Total Internal Reflection: DVD player

I was interested to find out that the indicator LEDs for the DVD player were actually some way down under the display, soldered to the main circuit board. Light is taken up and along to the front of the display by some solid chunks of clear plastic. The light goes vertically up and then hits the outer slanted edge of the plastic. The angle of incidence will be 45 degrees. If the refractive index is the right size then the critical angle will be lower than 45 degrees so the light will reflect. Angle of reflection will be 45 degrees meaning the light is bent through 90 degrees and exits horizontally. The bigger semi-transparent window is to allow infra-red from the remote control to be detected by the sensor on the circuit board.