Circular-path polarization point-diffraction interferometer and analysis of the fringe parameters

A circular-path polarization point-diffraction interferometer (PDI) is developed, in which the reference and test waves travel in a nearly same optical path and in opposite directions. Furthermore, a linear tilting modulation can be introduced into two interfering waves by rotating the polarization beam splitter (PBS). As a result, the fringe pattern with carrier frequency is captured and the Fourier transform method is employed to extract the tested wavefront. Furthermore, by analyzing the fringe parameters. i.e., fringe contrast and carrier frequency, it can be concluded that the proposed PDI can adjust easily these two fringe parameters. Therefore, the fringe pattern with the highest contrast and suitable carrier frequency can be captured, and so as this PDI with compact configuration can also obtain high accuracy of phase meausrement. (C) 2018 Elsevier GmbH. All rights reserved.