LAYZOR!!! is a laser light show projector made with scrounged parts and designs and software from the Web.

This project started when Tom Gralewicz showed me a pair of X-Y galvanometers in his junk box. I decided I could make a laser light show projector with them, so I browsed around on the web and came across several designs based on hooking a USB sound card to a computer to generate the signals. Thus was LAYZOR!!! born.

LAYZOR!!! uses a USB 5.1-channel sound card as a DAC to generate signals to a set of galvanometers, which deflect the beam from a green laser pointer in X & Y to draw animations on a screen. The sound card generates a 2.4±1.2v signal, whereas the galvanometers expect a -10-10v input, so the signal has to be routed through a correction amp to offset it by -2.4v and amplify it by about 8x. The correction amp boards are based on this schematic, modified slightly to use the components we had on hand at MMS.

The laser source is a Radio Shack green laser pointer. Because this is a diode-pumped solid state laser, it takes a bit of time (maybe 10ms) to turn on. Thus, I was unable to effectively PWM the power input to modulate it, so I decided to use another galvo pair to aim the beam either at or away from the X-Y galvo. This is shown as Galvos 1&2 in the diagram above. The Y galvo of this pair is just used to center the beam vertically on the X-Y galvo pair's mirrors, but the X galvo is modulated using channel 3 of the USB sound card to either direct the beam toward or away from the X-Y galvos. The beam is passed adjacent to a razor blade (just to provide a nice sharp edge with no diffraction), and can actually be partially occluded by blade to attenuate the beam, giving me an analog intensity channel.

The software I'm using is called OpenLase, by Héctor Martín Cantero (a/k/a marcan). He describes it on his blog.