Electronics Novice

You would need one light sensor such as a photo diode or a photo transistor for each string.

You could also have a laser emitter for each string, but if each sensor is just focused on a small area, the whole line of stings can have the same light source. You can make the sensor only see a small area by putting a long thin black tube in front of it. If the tube has a 1 mm inner diameter and is 100 mm long, the spot it sees 300 mm from the tube opening is only 3 mm.

If you mean this sort of thing:

https://www.kromalaser.com/laser-harp

Then wait until you are not a novice !!!

(No idea how the audience and guy playing it are protected - looks risky to me - we wouldn't be allowed to do this in an office or factory !)

1W + lasers - please do not go there without actual training.

If you want to make a miniature home use device you could use LEDs but the hard stuff will be in the optics.

MK

These two 'The Ben Heck Show' episodes may be of interest:

Episode 253: Ben Heck’s Intel Edison Laser Harp Part 1: Design Episode

Episode 254: Ben Heck’s Intel Edison Laser Harp Part 2: Assembly Episode

Also this one may be of some interest:

LASER HARP

This one is based on a 375mW laser:

From Wikipedia:

Class IIIb

Lasers in this class may cause damage if the beam enters the eye directly. This generally applies to lasers powered from 5–500 mW. Lasers in this category can cause permanent eye damage with exposures of 1/100th of a second or more depending on the strength of the laser. A diffuse reflection is generally not hazardous but specular reflections

can be just as dangerous as direct exposures. Protective eyewear is recommended when direct beam viewing of Class IIIb lasers may occur. Lasers at the high power end of this class may also present a fire hazard and can lightly burn skin.

If you play with matches .........

MK

I seem to recall that local Trading Standards found a number of cheap import laser pointers on the market were outputting far in excess of their claimed class I or class II ratings.

Also I recall that sometimes the class rating takes into account the protective enclosure, so if you remove the laser diode from its original product housing then the rating can change.

Hi,

There are safer non-laser methods, maybe using a camera perhaps.

If you're happy with a software solution, there is Leap Motion, that might work for this use-case. It is very responsive (several hundred frames per second) because it is intended for gaming, and provides a value in millimetres of where your hand or fingers are, in 3 dimensions.

Some info here: Virtual Reality, Leap Motion, and Controlling Things! - Getting Started Guide

Or if you want it to be a hardware project, then experimentation with LEDs and lenses could help, although it gets expensive fast, when it comes to optics : (

Cornell ECE4760 student project

https://youtu.be/kHuugv6sa_U

More info at:

Laser Harp