Laser Wiki

Waveplates, demystified - Simple-version (..scroll down the page a bit for the info / diag's..) [http://www.redoptronics.com/waveplate.html Red Optronics](Note: Commercial external-link- No 'endorsement' implied; for Informational-purposes only..)]

..Gory-version.. :p [http://en.wikipedia.org/wiki/Waveplate External Wikipedia-article on Waveplates]

..also, found this, too: [http://optics.byu.edu/animation/polarwav.mov Simple but informative Waveplate-principles animation w/ voice-over]