Dynamic wavefront measurement with a pinhole linear polarizer point-diffraction interferometer.

We propose a pinhole linear polarizer point-diffraction interferometer (PLP-PDI) for dynamic wavefront measurements. The proposed interferometer uses a metallic wire grid linear polarizer that acts as a point-diffraction plate to generate an ideal spherical wave, from which we can obtain orthogonally polarized reference and test beams. The special polarization phase-shifting configuration allows four phase-shifted interferograms to be captured in a single shot with high precision and stability. The wavefront can then be reconstructed using a phase-unwrapping algorithm. In this paper, we describe the theory of the PLP-PDI and analyze the possible errors introduced by the device. The feasibility of the proposed PLP-PDI was verified by direct measurements of a wavefront. The experimental results show that the proposed PLP-PDI is an effective and efficient tool for the dynamic measurement of wavefronts.