This WidgeNDT is a tool allowing to apply the Snell / Descartes’ laws for propagation through a plane interface between two media, and thus visualize a ray tracing for a particular propagation mode, with the refracted angle expected by the user.


Launch the WidgeNDT (requires Java to run)


Multiple options and parameters are offered through pointers, making this tool fully interactive. For example, you can adjust the propagation velocity in each medium, and select a desired refraction angle for a specific mode (L or T). The tool will display the required incidence angle according to the Snell / Descartes’ laws.

The incident propagation medium can be either a semi infinite plane, corresponding to an immersied probe configuration, or limited to a coupling wedge between the transducer and the specimen, describing a contact probe configuration.

In the case of an immersed probe, it is assumed that the coupling medium is water at a certain temperature adjustable through a pointer. The waves’ velocity in water is then modified by any change of this temperature

In the case of a contact probe, you can adjust the velocity in the wedge using a speed cursor.

The transducer length, the sound path in the incident medium, the dimensions and position of the probe wedge are adjustable either through the parameters pointers, or by dragging the blue dots with the mouse

Beyond this interactive calculator for Snell / Descartes’ laws, you can choose to simply represent a central ray from the center of the transducer, or to switch to “beam” mode, or to consider a plane or focused crystal. Let the choices offered guide you to build a realistic configuration.

Finally, you can see a marker at a given propagation time, along the paths corresponding to the L and T propagation modes. Then, you can visualize on the different paths an acquisition time gate, defined by a start time and a duration.

The video below illustrates how this WidgeNDT works:

Feel free to play with this tool, inform people around you of its existence, and share with us your comments and critics!