Quantitative evaluation of the defocusing degree in fringe projection profilometry

Cong Liu; Zhuoyi Yin; Xiaopeng Liu; Zhihong Xu

doi:10.1117/12.2541641

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16 October 2019 Quantitative evaluation of the defocusing degree in fringe projection profilometry

Cong Liu, Zhuoyi Yin, Xiaopeng Liu, Zhihong Xu

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Proceedings Volume 11205, Seventh International Conference on Optical and Photonic Engineering (icOPEN 2019); 1120509 (2019) https://doi.org/10.1117/12.2541641
Event: Seventh International Conference on Optical and Photonic Engineering (icOPEN 2019), 2019, Phuket, Thailand

Abstract

Camera/projector defocusing is a method of generating sinusoidal images for binary images in fringe projection profilometry. While the most appropriate degree of defocus is often difficult to determine. Therefore, in this paper, it is proposed a defocusing degree evaluation algorithm. This algorithm is to calculate the image gray value error E of the fitted sinusoidal image and the actual image based on image difference and Levenberg-Marquardt (LM) iteration method. Firstly, differential operation is performed on the image captured by the camera. And then, the LM iteration method is executed on the difference image. The phase fluctuation error E_M is quantitatively described as E ∙ S α by image gray range S, where α is constant which can be determined experimentally. For a system with no defocusing, the measured phase fluctuation error of ± 0.05 radian, this can be reduced to ± 0.01 radian under the optimal defocus degree obtained by this method. The algorithm can handle one image within 20 ms, which meets the requirements of real-time calculation.

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Cong Liu, Zhuoyi Yin, Xiaopeng Liu, and Zhihong Xu "Quantitative evaluation of the defocusing degree in fringe projection profilometry", Proc. SPIE 11205, Seventh International Conference on Optical and Photonic Engineering (icOPEN 2019), 1120509 (16 October 2019); https://doi.org/10.1117/12.2541641

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