Jean Michel Jarre’s Laser Harp

Jarre’s Laser Harp by Bernard Szajner / Denis Carnus / Claude Lifante used for the China Concerts

The first laser harp was invented in April 1981. The idea came out of the brain of Bernard Szajner. To learn more about the first laser harp, please refer to the “Laser Harp by Bernard Szajner” section. The China-Concerts harp is based on the one by Bernard. I have recieved many questions about the confusing picture on the China Concerts Sleeve (see picture).

Here is Bernards analysis:

“I see two pieces of metal forming a triangle, opposite of mine as the narrow angle points upwards in this one. I also see what SEEMS to be a double emission of laser beams, probably two 5w beams from two lasers or two beams from a single 15w with a beam splitter.”

“But it could also be a single 15w beam and a single grating. It does look like more than 5w. Each beams seems to go through a diffraction grating. By the way, I really don’t remember any more but I vaguely think that my gratings were 1500 lines per inch or 3000… To get back to the picture, I am under the impression that the diffracted beams run close to the metal structure so I guess that where each beam passes close to the metal, there is a small beam splitter which lets the beam go forward in the air but also reflects part of the light in the direction of a light sensor. However, normally, we should see an impact in shape of a luminous dot on the beams splitters if such is the case and with this picture, I cannot see anything like that…”

Laser Harp by Yan Terrien

This one was first used at the Hong Kong concert and during the Tolerance Concert, at the Eiffel Tower. The laser is located under the stage in which a hole has been made for the beams to go through. The laser beam is reflected by a mirror mounted on a G350 scanner of General Scanning. It is a positioning scanner chosen for its good response to square signals. A photo-cell is placed near the scanner, facing upwards. This cell receives the light reflected by the hand of the artist when he places it into the beam.

The software runs under Windows. It drives an analog input-output card and a MIDI card. One of the analogical outputs is for the position of the scanner : each voltage corresponds to a position of the beam ( each “string” of the harp ) and the positionning frequency is fast enough (>25Hz) for the spectator to see all the beams at once (though there is only one). Another analogical output is for fading the laser (fade in and fade out). The analogical inputs read the voltage of the cell and also foot-switches used for calling the different memorized scales.

The software sets :

The MIDI channel of the scale, the number of beams (notes) of the scale, the note of each beam, the MIDI controler corresponding to the light variations . (If the artist chooses, for example, a modulation effect for this parameter, he can modulate the sound by changing the angle or the height of his hand in the beam), the fading-in time of the beams., the fading-out time of the beams and the trigger-level for the cell.

The algorithm of the software is very simple :

[1] : Sending the position of a beam.
[2] : Reading the cell and sending of the MIDI note corresponding to this beam if the light level indicates that the hand of the artist is in the beam.
[3] : Next beam.
[4] : Back to [1]

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