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14 April 1999 Novel optical vibration sensor using external cavity feedback
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A novel low cost, non-contact optical vibration sensor requiring only a single optoelectronic component has been developed. It consists of a CW semiconductor laser operating with external optical feedback. The laser beam reflected from a target generates a series of lasing modes set by the external cavity length. Beating of the modes produces an RF signal and this signal is detected as a variation in the junction voltage. Any change in the external cavity length induces corresponding beat frequency variations in the RF signal, which are transformed into amplitude variations using a simple edge-detection filter system. Using this sensor, low amplitude vibrations have been measured at frequencies of up to 600 Hz. Successful results have been achieved with target reflectivities lower than 5%. When calibrated, the sensor demonstrates satisfactory output for submicron vibration amplitudes. Maximum amplitudes of 1 mm have been measured with an accuracy of 0.2%.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Christine Mignosi, Roger P. Griffiths, Michael Bordovsky, Christopher N. Morgan, Ian H. White, and Nicholas A. J. Lieven "Novel optical vibration sensor using external cavity feedback", Proc. SPIE 3626, Testing, Packaging, Reliability, and Applications of Semiconductor Lasers IV, (14 April 1999);

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