Cheap Dual Mirror Laser Projector

[Stanley] wanted to make a laser projector but all he could find online were one’s using expensive galvanometer scanners. So instead he came up with his own solution that is to be admired for its simplicity and its adaptation of what he could find.

At its heart is an Arduino Uno and an Adafruit Motor Shield v2. The green laser is turned on and off by the Arduino through a transistor. But the part that makes this really a fun machine to watch at work are the two stepper motors and two mirrors that reflect the laser in the X and Y directions. The mirrors are rectangles cut from a hard disk platter, which if you’ve ever seen one, is very reflective. The servos tilt the mirrors at high speed, fast enough to make the resulting projection on the wall appear almost a solid shape, depending on the image.

He’s even written a Windows application (in C#) for remotely controlling the projector through bluetooth. From its interface you can select from around sixteen predefined shapes, including a what looks like a cat head, a heart, a person and various geometric objects and line configurations.

There is a sort of curving of the lines wherever the image consists of two lines forming an angle, as if the steppers are having trouble with momentum, but that’s probably to be expected given that they’re steppers controlling relatively large mirrors. Or maybe it’s due to twist in the connection between motor shaft and mirror? Check out the video after the break and let us know what you think.

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Cheap (Free?) Mirror Replacement for your CO2 Laser

hdd mirrors

You know what’s expensive? Those little tiny little mirrors used in laser cutters — and they don’t last forever either! What if we told you it’s possible to make your own for free, using a broken hard drive?

[Tim Wehr] read about using HDD platters as mirrors on BuildLog.net, and decided to try it out for himself to see how well they work. He quickly salvaged an old hard drive and removed the ever so shiny platters. Using a few pieces of wood he clamped the platter and then cut circles out of it using a metal hole saw — the edges are a bit rough, so we’d recommend you invest in a diamond hole saw if you’re planning on trying this.

Some denatured alcohol polishing later and a bit of filing on the edges, and he had a replacement mirror. He then performed two tests using both the original and the HDD mirror on his CO2 laser. Almost identical cutting power. In fact, [Tim] muses that the HDD mirror looks like it cut slightly better even! Not bad!

[Thanks Riva!]