Budget Schlieren Imaging Setup Uses 3D Printing To Reveal The Unseen

April 17, 2025 by Tyler August 9 Comments

We’re suckers here for projects that let you see the unseeable, and [Ayden Wardell Aerospace] provides that on a budget with their $30 Schlieren Imaging Setup. The unseeable in question is differences in air density– or, more precisely, differences in the refractive index of the fluid the imaging set up makes use of, in this case air. Think of how you can see waves of “heat” on a warm day– that’s lower-density hot air refracting light as it rises. Schlieren photography takes advantage of this, allowing to analyze fluid flows– for example, the mach cones in a DIY rocket nozzle, which is what got [Ayden Wardell Aerospace] interested in the technique.

Shock diamonds from a homemade rocket nozzle imaged by this setup. — Examining exhaust makes this a useful tool for [Aerospace].

This is a ‘classic’ mirror-and-lamp Schlieren set up. You put the system you wish to film near the focal plane of a spherical mirror, and camera and light source out at twice the focal distance. Rays deflected by changes in refractive index miss the camera– usually one places a razor blade precisely to block them, but [Ayden] found that when using a smart phone that was unnecessary, which shocked this author.

While it is possible that [Ayden Wardell Aerospace] has technically constructed a shadowgraph, they claim that carefully positioning the smartphone allows the sharp edge of the case to replace the razor blade. A shadowgraph, which shows the second derivative of density, is a perfectly valid technique for flow visualization, and is superior to Schlieren photography in some circumstances– when looking at shock waves, for example.

Regardless, the great thing about this project is that [Ayden Wardell Aerospace] provides us with STLs for the mirror and smartphone mounting, as well as providing a BOM and a clear instructional video. Rather than arguing in the comments if this is “truly” Schlieren imaging, grab a mirror, extrude some filament, and test it for yourself!

There are many ways to do Schlieren images. We’ve highighted background-oriented techniques, and seen how to do it with a moiré pattern, or even a selfie stick. Still, this is the first time 3D printing has gotten involved and the build video below is quick and worth watching for those sweet, sweet Schlieren images. Continue reading “Budget Schlieren Imaging Setup Uses 3D Printing To Reveal The Unseen” →

Shine On You Crazy Diamond Quantum Magnetic Sensor

April 15, 2025 by Dan Maloney 21 Comments

We’re probably all familiar with the Hall Effect, at least to the extent that it can be used to make solid-state sensors for magnetic fields. It’s a cool bit of applied physics, but there are other ways to sense magnetic fields, including leveraging the weird world of quantum physics with this diamond, laser, and microwave open-source sensor.

Having never heard of quantum sensors before, we took the plunge and read up on the topic using some of the material provided by [Mark C] and his colleagues at Quantum Village. The gist of it seems to be that certain lab-grown diamonds can be manufactured with impurities such as nitrogen, which disrupt the normally very orderly lattice of carbon atoms and create a “nitrogen vacancy,” small pockets within the diamond with extra electrons. Shining a green laser on N-V diamonds can stimulate those electrons to jump up to higher energy states, releasing red light when they return to the ground state. Turning this into a sensor involves sweeping the N-V diamond with microwave energy in the presence of a magnetic field, which modifies which spin states of the electrons and hence how much red light is emitted.

Building a practical version of this quantum sensor isn’t as difficult as it sounds. The trickiest part seems to be building the diamond assembly, which has the N-V diamond — about the size of a grain of sand and actually not that expensive — potted in clear epoxy along with a loop of copper wire for the microwave antenna, a photodiode, and a small fleck of red filter material. The electronics primarily consist of an ADF4531 phase-locked loop RF signal generator and a 40-dB RF amplifier to generate the microwave signals, a green laser diode module, and an ESP32 dev board.

All the design files and firmware have been open-sourced, and everything about the build seems quite approachable. The write-up emphasizes Quantum Village’s desire to make this quantum technology’s “Apple II moment,” which we heartily endorse. We’ve seen N-V sensors detailed before, but this project might make it easier to play with quantum physics at home.

Building A DIY Tornado Tower

April 14, 2025 by Lewin Day 13 Comments

A tornado can be an awe-inspiring sight, but it can also flip your car, trash your house, and otherwise injure you with flying debris. If you’d like to look at swirling air currents in a safer context, you might appreciate this tornado tower build from [Gary Boyd].

[Gary]’s build was inspired by museum demonstrations and the tornado machine designs of [Harald Edens]. His build generates a vortex that spans 1 meter tall in a semi-open cylindrical chamber. A fan in the top of the device sucks in air from the chamber, and exhausts it through a vertical column of holes in the wall of the cylinder. This creates a vortex in the air, though it’s not something you can see on its own. To visualize the flow, the cylindrical chamber is also fitted with an ultrasonic mist generator in the base. The vortex in the chamber is able to pick up this mist, and it can be seen swirling upwards as it is sucked towards the fan at the top.

It’s a nice educational build, and one that’s as nice to look at as it is to study. It produces a thick white vortex that we’re sure someone could turn into an admirable lamp or clock or something, this being Hackaday, after all. In any case, vortexes are well worth your study. If you’re cooking up neat projects with this physical principle, you should absolutely let us know!

Plasmonic Modulators Directly Convert Terahertz Waves To Optical Signals

April 14, 2025 by Maya Posch 5 Comments

A major bottleneck with high-frequency wireless communications is the conversion from radio frequencies to optical signals and vice versa. This is performed by an electro-optic modulator (EOM), which generally are limited to GHz-level signals. To reach THz speeds, a new approach was needed, which researchers at ETH Zurich in Switzerland claim to have found in the form of a plasmonic phase modulator.

Although sounding like something from a Star Trek episode, plasmonics is a very real field, which involves the interaction between optical frequencies along metal-dielectric interfaces. The original 2015 paper by [Yannick Salamin] et al. as published in Nano Letters provides the foundations of the achievement, with the recent paper in Optica by [Yannik Horst] et al. covering the THz plasmonic EOM demonstration.

The demonstrated prototype can achieve 1.14 THz, though signal degradation begins to occur around 1 THz. This is achieved by using plasmons (quanta of electron oscillators) generated on the gold surface, who affect the optical beam as it passes small slots in the gold surface that contain a nonlinear organic electro optic material that ‘writes’ the original wireless signal onto the optical beam.

Creating A Somatosensory Pathway From Human Stem Cells

April 11, 2025 by Maya Posch No comments

Human biology is very much like that of other mammals, and yet so very different in areas where it matters. One of these being human neurology, with aspects like the human brain and the somatosensory pathways (i.e. touch etc.) being not only hard to study in non-human animal analogs, but also (genetically) different enough that a human test subject is required. Over the past years the use of human organoids have come into use, which are (parts of) organs grown from human pluripotent stem cells and thus allow for ethical human experimentation.

For studying aspects like the somatosensory pathways, multiple of such organoids must be combined, with recently [Ji-il Kim] et al. as published in Nature demonstrating the creation of a so-called assembloid. This four-part assembloid contains somatosensory, spinal, thalamic and cortical organoids, covering the entirety of such a pathway from e.g. one’s skin to the brain’s cortex where the sensory information is received.

Such assembloids are – much like organoids – extremely useful for not only studying biological and biochemical processes, but also to research diseases and disorders, including tactile deficits as previously studied in mouse models by e.g. [Lauren L. Orefice] et al. caused by certain genetic mutations in Mecp2 and other genes, as well as genes like SCN9A that can cause clinical absence of pain perception.

Using these assembloids the development of these pathways can be studied in great detail and therapies developed and tested.

You Shouldn’t Build An X-Ray Machine, But You Could

April 9, 2025 by Al Williams 18 Comments

Ever wanted your own X-ray machine? Of course you have! Many of us were indoctrinated with enticing ads for X-ray specs and if you like to see what’s inside things, what’s better than a machine that looks inside things? [Hyperspace Pirate] agrees, and he shows you the dangers of having your own X-ray machine in the video below.

The project starts with an X-ray tube and a high voltage supply. The tube takes around 70,000 volts which means you need a pretty stout supply, an interesting 3D printed resistor, and some mineral oil.

The output display? A normal camera. You also need an intensifying screen, which is just a screen with phosphor or something similar. He eventually puts everything in lead and reminds you that this is a very dangerous project and you should probably skip it unless you are certain you know how to deal with X-ray dangers.

Overall, looks like a fun project. But if you want real credit, do like [Harry Simmons] and blow your own X-ray tube, too. We see people build similar machines from time to time. You shouldn’t, but if you do, remember to be careful and to tell us about it!

Continue reading “You Shouldn’t Build An X-Ray Machine, But You Could” →

A Tale Of Nuclear Shenanigans From Down Under

April 6, 2025 by Jenny List 47 Comments

It’s likely that among the readers of this article there will be many who collect something. Whether it’s rare early LEDs or first-year-of-manufacture microprocessors, you’ll scour the internet to find them, and eagerly await mystery packages from the other side of the world.

There’s a tale emerging from Australia featuring just such a collector, whose collection now has him facing a jail sentence for importing plutonium. The story however is not so clear-cut, featuring a media frenzy and over-reaction from the authorities worthy of Gatwick Airport. [Explosions&Fire] has a rather long video unpacking the events, which we’ve placed below the break.

Emmanuel Lidden is an element collector, someone who tries to assemble an entire Periodic Table in their collection. He ordered a range of elements from an American element collectors’ supply website, including samples of plutonium and thorium. He seems to have been unaware he was committing any crime, with the microscopic samples available from legitimate websites with no warnings attached. The case becomes murkier as the Australian authorities flagged the thorium sample and instructed the courier not to deliver it, which they did anyway. Then a raid of the type you’d expect for the terrorists who stole the plutonium in Back To The Future was launched, along with that Gatwick-esque media frenzy.

We’re inclined to agree that the penalty likely to be meted out to him for buying a sliver of a Soviet smoke detector embedded in a Lucite cube seems overly steep, but at the same time his obvious naivety over dealing in radioactive materials marks him as perhaps more than a little foolhardy. It’s something over which to ponder though, have we managed to amass anything illegal disguised as outdated devices? Have you? Perhaps it’s something to discuss in the comments.

Continue reading “A Tale Of Nuclear Shenanigans From Down Under” →