Success! Sort of. It makes a line, which is good. Unfortunately, it makes a rather crappy line. You can click on the image on the left to see the full size test image. The beam, even a few inches from the source has already spread two to three times its original width. Worse, it is dropping off in strength near the ends, which is probably an artifact of the rotating hex reflector.

Bottom line: The nut I'm using for a reflector is a bad mirror. The little bumps and pits, even though polished, are bouncing the light around all over the place, and not in a nice, sharply reflected beam.

It's not all bad news. Because there are six reflecting edges on the nut, the line is getting drawn in 6 sweeps for every single rotation of the motor. So the scan rate for the painter is 6 x Motor RPM, which means that even a fairly fast shutter speed should catch a full, painted line.

I need a standard test object to use as the 3d-scanner begins. I've settled on the 5" (13 cm) high figurine of Mark Anthony that I received a few years back as part of my Coolware program (Thanks, Raven!).

Here's the test image of Mark illuminated by the Mark I Painter. Click on the test to view the full size image. The full image is full of scattered reflection, and the wide beam makes it difficult to make out the features.

The other problem is the brightness. The image had to be greatly boosted in Photoshop, which is part of the reason it's so noisy. All elements considered, it's time to go back to the drawing board. Or more precisely, back to the large pile of post-it notes on my desk.

The Mark II

So, on to the good stuff! The Mark II. This is much slicker laser painter. The AVI on the right gives you a good visual representation of the core idea. Remove the bolt from the motor, and replace it with a mirror, mounted 45 degrees from the shaft of the motor.

Now, move the laser so it is pointing in line with the shaft of the motor. Now when the shaft spins, it draws a line in a 360 degree arc, perpendicular to the shaft.

First thing on the list: constructing the 45 degree reflector. I could go online and buy one, but why drop $50-$200, when an old AOL CD, and piece of Lego and a dab of glue will do nearly as well?

Using an Exacto Razor Saw (careful kids...sharp!) I cut a small rectangle out of a junk CD, and glued it onto the Lego bit.

Why did I choose these elements (aside from cost...about $0.02)? Well the CD is, by design, optically flat and designed to reflect lasers.Win! There are some drawbacks though; CDs are also designed to not reflect lasers (the 0s and 1s that allow you to store info are just areas that reflect, or not). They also tend to diffract light (as seen by the rainbow reflections they give off). But for free, how can I argue? At some point I'd like to pick up a small dental mirror, but that sounds like a job for...later.

And the Lego bit? Well, thank the fine Danish engineers at Lego, and the fact that all the Lego bits have to fit with all the other Lego bits. That 45 degree Lego piece is a well engineered, flat 45 degree slope. Win!

Look at that beam! Well, look at that photo of the beam. Looking at the beam itself is not a good idea. Bright (due to the new 5 mw laser pointer that...I admit...I bought for $40. Not pictured above, BTW), and sharp as can be. I may try to narrow the beam a bit, but for now...I'm very happy. It may look like the beam is a little curved in one of the photos, but it's the piece of tag board I'm projecting onto that is bent.

Time to consider moving on to the next step of the project: the camera. Or should I say...camera obscura? Stay tuned!

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