Reflector surface shape detection system and detection method

Abstract

The present invention provides a reflector detection system and method, wherein the detection system includes: an interferometer, a flange structure, a vacuum container, and a CGH. The interferometer is used to emit a detection beam that is incident on the flange structure located at the focal position of the detection beam. The flange structure is provided with a tapered light hole, and the detection beam is incident on the vacuum container after passing through the tapered light hole. The CGH and the reflector to be measured are provided in the vacuum container. The detection beam passes through the CGH and is incident on the reflector to be measured. The vacuum container is adjusted to a preset air pressure range to perform surface shape detection on the reflector to be measured. By transmitting light at the focal point, the present invention avoids the use of a vacuum environment window reflector surface shape detection method. The characteristics of the present invention are more intuitive detection results, high accuracy, low cost, and simple and easy implementation.

Description

Technical Field

[0001] The present invention relates to the technical field of optical detection, and in particular to a reflector surface shape detection system and a detection method thereof. Background Art

[0002] Reflectors are essential components of optical satellite payloads. As the payload capacity of optical satellites increases, the diameter of reflectors is getting larger and larger. However, the resulting impact is that the reflectors are more seriously affected by airflow during processing and inspection, resulting in large differences in their surface shapes in vacuum environments and normal pressure environments. This makes it difficult to ensure the consistent performance of optical satellite payloads between the ground and the sky. Based on the above problems, some engineering researchers have proposed a method for detecting the surface shape of reflectors in a vacuum environment. However, since the precise and expensive instrument interferometer used for reflector surface shape detection cannot be used in a vacuum environment, some people have adopted the method of setting up a normal pressure container in a vacuum environment to provide the required normal pressure working environment for the interferometer. Then, by setting a glass window on the normal pressure container, the detection light of the interferometer is incident on the vacuum environment, and then the surface shape of the inspected reflector is detected.

[0003] Conventional methods for measuring the surface shape of reflectors in a vacuum environment introduce a window into the detection optical path, which results in window errors being superimposed on the detection. To obtain the true surface shape of the reflector, data processing is required to subtract the window-induced errors. However, the spherical aberration introduced by a typical window to the detection result is far greater than the target surface shape to which the reflector is ultimately machined. Therefore, methods that subtract large errors from a high-precision surface shape are unlikely to guarantee high accuracy. Simultaneously adding a window for detection requires not only the development of high-precision window glass but also extensive data processing, increasing costs while significantly reducing detection efficiency. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to propose a reflector surface shape detection system and a detection method thereof, which uses light transmission at the focus and does not use a window to detect the surface shape of a reflector in a vacuum environment. The method has the characteristics of more intuitive detection results, high accuracy, low cost, and simplicity and ease of implementation.

[0005] To achieve the above objectives, the present invention adopts the following specific technical solutions:

[0006] The present invention provides a reflector detection system, comprising: an interferometer, a flange structure, a vacuum container and a CGH;

[0007] The interferometer is used to emit a detection light beam that is incident on the flange structure located at the focal position of the detection light beam; the flange structure is provided with a tapered light hole, and the detection light beam is incident on the vacuum container after passing through the tapered light hole. The vacuum container is provided with a CGH and a measured reflector, and the detection light beam is incident on the measured reflector through the CGH, and the vacuum container is adjusted to a preset air pressure to perform surface detection on the measured reflector.

[0008] Preferably, the flange structure is placed outside the vacuum container, and a conical light hole is provided at the center of the flange structure. The diameter of the conical light hole is larger on the side close to the vacuum container and smaller on the side away from the vacuum container; the diameter of the conical light hole is 3mm to 5mm.

[0009] Preferably, the detection beam is aligned by adjusting the CGH and the detected reflector in five degrees of freedom respectively.

[0010] Preferably, when the reflector to be measured is a spherical reflector, the reflector detection system does not include a CGH.

[0011] Preferably, the reflector detection system is placed on a vibration isolation platform for detection.

[0012] The present invention also provides a reflector detection method, comprising the following steps:

[0013] S1. Adjust the position of the interferometer so that the focus of the detection beam emitted by the interferometer is located at the center of the tapered light hole of the flange structure;

[0014] S2. Keep the interferometer fixed and adjust the position of the CGH and the detected reflector until the detection beam returns to the interferometer, completing the self-alignment of the detection light path.

[0015] S3. Use adhesive strips to stick the tapered light hole, seal the vacuum container, and then perform vacuuming.

[0016] S4. Remove the rubber strip, keep the air pressure in the vacuum container lower than the preset air pressure range, and perform surface shape detection on the reflector to be measured.

[0017] Preferably, step S4 includes the following sub-steps:

[0018] S41. When the air pressure in the vacuum container drops to a preset pressure range, remove the rubber strip to perform surface shape detection on the reflector to be measured.

[0019] S42. When the air pressure in the vacuum container rises to a level that affects the accuracy of the measured reflector surface shape detection, the tapered light hole is pasted again with adhesive strips.

[0020] S43. Repeat steps S41-S42 until the surface shape detection of the reflector under test is completed.

[0021] Preferably, the preset air pressure range is 1X10 -1 pa~1X10 -3 pa.

[0022] Preferably, during the surface shape detection process of the reflective mirror to be measured, the vacuum container is continuously evacuated until the surface shape detection of the reflective mirror to be measured is completed.

[0023] Compared with the existing technology, the present invention uses a vacuum environment reflector surface shape detection method that transmits light at the focus without using a window, and has the characteristics of more intuitive detection results, high accuracy, low cost, and simplicity and ease of implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 2 is a schematic structural diagram of a reflector detection system provided according to an embodiment of the present invention.

[0025] Figure 2 Schematic diagram of the flange structure of a reflector detection system provided according to an embodiment of the present invention.

[0026] Figure 3 4 is a flow chart of a reflector detection method provided according to an embodiment of the present invention.

[0027] The reference numerals include: interferometer 1, flange structure 2, vacuum container 3, CGH 4, and inspected reflective mirror 5. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0030] Figure 1 A schematic structural diagram of a reflector detection system provided according to an embodiment of the present invention is shown.

[0031] like Figure 1 As shown, the reflector detection system provided by the embodiment of the present invention includes: an interferometer 1, a flange structure 2, a vacuum container 3 and a CGH 4.

[0032] The interferometer 1 is a ZYGO interferometer, which is placed in a normal pressure environment and is used to emit a detection light beam to be incident on the flange structure 2.

[0033] Figure 2A schematic diagram of the flange structure of a reflector detection system provided according to an embodiment of the present invention is shown.

[0034] like Figure 2 As shown, flange structure 2 is placed on one of the side walls of vacuum container 3. A tapered light hole is provided at the center of flange structure 2. The diameter of the tapered light hole gradually increases along the propagation direction of the detection beam. That is, the diameter of the tapered light hole of flange structure 2 is larger on the side close to vacuum container 3 and smaller on the side away from vacuum container 3. The diameter of the tapered light hole is 3 mm to 5 mm, and the taper of the tapered light hole is greater than the taper of the detection beam emitted by interferometer 1.

[0035] The test beam passes through the tapered aperture in the flange structure, then passes through the CGH4 and is incident on the inspected reflector 5. The CGH4 and inspected reflector 5 are positioned within the vacuum chamber 3 along the test optical path, with the CGH4 positioned close to the perforated flange structure 2. Both the CGH4 and inspected reflector 5 can independently adjust within the vacuum chamber 3 using five degrees of freedom (no rotational adjustment required about the optical axis). The CGH's function is to compensate for aspheric mirrors when inspecting them, converting them into spherical waves, facilitating interferometric measurement of the reflector's surface shape using an interferometer.

[0036] The detection light beam is reflected by the inspected reflective mirror 5 and then returns to the interferometer 1 to obtain the detection result of the inspected reflective mirror.

[0037] Figure 3 A schematic flow chart of a reflector detection method according to an embodiment of the present invention is shown.

[0038] The reflector detection method provided by the embodiment of the present invention includes the following steps:

[0039] S1. Adjust the position of the interferometer so that the focus of the detection light beam emitted by the interferometer is located at the center of the tapered light hole of the flange structure.

[0040] A detection interferometer is placed on the outside of the vacuum container, facing the tapered hole of the flange. By adjusting the front and rear positions of the interferometer, the focus of the spherical wave emitted by the interferometer, that is, the detection beam, is exactly at the minimum hole position of the tapered light hole, that is, the center position.

[0041] S2. Keep the interferometer fixed and adjust the position of the CGH and the detected reflector in the vacuum container until the detection beam returns to the interferometer, completing the self-alignment of the detection light path.

[0042] S3. Use adhesive strips to stick the tapered light hole, so that the vacuum container is in a closed state and then vacuum treatment is performed.

[0043] The adhesive strip is pasted outside the vacuum container.

[0044] S4. Remove the rubber strip, keep the air pressure in the vacuum container lower than the preset air pressure range, and perform surface shape detection on the reflector to be measured.

[0045] The preset air pressure range is 1X10 -1 pa~1X10 -3 pa.

[0046] Step S4 includes the following sub-steps:

[0047] S40, pre-processing step: keep the vacuum container evacuated until the surface shape detection of the reflector to be measured is completed.

[0048] S41. When the air pressure in the vacuum container drops to a preset pressure range, remove the rubber strip to perform surface shape detection on the reflector to be measured.

[0049] S42. When the air pressure in the vacuum container rises to a level that affects the accuracy of the measured reflector surface shape detection, the tapered light hole is sealed again with a tapered seal.

[0050] S43. Repeat steps S41-S42 until the surface shape detection of the reflector under test is completed.

[0051] The preset air pressure does not have to be 1X10 -3 pa, the appropriate low pressure test range can be selected according to the actual sensitivity of the reflector to airflow.

[0052] The present invention is also applicable to the surface shape detection of a spherical reflector, in which case no CGH is required in the optical path and only the reflector to be detected is placed in the vacuum container.

[0053] To prevent vibration interference, all testing instruments and equipment, including interferometers and vacuum containers, must be placed on a vibration isolation platform for testing.

[0054] To ensure that the detection beam emitted by the interferometer is not blocked by the tapered light hole, after the initial interferometer position adjustment, the relative position of the interferometer and the vacuum container must be kept stable. During detection, the alignment accuracy of the detection light path must be adjusted by adjusting the position of the reflector.

[0055] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0056] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A reflector detection system, characterized in that: include: Interferometer, flange structure, vacuum container and CGH; The interferometer is used to emit a detection beam that is incident on a flange structure located at the focal position of the detection beam; the flange structure is provided with a tapered light hole, and the detection beam is incident on the vacuum container after passing through the tapered light hole; a CGH and a measured reflector are provided in the vacuum container, and the detection beam is incident on the measured reflector through the CGH, and the vacuum container is adjusted to a preset air pressure to perform surface shape detection on the measured reflector; The flange structure is placed outside the vacuum container, and a tapered light hole is provided at the center of the flange structure. The diameter of the tapered light hole is larger on the side close to the vacuum container and smaller on the side away from the vacuum container; the diameter of the tapered light hole is 3mm~5mm.

2. The reflector detection system according to claim 1, characterized in that: The detection beam is aligned by performing five-degree-of-freedom adjustments on the CGH and the measured reflector respectively.

3. The reflector detection system according to claim 2, characterized in that: When the reflector to be measured is a spherical reflector, the reflector detection system does not include a CGH.

4. The reflector detection system according to claim 3, characterized in that: The reflector detection system is placed on a vibration isolation platform for detection.

5. A detection method for a reflector detection system according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Adjust the position of the interferometer so that the focus of the detection light beam emitted by the interferometer is located at the center of the tapered light hole of the flange structure; S2, keeping the interferometer fixed, adjusting the positions of the CGH and the measured reflector until the detection beam returns to the interferometer, completing the self-alignment of the detection optical path; S3, using adhesive strips to stick the tapered light hole, so that the vacuum container is in a sealed state and then evacuates the vacuum container; S4. Remove the rubber strip, maintain the air pressure in the vacuum container below a preset air pressure range, and perform a surface shape test on the reflector to be tested.

6. The detection method of the reflector detection system according to claim 5, characterized in that: The step S4 includes the following sub-steps: S41, when the air pressure in the vacuum container drops to the preset air pressure range, removing the adhesive strip to perform surface shape detection on the reflector to be measured; S42, when the air pressure in the vacuum container rises to a level that affects the detection accuracy of the measured reflective mirror surface shape, the tapered light hole is again adhered with the adhesive strip; S43. Repeat steps S41-S42 until the surface shape detection of the reflector under test is completed.

7. The detection method of the reflector detection system according to claim 6, characterized in that: The preset air pressure range is 1X10 -1 pa~1X10 -3 pa.

8. The detection method of the reflector detection system according to claim 7, characterized in that: During the surface shape detection process of the reflective mirror to be measured, the vacuum container is continuously evacuated until the surface shape detection of the reflective mirror to be measured is completed.

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