A laser harp is an electronic musical user interface and laser lighting display. It projects several laser beams played by the musician by blocking them to produce sounds, visually reminiscent of a harp. It was popularised by Jean-Michel Jarre, and has been a high-profile feature of almost all his concerts since 1981.

French composer Bernard Szajner applied to patent the laser harp in 1981. It was granted in 1982, meaning that the French patent office had found no evidence of another inventor of the same or similar instrument before him.

However, Australian inventor Geoffrey Rose claims to have taken out a provisional patent with the United Kingdom's patent office in 1975–1976, and his invention may have been shown and used as early as 1976.

The framed style, which is often created to look like a harp with strings, uses an array of photodiodes or photoresistors inside the upper or lower part of the frame to detect blocking of the laser beams. The framed harp built by Geoffrey Rose in 1975–1976 was an octagonal shape with a 5×5 matrix of laser beams. The lasers can be mounted on the 'neck' or upper side of the harp, shining down, or on the body, shining up. Typically, the lasers used are very low-powered 5 mW red or green lasers, which are considered safe for public interaction by the FDA. Any number of laser beams can be arranged in this type of laser harp, from as few as one or two, up to 32 or more, depending on the capacity of the MIDI controller(s) and software being used. This style can be built in any size, from a lap-sized harp to a room-sized installation, or larger. In this design, only an analog trigger is created by the breaking of the beam (and the DC circuit made by the beam shining on the optic sensor), which is sufficient to trigger any number of events (musical or otherwise) as determined by the data analyser or software in question. In the MIDI controller, this analog DC current interruption is converted to a digital signal, which is then used to trigger many possible events or actions. Some software comes equipped with full wave file editors and synthesizers, and can also trigger video and still imagery via projection units.

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.^{[clarification needed]}

Several techniques generate more control data, such as a continuous range of values like those in typical MIDI controllers:

The first of these is relatively inexpensive and straightforward to implement, and can use the same micro-controller that drives the lasers and reads the detectors.