Materials inspection and process control using compensated laser ultrasound evaluation (CLUE): demonstration of a low-cost laser ultrasonic sensor

Abstract

We demonstrate the use of a nonsteady-state photo-induced-emf adaptive photodetector as a robust, low-cost laser ultrasonic sensor. This class of sensor enables high-fractional bandwidth ultrasound detection and, in addition, all-optical compensation of adverse in-factory noise, including vibration, speckle, relative platform motion, and optical fiber modal dispersion. Reference-beam and fiber-based time-delay interferometric configurations were demonstrated, as well as the use of a diode laser as a compact optical probe.