Dynamic Deformation Measurement of Specular Surface with Deflectometry and Speckle Digital Image Correlation

Sensors

Shaopu Wang¹  Qun Hao²  Yao Hu²  Chengqiang Xu²  Xuemin Cheng³ 

[1] Beijing Institute of Spacecraft Environment Engineering, Beijing 100094, China;Beijing Key Lab. for Precision Optoelectronic Measurement Instrument and Technology, School of Optics and Photonics, Beijing Institute of Technology, Beijing 100081, China;Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China;

关键词: deformation measurement;    digital image correlation;    deflectometry;    digital speckle;    specular surface;    dynamic measurement;   

DOI  :  10.3390/s20051278

来源: DOAJ

【 摘 要 】

The deformation measurement of a specular surface is of great importance during the quality inspection and installation of optical elements or wafers, especially those with large apertures. We propose a deflectometry method with speckle digital image correlation (DeSDIC) to realize the dynamic and high-accuracy measurement of the deformation on specular surfaces, with a simple system structure and robustness to noises and environmental vibrations. Random speckle pattern displayed on liquid crystal display is reflected by the original surface under test (SUT), and the distorted pattern is recorded by a camera. This originally distorted pattern is taken as the reference image, and the patterns captured afterwards are digitally correlated with the reference image to calculate the gradient change and deformation of the SUT. The theoretical relationships and an experimental one-step calibration scheme are proposed. Both static and dynamic deformations of a deformable mirror were experimentally measured to demonstrate the feasibility and accuracy of DeSDIC, which is comparable to phase-measuring deflectometry and interferometry.

【 授权许可】

Unknown