Measurement of ultrasonic displacement vector with an F-P interferometer

Abstract

The laser interferometer technique for receiving ultrasound has potential for a wide range of noncontact ultrasonic measurements and has therefore received considerable interest in recent years. Several interferometric methods for detecting the normal displacement components of ultrasound have been developed and applied to nondestructive evaluation for material characterization. In order to study the propagation of ultrasound in a medium and to characterize materials more accurately, detecting both normal and tangent components of ultrasonic displacement simultaneously is necessary. Therefore, an F-P interferometer, which receives scattering lights at scattering angles +θ and −θ from sample surfaces and measures the ultrasonic displacement vector simultaneously, is introduced in this paper. In order to increase the scattering light intensity and determine the scattering angle θ precisely, a new method for modification of a sample surface is introduced and some experiments are presented in this paper.