Seeing The Truly Invisible With DIY Shortwave UV Imaging

July 6, 2016 by Donald Papp 19 Comments

We’ve all seen how to peel IR filters off digital cameras so they can see a little better in the dark, but there’s so much more to this next project than that. How about being able to see things normally completely outside the visual spectrum, like hydrogen combustion or electrical discharges?

[David Prutchi] has just shared his incredible work on making his own shortwave ultraviolet viewers for imaging entirely outside of the normal visible spectrum – in other words, seeing the truly invisible. The project has not only fascinating application examples, but provides detailed information about how to build two different imagers – complete with exact part numbers and sources.

If you’re thinking UV is a broad brush, you’re right. [David Prutchi] says he is most interested in Solar Blind UV (SBUV):

Solar radiation in the 240 nm to 280 nm range is completely absorbed by the ozone in the atmosphere and cannot reach Earth’s surface…

Without interference from background light, even very weak levels of UV are detectable. This allows ultraviolet-emitting phenomena (e.g. electrical discharges, hydrogen combustion, etc.) to be detectable in full daylight.

There is more to the process than simply slapping a UV filter onto a camera, but happily he addresses all the details and the information is also available as a PDF whitepaper. [David Prutchi] has been working with imaging for a long time, and with his sharing of detailed build plans and exact part numbers maybe others will get in on the fun. He’s also previously shared full build plans for a Raspberry Pi based multispectral imager, [David’s] DOLPHi Polarization Camera was a finalist in the 2015 Hackaday Prize, and he spoke at the Hackaday SuperConference about the usefulness of advanced imaging techniques for things like tissue analysis in medical procedures, and landmine detection for the purposes of cleaning up hazardous areas.

Improving 3D Printed Gears With… Hot Water

July 3, 2016 by Donald Papp 44 Comments

Being able to print out custom gears is one area where 3D printing can really shine, and [Karl Lew] has been busy doing exactly that with pinion gears printed in PLA and mounted to stepper motor shafts, but there are tradeoffs. Pinion gears need to grip a motor shaft tightly – normally done with a screw through the gear and onto the motor shaft. But a motor and its shaft can get quite warm when doing a lot of work, and a tight screw on a hot motor’s shaft will transmit that heat into the PLA, which can then deform.

[Karl Lew] managed to improve things in an unusual way: using a hot water bath to anneal the gear while it is attached to the stepper shaft. Annealing PLA has the effect of increasing the crystallinity of the material, which – according to an article going into some detail about the process of annealing PLA – increases stiffness, strength, and heat deflection. The annealing process also shrinks the part slightly, which happens to result in a very tight joint made between the gear and the slotted stepper shaft if the gear is annealed while connected to the motor.

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3D Printed Zoetrope Sculpture Squashes 4 Dimensions Into 3

June 29, 2016 by Donald Papp 46 Comments

This fascinating project manages to be both something new and something old done in a new way. Artist [Akinori Goto] has used 3D printing to create a sort of frameless zoetrope. It consists of a short animation of a human figure, but the 3D movements of that figure through time are “smeared” across a circular zone – instead of the movements of the figure being captured as individual figures or frames, they are combined into a single object, in a way squashing 4 dimensions into 3.

“Slices” of that object, when illuminated by a thin shaft of light, reveal the figure’s pose at a particular moment in time. When the object is spun while illuminated in this way, the figure appears to be animated in a manner very similar to a zoetrope.

There are two versions from [Akinori Goto] that we were able to find. The one shown above is a human figure walking, but there is a more recent and more ambitious version showing a dancer in motion, embedded below.

Since a thin ray of light is used to illuminate a single slice of the sculpture at a time, it’s also possible to use multiple points of illumination – or even move them – for different visual effects. Check out the videos below to see these in action.

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Homemade Smart Glasses Shows Why Smart Glasses Are Hard

June 26, 2016 by Donald Papp 13 Comments

[Harris Shallcross] decided to build a pair of smart glasses and recently completed a first prototype of his project ‘Ochi’ – an STM32 based, BLE-connected, OLED eyeglass display. There are of course several homebrew smart glasses projects out there; many are more polished-looking and nearly all of them also display information from a smartphone over Bluetooth. This one is interesting partly because it highlights many of the design challenges that smart glasses and other near-eye displays face. It also demonstrates the iterative development process: begin by getting something working to learn what does and doesn’t cut it at a basic level, and don’t optimize prematurely; let the process bring problems to the surface.

For his project, [Harris Shallcross] used a small 0.95″ diagonal 96×64 color OLED as the display. The lens is from a knockoff Google Cardboard headset, and is held in a 3D printed piece that slides along a wire rail to adjust focus. The display uses a custom font and is driven by an STM32 microcontroller on a small custom PCB, with an HM11 BLE module to receive data wirelessly. Power is provided by a rechargeable lithium-ion battery with a boost converter. An Android app handles sending small packets of data over Bluetooth for display. The prototype software handles display of time and date, calendar, BBC news feed, or weather information.

Devices like these have a lot to deal with. Weight and distribution of that weight is a concern, the size and comfort of the optics is important, and displaying data on a small OLED is only part of the battle – choosing what information to display and when are vital to the device being actually useful in any way, otherwise it’s just a tech demo.

This project set out to show whether it was possible to use the parts listed to make a glasses mounted smart display that was at least somewhat functional, and the software to support it. Clearly, [Harris Shallcross] succeeded at that, but what really showcases the development process is his list of improvements – what he decided needs to go into a second version, and why. One of those goals is to improve the optics; perhaps there’s something to learn from The $60 Bluetooth Head Mounted Display project, which used a similar OLED and a prism to locate the display off to the side instead of in front.

Autonomous Musical Soundscapes From 42 Fans And 7 Lasers

June 24, 2016 by Donald Papp 6 Comments

[dmitry] writes in to let us know about a new project that combines lasers with fans and turns the resulting modulation of the light beams into an autonomous soundscape. The piece is called “divider” and is a large, wall-mounted set of rails upon which seven red lasers are mounted on one end with seven matching light sensors mounted on the other end. Interrupting the lasers’ paths are forty-two brushless fans. Four Arduino Megas control the unit.

Laser beams shining into light sensors don’t do much of anything on their own, but when spinning fan blades interrupt each laser beam it modulates the solid beams and turns the readings of the sensors on the far end into a changing electrical signal which can be played as sound. Light being modulated by fan blades to create sound is the operating principle behind a Fan Synth, which we’ve discussed before as being a kind of siren (or you can go direct to that article’s fan synth demo video to hear what kind of sounds are possible from such a system.)

This project takes this entire concept of a fan synth further by not only increasing the number of lasers and fans, but by tying it all together into an autonomous system. The lasers are interrupted repeatedly and constantly, but never simultaneously. Listen to and watch it in action in the video below.

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Behold: Valve’s VR And AR Prototypes

June 22, 2016 by Donald Papp 16 Comments

Just in case anyone secretly had the idea that Valve Software’s VR and other hardware somehow sprang fully-formed from a lab, here are some great photos and video of early prototypes, and interviews with the people who made them. Some of the hardware is quite raw-looking, some of it is recognizable, and some are from directions that were explored but went nowhere, but it’s all fascinating.

ValvePrototypeVIsit-172-Medium — An early AR prototype that worked like looking through a tube into another world.

The accompanying video (embedded below) has some great background and stories about the research process, which began with a mandate to explore the concepts of AR and VR and determine what could be done and what was holding things back.

One good peek into this process is the piece of hardware shown to the left. You look into the lens end like a little telescope. It has a projector that beams an image directly into your eye, and it has camera-based tracking that updates that image extremely quickly.

The result is a device that lets you look through a little window into a completely different world. In the video (2:16) one of the developers says “It really taught us just how important tracking was. No matter [how you moved] it was essentially perfect. It was really the first glimpse we had into what could be achieved if you had very low persistence displays, and very good tracking.” That set the direction for the research that followed.

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CNC Upgrade To Guitar Pickup Winding Machine

June 18, 2016 by Donald Papp 34 Comments

The idea of winding inductive guitar pickups by hand is almost unthinkable. It uses extremely thin wire and is a repetitive, laborious process that nevertheless requires a certain amount of precision. It’s a prime candidate for automation, and while [Davide Gironi] did exactly that, he wasn’t entirely satisfied with his earlier version. He now has a new CNC version that is more full-featured and uses an ATMega8 microcontroller.

[Davide Gironi]’s previous version took care of winding and counting the number of turns, but it was still an assisted manual system that relied on a human operator. The new upgrade includes a number of features necessary to more fully automate the process, such as a wire tensioner, a wire guide and traverse mechanism (made from parts salvaged from a broken scanner), and an automatic stop for when the correct number of turns has been reached.

All kinds of small but significant details are covered in the build, such as using plastic and felt for anything that handles the wire — the extremely fine wire is insulated with a very thin coating and care must be taken to not scratch it off. Also, there is the need to compute how far the traverse mechanism must move the wire guide in order to place the new wire next to the previously-laid turn (taking into account the winding speed, which may be changing), and doing this smoothly so that the system does not need to speed up and slow down for every layer of winding.

This system is still programmed by hand using buttons and an LCD, but [Davide Gironi] says that the next version will use the UART in order to allow communication with (and configuration by) computer – opening the door to easy handling of multiple winding patterns. You can see video of the current version in action, below.

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