Cannonball Mold Makes A Dandy Integrating Sphere For Laser Measurements

February 6, 2022 by Dan Maloney 9 Comments

It’s an age-old riddle: if you have a perfect sphere with a perfectly reflective inner surface, will light bounce around inside it forever? The answer is pretty obvious when you think it through, but that doesn’t mean that you can’t put the principle to use, as we see with this homemade Ulbricht sphere for optical measurements.

If you’ve never heard of an Ulbricht sphere, don’t worry — it’s also known as an integrating sphere, and that makes its function a little more apparent. As [Les Wright] explains, an integrating sphere is an optical element with a hollow spherical cavity that’s coated with a diffusely reflective coating. There are two ports in the sphere, one for admitting light — usually from a laser — and one for light to exit. The light bounces around inside the sphere and becomes perfectly diffuse, and creates a uniform beam at the exit port.

[Les]’ need for an integrating sphere comes from the desire to measure the output of some of his lasers with his Raspberry Pi-based PySpectrometer. Rather than shell out for an expensive commercial integrating sphere, or turn one on a lathe, [Les] turned to an unlikely source: cannonball molds. The inside of the mold was painted with an equally unlikely ultra-white paint concocted from barium sulfate and PVA glue. With a few ports machined into the mold, it works perfectly to diffuse the light from his dye lasers for proper measurements.

Lasers can be an expensive hobby, but [Les] always seems to find a way to make things more affordable and just as good. Whether it’s homemade doorknob caps for high-voltage power supplies or blasting the Bayer filter off a cheap CCD camera, he always seems to find a way.

Continue reading “Cannonball Mold Makes A Dandy Integrating Sphere For Laser Measurements” →

Two shots of the dispenser in question next to each other, showing it from different sides. One is showing the front panel, and the other shot gives us a better look at the top part, with a rotating disk that has openings for treats to be placed in.

Open-Hardware Dog Treat Dispenser Is A Stepping Stone For Behavioral Research

February 6, 2022 by Arya Voronova 13 Comments

The principles of open-source hardware are starting to make great strides in scientific research fields. [Walker Arce] tells us about his paper co-authored with [Jeffrey R. Stevens], about a dog treat dispenser designed with scientific researchers in mind – indispensable for behavior research purposes, and easily reproducible so that our science can be, too. Use of Raspberry Pi, NEMA steppers and a whole lot of 3D printed parts make this build cheap (< $200 USD) and easy to repeat for any experiments involving dogs or other treat-loving animals.

Even if you’re not a scientist, you could always build one for your own pet training purposes – this design is that simple and easy to reproduce! The majority of the parts are hobbyist-grade, and chances are, you can find most of the parts for this around your workshop. Wondering how this dispenser works, and most importantly, if the dogs are satisfied with it? Check out a short demonstration video after the break.

Despite such dispensers being commercially available, having a new kind of dispenser designed and verified is more valuable than you’d expect – authors report that, in their experience, off-the-shelf dispensers have 20-30% error rate while theirs can boast just 4%, and they have test results to back that up. We can’t help but be happy that the better-performing one is available for any of us to build. The GitHub repository has everything you could want – from STLs and PCB files, to a Raspberry Pi SD card image and a 14-page assembly and setup guide PDF.

Open hardware and science are a match made in heaven, even if the relationship is still developing. The Hackaday community has come together to discuss open hardware in science before, and every now and then, open-source scientific equipment graces our pages, just like this recent assortment of biosensing hacks using repurposed consumer-grade equipment.

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3D Printed Radiation Shields Get Put To The Test

February 4, 2022 by Tom Nardi 19 Comments

Don’t get too excited, a 3D printed radiation shield won’t keep you from getting irradiated during WWIII. But until the Doomsday Clock starts clanging its midnight bell, you can use one to improve the accuracy of your homebrew weather monitoring station by keeping the sun from heating up your temperature sensor. But how much does it help, and what material should you load up in your extruder to make one? Those questions, and more, are the topic of a fascinating whitepaper included in the upcoming volume of HardwareX.

Design and Implementation of 3-D Printed Radiation Shields for Environmental Sensors not only tests how effective these low-cost shields are when compared to an uncovered sensor, but addresses specific concerns in regards to leaving 3D printed parts out in the elements. Readers who’ve squirted out a few rolls worth of the stuff will know that common polylactic acid (PLA) filament, while easy to work with and affordable, isn’t known for its resilience. In fact, one of the advertised properties of the renewable plastic is that it’s biodegradable (theoretically, at least), so leaving it outside for any length of time sounds like it’s bound to go poorly.

PLA’s mechanical strength dropped rapidly.

To make a long story short, it does. While the team demonstrated that the PLA printed radiation shield absolutely helped preserve the accuracy of the temperature and humidity sensors mounted inside of it, the structure itself began to deform rapidly from UV exposure. Further tests determined that the mechanical strength of the PLA showed a notable reduction in as little as 30 days, and a sharp decline after 90 days.

Luckily, there was more than one plastic horse in the race. In addition to the PLA printed shield, the team also tested a version printed in acrylonitrile styrene acrylate (ASA) which fared far better. There was no visible deformation of the shield, and after 90 days, the reduction in mechanical strength was negligible. It even performed a bit better when it came to shielding the temperature sensor, which the team believes may be due to the material’s optical transmission properties.

So there you have it: a 3D printed radiation shield will absolutely improve the accuracy of your weather sensors, but if you want it to last outside, PLA just isn’t going to cut it. On the other hand, you could also save yourself a whole lot of time by just using a stack of plant saucers. Whatever works.

Thanks to [tahnok] for the tip.

As apples travel down the conveyor belt, they are scanned using InGaAs and CMOS cameras. The InGaAs camera will show defects beginning to form under the skin that a human eye cannot see; the CMOS camera will show visible defects. (Credit: Hamamatsu)

Shining A Different Light On Reality With Short-Wave Infrared Radiation

February 3, 2022 by Maya Posch 23 Comments

As great as cameras that operate in the visual light spectrum are, they omit a lot of the information that can be gleaned from other wavelengths. There is also the minor issue that visibility is often impacted, such as when it’s raining, or foggy. When this happens, applications such as self-driving cars which rely on this, have a major issue. Through the use of sensors that are sensitive to other wavelengths, we can however avoid many of these issues.

Short-wave infrared radiation (SWIR) is roughly the part of the electromagnetic spectrum between 1.4 μm – 3 μm, or 100 THz – 214 THz. This places it between visible light and microwaves, and above long-wave IR at 20 THz – 37 THz. LWIR is what thermal cameras use, with LWIR also emitted by warm objects, such as the human body.

SWIR is largely unaffected by water in the atmosphere, while also passing through materials that are opaque to visible light. This allowing SWIR to be used for the analysis and inspection of everything from PCBs and fruit to works of art to capture details that are otherwise invisible or very hard to see.

Unfortunately, much like thermal camera sensors, SWIR sensors are rather expensive. Or they were, until quite recently, with the emergence of quantum-dot-based sensors that significantly decrease the costs of these sensors.

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How The Hunga Tonga Volcano Eruption Was Felt Around The World

February 1, 2022 by Zoe Skyforest 14 Comments

On the 14th of January, 2022, the Hunga Tonga-Hunga Ha’apai volcano began a gigantic eruption that would go on to peak in ferocity the next day. The uninhabited island volcano would quickly make headlines as the country of Tonga was cut off the world and tsunamis bore out from the eurption zone.

In a volcanic event of this size, the effects can be felt around the world. With modern instruments, they can be properly understood too. Let’s take a look at how the effects of the Hunga Tonga eruption were captured and measured across the globe.

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Radio Amateurs & Skywatchers Rejoice, Sat Operators Worry: Solar Storm Incoming

February 1, 2022 by Jenny List 23 Comments

How do you look back over your life and divide it up? Maybe by decades, cultural moments, or geopolitical events. For radio amateurs with older callsigns there’s a temptation to do so by solar cycles, as the roughly 11-year period of the Sun’s activity had a huge effect on radio propagation through the charge it creates in the upper atmosphere. We’re now in solar cycle 25, numbered since the 18th century when the science of solar observation began, and as never before we’re surrounded by information from experts such as [Dr. Tamitha Skov], the so-called [Space Weather Woman]. When she says something is on the way we listen, so a recent Tweet predicting a direct hit from a solar storm with a good probability of auroras in lower latitudes is very much worth sharing.

We must extend our commiserations to readers in equatorial climes and ever through the lower half of the USA, southern Europe, the Middle East, India, Japan, and China. You won’t see the aurora we’ll catch in Europe along with our friends in New Zealand, Canada, Russia, and northern USA. But even then to those of us at moderate latitudes an aurora is a pretty rare event, so we’re hoping for clear skies on the 2nd of February and would advise you to look out too if you’re in the likely zone even if they won’t be quite as impressive as those in our header picture. Meanwhile radio amateurs everywhere don’t have to see pretty lights in the sky to reap the benefits in terms of propagation, so happy DX hunting! The Tweet is embedded below the break, so you can play the timeline for yourselves.

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Simple Setup Answers Complex Question On The Physics Of Solids

February 1, 2022 by Dan Maloney 17 Comments

Thought experiments can be extremely powerful; after all, pretty much everything that [Einstein] came up with was based on thought experiments. But when a thought experiment turns into a real experiment, that’s when things can get really interesting, and where unexpected insights crop up.

Take [AlphaPhoenix]’s simple question: “Are solid objects really solid?” On the face of it, this seems like a silly and trivial question, but the thought experiment he presents reveals more. He posits that pushing on one end of a solid metal rod a meter or so in length will result in motion at the other end of the rod pretty much instantly. But what if we scale that rod up considerably — say, to one light-second in length. Is a displacement at one end of the rob instantly apparent at the other end? It’s a bit of a mind-boggler.

To answer the question, [AlphaPhoneix] set up a simple experiment with the aforementioned steel rod — the shorter one, of course. The test setup was pretty clever: a piezoelectric sensor at one end of the bar, and a hammer wired to a battery at the other end, to sense when the hammer made contact with the bar. Both sensors were connected to an oscilloscope to set up to capture the pulses and measure the time. It turned out that the test setup was quite a challenge to get right, and troubleshooting the rig took him down a rabbit hole that was just as interesting as answering the original question. We won’t spoil the ending, but suffice it to say we were pleased that our first instinct turned out to be correct, even if for the wrong reasons.

If you haven’t checked out [AlphaPhoenix] yet, you really should. With a doctorate in material science, he’s got an interesting outlook on things, like calculating pi using raindrops or keeping the “ultra” in ultra-high vacuum. Continue reading “Simple Setup Answers Complex Question On The Physics Of Solids” →