Laser Doppler velocimetry using the photoacoustic effect of RF-excited CO_2 laser

摘要

A new laser Doppler velocimeter employing an RF-excited CO_2 laser has been developed by using its photoacoustic effect. A change in the pressure of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, is employed to detect the Doppler frequency shift. We found that a Doppler frequency shift as small as 50 kHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.