http://www.phy.ntnu.edu.tw/ntnujava/simulationBuilder/ Optics applet: A Physlet powerful java optics applet by Wolfgang Christian.  
One of the best applets i know, attachment can be downloaded to run as standalone.
Awesome & Complex. Can this be made in Ejs?



Physlets®, i.e., the Java applets themselves, are a registered trademark of Wolfgang Christian.  

found it here too http://webphysics.davidson.edu/Applets/optics4/default.html
but the view is small.