Poor Man’s Laser Scanner Probably Won’t Shoot Your Eye Out, Kid

Yes, laser cutters that come off the slow boat from China are more affordable than ever, and with some tweaks and hacks they can turn out some decent results. But if you just want a laser lightshow that’ll draw boxes on your living room ceiling, this simple X-Y laser scanner might be a good platform to build.

Let’s say right up front that there are more than a few safety issues with [ThingEngineer]’s 3D-printed two-axis scanner. He’s well aware of these potential retina-cooking issues and duly notes that a good pair of laser safety goggles is a must and that the cheap anti-lawsuit glasses that laser module manufacturers often include with their products don’t count.

[Editor’s Note: Glasses are really only intended for alignment operations. Pros enclose lasers beyond a certain power to prevent anyone going blind. Know where your beam terminates, kids.]

With that in mind, there’s a lot to be said for this poor man’s scanner build. Yes, it would be faster with real galvos and low-mass mirrors, but time is money, and the steppers and craft store mirror discs do the job, albeit slowly. We like that everything is so simple, even the method for turning a regular mirror into a front-surface mirror.

[ThingEngineer] proves you don’t need galvanometers to have some simple laser fun. And if steppers don’t do it for you, you can try little brushed DC hobby motors or even 3D-printed cams.

13 thoughts on “Poor Man’s Laser Scanner Probably Won’t Shoot Your Eye Out, Kid

  1. It may not be fast, but it does seem to be accurate. The slowmo shot shows some nice sharp corners. Might work great in 3d scanner rig along side a high speed camera for some fast 3d scans of an object. Makes me wonder what path would be most efficient, scanning left and right, zigzag, or maybe even a spiral.

  2. I built one from instructables that used pieces of hard drive platter as the front face mirrors and regular DC motors hooked to a stereo Amp as the x y motors. A rubberband returns them to center. Can’t make specific shapes but with a cheap fog machine it blew my 6yr Olds mind lol

    1. If you were pulling platters out of a hard drive, the voice coils/head positioning motors make for some decent diy galvo’s if you slice the read head arm off and put a mirror (relatively cheap first surface is worth the bit more money) on near the pivot axis. I used a rubber band stretched across back of voice coil to spring return to center, and it gave some pretty decent results, being able to write letters and whatnot. That was way back in high school though… Was amusing to younger siblings to be able to be able to use my little HeNe tube to write things on our water tower.

    2. OLD CRT based projection televisions contain large high quality first surface mirrors (in addition to projection lenses, an occasional large Fresnel lens, speakers, and more goodies) and can still be found for free at the curb with regularity… until everyone has upgraded to modern sets.

  3. Why not get rid of the excess mass of those circular mirrors to speed it up and avoid overshoot? The first mirror can be very small with center of mass centered on the axis of the motor shaft. The second mirror can be a thin rectangle with long axis on the axis of the second motor shaft. Cut mass by a factor of 10 or more and angular momentum by even more.

    That is how the geometry works, isn’t it? Just trying to picture it.

    Pretty dang cool. In the photos those look like plain second surface mirrors. Get your self some little first surface mirrors for an impressive improvement in image quality and dot size – right now you are getting dots from 4 different reflected images. Front surface will be a single dot. Also, if the reflective surface is not inline with the center of rotation of the shaft, it messes up your geometry. A dentist can give you some disposable/replaceable mouth mirrors that are first surface.

    I’m gonna print that.

  4. Or get the optics out of a vintage LaserDisc player. He-Ne coupled to two X Y mirrors with low frequency non feedback galvos ready to go. No hack except to wire ’em up, but they certainly weren’t meant to hooked up that way.

  5. Thanks for very visibly including safety alerts! Probably very necessary given the wide range of experience of your readers, that is probably wise :(

    *Before* health and safety became paranoid, British Telecom Martlesham Labs were paranoid about any reflecting surfaces, had sign “Do not look into laser beam with remaining eye”, and showed videos of what happened to primates’ faces (before they were euthanased).

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