An acoustic microscope with a cylindrical lens and ultrasound transducer have been considered, as well as the method based on it for the measuring of longitudinal and transverse wave velocities, the thickness and density of the investigated layer. A theoretical model of the microscope has been constructed, and the relation between the spatiotemporal output signal of the transducer and the angular dependence of the sample reflection coefficient has been found. It has been shown that the velocities of body waves and the thickness can be determined by the delays of ultrasound responses reflected from the layer boundaries measured by the transducer elements, and the density, by the amplitudes of these responses. The method was tested experimentally using a 20-element transducer with a central frequency of 15 MHz and a period of 0.8 mm. The example of a duralumin plate has shown that the error in measuring the thickness and velocity of longitudinal waves error does not exceed 1%; the velocity of transverse waves, 2%; and the density can be estimated with an accuracy of about 5%.

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.

We suggest a new method for measuring local values of the velocity and attenuation of leaky acoustic waves, which is based on wave field measurements using an immobile array of receiving ultrasonic transducers. In comparison to the methods using a single focused transducer mechanically scanned over a given region of the sample, the proposed technique is advantageous in having a higher operation speed due to the electronic switching of receiving channels in the array and in requiring no high-precision mechanical scanners. A ray model of the proposed measuring system comprising an array of ultrasonic transducers with an electronic scanning facility is described. Theoretical conclusions have been experimentally confirmed by tests on the samples with known properties.