Acoustic lenses are remarkable devices that just got cooler. A recent presentation at SIGGRAPH 2019 showed that with the help of 3D printing, it is possible to build the acoustic equivalent of optical devices. That is to say, configurations that redirect or focus sound waves. One fascinating demonstration worked like an acoustic prism, able to send different notes from a simple melody in different directions. Another was a device that dynamically varied the distance between two lenses in order to focus sound onto a moving target. In both cases, the sounds originate from an ordinary speaker and are shaped by passing through the acoustic lens or lenses, which are entirely passive devices.
Researchers from the University of Sussex used 3D printing for a modular approach to acoustic lens design. 16 different pre-printed “bricks” (shown here) can be assembled in various combinations to get different results. There are limitations, however. The demonstration lenses only work in a narrow bandwidth, meaning that the sound they work with is limited to about an octave at best. That’s enough for a simple melody, but not nearly enough to cover a human’s full audible range. Download the PDF for a quick read about the details, it’s only two pages but loaded with enough to whet your appetite to know more.
Directional sound can be done in other ways as well, such as using an array of ultrasonic emitters to create a coherent beam of sound. Ultrasonic emitters can even levitate lightweight objects. Ain’t sound neat?
Macro photography — the art of taking pictures of tiny things — can be an expensive pastime. Good lenses aren’t cheap, and greater magnification inflates the price even further. One way to release a bit more performance from your optics comes in the form of an extension tube, which mounts your lens further from the camera to zoom in a little on the image. Back in the day with a film SLR you could make a rough and ready tube with cardboard and tape, but in the age of the digital camera the lens has become as much a computer peripheral as an optical device. [Nicholas Sherlock] has solved this problem by creating a 3D-printed extension tube for his Canon that preserves connections between camera and lens.
More details of this 300mm monster’s construction go so far beyond a plastic tub formed of two threaded sections with adapter plates at the ends. He’s using off-the-shelf metal rings to fit camera and lens just right, but making the electronic contacts is where it gets interesting. On end uses pogo pins, the other provides a contact block made of nail heads. In both cases the 3D-printed parts are designed to provide mounting points for the pins and nails. The assembly technique is worth a look both because of the design and as an example of how to document all the juicy details we’re constantly looking for in a great hack.
The results speak for themselves, in that the photography provides an impressive level of close-up detail. If you would like to build your own tube, it is available on Thingiverse.
Macro extensions seem far between here, but we’ve brought you a few lens repairs in our time.
The photographic hire company Lensrentals had a $2k Sony FE 135mm f1.8 GM camera lens returned with a problem: it was having issues focusing. So, they decided to do the obvious thing and take it apart. It’s a fascinating insight into some of the engineering that goes into a high-end camera lens.
That is perhaps a rather scary thing to do, because this is a very new lens that doesn’t even have a service manual yet. That’s akin to rechipping a Ferrari when you’ve never even opened the hood before.
One of the interesting things inside is the presence of a number of shims that adjust the placement between the groups of lens elements. It seems that however good their manufacturing tolerances are, sometimes you just have to put a shim or two in there to align things.
Continue reading “Expensive Sony Lens Repair Reveals Shims & Shifts”
Old military equipment can sometimes be found in places like flea markets and eBay for pennies, often because people don’t always know what they have. While [tsbrownie] knew exactly what he was getting when he ordered this mystery device, we’re not sure we could say the same thing if we stumbled upon it ourselves. What looks like a vacuum tube of some sort turns out to be an infrared sensor from an old submarine periscope that was repurposed as a night vision device. (Video, embedded below.)
Of course, getting a tube like this to work requires high voltage. This one specifically needs 3500V in order to work properly, but this was taken care of with a small circuit housed in a PVC-like enclosure. The enclosure houses the tube in the center, with an eye piece at one end and a camera lens at the other, attached presumably by a 3D-printed mount. The electronics are housed in the “grip” and the whole thing looks like a small sightglass with a handle. Once powered up, the device is able to show a classic green night vision scene.
Old analog equipment like this is pretty rare, as are people with the expertise to find these devices and get them working again in some capacity. This is a great video for anyone with an interest in tubes, old military gear, or even if you already built a more modern night vision system a while back.
Thanks to [Zzp100] for the tip!
Continue reading “Hold 3500 Volts Up To Your Eye”
If you’re familiar with the DSLR camera market, you’d know that modern lenses are works of technological art. Crammed full of motors and delicate electronic assemblies, they’re bursting with features such as autofocus, optical stabilization and zoom. [Saulius Lukse] has been experimenting with motorized lenses for webcam applications, and has built a controller to make working with them a snap.
The controller is capable of controlling up to 3 stepper motors, as well as a voice coil, which should be enough for the vast majority of lenses out there. Microstepping is supported, which is key for optical systems in which tiny adjustments can make a big difference. The controller speaks USB and I2C, and is now based on an STM32 chip, having been upgraded from an earlier version which used the venerable ATmega328. The board is designed to be as compact as possible, to enable it to neatly fit inside camera and lens assemblies.
The board has been used to successfully control an 18x zoom lens, among others. Combining such a lens with a webcam and a good pan and tilt mechanism would create a highly capable surveillance package, or an excellent vision system for a robot.
It’s not the first time we’ve seen work from [Kurokesu] in these parts – they’ve done work on pedestrian detection before, too.
There’s a piece of tech that many of us own, but very few of us have dissected. This is strange, given our community’s propensity for wielding the screwdriver, but how many of you have taken apart a camera lens. Even though many of us have a decent camera, almost none of us will have taken a lens to pieces because let’s face it, camera lenses are expensive!
[Anthony Kouttron] has taken that particular plunge though, because in cleaning his Olympus lens he tore its internal ribbon cable from the camera connector to the PCB. Modern lenses are not merely optics in a metal tube, their autofocus systems are masterpieces of miniaturised electronics that penetrate the entire assembly.
In normal circumstances this would turn the lens from a valued photographic accessory into so much junk, but his solution was to take the bold path of re-creating the torn cable in KiCad and have it made as a flexible PCB, and to carefully solder it back on to both connector and autofocus PCB. We applaud both the quality of his work, and thank him for the unusual glimpse into a modern lens system.
Lens repairs may be thin on the ground here, but we’ve had another in 2015 with this Nikon aperture fix.
There are a lot of CNC machines sitting around in basements and garages, but we haven’t seen anything like this. It’s making lenses using a standard CNC machine and a lot of elbow grease.
The process of making a lens with a CNC machine begins by surfacing a waste board and taping an 8mm sheet of cast acrylic down with double-stick tape. The lens is then cut out with an 8mm endmill, removed from the stock material, and wet sanded to remove the tool marks. Wet sanding begins at 400 grit and progresses to 2000 grit, after which the lens is polished with a polishing compound meant for high-gloss car finishes. This was done by hand, but in this instance there’s no shame in using a real buffing wheel.
Several other lenses are demonstrated, including a cylindrical convex lens, but these are only planoconvex lenses, or lenses that are flat on one side. Biconvex lenses can be constructed by gluing two planoconvex lenses back to back, which is done with an acrylic glue, in this case Acrifix adhesive. The result is remarkable: with a lot — and we mean a lot — of sanding and polishing, you can make an acrylic lens on a cheap hobby CNC machine. The trick is just a very small stepover on your CNC path.
There are a few more videos planned in this series, including one on using Fusion 360 on defining the shape of the lens to have the right focal length. We can’t wait to see that.
Continue reading “Creating Lenses On Cheap CNC Machines”