Digital Symphony: The Arduino Laser Harp

The Laser Harp is the ultimate performance art piece. Famously used by Jean-Michel Jarre, it removes physical strings entirely, replacing them with thick beams of light. When your hand interrupts a beam, the instrument screams to life.

Two Design Methods

1. The Parallel Method (Simpler): You mount 8 separate KY-008 Laser modules in a wooden frame pointing straight up. At the top of the frame, you mount 8 separate LDRs (Photoresistors). You use analogRead() on 8 different Arduino pins to see which beam broke.
2. The Galvo/Stepper Method (Advanced Frameless): A single powerful laser hits a mirror mounted rapidly on a stepper motor. The mirror sweeps so fast it creates the illusion of a "fan" of 8 beams spreading into the night sky. A single, highly sensitive photocell on the ground looks for the reflection off your hand to know exactly when the mirror hit that specific angle!

MIDI Integration

Instead of playing annoying tone() beeps, the Laser Harp produces professional audio.

• The Arduino acts as a MIDI Controller (Musical Instrument Digital Interface).
• When beam 3 is broken, it sends a standardized MIDI packet (e.g., Note On, Velocity 127, Pitch 64) out through its TX pin or via USB.
• This plugs directly into an iPad or a PC running GarageBand or Ableton Live, allowing your laser beams to sound like aggressive dubstep synthesizers or a grand piano!

Essential Parts

• Arduino Uno/Mega: Or Arduino Leonardo for direct USB-MIDI.
• 5V Laser Diodes (x8).
• LDRs (Photoresistors) (x8) + 10k-ohm resistors.
• A MIDI output jack or USB connection.