This is the sensor that looks straight up into the beam. There is three sensors for each channel, one straight up into the beam, one on the side, angeled so it can only see the bottom part of the beam. This so I can play low octave with the hand placed low, and high octave with the hand placed high. The third sensor is the one in the previous picture, sensing “touch” for key changing.
neo-norwegian experiments in art and technology 
