Teardown: What’s Inside A Christmas Laser Projector?

January 22, 2018 by 55 Comments

In the world of big-box retail, December 26th is a very special day. The Christmas music playing on the overhead speakers switches back to the family friendly Top 40, the store’s decorations get tossed in the compactor, and everything that’s even remotely related to the holiday is put on steep clearance. No more money to be made on the most commercialized of all holidays, so back to business as usual.

It’s in this narrow corridor of time, between the Great Holiday Unloading and the new spring products coming in, that you can find some fantastic deals on Christmas decorations. Not that long ago, this would hardly be exciting news for the readers of Hackaday. But Christmas lights and decorations have really started pushing the envelope in terms of technology: addressable RGB LED strands, Bluetooth controlled effects, and as of the last couple years, friggin’ lasers.

That’s right, you’ve seen them all over the neighborhood, probably took a few stray beams to the eye, you might even own your own. Laser projectors have been one of the most popular Christmas decorations for the last couple of years, and it’s not hard to see why. Just set the projector up in front of your house, and you’re done. No need to get on a ladder and string lights on the roof when you can just blast some directed energy up there instead.

Given how popular they are, I was surprised to see a lone Home Accents Holiday Multi-Color Light Projector on the clearance rack at Home Depot for around $14 a few days after Christmas. This was a 75% price reduction from normal MSRP, and right in that sweet impulse-buy price range. Let’s see what’s hiding inside!

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Laser Cutter Alignment Mod Skips Beam Combiner

December 11, 2017 by 27 Comments

A lot of the DIY laser engravers and cutters we cover here on Hackaday are made with laser diodes salvaged from Blu-ray drives and projectors, which are visible lasers in the 400 – 450nm range (appearing as violet or blue). Unfortunately there is an upper limit in terms of power on visible diode lasers, most builds max out at 5W or so. If you need more power than that, you’ll likely find yourself looking at gas laser cutters like the K40. While the K40 is a great starting point if you’re looking to get into “real” lasers, it’s a very different beast from the homebrew builds using visible lasers.

With a gas laser the beam itself is invisible, making it much more difficult to align or do test runs. One solution is to add a visible laser to the K40 which can be used to verify alignment, but making sure it’s traveling down the same path as the primary laser usually requires an expensive beam combiner. Looking to avoid this cost, [gafu] wanted to see if it was possible to simply move the visible laser into the path of the primary beam mechanically.

An adjustable microswitch detects when the lid has been opened.

In the setup that [gafu] has come up with, a cheap laser module (the type from a handheld laser pointer) is moved into the path of the primary laser on an arm that’s actuated by a simple hobby servo. To prevent the primary and visible lasers from firing at the same time, an Arduino is used to control the servo given the current state of the K40’s lid. If the lid of the K40 is open, the primary laser is shutoff and the visible laser is rotated into position so the operator can see where the primary laser’s beam would be hitting. Once the lid is closed, the visible laser rotates out of the way and the primary is powered back up.

Running the cutting or engraving job with the lid of the K40 machine open now let’s [gafu] watch a “dry run” of the entire operation with the visible laser before finally committing to blasting the target with the full power beam.

We’ve covered many hacks and modifications for everyone’s favorite entry-level CO2 laser cutter. From replacing the controller to making it bigger, K40 owners certainly seem like a creative bunch.

Laser Levitation With Scrap Parts

November 8, 2017 by 37 Comments

After a year away from YouTube, the ever-energetic [Styropyro] has returned with whiteboard in hand to remind us just how little we actually know about lasers. In the last month he’s really hit the ground running with plenty of new content, but one video of his particularly stands out: a practical demonstration of laser levitation. Even better, unlike most of his projects, it looks like we can replicate this one without killing ourselves or burning our house down!

For those unaware, laser levitation is probably as close as we’ll get to Star Trek-style tractor beams in our lifetimes. In fact, the NASA Innovative Advanced Concepts program has been examining using the technology for capturing small particles in space, since it would allow sample collection without the risk of physical contamination. While the demonstration [Styropyro] performs lacks the “tractor” part of the equation (in other word’s, there’s no way to move the particle along the length of the beam) it does make us hopeful that this type of technology is not completely outside the reach of our home labs.

The trick seems to be with the focus of the laser beam itself. Your average laser pointer just doesn’t have the appropriate beam for this kind of work, but with a diode pulled from a DVD burner and a driver circuit made from parts out of the junk bin, the effect can be demonstrated very easily as long as you can keep the air in the room extremely still. Of course, what you’re trying to pick up is also very important, [Styropyro] has found that synthetic diamond powder works exceptionally well for this experiment. At about $1.60 a gram, it won’t break the bank either.

So how does it work? With a few trips to the aforementioned white board, Professor Pyro explains that the effect we’re seeing is actually electromagnetic. If the particle you want to levitate is small enough it will become polarized by the light, which is in itself an electromagnetic wave. Once you’ve got your mind wrapped around that, it logically follows that the levitating particle will experience the Lorentz force. Long story short, the particle is suspended in the air for the same reason that a projectile is ejected from a rail gun: if you’ve got enough power and the mass of the object is low enough, there will be an observable force.

We’ve been covering the work of [Styropyro] for years now, and are glad to see him back on YouTube creating new content and terrifying a new generation of viewers. Between this and the return of [Jeri Ellsworth], it’s like we’re experiencing a YouTube hacker Renaissance.

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A Mechanical Laser Show With 3D-Printed Cams And Gears

June 15, 2017 by 22 Comments

Everyone knows how to make a POV laser display — low-mass, first-surface mirrors for the X- and Y-axes mounted on galvanometers driven rapidly to trace out the pattern. [Evan Stanford] found a simpler way, though: a completely mechanical laser show from 3D-printed parts.

The first 10 seconds of the video below completely explains how [Evan] accomplished this build. A pair of custom cams wiggles the laser pointer through the correct sequences of coordinates to trace the desired pattern out when cranked by hand through a 1:5 ratio gear train. But what’s simple in concept is a bit more complicated to reduce to practice, as [Evan] amply demonstrates by walking us through the math he used to transfer display shapes to cam profiles. If you can’t follow the math, no worries — [Evan] has included all the profiles in his Thingiverse collection, and being a hand model software guy by nature, he’s thoughtfully developed a program to automate the creation of cam profiles for new shapes. It’s all pretty slick.

Looking for more laser POV goodness? Perhaps a nice game of laser Asteroids would suit you.

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Robot Targets Eyeballs, Fires Lasers. OSHA’s Gonna Love This One

April 18, 2017 by 60 Comments

If you even think about hacking with lasers, you’re going to hear about eye safety. “Be careful” they’ll say. “Don’t look into laser with remaining eye” is a joke you’ll not be able to avoid. You’ll hear “Where are your goggles”, and about 1000 other warnings. Don’t get us wrong, laser/eye safety is important. However, the constant warnings can get a bit old — especially when you’re working with a “low power” class 3a laser — you know, the kind with a warning label that says “AVOID DIRECT EYE EXPOSURE” in big black letters on a yellow background.

[Michael Reeves] got fed up, and went a bit nuts. He built a robot specifically to shine a laser into human eyes. No, not a medical robot. This ‘bot lives in a pizza box, is built from servos, duct tape, and [Michael’s] tears. It just shoots lasers at people’s eyes. Needless to say, please, don’t try this at home, or at all.

Designing such a diabolical beast was actually rather simple. The software is written in C#. Frames are captured from an old Logitech webcam, then passed into Emgu CV, which is a .NET wrapper for OpenCV. [Michael] runs a simple face detection algorithm, and uses the results to aim a laser. The laser is mounted on two R/C style servos. An Arduino forms the glue between the servos and the PC.

[Michael] has a great deadpan delivery and it all makes for a great video. Think of him of a younger [Medhi] over at Electroboom.  But we can’t condone this behavior. Properly labeled and characterized red laser pointers have never been shown to cause eye damage. Yet if the laser is out-of-spec or reflects of something that further focuses the beam it is certainly capable of damaging eyesight.

We want [Michael’s] eyesight to remain intact so he can make more videos — he’s entertaining, even if ignoring safety warnings isn’t.

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Real-Time Planet Tracker With Laser-Point Accuracy

December 14, 2016 by 25 Comments

Space. The final frontier. Unfortunately, the vast majority of us are planet-locked until further notice. If you are dedicated hobbyist astronomer, you probably already have the rough positions of the planets memorized. But what if you want to know them exactly from the comfort of your room and educate yourself at the same time? [Shubham Paul] has gone the extra parsec to build a Real-Time Planet Tracker that calculates their locations using Kepler’s Laws with exacting precision.

An Arduino Mega provides the brains, while 3.5-turn-pan and 180-degree-tilt servos are the brawn. A potentiometer and switch allow for for planet and mode selection, while a GPS module and an optional MPU9250 gyroscope/magnetometer let it know where you are. Finally a laser pointer shows the planet’s location in a closed room. And then there’s code: a lot of code.

The hardware side of things — as [Shubham Paul] clarifies — looks a little unfinished because the focus of the project is the software with the intent to instruct. They have included all the code they wrote for the RTPT, providing a breakdown in each section for those who are looking to build their own.

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A Laser Effect Projector Built With Safety In Mind

November 17, 2016 by 29 Comments

There’s just something about wielding a laser pointer on a dark, foggy night. Watching the beam cut through the mist is fun – makes you feel a little Jedi-esque. If you can’t get enough of lasers and mist, you might want to check out this DIY “laser sky” effect projector.

The laser sky effect will probably remind you of other sci-fi movies – think of the “egg scene” from Alien. The effect is achieved by sweeping a laser beam in a plane through swirling smoke or mist. The laser highlights a cross section of the otherwise hidden air currents and makes for some trippy displays. The working principle of [Chris Guichet]’s projector is simplicity itself – an octagonal mirror spun by an old brushless fan motor and a laser pointer. But after a quick proof of concept build, he added the extras that took this from prototype to product. The little laser pointer was replaced with a 200mW laser module, the hexagonal mirror mount and case were 3D printed, and the mirrors were painstakingly aligned so the laser sweeps out a plane. An Arduino was added to control the motor and provide safety interlocks to make sure the laser fires only when the mirror is up to speed. The effect of the deep ruby red laser cutting through smoke is mesmerizing.

If laser sky is a little too one-dimensional for you, expand into two dimensions with this vector laser projector, and if monochrome isn’t your thing try an RGB vector projector.

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