LaserWeb
The LaserWeb is a device that senses the breaking of beams of light. Up to eight laser pointers are mounted so that their beams travel across the stage or from the ceiling to the floor. Each beam is focused on a small box, placed some distance away, containing a light sensitive sensor. All of these receivers are connected to a small box containing a single-chip microcomputer, which generates a MIDI message when one of the beams is interrupted. This MIDI message indicates both which beam was interrupted, and the velocity with which it was broken.

You can imagine the LaserWeb as a giant harp whose strings travel across the stage. When a performer breaks a beam, it is like plucking one of the strings. Except that this instrument is not limited to producing music, but can instead (in conjunction with a software program like Interactor LPT) control a variety of media devices.

The LaserWeb is used to great effect in one section of The Chemical Wedding of Christian Rosenkreutz. Each time the dancer breaks the beam, a light becomes suddenly bright and then fades out while the musical score simultaneously intensifies and then softens. A video clip of this section can be seen here.
MidiDancer | PIezo Sensors | Wireless Cameras | Software