laser

A Foggy Lightsaber Build

January 4, 2019 by 5 Comments

Lightsabers have enchanted audiences since their appearance in the very first Star Wars film in 1977. Unfortunately, George Lucas hasn’t shared the technology in the years since then with the broader public, so we’re left to subsist on pale imitations. This is just such a build.

The closest human analog to Jedi technology is the laser, and this build uses 8 of them in combination with two LEDs. They’re aimed to coincide at a fixed distance above the hilt. A CO2 bicycle inflater is then used to blow through an e-cigarette to create a fog. This makes the red lasers readily visible to the human eye.

This ersatz lightsaber does have its limitations – fast motion tends to scatter the fog, making it once again invisible, and it’s really at its best held in a vertical orientation. There’s also some divergence beyond the focused point. With that said, it does look somewhat impressive when held still, smouldering away.

Until we gain a better mastery of plasma physics, perhaps you can make do with this fire-based build? Video after the break.

[Thanks to qrp-gaijin for the tip!]

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Laser Harp Sounds Real Thanks to Karplus-Strong Wave Equation

December 29, 2018 by 9 Comments

The harp is an ancient instrument, but in its current form, it seems so unwieldy that it’s a wonder that anyone ever learns to play it. It’s one thing to tote a rented trumpet or clarinet home from school to practice, but a concert harp is a real pain to transport safely. The image below is unrelated to the laser harp project, but proves that portable harping is begging for some good hacks.

Concert grand harps are so big there’s special equipment to move them around. This thing’s called the HarpCaddy

Enter this laser harp, another semester project from [Bruce Land]’s microcontroller course at Cornell. By replacing strings with lasers aimed at phototransistors, [Glenna] and [Alex] were able to create a more manageable instrument that can be played in a similar manner. The “strings” are “plucked” with the fingers, which blocks the laser light and creates the notes.

But these aren’t just any old microcontroller-generated sounds. Rather than simply generating a tone or controlling a synthesizer, the PIC32 uses the Karplus-Strong algorithm to model the vibration of a plucked string. The result is very realistic, with all the harmonics you’d expect to hear from a plucked string. [Alex] does a decent job putting the harp through its paces in the video below, and the write-up is top notch too.

Unique musical instruments like laser harps are far from unknown around these parts. We’ve seen a few that look something like a traditional harp and one that needs laser goggle to play safely, but this one actually looks and sounds like the real thing. Continue reading “Laser Harp Sounds Real Thanks to Karplus-Strong Wave Equation” →

Experiment With Lumia, The Cheap and Easy Way

December 22, 2018 by 11 Comments

Light is a wonderful medium for art, and there’s all manner of ways to approach it. We’ve always been huge fans of all that blinks and glows, but there’s a whole wide world of other methods and techniques in the lighting arena. Lumia is one that does not always get a lot of mainstream attention, and so [Adam Raugh] has created this video, sharing both the history of the effect, and various ways to create it yourself. 

Lumia was once used to refer to a broad swathe of artistic lighting, but these days, more commonly refers to effects that create an aurora-like appearance, as one would see near the poles of our fine Earth. [Adam] first covers the history of the effect, as pioneered by Thomas Wilfred with the Clavilux in the early part of the 20th Century.

The video then covers the basics of creating lumia effects using DIY methods. The key is to combine slow rotation with an organically deformed refractive medium. [Adam]’s rig of choice is a basic laser projector, rotating at just 1/3 of a rotation per minute. This is then combined with a variety of homebrewed refractive media – torture tubes made from glass, acrylic sheets coated with muddled epoxy, and even a crumpled water bottle.

It’s an excellent primer on how to get started with lumia, and [Adam] covers a wide variety of tips and tricks as well as potential pitfalls to avoid.

We see plenty of great lighting projects around these parts – check out the Kinetic Chandelier. Video after the break.

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[Ben Krasnow] Builds a One-Component Interferometer

December 13, 2018 by 31 Comments

When we think of physics experiments, we tend to envision cavernous rooms filled with things like optical benches, huge coils in vacuum chambers, and rack after rack of amplifiers and data acquisition hardware. But it doesn’t have to be that way – you can actually perform laser interferometry with a single component and measure sub-micron displacements and more.

The astute viewer of [Ben Krasnow]’s video below will note that in order to use the one component, a laser diode, as an interferometer, he needed a whole bunch of support gear, like power supplies, a signal generator, and a really, really nice mixed-signal oscilloscope. But the principle of the experiment is the important bit, which uses a laser diode with a built-in monitoring photodiode. Brought out to a third lead, older laser diodes often used these photodiodes to control the light emitted by the laser junction. But they also respond to light reflected back into the laser diode, and thanks to constructive and destructive interference, can actually generate a signal that corresponds to very slight displacements of a reflector. [Ben] used it to measure the vibrations of a small speaker, the rotation of a motor shaft, and with a slight change in setup, to measure the range to a fixed target with sub-micron precision. It’s fascinating stuff, and the fact you can extract so much information from a single component is pretty cool.

We really like [Ben]’s style of presentation, and the interesting little nooks and crannies of physics that he finds a way to explore. He recently looked at how helium can kill a MEMS sensor, an equally fascinating topic.

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Spring-Loaded Bed for K40 Laser Acts As an Auto-Focus

December 2, 2018 by 9 Comments

Laser engraving and cutting has something in common with focusing the sun’s rays with a magnifying glass: good focus is critical to results. If materials of varying thicknesses are used, focus needs to be re-set every time the material changes, and manual focusing quickly becomes a chore. [Scorch Works] has a clever solution to avoid constant re-focusing that doesn’t involve sensors or motors of any sort. The result is a self-adjusting bed that compensates for material height changes, ensuring that the top surface of the material is always a fixed distance from the laser’s head.

The way [Scorch Works] has done this is to make two spring-loaded clamps from angle aluminum and a few pieces of hardware. When a sheet of material is placed into the machine, the edges get tucked underneath the aluminum “lips” while being pushed upward from beneath. By fixing the height of the top layer of angle aluminum, any sheet stock always ends up the same distance from the laser head regardless of the material’s thickness.

[Scorch Works] shows the assembly in action in the video embedded below, along with a few different ways to accommodate different materials and special cases, so be sure to check it out.

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Kind of the Opposite of a Lightsaber

November 22, 2018 by 22 Comments

Lightsabers are an elegant weapon for a more civilized age. Did you ever consider that cutting people’s hands off with a laser sword means automatically cauterized wounds and that lack of blood results in a gentler rating from the Motion Picture Association? Movie guidelines aside, a cauterizing pen is found in some first aid kits, but at their core, they are a power source and a heating filament. Given the state of medical technology, this is due for an upgrade, and folks at Arizona State University are hitting all the marks with a combination of near-infrared lasers, gold particles, and protein matrix from silk.

Cauterizing relies on intense heat, or chemicals, to burn flesh but this process uses less power by aiming the near-IR laser at only the selected areas, and since near-IR can penetrate soft-tissue it goes deep without extra heating. The laser heats the gold, and that activates the silk proteins. Early results are positive but lots of testing remains and it still will not belong in the average first aid kit for a while, lasers and all, but surgery for beloved pets and tolerable humans could have recovery time reduced with this advance.

If this doesn’t sate your need for magical space knight weaponry, we have options aplenty.

Via IEEE Spectrum. Image: starwars.com

Scratch-Building A Supersized Laser Cutter

November 20, 2018 by 9 Comments

Now that 3D printers have more or less hit the mass market, hackers need a new “elite” tool to spend their time designing and fiddling with. Judging by the last couple of years, it looks like laser cutters will be taking over as the hacker tool du jour; as we’re starting to see more and more custom builds and modifications of entry-level commercial models. Usually these are limited to relatively small and low powered diode lasers, but as the following project shows, that’s not always the case.

This large format laser cutter designed and built by [Rob Chesney] is meticulously detailed on his blog, as well as in the in the video after the break. It’s made up of aluminium profile and a splattering of ABS 3D printed parts, and lives in an acrylic enclosure that’s uniquely isolated from the laser’s internal gantry. All told it cost about $2,000 USD to build, but considering the volume and features of this cutter that’s still a very fair price.

[Rob] carefully planned every aspect of this build, modeling the entire machine in CAD before actually purchasing any hardware. Interestingly enough his primary design constraint was the door to his shed: he wanted to build the largest possible laser cutter that could still be carried through it. That led to the final machine’s long and relatively shallow final dimensions. The design was also guided by a desire to minimize material waste, so when possible parts were designed to maximize how many could be cut from a one meter length of aluminum extrusion.

The laser features a movable Z axis that’s similar in design to what you might see in a Prusa-style 3D printer, with each corner of the gantry getting an 8 mm lead screw and smooth rod which are used in conjunction to lift and guide. All of the lead screws are connected to each other via pulleys and standard GT2 belt, but as of this version, [Rob] notes the Z axis must be manually operated. In the future he’ll be able to add in a stepper motor and automate it easily, but it wasn’t critical to get the machine running.

He used 3D printed parts for objects which had a relatively complex geometry, such as the laser tube holders and Z axis components, but more simplistic brackets were made out of cut acrylic. In some components, [Rob] used welding cement to bond two pieces of acrylic and thereby double the thickness. Large acrylic panels were also used for the laser’s outer enclosure, which was intentionally designed as a separate entity from the laser itself. He reasoned that this would make assembly easier and faster, as the enclosure would not have to be held to the same dimensional tolerances as it would have been if it was integrated into the machine.

[Rob] gives plenty of detail about all the finer points of water cooling, laser control electronics, aligning the mirrors, and really anything else you could possibly want to know about building your own serious laser cutter. If you’ve been considering building your own laser and have anything you’re curious or unsure about, there’s a good chance he addresses it in this build.

Short of having the fantastically good luck to find a laser cutter in the trash that you can refurbish, building your own machine may still be the best upgrade path if you outgrow your eBay K40.

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