Arduino based midi instrument
The laser harp is an electronic instrument, unlike a traditional harp with metal strings this harp has strings of light. It also does not have a frame: its laser strings stretch out infinitely into space.
Each beam represents a MIDI note. As your hand cuts a beam, the note is played.
Since this harp has no frame, identifying which beam was cut without the use of expensive technologies like Web cams or Kinects becomes an interesting problem as you can’t simply place a sensor array at the ends of the beams.
How the beams are created:
A laser beam is directed to a mirror on the motor. With every step the motor takes, the position of the mirror changes, deflecting the beam in a different direction every time. The steps take place fast enough for the beams to appear as if they are simultaneously present.
How the harp knows which beam has been cut:
Every beam has a corresponding motor position. When a beam is cut, the sensor detects an increase in light intensity. The Arduino then looks for the position of the motor at that instant, and thus identifies the beam in question.