There's been a practical solution to this problem for years - standard round lenses. Spectacles have three parameters - spherical radius, cylindrical radius, and axis. For round lenses, axis is set by mounting in the frame. There's a notching tool which notches the lens so it's retained in the frame at a fixed angle. So you only need a set of a few hundred standard plastic lenses, which fits in a small suitcase.
This was developed in India decades ago, but I can't find those kits online. Obsolete?
I got so frustrated with eye glasses that never had the correct prescription that I purchased an optometrist kit off Amazon for $200
I had spent over 10,000 at various eye doctors.
Helped me figure out what was going on. ( unstable prescription)
This is enough for the basics, but modern lenses are more complex. Eg multifocals for basically anyone over 45, or high end custom lenses that can correct higher order aberrations.
Anyway, the optometrist lenses kits are still there, you can order them from aliexpress.
Basically it is possible to make much more affordable glasses but people like Luxxotica keep it from happening because it cuts into their margins.
That said, making complex lenses this way would make building things like microscope pretty straightforward. There is a lot of optical equipment that needs lenses that this technique could satisfy.
The article doesn't explain how they've been able to keep the "affordable glass" competition out of the market though. Natural monopolies are quite rare. My intuition is that this is not a free market and there is some degree of regulatory capture. I'm guessing not just anyone can set up shop and start manufacturing/selling cheap prescription glasses? Can you import them easily?
> These glasses contain lenses which can be self-adjusted by the wearer to their prescription, and were developed as a low-cost and accessible eye care solution for people in developing nations. The lens consists of two membranes, in between which silicon oil can be pumped with the syringes on the side of the frames. As fluid is pumped in or out, the focal length of the lens is changed, meaning the lens can be tuned to the specific requirements of the eye. The syringes can then be removed. The inventor of these glasses was nominated for a 2011 European Invention Award.
Affordable freeform optics is especially exciting:
> These optical components are neither convex nor concave, but instead are shaped as topographic surfaces, with light hitting the surface in different areas to achieve the desired result. Such parts can be found in multi-focal glasses, pilot helmets, advanced projector systems, virtual and augmented reality systems, and elsewhere.
In this work, we demonstrate curing of PDMS (Sylgard 184, Dow, MI), and UV adhesive (NOA61, NOA63, NOA81, Norland, NJ) lenses. The PDMS lenses are cured by incubating them at 80 C for 1.5 hr, at 60 C for 4 hr, or at room temperature for 24 hr. The UV adhesive is cured by exposure to light at 365 nm (a 36 W consumer grade nail lamp) for 2-5 min, depending on the thickness of the lens and the specific adhesive chosen. Since both PDMS and Norland adhesives are immiscible in water and have densities between ~1.03 (PDMS) g/mL and ~1.12 g/mL (Norland), the water\glycerol-based immersion liquid allowed us to precisely control the density difference. Since preparation of PDMS involves intense mixing of the base resin with a cross-linker, we degassed the PDMS mixture for 20 minutes before injecting it into the bounding surface, in order to eliminate any bubbles trapped in the fluid due to the mixing.
Wasn't there, like a decade ago, some university researcher (MIT?) who came up with the idea for a portable lens forming machine that could make arbitrary lens shapes on demand in the field? Maybe it involved rapid curing plastic or something, and a mold that could be shaped easily.
I remember it being described as great for rural areas where it was unlikely / difficult to ensure you would be able to make a return visit or get the people needing glasses to come back when the lenses were eventually ready.
A good portion of my eyeglasses (custom prescription, with astigmatism correction) have been <$10 drop shipped to the US from Hong Kong, frames and lenses included.
The most expensive variations (Transition sunglasses, complicated plastics to be thinner, memory metal frames) were $70, frames and lenses included. Most pairs end up in the $20-$40 range shipped.
All this $150-$600 nonsense in the US just pays for the retail space, the branding, the insurance bureaucracy, and rent-seeking by the Luxxotica cartel.
The downside is that I don't get to try them on beforehand... but nothing so far has been totally unwearable, and buying six pairs for $200, as I did once, addresses that concern pretty well.
You can buy glasses from online sites owned by the world's largest lens manufacturer who sells the identical lenses to B&M stores. Requires some work to find the right fit between frame and face, but this can be learned. Online price includes one free lens remake, if adjustments are needed.
Lenses are already quite cheap to make. You can get prescription glasses fitted to a knockoff designer frame of your choice in half an hour for less than $50 in e.g. Shanghais knock off malls. You don't even have to bring your prescription, they use a laser device to measure the glasses you brought with you.
Even in Finland you can get basic standard prescription glasses for 59€, or even second sunglass pair for same price(not polarizing though). And the measurements are free too...
Though these are standard material lenses and price really goes up when you want thinner and lighter for higher refraction.
Still, just how cheap something standardised can be even in country with high labor cost is amazing.
I’ve done this in Beijing. I asked for sunglasses and they gave me the lenses and the frame separately, then at the back of the building, some person dipped the lenses in a dark liquid and after drying, put them in the frame for me. Amazing.
Can someone explain me how this works? The article mentions a "rigid frame". Does that frame need to have the (inverse) shape of the lense? Is the method thus just a way to copy lenses or can it make a truly new (i.e. more precise than all necessary tools) one?
"sweat equity" is as cheap as you are willing to work
... after reading the article, spherical lenses are great in many many applications, there is still a place for aspheric optics one of which is large aperture telescopes you can reach without an orchard ladder or drone.
the sibling comment on spinning fluids does lead the question; can the researchers vary the density of their neutral fluid (or polymer) to gradually vary the "local" forces shaping the lens
It’s a combination of surface tension and buoyancy; the resulting minimum energy surface can be designed to whatever freeform shape you want by controlling the liquid density and the geometry of the frame.
[+] [-] Animats|3 years ago|reply
This was developed in India decades ago, but I can't find those kits online. Obsolete?
[+] [-] treeman79|3 years ago|reply
Helped me figure out what was going on. ( unstable prescription)
[+] [-] jtwaleson|3 years ago|reply
Anyway, the optometrist lenses kits are still there, you can order them from aliexpress.
[+] [-] baybal2|3 years ago|reply
[deleted]
[+] [-] ChuckMcM|3 years ago|reply
Basically it is possible to make much more affordable glasses but people like Luxxotica keep it from happening because it cuts into their margins.
That said, making complex lenses this way would make building things like microscope pretty straightforward. There is a lot of optical equipment that needs lenses that this technique could satisfy.
[+] [-] olalonde|3 years ago|reply
[+] [-] walterbell|3 years ago|reply
> These glasses contain lenses which can be self-adjusted by the wearer to their prescription, and were developed as a low-cost and accessible eye care solution for people in developing nations. The lens consists of two membranes, in between which silicon oil can be pumped with the syringes on the side of the frames. As fluid is pumped in or out, the focal length of the lens is changed, meaning the lens can be tuned to the specific requirements of the eye. The syringes can then be removed. The inventor of these glasses was nominated for a 2011 European Invention Award.
Affordable freeform optics is especially exciting:
> These optical components are neither convex nor concave, but instead are shaped as topographic surfaces, with light hitting the surface in different areas to achieve the desired result. Such parts can be found in multi-focal glasses, pilot helmets, advanced projector systems, virtual and augmented reality systems, and elsewhere.
[+] [-] kps|3 years ago|reply
If that could be fast enough, then combined with eye tracking we could have full-field glasses for presbyopia.
[+] [-] ridgeguy|3 years ago|reply
[1]https://www.researchgate.net/publication/354978270_Fabricati...
[+] [-] vbezhenar|3 years ago|reply
In this work, we demonstrate curing of PDMS (Sylgard 184, Dow, MI), and UV adhesive (NOA61, NOA63, NOA81, Norland, NJ) lenses. The PDMS lenses are cured by incubating them at 80 C for 1.5 hr, at 60 C for 4 hr, or at room temperature for 24 hr. The UV adhesive is cured by exposure to light at 365 nm (a 36 W consumer grade nail lamp) for 2-5 min, depending on the thickness of the lens and the specific adhesive chosen. Since both PDMS and Norland adhesives are immiscible in water and have densities between ~1.03 (PDMS) g/mL and ~1.12 g/mL (Norland), the water\glycerol-based immersion liquid allowed us to precisely control the density difference. Since preparation of PDMS involves intense mixing of the base resin with a cross-linker, we degassed the PDMS mixture for 20 minutes before injecting it into the bounding surface, in order to eliminate any bubbles trapped in the fluid due to the mixing.
[+] [-] incompatible|3 years ago|reply
[+] [-] onionisafruit|3 years ago|reply
[+] [-] supernova87a|3 years ago|reply
I remember it being described as great for rural areas where it was unlikely / difficult to ensure you would be able to make a return visit or get the people needing glasses to come back when the lenses were eventually ready.
[+] [-] mapt|3 years ago|reply
Describes both a dial-based and a less mature fluid-based technology: https://www.youtube.com/watch?v=D9FpEWQkg-w
Dial-based: https://www.designboom.com/technology/eyejusters-self-adjust...
DialVision review: https://www.youtube.com/watch?v=Ge3H0FtGUw8
[+] [-] thayne|3 years ago|reply
And yet prescription glasses cost two orders of magnitude more than that.
[+] [-] mapt|3 years ago|reply
A good portion of my eyeglasses (custom prescription, with astigmatism correction) have been <$10 drop shipped to the US from Hong Kong, frames and lenses included. The most expensive variations (Transition sunglasses, complicated plastics to be thinner, memory metal frames) were $70, frames and lenses included. Most pairs end up in the $20-$40 range shipped.
All this $150-$600 nonsense in the US just pays for the retail space, the branding, the insurance bureaucracy, and rent-seeking by the Luxxotica cartel.
The downside is that I don't get to try them on beforehand... but nothing so far has been totally unwearable, and buying six pairs for $200, as I did once, addresses that concern pretty well.
[+] [-] walterbell|3 years ago|reply
[+] [-] unknown|3 years ago|reply
[deleted]
[+] [-] 2dvisio|3 years ago|reply
[+] [-] heeen2|3 years ago|reply
[+] [-] Ekaros|3 years ago|reply
Though these are standard material lenses and price really goes up when you want thinner and lighter for higher refraction.
Still, just how cheap something standardised can be even in country with high labor cost is amazing.
[+] [-] bartvk|3 years ago|reply
[+] [-] choeger|3 years ago|reply
[+] [-] mordae|3 years ago|reply
The other side is flat.
[+] [-] civilized|3 years ago|reply
[+] [-] avidiax|3 years ago|reply
https://en.wikipedia.org/wiki/Liquid-mirror_telescope
[+] [-] tejtm|3 years ago|reply
... after reading the article, spherical lenses are great in many many applications, there is still a place for aspheric optics one of which is large aperture telescopes you can reach without an orchard ladder or drone.
the sibling comment on spinning fluids does lead the question; can the researchers vary the density of their neutral fluid (or polymer) to gradually vary the "local" forces shaping the lens
[+] [-] dsr_|3 years ago|reply
[+] [-] hsuduebc2|3 years ago|reply
[+] [-] torginus|3 years ago|reply
[+] [-] peterbmarks|3 years ago|reply
[+] [-] ryandamm|3 years ago|reply
[+] [-] tomrod|3 years ago|reply
[+] [-] mlatu|3 years ago|reply
maybe it is possible to create microstructures using a phase array ultrasound emitter?
[+] [-] charcircuit|3 years ago|reply
[+] [-] mateo1|3 years ago|reply
[+] [-] lesgobrandon|3 years ago|reply
[deleted]