Laser Ultrasound Source for NDE Applications: Calibration in a Liquid

Abstract

The laser ultrasound source emerges when radiation is absorbed by a body. At a small energy deposit the linear thermoacoustical effect dominates in the process of sound generation. At higher energy deposits the conversion from optical to acoustic energy happens via various channels. We present calibration studies of laser ultrasound source for the media with non-zero optical penetration depths. It is known that models of laser generation of ultrasound taking into account optical penetration depth proved to be useful tools for NDE applications. There is a necessity to implement so-called “buried ultrasound sources”. Also, there is a growing interest in laser ultrasound testing of non-metals [1]. Liquid solutions can serve as testing media to predict the influence of the optical penetration depth upon the fine structure and the magnitude statistics as well of the acoustic signal. Calibrating measurements of laser-induced stress waves help to reveal some new mechanisms of optoacoustic (OA) conversion.