Measurements of Flow Velocity and Temperature Using Laser Photothermal Effect with a Multiple Beam Interferometer

This paper describes measurements of flow velocity and temperature using photothermal effect. We developed a multiple beam interferometer for detecting small phase variation caused by photo-thermal effect. The operating point is set on the maximum inclination of fringe intensity curve by the use of lead zircorate titanate (PIT) piezoelectric ceramics. The influence of the walk off effect on phase measurement is eliminated by the use of laser beam of small diameter. Using jet of air mixed with ethylene gas, it is demonstrated that this method is a useful tool to measure flow velocity and temperature. (Author)