Open Access

ARTICLE

Phase-shifting Deflectometric Moiré Topography

Hongwei Guo¹

1 Lab of Applied Optics and Metrology, Department of Precision Mechanical Engineering, Shanghai University, Shanghai, China. Email Address: hw-guo@yeah.net

Structural Longevity 2011, 5(1), 39-47. https://doi.org/10.3970/sl.2011.005.039

Abstract

This paper presents a moiré-based technique for measuring the threedimensional shapes of specular surfaces. In it, a Ronchi grating is closely located before the measured object and illuminated by diffusive light sources. When we observe the measured object through this grating, moiré fringes are generated by the superposition of this grating and its virtual image produced by the measured specular surface. With this scheme, the movements of the grating along the vertical direction introduce phase shifts in these moiré fringes so that their phases can be recovered by use of a self-calibrating phase-shifting algorithm. From the phases and phase shifts, the three-dimensional shape of the specular surface is further reconstructed. Compared with the existing techniques, this method gives a promising solution for measuring complex specular surfaces, because the measured objects can be placed much closer to the grating. The validity of this technique has been demonstrated by an experimental result.

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Keywords

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