Vibrometer University

Getting the most out of a laser vibrometer is made easier by understanding the physics behind the instrumentation and the fundamentals that determine its range of application.

Fundamentals

Laser Doppler vibrometry (LDV) is a non-contact vibration measurement technique using the Doppler effect. LDV permits the 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 that detect the phase difference between an internal reference and the measurement beam. The measurement beam is focused on 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 of digital traceable vibrometry.

Polytec's many years of 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.