that when suppressing stray light in the optical path, stray light outside the optical path cannot be efficiently suppressed. It has the advantages of high calculation accuracy and strong engineering feasibility.

[0067] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as limiting the present invention. After reading the above content, a variety of modifications and substitutions of the present invention will be obvious to those skilled in the art, such as the expression of the optical system entrance pupil boundary equation, the tilt rotation of the optical system entrance pupil, the type of optical machine design software used, etc. Therefore, the protection scope of the present invention should be defined by the attached claims.

Claims

1. A stray light suppression design method for a space optical system, characterized in that: include: Step S1, establishing an optical-mechanical model of a spatial optical system, and setting light-shielding apertures at different positions in the spatial optical system to meet the requirement of sequential imaging of light rays; Step S2, establishing a set of characteristic imaging rays according to the spatial optical system parameters and performing optical tracing in the optomechanical model; Step S3, obtaining the position coordinates of the characteristic imaging light on the light-shielding aperture, and obtaining a strict light-transmitting area on the light-shielding aperture to meet the requirement of suppressing stray light; Wherein, the spatial optical system described in step S1 is selected as a multi-reflection system, which includes multiple groups of reflector components and at least one detector; Wherein, the shading apertures provided at different positions in the spatial optical system in step S1 are provided at the front end of each of the reflector assemblies and the detector as required to form a combination of shading apertures at multiple positions; Wherein, step S2 specifically includes: configuring the position coordinates of the optical-mechanical model of the spatial optical system, the position coordinates of the shading aperture at different positions, and a set of characteristic imaging light parameters in the optical design software, and performing optical tracing to obtain the coordinate information of a set of characteristic imaging light on the surface of the shading aperture through the development environment language; Among them, the strict light-transmitting area on the shading aperture described in step S3 is obtained by obtaining the coordinate information of the characteristic imaging light on the surface of the shading aperture after a set of characteristic imaging light tracing is completed, and the strict light-transmitting area is drawn in the mechanical design software.

2. The stray light suppression design method for a space optical system according to claim 1, characterized in that: If the incident position coordinates (x, y, z) of a set of characteristic imaging light rays established according to the spatial optical system parameters in step S2 are strictly set according to the entrance pupil boundary sampling, the incident position coordinate expression is as follows: F 入瞳边界方程 (x,y,z)=0 Among them, the entrance pupil boundary equation F(x, y, z) needs to be determined according to the actual three-dimensional shape of the entrance pupil.

3. The stray light suppression design method for a space optical system according to claim 1, characterized in that: If the incident position coordinates (x, y, z) of a set of characteristic imaging light rays established according to the spatial optical system parameters in step S2 are located at the entrance pupil of the spatial optical system, and the three-dimensional shape of the entrance pupil of the characteristic imaging light rays is circular, then the expression of the incident position coordinates is as follows: Wherein, (x0, y0, z0) is the coordinate of the center of the entrance pupil of the spatial optical system, the range of the argument θ is [0, 2π], and r(θ) is the distance between the coordinate of the incident position of the characteristic imaging light (x, y, z) and the coordinate of the center of the entrance pupil of the spatial optical system (x0, y0, z0) when the argument is θ.

4. The stray light suppression design method for a space optical system according to claim 1, characterized in that: If the incident direction vector of a set of characteristic imaging light rays established according to the spatial optical system parameters in step S2 is (l, m, n), then the calculation equation of the incident direction vector (l, m, n) is as follows: Among them, α x , α y are the imaging field angles of the spatial optical system in the x and y directions respectively.

5. The stray light suppression design method for a space optical system according to claim 4, characterized in that: Considering the needs of practical applications, the actual imaging field angle α in the x direction x '=α x +0.1°, actual imaging angle α in the y direction y '=α y +0.1°.

6. The stray light suppression design method for a space optical system according to claim 4, characterized in that: The field of view of α is represented by an angle. If the target height h at a finite distance is provided, the height field of view needs to be converted into the angle field of view through a conversion formula. The conversion formula is as follows: α=arctan(h / f) Wherein, f is the focal length of the spatial optical system.

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