Jeff's Raspberry Pi Laser Projector

This Laser Projector uses a set of 20k point-per-second galvonometers with controller cards and power supply purchased on eBay. It is controlled by a Raspberry Pi 3B+ programmed completely in Python.

It is a reboot of a High School project I built in 1982 that had used audio speakers, a sine wave function generator, and audio input. That simple version used crossed sticks with a single mirror glued at the center, one end of each end fixed to a frame, and the free end resting on a speaker cone. It made Lissajous patterns and interesting effects with music, but had very limited angular sweep and a lot of unwanted X-Y coupling due to the single mirror.

This newer version was inspired by a colleague's Arduino and C++ project, which in turn was based on several on-line projects, possibly including: Instructables - Arduino Show With Real Galvos.


The results have been better than expected and meet my initial goals.

The ICs on the breakout proto-board are: MCP4822 12-bit DAC, TL084IN Quad-Op-Amp, L293D quad-half-H-bridge driver. Then a 9v to 5v power supply module.
The Op Amps will be used to expand the DAC's 0v to 4.095v output to +10v/-10v for larger projection angles. It currently works fine without that, the image is just small.
The H-bridge chip switches the laser since I did not have an individual JFET or MOSFET handy and it is safe for TTL input.
The L293D is only rated for 5kHz but seems to be turning the laser on and off ok for images at 20k points-per-second, of course for many of those points the laser remains on more than off.
The standard ILDA Test Image above shows shows poor resolution due to the low amplification and large beam diameter of my cheap laser module, but shows proper function with a small laser "blanking" timing issue I can live with.

See this Animation of Canada Goose in flight. Special thanks to for providing the CanGoose.ild file.

Main coding tasks completed:

Challenges: Next steps: References/Credits:
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