laser

Chinese Laser AK-47: Myth Or Reality?

July 9, 2018 by 162 Comments

 

Chinese company ZKZM Laser has produced the ZKZM-500 laser assault rifle which people are calling the Chinese AK-47 because of its similar size, weighing in at three kilos (6.6 lbs). Claims of its capabilities, however, are being disputed.

The South China Morning Post writes that the company claims the laser to:

  • be powered by a rechargeable lithium battery back,
  • have a range of 800 meters (0.5 miles),
  • have a beam that is invisible to the eye,
  • be able to fire 1000 “shots”, each no longer than two seconds,
  • be able to burn human flesh if held in place long enough,
  • be able to set fire to clothes and hair, and
  • be able to set fire to banners from a distance.

Burning things with lasers is nothing new but the disputes are mostly based around such a small laser being effective at an 800 meter range. To be fair, while the 800 meter range claim is everywhere, the Post writes that the company brochure says the range is 500 meters (0.3 miles), still quite a long distance.

[styropyro], a YouTuber with a lot of experience with lasers has done an analysis, starting by deducing a wavelength of around 2000 nanometers. He finds that at 800 meters the beam would have dispersed to a diameter of 26 cm (10 inches) and produce 53 W over that area. (EDIT: The 53 W is how much sunlight would produce for that area. In the video he carries the calculations further to work out the minimum power needed, ignoring losses, to light the cotton on fire, 645 W.) For 500 meters, using the same formula we calculate that the dispersion would be a diameter of 16 cm (6 inches) with 500 W spread over that area, which would get uncomfortable very fast, think of half a square meter of sunlight focused down to a circle of that diameter. (EDIT: Again, this it 500 W for sunlight, the laser produces more.) His video doesn’t include enough detail for us to replicate the remainder of the calculations so we’ll just have to go with the 800 meter claim. See the video below for his full analysis. If anyone else has any experience that’ll either support or dispute the claims then please share it with us in the comments.

After all the disputes against their claim, the Chinese company did produce a video firing the laser from a shorter distance. Check it out on this page by the post.

While waiting to see how much truth there is to the Chinese company’s claims we can sit back and enjoy [styropyro’s] home-brew high power ruby laser, both his build and him doing some serious damage with it.

Oh, and don’t try this at home. It’s probably in violation of the Geneva Convention on Certain Conventional Weapons in addition to common sense.

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Worn Train Rails Get Judged by Laser

July 8, 2018 by 32 Comments

[Calango] is a railway technician, and for a school final project created the Rail Wear Surveillance Trolley (RWST) which is a delightfully designed device made mainly from PVC conduit with one job: travel down a segment of train track while shining a green laser onto the rail, and capture camera images. The trolley holds both the laser and the camera at just the right angles for the camera to capture a profile of the rail’s curved surface. The images are sent via Bluetooth to a smartphone for later analysis. Rail wear can be judged by checking how well the profile of the rail conforms to the ideal profile of an unworn segment. The trolley is manually pushed by an operator, but [Calango] says that ideally, it would be self-propelled and able to inspect a length of the track then return on its own.

The project was made on a tight budget, which led to some clever solutions like using a rotary encoder attached to a wheel as a makeshift distance sensor. If things get desperate enough, it’s even possible to roll your own rotary encoder with a 3D printer and two microswitches.

Laser Draws Weather Report

June 23, 2018 by 13 Comments

Have you ever wished that a laser could tell you the weather? If you have, then [tuckershannon] has you covered. He’s created a machine that uses a laser and some UV sensitive paper to draw the temperature and a weather icon! And that’s not all! It’s connected to the internet, so it can also show the time and print out messages.

Building on [tuckershannon]’s previous work with glow-in-the-dark drawing, the brains inside this machine is a Raspberry Pi Zero. The laser itself is a 5mw, 405nm laser pointer with the button zip-tied down. Two 28BYJ-48 stepper motors are used to orient the laser, one for the rotation and another for the height angle. Each stepper motor is connected to a motor driver board and then wired directly to the Pi.

The base and arm that holds the laser were designed in SolidWorks and then 3d printed. The stepper motors are mounted perpendicular to one another and then the laser pointer mounted at the end. The batteries have been removed from the laser and the terminals are also wired directly to the raspberry pi. The Pi is then connected to Alexa via IFTTT so that it can be controlled by voice from anywhere.

The real beauty of [tucker]’s laser drawing machine is that is will draw out the temperature and weather icon, as well as drawing the time in either digital or analog forms! We’ve seen [tuckershannon]’s work before. The precursors to this project were his clock which uses a robotic arm with a UV LED on it to draw the time and another clock which uses similar robotic arm only with a laser attached. Let’s hope we get to see the rest of [tucker]’s progress!

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A Lesson in K40 Laser Repair

June 10, 2018 by 25 Comments

The K40 laser cutter has become ubiquitous in hackerspaces and well-equipped home workshops over the past few years, as a relatively inexpensive introduction to laser cutting and a machine that is readily hackable. Tokyo Hackerspace have one, but sadly their laser tube failed after relatively little use. Replacing a laser tube might be a routine component change for some readers, but it’s still worth looking at in some detail.

Their tube had failed at its output lens cooling cap, a component that is glued onto the end of the tube rather than bonded, and which had snapped off. There had been no mechanical stress upon it, but it was found  that the arrangement of their cooling system caused it to drain between uses and thus air bubbles could accumulate. The resulting cooling inefficiency caused enough thermal stress for the bond between the tube and the end piece to fail.

The in-depth analysis of what caused the failure and step-by-step description of the procedure should be of interest to any K40 owner. Little things such as ensuring that the tube is rotated to the right angle for all air bubbles to make their way out of it, or making sure that when the pump is switched off the water isn’t all pulled out of it by gravity seem obvious, but these are traps that will have caught more than one K40 owner.

We’ve covered many K40 stories over the years, but a good place to start for the novice might be this commissioning story, or even this tale of a hackerspace’s modifications to their model.

Robert Hall and the Solid-State Laser

May 22, 2018 by 13 Comments

The debt we all owe must be paid someday, and for inventor Robert N. Hall, that debt came due in 2016 at the ripe age of 96. Robert Hall’s passing went all but unnoticed by everyone but his family and a few close colleagues at General Electric’s Schenectady, New York research lab, where Hall spent his remarkable career.

That someone who lives for 96% of a century would outlive most of the people he had ever known is not surprising, but what’s more surprising is that more notice of his life and legacy wasn’t taken. Without his efforts, so many of the tools of modern life that we take for granted would not have come to pass, or would have been delayed. His main contribution started with a simple but seemingly outrageous idea — making a solid-state laser. But he ended up making so many more contributions that it’s worth a look at what he accomplished over his long career.

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Gorgeous NickelBot Serves Up Lasered Wooden Nickels

May 9, 2018 by 22 Comments

[bdring] just recently completed his absolutely fantastic NickelBot, which is a beautifully made unit that engraves small wooden discs with a laser like some kind of on demand vending machine, and it’s wonderful. NickelBot is small, but a lot is going on inside. For example, there’s a custom-designed combination engraving platform and hopper that takes care of loading a wooden nickel from a stack, holding it firm while it gets engraved by a laser, then ejects it out a slot once it’s done.

NickelBot is portable and can crank out an engraved nickel within a couple of minutes, nicely fulfilling its role of being able to dish out the small items on demand at events while looking great at the same time. NickelBot’s guts are built around a PSoC5 development board, and LaserGRBL is used on the software side to generate G-code for the engraving itself. Watch it work in the video embedded below.

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Roll Up Your Sleeve, Watch a Video with This Smart Watch Forearm Projector

April 25, 2018 by 35 Comments

We’re all slowly getting used to the idea of wearable technology, fabulous flops like the creepy Google Glass notwithstanding. But the big problem with tiny tech is in finding the real estate for user interfaces. Sure, we can make it tiny, but human fingers aren’t getting any smaller, and eyeballs can only resolve so much fine detail.

So how do we make wearables more usable? According to Carnegie-Mellon researcher [Chris Harrison], one way is to turn the wearer into the display and the input device (PDF link). More specifically, his LumiWatch projects a touch-responsive display onto the forearm of the wearer. The video below is pretty slick with some obvious CGI “artist’s rendition” displays up front. But even the somewhat limited displays shown later in the video are pretty impressive. The watch can claim up to 40-cm² of the user’s forearm for display, even at the shallow projection angle offered by a watch bezel only slightly above the arm — quite a feat given the irregular surface of the skin. It accomplishes this with a “pico-projector” consisting of red, blue, and green lasers and a pair of MEMS mirrors. The projector can adjust the linearity and brightness of the display to provide a consistent image across the uneven surface. An array of 10 time-of-flight sensors takes care of watching the display area for touch input gestures. It’s a fascinating project with a lot of potential, but we wonder how the variability of the human body might confound the display. Not to mention the need for short sleeves year round.

Need some basics on the micro-electrical mechanic systems (MEMS) behind the pico-projector in this watch? We’ve got a great primer on these microscopic machines.

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