<title>Measurement of wavefront structure from large-aperture optical components by phase-shifting interferometry</title>

Abstract

This paper discusses the results of high spatial resolution measurement of the transmitted or reflected wavefront of optical components using phase shifting interferometry with a wavelength of 6328 angstrom. The optical components studied range in size from approximately 50 mm X 100 mm to 400 mm X 750 mm. Wavefront data, in the form of 3D phase maps, have been obtained for three regimes of scale length: 'micro roughness', 'mid-spatial scale', and 'optical figure/curvature'. Repetitive wavefront structure has been observed with scale lengths from 10 mm to 100 mm. The amplitude of this structure is typically 1/100 to 1/20. Previously unobserved structure has been detected in optical materials and on the surfaces of components. We are using this data to assist in optimizing laser system design, to qualify optical components and fabrication processes under study in our component development program.