Three-Dimensional Shape Measuring Method Based on Dual-Frequency Digital Moiré Fringe

Abstract

A dual-frequency digital Moiré measurement method (DFDM) is proposed for the three-dimensional (3D) shape measurement of an object. The high- and low-frequency fringes are modulated separately along orthogonal direction using different carrier frequencies before being projected onto the measured object. After collecting and demodulating the composite fringe, the digital π phase shift is used to remove the DC component of the demodulated fringes, resulting in high-precision Moiré fringes for calculating the wrapped phase. The unwrapping of the high-frequency wrapped phase is guided by the low-frequency phase to further realistically reconstruct the surface of the measured object. When compared with existing single-shot digital Moiré profilometry, DFDM effectively removes the DC component of the fringe and calculates the phase more accurately.A dual-frequency digital Moiré measurement method (DFDM) is proposed for the three-dimensional (3D) shape measurement of an object. The high- and low-frequency fringes are modulated separately along orthogonal direction using different carrier frequencies before being projected onto the measured object. After collecting and demodulating the composite fringe, the digital π phase shift is used to remove the DC component of the demodulated fringes, resulting in high-precision Moiré fringes for calculating the wrapped phase. The unwrapping of the high-frequency wrapped phase is guided by the low-frequency phase to further realistically reconstruct the surface of the measured object. When compared with existing single-shot digital Moiré profilometry, DFDM effectively removes the DC component of the fringe and calculates the phase more accurately.

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