19th Century Photography In Extreme Miniature

Ever since the invention of the microscope, humanity has gained access to the world of the incredibly small. Scientists discovered that creatures never known to exist before are alive in an uncountable number in spaces as small as the head of a pin. But the microscope unlocked some interesting forms of art as well. Not only could people view and photograph small objects with them, but in the mid-nineteenth century, various artists and scientists used them to shrink photographs themselves down into the world of the microscopic. This article goes into depth on how one man from this era invented the art form known as microphotography.

Compared to photomicroscopy, which uses a microscope or other similar optical device to take normal-sized photographs of incredibly small things, microphotography takes the reverse approach of taking pictures of normal-sized things and shrinking them down to small sizes. [John Benjamin Dancer] was the inventor of this method, which used optics to shrink an image to a small size. The pictures were developed onto photosensitive media just like normal-sized photographs. Not only were these unique pieces of art, which developed — no pun intended — into a large fad, but they also had plenty of other uses as well. For example, since the photographs weren’t at all obvious without a microscope, they found plenty of uses in espionage and erotica.

Although the uses for microphotography have declined in today’s digital world, there are still plenty of unique pieces of art around with these minuscule photographs, as well as a bustling collector culture around preserving some of the antique and historical microphotographs from before the turn of the century. There is also similar technology, like microfilm and microfiche, that were generally used to preserve data instead of creating art, although plenty of these are being converted to digital information storage now.

Projector on left with red arrow pointing towards object, another red arrow points towards a piece of paper and then camera.

Pictures From Paper Reflections And A Single Pixel

Taking a picture with a single photoresistor is a brain-breaking idea. But go deeper and imagine taking that same picture with the same photoresistor, but without even facing the object. [Jon Bumstead] did exactly that with compressed sensing and a projector. Incredibly, the resulting image is from the perspective of the projector, not the “camera”.

This camera setup is very similar to one we’ve seen before, but far more capable. The only required electronics are a small projector and a single photodiode. The secret sauce in this particular design lies in the pattern projected and the algorithm to parse the data.

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Close up of a custom optical HDMI cable on a desk

Let There Be Light: The Engineering Of Optical HDMI

In a recent video, [Shahriar] from The Signal Path has unveiled the intricate design and architecture of optical HDMI cables, offering a cost-effective solution to extend HDMI 2.0 connections beyond the limitations of traditional copper links. This exploration is particularly captivating for those passionate about innovative hardware hacks and signal transmission technologies.

[Shahriar] begins by dissecting the fundamentals of HDMI high-speed data transmission, focusing on the Transition Minimized Differential Signaling (TMDS) standard. He then transitions to the challenges of converting from twisted-pair copper to optical lanes, emphasizing the pivotal roles of Vertical-Cavity Surface-Emitting Lasers (VCSELs) and PIN photodiodes. These components are essential for transforming electrical signals into optical ones and vice versa, enabling data transmission over greater distances without significant signal degradation.

A standout aspect of this teardown is the detailed examination of the optical modules, highlighting the use of free-space optics and optical confinement techniques with lasers and detectors. [Shahriar] captures the eye diagram of the received high-speed lane and confirms the VCSELs’ optical wavelength at 850 nm. Additionally, he provides a microscopic inspection of the TX and RX chips, revealing the intricate VCSEL and photodetector arrays. His thorough analysis offers invaluable insights into the electronic architecture of optical HDMI cables, shedding light on the complexities of signal integrity and the innovative solutions employed to overcome them.

For enthusiasts eager to take a deeper look into the nuances of optical HDMI technology, [Shahriar]’s comprehensive teardown serves as an excellent resource. It not only gives an insight in the components and design choices involved, but also inspires further exploration into enhancing data transmission methods.

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A Waist Level Viewfinder For Not A Lot

Photographic accessories are often plagued by high prices, as photography is considered a rich man’s game. It doesn’t have to be that way though, and [Snappiness] is here to get you started on the route to cheaper kit with a waist-level viewfinder project.

If you’ve used a twin-lens reflex camera then you should be familiar with a waist level viewfinder, it’s a lens and mirror arrangement allowing the photographer to frame the shot looking down from above. Modern cameras often have no viewfinder, so this is aimed at digital compacts without flip-up screens.

It has three components, all available for relatively low prices, and mounted in a 3D printed case. There’s a prime lens, a mirror, and a Fresnel lens forming the part the photographer looks through. It’s a simple device, but still one which would cost a lot more off the shelf. The video is below the break.

It might interest you to know that this is not the first viewfinder project we’ve brought you for digital cameras.

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Schematic of quantum measurement basis on whiteboard

Shedding Light On Quantum Measurement With Calcite

Have you ever struggled with the concept of quantum measurement, feeling it’s unnecessarily abstract? You’re not alone. Enter this guide by [Mithuna] from Looking Glass Universe, where she circles back on the concept of  measurement basis in quantum mechanics using a rather simple piece of calcite crystal. We wrote about similar endeavours in reflection on Shanni Prutchi’s talk at the Hackaday SuperConference in 2015. If that memory got a bit dusty in your mind, here’s a quick course to make things click again.

In essence, calcite splits a beam of light into two dots based on polarization. By aligning filters and rotating angles, you can observe how light behaves when forced into ‘choices’. The dots you see are a direct representation of the light’s polarization states. Now this isn’t just a neat trick for photons; it’s a practical window into the probability-driven nature of quantum systems.

Even with just one photon passing through per second, the calcite setup demonstrates how light ‘chooses’ a path, revealing the probabilistic essence of quantum mechanics. Using common materials (laser pointers, polarizing filters, and calcite), anyone can reproduce this experiment at home.

If this sparks curiosity, explore Hackaday’s archives for quantum mechanics. Or just find yourself a good slice of calcite online, steal the laser pointer from your cat’s toy bin, and get going!

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Innovative Clock Uses Printed Caustic Lens

Hackers and makers have built just about every kind of clock under the sun. Digital, analog, seven-segment, mechanical seven-segment, binary, ternary, hexadecimal… you name it. It’s been done. You really have to try to find something that shocks us… something we haven’t seen before. [Moritz v. Sivers] has done just that. 

Wild. Just wild.

Meet the Caustic Clock. It’s based on the innovative Hollow Clock from [shiura]. It displays time with an hour hand and a minute hand, and that’s all so conventional. But what really caught our eye was the manner in which its dial works. It uses caustics to display the clock dial on a wall as light shines through it.

If you’ve ever seen sunlight reflect through a glass, or the dancing patterns in an outdoor swimming pool, you’ve seen caustics at play. Caustics are the bright patterns we see projected through a transparent object, and if you shape that object properly, you can control them. In this case, [Moritz] used some GitHub code from [Matt Ferraro] to create a caustic projection clockface, and 3D printed it using an SLA printer.

The rest of the clock is straightforward enough—there’s some WS2812 LEDs involved, an Arduino Nano, and even an RP2040. But the real magic is in the light show and how it’s all achieved. We love learning about optics, and this is a beautiful effect well worth studying yourself.

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Flashlight shining through gold leaf on glass

Shining Through: Germanium And Gold Leaf Transparency

Germanium. It might sound like just another periodic table entry (number 32, to be exact), but in the world of infrared light, it’s anything but ordinary. A recent video by [The Action Lab] dives into the fascinating property of germanium being transparent to infrared light. This might sound like sci-fi jargon, but it’s a real phenomenon that can be easily demonstrated with nothing more than a flashlight and a germanium coin. If you want to see how that looks, watch the video on how it’s done.

The fun doesn’t stop at germanium. In experiments, thin layers of gold—yes, the real deal—allowed visible light to shine through, provided the metal was reduced to a thickness of 100 nanometers (or: gold leaf). These hacks reveal something incredible: light interacts with materials in ways we don’t normally observe.

For instance, infrared light, with its lower energy, can pass through germanium, while visible light cannot. And while solid gold might seem impenetrable, its ultra-thin form becomes translucent, demonstrating the delicate dance of electromagnetic waves and electrons.

The implications of these discoveries aren’t just academic. From infrared cameras to optics used in space exploration, understanding these interactions has unlocked breakthroughs in technology. Has this article inspired you to craft something new? Or have you explored an effect similar to this? Let us know in the comments!

We usually take our germanium in the form of a diode. Or, maybe, a transistor.

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