Laser velocimetry of moving object surface layers in plasma processing - using vibrating mirror whose reflection is correlated with that from object mirror, for evaluation of speed-dependent Doppler shift

摘要

The beam (5) from the laser (8) passes through a Faraday rotator (12) and beam-splitter (13) and is reflected (14) from a mirror (6) of dia. about 5mm fixed to the moving object (3). Part (15) of the outgoing beam (7) is reflected (17) from the vibrating mirror (16). The beam (14) returned from the object mirror (6) is deflected to a detector (9) where it is superimposed on the other reflection (17). The vibrator (18) is driven (27) by the main oscillator (26). USE/ADVANTAGE - Also for measurements of vibrating machine parts, or vehicles during prodn. Exact measurement w.r.t all three translational and three rotational axes with higher spatial and temporal resolution is possible over wide range of speeds.