500 Lasers Are Not Necessarily Better Than One, But They Look Great

If playing with but a single laser pointer is fun, then playing with 500 laser pointers must be 500 times the fun, right? So by extension, training 500 laser pointers on a single point must be the pinnacle of pointless mirth. And indeed it is.

When we first spotted this project, we thought for sure it was yet another case of lockdown-induced  boredom producing an over-the-top build. Mind you, we have no problem with that, but in this case, [nanoslavic] relates that this is actually a project from a few years back. It’s really as simple as it looks: 500 laser pointer modules arranged on a plate with a grid of holes in a 25 by 20 array. As he placed the laser modules on the board with a glob of hot glue, he carefully aimed each one to hit a single point about a meter and a half away.  There are also a handful of blue LEDs nestled into the array, because what project is complete without blue LEDs?

The modules are wired in concentric circuits and controlled by a simple bank of toggle switches. Alas, 500 converging 150-mW 5 mW lasers do not a 75-W 2.5 W laser make; when fully powered, the effect at the focal point is reported to be only a bit warm. But it looks incredible, especially through smoke. Throwing mirrors and lenses into the beam results in some interesting patterns, too.

You’ll still need to take safety seriously if you build something like this, of course, but this one is really just for show. If you’re really serious about doing some damage with lasers, check out the long list of inadvisable laser builds that [Styropyro] has accumulated — from a high-powered “lightsaber” to a 200-Watt laser bazooka.

(Terminate your beams carefully, folks. We don’t want anyone going blind.)

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Milling Dies And Injection Moulding Some Acrylic Lenses

[Zach] over at his channel Breaking Taps has put up an extraordinary account on manufacturing some homemade acrylic lenses. In the end, not only does he produce some beautiful concave lenses, he also covers the complete manufacturing process, from milling the aluminium die used for injection moulding to tweaking the parameters associated with injecting the actual acrylic, he even goes over the limitations of optics produced in this fashion.

What caught our eye in particular, was how [Zach] used the finished product to practically demonstrate photoelasticity originating from the stress induced by the moulding process. You might be familiar with describing the optical properties of a material by a single number, i.e its permittivity. But what happens if in addition to altering speed, the material also alters the polarisation and direction of light depending on the stress distribution within the material? Whilst a quantitative answer gets a bit complicated you can check out [Zach’s] additional videos to visualise the answer in a pretty and colourful way, without resorting to fancy computer simulations! If however, you really want to persist with the simulation route, check out our article on stress analysis in a totally different setting using Finite Element Analysis.

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This Camera Captures Piezo Inkjet Micro-Drops For DIY Microfluidics

In microfluidics, there are “drop on demand” instruments to precisely deposit extremely small volumes (pico- or nano-liters) of fluid. These devices are prohibitively expensive, so [Kyle] set out to design a system using hobbyist-level parts for under $1000. As part of this, he has a fascinating use case for a specialized camera: capturing the formation and shape of a micro-drop as it is made.

There are so many different parts to this effort that it’s all worth a read, but the two big design elements come down to:

  1. Making the microdrop using a piezo element
  2. Ensuring the drop is made correctly, and visually troubleshooting

Working prototype. The piezo tube is inside the blue piece at the top. The camera is to the right, and the LED strobe is on the left.

It’s one thing to make an inkjet element in a printer work, but it’s quite another to make a piezoelectric element dispense arbitrary liquids in a controlled, repeatable, and predictable way. Because piezoelectric elements force liquid out with a mechanical motion, different liquids require different drive signals and that kind of experimentation requires a way to see what is going on, hence the need for a drop observation camera.

[Kyle] ended up taking the lens assembly from a cheap USB microscope and mating it to his Korukesu C1 USB Camera with a 3D printed assembly. Another 3D printed enclosure doubles as a lightbox, holding the piezo tube in the center with the LED strobe and camera on opposite sides. The whole assembly had a few false starts, but in the end [Kyle] seems pretty happy with his results. The device is briefly described at a high level here. There are some rough edges, but it’s a working system.

Inkjet technology has been around for a long time (you can see a thirty-plus year old inkjet printer in action here) but it’s worth mentioning that not all inkjet heads are alike. Most inkjet printer heads operate thermally, which means a flash of heat vaporizes some ink to expel a micro-drop. These heads aren’t very suitable for microfluidics because not only do they rely on vaporizing the liquid, but they also don’t work well with anything other than the ink they’re designed for. Piezoelectric print heads are less common, but are more suited to the kind of work [Kyle] is doing.

[Ben Krasnow] Rolls Old School Camera Out For Photolithography

In a time when cameras have been reduced to microchips, it’s ironic that the old view camera, with its bellows and black cloth draped over the viewscreen for focusing, endures as an icon for photography. Such technology appears dated and with no application in the modern world, but as [Ben Krasnow] shows us, an old view camera is just the thing when you want to make homemade microchips. (Video, embedded below.)

Granted, the photolithography process [Ben] demonstrates in the video below is quite a bit upstream from the creation of chips. But mastering the process on a larger scale is a step on the way. The idea is to create a high-resolution photograph of a pattern — [Ben] chose both a test pattern and, in a nod to the season, an IRS tax form — that can be used as a mask. The camera he chose is a 4×5 view camera, the kind with lens and film connected by adjustable bellows. He found that modifications were needed to keep the film fixed at the focal plane, so he added a vacuum port to the film pack to suck the film flat. Developing film has always been magical, and watching the latent images appear on the film under the red light of the darkroom really brings us back — we can practically smell the vinegary stop solution.

[Ben] also steps through the rest of the photolithography process — spin coating glass slides with photoresist, making a contact print of the negative under UV light, developing the print, and sputtering it with titanium. It’s a fascinating process, and the fact that [Ben] mentions both garage chip-maker [Sam Zeloof] and [Justin Atkin] from the Thought Emporium means that three of our favorite YouTube mad scientists are collaborating. The possibilities are endless.

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Hackaday Links: March 22, 2020

Within the span of just two months, our world of unimaginable plenty and ready access to goods manufactured across the globe has been transformed into one where the bare essentials of life are hard to find at any price. The people on the frontline of the battle against COVID-19 are suffering supply chain pinches too, often at great risk to their health. Lack of proper personal protective equipment (PPE), especially face masks, is an acute problem, and the shortage will only exacerbate the problem as healthcare workers go down for the count. Factories are gearing up to make more masks, but in the meantime, the maker and hacker community can pitch in. FreeSewing, an open-source repository of sewing patterns, has a pattern for a simple face mask called the Fu that can be made quickly by an experienced threadworker. Efficacy of the masks made with that pattern will vary based on the materials used, obviously; a slightly less ad hoc effort is the 100 Million Mask Challenge, where volunteers are given a pattern and enough lab-tested materials to make 100 face masks. If you know how to sew, getting involved might make a difference.

As people around the world wrap their heads around the new normal of social distancing and the loss of human contact, there’s been an understandable spike in interest in amateur radio. QRZ.com reports that the FCC has recorded an uptick in the number of amateur radio licenses issued since the COVID-19 outbreak, and license test prep site HamRadioPrep.com has been swamped by new users seeking to prepare for taking the test. As we’ve discussed, the barrier for entry to ham radio is normally very low, both in terms of getting your license and getting the minimal equipment needed to get on the air. One hurdle aspiring hams might face is the cancellation of so-called VE testing, where Volunteer Examiners administer the written tests needed for each license class. Finding a face-to-face VE testing session now might be hard, but the VEs are likely to find a way to adapt. After all, hams were social distancing before social distancing was cool.

The list of public events that have been postponed or outright canceled by this pandemic is long indeed, with pretty much everything expected to draw more than a handful of people put into limbo. The hacking world is not immune, of course, with many high-profile events scuttled. But we hackers are a resourceful bunch, and the 10th annual Open Source Hardware Summit managed to go off on schedule as a virtual meeting last week. You can watch the nearly eight-hour livestream while you’re self-isolating. We’re confident that other conferences will go virtual in the near-term too rather than cancel outright.

And finally, if you’re sick of pandemic news and just want some escapist engineering eye candy, you could do worse than checking out what it takes to make a DSLR camera waterproof. We’ve honestly always numbered cameras as among the very least waterproof devices, but it turns out that photojournalists and filmmakers are pretty rough on their gear and expect it to keep working even so. The story here focuses (sorry) on Olympus cameras and lenses, which you’ll note that Takasu-san only ever refers to as “splash-proof”, and the complex system of O-rings and seals needed to keep water away from their innards. For our money, the best part was learning that lenses that have to change their internal volume, like zoom lenses, need to be vented so that air can move in and out. The engineering needed to keep water out of a vented system like that is pretty impressive.

Macro Photography With Industrial Lenses

Line scan cameras are advanced devices used for process inspection tasks in industrial applications. Used to monitor the quality of silicon wafers and other high-accuracy tasks, they’re often outfitted with top-quality optics that are highly specialised. [Peter] was able to get his hands on a lens for a line-scan camera, and decided to put it to work on some macro photography instead.

Macro image taken with the hacked lens.

Judging by the specs found online, this is a fairly serious piece of kit. It easily competes with top-shelf commercial optics, which is what piqued [Peter]’s interest in the part. Being such a specialised piece of hardware, you can’t just cruise over to eBay for an off-the-shelf adapter. Instead, a long chain of parts were used to affix this lens to a Sony AIII DSLR, converting from threaded fittings to a Nikon mount and then finally to Sony NEX mount.

Further work involved fitting an aperture into the chain to get the lens as close as possible to telecentric. This improves the lens’s performance for certain tasks, and makes focus stacking macro shots more readily achievable – something we’ve seen [Peter] tinker with before.

You never know what you might find when sorting through surplus industrial gear, could could score some high-performance hardware if you know where to look. It’s always great to see a cheap find become a useful instrument in the hacker toolbox!

Image Sensor From Discrete Parts Delivers Glorious 1-Kilopixel Images

Chances are pretty good that you have at least one digital image sensor somewhere close to you at this moment, likely within arm’s reach. The ubiquity of digital cameras is due to how cheap these sensors have become, and how easy they are to integrate into all sorts of devices. So why in the world would someone want to build an image sensor from discrete parts that’s 12,000 times worse than the average smartphone camera? Because, why not?

[Sean Hodgins] originally started this project as a digital pinhole camera, which is why it was called “digiObscura.” The idea was to build a 32×32 array of photosensors and focus light on it using only a pinhole, but that proved optically difficult as the small aperture greatly reduced the amount of light striking the array. The sensor, though, is where the interesting stuff is. [Sean] soldered 1,024 ALS-PT19 surface-mount phototransistors to the custom PCB along with two 32-bit analog multiplexers. The multiplexers are driven by a microcontroller to select each pixel in turn, one row and one column at a time. It takes a full five seconds to scan the array, so taking a picture hearkens back to the long exposures common in the early days of photography. And sure, it’s only a 1-kilopixel image, but it works.

[Sean] has had this project cooking for a while – in fact, the multiplexers he used for the camera came up as a separate project back in 2018. We’re glad to see that he got the rest built, even with the recycled lens he used. One wonders how a 3D-printed lens would work in front of that sensor.

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