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Proceedings Paper

Measurement of the radius of curvature of a mini spherical surface with virtual grating phase shift technique
Author(s): Yongxiang Xu
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Paper Abstract

Spherically optical components of small diameters have found wide applications in many fields. Radius of curvature (ROC) is an important parameter as it determines their optical characteristics. For measuring the ROC of a mini spherical surface, a static microscopic carrier interferogram is taken, and virtual grating phase shift technique (VGPT) is adopted in this paper. By using the computer, four virtual gratings are generated, their reference frequency being the same as the carrier frequency of the test interferogram, and their modulation phases being 0, π/2, π and 3π/2, respectively. By multiplying the test interferogram separately with the four virtual gratings in intensity, four moiré fringe images are obtained. By applying Furrier transform and low pass filtering, a set of four carrier-free phase shift fringe images are obtained. And finally by applying four step phase shifting algorithm and least square fitting (LSF), the ROC of the test spherical surface is obtained. Furthermore, the result agrees well with its nominal value and measurement result by Zygo interferometer. This indicates that adopting VGPT for measuring ROCs of mini spherical surfaces is practicable and has relatively a high accuracy.

Paper Details

Date Published: 9 November 2010
PDF: 10 pages
Proc. SPIE 7849, Optical Design and Testing IV, 78492S (9 November 2010); doi: 10.1117/12.870686
Show Author Affiliations
Yongxiang Xu, Nanjing Univ. of Science & Technology (China)

Published in SPIE Proceedings Vol. 7849:
Optical Design and Testing IV
Yongtian Wang; Julie Bentley; Chunlei Du; Kimio Tatsuno; Hendrik P. Urbach, Editor(s)

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