How does it work?

How does it do the magic? Technology behind the laser harp is not difficult to understand if you are a bit into engineering. If you aren't, you can just buy one one the market and play, but if you are curious, here the basics on Laser Harps techs!

At the very beginning there is a Laser Beam: Since the discover, in 1960, lasers have become ubiquitous, finding utility in thousands of highly varied applications in every section of modern society, including consumer electronics, information technology, science, medicine, industry, law enforcement, entertainment, fibre-optic communication...

The first use of lasers in the daily lives of the general population was the supermarket barcode scanner, introduced in 1974. The compact disc player was the first laser-equipped device to become popular, beginning in 1982 followed shortly by laser printers.
In the laser harp, it is used to make the "virtual strings" of the instrument. Since laser radiation goes straight and shows itself as a clear and very bright single beam of light, it is the perfect for represent one "string". But one string is not enough, so how do we get the 12 strings of an entire octave for playing?

The Main Components

Controller

The laser harp generator

Laser and scanner are nothing without the controller. It is the controller that drives the galvanometric head and modulates the beam in order to output 12 or more distinct beams from it. The micro controller drives the galvo motor to a predefined position, then turns the laser on. The laser stays on for some microseconds and next it is turned of, and the motor is driven to next position. The laser is turned on again and so on until the end of the path is reached. Then we start again. This technique is called scanning, like the old barcode scanners did. If it is done very fas (at least 100hz) the humane sees some standing beams in the air. And you can finally touch them. But it's not all...
Galvo Scanner

Moves your beam

The laser beam hits a mirror mounted on a rotating head, typically driven by a very fast galvanometer motor. The single beam becomes a "fan" distributed over a 30 degrees angle. This fan is not useful for playing, since it is a continuous fan and not an array o beams. We need some electronics to modulate the laser beam and synchronise it with the movement of the galvanometer rotating head. The speed of the galvanometer is typically more than 100 oscillations / sec
Sensor

The laser harp's eye

The sensor is the most critical component in a laser harp system. The sensor has to detect accurately which beam has been touched. To do this, it must be interfaced with the Controller unit. In a frameless laser harp, the sensor detects the election of the beam on the player's hand, and sends a signal to the controller unit. The controller checks which is the position of the galvanometer motor at that moment, and send a standard MIDI note ON command to an external synthesiser of another MIDI musical instruments. Who the hand leaves the beam, there is no light on the sensor anymore, and a MIDI note OFF command can be sent to stop the sound. The Sensor must be ambient light-aware, or it can not distinguish from the light in the room and the reflection of the beam on player's hand.

The Main Components

Controller

Galvo Scanner

Sensor