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Spatially-Phase-Shifted Coherent Gradient Sensor for Full-Field Measurement of Surface Slope and Curvature

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Abstract

In this study, a spatial phase stepping method for coherent gradient sensing is developed to automatically measure the reflective surface slopes, curvatures and shapes in dynamic problems. A beam-splitting system and a spatial phase stepping system are designed to obtain four interferograms with different phase shifting steps in one shot. The post processing can automatically generate accurate full-field plots of the slope field components using the four interferograms per frame and the four-step phase shifting algorithm. The surface curvatures and shapes can be calculated numerically using the slopes. To verify this method, a thermal shock experiment is conducted using a reflecting mirror with a dielectric film. The highest temperature achieved during thermal shock was 672 °C. The frame rate is 25 fps and the results of every frame are obtained automatically. Experiments demonstrate the applicability of the proposed spatial phase stepping method.

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Acknowledgments

The authors are grateful to the financial support from the National Natural Science Foundation of China (Grant Nos. 11232008, 91216301, 11227801, 11172151), Tsinghua University Initiative Scientific Research Program.

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Authors and Affiliations

  1. AML, Department of Engineering Mechanics, Tsinghua University, Beijing, 100084, China

    K. Ma & H. Xie

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  1. K. Ma
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  2. H. Xie
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Correspondence to H. Xie.

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Ma, K., Xie, H. Spatially-Phase-Shifted Coherent Gradient Sensor for Full-Field Measurement of Surface Slope and Curvature. Exp Mech 56, 1073–1082 (2016). https://doi.org/10.1007/s11340-016-0153-2

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  • DOI: https://doi.org/10.1007/s11340-016-0153-2

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