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Proceedings Paper

Extending the range of interferometry through subaperture stitching
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Paper Abstract

Subaperture stitching is a well-known technique for extending the effective aperture or dynamic range of phas measuring interferometers. Stitching has been routinely applied to extend the spatial coverage of plano interferometers. Due to the presence of additional mechanical and optical degrees of freedom, it has been much more difficult to apply stitching techniques to spherical and aspherical interferometric testing. Particular care must be taken in mechanical alignment, motion control, and mathematical processing of subaperture phase data in order to obtain an accurate reconstruction of the full-aperture phase map. We have designed and developed an interferometer workstation specifically to perform high-accuracy subaperture stitching of spherical and flat surfaces up to 200 mm (8") in diameter. The workstation combines a commercial 100 mm (4") Fizeau interferometer, a 6-axis stage, and a software package that automates the entire stitching process. Automation of the measurement design, motion control, phase data acquisition, and data analysis process allows complex stitched measurements to be made in a shop-floor production environment by optical technicians of modest skill. Mathematical techniques were developed to compensate for several classes of systematic and random errors inherent in the measurement process, e.g. motion errors, magnification error, viewing system distortion, and reference wave error. This allows each measurement to be self-calibrated. Basic system capability is demonstrated by comparing a conventional full-aperture phase measurement of a surface to a measurement reconstructed from stitched subapertures.

Paper Details

Date Published: 8 May 2003
PDF: 4 pages
Proc. SPIE TD02, Optifab 2003, (8 May 2003); doi: 10.1117/12.501203
Show Author Affiliations
Paul Dumas, QED Technologies (United States)
Jon Fleig, QED Technologies (United States)
Greg Forbes, QED Technologies (United States)
Paul E. Murphy, QED Technologies (United States)

Published in SPIE Proceedings Vol. TD02:
Optifab 2003
Walter C. Czajkowski; Toshihide Dohi; Hans Lauth; Harvey M. Pollicove, Editor(s)

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