Focussing the laser turned out to be quite a challenge. When we ordered the laser diode, we presumed it would come focussed. Imagine our disappointment when it was not. Fortunately, we had an old laser diode to cannibalize. Bill Mutch used a razor saw to cut the lens off of it which we then placed over our laser diode at the appropriate distance using medical tubing and electrical tape. The diode still unfocusses when barely touched, but it's better than nothing.

Aiming the diode at the phototransistor is another problem. Because the diode is fairly focussed and the phototransistor is sensitive at particular angles, steady hands are needed to aim at distance. A typical setup involves two staplers (to lean the breadboards against) and lots of tape (to tape them at bizarre angles).

Receiver and Transmitter

2003 Keith Carter, Michael Muccio