Patent ID: 7474411
Filing Date: 2009-01-06
Classification: G01H

Abstract:
1. A method for generating and detecting ultrasonic surface displacements on a remote target comprising: generating ultrasonic surface displacements at a surface of the remote target; generating a detection laser beam; optically filtering the detection laser beam, the optical filtering providing at least one of amplitude noise filtration or phase noise filtration; directing the detection laser beam to the surface of the target to produce light phase modulated by the ultrasonic displacements; collecting the phase modulated light; processing the phase modulated light to obtain data representative of the ultrasonic surface displacements at the surface; and obtaining data representative of the ultrasonic surface displacements at the surface of the remote target responsive to the processing, wherein optically filtering the detection laser beam comprises passing the detection laser beam through an optical resonant cavity with high finesse, and wherein the optical resonant cavity with high finesse comprises a Sagnac cavity.