Inexpensive Reading Glasses Become Stereoscope

It’s an unfortunate consequence of growing older, that no longer are you able to read the print on a SOT-23 package or solder a QFN without magnification. Your eyes inexorably start to fail, and to have any hope of continuing a set of reading glasses is required. We have this in common with [Niklas Roy], who noticed while shopping for cheap reading glasses that their lenses were of surprisingly good quality. The result of this observation was a stereoscope made from card and a few euros worth of eyewear.

In the tradition of [Niklas]’ work it has a high level of attention to detail, which manifests itself here in a parametric web-based template generator to produce a result tailored to your glasses. It’s a fairly straightforward trapezoid shape, with a compound lens made from two sets of glasses drilled and held back-to-back with zip ties.

It served as a project for a group of children, and of course because stereo cameras are a relative rarity he also investigated taking his own pictures by moving a smartphone for left and right eye perspectives. It seems the youngsters had a lot of fun.

These lenses hadn’t come up on our radar until now, but like many goodies in a dollar store they’re certainly something to take a look at. Maybe not as a stereoscope for everyone though, some of us can’t see what the fuss is about.

Lenses: From Fire Starters To Smart Phones And VR

In antiquity, we see examples of magnifying crystals formed into a biconvex shape as early as the 7th century BC. Whether the people of that period used them either for fire-starting purposes or vision is unclear. Still, it is famously said that Emperor Nero of Rome watched gladiator games through an emerald.

Needless to say, the views we get through modern lenses are a lot more realistic. So how did we get from simple magnifying systems to the complex lens systems we see today? We start with a quick journey through the history of the camera and the lens, and we’ll end up with the cutting edge in lens design for smartphone cameras and VR headsets.

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Molding complex lenses

Molding Complex Optics In A Completely Fluid System

Traditional lensmaking is a grind — literally. One starts with a piece of glass, rubs it against an abrasive surface to wear away the excess bits, and eventually gets it to just the right shape and size for the job. Whether done by machine or by hand, it’s a time-consuming process, and it sure seems like there’s got to be a better way.

Thanks to [Moran Bercovici] at Technion: Israel Institute of Technology, there is. He leads a team that uses fluids to create complex optics quickly and cheaply, and the process looks remarkably simple. It’s something akin to the injection-molded lenses that are common in mass-produced optical equipment, but with a twist — there’s no mold per se. Instead, a UV-curable resin is injected into a 3D printed constraining ring that’s sitting inside a tank of fluid. The resin takes a shape determined by the geometry of the constraining ring and gravitational forces, hydrostatic forces, and surface tension forces acting on the resin. Once the resin archives the right shape, a blast of UV light cures it. Presto, instant lenses!

The interface between the resin and the restraining fluid makes for incredibly smooth lenses; they quote surface roughness in the range of one nanometer. The use of the fluid bed to constrain the lens also means that this method can be scaled up to lenses 200-mm in diameter or more. The paper is not entirely clear on what fluids are being used, but when we pinged our friend [Zachary Tong] about this, he said he’s heard that the resin is an optical-grade UV adhesive, while the restraining fluid is a mix of glycerol and water.

We’re keen to see [Zach] give this a try — after all, he did something similar lately, albeit on a much smaller scale.

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From An Eye To An Eye: Human Muscles As A Joystick

The interface between humans and machines has been a constantly evolving field. Sure the computer mouse was a game-changer, but time moves on. We are now looking at integrating machines via soft HMIs for personal applications. A research team led by the University of California, San Diego has presented a paper interfacing a soft lens with the human eye.

The lens itself is a pair of electroactive elastomer films that encapsulates a small quantity of saltwater. These films constitute the muscle and are controlled by an external source of electrical pulses. The signals are generated when electrodes placed around the eye of a subject and detect movement. Actions such as blinking are converted to a zoom-in-zoom-out activity which is designed to mimic human squinting.

The suggested potential applications are visual prostheses, adjustable glasses, VR, and even soft robots eyes. Yes, we are heading from whirring robots to squishy robots, but that also means that people with disabilities can get a second chance. This approach is non-invasive as opposed to brain implants.


[Thanks for the tip Qes]

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Lenses For DIY Augmented Reality Will Get A Bit Less Unobtainable

You may remember that earlier this year Leap Motion revealed Project North Star, a kind of open-source reference design for an Augmented Reality (AR) headset. While it’s not destined to make high scores in the fashion department, it aims to be hacker-friendly and boasts a large field of view. There’s also an attractive element of “what you see is what you get” when it comes to the displays and optical design, which is a good thing for hackability. Instead of everything residing in a black box, the system uses two forward-facing displays (one for each eye) whose images are bounced off curved reflective lenses. These are essentially semitransparent mirrors which focus the images properly while also allowing the wearer to see both the displays and the outside world at the same time. This co-existence of both virtual and real-world visuals are a hallmark of Augmented Reality.

A serious setback to the aspiring AR hacker has been the fact that while the design is open, the lenses absolutely are not off the shelf components. [Smart Prototyping] aims to change that, and recently announced in a blog post that they will be offering Project North Star-compatible reflective lenses. They’re in the final stages of approving manufacture, and listed pre-orders for the lenses in their store along with downloadable 3D models for frames.

When Leap Motion first announced their open-source AR headset, we examined the intruiguing specifications and the design has since been published to GitHub.  At the time, we did note that the only option for the special lenses seemed to be to CNC them and then spring for a custom reflective coating.

If the lenses become affordable and mass-produced, that would make the design much more accessible. In addition, anyone wanting to do their own experiments with near-eye displays or HUDs would be able to use the frame and lenses as a basis for their own work, and that’s wonderful.

Low Cost Optics Bench Project – Now With Lasercut Optics

[PWalsh] has a clever idea for learning and experimenting with basic optics: instead of using actual lenses, he’s using clear pieces of laser-cut acrylic cut into lens profiles instead. They are much easier to make, mount, adjust, and handle while still bending light in the same basic ways. It allows for simple hands-on experimentation with plenty of visual feedback – perfect for beginners.

Optical Group

This idea is part of [PWalsh]’s low-cost optics bench project, which uses laser-cut plastic to create adjustable optics bench components. We’ve covered this project before, but [PWalsh] expanded the idea with the concept of these simple laser-cut optics for basic experimentation; an addition that requires no additional tools and only a small amount of material. Features and value added for nearly zero cost is something we always love to see!

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Hackaday Prize Entry: Optical Experiments Using Low Cost Lasercut Parts

Experimenting with optics can be great fun and educational. Trouble is, a lot of optical components are expensive. And other support paraphernalia such as optical benches, breadboards, and rails add to the cost. [Peter Walsh] and his team are working on designing a range of low-cost, easy to build, laser cut optics bench components. These are designed to be built using commonly available materials and tools and can be used as low-cost teaching tools for high-schools, home experimenters and hacker spaces.

They have designed several types of holders for mounting parts such as lasers, lenses, slits, glass slides, cuvettes and mirrors. The holder parts are cut from ¼ inch acrylic and designed to snap fit together, making assembly easy. The holders consist of two parts. One is a circular disk with three embedded neodymium magnets, which holds the optical part. The other is the base which has three adjustment screws which let you align the optical part. The magnets allow the circular disk to snap on to the screws on the base.

A scope for improvement here would be to use ball plunger screws instead of the regular ones. The point contact between the spherical ball at the end of the screw and the magnet can offer improved alignment. A heavy, solid table with a ferrous surface such as a thick sheet of steel can be used as a bench / breadboard. Laser cut alignment rods, with embedded magnets let you set up the various parts for your experiment. There’s a Wiki where they will be documenting the various experiments that can be performed with this set. And the source files for building the parts are available from the GitHub repository.

Check out the two videos below to see how the system works.

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