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Proceedings Paper

Reflective-type optical encoder based on fractional Talbot self-image effect using phase grating
Author(s): Ching-Fen Kao; Sheng-Hua Lu
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Paper Abstract

This study presents a reflective-type optical encoder based on fractional Talbot self-image effect using a phase grating. An amplitude grating image is produced by the phase grating at a quarter or three quarters of Talbot distance. The encoder has the advantages of a large gap and more light efficiency. This work use a 850nm Light-Emitting Diode (LED) as light source, the light source will be collimated by a collimator ,and incident on a phase grating by 45° angle. The fractional Talbot self-image of phase grating is produced and projected on an amplitude index grating. The Moiré interference is occurred when the both gratings displaced from each other. The encoder includes a reflective-type phase-grating scale with period 20 μm and an index-amplitude grating. The gap between the phase index grating and mail scale was increased to three quarters of Talbot distance. The tolerance of gap between the index and main grating is 0.1 mm. The tolerance of yaw motion is ± 0.25°.

Paper Details

Date Published: 28 December 2010
PDF: 6 pages
Proc. SPIE 7544, Sixth International Symposium on Precision Engineering Measurements and Instrumentation, 75440N (28 December 2010); doi: 10.1117/12.886238
Show Author Affiliations
Ching-Fen Kao, MingDao Univ. (Taiwan)
Sheng-Hua Lu, Feng Chia Univ. (Taiwan)


Published in SPIE Proceedings Vol. 7544:
Sixth International Symposium on Precision Engineering Measurements and Instrumentation
Jiubin Tan; Xianfang Wen, Editor(s)

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