Improved Fourier transformation based method for accurate phase and amplitude retrieval in spectral interferometry

Although Fourier transformation (FT) is the most commonly used method to retrieve the phase and amplitude information of a spectral interferogram, its accuracy is usually degraded due to effects such as fringe truncation, uneven distribution of fringes, noise and fringe density, etc. In this work, we propose an improved FT based method to process the spectral interferogram. By using a Gaussian envelope and a self-designed flat-top cap window function, significant improvements in accuracy and robustness can be achieved compared to the conventional FT method. Besides, by analyzing the correlation between the fringe density and the data processing error, the optimal configuration in an actual spectral interferometry experiment can be screened out. At last, we have applied the proposed method on the actual spectral interferograms obtained in our laser-induced shock wave loading experiment for effectiveness demonstration, and the results show a dramatical reduction of the measurement error compared to the traditional FT method. (paper)