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Proceedings Paper

Precise Optical Evaluation Using Phase Measuring Interferometric Techniques
Author(s): Ronald P. Grosso; Robert Crane Jr.
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Paper Abstract

Fabrication of high quality optical surfaces requires both sensitive methods for measuring surface characteristics and delicate control of the fabrication process. Conventional metrology interferometers have been augmented with computer controlled interference phase measuring techniques to give greater accuracy and provide real-time data analysis. Key elements of a Phase Measuring Interferometer (PMI) system are a Twyman-Green interferometer; piezoelectric-driven reference mirror; image detector; and a minicomputer system with a graphic display, keyboard, and hard copier. Surface quality data is obtained by a direct measurement of intensity and computation of phase difference over an aperture containing a 32 x 32 element array. System functions include: isometric contour mapping at variable sensitivity, array subtraction, surface calibration, time averaging, determination of tilt and power over subapertures with respect to a clear aperture, and deconvolution of wavefront data to yield aberration coefficients. The system is being used to produce high-quality reflecting spheres, flats, mirrors, and refractive elements. A measurement uncertainty of <0.01A peak to valley and 0.001 Xrms has been achieved in the evaluation of a large spherical reflector.

Paper Details

Date Published: 25 December 1979
PDF: 10 pages
Proc. SPIE 0192, Interferometry, (25 December 1979); doi: 10.1117/12.957838
Show Author Affiliations
Ronald P. Grosso, The Perkin-Elmer Corporation (United States)
Robert Crane Jr., The Perkin-Elmer Corporation (United States)

Published in SPIE Proceedings Vol. 0192:
George W. Hopkins, Editor(s)

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