Single-shot N-step phase measurement profilometry

Abstract

A single-shot N-step phase measurement profilometry (single-shot N-PMP) is proposed. In the traditional N-step PMP, N (N > 2) frames of phase-shifting sinusoidal gratings are needed to be projected onto the measured object. The corresponding N frames of phase-shifting deformed patterns modulated by the object are needed to be captured. And the larger the N is, the higher the measuring accuracy will be. In the proposed method, only one sinusoidal grating is needed to be projected and only one corresponding deformed pattern is captured. The proposed method can efficiently avoid direct filtering in the spectrum of the deformed pattern because of the secondary modulation in computer. The proposed method is an innovative single-shot, three-dimensional (3D) measurement with the highest accuracy among the single-shot 3D measurements so far for inheriting of the traditional optional N-step PMP. And the optional larger N can result in higher accuracy while the single-shot feature can be always guaranteed both the static and real-time 3D measurements. Furthermore, the mathematical model of the proposed method is more concise compared with the traditional PMP for the phase just modulated by the measured object itself can be directly solved without two phase resolutions and two phase unwrappings for both the reference plane and the measured object. The simulations and experimental results show the feasibility and validity of the proposed method.