A small-size multichannel scanning acoustic microscope

A multichannel scanning acoustic microscope, the ultrasonic element of which consists of several focused transducers, is proposed. In this device, images are generated by the electronic switching of the transducers with simultaneous mechanical translation of the acoustic element, thus reducing the data acquisition time. The design of the microscope, the acoustic element of which contains eight transducers with a 100-MHz central frequency, a 6.7-mm focal distance, and a 16° angular aperture, is considered. The multichannel acoustic element and mechanical scanner are physically combined into a remote smadelay linell-size module, enabling studies of large-size complex-shaped objects. As an example, acoustical images of the inner structure of spot welds of aluminum sheets are presented. The comparison of the acoustical images and results of destructive tests has shown that, based on ultrasonic data, it is possible to estimate sizes of weld cores and detect inner defects.