The end planes

The ends of the FOC play a central role, especially the end planes. The optical contact to the LED diode or photodiode is made at these surfaces. Therefore they must be absolutely clean, smooth and vertical. This type of surface finish can only be achieved with special cutting tools. A FOC should never be cut with tools for electric wires (such as wire cutters).

The FOC must only be cut with special tools!

An imperfect optical contact surface causes large optical loss.