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.
Continue reading “Molding Complex Optics In A Completely Fluid System”
[Florian] is hyped for Google Cardboard, Oculus Rifts, and other head mounted displays, and with that comes an interest in lenses. [Floian] wanted to know if it was possible to create these lenses with a 3D printer. Why would anyone want to do this when these lenses can be had from dozens of online retailers for a few dollars? The phrase, ‘because I can’ comes to mind.
The starting point for the lens was a CAD model, a 3D printer, and silicone mold material. Clear casting resin fills the mold, cures, and turns into a translucent lens-shaped blob. This is the process of creating all lenses, and by finely sanding, polishing, and buffing this lens with grits ranging from 200 to 7000, this bit of resin slowly takes on an optically clear shine.
Do these lenses work? Yes, and [Florian] managed to build a head mounted display that can hold an iPhone up to his face for viewing 3D images and movies. The next goal is printing prescription glasses, and [Florian] seems very close to achieving that dream.
The last time we saw home lens making was more than a year ago. Is anyone else dabbling in this dark art? Let us know in the comments below and send in a tip if you have a favorite lens hack in mind.
Now this is some seriously cool stuff. The folks over at FormLabs decided to try a little experiment to test the optical clarity of their clear resin. It’s pretty damn clear.
Using their own slicing software, PreForm, [Craig Broady] printed the lens piece in an orientation that would maximize resin flow around the lens to help prevent defects, keeping it as smooth as possible. While the printed part looks quite clear, all lenses require some form of polishing to become optically clear. It was printed with a 50 micron resolution, and [Craig] used a power drill to sand the lens down from 220 grit to 2000 grit sand paper.
Continue reading “3D Printed Lenses Open Up Possibilities”