Playing the harp isn’t the most high-tech pastime—unless, like Stephen Hobley, you use lasers in place of the strings. Though not the first home-built laser harp, Hobley’s creation is unquestionably the coolest. Played by disrupting the laser beams with his hands, it can produce just about any sound. Better yet, it’s also a fully functioning controller for a version of Guitar Hero.

The harp consists of a box with a power supply, a 450-milliwatt green laser, a mirror and a motherboard. After determining the beam’s frequency, Hobley was able to tune a sensor so it would detect only the laser and not any ambient light. Touching a beam deflects light toward the sensor, triggering software on a PC that translates hand movements into sounds. He also wrote a script that maps notes from the harp to keyboard controls in the video game.

Hobley is now selling the plans for the harp on his web site ( He says he’s recently had to upload a video of himself playing the game: “It was a direct response to all the comments I got to ‘play Freebird!'”

How it works

  • Time: 10 days
  • Cost: $1,500


The beam reflects off a fast-moving motorized mirror, fooling the eye into seeing 10 lasers instead of one.


Hobley moves his hands up and down the ends of the beams to affect the sound. A Nintendo Wiimote on the sensor tracks his hand movements, and the data is sent via Bluetooth to the computer to create effects like swooshes and pitch bends.


Hobley wrote a script that maps signals from the harp into keystrokes for a PC version of Guitar Hero called Frets on Fire.

This story has been updated. It was originally featured in the August 2008 issue of Popular Science magazine.