Derivative method for dual-wavelength three-frame phase-shifting interferometry

Dual-wavelength interferometry is an important technique, which is widely used in optical measurement and microscopy imaging. In this study, a phase extraction method using derivative algorithm for simultaneous dual-wavelength three-frame phase-shifting interferometry is proposed. Only by calculating the difference between the first and other interferograms as well as its first-order and second-order derivatives, one can separate the information of single-wavelength and obtain continuous phase of the synthetic wavelength. The phase shift can be any value between (0, 2 pi). Simulation and experimental results demonstrate that this method can be used to dual-wavelength on-axis and off-axis interferometric imaging systems with high accuracy. Since only three phase-shifted interferograms are required and only partial derivative algorithm is used, the imaging speed is faster.