Absolute surface displacement measurement using pulsed photo-electromotive-force laser vibrometer

We demonstrate experimentally a new technique for measuring unambiguously the surface displacement of a vibrating surface using a high sensitivity pulsed laser vibrometer based on the photo-electromotive-force (photo-EMF) sensors. By intentionally introducing a reference vibration with known frequency and amplitude, we show that the photo-EMF pulsed laser vibrometer is able to determine the absolute value of surface displacement independent of the test subject?s surface quality and the amount of laser power density impinging on the sensor.