Instantaneous Phase Measuring Interferometry

Conventional phase measuring interferometry normally requires one-half to sixty seconds acquisition time, limiting measurement to stationary phenomena such as optical element wavefronts. We have developed an instantaneous phase measuring interferometer (PMI) that measures displacements at one point to a resolution of 0.003 um. We describe this instrument and an interferometer measuring phase to X/2000 with a measurement time aperture of less than 1 As. Also described is an attached system for analyzing and displaying wavefronts at up to 10 Hz.