Polarization phase-shifting point-diffraction interferometer

Abstract

A new instrument, the polarization phase-shifting point-diffraction interferometer (PPSPDI), is developed utilizing a birefringent pinhole plate. The interferometer uses polarization to separate the test and reference beams, interfering what begin as orthogonal polarization states. The instrument combines the robust nature of Linnik's original point-diffraction interferometer with the ability to phase-shift for interferogram analysis. The instrument is compact, simple to align, vibration insensitive and can phase-shift without moving parts or separate reference optics. This dissertation describes the theory, design, application and manufacturing considerations of the PPSPDI. The original PDI design is expanded to include polarization and phase-shifting. The discussion includes the properties of the birefringent material used as well as various fabrication methods used for creating the pinhole. A new model is developed to determine the quality of the diffracted reference wavefront from the pinhole as a function of pinhole size and aberrations of the test optic. The operation and performance of the interferometer are also presented along with a detailed error analysis and performance limits of the design.