A quantitative acoustic microscope with multiple detection modes

An acoustic microscope that permits operation with both toneburst and impulse excitation of the lens is presented. Either mode can be selected and combined with mechanical scanning in any direction. In the impulse-excited mode, the specular and Rayleigh signals from the sample are resolved in time, and analysis is performed to obtain surface wave propagation parameters. The power of the simultaneous application of these techniques is illustrated by measurements on specimens of intact and fractured glass and duraluminum. Reflection and transmission coefficients for a crack are measured, and conclusions are drawn about V(z) processing. These results are significant because the images of cracks produced by the conventional toneburst scanning acoustic microphone (SAM) tend to be complex. Diffraction from the tips of cracks is observed in the microscope.