Meaning
Non-contact measurement technique that uses the frequency shift of reflected light to determine the velocity of a vibrating surface. Laser doppler vibrometry enables the precise tracking of mechanical oscillations without adding mass to the target, which is essential for lightweight or delicate components. The system operates by splitting a laser beam into a reference path and a measurement path that hits the moving object.
When the two beams recombine, the resulting interference pattern reveals the instantaneous velocity and displacement of the surface.
Optical Setup
A specialized sensor head contains the laser source and the detectors needed to capture the backscattered light. Using laser doppler vibrometry allows engineers to scan large areas or focus on a single point to build a detailed vibration map. This method is particularly useful for measuring high-frequency modes that are difficult to capture with physical sensors.
Remote detection is the standard.
Measurement Capability
The system can detect motions at the picometer scale across a wide range of frequencies. Laser doppler vibrometry provides a more accurate view of the tool tip behavior than can be achieved by placing accelerometers on the spindle housing. It is a preferred method for validating finite element models during the transition from prototype to production.
Data Integrity
Accuracy depends on the surface reflectivity and the alignment of the laser beam relative to the direction of motion. In dusty or oily manufacturing environments, the signal quality of laser doppler vibrometry can be compromised by airborne particles. Technicians must use reflective tape or specialized coatings to ensure a strong return signal from dark or transparent materials.
Despite these requirements, the ability to measure without physical contact makes this the standard for high-performance dynamic analysis.
