Instrumentation for Characterizing a New Class of Optical Domes

摘要

New generations of infrared transmitting optical domes are currently being developed for a variety of applications. Traditionally, these domes have been hemispheres, which can be well characterized with conventional optical interferometers. These interferometers, however, are not generally well-suited to the new shapes, such as tangent ogives, because the transmitted and reflected wavefronts can differ by many wavelengths from the planar or spherical wavefronts that are normally used as a reference. In this paper, we present an innovative technique to characterize unconventional optical components such as aspheric domes, mirrors, and freeform optics. The measurements are based on an innovative instrument that combines an instantaneous digital phase-shifting infrared interferometer with a dynamic spatial light modulator that extends the range of the interferometer. The goal of the measurement is to determine the wavefront error, within a small fraction of a wavelength, caused by the deviation of the optical component from a perfect geometrical shape of any type (i.e. not spherical). Experimental results are presented from several infrared components.