High-speed FM demodulator of a homodyne laser interferometer for measuring mechanical vibration

Jongpil La; Semyung Wang; Koungsuk Kim; Kyihwan Park

doi:10.1117/1.1715097

1 June 2004 High-speed FM demodulator of a homodyne laser interferometer for measuring mechanical vibration

Jongpil La, Semyung Wang, Koungsuk Kim, Kyihwan Park

Author Affiliations +

Optical Engineering, Vol. 43, Issue 6, (June 2004). https://doi.org/10.1117/1.1715097

Abstract

A high-speed FM demodulation method for measuring mechanical vibration using a homodyne laser interferometer is presented. The Doppler frequency, which represents the surface velocity of a vibrating object, is obtained by using the homodyne laser interferometer, and converted to a voltage signal by using the proposed analogue FM demodulation circuit. The dc offsets of the interference signals obtained from the homodyne laser interferometer are eliminated by using simple subtraction. The new method for compensation of the asymmetry of each interference signal is presented. The laser power variation of the interferometer is normalized by using an auto-gain controller (AGC). The performance of the proposed FM demodulation algorithm is proved by using theoretical methods, and validated by using experimental results. In the experiments, the proposed FM demodulation algorithm is compared with a conventional demodulation method.

©(2004) Society of Photo-Optical Instrumentation Engineers (SPIE)

Citation Download Citation

Jongpil La, Semyung Wang, Koungsuk Kim, and Kyihwan Park "High-speed FM demodulator of a homodyne laser interferometer for measuring mechanical vibration," Optical Engineering 43(6), (1 June 2004). https://doi.org/10.1117/1.1715097

Published: 1 June 2004

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