## Wave-Chain

The dispersion curves of the two parts of this wave chain share a common and a distinct frequency range. In consequence, low frequency waves generated in the left part cannot enter into the right part and vice versa. I find it very nice to be able to visually observe the obvious difference between phase and group velocity, forbidden frequency ranges, evanescent wave .... Download the movie and run it continuously.

## Helmholtzcoil/Short cylindrical Coil

The field lines of these coils have been generated using the so called FLIC/DLIC-algorithm (fast/dynamic line integral convolution, J. Belcher). At MIT, the software, developed and published by J. Belcher and his group, is used for example in the teaching of electromagnetism. In order to adapt the software to the specific needs of our students, I have ported the Java software to LabVIEW. Such pictures should help students "see" the magnetic and electric fields instead of only remembering formulas and numbers.

The field line plots were then introduced as texture into 3D-models, built with Cheetah3D, a modelling, rendering and animation program for Mac OS X.

## Refractive Index Ellipsoid of an uniaxial Crystal

(for example LiNbO3)

## Biaxial Crystals

Through the application of a voltage, the index ellipsoid of LiNbO3 becomes biaxial. Focusing white light through the crystal between crossed polarizers, beautiful interference colors can be observed .......