Vibrometer-Universität

Fundamentals

Laser Doppler vibrometry (LDV) is a non-contact vibration measurement technique using the Doppler effect. The LDV permits measurement of hot, miniature or soft surfaces, even under water, without mass-loading. Polytec vibrometers are eye-safe class 2 laser instruments use a low power Helium-Neon laser and can operate at distances of hundreds of meters.

Laser vibrometers are typically two-beam interferometric devices which detect the phase difference between an internal reference and the measurement beam. The measurement beam is focused on the the target and scattered back to the interferometer. The heterodyne principle used in Polytec vibrometers generates an FM carrier to provide the directional information, and also opens the possibility to digital traceable vibrometry.

Polytec's many years experience have brought about a range of special-applications laser vibrometers for use on rotating surfaces, at very high speeds (30 m/s) and at very high frequencies (30 MHz). Polytec vibrometers measure not only velocity, but also direct displacement.