PHOTO-ELECTROMOTIVE FORCE CRYSTALS FOR INTERFEROMETRIC MEASUREMENT OFVIBRATIONAL RESPONSE

In this work, results from an interferometric vibration sensing system are discussed. The intrinsic non-steady-state photo-electromotive for ce characteristics of a photoconductive crystal were used practically in a detection system in conjunction with a modified Mach-Zehnder inte rferometer. The system was experimentally verified to provide reproduc ible vibration frequency measurements in the kilohertz region (to mill ihertz sensitivity), with the use of a simple signal-processing approa ch. The system had the added benefit of not requiring external optical components such as optical polarization control, transmission grating s and frequency shifting modulators, and offers information on the dir ection of the vibration motion, unlike many reported schemes.