Wavefront measurement based on windowed Fourier transform by use of radial shearing interferometer

A wavefront reconstruction technique which obtains wavefront from a radial shearing interferometer with high precision based on two-dimensional windowed Fourier transform (WFT) is presented. First, the radial shearing fringe is processed by WFT, and by inverse WFT after setting threshold and frequency range of integration. Then wavefront phase difference distribution is obtained by the treatment of removal-carrier frequency and phase unwrapping. Finally, the actual wavefront can be reconstructed from phase difference by wavefront iterative algorithm. The simulations show that the maximum phase reconstruction error is 0.82%, RMS is 0.020 9 rad. Also corresponding experiments are conducted for comparison. In addition, window function selection, window size and threshold setting are briefly discussed. Compared with the traditional Fourier transform method (FFT), shearing interferometer wavefront measurement based on windowed Fourier transform has higher precision and stability, which provides a new processing method for wavefront measurement.