Measuring speed of moving surface by laser beam - superimposing scattered, Doppler-shifted light unshifted light and measuring resulting beat frequency

摘要

Measuring the speed of a moving surface involves directing a measurement light beam emitted by a laser towards the surface and superimposing the Doppler shifted scattered light and the unshifted light to produce a beat whose frequency is a measure of the surface's speed. The scattered light is fed back to the laser for optical amplification and the resulting beat in the laser's output light is evaluated. ADVANTAGE - Continuous reliable measurement at low equipment cost.