This paper discusses the latter problem, presenting an ongoing study on the coupling of CAD and ultrasound. Of course, this problem is directly linked with the problem of positioning the probe within the reference system of the object being inspected.

We present first a survey on CAD representations available. Relative merits and drawbacks of various geometry representations are discussed with respect to a ray tracing approach.

The ray tracing method allows a comprehensive representation of reflection and refraction effects and also represents well the focusing lens effect of curved surfaces. It is generally not computationally expensive. Ray-tracing can also be applied for main - beam reconstructions of acquired ultrasonic data, providing a spatial positioning of defect indications with respect to the specimen. We present some results of reconstructions on real geometries, also discussing the recalibration procedure required to ensure that the probe and the geometry are well positioned.

In a second a more prospective step, we present the intermediate results of a development in progress concerning the propagation of ultrasound. Most of the energetic modeling schemes are only able to compute wave transmissions between two materials with simple interfaces like planar or cylindrical interfaces. However, the real shape of the interface geometry is often more complex, and we present our work regarding energetic wave transmission of ultrasound waves between arbitrarily shaped interfaces described by CAD representations.