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Proceedings Paper

Optical Absolute Encoder Using Spatial Filter
Author(s): Toshitsugu Ueda; Fusao Kohsaka; Toshio Iino; Kunio Kazami; Hiroshi Nakayama
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Paper Abstract

This paper describes a vernier-type optical encoder for absolute angular measurement. The vernier encoder has only two tracks, so it is much smaller and simpler than conven-tional Gray code encoders. Two "spatial filter" detectors are used with the vernier to provide interpolation between encoder slit positions. Each detector consists of a LED light source on one side of the disk, and two photodiode arrays (PDA) -- one for each track of the vernier -- on the other. The two detectors are placed at diametrically-opposed positions, and the intensities of the LED light sources are modulated in quad-rature by a sinusoidal signal. The signals from the detector arrays are combined to generate two vernier signals, and the difference between these vernier signals is a high-precision "absolute vernier" signal. The accuracy of angular measurement for a prototype encoder was as high as 1/10,000 (2.2 arc-min).

Paper Details

Date Published: 17 February 1987
PDF: 5 pages
Proc. SPIE 0814, Photomechanics and Speckle Metrology, (17 February 1987); doi: 10.1117/12.941698
Show Author Affiliations
Toshitsugu Ueda, Yokogawa Electric Corporation (Japan)
Fusao Kohsaka, Yokogawa Electric Corporation (Japan)
Toshio Iino, Yokogawa Electric Corporation (Japan)
Kunio Kazami, Yokogawa Electric Corporation (Japan)
Hiroshi Nakayama, Yokogawa Electric Corporation (Japan)

Published in SPIE Proceedings Vol. 0814:
Photomechanics and Speckle Metrology
Fu-Pen Chiang, Editor(s)

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