Typical normal incidence immersion testing is used to generate longitudinal waves in the sample. For focused immersion transducers, additional wave types may be generated because the curvature of the transducer face results in ray paths that are oblique to the sample surface. These obliquely incident rays generate a longitudinal and a shear wave within the sample. Depending on the thickness of the sample, the shear waves may reflect from the back surface and can be resolved in standard A-scan measurements. This presentation will outline the experimental parameters needed to generate and optimize the detection of these secondary shear waves. Next, several applications will be discussed using these secondary reflections including measurements of shear wave speed and attenuation. Furthermore, these secondary waves are anticipated to lead to improved defect detection techniques, especially for geometries of defects that may not be sensitive to normal longitudinal waves or other inspection methods.

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