This is an interactive Java simulation on the phenomenon known as "beam-splitting".  A virtual  beam of incident light is passed through two wedge prisms, which deflect light by refraction rather than reflection.  Users control the wedge orientation to "steer" the beam up and down on the screen.

This is an interactive Java tutorial that explores how refractive index values are related to the angle of refraction in monochromatic light passing from one medium to another.