8 ms·
Graphene optical lens 200 nm thick breaks the diffraction limit
- huxley 11y agoI find the "billionth of a metre thick" phrasing painful, but I guess it's better than if they'd written that it was "a trillionth of a kilometre thick"
- cjfont 11y agoThey can't be flaunting around big words like nanometer, it might discourage a layperson from reading the article.
- huxley 11y agoDecent point, but most people familiar with metric would work with smaller units than metres and for those unfamiliar with metric, describing it as a billionth of a yard would still sound like a pretty peculiar. I think describing it as a minute fraction of an inch or centimetre would still be pretty accessible without having to get people to visualize a nanometre.
- deleted 11y ago[deleted]
- sageikosa 11y agoRight, I thought the usual layperson speak was to compare it to the thickness of human hair or a spider web.
- Florin_Andrei 11y agoBTW, it's not even 1 billionth of a metre thick. It's 200 nm. That's 0.2 microns. That's 2 * 10^-7. It's 0.2 of a millionth. They should have just said 0.2 microns instead. It carries just as much actual meaning for the layperson, and it's a lot easier to parse if you are scientifically literate.
- nitid_name 11y agoI thought convention in SI units was to drop down a level when at less than 1 of a unit..?
- lytfyre 11y agoA pretty common approach (at least in Canada) is to use prefixes at intervals of 1000 - mm, m, km and then larger unit to one decimal for large values - 700m as 0.7km, 0.9l instead on 900ml, and so-on. you'll rarely see cl, dg, or hm used here.
- AnimalMuppet 11y agoUm, 1 billionth of a meter is 1 nm. Saying it's 200 nm (like the paper says) is very different from saying it's 1 billionth of a meter (like the linked article incorrectly says).
- NamTaf 11y agoThough it's almost unheard of now, a british billion = 1000 * a british million. In that context it does hold, being 2 british billionths of a metre thick. That said, here we all bascially use the American 'billion' because it makes a more logical approach and allows for dealing with larger numbers more easily.
- beobab 11y agoI thought it used to be: a british billion is a million million i.e. 1,000,000,000,000. Thus a british billion is 1000 * an american billion. Nowadays we use the american billion of 1,000,000,000. Pretty sure we all agree that a million is a thousand thousand.
- dang 11y agoOK, we've replaced that with "200 nm". Let's stay on topic now.
- biomcgary 11y agoA molecular scale Fresnel lens! Now we can create retro style nano-projectors, even if the transparency will be thicker than the lens.
- tgb 11y agoIs it really a Fresnel lens? I was thinking it was more of a diffraction grating. The paper describes it as > The 3D focusing is a result of the interferences of wavelets originated in the lens plane from different zones19, as illustrated in Fig. 1d. Which suggests it's more about interference than about Snell's law.
- graycat 11y agoThat was my guess, too.
- frozenport 11y agoThings with rings are generally called Fresnel lenses, even if its not about interference, see: https://en.wikipedia.org/wiki/Zone_plate https://en.wikipedia.org/wiki/Zone_plate
- dTal 11y agoFresnel zone plate, yes. Fresnel lens, no; they are not lenses. This does look like a microscopic zone plate. This is not a new idea though, it's how we focus X-rays as most materials don't refract X-rays very well; I guess they just managed to make a really small one. I wonder in what sense it "breaks the diffraction limit".
- crispyambulance 11y agoIt does not "break" the diffraction limit. The title is inaccurate. The actual paper doesn't say they've broken the diffraction limit. They only achieve a subwavelength focal point. I'll make an attempt to mansplain this... The actual diffraction limit depends on wavelength (lamda) and the numerical aperture (NA) of the lens. Diffraction limit is ~ lamda/(2*NA). In traditional objective lenses used in confocal scanning microscopes, the diffraction limit has been ~0.5 microns. If you increase NA, it also means decreasing working distance-- to the point where the focal point meets the surface of the lens. They've managed to increase NA with their zone plate, but since their "lens" thickness is "200 nm", they still have a useable working distance.
- ChuckMcM 11y agoLink to the paper: http://www.nature.com/ncomms/2015/150922/ncomms9433/pdf/ncomms9433.pdf http://www.nature.com/ncomms/2015/150922/ncomms9433/pdf/ncom... This is an excellent result. It could also provide an interest boost to solar in terms of $/watt by focusing more light into a small area. Fun times.
- dookahku 11y agoDoes that 'wear-out' the panel quicker? I assume that more light focused can mean more heat. I'm told people try something similar with mirrors now but it tends to not work out well for the panel itself.
- dogma1138 11y agoMirros are only used for thermal solar applications where one heats up oil or melts salts to produce steam to power a normal power turbine. https://en.wikipedia.org/wiki/Solar_thermal_energy https://en.wikipedia.org/wiki/Solar_thermal_energy For photovoltaics you do not want to focus the light for many reasons the cell has a cap per surface area that it can produce, you don't want voltage spikes across the subcells (if it exceeds the overall limits of the cell it will damage it), it wears out the cell, and the cell efficiency drops as the temperature increases.
- mikeash 11y agoMirrors and lenses can be used with photovoltaics as well: https://en.wikipedia.org/wiki/Concentrator_photovoltaics https://en.wikipedia.org/wiki/Concentrator_photovoltaics I know pretty much nothing about it besides the fact that it exists, though.
- kyzyl 11y agoThe power coming from the sun is approximately constant. The power hitting any given spot on the planet is far from constant due to weather, day/night cycles and seasonal shifts. For a given solar installation, there might be a time where the ambient intensity (power per unit area) of the light has the cells biased just-so, converting energy at a near ideal efficiency. Of course then the conditions change and this isn't the case any more. When you run into that scenario, i.e. the sun has moved a bit, it becomes very useful to have some kind of mirror or lens to increase the intensity by collecting more of the light and concentrating it to a smaller area, thus bringing you closer to your ideal operating point. You're correct that at some point you get undesirable transients, or you just melt your cell. I do that by accident more often than I'd like, by shining infrared lasers at a photo diodes while forgetting that I've left a microscope objective in front. Expensive mistakes. Now re: the article, if you ask me the really interesting thing here isn't being able to focus light to really small areas per se, but that they've broken the diffraction limit. This means you can form an image of an object that is smaller than a half-wavelength of light. For e.g. red light, that means you can take a picture, an optical picture, of something like, say, a mosfet on a chip. Or a virus. That's quite something. I'll note however that I could foresee (read: speculate) a scenario where having such a tiny focus, like the solar cell scenario, could invoke a quantum mechanical effect in some special material whereby the light coupling becomes much greater, thus increasing efficiency or something. But that's just science fiction as far as I know. PS: Sorry if this is patronizing. I know nothing about my audience ;-)
- Eridrus 11y agoWould this also allow visible light microscopes to zoom in further than they currently can?
- gavman 11y agoMy apartment mate (currently a PhD student in Chemistry) noted that the research is cool, but article this is based on in Nature Communications is pay to publish, so err on the side of skepticism. A quick Google search found this: http://www.the-scientist.com/?articles.view/articleNo/41072/title/Nature-Communications-Goes-OA/ http://www.the-scientist.com/?articles.view/articleNo/41072/... "At present, researchers can choose an open-access option when submitting a manuscript to the journal, selecting one of three publishing licenses: Creative Commons Attribution 3.0 Unported (CC BY), the more restrictive Creative Commons Attribution-NonCommercial-No Derivs 3.0 Unported (CC BY-NC-ND), or Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA). Authors pay a fee of $5,200 to publish a study under a CC BY license, and $4,800 for each of the other two... Update (September 23): After this article was published, Nature Publishing Group's Amy Bourke responded to The Scientist, noting the flat article processing charge (APC) to publish in Nature Communications: $5,200" Edit: other users seem to note that the journal is very reputable. I do not know myself, was reporting my apartment mate's reaction since he is much more knowledgeable in the area. It is clear from conversation I mis-understood his response. Apologies.
- spoonsso 11y agoMost reputable journals charge processing fees when publishing.
- dhj 11y agoAnd just about all of them have higher fees if you want it published under a creative commons (open) license. Note in GP's quote: the researcher can choose CC for a fee. This option has come available in nearly all peer review journals recently due to recent US grant requirements to open published results. They still have to go through a rigorous peer review. Frankly, GP's mate doesn't know what he's talking about.
- gavman 11y agoIt's clear at this point I must have mis-understood his response. He's at a top tier school (CMU) so my guess is he knows what he's talking about. Apologies.
- sandworm101 11y agoWhat is the operating temperature of such lenses? Is this one of those magic devices that only exists near absolute zero? I assume these can be built into sheets to focus light onto masks. No doubt intel might be interested.
- bcraven 11y ago"Just over two years ago, PhD student at Swinburne’s Centre for Micro-Photonics, Xiaorui Zheng, tried fashioning a lens using graphene oxide — a variation of the super-strong, atom-thick carbon material, graphene. The team, led by Associate Professor Baohua Jia, developed a three-dimensional printer that could quickly and cheaply produce the lens using a sprayable graphene oxide solution. Lasers were used to precisely pattern the surface, creating three concentric rings of reduced graphene oxide, which enabled its extraordinary focus" No I think it's purely geometrical.
- JumpCrisscross 11y agoIt seems like every month brings a new "miracle" application for graphene. Are these breakthroughs as surprising for the experts as they are for the layperson? If not, what fundamental properties would allow one to extrapolate its applications?
- zwu 11y agoimaging if the lens being used for the light field display, could be another solution for a mixed reality display device that the Magic Leap is developing.
- soylentcola 11y agoEven more "traditional" VR/AR devices would benefit from techniques to make thinner lenses. Advances in optical engineering will have as big a part to play in that sort of thing as processing power and faster chips.
- theandrewbailey 11y ago> It’s early days, but the new technology has the potential to reduce the size and weight of mobile phones in which cameras are currently dependent on thick and heavy lenses. Maybe by comparison to this, but hardly anyone cares about the size or weight of their phone camera lens.
- hanief 11y agoCounter example: the protruding camera bump on iPhone 6/6S.
- Cthulhu_ 11y agoI like to think that's more due to the total thickness of the camera unit, not so much the lens. That, or the required distance between the lens and sensor. Either way, it's a bad design decision, one they're embarrassed of themselves (it's edited out on sideways images of the device on apple's website)