톤버스트 레이저 초음파의 발생과 음향 비선형성

Abstract

Optical System for generating tone burst wave is introduced and the actual waveform is demonstrated. 4 high power pulse lasers were used for exictation and the stablilized Michelson laser interferometer was used as detection. On the other hand, we tired to investigated the nonlinear acoustic effect of generated tone burst laser ultrasonic wave. In thermo-elestic region, the nonlinearity did not appear because the absolute amplitude of ultrasonic wave was so small less than 0.5nm. Whereas, in ablation region, fairly strong nonlinearity appeared because the absolute amplitude of receiving signal was quite large up to about 2nm.