Passive Optical Technique to Measure Physical Properties of a Vibrating Surface.

摘要

We report on a passive imaging technique to measure physical properties of a vibrating surface using the detection of optical signal modulation in light scattered from that surface. The optical signal modulation arises from a changing surface normal and may be used to produce a surface normal change image without touching the surface and changing its state. The images may be used to extract the surface vibration frequency and mode pattern which are dependent on surface properties of the material, including its flexural modulus and mass density. Comparison of the vibration image with a finite element model may be used to infer properties of the vibrating surface, including boundary conditions. A temporal sequence of optical images of signal modulation may be analyzed to infer spatial damping properties of the surface material. Damping is a measure of energy dissipation within the material. The approach being developed has the advantage of being able to remotely image arbitrary sized structures to determine global or local vibrational properties.