Common-aperture double-linear-array surveying and mapping camera optical system based on secondary mirror multiplexing

Abstract

The invention relates to a common-aperture double-linear-array surveying and mapping camera optical system based on secondary mirror multiplexing, and belongs to the technical field of space remote sensing measurement. The optical system comprises two double-line-scan digital cameras which share the same aperture diaphragm and the same main reflector. According to the optical system, an integrated structure that the double-line-scan digital camera shares the primary mirror and a structure that the secondary mirror and the fourth mirror are coplanar and most of effective areas are overlapped are adopted at the same time, the double-line-scan digital camera is subjected to integrated structure design, the measurement precision regulation and control difficulty is reduced, and the surveying and mapping precision is improved; and a free-form surface is also introduced to realize coplanarity of the secondary mirror and the fourth mirror, so that two reflection areas of the coplanar reflector are overlapped, and the volume and the mass of the coplanar reflector are reduced. On the basis that three reflectors of the optical system are reduced, the focal plane is placed between the main reflector and the third reflector, light is overlapped on the premise that the image quality is not reduced, the size of the optical system is compressed, the space utilization rate of the system is improved, and the emission cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of aerospace remote sensing measurement technology, and in particular to a common-aperture dual-line array mapping camera optical system based on secondary mirror multiplexing. Background Art

[0002] Surveying and mapping plays a key role in promoting economic development, optimizing urban layout, strengthening national defense, and managing natural resources. Mapping satellites' ground imaging technology enables precise data capture of the morphology, size, spatial distribution, and related data of natural features and man-made structures. Currently, many countries around the world have prioritized high-resolution optical mapping satellites and their applications, striving to improve the accuracy and efficiency of surveying and mapping technology.

[0003] In the field of aerospace remote sensing, surveying and mapping satellites typically employ a dual- or triple-camera architecture, leveraging multi-view imaging to accomplish three-dimensional spatial measurement tasks. However, this multi-device integration approach not only significantly increases the weight and size of the satellite payload but also presents a series of engineering challenges. Among these challenges, precise mechanical stability matching between imaging units is difficult, and controlling measurement accuracy is challenging. Especially under temperature fluctuations, thermal deformation of the individual optical components can cause deviations from the principal optical axis and alter internal parameters, negatively impacting image quality and measurement accuracy. With the continuous advancement of aerospace technology, the technical limitations of this space measurement approach, which utilizes a separate optical-mechanical structure, are gradually becoming apparent. Therefore, it is necessary to design an integrated, compact dual-line array mapping camera that not only reduces the camera's size and weight, but also simplifies the control of the camera's measurement accuracy, thereby improving the accuracy of surveyed images. Summary of the Invention

[0004] This invention aims to address the technical issues of existing separate dual-line array mapping cameras, such as their bulk and mass, and the difficulty in controlling the measurement accuracy between the independent optical components. It provides a common-aperture dual-line array mapping camera optical system based on secondary mirror reuse. This invention integrates the optical system of the dual-line array cameras into a single design, achieving a unified optical system by designing the two cameras with a common aperture.

[0005] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0006] A common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing, comprising: two dual-line array cameras sharing the same aperture stop and primary reflector;

[0007] Each of the dual-line array cameras further comprises: a secondary four-coplanar reflector, a third reflector and a focal plane;

[0008] The main reflector serves as the first reflective surface of one dual-line array camera and also serves as the first reflective surface of another dual-line array camera;

[0009] The secondary four-coplanar reflector of each dual-line array camera serves as the second and fourth reflective surfaces of the dual-line array camera and is coaxially arranged with the primary reflector. The optically effective use area of ​​the second reflective surface covers the upper and lower parts of the secondary four-coplanar reflector, and the optically effective use area of ​​the fourth reflective surface is located in the upper half or lower half of the secondary four-coplanar reflector, and the two optically effective use areas partially overlap. The third reflector serves as the third reflective surface of the dual-line array camera and is coaxially arranged with the primary reflector and the secondary four-coplanar reflector, and is on the reflection light path of the secondary four-coplanar reflector. The focal plane is located between the primary reflector and the third reflector.

[0010] In the above technical solution, the secondary four-coplanar reflector is an off-axis four-mirror system in which the secondary mirror and the four mirrors are arranged to coincide with each other in the center position and have the same surface parameters.

[0011] In the above technical solution, the common-aperture dual-line array mapping camera optical system based on secondary mirror multiplexing adopts an off-axis field of view configuration. In one of the dual-line array cameras, the central field of view is deflected 11.25° counterclockwise relative to the optical axis, and in the other dual-line array camera, the central field of view is deflected 11.25° clockwise relative to the optical axis.

[0012] In the above technical solution, the field of view of one of the dual-line array cameras is a rectangular field of view, with a full field of view of 6°×0.5°, a field of view range in the meridional direction of 11° to 11.5°, and a field of view range in the sagittal direction of -3° to 3°; the field of view of the other dual-line array camera is a rectangular field of view, with a full field of view of 6°×0.5°, a field of view range in the meridional direction of -11° to -11.5°, and a field of view range in the sagittal direction of -3° to 3°.

[0013] In the above technical solution, the primary reflector, the secondary four-coplanar reflector, and the third reflector are all free-form surfaces with a surface shape of an XY polynomial. The radius of the primary reflector is -8926 mm, the radius of the secondary four-coplanar reflector of one of the dual-line array cameras is -4363 mm, and the radius of the third reflector of one of the dual-line array cameras is -3072 mm; the radius of the secondary four-coplanar reflector of another dual-line array camera is -4399 mm, and the radius of the third reflector of another dual-line array camera is -3084 mm.

[0014] In the above technical solution, the shapes of the primary reflector, the secondary four-coplanar reflector and the third reflector are all rectangular.

[0015] In the above technical solution, the distance between the aperture stop and the main reflector is 1744 mm; the center-to-center distance between the main reflector and the sub-four-coplanar reflector of each dual-line array camera is 1708 mm; the center-to-center distance between the sub-four-coplanar reflector and the third reflector of one dual-line array camera is 1601 mm, and when the sub-four-coplanar reflector serves as the fourth reflective surface of the dual-line array camera, the center-to-center distance between the sub-four-coplanar reflector and the focal plane is 1750 mm; the center-to-center distance between the sub-four-coplanar reflector and the third reflector of another dual-line array camera is 1588 mm, and when the sub-four-coplanar reflector serves as the fourth reflective surface of the dual-line array camera, the center-to-center distance between the sub-four-coplanar reflector and the focal plane is 1750 mm.

[0016] The beneficial effects of the present invention are:

[0017] The advantages of the common-aperture dual-line array mapping camera optical system based on secondary mirror multiplexing of the present invention are as follows:

[0018] (1) The two off-axis four-mirror optical systems are designed with a common aperture. That is, the aperture stop and the main reflector of the two optical systems (i.e., the dual-line array camera) are the same, realizing an integrated optical system design. They can be installed in the same mechanical structure, making it easy to take effective thermal control measures, making the temperature field inside the camera more uniform and improving the stability of the optical system. When calculating the external and internal orientation elements, the dimensional chain error is reduced, and the surveying and mapping accuracy is improved.

[0019] (2) The common aperture structure and secondary mirror multiplexing structure simplify the optical system of the dual-line array camera, reduce three reflective mirrors, effectively reduce the size of the system, and reduce the cost of launch.

[0020] (3) The reflector of the optical system of the present invention has no tilt or eccentricity, which greatly reduces the difficulty of installation and alignment.

[0021] (4) The secondary mirror of the off-axis four-mirror optical system is coplanar with the four mirrors and most of the optically effective areas overlap, that is, the secondary mirror is reused, which makes the coplanar reflector miniaturized and reduces the volume and mass of the optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Figure 1 Schematic diagram of the structure of the optical system of the common-aperture dual-line array mapping camera based on secondary mirror multiplexing of the present invention.

[0024] Figure 2 This is a modulation transfer function curve of the first dual-line array camera in the common-aperture dual-line array mapping camera optical system based on secondary mirror multiplexing of the present invention.

[0025] Figure 3This is a modulation transfer function curve of the second dual-line array camera in the common-aperture dual-line array mapping camera optical system based on secondary mirror multiplexing of the present invention.

[0026] Figure 4 This is a spot diagram of the first dual-line array camera in the optical system of the dual-line array mapping camera with a common aperture and secondary mirror multiplexing according to the present invention. In the figure, the Airy disk radius is 8.464 μm, with reference to the principal ray. The RMS radii corresponding to fields of view 1 to 12 are 4.997 μm, 4.899 μm, 4.840 μm, 4.899 μm, 3.249 μm, 4.615 μm, 3.270 μm, 4.615 μm, 3.40 3μm, 4.965μm, 5.371μm, 4.965μm; the GEO radii corresponding to fields of view 1 to 12 are 21.172μm, 14.987μm, 11.904μm, 14.987μm, 8.625μm, 13.958μm, 7.572μm, 13.958μm, 8.970μm, 13.456μm, 18.257μm, 13.456μm respectively.

[0027] Figure 5 This is a spot diagram of the second dual-line array camera in the optical system of the secondary mirror multiplexing-based common-aperture dual-line array mapping camera of the present invention. In the figure, the Airy disk radius is 8.463 μm, referring to the principal ray. The RMS radii corresponding to fields of view 1-12 are 5.890 μm, 4.976 μm, 5.120 μm, 4.976 μm, 3.878 μm, 4.574 μm, 3.318 μm, 4.574 μm, and 3.638 μm, respectively. m, 5.368μm, 5.650μm, 5.368μm; the GEO radii corresponding to fields of view 1 to 12 are 23.327μm, 15.531μm, 16.038μm, 15.531μm, 11.113μm, 12.548μm, 8.340μm, 12.548μm, 10.200μm, 14.195μm, 17.278μm, 14.195μm respectively.

[0028] The reference numerals in the figures indicate:

[0029] 1-Aperture stop, 2-Main mirror, 3-Secondary quadruplanar mirror of the first dual-line array camera, 4-Third mirror of the first dual-line array camera, 5-Focal plane of the first dual-line array camera, 6-Secondary quadruplanar mirror of the second dual-line array camera, 7-Third mirror of the second dual-line array camera, 8-Focal plane of the second dual-line array camera, 9-First dual-line array camera, 10-Second dual-line array camera. DETAILED DESCRIPTION

[0030] The inventive concept of the present invention is to address the shortcomings of separate dual-line array mapping cameras, such as large size and mass, and the difficulty in controlling the measurement accuracy between the independent optical components. This invention designs an off-axis four-mirror optical system for a common-aperture dual-line array camera based on secondary mirror reuse. This optical system simultaneously utilizes an integrated structure with a common primary mirror for the dual-line array cameras and a structure in which the secondary mirror and the four mirrors are coplanar and their effective areas largely overlap. The integrated structure of the dual-line array cameras with a common primary mirror employs a common aperture design for the two dual-line array camera optical systems. That is, the primary mirrors of the two off-axis four-mirror optical systems are the same mirror with the same surface expression. This not only eliminates a primary mirror, reducing the difficulty of mirror assembly and inspection costs, but also achieves an integrated optical system design that can be installed within the same mechanical structure, facilitating effective thermal control measures to achieve a relatively uniform internal temperature field and improve the stability of the optical system. This reduces dimensional chain errors when calculating exterior and interior orientation elements, thereby improving mapping accuracy. The sub-quadruple coplanar reflector of the present invention utilizes a structure in which the secondary and four mirrors are coplanar, with overlapping effective areas. Compared to traditional off-axis four-mirror systems for surveying and mapping cameras, this system eliminates one reflector, reducing the difficulty of system adjustment and testing costs. To address the problem of excessive reflector diameter caused by the coplanarity of traditional dual mirrors, the effective areas of the secondary and four mirrors are overlapped over a large area. This effectively reduces the weight and volume of the coplanar reflector compared to previous coplanar off-axis optical systems. To further reduce the volume, the focal plane is placed between the primary and third reflectors, while maintaining the coplanarity of the secondary and four mirrors, allowing for overlapping optical paths and improving space utilization. The optical system of the present invention simultaneously utilizes an integrated structure in which a dual-line array camera shares a common primary mirror, and a structure in which the secondary and four mirrors are coplanar, with their effective areas largely overlapping. This system not only eliminates three reflectors in the integrated dual-line array camera, significantly reducing the difficulty of adjustment and testing costs, but also introduces a free-form surface to achieve coplanarity between the secondary and four mirrors, allowing the two reflection areas of the coplanar reflector to overlap, reducing the volume and mass of the coplanar reflector. By placing the focal plane between the primary reflector and the third reflector, the light rays are overlapped without reducing the image quality, which compresses the volume of the optical system, improves the space utilization of the system, and reduces the cost of launch.

[0031] The present invention will be described in detail below with reference to the accompanying drawings.

[0032] Combine Figure 1 The optical system of the common-aperture dual-line array mapping camera based on secondary mirror multiplexing of the present invention is specifically described, comprising an aperture stop 1, a primary reflector 2, a secondary four-coplanar reflector 3 of a first dual-line array camera, a third reflector 4 of the first dual-line array camera, a focal plane 5 of the first dual-line array camera, a secondary four-coplanar reflector 6 of a second dual-line array camera, a third reflector 7 of the second dual-line array camera, and a focal plane 8 of the second dual-line array camera;

[0033] The aperture stop 1, the main reflector 2, the secondary four-coplanar reflector 3 of the first dual-line array camera, the third reflector 4 of the first dual-line array camera, and the focal plane 5 of the first dual-line array camera constitute a first dual-line array camera 9; the aperture stop 1, the main reflector 2, the secondary four-coplanar reflector 6 of the second dual-line array camera, the third reflector 7 of the second dual-line array camera, and the focal plane 8 of the second dual-line array camera constitute a second dual-line array camera 10; the first dual-line array camera 9 and the second dual-line array camera 10 share the same aperture stop 1 and main reflector 2.

[0034] The main reflector 2 serves as the first reflective surface of the first dual-line array camera 9 and also serves as the first reflective surface of the second dual-line array camera 10;

[0035] The secondary four-coplanar reflector 3 of the first dual-line array camera serves as the second and fourth reflective surfaces of the first dual-line array camera 9 and is coaxially arranged with the main reflector 2. In the reflected light path of the main reflector 1, the optically effective area of ​​the second reflective surface almost covers the upper and lower parts of the secondary four-coplanar reflector 3 of the first dual-line array camera, and the optically effective area of ​​the fourth reflective surface is mainly located in the upper half or lower half of the secondary four-coplanar reflector 3 of the first dual-line array camera. The two optically effective areas partially overlap, thereby reducing the volume and weight of the secondary four-coplanar reflector 3 of the first dual-line array camera, thereby achieving miniaturization and lightweighting of the secondary four-coplanar reflector 3 of the first dual-line array camera. The third reflector 4 of the first dual-line array camera serves as the third reflective surface of the first dual-line array camera 9 and is coaxially arranged with the main reflector 2 and the secondary four-coplanar reflector 3 of the first dual-line array camera, and is in the reflected light path of the secondary four-coplanar reflector 3 of the first dual-line array camera.

[0036] The secondary four-coplanar reflector 6 of the second dual-line array camera serves as the second and fourth reflective surfaces of the second dual-line array camera 10 and is coaxially arranged with the main reflector 2. In the reflected light path of the main reflector 1, the optically effective area of ​​the second reflective surface almost covers the upper and lower parts of the secondary four-coplanar reflector 6 of the second dual-line array camera, and the optically effective area of ​​the fourth reflective surface is mainly located in the upper half or lower half of the secondary four-coplanar reflector 6 of the second dual-line array camera. The two optically effective areas partially overlap, reducing the volume and weight of the secondary four-coplanar reflector 6 of the second dual-line array camera, thereby achieving miniaturization and lightweighting of the secondary four-coplanar reflector 6 of the second dual-line array camera. The third reflector 7 of the second dual-line array camera serves as the third reflective surface of the second dual-line array camera 10 and is coaxially arranged with the main reflector 2 and the secondary four-coplanar reflector 6 of the second dual-line array camera, and is in the reflected light path of the secondary four-coplanar reflector 6 of the second dual-line array camera.

[0037] The secondary four-mirror coplanar reflector 3 of the first dual-line array camera and the secondary four-mirror coplanar reflector 6 of the second dual-line array camera are both obtained by setting the secondary mirror and the four mirrors of the off-axis four-mirror system to coincide with each other in the center position, and have the same surface parameters.

[0038] The present invention's common-aperture dual-line array mapping camera optical system, based on secondary mirror reuse, employs an off-axis field of view. In the first dual-line array camera 9, the central field of view is deflected 11.25° counterclockwise relative to the optical axis, while in the second dual-line array camera 10, the central field of view is deflected 11.25° clockwise relative to the optical axis. By adjusting the off-axis field of view angle and introducing a free-form surface with an XY polynomial shape, the focal plane 5 of the first dual-line array camera is positioned above the primary reflector 2 and below the third reflector 4 of the first dual-line array camera. Similarly, the focal plane 8 of the second dual-line array camera is positioned below the primary reflector 2 and above the third reflector 7 of the second dual-line array camera. This not only reduces system size and improves image quality, but also prevents the system's optical path from being obstructed by the reflectors, avoids the introduction of mirror eccentricity and tilt, and reduces the difficulty and cost of installation and adjustment.

[0039] The reflectors of the optical system of the first dual-line array camera 9 are all free-form surfaces with an XY polynomial shape. The optical system has a wavelength range of 400 nm to 800 nm, a focal length of 7000 mm, an F-number of 11, a rectangular field of view with a full field of view of 6° × 0.5°, a meridional field of view of 11° to 11.5°, and a sagittal field of view of -3° to 3°. The optical system of the first dual-line array camera 9 is an off-axis system, with an off-axis value of 11.25° at the center of the meridional field of view. The image-side diffuse spot of each field of view is close to the Airy disk radius, and the spatial resolution of the full field of view is greater than 0.33 at 72 lp / mm.

[0040] The reflectors of the optical system of the second dual-line scan camera 10 are all free-form surfaces with an XY polynomial shape. The optical system has a wavelength range of 400 nm to 800 nm, a focal length of 7000 mm, an F-number of 11, and a rectangular field of view. The full field of view is 6° × 0.5°, with a meridional field of view range of -11° to -11.5° and a sagittal field of view range of -3° to 3°. The optical system of the second dual-line scan camera 10 is an off-axis system, with an off-axis value of -11.25° at the center of the meridional field of view. The image-side dispersion of each field of view is close to the Airy disk radius, and the spatial resolution of the full field of view is greater than 0.34 at 72 lp / mm.

[0041] The reflectors of the secondary mirror multiplexing-based common-aperture dual-line array mapping camera optical system of the present invention are all rectangular in shape, and all reflective surfaces have no inclination or eccentricity relative to the optical axis.

[0042] The distance between the aperture stop 1 and the primary reflector 2 of the common-aperture dual-line array mapping camera optical system based on secondary mirror multiplexing of the present invention is 1744 mm. The primary reflector 2 is a free-form surface with an XY polynomial surface shape and a radius of -8926 mm. The center distances between the primary reflector 2 and the secondary four-coplanar reflector 3 of the first dual-line array camera and the secondary four-coplanar reflector 6 of the second dual-line array camera are both 1708 mm.

[0043] The sub-quadruple-coplanar reflector 3 of the first dual-line array camera is a free-form surface with an XY polynomial shape and a radius of -4363 mm. The center-to-center distance between the sub-quadruple-coplanar reflector 3 of the first dual-line array camera and the third reflector 4 of the first dual-line array camera is 1601 mm. The third reflector 4 of the first dual-line array camera is a free-form surface with an XY polynomial shape and a radius of -3072 mm. The center-to-center distance between the third reflector 4 of the first dual-line array camera and the sub-quadruple-coplanar reflector 3 of the first dual-line array camera is 1601 mm. When the sub-quadruple-coplanar reflector 3 of the first dual-line array camera serves as the fourth reflector (i.e., the fourth reflective surface) of the first dual-line array camera 9, the center-to-center distance between the sub-quadruple-coplanar reflector 3 of the first dual-line array camera and the focal plane 5 of the first dual-line array camera is 1750 mm.

[0044] The sub-quadruple-coplanar reflector 6 of the second dual-line array camera is a free-form surface with an XY polynomial shape and a radius of -4399 mm. The center-to-center distance between the sub-quadruple-coplanar reflector 6 and the third reflector 7 of the second dual-line array camera is 1588 mm. The third reflector 7 of the second dual-line array camera is a free-form surface with an XY polynomial shape and a radius of -3084 mm. The center-to-center distance between the third reflector 7 and the sub-quadruple-coplanar reflector 6 of the second dual-line array camera is 1588 mm. When the sub-quadruple-coplanar reflector 6 of the second dual-line array camera serves as the fourth reflector (i.e., the fourth reflective surface) of the second dual-line array camera 10, the center-to-center distance between the sub-quadruple-coplanar reflector 6 and the focal plane 8 of the second dual-line array camera is 1750 mm.

[0045] The present invention's common-aperture dual-line array mapping camera optical system, based on secondary mirror multiplexing, has a wavelength range of 400 nm to 800 nm, a focal length of 7000 mm, and an F-number of 11. The optical system is an off-axis system, with the center field of view in the system's meridional direction off-axis of 11.25° and -11.25°, respectively. The meridional fields of view of the two dual-line array cameras are 11° to 11.5° and -11° to -11.5°, respectively. Taking the average values ​​of 11.25° and -11.25°, the included angle between the front and rear viewing axes of the two dual-line array cameras' optical systems is 22.5°. Figure 2 and Figure 3These are the modulation transfer function curves of the optical systems of the first and second dual-line array cameras. The full-field MTF of the system is greater than 0.33 at a spatial resolution of 72lp / mm. Figure 4 and Figure 5 The spot diagrams of the optical systems of the first and second dual-line scan cameras, respectively, show that the image-side diffuse spot radius is close to the Airy disk radius. The three-dimensional dimensions (length × width × height) of the optical system are approximately 1785 mm × 880 mm × 2800 mm.

[0046] The common-aperture dual-line array mapping camera optical system based on secondary mirror multiplexing of the present invention is practical and effective through simulation.

[0047] The working process of the common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing of the present invention is as follows:

[0048] When the common-aperture dual-line array mapping camera optical system based on secondary mirror reuse of the present invention operates on a satellite platform, when the first dual-line array camera 9 is used to image a ground object for the first time, the parallel light emitted by the object sequentially passes through the optical system's aperture stop 1, primary reflector 2, the first dual-line array camera's secondary four-coplanar reflector 3, the first dual-line array camera's third reflector 4, and the first dual-line array camera's secondary four-coplanar reflector 3, ultimately forming an image on the first dual-line array camera's focal plane 5. When the second dual-line array camera 10 is used to image the same ground object for the second time, the parallel light emitted by the object sequentially passes through the optical system's aperture stop 1, primary reflector 2, the second dual-line array camera's secondary four-coplanar reflector 6, the second dual-line array camera's third reflector 7, and the second dual-line array camera's secondary four-coplanar reflector 6, ultimately forming an image on the second dual-line array camera's focal plane 8. The three-dimensional coordinates of the ground object can be calculated using the two imaging results, interior and exterior orientation elements of the two dual-line array cameras.

[0049] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing, characterized in that: include: Two dual-line array cameras sharing the same aperture stop and primary mirror; Each of the dual-line array cameras further comprises: a secondary four-coplanar reflector, a third reflector and a focal plane; The main reflector serves as the first reflective surface of one dual-line array camera and also serves as the first reflective surface of another dual-line array camera; The secondary four-coplanar reflector of each dual-line array camera serves as the second and fourth reflective surfaces of the dual-line array camera and is coaxially arranged with the primary reflector. The optically effective use area of ​​the second reflective surface covers the upper and lower parts of the secondary four-coplanar reflector, and the optically effective use area of ​​the fourth reflective surface is located in the upper half or lower half of the secondary four-coplanar reflector, and the two optically effective use areas partially overlap. The third reflector serves as the third reflective surface of the dual-line array camera and is coaxially arranged with the primary reflector and the secondary four-coplanar reflector, and is on the reflection light path of the secondary four-coplanar reflector. The focal plane is located between the primary reflector and the third reflector.

2. The common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing according to claim 1, characterized in that: The secondary four-coplanar reflector is an off-axis four-mirror system in which the secondary mirror and the four mirrors are arranged to coincide with each other in the center position and have the same surface parameters.

3. The common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing according to claim 1, characterized in that: The field of view is set up in an off-axis manner. In one of the dual-line array cameras, the central field of view is deflected 11.25° counterclockwise relative to the optical axis, and in the other dual-line array camera, the central field of view is deflected 11.25° clockwise relative to the optical axis.

4. The common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing according to claim 1, characterized in that: The field of view of one of the dual-line array cameras is a rectangular field of view, with a full field of view of 6°×0.5°, a field of view range in the meridional direction of 11° to 11.5°, and a field of view range in the sagittal direction of -3° to 3°; the field of view of the other dual-line array camera is a rectangular field of view, with a full field of view of 6°×0.5°, a field of view range in the meridional direction of -11° to -11.5°, and a field of view range in the sagittal direction of -3° to 3°.

5. The common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing according to claim 1, characterized in that: The primary reflector, secondary tetraplanar reflector, and third reflector are all free-form surfaces with a surface shape of an XY polynomial. The radius of the primary reflector is -8926 mm, the radius of the secondary tetraplanar reflector of one of the dual-line array cameras is -4363 mm, and the radius of the third reflector of one of the dual-line array cameras is -3072 mm; the radius of the secondary tetraplanar reflector of another dual-line array camera is -4399 mm, and the radius of the third reflector of another dual-line array camera is -3084 mm.

6. The common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing according to claim 1, characterized in that: The primary reflector, the secondary four-coplanar reflector and the third reflector are all rectangular in shape.

7. The common aperture dual-line array mapping camera optical system based on secondary mirror multiplexing according to claim 1, characterized in that: The distance between the aperture stop and the main reflector is 1744 mm; the center distance between the main reflector and the sub-four-coplanar reflector of each dual-line array camera is 1708 mm; the center distance between the sub-four-coplanar reflector and the third reflector of one dual-line array camera is 1601 mm, and when the sub-four-coplanar reflector serves as the fourth reflective surface of the dual-line array camera, the center distance between the sub-four-coplanar reflector and the focal plane is 1750 mm; the center distance between the sub-four-coplanar reflector and the third reflector of another dual-line array camera is 1588 mm, and when the sub-four-coplanar reflector serves as the fourth reflective surface of the dual-line array camera, the center distance between the sub-four-coplanar reflector and the focal plane is 1750 mm.

Images