COMPACT PHASE-SHIFTED SAGNAC INTERFEROMETER FOR ULTRASOUND DETECTION

A compact fibre, phase-shifted Sagnac interferometer for ultrasound de tection has been developed. The interferometer is a truly path-matched device, and therefore requires no path stabilization or heterodyning. It is a less expensive and more robust alternative to the heterodyne or path-stabilized Michelson interferometer, The device provides high spatial resolution of ultrasonic detection. It has been used in conjun ction with conventional piezoelectric transducers (PZT) to detect Rayl eigh and Lamb waves and to image a crack in a thin plate, rivet cracks in riveted plates, and for ultrasonic beam profiling. (C) 1998 Elsevi er Science Ltd.