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Proceedings Paper

Liquid crystal grating for profilmetry using structured light
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Paper Abstract

This paper describes a liquid crystal (LC) device for three dimensional profile measurement systems which are based on grating projection method using phase shifting technique. As a key component to these sytems, we propose to apply a liquid crystal (LC) grating instead of a conventional ruled grating because the grating ruled on the glass plate has difficulty in speedy and accurate shifting of the pattern. This LC grating consists of 960 lines of stripe pattern on the substrate of 60x40 mm2 in size and has such features as 8 bits of gray levels in dynamic range for mono-chromatic usage. A sinusoidal pattern as well as a binary pattern is realized by combining pulse width modulation control (PWMC) and frame ratio control (FRC) technique. The period of the pattern is arbitrarily controlled and, in addition, shifting of the projected pattern is also electrically realized. We present properties of the LC grating we have developed and demonstrate a few examples obtained by the system which has this LC grating built in.

Paper Details

Date Published: 7 November 2005
PDF: 10 pages
Proc. SPIE 6000, Two- and Three-Dimensional Methods for Inspection and Metrology III, 60000H (7 November 2005);
Show Author Affiliations
Toru Yoshizawa, Tokyo Agriculture and Technology Univ. (Japan)
Hiroo Fujita, Citizen Active Co., Ltd. (Japan)

Published in SPIE Proceedings Vol. 6000:
Two- and Three-Dimensional Methods for Inspection and Metrology III
Kevin G. Harding, Editor(s)

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