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Optical Engineering

Analysis of diffraction spectra for measuring surface form of spheric and rotationary symmetric aspheric components
Author(s): Haiming Wang; Hanyu Mi
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Paper Abstract

Measurements of aspheric surfaces by interferometry are possible but technically complicated. We present a simple laser-CCD camera setup based on the analysis of diffraction spectra for the surface form measurement. A slit is illuminated by a helium neon laser beam. A sample surface works as a mirror to direct the diffraction spectra of the slit to the CCD camera. The surface form of the sample redistributes the intensity of the diffraction spectra. This enables us to reconstruct the surface form from the measured diffraction spectra. This method has two particular features. First, no reference surface is necessary and therefore there is no special difficulty in measuring aspheric surfaces. Moreover, in comparison with the common focal plane light intensity measurement, we measure the light intensity distribution in the diffraction plane (the diffraction spectrum). It is not necessary to measure a very sharply dropping intensity distribution. In turn we do not need a detector with very broad dynamic range and very high special resolution.

Paper Details

Date Published: 1 September 1997
PDF: 5 pages
Opt. Eng. 36(9) doi: 10.1117/1.601482
Published in: Optical Engineering Volume 36, Issue 9
Show Author Affiliations
Haiming Wang, Centro de Investigaciones en Optica, AC (United States)
Hanyu Mi

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