You might want to take a look at this tutorial, not true refraction, but it might give you some ideas:
http://library.creativecow.net/articles/james_colin/glass.php
Johnny Cuevas, Editor
Thinkck.com
"I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work."
---THOMAS EDISON on inventing the light bulb.