Laser harp

A laser harp is an electronic musical user interface and laser lighting display. It projects several laser beams—and a musician plays these by blocking them to produce sounds-reminiscent of a harp. The laser harp has been popularized by Jean Michel Jarre, and has been a high profile feature of almost all his concerts since 1981. British electronic musician Little Boots has used a similar instrument in concerts. The British electro jazz band 1201-Alarm feature a laser harp as a main aspect of their live show.

Laser harps have appeared in a number of designs. They have also been used in public art installations, such as those by Jen Lewin at the Lincoln Center in 2000 and at Burning Man in 2005 and 2012, as well as those created by Johnny Dwork at the Harmony Festival in 2011, at the Portland Art Museum in 2012, at The Tech Museum of Innovation in 2014, and at the Oregon Museum of Science and Industry in 2015.

This style of laser harp is generally built using a single laser, splitting its beam into an array of beams in parallel or fan arrangement. Playing the actual sound is usually handled by connecting the laser harp to a synthesizer, sampler or computer.

This frameless design is more elaborate than the framed style, relying on reflecting the light back to a single photodiode. The fan of laser beams is actually a single beam scanned into a fan pattern. By matching the timing of the reflected beam, the instrument can determine which beam the player is blocking and sound the corresponding note. Alternative designs use multiple lasers. In these designs, each laser can be independently controlled (pulsed on and off) to simulate playback of prerecorded notes.

...
Wikipedia