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APPLICATIONS ABSTRACTS:

VMS APP-1: Laser vibrometer using photoelectromotive-force sensors

We demonstrate experimentally significant improvement in the sensitivity of photoelectromotive-force ~photo-EMF! laser vibrometers. The vibrating surface is discretely sampled by individual laser pulses and recorded by the photo-EMF sensor via the generation of photocurrent pulses whose magnitudes are proportional to the instantaneous surface displacements. With a sufficiently high sampling rate, reconstruction of the vibration wave form can be achieved by conducting envelope ~or peak! detection of the resultant series of photocurrent pulses. Significantly higher peak optical power levels of the probe laser pulses, which can be orders of magnitude greater than those of continuous-wave interrogation lasers with the same average power, lead to proportional enhancement in the photo-EMF response and remarkable improvement in detection sensitivity when the photodetection process is initially amplifier noise current limited. © 2003 American Institute of Physics.