The Trinket Contest has drawn to a close, but we’re still going to show off the entries that were received by the deadline. The contest asked you slap the Hackaday logo onto something for a chance at winning one of 20 Trinket dev boards donated by Adafruit. See a dozen of them shown off after the break.
Typically, when we want to take images, we use an image sensor paired with some sort of lens assembly to make a picture that’s sharply in focus. However, [okooptics] is here to show us there’s another way—using Scotch tape in place of a typical lens element.
If you just put Scotch tape over an image sensor without a lens, you’ll just get a blurry image, whatever you point it at. With the right algorithms, though, it’s possible to recover an image from that mess, using special “lensless imaging” techniques. In particular, [okooptics] shows how to recreate the so-called coded aperture techniques which were previously demonstrated in [Laura Waller]’s DiffuserCam paper.
It’s complicated stuff, but the video does a great job of breaking down the optics into understandable chunks. Armed with a Raspberry Pi HQ camera covered in a small amount of Scotch and electrical tape, [okooptics] is able to reconstruct a viable image from what initially looks like a blurry mess of nothingness, with the aid of the right deconvolution maths. It’s all about understanding the point spread function of the tape versus a regular lens, and figuring out how to fight off noise when reconstructing the image.
We’ve featured previous work from [okooptics] before, too, like this impressive demonstration of light transport and reconstruction. Video after the break.
Continue reading “Taking Photos With Scotch Tape Instead Of A Lens”
You’ve likely seen an X-cube, a dichroic prism used to split light into its constituent colours–you know, those fun little cubes you get when tearing apart a broken projector. Have you considered that the X-cube need not be a cube for its entire existence? [Matt] at “Matt’s Corner of Gem Cutting” on YouTube absolutely did, which is why he ground one into a 216-facet disco ball.
That’s the hack, really. He took something many of us have played with at our desks thinking “I should do something cool with this” and… did something cool with it that most of us lack the tools and especially skills to even consider. It’s not especially practical, but it is especially pretty. Art, in other words.
The shape he’s using is known specifically to gemologists as “Santa’s Little Helper II” though we’d probably describe it as a kind of isosphere. Faceting the cube is just a matter of grinding down the facets to create the isosphere, then polishing them to brilliance with increasingly finer grit. This is done one hemisphere at a time, so the other hemisphere can be safely held in place with the now-classic cyanoacrylate and baking soda composite. Yes, jewelers use that trick, too.
We were slightly worried when [Matt] dumped his finished disco ball in acetone to clean off the cyanoacrylate– we haven’t the foggiest idea what optical-quality glue is used to hold the four prisms of an X-cube together and were a little worried acetone might soften the joints. That turned out not to be an issue, and [Matt] now has the most eye-catching sun-catcher we think we’ve ever seen.
We actually have seen suncatchers before, though admittedly it’s not a very popular tag around here. The closest build to this one was a so-called “hypercrystal” that combined an infinitiy mirror with a crystaline shape and dicloric tape for an effect as trippy as it sounds.
We also featured a deep-dive a while back if you want to know how these colourful, hard-to-pronounce coatings work.
How do you go about making a mirror with 128 segments, each of which can be independently angled? That was the question that a certain bloke over at [Time Sink Studio] found himself pondering on, to ultimately settle on a whole batch of mini-actuators bought through AliExpress. These stepper-based actuators appear to be akin to those used with certain Oppo smartphones with pop-up camera, costing less than half a dollar for a very compact and quite fast actuator.
The basic design is very much akin to a macro version of a micromirror device, as used in e.g. DLP projectors, which rely on a kinetic mirror mount to enable precise alignment. With the small actuators travelling up to 8 mm each, the mirrors can cover 73 mm at a distance of 4 meters from a wall.
With the required angle of the mirror being effectively just the application of the Pythagorean theorem, the biggest challenge was probably calibrating these linear motors. Since they’re open loop devices, they are zeroed much like the steppers on 3D printers, by finding the end limit and counting steps from that known point. This doesn’t make drift impossible, but for projecting light onto walls it’s clearly more than good enough.
Continue reading “How To Use Tiny Open Loop Actuators For A Living Mirror”
Recently the avid teardown folk over at iFixit got their paws on Meta’s Ray-Ban Display glasses, for a literal in-depth look at these smart glasses. Along the way they came across the fascinating geometric waveguide technology that makes the floating display feature work so well. There’s also an accompanying video of the entire teardown, for those who enjoy watching a metal box cutter get jammed into plastic.
Overall, these smart glasses can be considered to be somewhat repairable, as you can pry the arms open with a bit of heat. Inside you’ll find the 960 mWh battery and a handful of PCBs, but finding spare parts for anything beyond perhaps the battery will be a challenge. The front part of the glasses contain the antennae and the special lens on the right side that works with the liquid crystal on silicon (LCoS) projector to reflect the image back to your eye.
While LCoS has been used for many years already, including Google Glass, it’s the glass that provides the biggest technological advancement. Instead of the typical diffractive waveguide it uses a geometric reflective waveguide made by Schott, with the technology developed by Lumus for use in augmented reality (AR) applications. This is supposed to offer better optical efficiency, as well as less light leakage into or out of the waveguide.
Although definitely impressive technology, the overall repairability score of these smart glasses is pretty low, and you have to contest with both looking incredibly dorky and some people considering you to be a bit of a glasshole.
Continue reading “The Fascinating Waveguide Technology Inside Meta’s Ray-Ban Display Glasses”
The concept of a 3D scanner can seem rather simple in theory: simply point a camera at the physical object you wish to scan in, rotate around the object to capture all angles and stitch it together into a 3D model along with textures created from the same photos. This photogrammetry application is definitely viable, but also limited in the sense that you’re relying on inferring three-dimensional parameters from a set of 2D images and rely on suitable lighting.
To get more detailed depth information from a scene you’d need to perform direct measurements, which can be done physically or through e.g. time-of-flight (ToF) measurements. Since contact-free ways of measurements tend to be often preferred, ToF makes a lot of sense, but comes with the disadvantage of measuring of only a single spot at a time. When the target is actively moving, you can fall back on photogrammetry or use an approach called structured-light (SL) scanning.
SL is what consumer electronics like the Microsoft Kinect popularized, using the combination of a visible and near-infrared (NIR) camera to record a pattern projected onto the subject, which is similar to how e.g. face-based login systems like Apple’s Face ID work. Considering how often Kinects have been used for generic purpose 3D scanners, this raises many questions regarding today’s crop of consumer 3D scanners, such as whether they’re all just basically Kinect-clones.
Continue reading “On 3D Scanners And Giving Kinects A New Purpose In Life”
Until the 2000s vacuum tubes practically ruled the roost. Even if they had surrendered practically fully to semiconductor technology like integrated circuits, there was no escaping them in everything from displays to video cameras. Until CMOS sensor technology became practical, proper video cameras used video camera tubes and well into the 2000s you’d generally scoff at those newfangled LC displays as they couldn’t capture the image quality of a decent CRT TV or monitor.
For a while it seemed that LCDs might indeed be just a flash in the pan, as it saw itself competing not just with old-school CRTs, but also its purported successors in the form of SED and FED in particular, while plasma TVs made home cinema go nuts for a long while with sizes, fast response times and black levels worth their high sale prices.
We all know now that LCDs survived, along with the newcomer in OLED displays, but despite this CRTs do not feel like something we truly left behind. Along with a retro computing revival, there’s an increasing level of interest in old-school CRTs to the point where people are actively prowling for used CRTs and the discontent with LCDs and OLED is clear with people longing for futuristic technologies like MicroLED and QD displays to fix all that’s wrong with today’s displays.
Could the return of CRTs be nigh in some kind of format?
Continue reading “The Impending CRT Display Revival Will Be Televised”
