Acoustic microscopy at low frequency

A new design of the acoustic microscopy experimental set up is proposed and analyzed in this paper. The proposed microscope can operate at low frequency (0.1 to 3 MHz) and can be efficiently used in fracture mechanics, structural, and geomechanics applications. In the new design there is no buffer rod and the transducer is proposed to have a shape of a cylindrical shell to produce a line focus beam which is necessary to measure material anisotropy. A line receiver is introduced instead of standard transducer-cum-receiver arrangements. A line receiver can receive only one specularly reflected ray and a few critically reflected rays and thus produces less complicated interference pattern or acoustic material signature (AMS) which is easier to analyze. The shape of the generated AMS depends on the exact location of the receiver strip. Finally, theoretically synthesized AMS of an aluminum plate for different receiver locations are presented.