Large aperture annular mirror multi-parameter common reference sub-aperture detection method

Abstract

This invention relates to the field of ring mirror inspection, and more particularly to a multi-parameter common-reference sub-aperture inspection method for large-aperture ring mirrors, comprising contour inspection and surface shape inspection. Contour inspection includes: planning the sub-aperture of the large-aperture ring mirror; rotating the large-aperture ring mirror according to the planned sub-aperture path; turning on the light source, and the emitted detection beam, after being deflected by a grating, is incident on the test point of the large-aperture ring mirror; the detection beam, carrying surface information of the large-aperture ring mirror, is reflected by the test point, converged by a converging lens, and split by a microlens array before being received by an imaging module; the imaging module calculates the slope of the test point of the large-aperture ring mirror to obtain its contour information. Surface shape inspection includes: removing the microlens array from the optical path, and calculating the interference fringes of the test point of the large-aperture ring mirror using the imaging module to obtain its surface shape information. This invention requires only one set of equipment, eliminates equipment switching, avoids assembly and adjustment errors, and saves time and effort.

Description

Technical Field

[0001] This invention relates to the field of ring mirror testing technology, and in particular to a method for detecting the aperture of a large-aperture ring mirror using multiple parameters and a common reference aperture. Background Technology

[0002] Traditional inspection of large-aperture ring mirrors is divided into contour inspection and surface shape inspection. Contour inspection requires the use of a laser contour measuring instrument, while surface shape inspection requires the use of a sub-aperture interferometry device. As can be seen, the existing technology uses two sets of equipment to inspect the contour and surface shape of large-aperture ring mirrors. Each time inspection is carried out, the equipment needs to be switched to achieve the corresponding inspection. Each time the equipment is switched, it needs to be reassembled and adjusted, which not only has the problem of assembly and adjustment errors, but is also time-consuming and labor-intensive. Summary of the Invention

[0003] In view of the above problems, this invention proposes a multi-parameter common reference aperture detection method for large-aperture ring mirrors. It uses a single detection device that can simultaneously perform wavelength-level surface shape detection and millimeter-level contour detection without the need for device switching, without any assembly or adjustment errors, and saves time and effort.

[0004] The present invention provides a method for detecting the multi-parameter common reference sub-aperture of a large-aperture ring mirror, which is implemented using a detection device, including a light source, a grating, a converging lens, a microlens array, and an imaging module.

[0005] The light source is positioned on the optical axis of the large-aperture circular mirror to emit a detection beam;

[0006] A grating is placed on one side of the light source to adjust the direction of the detection beam;

[0007] The converging lens is positioned in the reflection direction of the large-aperture ring mirror to converge the detection beam reflected by the large-aperture ring mirror.

[0008] The microlens array is positioned along the transmission direction of the converging lens to split the detection beam into multiple sub-detection beams;

[0009] The imaging module is used to receive multiple detection beams to detect the surface shape and contour of a large-aperture ring mirror;

[0010] This detection method includes contour detection and surface shape detection; among which,

[0011] Contour detection includes the following steps:

[0012] Step 1: Design sub-apertures for the large-aperture ring mirror;

[0013] Step 2: Rotate the large-aperture annular mirror according to the planned sub-aperture path;

[0014] Step 3: Turn on the light source. The emitted detection beam is refracted by the grating and then incident on the test point of the large-aperture ring mirror.

[0015] Step 4: The detection beam carrying information about the surface of the large-aperture ring mirror, reflected by the point to be measured, is focused by the converging lens and split by the microlens array before being received by the imaging module.

[0016] Step 5: Calculate the slope of the test point of the large-aperture ring mirror using the imaging module to obtain the contour information of the large-aperture ring mirror;

[0017] Surface shape detection includes the following steps:

[0018] Step 1: Design sub-apertures for the large-aperture ring mirror;

[0019] Step 2: Rotate the large-aperture annular mirror according to the planned sub-aperture path;

[0020] Step 3: Remove the microlens array from the optical path, and the detection beam emitted by the light source is refracted by the grating and then incident on the test point of the large-aperture ring mirror.

[0021] Step 4: The detection beam carrying information about the surface of the large-aperture ring mirror, reflected by the test point, is focused by the converging lens and received by the imaging module;

[0022] Step 5: Calculate the interference fringes at the test point of the large-aperture ring mirror using the imaging module to obtain the surface shape information of the large-aperture ring mirror.

[0023] Preferably, the process of calculating the slope of the test point of the large-aperture ring mirror using the imaging module is as follows:

[0024] Let the highest fitting order be N, and express the wavefront Φ(x,y) as a discrete Fourier series, as shown below:

[0025]

[0026] Where n and m are integers, and x and y are discrete spatial coordinates. For the coefficients of the discrete Fourier series, transforming equation (1) yields equation (2):

[0027]

[0028] Applying gradient operators to both sides of equation (2) establishes... The relationship with the slope S(x,y) is shown in equation (3):

[0029]

[0030] Differentiate both sides of formula (3) to obtain the slope of the point to be measured.

[0031] Preferably, the formula for calculating the interference fringes at the test point of the large-aperture ring mirror using the imaging module is:

[0032]

[0033] Where I is the interference fringe intensity, k is the wavenumber, θ is the angular spectrum, D is the beam aperture, B is the beam spacing, and δ is the optical path difference.

[0034] Compared with existing technologies, the present invention uses a single detection device that can simultaneously perform wavelength-level surface detection and millimeter-level contour detection without the need for device switching, eliminates assembly and adjustment errors, and saves time and effort. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the detection device provided according to an embodiment of the present invention.

[0036] Figure labels: 1. Detection beam; 2. Measured point; 3. Converging lens; 4. Microlens array; 5. Imaging module; 6. Large-aperture ring mirror. Detailed Implementation

[0037] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0039] The method for detecting the multi-parameter common reference sub-aperture of a large-aperture ring mirror provided in this invention is based on a detection device, such as... Figure 1 As shown, the detection device includes a light source, a grating, a converging lens 3, a microlens array 4, and an imaging module 5. The light source (not shown) is positioned on the optical axis of the large-aperture ring mirror 6 to emit a detection beam 1. The grating (not shown) is positioned on one side of the light source to adjust the direction of the detection beam 1 so that it is incident on the test point of the large-aperture ring mirror 6. The converging lens 3 is positioned in the reflection direction of the large-aperture ring mirror 6 to converge the detection beam 1 reflected by the large-aperture ring mirror 6. The microlens array 4 is positioned in the transmission direction of the converging lens 3 to split the detection beam 1 into multiple sub-detection beams. The imaging module 5 is used to receive the multiple sub-detection beams and detect the surface shape and contour of the large-aperture ring mirror.

[0040] The large-aperture ring mirror is one of the three mirrors in a three-reflector optical system. The large-aperture ring mirror has a hollow structure and a convex ring surface.

[0041] The large-aperture ring mirror multi-parameter common reference aperture detection method provided in this embodiment of the invention includes contour detection and surface shape detection. The two detections are not sequential. When performing contour detection, the microlens array is placed in the optical path. When performing surface shape detection, the microlens array is removed from the optical path.

[0042] Contour detection includes the following steps:

[0043] Step 1: Design sub-apertures for the large-aperture ring mirror;

[0044] Step 2: Rotate the large-aperture annular mirror according to the planned sub-aperture path;

[0045] Step 3: Turn on the light source. The emitted detection beam is refracted by the grating and then incident on the test point of the large-aperture ring mirror.

[0046] Step 4: The detection beam carrying information about the surface of the large-aperture ring mirror, reflected by the point to be measured, is focused by the converging lens and split by the microlens array before being received by the imaging module.

[0047] Step 5: Calculate the slope of the test point of the large-aperture ring mirror using the imaging module to obtain the contour information of the large-aperture ring mirror.

[0048] The process of calculating the slope of the test point of the large-aperture ring mirror using the imaging module is as follows:

[0049] Let the highest fitting order be N, and express the wavefront Φ(x,y) as a discrete Fourier series, as shown below:

[0050]

[0051] Where n and m are integers, and x and y are discrete spatial coordinates. For the coefficients of the discrete Fourier series, transforming equation (1) yields equation (2):

[0052]

[0053] Applying gradient operators to both sides of equation (2) establishes... The relationship with the slope S(x,y) is shown in equation (3):

[0054]

[0055] Differentiate both sides of formula (3) to obtain the slope of the point to be measured.

[0056] After the large-aperture ring mirror rotates once according to the planned sub-aperture path, the overall outline of the large-aperture ring mirror is obtained.

[0057] Surface shape detection includes the following steps:

[0058] Step 1: Design sub-apertures for the large-aperture ring mirror;

[0059] Step 2: Rotate the large-aperture annular mirror according to the planned sub-aperture path;

[0060] Step 3: Turn on the light source. The emitted detection beam is refracted by the grating and then incident on the test point of the large-aperture ring mirror.

[0061] Step 4: The detection beam carrying information about the surface of the large-aperture ring mirror, reflected by the test point, is focused by the converging lens and received by the imaging module;

[0062] Step 5: Calculate the interference fringes at the test point of the large-aperture ring mirror using the imaging module to obtain the surface shape information of the large-aperture ring mirror.

[0063] The formula for calculating the interference fringes at the test point of a large-aperture ring mirror using the imaging module is as follows:

[0064]

[0065] Where I is the interference fringe intensity, k is the wavenumber, θ is the angular spectrum, D is the beam aperture, B is the beam spacing, and δ is the optical path difference.

[0066] Since the heights of the various test points are different, there is an optical path difference between the detection beams. The local surface shape of the large-aperture ring mirror can be obtained by imaging observation of the interference fringes. After the large-aperture ring mirror rotates once according to the planned sub-aperture path, the overall surface of the large-aperture ring mirror is obtained.

[0067] This invention requires only one set of detection equipment, which can simultaneously achieve wavelength-level surface shape detection and millimeter-level contour detection without the need for equipment switching, without any assembly or adjustment errors, and saves time and effort.

[0068] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0069] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for detecting the multi-parameter common reference sub-aperture of a large-aperture ring mirror, implemented using a detection device, which includes a light source, a grating, a converging lens, a microlens array, and an imaging module; The light source is positioned on the optical axis of the large-aperture circular mirror to emit a detection beam; A grating is placed on one side of the light source to adjust the direction of the detection beam; The converging lens is positioned in the reflection direction of the large-aperture ring mirror to converge the detection beam reflected by the large-aperture ring mirror. The microlens array is positioned along the transmission direction of the converging lens to split the detection beam into multiple sub-detection beams; The imaging module is used to receive multiple detection beams to detect the surface shape and contour of a large-aperture ring mirror; This detection method includes contour detection and surface shape detection; among which, Contour detection includes the following steps: Step 1: Design sub-apertures for the large-aperture ring mirror; Step 2: Rotate the large-aperture annular mirror according to the planned sub-aperture path; Step 3: Turn on the light source. The emitted detection beam is refracted by the grating and then incident on the test point of the large-aperture ring mirror. Step 4: The detection beam carrying information about the surface of the large-aperture ring mirror, reflected by the point to be measured, is focused by the converging lens and split by the microlens array before being received by the imaging module. Step 5: Calculate the slope of the test point of the large-aperture ring mirror using the imaging module to obtain the contour information of the large-aperture ring mirror; Surface shape detection includes the following steps: Step 1: Design sub-apertures for the large-aperture ring mirror; Step 2: Rotate the large-aperture annular mirror according to the planned sub-aperture path; Step 3: Remove the microlens array from the optical path, and the detection beam emitted by the light source is refracted by the grating and then incident on the test point of the large-aperture ring mirror. Step 4: The detection beam carrying information about the surface of the large-aperture ring mirror, reflected by the test point, is focused by the converging lens and received by the imaging module; Step 5: Calculate the interference fringes at the test point of the large-aperture ring mirror using the imaging module to obtain the surface shape information of the large-aperture ring mirror.

2. The method for detecting the multi-parameter common reference sub-aperture of a large-aperture ring mirror as described in claim 1, wherein the process of calculating the slope of the test point of the large-aperture ring mirror through the imaging module is as follows: Let the highest fitting order be N, and express the wavefront Φ(x,y) as a discrete Fourier series, as shown below: wherein n, m are integers, x, y are discrete spatial coordinates, are discrete Fourier series coefficients, and equation (1) can be transformed to equation (2): Applying gradient operators to both sides of equation (2) establishes... The relationship with the slope S(x,y) is shown in equation (3): Differentiate both sides of formula (3) to obtain the slope of the point to be measured.

3. The method for detecting the multi-parameter common reference sub-aperture of a large-aperture ring mirror as described in claim 1, wherein the formula for calculating the interference fringes at the test point of the large-aperture ring mirror using the imaging module is as follows: wherein I is the intensity of the interference fringes, k is the wavenumber, θ is the angular spectrum, D is the beam aperture, B is the beam spacing, and δ is the optical path difference.

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