An optical real-time, noncontact vibration measurement technique

Presented in this work is an optical real-time, noncontact vibration measurement technique that measures vibration amplitudes above the shadow moire range (greater than 0.1 mm).

An experimental technique was devised whereby vibration amplitude measurement can be made using the modulation of reflected light from a vibrating object. A direct calibration was made for ekact object displacement to detector voltage reading. By using this method the first three mode shapes of a cantilever beam were traced.

The primary conclusion of this study is that the technique is a practical vibration measurement tool with a measurement range extending from 0.1 mm to at least 10 mm.