Lens image quality testing device in complete machine state

Abstract

The invention relates to a lens image quality testing device in a complete machine state, and belongs to the technical field of spaceflight optical remote sensors. Comprising a camera lens, an image quality testing mirror and an interferometer. The optical axis of the camera lens is axially and horizontally placed; the axial left side of the camera lens is a light inlet, and the axial right side is a light outlet; the camera exit pupil position is located in the camera lens; in a normal state, incident light is focused on a camera focal plane on the right side of the axial direction of a camera lens under the convergence of an exit pupil position of the camera; the image quality testing mirror is arranged in the camera lens and is positioned on the right side of the exit pupil position of the camera; the interferometer is arranged below the camera lens; light passing through the exit pupil position of the camera is refracted and converged on the interferometer through the image quality testing mirror; light detection is realized through the interferometer; the problem that after the focal plane is installed, only system MTF testing can be carried out, and the lens image quality cannot be directly tested is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace optical remote sensors and relates to a lens image quality testing device in an integrated state. Background Art

[0002] The imaging quality of the optical system is an important indicator for evaluating space optical remote sensors (hereinafter referred to as cameras). In the lens state, the imaging quality is usually evaluated by testing the wavefront aberration of the lens with an interferometer. In the whole machine state, the optical transfer function (MTF) is usually tested. Both of these detection methods are considered to be accurate, objective, and quantitative image quality evaluation indicators, which can be used to evaluate the imaging quality of the system.

[0003] It should be noted that after the camera has completed the docking and focusing of the lens and focal plane assembly, the transmission function test method can only detect the imaging quality of the camera system composed of the lens and focal plane assembly, and cannot detect the image quality of the lens alone.

[0004] In engineering practice, it is often the case that after the whole machine has undergone a series of space environment adaptability tests, when the imaging quality is retested, the MTF drops abnormally. The reasons for the decrease in MTF can usually be divided into three categories: lens misalignment, focal plane component misalignment, and overall defocus of the focal plane position. Among them, lens misalignment can be further divided into mirror type misalignment and mirror position misalignment. Focal plane component misalignment can be further divided into detector position misalignment and mirror position misalignment within the focal plane. Due to the limitations of system transmission function detection, in order to troubleshoot problems, it is usually necessary to perform separate simulation analysis or separate tests on each component. This process is time-consuming and labor-intensive and relies more on engineering experience, which is not accurate or direct enough. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and to propose a lens image quality testing device in an integrated state, which solves the problem that after the focal plane is installed, only the system MTF test can be performed and the lens image quality cannot be directly tested.

[0006] The solution of the present invention is:

[0007] A lens image quality testing device in a complete state, comprising a camera lens, an image quality testing mirror, and an interferometer;

[0008] Among them, the optical axis of the camera lens is placed horizontally; the axial left side of the camera lens is the light entrance, and the axial right side is the light exit; the camera exit pupil position is located inside the camera lens; under normal conditions, the incident light is focused on the camera focal plane on the axial right side of the camera lens under the convergence of the camera exit pupil position; the image quality test mirror is arranged inside the camera lens and is located on the right side of the camera exit pupil position; the interferometer is arranged below the camera lens; the light passing through the camera exit pupil position is refracted and converged on the interferometer through the image quality test mirror; the image quality detection of the camera lens is realized through the interferometer.

[0009] In the above-mentioned lens image quality testing device in a complete state, the focal plane of the camera is transferred to the interferometer through the image quality testing mirror.

[0010] In the above-mentioned lens image quality test device in a complete state, the mirror type value of the image quality test mirror is better than λ is the wavelength of incident light.

[0011] In the above-mentioned lens image quality test device in a complete state, the test device also includes n image quality test lens target balls, n interferometer target balls, n camera lens target balls and a laser tracker;

[0012] The laser tracker is axially and horizontally arranged at the light outlet position of the camera lens; n image quality test mirror target balls are arranged on the image quality test mirror; n interferometer target balls are arranged on the interferometer; and n camera lens target balls are arranged on the camera lens.

[0013] In the above-mentioned lens image quality testing device in a complete machine state, n is a positive integer not less than 3; the n image quality testing mirror target balls on the image quality testing mirror are dispersedly arranged to envelop the image quality testing mirror; the n interferometer target balls on the interferometer are dispersedly arranged to envelop the interferometer; the n camera lens target balls of the camera lens are dispersedly arranged to envelop the camera lens.

[0014] In the above-mentioned lens image quality testing device in a complete state, the field of view of the laser tracker can observe the image quality testing mirror target ball, the interferometer target ball and the camera lens target ball, so as to determine the relative position relationship between the image quality testing mirror, the camera lens and the interferometer.

[0015] In the above-mentioned lens image quality testing device in a complete state, the points for testing the lens image quality include 0 field of view point, ±0.5 field of view point, ±0.7 field of view point and ±1 field of view point.

[0016] In the above-mentioned lens image quality testing device in a complete state, each field of view point is located in the field of view direction after refraction by the image quality testing mirror; that is, the interferometer is moved to the 0 field of view point, ±0.5 field of view point, ±0.7 field of view point and ±1 field of view point in the field of view direction to perform image quality testing on the camera lens.

[0017] In the above-mentioned lens image quality testing device in a complete state, the 0 field of view point is a point at the center position in the field of view direction.

[0018] In the above-mentioned complete state, the lens image quality test device measures the relative positions of the interferometer target ball and the image quality test lens target ball through a laser tracker, so as to move the interferometer to the 0 field of view point, ±0.5 field of view point, ±0.7 field of view point and ±1 field of view point in the field of view direction respectively.

[0019] The beneficial effects of the present invention compared with the prior art are:

[0020] (1) The present invention is applied to the lens image quality test in the whole machine state, which solves the problem that after the focal plane is installed, only the system MTF test can be performed, but the lens image quality cannot be directly tested. By using the test mirror installed at the appropriate position of the camera system, the system optical path is led out to the outside of the camera, and the led-out optical path is quantitatively tested, so that the influence of the focal plane component on the system MTF can be removed and the lens image quality can be directly determined;

[0021] (2) The present invention sets a tracker target ball on the image quality test mirror and the interferometer, and tests the specified field of view of the lens by accurately controlling the measurement points, so that the test data before and after can be accurately compared, and the digital twin model of the lens can be improved according to the test results;

[0022] (3) The lens imaging quality evaluation method provided by the present invention, which does not rely on the system MTF test, can be used to accurately test the lens when it is difficult to completely unload the large-aperture camera on the ground and the ground transfer function test results are difficult to characterize the on-orbit imaging quality scene. The digital twin technology can be used to accurately estimate the on-orbit image quality of the lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the lens image quality testing device of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the embodiments.

[0025] The present invention provides a lens image quality testing device in a complete state, which refracts light passing through the camera exit pupil position and converges it on an interferometer through an image quality testing mirror; the interferometer is used to detect light; the present invention solves the problem that after the focal plane is installed, only the system MTF test can be performed, and the lens image quality cannot be directly tested.

[0026] The lens image quality test device in the whole machine state, such as Figure 1As shown, it specifically includes a camera lens 1, an image quality test mirror 4, and an interferometer 5. Among them, the optical axis of the camera lens 1 is placed horizontally; the axial left side of the camera lens 1 is the light inlet, and the axial right side is the light outlet; the camera exit pupil position 3 is located inside the camera lens 1; under normal conditions, the incident light is focused on the camera focal plane 2 on the axial right side of the camera lens 1 under the convergence of the camera exit pupil position 3; the image quality test mirror 4 is arranged inside the camera lens 1 and is located on the right side of the camera exit pupil position 3; the interferometer 5 is arranged below the camera lens 1; the light passing through the camera exit pupil position 3 is refracted and converged on the interferometer 5 through the image quality test mirror 4; and the image quality detection of the camera lens 1 is realized through the interferometer 5.

[0027] The camera focal plane 2 is transferred to the interferometer 5 by the image quality test mirror 4. The mirror type value of the image quality test mirror 4 is better than λ is the wavelength of incident light.

[0028] In order to increase the test points, the test device also includes n image quality test mirror target balls 6, n interferometer target balls 7, n camera lens target balls 8 and a laser tracker 9. The laser tracker 9 is axially and horizontally arranged at the light outlet position of the camera lens 1; the n image quality test mirror target balls 6 are arranged on the image quality test mirror 4; the n interferometer target balls 7 are arranged on the interferometer 5; and the n camera lens target balls 8 are arranged on the camera lens 1.

[0029] Among them, n is a positive integer not less than 3; the n image quality test mirror target balls 6 on the image quality test mirror 4 are dispersedly arranged to envelop the image quality test mirror 4; the n interferometer target balls 7 on the interferometer 5 are dispersedly arranged to envelop the interferometer 5; the n camera lens target balls 8 of the camera lens 1 are dispersedly arranged to envelop the camera lens 1.

[0030] The field of view of the laser tracker 9 enables observation of the image quality test mirror target sphere 6, the interferometer target sphere 7 and the camera lens target sphere 8, so as to determine the relative positional relationship among the image quality test mirror 4, the camera lens 1 and the interferometer 5.

[0031] The design of the test points is:

[0032] The points for testing the image quality of the lens include the 0 field of view point, ±0.5 field of view point, ±0.7 field of view point and ±1 field of view point. Each field of view point is located in the field of view direction after refraction by the image quality test mirror 4; that is, the interferometer 5 is moved to the 0 field of view point, ±0.5 field of view point, ±0.7 field of view point and ±1 field of view point in the field of view direction to perform image quality testing of the camera lens 1. Among them, the 0 field of view point is the point at the center position in the field of view direction.

[0033] By measuring the relative positions of the interferometer target sphere 7 and the image quality test mirror target sphere 6 by the laser tracker 9, the interferometer 5 is moved to the 0 field of view point, ±0.5 field of view point, ±0.7 field of view point and ±1 field of view point in the field of view direction respectively.

[0034] The image quality test mirror of the present invention includes a test mirror and an image quality test mirror frame. The test mirror is a plane mirror, arranged behind the lens exit pupil, and used to bend the lens optical path out. In order to ensure the accuracy of the test, there are certain requirements for the image quality test mirror surface shape. It is usually required to install the image quality test mirror frame and properly fix the rear shape to reach 1 / 60λ (λ=632.8nm). The arrangement position of the image quality test mirror requires that the entire system optical path can be folded to a position suitable for interferometer testing;

[0035] The measuring point positioning system includes a laser tracker target ball and a laser tracker, which are used to accurately locate the measuring point. The laser tracker target ball is properly installed on the image quality test mirror system and the interferometer through the target ball mount. The target ball mount can be magnetic or other tracker recommended forms. The laser tracker is used to measure the position of each target ball, which can reflect the spatial position of the image quality test mirror relative to the camera coordinate system and the relative position of the image quality test mirror and the interferometer.

[0036] The interferometer is arranged at the focal plane of the light path led out from the image quality test mirror and is used to test the wavefront aberration of the lens.

[0037] The present invention is applied to the lens image quality test in the whole machine state, and solves the problem that after the focal plane is installed, only the system MTF test can be performed, and the lens image quality cannot be directly tested. By using the test mirror installed at the appropriate position of the camera system, the system light path is led out to the outside of the camera, and the led-out light path is quantitatively tested, so that the influence of the focal plane component on the system MTF can be removed and the lens image quality can be directly determined.

[0038] The present invention arranges a tracker target ball on the image quality test mirror and the interferometer, and tests the specified field of view of the lens by precisely controlling the measuring points, so that the test data before and after can be accurately compared, and the digital twin model of the lens can be improved according to the test results.

[0039] The lens imaging quality evaluation method provided by the present invention, which does not rely on the system MTF test, can be used to accurately test the lens when it is difficult to completely unload a large-aperture camera on the ground and the ground transfer function test results are difficult to characterize the on-orbit imaging quality scenario, and accurately estimate the on-orbit image quality of the lens through digital twin technology.

[0040] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A lens image quality testing device in a complete state, characterized in that: It comprises a camera lens (1), an image quality test mirror (4), and an interferometer (5); The optical axis of the camera lens (1) is placed horizontally; the left side of the camera lens (1) is a light inlet, and the right side of the camera lens (1) is a light outlet; the camera exit pupil position (3) is located inside the camera lens (1); under normal conditions, incident light is focused on a camera focal plane (2) on the right side of the camera lens (1) under the convergence of the camera exit pupil position (3); an image quality test mirror (4) is arranged inside the camera lens (1) and on the right side of the camera exit pupil position (3); an interferometer (5) is arranged below the camera lens (1); light passing through the camera exit pupil position (3) is refracted and converged on the interferometer (5) by the image quality test mirror (4); and image quality detection of the camera lens (1) is achieved by the interferometer (5).

2. The lens image quality testing device in the complete state according to claim 1, characterized in that: The camera focal plane (2) is transferred to the interferometer (5) through an image quality testing mirror (4).

3. The lens image quality testing device in the complete state according to claim 1, characterized in that: The mirror type value of the image quality test mirror (4) is better than λ is the wavelength of incident light.

4. The lens image quality testing device in the complete state according to claim 1, characterized in that: The testing device also includes n image quality testing mirror target balls (6), n interferometer target balls (7), n camera lens target balls (8) and a laser tracker (9); The laser tracker (9) is axially and horizontally arranged at the light outlet position of the camera lens (1); n image quality test mirror target balls (6) are arranged on the image quality test mirror (4); n interferometer target balls (7) are arranged on the interferometer (5); and n camera lens target balls (8) are arranged on the camera lens (1).

5. The lens image quality testing device in the complete state according to claim 4, characterized in that: The n is a positive integer not less than 3; the n image quality test mirror target balls (6) on the image quality test mirror (4) are dispersedly arranged to envelop the image quality test mirror (4); the n interferometer target balls (7) on the interferometer (5) are dispersedly arranged to envelop the interferometer (5); and the n camera lens target balls (8) of the camera lens (1) are dispersedly arranged to envelop the camera lens (1).

6. The lens image quality testing device in the complete state according to claim 5, characterized in that: The field of view of the laser tracker (9) enables observation of the image quality test mirror target ball (6), the interferometer target ball (7) and the camera lens target ball (8), thereby determining the relative positional relationship among the image quality test mirror (4), the camera lens (1) and the interferometer (5).

7. The lens image quality testing device in the complete state according to claim 6, characterized in that: The points for testing the image quality of the lens include the 0 field of view point, ±0.5 field of view point, ±0.7 field of view point and ±1 field of view point.

8. The lens image quality testing device in the complete state according to claim 7, characterized in that: Each field of view point is located in the field of view direction after refraction by the image quality test mirror (4); that is, the interferometer (5) is moved to the 0 field of view point, ±0.5 field of view point, ±0.7 field of view point and ±1 field of view point in the field of view direction to perform image quality testing of the camera lens (1).

9. The lens image quality testing device in the complete state according to claim 8, characterized in that: The 0 field of view point is a point at the center position in the field of view direction.

10. The lens image quality testing device in the complete state according to claim 8, characterized in that: By measuring the relative positions of the interferometer target ball (7) and the image quality test mirror target ball (6) using a laser tracker (9), the interferometer (5) is moved to the 0 field of view point position, the ±0.5 field of view point position, the ±0.7 field of view point position and the ±1 field of view point position in the field of view direction.

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