A laser harp is an electronic musical instrument consisting of several laser beams to be blocked, in analogy with the plucking of the strings of a harp, in order to produce sounds. The laser harp has been popularized by Jean Michel Jarre, and has been a high profile feature of almost all his concerts since 1981. In recent times, a very similar version has also been used in concerts by British electronic musician Little Boots.
It has subsequently been used in a number of different designs. They have also been used in public art installations such as those created by Jen Lewin on display at Lincoln Center in 2000 and Burning Man 2005 and 2012.
Unframed style, also known as "Infinite Beam" laser harps 
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 somewhat more elaborate than the Framed style, relying on the light being reflected back to a single photodiode. The fan of laser beams is actually a single beam being scanned into a fan pattern. By matching the timing of the reflected beam, it can be determined which of the beams is being blocked and which note needs to be heard. Alternative designs make use of multiple lasers; in these designs, each laser can be independently controlled (pulsed on and off) to simulate playback of prerecorded notes.
In order to generate more control data, such as a continuous range of values like those found in many MIDI controllers, several approaches are available:
- Using an infrared or ultrasonic rangefinder attached to the instrument, such that the position of the hand "plucking the string" is determined.
- Using a laser-based rangefinder to determine the distance from the hand to the laser's starting or ending point (and possibly using this laser itself as the string), a variation on this is using the intensity of the sensor signal itself.
- Using a camera to track the position and motion of the laser dot on the hand, or the length of the exposed beam if visible, then calculating a continuous value based upon a reference.
Other possibilities no doubt exist. Each of these possibilities poses particular challenges and costs, though the first one is relatively inexpensive and straightforward to implement, and can use the same microcontroller which drives the lasers and reads the detectors.
The advantage of using a dedicated sensor mechanism is that the instrument can be self-contained, as opposed to requiring a computer to control it when an ILDA interface and USB camera are used. On the other hand, the PC-based approach offers more flexibility and can be constructed using mostly off-the-shelf hardware.
Unframed laser harps benefit from the use of higher-power lasers, as they facilitate easier detection by the sensor system. As the sensor is exposed to all ambient light, it can get swamped out by stage lighting behind the artist if the sensitivity is too high. To avoid this problem, ambient light sensors can be used to reject ambient light from the laser light sensors. The use of (white or light-coloured) gloves improves the instrument's performance by allowing more light to scatter off the player's hands and therefore provide the sensor with a higher signal-to-noise ratio with respect to ambient light. Furthermore, the gloves protect the player's skin from potentially hazardous laser radiation and give audiences a more visual impression of the instrument being played.
Bi-color and full color laser harps 
In 2005 the first free full color ILDA laser harp controller idea and project was born on laserist board and the harpelaser.com was registered. The last sensor designed rejects ambiant light and can measure the hand height in the beams. It offer the possibility to play on the sound like the pitch, filters. these things was not really available before.
In 2008 Maurizio Carelli, an Italian software and electronic engineer, had the idea of a new portable red/green laser harp: This device features a configurable full octave with green beams for any diatonic note and red ones for any chromatic note for full Diatonic and Chromatic scale. In this way any musician can easily play a laser harp, fully polyphonic. This machine became the first portable bicolor laser harp, and it is still in production. In the second half of 2010, he also designed a ILDA full color laser harp controller.
In January 2011 the world's first full color laser harp controller for ILDA compatible laser projectors  was commercially introduced: the Prolight Laser Harp Controller LH1 This is a fully plug-and-play compatible, daily light independent, polyphonic Laser Harp Controller which can work with any type of ILDA compliant laser projector, turning it into laser harp. Users can switch between several modes with different number of beams as well as several beam color combinations including full color rainbow mode, bi-color, and single color combinations. The Prolight Laser Harp Controller's design does not include a built-in laser projector, which enables the users to freely choose their own laser setup for every performance, whether they need a less powerful laser projector for indoor events or a high-powered laser for open air performances. It can be used with monochrome lasers or full color lasers as well.
Unframed style, "Image recognition" laser harp 
The image recognition laser harp is also an unframed design, but uses a high-speed USB camera connected to a laptop computer, instead of a photodiode to detect the reflected light from the hand breaking the beam. The digital picture is analyzed by the computer software to determine which beam is broken and send the appropriate MIDI signal back to the synthesizer, which is responsible for creating the sound. The computer also controls the laser projector via an ILDA USB laser controller.
Framed style 
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 1975/6 was an octagonal shape with a 5 X 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 of Laser Harp can be created in any size, from a lap sized harp to a room sized installation, or larger, like the installations seen at Burning Man. In this design, only an analog DC (on/off) 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 analyzer/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.
Typical framed style laser harp software functions 
- Trigger Mode — In this mode, breaking a beam always triggers the event, sound (a sample, loop or MIDI note), image or video that that particular beam has been preset to trigger. Each beam will always trigger its own preset event when broken. e.g. If the beam number one is set to play a bass drum and beam two a snare drum; then one will always play a bass drum and two a snare.
- Sequence Mode — In this mode, breaking any of the beams plays a preset melody or song one note at a time. Familiar tunes may be played by the breaking the beams in time with the song. Little or no musical ability is required to play a tune. Similarly, a sequence of images could be displayed or an image could be built up one part at a time.
- Event Mode — When broken, a beam set to 'Event Mode' can change octaves, sounds, songs or programmed settings for any or all of the beams.
- On-Off — A sound will play only while a beam remains broken. The sound stops when the beam is unbroken.
- Play to end — Once triggered, a sound will play to the end regardless of when the beam is unbroken.
- Toggle Mode — Breaking a beam the first time triggers a sound which plays to the end (or loops) until the beam is broken a second time.
All beams do not have to be set to the same Play or Switch Mode - each beam may be set up differently.
Safety considerations 
In order to produce laser beams visible in normal air, a relatively powerful laser is needed; at least about 20 mW of power, depending on the type of laser and the design of the instrument, is required in order to produce a visible array of beams. However, a considerably more powerful laser is needed to yield spectacular results, generally 500 mW or more. In any case, class IIIb or IV lasers will usually be necessary, introducing a significant risk of skin and eye damage unless precautions (gloves and protective glasses) are taken.
Use in Jean-Michel Jarre concerts 
The laser harp is one of the most famous instruments used by Jean Michel Jarre in his concerts. The instrument is used in almost every concert with the exception of Aero and the Oxygene 30th Anniversary Tour. It is almost always used in the third part of Second Rendez-Vous, but has also been used for tracks including Third Rendez-Vous, Chronologie 3, Calypso 2, and Oxygene 7. The characteristic sound of the laser harp in Jarre's performances is generated by a factory preset on the Elka Synthex synthesizer.
The first laser harp that Jarre used for The Concerts In China tour, has been made by Denis Carnus, a french engineer living in South Of France who has been working a lot with Bernard Szajner. On the LP the track was simply titled Laser Harp (or Harpe Laser in its original French).
A different laser-harp have been used by JM Jarre in the Houston, Lyon, and London concerts: this one was built by Philippe Guerre.
The laser harp for the Defense concert has been built by Claude Lifante.
After that, JM Jarre used a laser-harp built by Yan Terrien for the software and Philippe Langet for the hardware. This harp has been used by JM Jarre during fifteen years, supported by two technicians: Denis Benoit ans Laurent de La Casinière.
Some people suspect the laser harp, as well as some other custom instruments, is a fake; careful inspection of concert footage of Jarre playing the harp occasionally indicates that striking the same beam produces different notes, suggesting that the harp is simply designed to trigger the next correct note irrespective of which beam is broken. However, this method is unreliable, as videos are invariably edited before release. As an example, in the live recording of the Paris La Défense concert as broadcast on the Europe 2 radio station, it can be clearly heard that the laser harp is malfunctioning, and in fact after a while gets replaced by a different synthesizer. In the video release, no trace is left of this malfunction. Also the harp is fitted with foot pedals for selecting scales, making it quite plausible that the same beam can trigger different notes.
During Jarre's 2009 In-doors Arena Tour, he commented on his blog that he "should make a few intentional mistakes for people to really understand that it is live". Later the same day, at a concert in Helsinki, the harp "suddenly froze in Rendez Vous 2 for unknown reasons".
Two people claim to be the inventor of the laser harp: Geoffrey Rose and Bernard Szajner. Geoffrey Rose took out a provisional patent with the British Patent office in 1975/6. Bernard Szajner has a Patent (it means that the Office Patent of Paris never found evidence of another inventor of the same/similar instrument before him). (Patent: FR2502823 (A1) Date de priorité : 1981-03-27).
The engineers that have created a laser harp for jean Michel Jarre are: Denis Carnus, Philippe Guerre, Claude Lifante, Yan Terrien.
Several amateur electronics enthusiasts have created their own versions of the laser harp: Steve Hobley, Manuel Schulz, Franck Morisseau, Albert de Jonge, Maurizio Carelli, Sébastien Pamart, Andrew Kilpatrick, Sébastien Gally,.
See also 
- "Burning Man 2012 Honorarium Art Projects".
- "Jen Lewin Studio Art Exhibits".
- "free ILDA laser harp controller".
- "Hand height sensing".
- "Kromalaser: Laser Harps".
- Maurizio Carelli (2010-01-18). ""Kromalaser Hymn" played with Bi-Color Laser Harp". Retrieved 2010-03-07.
- "Prolight laser harp controller".
- JMPSynth (2009-04-01). "Elka Synthex Sounds". Retrieved 2009-04-01.
- Wavebox2011 (2011-02-27). "Elka Synthex Laser Harp". Retrieved 2011-02-27.
- Jean Michel Jarre (2009-05-16). "Scandinavian ellipsis". Retrieved 2009-05-25.
- Jean Michel Jarre (2009-05-17). "Flash back". Retrieved 2009-05-25.
- Jean Michel Jarre (2009-05-26). "Freezing laserharp @1:08".
- "Laser Harp Patented by Bernard Szajner". Laser Harp Patent - Patent Office of Paris. Retrieved 14 September 2011.
- "Harpe laser".
- "Bi-color Laser Harp".
- Video S.Gally (lien youtube)
- Site S.Gally (Site)
The Laser Harp used for the Destination Docklands London concerts by Jean Michel Jarre in October 1988 was designed and built by Laserpoint, a Cambridge, UK, laser display company. Later re-used with a single 4 watt argon ion laser at the musician's Paris retrospective, Concert D'images the following year, the device was originally built as a 14 string polyphonic instrument using three 20 watt argon ion lasers mounted on a custom built optical frame. The 3 beams of light were then split into 5, 5 and 4 beams each on beamsplitters that deflected the light upwards in front of the musician and on into the night sky. 14 mechanical collimators, made out of 200 mm long 10 mm diameter aluminium tubes and mounted parallel to each laser beam, each had a photocell at their base. As the musician interrupted the beam of laser light that was rising parallel to a particular collimator, the precise wavelengths of light present in the beam (principally 488 and 514.5 nanometres) were then picked up by the photocell when they were reflected down the tube of each collimator. The lengths of the tubes prevented cross-talk between each beam reflection. Optical filters in the base of each collimator took out other wavelengths from stage lighting to send a clear signal of which note was being played to the processing electronics that were linked to the musician's string synthesiser. The musician could increase the volume of a particular note by moving his hand down closer to the beam source, thus increasing the amount of laser light hitting the photocell below. As the system worked by reflecting the light downwards diffusely when each beam was interrupted without any detectors mounted above, the high power beams were visible for hundreds of feet into the air when left unplayed. The whole assembly was mounted below the stage with only the beams emerging to be played at the appropriate time. Photographs of the equipment on test in Cambridge UK before the concert are available.