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Large-aperture optical element surface shape detection method based on stacked coherent diffraction imaging

A technology of coherent diffraction imaging and optical components, which is applied in the direction of using optical devices, measuring devices, image analysis, etc., can solve the problem of small measurement field of view, and achieve the effect of large field of view, simple measurement optical path, and extended measurement range.

Active Publication Date: 2021-07-09
LASER FUSION RES CENT CHINA ACAD OF ENG PHYSICS
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  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is: in order to realize the surface shape measurement of the large-aperture optical element under the pitch angle and solve the technical problem of the small measurement field of view in the existing stacked coherent diffraction imaging technology, the present invention provides a large-aperture coherent diffraction imaging based on stacked coherent diffraction imaging Optical component surface shape detection method

Method used

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  • Large-aperture optical element surface shape detection method based on stacked coherent diffraction imaging
  • Large-aperture optical element surface shape detection method based on stacked coherent diffraction imaging
  • Large-aperture optical element surface shape detection method based on stacked coherent diffraction imaging

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Embodiment 1

[0038] Such as figure 1 and figure 2 As shown, a large-aperture optical component surface shape detection method based on stacked coherent diffraction imaging, the component to be tested is located at the parallel light after beam expansion and collimation, and the parallel light aperture is limited by the collimator lens aperture. Considering the measurement efficiency, lens processing difficulty and cost factors, the general collimator lens diameter can be 100mm~200mm. Including the following steps:

[0039] Step 1. Move the component to be tested to the initial sub-aperture scanning position and align it, and use the camera to collect the diffraction spot image at the initial sub-aperture scanning position;

[0040] Step 2. Translate the component to be measured to the next sub-aperture scanning position and collect the diffraction spot image corresponding to the sub-aperture scanning position. Adjacent sub-apertures have overlapping areas, and the component to be measur...

Embodiment 2

[0060] This embodiment provides a method for automatically extracting the center of a cross figure based on least squares fitting iterations, the steps are as follows:

[0061] Step 1. Move the component to be tested to the initial scanning position and perform alignment; the surface shape distribution of the component to be tested simulated in this embodiment is as follows: image 3 As shown, the component size is 400mm×400mm, the component surface PV is 0.5λ (λ=632.8nm), and the measuring beam aperture is 100mm.

[0062] Step 2. Use a camera to collect the diffraction spot; the simulated camera in this embodiment has a pixel resolution of 1000×1000 and a pixel size of 5 μm.

[0063] Step 3. Translate the component to be tested to the next scanning position and collect the diffraction spot. The sub-apertures of adjacent scanning positions must have a certain overlapping area; the ratio of the area of ​​the overlapping area to the area of ​​the sub-aperture is 60%.

[0064] S...

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Abstract

The invention discloses a large-aperture optical element surface shape detection method based on stacked coherent diffraction imaging, relates to the technical field of optical detection and digital image processing, solves the technical problem of small measurement view field in the existing stacked coherent diffraction imaging technology, and realizes surface shape measurement of a large-aperture optical element. Comprising the following steps: moving a to-be-measured element to an initial sub-aperture scanning position and performing alignment; acquiring diffraction spots by using a camera; the element to be measured is translated to the next sub-aperture scanning position, diffraction spots are collected, and sub-apertures at the adjacent sub-aperture scanning positions need to have a certain overlapping area; the scanning sub-aperture light spot covers the to-be-detected area of the optical element; processing the collected series of diffraction images, and recovering the surface shape distribution of the to-be-measured element by adopting a stacked coherent diffraction imaging iterative algorithm; the device is used for detecting the surface shape of the large-aperture optical element, and has the advantages of large measuring aperture, simple optical path and low cost.

Description

technical field [0001] The present invention relates to the technical field of optical detection and digital image processing, and more specifically to the technical field of a large-diameter optical element surface shape detection method based on lamination coherent diffraction imaging, which is used for large-diameter optical element surface shape detection. Background technique [0002] When the light field propagates in free space, the complex amplitude of the light field will change due to the diffraction effect of light. According to the principle of Fresnel diffraction, if the complex amplitude distribution of the light field at a certain position is known, the complex amplitude distribution of the light field after a certain distance can be calculated under paraxial conditions. If only the intensity distribution of the light field is known, theoretically it is necessary to know the intensity distribution of the light field at two positions along the optical axis. Usi...

Claims

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Application Information

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IPC IPC(8): G01B11/24G06T7/60
CPCG01B11/24G06T7/60
Inventor 刘勇刘旭李东陈竹石振东马骅巴荣声姜宏振何宇航任寰柴立群朱启华
Owner LASER FUSION RES CENT CHINA ACAD OF ENG PHYSICS
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