<title>Recent Investigations Of Interferometry And Applications To Optical Testing</title>

This paper discusses three recent interferometric optical testing studies being performed at the Optical Sciences Center. First, the design and construction of a 10 μm infrared Twyman-Green interferometer is discussed. The basic specifications of the interferometer are described and results are shown for testing optically rough surfaces having an rms surface height variation as large as 1.38 μm. Second, the use of an infrared point-diffraction interferometer is described and results are presented for testing a germanium lens. The effect of a finite pinhole size on the phase and amplitude uniformity of the reference wavefront is discussed and results are shown for an astigmatic wavefront and a spherically aberrated wavefront. Last, a video interferogram processor being built for analyzing both visible and infrared interferograms is described and interferogram analysis capabilities are discussed and illustrated.