Improving Phase Retrieval Accuracy Of Optical Parallel Plate By Adjusting Exposure Time Of Ccd

A new phase retrieval method is investigated to reconstruct wavefronts of optical parallel plates with the use of a group of diffraction patterns. More specifically, the improved phase retrieval algorithm is realized by converting the measuring plane wave into a spherical wave and by using single or double discrete Fourier transforms to calculate both far- and near-field diffraction propagations, and the accuracy is improved by adjusting the exposure time of the charge-coupled device according to the distance between the focal plane and diffraction plane. Both the theoretical and experimental results are consistent with the results obtained using conventional wavelength-modulated phase-shifting interferometry. The new method opens new doors for realizing wavefront measurement of optical parallel plates with high accuracy, especially for large-aperture parallel plates in inertial confinement fusion laser systems.