An inner baffle of coaxial off-axis field optical system and its design method

Abstract

The application discloses an inner baffle of a coaxial partial field optical system and a design method thereof, and solves the technical problems that the existing inner baffle cannot shield or absorb stray light generated by the reflection of light entering a primary mirror and the primary mirror, especially stray light generated near the edge of a secondary mirror or the edge of a secondary mirror support, and that the stray light directly enters a receiving reflection area of the primary mirror, thereby seriously affecting the detection result formed by receiving the light, and that a least square method is used for three-dimensional profile fitting, and the fitting process is complex. The inner baffle of the coaxial partial field optical system comprises an inner baffle body arranged between the primary mirror and the secondary mirror, wherein the inner baffle body comprises an inner baffle interface, a plurality of light blocking rings and a connecting piece, the plurality of light blocking rings are arranged in parallel and sequentially arranged along the optical axis direction, two adjacent light blocking rings are axially connected through the connecting piece, the connecting part of the two is located in the corresponding end face of the light blocking ring, one end of the inner baffle interface is connected with one of the plurality of light blocking rings close to the primary mirror, and the other end is connected with the primary mirror.

Description

Technical Field

[0001] This invention relates to optical systems, and more specifically to an inner light shield for a coaxial polarized field-of-view optical system and its design method. Background Technology

[0002] In the coaxial polarized field-reflection system optical camera used in spacecraft, the central ray of the target beam enters the camera barrel with an skewed optical axis not equal to 0°. It is reflected by the primary mirror to the secondary mirror, and then by the secondary mirror into the optical rear assembly within the central aperture of the primary mirror. During the primary and secondary reflections, the target ray alternates between the primary and secondary mirrors. Under the influence of internal and external interference sources such as sunlight, uncertain heat sources, and imperfect conditions during processing, coating, and blackening, non-target rays and stray internal light deviating from the main path enter the light-transmitting area from various angles, forming internal and external stray light. Ultimately, this affects the detection results formed by receiving the light.

[0003] Typically, a solid object is placed in the non-light-transmitting area of ​​the target ray between the primary and secondary mirrors. A light-blocking ring structure is made on the surface of the solid object to prevent stray light from easily getting trapped, thus fully absorbing and removing spatial stray light passing through these areas and retaining the light entering the field of view. Especially in the case of field-biased reflection, it is particularly necessary to set up an inner light shield between the primary and secondary mirrors to separate the incident target ray from stray light.

[0004] Existing technologies typically utilize ray tracing in optical design software to determine the total length of the inner light shield based on the intersecting positions of the rays. By combining the convergence shapes of the light rays at different positions after reflection from the primary and secondary mirrors, the light-blocking ring structures at different positions are determined, and the interface of the inner light shield is also determined, ultimately determining its optical effects and mechanical properties.

[0005] Chinese invention patent (CN116893544A) discloses a lens hood for a polarized field-of-view optical system and its manufacturing method, which solves the technical problem that traditional lens hoods cannot achieve good stray light suppression for polarized field-of-view optical systems. The lens hood for a polarized field-of-view optical system includes a lens hood body; the contour of the lens hood body is generated by three-dimensional contour fitting of the light transmission range boundaries on the longitudinal sections of multiple imaging beams located between the primary and secondary mirrors; multiple circumferential grooves are formed along the axial direction on the inner wall of the lens hood body, and protrusions on both sides of the circumferential grooves form corresponding multiple light-blocking rings of equal width; the inner and outer surfaces of the lens hood body and the surface of the light-blocking rings are all blackened to ensure that the transmittance of visible light point sources and the transmittance of infrared point sources meet the requirements of the imaging optical path.

[0006] The aforementioned technical solution primarily addresses the shielding of stray light from the secondary mirror reflecting into the central beam of the primary mirror. Therefore, its outer surface is a smooth structure, only considering the top edge's light-blocking effect. Only an internal light-blocking ring exists; light passing through the inner and outer edges of the light-blocking cover is not processed. The light-blocking ring only serves to prevent stray light from the secondary mirror's reflected light. Reflected light entering the primary mirror and the primary mirror itself, especially stray light near the secondary mirror's shielding edge or generated on the secondary mirror's support, is not blocked or absorbed and directly enters the primary mirror's receiving reflection area, severely affecting the detection results formed by receiving light. Furthermore, its three-dimensional contour fitting uses the least squares method in 3D modeling software, making the fitting process complex. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problems of existing internal light shields, which prevent reflected light entering the primary mirror and the primary mirror, especially stray light near the edge of the secondary mirror or generated on the secondary mirror support, from being blocked or absorbed and directly entering the primary mirror receiving reflection area, thus seriously affecting the detection results formed by receiving light. In addition, the invention addresses the technical problems of the complexity of the three-dimensional contour fitting process using the least squares method in three-dimensional modeling software. The invention provides an internal light shield for a coaxial off-field optical system and its design method.

[0008] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0009] An inner light shield for a coaxial polarized field-of-view optical system, the coaxial polarized field-of-view optical system including a primary mirror, a secondary mirror and an optical rear group located inside the lens barrel, the primary mirror having a central polarization aperture, and the optical rear group located within the central polarization aperture; its special feature is that it includes an inner light shield body disposed between the primary mirror and the secondary mirror.

[0010] One end of the inner light shield body is connected to the primary mirror, and the other end is set directly opposite the secondary mirror. It is used to allow the target light of the polarized field of view to enter the lens tube, be reflected by the primary mirror to the secondary mirror to form a first effective beam, and then be reflected by the secondary mirror into the optical rear group in the central polarized hole of the primary mirror to form a second effective beam.

[0011] The inner light shield body includes an inner light shield interface, multiple light-blocking rings and connectors. The multiple light-blocking rings are arranged in parallel and sequentially along the optical axis. Adjacent light-blocking rings are connected by connectors, and the connection part of the two rings is located in the end face of the corresponding light-blocking ring. One end of the inner light shield interface is connected to one of the multiple light-blocking rings that is closest to the main mirror, and the other end is connected to the main mirror.

[0012] Each light-blocking ring is generated based on the edge coordinate values ​​of the sequence of light spots corresponding to the first spot projection of the first effective beam and the second spot projection of the second effective beam. The central hole of the first spot projection of the first effective beam constrains the outer contour of the light-blocking ring, while the inner contour of the light-blocking ring is generated using the edge coordinate values ​​of the sequence of light spots corresponding to the second spot projection of the second effective beam. The first spot projection and the second spot projection are respectively the projections of the first effective beam and the second effective beam on the radial plane where the corresponding light-blocking ring is located.

[0013] Furthermore, the inner light shield body is prepared by three-dimensional printing.

[0014] Furthermore, both the inner and outer surfaces of the inner sunshade are coated with black matte paint.

[0015] Meanwhile, the present invention also provides a design method for an inner light shield of a coaxial polarized field-of-view optical system, which is characterized by including the following steps:

[0016] Step 1: Using ray tracing in optical design software, determine the total length of the inner light shield body along the optical axis based on the intersecting positions of the target rays in the biased field of view.

[0017] Step 2: In the optical design software, construct the reflecting surfaces of the primary mirror and the secondary mirror, and the optical rear group located in the central offset aperture of the primary mirror. The target light of the polarized field of view is incident on the reflecting surface of the primary mirror, and then reflected to the reflecting surface of the secondary mirror to form the first effective beam; then reflected by the reflecting surface of the secondary mirror into the optical rear group in the central offset aperture of the primary mirror to form the second effective beam, thus obtaining the spatial distribution of the effective beam.

[0018] Step 3: Based on the spatial distribution of the effective beams, determine the maximum outer contour of the inner light shield body by the inner side of the spatial envelope surface formed by the first effective beams, and determine the minimum inner contour of the inner light shield body by the outer side of the spatial envelope surface formed by the second effective beams, thus obtaining the three-dimensional spatial design range of the inner light shield body.

[0019] Step 4: Within the three-dimensional spatial design range of the inner light shield body, the total length of the inner light shield body is divided into N interval points along the axis. At each interval point, the edge coordinate values ​​of the sequence spots corresponding to the first spot projection of the first effective beam and the second spot projection of the second effective beam are used to generate the corresponding light blocking ring. Adjacent light blocking rings are axially connected through connectors. The connection part of the two is located in the end face corresponding to the light blocking ring, forming the light blocking part of the inner light shield body.

[0020] Step 5: Based on the structure of the primary mirror to be connected, generate an inner light shield interface at one end of a light-blocking ring near the primary mirror, thereby obtaining the inner light shield body and completing the design of the inner light shield for the coaxial polarized field-of-view optical system.

[0021] Furthermore, step 4 specifically includes the following steps:

[0022] Step 4.1 In the optical design software, within the three-dimensional spatial design range of the inner light shield body, the total length of the inner light shield body is divided into N interval points along the axis. Based on the main cross section of the three-dimensional spatial design range of the inner light shield body, the boundary limit feature points on the main cross section are determined to obtain the boundary region within the main cross section.

[0023] Step 4.2: Based on the N interval points of the inner light shield body, within the boundary region of the main cross-section, determine N radial sections corresponding one-to-one with the N interval points, serving as the physical positions of the N light-blocking rings. On each radial section, obtain the first spot projection of the first effective beam and the second spot projection of the second effective beam. The first spot projection is used to limit the outer contour of the light-blocking ring corresponding to each radial section, and the second spot projection is used to limit the inner contour of the light-blocking ring corresponding to each radial section. ;

[0024] Step 4.3: The second spot projection on each radial section is formed by the overlapping of multiple sequences of spots with different fields of view. Based on the edge coordinates of each sequence of spots, M extreme positions are determined on each radial section, and each extreme position corresponds to a sequence of spots. ;

[0025] Step 4.4: Import the first spot projection on each radial section obtained in Step 4.2 and the M sequence spots on each radial section obtained in Step 4.3 into the mechanical design software. The first spot projection on each radial section forms the outer contour of the light-blocking ring corresponding to that radial section.

[0026] Step 4.5: Connect two adjacent light spots in the M light spots on each radial section, and make the connecting line tangent to the two light spots respectively to form the inner contour of the light-blocking ring corresponding to each radial section, thus obtaining N light-blocking rings;

[0027] Step 4.6: Select a connection area on the corresponding end face of each light-blocking ring, generate a connector within the three-dimensional space design range of the inner light-shielding body, and connect two adjacent light-blocking rings axially. After N light-blocking rings are connected, the inner light-shielding body is obtained.

[0028] Furthermore, in step 4.1, the number of boundary limit feature points is six.

[0029] Furthermore, in step 4.1, N=17; in step 4.3, M=8.

[0030] Furthermore, the following steps are included between step 4.5 and step 4.6:

[0031] The outer contour of the light-blocking ring obtained in step 4.4 is contracted inward by L; the inner contour of the light-blocking ring obtained in step 4.5 is expanded outward by L, wherein, .

[0032] Furthermore, in step 4.5, the N light-blocking rings are distributed at equal intervals along the optical axis.

[0033] Furthermore, in step 4.5, the thickness of each of the N light-blocking rings is the same, which is h. .

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] 1. The present invention provides an inner light shield for a coaxial polarized field-of-view optical system. By setting multiple light-blocking rings and placing the connector inside the end face of the light-blocking rings, the inner and outer surfaces of the inner light shield body form a multi-layer light-blocking ring structure, which can block stray light entering the light transmission area and absorb stray light deviating from the light transmission area, cut off the relevant stray light path, and effectively suppress internal and external stray light.

[0036] 2. The present invention provides an inner light shield for a coaxial polarized field-of-view optical system. By applying black matte paint to both the inner and outer surfaces of the inner light shield body, stray light can be suppressed to the greatest extent while preventing the generation of new stray light sources.

[0037] 3. This invention discloses a design method for an inner light shield of a coaxial polarized field-of-view optical system. The inner light shield is designed as a multi-layered light-blocking ring, which not only absorbs stray light entering the non-transmitting area but also effectively suppresses internal and external stray light. After generating a first effective beam and a second effective beam using target light in optical design software, the spatial distribution of the effective beams is obtained. Between the spatial distributions of the first and second effective beams, the three-dimensional spatial design range of the inner light shield body is obtained. The inner light shield is lightweighted by filling a solid within the three-dimensional spatial design range of the inner light shield body. The inner light shield body is not directly generated but is divided into multiple layers. Light-blocking rings are generated in each layer using the first and second effective beams. Then, connectors are generated to axially connect the N light-blocking rings. The design method is simple and efficient, and the light-blocking effect is good.

[0038] 4. The present invention provides a design method for an inner light shield of a coaxial polarized field-of-view optical system. Taking into account factors such as the total length of the inner light shield body, processing characteristics, interlayer installation operability, and distance from the interlayer connection point to the edge of the light-blocking ring, the number of light-blocking rings is set to N=17, which can achieve the optimal practicality of the light-blocking effect.

[0039] 5. The present invention provides a design method for an inner light shield of a coaxial biased field-of-view optical system. Based on the ray tracing results of optical design software, the inner contour of the inner light shield body can be constructed by controlling a small number of boundary limit feature points. This is a practical and effective technical approach.

[0040] 6. The present invention provides a design method for an inner light shield of a coaxial off-field optical system. The second light spot projection is formed by the overlapping of multiple sequences of light spots with different fields of view. Considering that the region where the second light spot is formed takes the extreme positions of the maximum envelope on the four boundaries of the upper, lower, left, and right, the upper and lower boundaries each have 4 extreme positions, and the left and right side boundaries have the same 2 extreme positions as the upper and lower boundaries, that is, the sequences of light spots corresponding to M=8 extreme positions are connected by the maximum outer shape envelope. A simple geometric method is used to form the inner contour of the light shielding ring corresponding to each radial section, without the need for formula and parameter calculation, which is simple and convenient.

[0041] 7. The present invention provides a design method for an inner light shield of a coaxial polarized field-of-view optical system. Considering the dimensional errors and light-blocking effects of 3D printing, the method involves shrinking the outer contour of the light-blocking ring inward by a value of L, and expanding the inner contour of the light-blocking ring outward by a value of L. This allows the light-blocking ring to avoid the "spatial light-transmitting area," thus improving the effect of the light-blocking ring in blocking stray light. Attached Figure Description

[0042] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment of the inner light shield of a coaxial polarized field-of-view optical system according to the present invention;

[0043] Figure 2 This is a schematic diagram of the structure of an embodiment of the inner light shield of the coaxial polarized field-of-view optical system of the present invention, installed in the coaxial polarized field-of-view optical system;

[0044] Figure 3 This is a schematic diagram of the first light spot projection on a certain radial section in step 4.2 of an embodiment of the design method of the inner light shield of a coaxial polarized field-of-view optical system of the present invention.

[0045] Figure 4 In step 4.2 of the embodiment of the design method of the inner light shield of the coaxial polarized field-of-view optical system of the present invention, the design method is related to... Figure 3 A schematic diagram of the projection of the second light spot on the same radial section (containing multiple sequential light spots);

[0046] Figure 5 This is a partial enlarged view of the main cross section of the three-dimensional design range of the inner light shield body in step 4.1 of the embodiment of the design method of the inner light shield of the coaxial polarized field optical system of the present invention. Point E is the upper part of the mirror, point F is the lower part of the mirror, point G is the upper part of the far main mirror, point H is the upper part of the near main mirror, point I is the lower part of the near main mirror, and point J is the lower part of the far main mirror.

[0047] Figure 6 This is a schematic diagram illustrating the generation of the inner and outer contours of the light-blocking ring in steps 4.4 and 4.5 of an embodiment of the design method for the inner light shield of a coaxial polarized field-of-view optical system of the present invention. 9 represents the position before the outer contour of the light-blocking ring contracts inward, and 9 represents the position after the outer contour of the light-blocking ring contracts inward. The position before the inner contour of the light-blocking ring expands outward is shown in Figure 10. The position after the inner contour of the light-blocking ring expands outward is shown in Figure 10. A, B, C, and D are the numbers of the four sequential light spots. , , , , There are five connecting lines. and connecting wires The first line is the line connecting the sequence of light spots and the axis of symmetry of the light-blocking ring; the other three lines are lines connecting adjacent sequence of light spots.

[0048] Figure 7 This is an axial sectional view of an embodiment of the inner light shield of a coaxial polarized field-of-view optical system according to the present invention;

[0049] Figure 8 for Figure 7 Partial sectional views, where (a) is the sectional view at AA, (b) is the sectional view at BB, and (c) is the sectional view at CC;

[0050] Figure 9 This is a schematic diagram of N interval points in step 4 of an embodiment of the design method of the inner light shield of a coaxial polarized field-of-view optical system of the present invention.

[0051] Figure 10 This is a schematic diagram of the mechanical performance simulation results of an embodiment of the inner light shield of a coaxial polarized field-of-view optical system of the present invention. The length scale bar of the diagram is shown below.

[0052] Figure 11 This is a schematic diagram illustrating the mechanical performance simulation results of an embodiment of the inner light shield of a coaxial polarized field-of-view optical system according to the present invention.

[0053] Figure 12 This is a point source transmittance (PST) curve used in an embodiment of the design method of the inner light shield of a coaxial off-field optical system of the present invention to evaluate the stray light suppression effect using stray light analysis software.

[0054] The annotations in the attached figures are explained as follows:

[0055] 1. Inner light shield body; 2. Inner light shield interface; 3. Light blocking ring; 4. Connector; 5. Fixing screw; 6. Lens barrel; 7. Primary lens; 8. Secondary lens. Detailed Implementation

[0056] To make the objectives, advantages, and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0057] like Figure 1-12 As shown, this embodiment provides an inner light shield for a coaxial polarized field-of-view optical system. The coaxial polarized field-of-view optical system includes a primary mirror 7, a secondary mirror 8, and a rear optical group located within a lens barrel 6. The primary mirror 7 is provided with a central polarization aperture, and the rear optical group is located within the central polarization aperture. The inner light shield of the coaxial polarized field-of-view optical system includes an inner light shield body 1 disposed between the primary mirror 7 and the secondary mirror 8.

[0058] One end of the inner light shield body 1 is connected to the primary mirror 7, and the other end is set directly opposite the secondary mirror 8. It is used to allow the target light of the polarized field of view to enter the lens tube 6, be reflected by the primary mirror 7 to the secondary mirror 8 to form the first effective beam, and then be reflected by the secondary mirror 8 into the optical rear group in the central polarized hole of the primary mirror 7 to form the second effective beam.

[0059] The inner light shield body 1 includes an inner light shield interface 2, multiple light-blocking rings 3, and a connector 4. The multiple light-blocking rings 3 are arranged in parallel and sequentially along the optical axis. Adjacent light-blocking rings 3 are connected by the connector 4, and the connection part is located in the corresponding end face of the light-blocking ring 3. One end of the inner light shield interface 2 is connected to one of the multiple light-blocking rings 3 closest to the main mirror 7, and the other end is connected to the main mirror 7. In this embodiment, the inner light shield interface 2 is provided with a fixing screw 5 for connecting to the main mirror 7.

[0060] Each light-blocking ring 3 is generated based on the edge coordinate values ​​of the sequence of light spots corresponding to the first spot projection of the first effective beam and the second spot projection of the second effective beam. The central hole of the first spot projection of the first effective beam constrains the outer contour of the light-blocking ring 3, while the inner contour of the light-blocking ring 3 is generated using the edge coordinate values ​​of the sequence of light spots corresponding to the second spot projection of the second effective beam. The first spot projection and the second spot projection are respectively the projections of the first effective beam and the second effective beam on the radial plane where the corresponding light-blocking ring 3 is located.

[0061] The inner light shield body 1 is prepared by three-dimensional printing, and both the inner and outer surfaces of the inner light shield body 1 are coated with black matte paint.

[0062] Meanwhile, the present invention also provides a design method for an inner light shield of a coaxial polarized field-of-view optical system, comprising the following steps:

[0063] Step 1: Using the ray tracing function of optical design software, determine the total length of the inner light shield body 1 along the optical axis based on the position of the intersecting target rays in the biased field of view.

[0064] Step 2: In the optical design software, construct the reflecting surfaces of the primary mirror 7 and the secondary mirror 8, and the optical rear group located within the central offset aperture of the primary mirror 7. Inject the polarized target light rays into the reflecting surface of the primary mirror 7, then reflect them to the reflecting surface of the secondary mirror 8, forming the first effective beam. The light rays are then reflected by the reflecting surface of the secondary mirror 8 into the optical rear group within the central offset aperture of the primary mirror 7, forming the second effective beam. This yields the spatial distribution of the effective beams, as shown below. Figure 2 As shown;

[0065] Step 3: Based on the spatial distribution of the effective beams, the maximum outer contour of the inner light shield body 1 is determined by the inner side of the spatial envelope surface formed by the first effective beams, and the minimum inner contour of the inner light shield body 1 is determined by the outer side of the spatial envelope surface formed by the second effective beams, thus obtaining the three-dimensional spatial design range of the inner light shield body 1.

[0066] Step 4: Within the three-dimensional spatial design range of the inner light shield body 1, divide the total length of the inner light shield body 1 into N interval points along the axial direction. At each interval point, as shown... Figure 3-4 As shown, the edge coordinate values ​​of the sequence spots corresponding to the first spot projection of the first effective beam and the second spot projection of the second effective beam are used to generate the corresponding light-blocking rings 3. Adjacent light-blocking rings 3 are axially connected by connectors 4, and the connection part of the two is located in the end face corresponding to the light-blocking rings 3 to form the light-blocking part of the inner light-blocking cover body 1. The specific steps are as follows:

[0067] Step 4.1, as follows Figure 9 As shown, in the optical design software, within the three-dimensional spatial design range of the inner light shield body 1, the total length of the inner light shield body 1 is divided into N interval points along the axial direction. For example... Figure 5 As shown, based on the main cross section of the three-dimensional spatial design range of the inner light shield body 1, the boundary limit feature points on the main cross section are determined to obtain the boundary region within the main cross section; the main cross section is the axial cross section of the three-dimensional spatial design range of the inner light shield body 1. In this embodiment, the number of boundary limit feature points is six. The six boundary limit feature points are: point E is the upper part of the mirror, point F is the lower part of the mirror, point G is the upper part of the far main mirror, point H is the upper part of the near main mirror, point I is the lower part of the near main mirror, and point J is the lower part of the far main mirror.

[0068] Figure 9 and Figure 7 The front sectional view is used in conjunction to show the position and shape of the intervals on the filled entity, as well as the height of each radial section relative to the reference plane, with the radial section of the light-blocking ring closest to the inner light-shielding interface 2 being the reference plane.

[0069] Step 4.2, as follows Figure 7-9As shown, based on the N interval points of the inner light shield body 1, N radial sections corresponding one-to-one with the N interval points are determined within the boundary region of the main section, serving as the physical positions of the N light-blocking rings. On each radial section, a first spot projection of the first effective beam and a second spot projection of the second effective beam are obtained. The first spot projection is used to limit the outer contour of the light-blocking ring 3 corresponding to each radial section, and the second spot projection is used to limit the inner contour of the light-blocking ring 3 corresponding to each radial section. The upper limit of N is constrained by the spacing between the light-blocking rings 3 and the total length of the inner light-shielding body 1; in this embodiment, N=17.

[0070] Step 4.3: The second spot projection on each radial section is formed by the overlapping of multiple sequences of spots with different fields of view. Based on the edge coordinates of each sequence of spots, M extreme positions are determined on each radial section, and each extreme position corresponds to a sequence of spots, such as... Figure 4 As shown, where In this embodiment, M=8, that is, there are 4 upper boundaries and 4 lower boundaries, and the left and right side boundaries are the same as the two extreme positions of the upper and lower boundaries.

[0071] Step 4.4: Import the first spot projection on each radial section obtained in Step 4.2 and the M sequence spots on each radial section obtained in Step 4.3 into the mechanical design software. The first spot projection on each radial section forms the outer contour of the light-blocking ring 3 corresponding to that radial section.

[0072] Step 4.5: Connect two adjacent light spots from the M light spots on each radial section, with the connecting line tangent to each of the two light spots, to form the inner contour of the corresponding light-blocking ring 3 on each radial section, resulting in N light-blocking rings 3; For example... Figure 6 As shown, a, b, c, and d are the numbers of the four sequence spots. , , , , There are five connecting lines. and connecting wires The first line is the line connecting the sequence of light spots and the axis of symmetry of the light-blocking ring. The other three lines are the lines connecting adjacent sequence of light spots. This figure only shows a schematic diagram of the connection of sequence of light spots on one side. Since the shapes of the light spots are all symmetrical about the left and right, their symmetrical sides can be obtained by direct mirroring.

[0073] In this embodiment, N light-blocking rings 3 are distributed at non-equidistant intervals along the optical axis, and the thickness of the N light-blocking rings 3 is the same, which is h. It can also be set with equal intervals and non-uniform thickness. The h value must ensure both the overall rigidity of the inner light shield body 1 (since 3D printing uses non-metallic materials with low elastic modulus, meaning they are relatively soft and require a certain thickness to prevent warping and deformation) and the light-blocking effect (because if the light-blocking ring is too thick, there will be more stray light reflected from the edges). Theoretically, the thinner the better; therefore, the thinnest thickness is the one required to meet the rigidity requirements. For example... Figure 8 As shown, the radial cross-sectional shape of the light-blocking ring 3 at different intervals varies with the shape of the light spot, resulting in two closed contours up to one closed contour.

[0074] Step 4.6: Shrink the outer contour of the light-blocking ring 3 obtained in step 4.4 inward by L; expand the inner contour of the light-blocking ring 3 obtained in step 4.5 outward by L, wherein, Considering manufacturing and installation errors, the light-blocking ring 3 may not be able to completely block this area. Therefore, the outer contour of the light-blocking ring 3 needs to be reduced inward by L, and the inner contour needs to be expanded outward by L, to avoid interfering with useful light rays. Figure 6 As shown, 9 represents the position before the outer contour of the light-blocking ring contracts inward, and 9 represents the position after the outer contour of the light-blocking ring contracts inward. The position before the inner contour of the light-blocking ring expands outward is 10, and the position after the inner contour of the light-blocking ring expands outward is 10.

[0075] Step 4.7: Select a connection area within the end face of each light-blocking ring 3, and generate a connector 4 within the three-dimensional spatial design range of the inner light-shielding body 1. Connect adjacent light-blocking rings 3 axially. After connecting N light-blocking rings 3, the inner light-shielding body 1 is obtained. The connection position between adjacent layers should be as far away from the edge of the light-blocking ring 3 as possible while ensuring the overall rigidity of the inner light-shielding body 1. That is, the connection area should be located as close as possible to the middle of the end face of the light-blocking ring 3. Within the light-blocking ring at the top of the inner light-shielding body 1, the edge of the corresponding connector should be more than 1 mm away from the edge of the light-blocking ring 3.

[0076] Step 5: Based on the structure of the position to be connected to the primary mirror 7, generate an inner light shield interface 2 at one end of a light-blocking ring 3 near the primary mirror 7 to obtain the inner light shield body 1, thus completing the design of the inner light shield of the coaxial polarized field optical system.

[0077] Based on the inner light shield of the generated coaxial polarized field-of-view optical system (hereinafter referred to as the inner light shield), the position of the bottom inner light shield interface 2 is fixed, and a 20g radial overload deformation simulation is performed. The maximum deformation is 6mm, and the deformation ratio relative to the total length is less than 1.7%. Figure 10 As shown.

[0078] Subsequently, a stress analysis was performed under 20g radial acceleration, and the maximum internal stress was found to be 14.3 MPa. Less than The material's yield strength is 65 MPa. For example... Figure 11 As shown.

[0079] Using stray light analysis software and a surface scattering model of the optical elements in the inner light shield, the scattering characteristics of each surface in the infrared band were simulated using the Harvey-Shack model combined with roughness. Both the inner and outer surfaces of the inner light shield were treated with black matte paint. Based on the point source transmittance (PST) comparison, the light-shielding effect of the inner light shield provided by this invention is superior to that of traditional light shields. Simulation curves are shown below. Figure 12 As shown.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present invention.

Claims

1. An inner light shield for a coaxial polarized field-of-view optical system, the coaxial polarized field-of-view optical system comprising a primary mirror (7), a secondary mirror (8), and a rear optical group located within a lens barrel (6), wherein the primary mirror (7) is provided with a central polarization aperture, and the rear optical group is located within the central polarization aperture; characterized in that: Includes an inner light shield body (1) disposed between the primary mirror (7) and the secondary mirror (8); One end of the inner light shield body (1) is connected to the main mirror (7), and the other end is set directly opposite the secondary mirror (8). It is used to allow the target light of the polarized field of view to enter the lens tube (6), be reflected by the main mirror (7) to the secondary mirror (8) to form a first effective beam, and then be reflected by the secondary mirror (8) into the optical rear group in the central polarized hole of the main mirror (7) to form a second effective beam. The inner light shield body (1) includes an inner light shield interface (2), multiple light-blocking rings (3) and a connector (4). The multiple light-blocking rings (3) are arranged in parallel and sequentially along the optical axis. Adjacent light-blocking rings (3) are connected by the connector (4). The connection part of the two is located in the end face of the corresponding light-blocking ring (3). One end of the inner light shield interface (2) is connected to one of the multiple light-blocking rings (3) that is closer to the main mirror (7), and the other end is connected to the main mirror (7). Each light-blocking ring (3) is generated based on the edge coordinate values ​​of the sequence of light spots corresponding to the first spot projection of the first effective beam and the second spot projection of the second effective beam. The central hole of the first spot projection of the first effective beam constrains the outer contour of the light-blocking ring (3), while the inner contour of the light-blocking ring (3) is generated using the edge coordinate values ​​of the sequence of light spots corresponding to the second spot projection of the second effective beam. The first spot projection and the second spot projection are the projections of the first effective beam and the second effective beam on the radial plane where the corresponding light-blocking ring (3) is located, respectively.

2. The inner light shield of the coaxial polarized field-of-view optical system according to claim 1, characterized in that: The inner light shield body (1) is prepared by three-dimensional printing.

3. The inner light shield of the coaxial polarized field-of-view optical system according to claim 1, characterized in that: The inner and outer surfaces of the inner light shield body (1) shown are coated with black matte paint.

4. A method for designing an inner light shield for a coaxial polarized field-of-view optical system according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Using the ray tracing function of optical design software, determine the total length of the inner light shield body (1) along the optical axis based on the position of the intersecting target rays in the biased field of view. Step 2: In the optical design software, construct the reflecting surfaces of the primary mirror (7) and the secondary mirror (8) and the optical rear group located in the central offset aperture of the primary mirror (7). The target light of the polarized field of view is incident on the reflecting surface of the primary mirror (7) and then reflected to the reflecting surface of the secondary mirror (8) to form the first effective beam. Then, it is reflected by the reflecting surface of the secondary mirror (8) into the optical rear group in the central offset aperture of the primary mirror (7) to form the second effective beam, thus obtaining the spatial distribution of the effective beam. Step 3: Based on the spatial distribution of the effective beams, determine the maximum outer contour of the inner light shield body (1) by the inner side of the spatial envelope surface formed by the first effective beams, and determine the minimum inner contour of the inner light shield body (1) by the outer side of the spatial envelope surface formed by the second effective beams, so as to obtain the three-dimensional spatial design range of the inner light shield body (1). Step 4: Within the three-dimensional space design range of the inner light shield body (1), the total length of the inner light shield body (1) is divided into N interval points along the axis. At each interval point, the edge coordinate values ​​of the sequence spots corresponding to the first spot projection of the first effective beam and the second spot projection of the second effective beam are used to generate the corresponding light blocking ring (3). The two adjacent light blocking rings (3) are axially connected through the connector (4). The connection part of the two is located in the end face corresponding to the light blocking ring (3) to form the light blocking part of the inner light shield body (1). Step 5: Based on the structure of the position to be connected to the main mirror (7), generate an inner light shield interface (2) at one end of a light-blocking ring (3) near the main mirror (7), thereby obtaining the inner light shield body (1) and completing the design of the inner light shield of the coaxial polarized field optical system.

5. The design method of the inner light shield of the coaxial polarized field-of-view optical system according to claim 4, characterized in that, Step 4 specifically includes the following steps: Step 4.1 In the optical design software, within the three-dimensional space design range of the inner light shield body (1), the total length of the inner light shield body (1) is divided into N interval points along the axis. Based on the main section of the three-dimensional space design range of the inner light shield body (1), the boundary limit feature points on the main section are determined, and the boundary region within the main section is obtained. Step 4.2: Based on the N interval points of the inner light shield body (1), determine N radial sections corresponding to the N interval points within the boundary region of the main section, as the physical positions of the N light-blocking rings. Obtain the first spot projection of the first effective beam and the second spot projection of the second effective beam on each radial section. The first spot projection is used to limit the outer contour of the light-blocking ring (3) corresponding to each radial section, and the second spot projection is used to limit the inner contour of the light-blocking ring (3) corresponding to each radial section. ; Step 4.3: The second spot projection on each radial section is formed by the overlapping of multiple sequences of spots with different fields of view. Based on the edge coordinates of each sequence of spots, M extreme positions are determined on each radial section, and each extreme position corresponds to a sequence of spots. ; Step 4.4: Import the first spot projection on each radial section obtained in Step 4.2 and the M sequence spots on each radial section obtained in Step 4.3 into the mechanical design software. The first spot projection on each radial section forms the outer contour of the light-blocking ring (3) corresponding to that radial section. Step 4.5: Connect two adjacent sequence spots in the M sequence spots on each radial section, and make the connecting line tangent to the two sequence spots respectively to form the inner contour of the corresponding light-blocking ring (3) of each radial section, and obtain N light-blocking rings (3). Step 4.6: Select the connection area in the corresponding end face of each light-blocking ring (3), generate the connector (4) within the three-dimensional space design range of the inner light shield body (1), and connect the two adjacent light-blocking rings (3) axially. After the N light-blocking rings (3) are connected, the inner light shield body (1) is obtained.

6. The design method of the inner light shield of the coaxial polarized field-of-view optical system according to claim 5, characterized in that: In step 4.1, the number of boundary limit feature points is six.

7. The design method of the inner light shield of the coaxial polarized field-of-view optical system according to claim 5, characterized in that: In step 4.1, N=17; in step 4.3, M=8.

8. The design method of the inner light shield of the coaxial polarized field-of-view optical system according to claim 5, characterized in that, The following steps are also included between steps 4.5 and 4.6: The outer contour of the light-blocking ring (3) obtained in step 4.4 is contracted inward by L; the inner contour of the light-blocking ring (3) obtained in step 4.5 is expanded outward by L, wherein, .

9. The design method of the inner light shield of the coaxial polarized field-of-view optical system according to claim 5, characterized in that: In step 4.5, N light-blocking rings (3) are distributed at equal intervals along the optical axis.

10. The design method of the inner light shield of the coaxial polarized field-of-view optical system according to claim 5, characterized in that: In step 4.5, the thickness of each of the N light-blocking rings (3) is the same, which is h. .

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