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Metamaterial based flat lens promises possible revolution in optics
- tener 10y agoLooks exciting on paper, but I wonder how much work is needed to bring this to mass production.
- brudgers 10y agoI suspect that demand is more likely to drive production scale than technology, but I am drawing an analogy with the economics of microprocessors and their fabrication.
- infogulch 10y agoIt looks like they had that in mind while they were designing it: "But our lenses, being planar, can be fabricated in the same foundries that make computer chips. So all of a sudden the factories that make integrated circuits can make our lenses." If this is true, I imagine old foundries could produce these since they probably don't need anything near the precision or consistency that current-gen chips require.
- wlesieutre 10y agoMy understanding of these flat metamaterial lenses is that they're fine-tuned for a single wavelength of light; you can't put one in a camera and expect it to work like a glass lens did. I'm sure there are applications where control of monochromatic light is important, but I couldn't tell you what they are. It's an awfully important detail to completely omit from an article.
- alcubierredrive 10y agoFor smartphones, where thinness is very important but area is less so, it would not be unprecedented to make an array of 4 monochromatic cameras and rectify and combine the images computationally. R G G B
- Strilanc 10y agoThat would treat monochromatic yellow light differently from yellow light made up of a combination of red and green, instead of treating them the same like the human eye does. The yellow of an actual banana would distort differently from the yellow coming from a picture of banana displayed on an LCD.
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- wlesieutre 10y agoEureka! We can make high precision, flat optics for Low Pressure Sodium lights! http://www.atmo.arizona.edu/students/courselinks/spring08/atmo336s1/courses/spring11/nats101s13/lecture_notes/em_radiation/Na_vapor_spectrum.png http://www.atmo.arizona.edu/students/courselinks/spring08/at...
- BurningFrog 10y agoUnfortunately, that is not how light and perception works. There are thousands/millions¹ of separate visible light frequencies. Our eyes and brains takes that all in and does an enormously lossy mapping of that to 3 perceived colors. If you only record 3 of those thousands/millions of frequencies, you will lose 99.9% of the light, and mostly make black photos. ¹ depending on how wide the frequency interval considered monochromatic is.
- Finnucane 10y agoIt _is_ possible to do trichromatic color photography with sets of single-color filters. In fact, the earliest color photography was done this way. Technicolor films were shot in a camera that recorded three monochromatic strips simultaneously. (it is true that the filters were generally not strictly a single color frequency, but a narrow band)
- alexbock 10y agoThe difference is that they were using film which was sensitive over the entire visible spectrum with color filters that allowed a broad range of wavelengths that are all perceived as the same color. If you had a smartphone camera filtered with a 1 nm bandpass filter for a particular wavelength, you're going to get so little light that it will be like taking pictures in the dark. The filter approach is still used in most cameras (Bayer filters) but a vary narrow wavelength bandpass would not be appropriate for a consumer camera.
- stcredzero 10y agoI'm sure there are applications where control of monochromatic light is important, but I couldn't tell you what they are. What about VR headsets? Flat lenses are good in that case, and you'd just have to manipulate 3 wavelengths.
- wlesieutre 10y agoStill more than 3 wavelengths, even with OLED screens. Check out the gray line here: http://www.displaymate.com/Spectra_4.html http://www.displaymate.com/Spectra_4.html Maybe close enough that it would work, but I'm also not sure whether you can do these metamaterial lenses for three wavelengths at once. If it's even possible, AFAIK it's not a solved problem.
- anon1253 10y agoYep. Still useful for things like fluorescence microscopy or astrophotography though. There you're usually interested in just the specific wave length, like the (Green) Fluorescent Protein emissions for microscopes, or the Hydrogen Alpha emissions in astrophotography. Rather than working with filter sliders, you'd essentially need to use a different lens for each wave length though …
- outsidetheparty 10y agoAccording to the abstract (http://science.sciencemag.org/content/352/6290/1190 http://science.sciencemag.org/content/352/6290/1190), >Diffraction-limited focusing is demonstrated at wavelengths of 405, 532, and 660 nm with corresponding efficiencies of 86, 73, and 66%. ...but I'm not clear on whether that is from a single lens or if they constructed different lenses for each color. (Those wavelengths correspond to violet, green, and red light fwiw) EDIT: the full paper makes it clear this is three separate lenses, so yeah, you're right.
- ant6n 10y agoscreens separate out different colors into different areas at a small scale, wouldn't this work here as well?
- guelo 10y agoWhy couldn't multiple patterns sensitive to different frequencies be printed on the same surface?
- Natanael_L 10y agoUnless you can couple them with very tiny prisms, space + getting enough light is the problem.
- azernik 10y agoThe most obvious application of single-frequency lenses is in fiber optic communication transceivers (a single-frequency laser, or a series of such lasers in Wavelength Division Multiplexing). From my understanding these are a big source of component cost and failure rates. See e.g. http://www.panduit.com/heiler/InstallInstructions/PN541.pdf http://www.panduit.com/heiler/InstallInstructions/PN541.pdf
- JulianMorrison 10y agoHow about lasers? How about flat lasers, on chips, using laser diodes and flat lenses? Or camera pixels on the nano scale?
- BurningFrog 10y agoI can imagine a monochromatic microscope, where you can see the shape of tiny things, and you do not care about colors.
- ambicapter 10y agoChromatic aberration is already a thing. Are you saying that these lenses only work for a certain wavelength and their performance drop offs significantly when you go even slightly off-wavelength?
- Aelinsaar 10y agoI'm not sure if this is where and when metamaterials break into the mass market, but it's bound to happen sometime in the next 5-10 years, why not now?
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- justinclift 10y agoGah. Maybe we should add a "[flash]" warning for links that seems to want Adobe Flash installed for important parts of the content. :(
- dkbrk 10y agoFull article: http://science.sciencemag.org.sci-hub.cc/content/352/6290/1190 http://science.sciencemag.org.sci-hub.cc/content/352/6290/11... These lenses are designed for a specific wavelength, and if I am reading the paper properly, only work with circularly polarised light. Essentially, for a given design wavelength and focal length there is a desired phase shift at each point on the lens. This phase shift is caused by the titanium dioxide "nanofins" which rotate the circularly polarised light to produce the desired phase shift. The phase shift is determined by the angle at which each fin is rotated. This produces a pattern of fins rotated relative to one another, which can be seen in the images of the BBC article. While the lenses are designed for a target wavelength, they're not entirely useless at other wavelengths, they just have terrible chromatic aberration. In all other respects they seem to be excellent (especially for their size), but this makes them useless for most commercial applications. To manufacture the lenses, they start with a substrate of silicon dioxide; not actually glass as said in the article, but quartz, like sand. This is coated by a resist, which is patterned by electron-beam lithography. The resist is "positive", meaning that the exposed part is removed when developed. A thin layer of titanium dioxide is deposited using atomic layer deposition. This is a type of thin film deposition technique that allows the deposition of a single atomic layer at a time. This is accomplished by introducing two different precursors one at a time alternately in sequence, the number of cycles determines the number of layers. With this they can essentially deposit just enough TiO2 to fill the holes left in the resist, though it also deposited on top of the unexposed resist. The TiO2 remaining on top of the undeveloped resist is etched off and the undeveloped resist is removed, leaving just the nanofins. The nanofins have a high "aspect ratio", meaning height-to-width, which makes them challenging to produce using most semiconductor fabrication techniques. They are however quite large compared to modern semiconductors, on the order of hundreds of nanometers, which makes most things easier. Semiconductor fabrication uses photolithography, this used electron-beam lithography. While electron-beam lithography can in principle produce smaller feature sizes than photolithography (due to the smaller wavelength of electrons), that was not needed for this application; rather electron-beam lithography does not require the creation of a photomask and is consequently much more useful for small scale prototyping. Commercially producing these lenses at scale could potentially be done with photolithography, though there would be a large upfront cost due to the need to fabricate photomasks. Monocrystalline silicon substrates are standard and silicon-dioxide-on-silicon is extremely common; I suspect the lenses could be fabricated on such a SiO2-Si substrate and the silicon on the back face removed, leaving optically transparent lenses.
- iamleppert 10y agoHow is this different than what can be achieved using holographic optical elements, which can routinely make optical lenses and materials using the principle of holography and can be diffraction limited, producing feature sizes that are 1/n the wavelength of light (depending on the mastering process)?
- gradi3nt 10y agoYou have to love pop sci headlines with phrases like "...promises possible..." I promise you, BBC's Roland Pease, that it's possible the sun won't rise tomorrow and Linus Torvalds with announce that he will be Microsoft's next CEO.
- jwatte 10y ago"Shapes on the surface of this lens are smaller than the wavelength of light involved: a thousandth of a millimetre." A micron is 1000 nm and visible light is about 900 nm and down. Close but no cigar.
- swframe 10y agoCan it see proteins, cell walls or viruses?
- erikj 10y agoI wonder if it can be used to improve VR optics and make HMDs cheaper.
- bobsil1 10y agoBetter for transparent AR lenses than the current holographic and waveguide approaches.
- styrophone 10y agoIs this much different from Diffractive Optical Elements in use today?