Two-dimensional virtual grating phase shifting Moiré fringe method of phase extraction

The most useful traditional technique to extract the phase information from a two-dimensional (2D) interferogram is fast fourier transformation (FFT), which is proven to be sensitive to noise. The virtual grating phase shifting Moiré fringe method has not only a good anti-noise characteristic but also a good extraction accuracy. Based on the research of processing the one-dimensional interferogram, a new two-dimensional virtual grating phase shifting Moiré fringe method which can process the two-dimensional interferogram is proposed, which can extract the phase information by generating a 2D virtual grating containing special phase-shift amount. The simulation result between the FFT method and the new method shows that in the case of the interferogram without noise, the relative reconstruction error using the FFT method and the proposed method are 5.52% and 3.46%, respectively. However, the new method has an obvious advantages over the FFT method gradually while the noise increases. Processing the 2D interferogram obtained by the 2D lateral shearing interferometer null test system developed by our research group, the root mean square experiment results of the FFT method and the proposed method are 0.0053 λ and 0.0037 λ (λ=632.8 nm), respectively.