You might want to check out [url=]Ray tracing (polygon: range from 3-32 faces)[/url]

You will find total internal reflection if you re-arrange the sgape of the prism.
(e.g. check out attachement).

There is another similar applet,too!
[url=] Prsim optics (slow motion of light entering a prism)[/url]

Let me know in more detail if both the above two simulations do not work for your need!