The devices are called Galvometers and they work like audio meters. There is in deed a mirror, and they are used in an XY pair. Old gas lasers used a RF driven crystal to select a specific wavelength of light (and deflect all other wavelengths.) Those crystal setups are known as Poly-chromatic acouso-optic modulation or PCAOM for short. The current fastest scanners that I know of on the market for laser show display would be the Pangolin Saturns. Next up would be something in the 6800 series from Cambridge Technology. The galvos can do sharp turns, text, and graphics. There is software for Linux that can do edge tracing and send it out of a modified sound card DAC (has to pass DC voltage?) to the X/Y scanner drivers. Most galvos have a feedback loop for inertial correction. The laser display world uses a test frame known as the ILDA (International Laser Display Association) and there is a performance benchmark in points per second, so 12,000 points per second is old spec, 30,000 points per second is a newer spec. Now people are claiming 60 and 90K on the modern, expensive, quality scanners. The Chinese stuff is mostly 30K and 40K. The old days 8 degrees was the scan width but now people push it way further. Old technology stored the laser show information on various formats for shows ... like 8 track multitrack reel to reel, and then the Alesis SVHS based ADAT machines were popular for a while. Now everything is directly driven from computer. Some of the old systems are being recovered here and there, and similar to vintage computers people pet them and clean them and take care of them. I'm pretty certain some old school stuff existed in the S100 world, but none of that has surfaced. There is also analog consoles and the like. As far as sending video from a computer frame buffer, I think it might be way too fast. Also, the more you scan and the faster you scan the laser power has to be higher. And there can also be issues with modulating the actual laser diodes. Direct solid state run at one rate and diode pumped solid state run at another rate. This is a random picking of a laser graphics show, projected on a scrim. It's from LD-2000 which would of been Windows 2000 to XP era software, but the show is pushed into a card that is a Motorola 68040 on a board with RAM where the card just runs the show once it's loaded. Pangolin's roots are on the Amiga so I've always grinned thinking they just put an Amiga on a board: https://www.youtube.com/watch?v=khVGAOLTaTA There are a few ports of MAME for running vector arcade games into laser projectors, the older hardware had quite a bit of flicker. There is also someone who has rebuilt, from scratch, several older analog consoles that had some fame. China really opened the floodgates with the availability of parts, and lots of projectors and low cost galvos. Before China a set of galvos could run a thousand or more dollars with the amps. And the PCAOM hardware would costs thousands. When I had the argon system I had picked it up from a NASA auction while hunting lasers, SGIs, and Suns. Everyone will probably cry when I say that one of the first NASA auctions I went to there was a Convex system there.

Given modern processor speeds, an obvious answer is to do it the same way the CDC mainframes drive the console: a program loop feeding coordinates to the interface. You just need a loop that takes less than the acceptable refresh interval (30-50 ms or so) which isn't hard to do. Especially since the deflection performance is likely to be the limiting factor. paul

Depending on the typesetter, the spinning mirror might just be horizontal deflection, with vertical positioning provided by the film transport motor. But in any case, those are raster scan systems. It's very easy to scan a light beam in a regular pattern at high speed, with schemes like this. DLP (micro-mirror chips) are also raster systems. paul