Remote laser interferometer with pseudo-heterodyne signal processing

Leonid B. Liokumovich; Sergey I. Markov

doi:10.1117/12.407655

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27 November 2000 Remote laser interferometer with pseudo-heterodyne signal processing

Leonid B. Liokumovich; Sergey I. Markov

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Proceedings Volume 4316, International Conference on Lasers for Measurements and Information Transfer; (2000) https://doi.org/10.1117/12.407655
Event: International Conference on Lasers for Measurements and Information Transfer, 2000, St. Petersburg, Russian Federation

Abstract

Optic and fiber optic interference (phase) scheme are successfully used in creating of hydro-acoustic sensors, vibration sensors and measurers of other magnitudes. The most actual type of the interference sensors is a construction which utilize remote passive all optics sensitive interferometer (Fig. 1). In such devices the additional phase modulation and special methods of signal processing are traditionally used. The resolution of the interference sensor is limited by the noise factor of its elements. The final output noise level of the sensor depends of the optical scheme and method of signal processing. This report is devoted to the neutralization of the influence of the light intensity fluctuations on the sensor resolution using pseudo-heterodyne signal processing. Suppression of this factor in phase optical sensors is not often discussed in literature because laser intensity noise is usually insignificant relatively to other noise mechanisms. However in remote sensors with long distance between signal processing unit and sensitive element we have another situation. External influence (acoustics, vibrations) on lead in and lead out optical paths gives an essential income in the intensity noise at the optics exit. This income is especially sizable (up to tens percents) in remote sensors with opened air optical lead in and out. Sometimes they can even make signal measuring impossible.

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Leonid B. Liokumovich and Sergey I. Markov "Remote laser interferometer with pseudo-heterodyne signal processing", Proc. SPIE 4316, International Conference on Lasers for Measurements and Information Transfer, (27 November 2000); https://doi.org/10.1117/12.407655