A portable laser vibrometer is described which allows the engineer to simply point a laser beam at a target surface in order to obtain a measure of its vibrational velocity level in amplitude and phase. This non-contacting transducer will complement the accelerometer in situations where use of the latter is precluded: i.e., hot, light or rotating surfaces. The instrument is compact, portable, robust, user friendly, inexpensive and is safe for general on-site use. An investigation of the mechanisms which determine the noise floor is presented and minimization procedures are defined. The first prototype constructed has a dynamic range of 60 dB and a frequency response of 20 kHz, which is adequate for general use. Two applications of use on rotating and lightweight surfaces are reported.
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