Arbitrary phase shifting method for fiber-optic fringe projection profilometry based on temporal sinusoidal phase modulation

Abstract

A new arbitrary phase shifting method is proposed in this paper for fiber-optic fringe projection profilometry. By introducing a small temporal sinusoidal phase modulation to the phase shift and employing the phase-generated carrier (PGC) method, the time-varying interference phase α(t)can be demodulated from the Michelson interference signal, which is reflected by the fiber end faces and recorded concurrently with the recording of the fringe pattern. Integrate sin [α(t)] and cos [α(t)] respectively, and then the phase shifts between frames can be determined and consequently used to solve the phase map with least-squares PS algorithm. The noise model of this method is deduced from which the optimum modulation amplitude can be selected. In the experiment, four fringe patterns with uncalibrated phase shifts were recorded under strong environmental disturbance, and were analyzed by utilizing the Carre algorithm, the proposed method and the modified Fourier transform (MFT) method respectively. A visual criterion is used to evaluate the performances of these methods. Experimental results indicate that the proposed method is much more robust to phase shift miscalibration than the Carre algorithm, and its performance is comparable to that of the MFT method while its computational complexity is substantially lower. Therefore, the proposed method is suitable for real-time phase shift calibration.