High temperature applications of laser interferometry

Many industrial processes require non-contact sensors for various reasons, including high temperature, moving parts, hostile environment (viz. nuclear radiation, high power laser radiation, etc.) or simply the necessity for remoteness. This paper presents a review of our recent research and development on the measurement of displacement by four laser optical methods. These are: (1a) a point displacement method at 30 Hz, (1b) a microscopic laser speckle interferometry at 250 frames/s, (2) a shearographic fringe imager in the kHz frequency range, (3) a Fabry-Perot speckle interferometer for measurement of relative displacement amplitude also in the low MHz range. Each of the methods is presented in the context of an industrial application.