Laser Doppler Vibrometry

Laser Doppler Vibrometer (LDV) is a Laser based non-contact vibration measurement system. It consists of three measuring scan heads which are capable of measuring the movements in all the three orthogonal directions yielding full information of the three dimensional movements [Figure 36.1]. The system works on the principle of Doppler Effect and interferometry for vibration measurement.

Figure 36.1 Laser Doppler Vibrometer with composite test plate

The minimum detectable vibration speed using this system is 5 µm/s at1Hz resolution while the maximum speed is of 10 m/s. The LDV system software controls the entire measurement process with graphical user interface. The PSV system also has the provision for input channels which can be used for simultaneous acquisition of data from accelerometers, load cells etc. Transfer function between any of the input channels connected to the system can be obtained. Signal generator card (NI-671x) contained in the system is used for generating excitation signals in the frequency range of 0-80 kHz. LDVs can measure vibrations up to 30 MHz range with very linear phase response and high accuracy. Applications of LDV include modal analysis of automotive parts, car bodies and aircraft panels etc.