In this paper, a similar system described by Shan Q. et al(Shan Q.,Jaw
ad S.M. and Dewhurst R.J. Ultrasonics,1993,31,105-115) is presented. A
s an improvement to their system, a personal computer was used to prov
ide the fast execution speed of the stabilization algorithm. With this
system, a through transmission ultrasonic pulse was captured by a sma
ll 5mW He-Ne laser.