Performance of an Infrared Phase-Shifting Interferometric System

Abstract

An infrared phase-shifting interferometric system has been developed at the University of Arizona Optical Sciences Center. It is a compact, self-contained, easy to align and operate, next generation optical shop instrument. The principle applications for an infrared interferometer are: 1) inspection of infrared materials in transmission for index homogeneity and internal defects, 2) interferometry of surfaces, such as an asphere, whose slopes are too steep for the fringes to be resolved by a visible interferometer, and 3) interferometry of surfaces that are too rough to be tested at visible wavelengths. The advantages of operating an infrared interferometer in the phase-shifting mode are: 1) improved wavefront phase measurement accuracy and resolution 2) the measurement is independent of the beam irradiance distribution and the interferogram fringe contrast, and 3) the wavefront can be sampled and analyzed rapidly over a large two dimensional area.