A dynamic aberration compensation method for a spliced conformal light window based on a deformable mirror

Abstract

The application discloses a kind of based on deformable mirror's spliced conformal light window dynamic aberration compensation method, optical path difference calculation;According to the pitch angle and azimuth angle of rotation, the incidence angle of incident light on different light window surfaces is calculated;Then, the optical path of light through different light window surfaces is calculated based on the law of refraction, and the optical path difference Δ D Between different light window surfaces is calculated.Light area calculation;According to the pitch angle and azimuth angle of rotation, the corresponding light area of each light window surface on the entrance pupil of the imaging system is calculated by projection relationship.Deformable mirror adjustment;According to the optical path difference between different light window surfaces and the corresponding light area on the entrance pupil, the mirror height of each sub-aperture of the deformable mirror is adjusted, so that the optical path difference between each light area after the reflection of the light by the deformable mirror is 0.The application realizes dynamic compensation of aberration and has good practicability.

Description

Technical Field

[0001] This invention belongs to the technical field of conformal optics, specifically relating to a dynamic aberration compensation method for a stitched conformal optical window based on deformable mirrors. Background Technology

[0002] When an imaging system rotates and scans around a fixed axis within a mosaic conformal optical window, incident light rays may pass through multiple window surfaces simultaneously. The different incident angles of the light rays passing through different window surfaces will produce optical path differences, thereby introducing dynamic aberrations. This will cause the point spread function of the imaging system to split or decrease, and the modulation transfer function to degrade, severely affecting the image quality. Summary of the Invention

[0003] The purpose of this invention is to provide a dynamic aberration compensation method for a stitched conformal window based on deformable mirrors, which aims to solve the above-mentioned problems.

[0004] This invention is mainly achieved through the following technical solutions: A dynamic aberration compensation method based on a deformable mirror and a stitched conformal window includes the following steps: Step S1: Calculate the optical path difference; Based on the pitch and azimuth angles of the rotation, calculate the incident angles of the incident light rays on different optical window surfaces; then, based on the law of refraction, calculate the optical path length of the light rays through different optical window surfaces, and thus calculate the optical path difference Δ between the different optical window surfaces. D ; Step S2: Calculation of the light transmission area; Based on the pitch and azimuth angles of the rotation, calculate the corresponding light transmission area of ​​each light window surface on the entrance pupil of the imaging system through the projection relationship; Step S3: Adjustment of deformable mirror; Based on the optical path difference between different light window surfaces and the corresponding light transmission area on the entrance pupil, adjust the mirror sagitta of each sub-aperture of the deformable mirror so that the optical path difference between each light transmission area after the light is reflected by the deformable mirror is 0, thereby achieving dynamic compensation of aberrations.

[0005] To better realize the present invention, further, in step S1, the optical path difference Δ between different light window surfaces is... D for: in: α 1 and α 2 represents the angle of incidence of light on two adjacent light window surfaces; α Let be the angle of incidence of the incident ray on the surface of the light window, and α for α 1 or α 2; n The refractive index of the optical window; d For thickness; n c Let be the unit normal vector of the entrance pupil plane of the rotating imaging system; R β This is the pitch and rotation matrix; R γ This is the orientation rotation matrix; m The unit normal vector of the light window surface; N Let be the unit normal vector of the entrance pupil plane of the imaging system before rotation.

[0006] To better realize the present invention, the pitch rotation matrix is ​​further... R β and orientation rotation matrix R γ They are respectively: in: β The pitch angle of the imaging system rotation; γ This is the azimuth angle of the imaging system rotation.

[0007] To better realize the present invention, further, in step S2, the intersection line between different light window surfaces is calculated, and then, according to the projection relationship, the projection line of the intersection line on the entrance pupil surface of the imaging system is obtained as the dividing line of the light transmission area corresponding to the two light window surfaces on the entrance pupil surface, so as to determine the light transmission area corresponding to the two light window surfaces.

[0008] To better realize the present invention, further, in step S2, let the unit normal vectors of the two light window surfaces be respectively N 1 and N 2. The intersection line of the two light window surfaces r for: in: p 0 represents any point on the intersection line; n d is the unit direction vector of the intersection line; x The parameter, x∈R, is used to represent the equation of the line; According to projection relationships, the projection line of the intersection line onto the entrance pupil plane of the imaging system is a straight line. s for: in: p 1 represents any point on the entrance pupil plane; n c Let be the unit normal vector of the entrance pupil plane of the rotating imaging system.

[0009] To better realize the present invention, further, in step S3, the mirror sagitta difference between the corresponding light-transmitting areas of the two light-window surfaces on the deformable mirror is adjusted to Δ. D / 2 allows the optical path difference between each light-transmitting area to be 0 after the light is reflected by the deformable mirror, thereby achieving dynamic compensation of aberrations.

[0010] To better realize the present invention, further, for the case where the incident light passes through three optical window surfaces at the same time, one of the optical window surfaces is selected as the reference surface, and the optical path difference between the reference surface and the other two optical window surfaces and the corresponding light transmission area are calculated respectively. Then, the corresponding mirror sagitta is set in each light transmission area to realize aberration compensation.

[0011] The beneficial effects of this invention are as follows: This invention calculates the optical path difference and corresponding light transmission area generated by incident light passing through different optical window surfaces, and then adjusts the deformable mirror to compensate for the optical path difference, achieving dynamic aberration compensation and demonstrating good practicality. This invention can be applied to conformal optical systems requiring large field-of-view scanning, such as airborne optoelectronic detection systems, missile seekers, and lidar. Attached Figure Description

[0012] Figure 1 This is a flowchart of the dynamic aberration compensation method for a stitched conformal window based on deformable mirrors according to the present invention. Figure 2 This is a schematic diagram showing incident light entering the entrance pupil of the imaging system from two surfaces. Figure 3 This is a schematic diagram of the light-transmitting area and optical path difference distribution in Example 2; Figure 4 This is a schematic diagram illustrating the influence of aberrations on the point spread function and modulation transfer function of the imaging system in Example 2. Figure 5 This is a schematic diagram of the aberration compensation effect in Example 2; Figure 6 This is a schematic diagram of the incident light entering the entrance pupil of the imaging system from three surfaces in Example 3; Figure 7 This is a schematic diagram of the light-transmitting area and optical path difference distribution in Example 3; Figure 8 This is a schematic diagram illustrating the influence of aberrations on the point spread function and modulation transfer function of the imaging system in Example 3; Figure 9 This is a schematic diagram of the aberration compensation effect in Example 3. Detailed Implementation Example

[0013] A dynamic aberration compensation method based on deformable mirrors and conformal windows, such as... Figure 1 As shown, it includes: Step S1, Calculation of optical path difference: Calculate the incident angle of the incident light on different optical window surfaces based on the pitch angle and azimuth angle of the rotation, then calculate the optical path of the light through different optical window surfaces using the law of refraction, and then calculate the optical path difference between different optical window surfaces. Step S2, Light transmission area calculation: Based on the pitch and azimuth angles of the rotation, calculate the corresponding light transmission area of ​​each light window surface on the entrance pupil of the imaging system through the projection relationship; Step S3, Deformable Mirror Adjustment: Based on the optical path difference between different light window surfaces and the corresponding light transmission area on the entrance pupil, adjust the mirror sagitta of each sub-aperture of the deformable mirror so that the optical path difference between each light transmission area after the light is reflected by the deformable mirror is 0, thereby achieving dynamic compensation of aberrations.

[0014] Preferably, when the incident light rays pass through the surfaces of two optical windows simultaneously, the pitch angle of the imaging system is set to... β azimuth angle is γ The unit normal vector of the entrance pupil plane of the imaging system before rotation is The unit normal vector of the light window surface is m The angle of incidence of the incident ray on the surface of the optical window can be calculated as follows:

[0015] In the formula: For pitch and rotation matrices, This is the orientation rotation matrix.

[0016] The angle of incidence of light on the two light window surfaces can be calculated using the above formula. and Let the refractive index of the optical window be... Thickness is According to the law of refraction, the optical path difference between the two surfaces is:

[0017] Choose a location, and let the unit normal vectors of the two light window surfaces be respectively and The line of intersection of the two light window surfaces is: ;

[0018] In the formula: Let be any point on the intersection line. is the unit direction vector of the intersection line.

[0019] According to the projection relationship, the projection line of the intersection line onto the entrance pupil plane of the imaging system can be expressed as:

[0020] In the formula: Let be any point on the plane of the entrance pupil.

[0021] The projection of the intersection line onto the entrance pupil plane of the imaging system is the boundary line between the corresponding light-transmitting areas of the two optical window surfaces on the entrance pupil plane, thus determining the corresponding light-transmitting areas of the two optical window surfaces. On a deformable mirror, the difference in mirror sagitta between the corresponding light-transmitting areas of the two optical window surfaces is adjusted to Δ. D / 2 allows the optical path difference between each light-transmitting area to be 0 after the light is reflected by the deformable mirror, thereby achieving dynamic compensation of aberrations.

[0022] Similarly, when incident light passes through three optical window surfaces simultaneously, one surface can be selected as a reference. The optical path difference between the surface and the other two surfaces, as well as the corresponding light transmission area, can be calculated using the formula above. Then, the corresponding mirror sagitta can be set within each light transmission area to achieve aberration compensation. Example

[0023] A dynamic aberration compensation method based on deformable mirrors and conformal windows, such as... Figure 2 and Figure 3 As shown, based on the pitch and azimuth angles of the imaging system rotation and the projection relationship, the optical path difference between the two light window surfaces and the corresponding light-transmitting area can be calculated.

[0024] like Figure 4 As shown, the incident light enters the imaging system after passing through the optical window. Analyzing the point spread function and modulation transfer function of the system's imaging, it can be seen that the aberrations introduced by the optical window will cause the point spread function to split or decrease and the modulation transfer function to decrease, which will seriously affect the imaging quality.

[0025] like Figure 5 As shown, by adjusting the mirror sag of each sub-aperture of the deformable mirror, the optical path difference between the light-transmitting regions after reflection by the deformable mirror is made zero, thus achieving aberration compensation. At this point, analyzing the point spread function and modulation transfer function of the system's imaging reveals that the point spread function and modulation transfer function are significantly improved after compensation using the deformable mirror, indicating that the optical path difference is compensated and the imaging quality is significantly enhanced. Example

[0026] A dynamic aberration compensation method based on deformable mirrors and conformal windows, such as... Figure 6 and Figure 7 As shown, based on the pitch and azimuth angles of the imaging system rotation and the projection relationship, the optical path difference between the three light window surfaces and the corresponding light transmission area can be calculated.

[0027] like Figure 8 As shown, the incident light enters the imaging system after passing through the optical window. Analyzing the point spread function and modulation transfer function of the system's imaging, it can be seen that the aberrations introduced by the optical window will cause the point spread function to split or decrease and the modulation transfer function to decrease, which will seriously affect the imaging quality.

[0028] like Figure 9 As shown, by adjusting the mirror sag of each sub-aperture of the deformable mirror, the optical path difference between the light-transmitting regions after reflection by the deformable mirror is made zero, thus achieving aberration compensation. At this point, analyzing the point spread function and modulation transfer function of the system's imaging reveals that the point spread function and modulation transfer function are significantly improved after compensation using the deformable mirror, indicating that the optical path difference is compensated and the imaging quality is significantly enhanced.

[0029] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A dynamic aberration compensation method for a stitched conformal window based on deformable mirrors, characterized in that, Includes the following steps: Step S1: Calculate the optical path difference; Calculate the incident angle of the incident light on different optical window surfaces based on the pitch and azimuth angles of the rotation. Then, based on the law of refraction, the optical path length of light rays passing through different optical window surfaces is calculated, and the optical path difference Δ between different optical window surfaces is then calculated. D ; Step S2: Calculation of the light transmission area; Based on the pitch and azimuth angles of the rotation, calculate the corresponding light transmission area of ​​each light window surface on the entrance pupil of the imaging system through the projection relationship; Step S3: Adjustment of deformable mirror; Based on the optical path difference between different light window surfaces and the corresponding light transmission area on the entrance pupil, adjust the mirror sagitta of each sub-aperture of the deformable mirror so that the optical path difference between each light transmission area after the light is reflected by the deformable mirror is 0, thereby achieving dynamic compensation of aberrations.

2. The dynamic aberration compensation method for a stitched conformal window based on a deformable mirror according to claim 1, characterized in that, In step S1, the optical path difference Δ between different light window surfaces D for: , , ,in: α 1 and α 2 represents the angle of incidence of light on two adjacent light window surfaces; α Let be the angle of incidence of the incident ray on the surface of the light window, and α for α 1 or α 2; n The refractive index of the optical window; d For thickness; n c Let be the unit normal vector of the entrance pupil plane of the rotating imaging system; R β This is the pitch and rotation matrix; R γ This is the orientation rotation matrix; m The unit normal vector of the light window surface; N Let be the unit normal vector of the entrance pupil plane of the imaging system before rotation.

3. The dynamic aberration compensation method for a stitched conformal window based on a deformable mirror according to claim 2, characterized in that, The pitch rotation matrix R β and orientation rotation matrix R γ They are respectively: , in: β The pitch angle of the imaging system rotation; γ This is the azimuth angle of the imaging system rotation.

4. The dynamic aberration compensation method for a stitched conformal window based on a deformable mirror according to claim 1, characterized in that, In step S2, the intersection line between different light window surfaces is calculated. Then, according to the projection relationship, the projection line of the intersection line on the entrance pupil surface of the imaging system is obtained as the dividing line of the light transmission area corresponding to the two light window surfaces on the entrance pupil surface, so as to determine the light transmission area corresponding to the two light window surfaces.

5. The dynamic aberration compensation method for a stitched conformal window based on a deformable mirror according to claim 4, characterized in that, In step S2, let the unit normal vectors of the two light window surfaces be respectively N 1 and N 2. The intersection line of the two light window surfaces r for: , in: p 0 represents any point on the intersection line; n d is the unit direction vector of the intersection line; x The parameter, x∈R, is used to represent the equation of the line; According to projection relationships, the projection line of the intersection line onto the entrance pupil plane of the imaging system is a straight line. s for: , in: p 1 represents any point on the entrance pupil plane; n c Let be the unit normal vector of the entrance pupil plane of the rotating imaging system.

6. A dynamic aberration compensation method for a stitched conformal window based on a deformable mirror according to any one of claims 1-5, characterized in that, In step S3, the mirror sagitta difference between the corresponding light-transmitting areas of the two light-window surfaces on the deformable mirror is adjusted to Δ. D / 2 allows the optical path difference between each light-transmitting area to be 0 after the light is reflected by the deformable mirror, thereby achieving dynamic compensation of aberrations.

7. The dynamic aberration compensation method for a stitched conformal window based on a deformable mirror according to claim 1, characterized in that, For cases where incident light passes through three optical window surfaces simultaneously, one of the optical window surfaces is selected as the reference surface. The optical path difference between the reference surface and the other two optical window surfaces, as well as the corresponding light transmission areas, are calculated. Then, the corresponding mirror sagitta is set in each of the light transmission areas to achieve aberration compensation.

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