A laser Doppler vibrometer (LDV) is a scientific instrument that is used for non-contact vibration measurement of vibrating surfaces. The laser beam generated by the LDV is directed onto the surface to be measured. The amplitude and frequency can be calculated from the Doppler shift of the laser beam (by movement of the surface). The output signal of an LDV is usually a continuous analog voltage that is directly proportional to the vibration velocity of the vibrating surface.
The non-contact measurement is a major advantage of a LDV compared to other methods such as acceleration sensors. Thus, surfaces that are inaccessible or that are too small or too hot may, in order to mount a conventional sensor can be measured. Furthermore using a LDV the measurement object is not modified by an additional mass, which may be essential especially for small targets.