Calibration of a 300-mm-aperture phase-shifting Fizeau interferometer

A 300-mm-aperture digital phase-shifting Fizeau interferometer has been dev eloped in-house for precision metrology of optical components fabricated by the optical workshop at Telecommunications and Industrial Physics, Commonw ealth Scientific and Industrial Research Organization. We describe the proc edures used in the calibration of the instrument. A reference data file rep resenting the deviations from flatness of the reference surface is generate d, measurement uncertainty estimated, and aberrations in the instrument ass essed. Measurements on 250-mm-diameter uncoated optical surfaces have consi stently shown short-term repeatability of 0.3-nm rms from measurement to me asurement and allowed for absolute characterization of these surfaces to wi thin a few nanometers. (C) 2000 Optical Society of America OCIS codes: 120. 3180, 120.3940, 120.6650, 120.5050, 120.4570, 120.4800.