Multi-Point Vibrometry (MPV) for Aerospace Structural Study

Technology Description

• Multi-Point Vibrometer extends the capability of a single-point Laser Doppler vibrometer to simultaneously measure the temporal vibration of an array of measurement points. MPV utilizes Diffractive Optical Elements to generate uniform arrays of illuminating beams to the surface of the vibrating measurement target.

Applicability:

• Detects impacts or other sources of impulse loading
• Measures material fracture - crack growth or identification
• Determines global vibration suppression for structural acoustic control

Benefits:

• Simultaneous time history of the vibration from multiple points of a measurement surface to provide interaction and correlation information among those points.
• Capture unsteady, transient vibrations
• Validation of theoretical and simulation prediction

Recent Results:

(L) The MPV signal from a single point when there is no vibration on the plate. The frequency of this waveform can be adjusted as the difference between the setting shift frequencies of the two Bragg cells.

(R) A modulated waveform as a vibration is introduced to the plate.

The generated dot array spots on the vibrating plate. Here the spots image (D=2mm) looks larger due to the auto-focus effect of the digital camera.

Using Phase Lock Loop technique the demodulation process retrieves the modulating signal