Laser Scanning Acoustic Microscope Image Signal

Scanning laser acoustic microscope (SLAM) is one type of acoustic microscopy. As a instrument for nondestructive, SLAM is very useful tool to study the internal structure of new materials and new device. The theory of acoustic image is different from the theory of optic image, so the acoustic image is difficult to analysis and identification because of the interference generated by random noise, diffractive streak and acoustic speckle. Base on the conditional SLAM, this paper studied theory of signal quality affected by acoustic wave propagating, acousto-optic interacting, optical path and demodulating. A method for enhancing acoustic image by using magnitude of signal and phase compensating and linear filter and computer digital processing is presented. Examples by using this method and its application in nondestructive for evaluating bond quality of chip lead are provided.