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Proceedings Paper

Two-frequency laser measuring technique with high axis velocity
Author(s): Fengzhou Fang; Bryan Kok Ann Ngoi
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Paper Abstract

Interferometers using heterodyne techniques are now widely employed for displacement measurements. Heterodyne interferometric techniques involve the use of two beams derived from the same laser, one of which has its frequency shifted by a specified amount. A helium-neon laser is forced to oscillate simultaneously at two frequencies separated by a constant difference of about 2 MHz, by applying an axial magnetic field. But the axis-velocity with this method is not able to be increased for a small frequency difference. An effective way of introducing such a frequency shift is by means of an acousto-optic modulator. It is studied in detail after a few methods are discussed for increasing the frequency difference. The measuring system will be used widely in displacement, objective with high speed motion of 1.8 m/s and on-line measurement.

Paper Details

Date Published: 29 September 1998
PDF: 4 pages
Proc. SPIE 3407, International Conference on Applied Optical Metrology, (29 September 1998); doi: 10.1117/12.323356
Show Author Affiliations
Fengzhou Fang, Nanyang Technological Univ. (China)
Bryan Kok Ann Ngoi, Nanyang Technological Univ. (Singapore)

Published in SPIE Proceedings Vol. 3407:
International Conference on Applied Optical Metrology
Pramod Kumar Rastogi; Ferenc Gyimesi, Editor(s)

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