We’ve all heard the “Do not stare into laser with remaining eye” joke. It’s funny because it’s true, as pretty much any laser a hobbyist can easily come by can cause permanent damage to eyes unless the proper precautions are taken. But a fiber laser with 200kW peak power is in another hazard class entirely.
Granted, outsized power ratings like this are a bit misleading, based as they are on femtosecond-long pulses. And to be sure, the fiber laser that [Marco Reps] tears down in the video below was as harmless as a kitten when he got it, thanks to its output optics having been unceremoniously shorn from the amplifier by its former owner. Reattaching the output and splicing the fiber would be necessary to get the laser lasing again, but [Marco] had other priorities in mind. He wanted to understand the operation of a fiber laser, but the tangle of fibers on two separate levels inside the chassis was somewhat inscrutable. The coils of fiber wrapped around the aluminum drums inside the chassis turned out to be the amplifier; fed by a semiconductor seed laser, the light pulse travels through the ytterbium-doped fiber of the two-stage amplifier, which is the active gain medium where stimulated emission, and therefore amplification, occurs.
With a little reverse engineering and the help of an online manual, he was able to understand the laser’s operation. A laser company helped him splice the optics back together – seeing the splicing rig in action is worth the price of admission alone – and the unit seems to be in more or less working order at this point. Normally the most powerful laser we see around here are the CO2 lasers in those cheap Chinese laser cutters, so we’re looking forward to learning more about fiber lasers.
Aside from frightening small children, we have absolutely no idea why anyone would need a face-magnifying headpiece. But the video below gives us a chuckle every time we see it, and we figure a good laugh that incorporates a quick optics hack is worth a look.
When he’s not playing geek in a box, [Curious Marc]’s videos usually have more of a retrocomputing theme, like his recent conversion of a vintage terminal to a character set from a made-up language, or helping to revive an Apollo Guidance Computer. Given gems like those, we were surprised to learn that [Marc]’s background is physics – optics, to be precise – and that he studied at École Polytechnique, the same school famed physicist Augustin-Jean Fresnel attended. Which fits right into this build since it features one of those large, plastic Fresnel lenses. After a fascinating detour into the history of Fresnel’s namesake lens, [Marc] proceeds with the build.
It’s simplicity itself – a box big enough to wear on the head with one end replaced by the Fresnel lens. A strip of LEDs – warm white, please, lest the wearer takes on a deathly pall – lines the edge of the box just behind the lens. If you want to get fancy, maybe attaching a hard-hat suspension piece would make it more wearable, but even as is it’s just a hoot to see someone with a magnified and distorted head walking around. One probably should be careful not to look at the sun while wearing this, however, for reasons that become apparent beginning at the 3:24 mark of the video.
Thanks to [Marc] for perhaps the oddest YouTube face-reveal yet, and for a great idea for a quick cosplay hack.
Miss your shot and scratch on the eight ball? It’s natural to blame the table for not being level so you can save face, but in all likelihood, you’re probably right. [Huygens Optics]’s father never misses a billiards shot on his home table, until one day he did. [Huygens Optics] rushed to his aid and built an extremely precise spirit level for the table so it will never happen again.
First and foremost, he had to decide how sensitive the spirit level should be. Obviously, the table should be as level as possible, though other factors like the condition of the felt will come into play as well. In doing some calculations, he found that every degree of leveling error in the table translates to several millimeters of ball unevenness and deviation, so he wanted the level to have .01 degrees of accuracy. How he manages this feat of grinding and polishing in a hobbyist workshop is all captured in the fascinating video after the break.
The level is made from two disks cut from leftover 15mm borosilicate glass. Between the disks is a 4mm cavity for the liquid (ethyl alcohol) and the air bubble to move around. To avoid introducing error with uneven adhesive application, [Huygens Optics] tried to join the disks using optical contact bonding, wherein two surfaces stick together through the magic of intermolecular forces, like the one that keeps geckos attached to vertical things. That worked quite well until he added the liquid, which broke the bond. Instead, he used a thin, UV-curable epoxy.
Honestly, we never wondered how those old film cameras used to put the date stamp in the lower right-hand corner of the frame. Luckily, [Ben Krasnow] does not suffer from this deplorable lack of curiosity, and his video teardown of a date-stamping film camera back (embedded below) not only answers the question, but provides a useful lesson in value engineering.
For the likely fair fraction of the audience who has never taken a photo on film before, cheap 35-mm cameras were once a big thing. They were really all one had for family snapshots and the like unless you wanted to invest in single-lens reflex cameras and all the lenses and accessories. They were miles better than earlier cartridge cameras like the 110 or – shudder – Disc film, and the cameras started getting some neat electronic features too. One was the little red-orange date stamp, which from the color we – and [Ben] assumed was some sort of LED pressed up against the film, but it ends up being much cooler than that.
Digging into the back of an old camera, [Ben] found that there’s actually a tiny projector that uses a mirror to fold the optical path between the film and a grain-of-wheat incandescent bulb. An LCD filter sits in the optical path, but because it’s not exactly on the plane of the film, it actually has to project the image onto the film. The incandescent bulb acts as a point source and the mirror makes the optical path long enough that the date stamp image appears sharp on the film. It’s cheap, readily adapted to other cameras, and reliable.
It seems like the physics of silicon long ago replaced the chemistry of silver as the primary means of creating photographs, to the point where few of us even have film cameras anymore, and home darkrooms are a relic of the deep past. Nobody doubts that the ability to snap a quick photo or even to create a work of photographic genius with a tiny device that fits in your pocket is a wonder of the world, but still, digital photographs can lack some of the soul of film photography.
Recapturing the look of old school photography is a passion for a relatively small group of dedicated photographers, who ply their craft with equipment and chemistries that haven’t been in widespread use for a hundred years. The tools of this specialty trade are hard to come by commercially, so practitioners of alternate photographic processes are by definition hackers, making current equipment bend to the old ways. Pierre-Loup is one such artist, working with collodion plates, hacked large-format cameras, pinholes camera, and chemicals and processes galore – anything that lets him capture a unique image. His photographs are eerie, with analog imperfections that Photoshop would have a hard time creating.
Join us as Pierre-Loup takes us on a tour through the world of alternative photography. We’ll look at the different chemistries used in alternative photography, the reasons why anyone would want to try it, and the equipment needed to pull it off. Photography was always a hack, until it wasn’t; Pierre-Loup will show us how he’s trying to put some soul back into it.
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VR headsets have been seeing new life for a few years now, and when it comes to head-mounted displays, the field of view (FOV) is one of the specs everyone’s keen to discover. Valve Software have published a highly technical yet accessibly-presented document that explains why Field of View (FOV) is a complex thing when it pertains to head-mounted displays. FOV is relatively simple when it comes to things such as cameras, but it gets much more complicated and hard to define or measure easily when it comes to using lenses to put images right up next to eyeballs.
The document goes into some useful detail about head-mounted displays in general, the design trade-offs, and naturally talks about the brand-new Valve Index VR headset in particular. The Index uses proprietary lenses combined with a slight outward cant to each eye’s display, and they explain precisely what benefits are gained from each design point. Eye relief (distance from eye to lens), lens shape and mounting (limiting how close the eye can physically get), and adjustability (because faces and eyes come in different configurations) all have a role to play. It’s a situation where every millimeter matters.
If there’s one main point Valve is trying to make with this document, it’s summed up as “it’s really hard to use a single number to effectively describe the field of view of an HMD.” They plan to publish additional information on the topics of modding as well as optics, so keep an eye out on their Valve Index Deep Dive publication list.
Some of biology’s most visually striking images come from fluorescence microscopes. Their brilliant colors on black look like a neon sign from an empty highway. A brand new fluorescence microscope is beyond a hacker’s budget and even beyond some labs’, but there are ways to upgrade an entry-level scope for the cost of a few cups of coffee. [Justin Atkin] of The Thought Emporium published a scope hacking video which can also be seen below. He is becoming a reputed scope modder.
This video assumes a couple of things for the $10 price tag. The first premise is that you already have a scope, a camera adapter, and a camera capable of shooting long exposures. The second premise is that you are willing to break the seals and open the scope to make some reversible mods. Since you are reading Hackaday, maybe that is a given.
The premise is simple compared to the build, which is not rocket surgery, the light source from below illuminates the subject like a raver, and the filter removes any light that isn’t spectacular before it gets to the camera.