More on Lenses with a Negative Index of Refraction 300
Roland Piquepaille writes "A University of Toronto researcher has developed a flat lens that doesn't respect the "normal" laws of nature and could significantly enhance the resolution of imaged objects. "The creation of an unusual flat lens may finally resolve a long-running controversy about the existence of materials that have metaphysical qualities -- so-called "metamaterials" -- that transcend the laws of nature. The lens could lead to amplified antennas, smaller cell phones and increased data storage on CD-ROMs. As says George Eleftheriades, the Toronto professor, "This is new physics." Check this column for more details and other references to metamaterials."
Original article (Score:4, Informative)
Re:Pull over, bub (Score:5, Informative)
The emphasis on the "flatness" of the lenses, at least on /., is misguided too. These are special materials, and the lenses are flat because they have to be owing to the properties of the materials, not the other way around.
Heck, there are all different shapes of lens. Nikon's been out front with consumer "aspherical" lenses for a few years now, selling them in camera lenses and relatively low-end consumer binoculars. They let you simplify things like the number of elements in a camera lens, or help with distortions on the edge of the field in binoculars. Those are all curved, still, just not spherical on the edges -- but a new shape of lens isn't really much news. It's the whacky materials that make this story.
I guess it's science reporting, so let's take what we can get.
/shrug
New Scientist makes fact sound like fiction (Score:4, Informative)
U o T Press Release (Score:3, Informative)
-PCB
bad science, or just wierd science? (Score:4, Informative)
Initially, you see n defined as c/v, where v is the speed of light in the material. Since v is less than c (always) this number is always greater than 1 except for vacuum. This is where the 'wierd science' part comes is, and the fact that you're only getting a fraction of the picture. In reality, n has both real and imaginary parts - the imaginary part decribes the 'folding' or how much the wave magnitude decays in the medium over distance and time. For example, if you took something that measured the intensity of light outside in the sunlight and compared it to the intensity of light behind a window in a house, the intensity *inside* would be less because the glass absorbs a certain amount of energy of the light as it passes through. As you can see, this 'n' thing is a little more complicated than what you learned initially in high school and college - end result, well, they sorta lied to you. In fact, the above is just scraping the barrel because you're still trying to give physical credence to a mathematical model.
The 'bad science' comes from putting too much faith in what the math really means. Guys, math is just a tool to *model* reality. If you put too much credence in it you start to think that stuff like virtual particles and feynman diagrams are real. They aren't. They're a tool used by physicists to get an answer that agrees with experiment. For more info on negative index of refraction stuff look at what these guys [ucsd.edu] did, and also look here [aip.org] for a little more info.
Not that it isn't cool to hope that things go faster than light and that we're just getting part of the picture...
More info (Score:5, Informative)
First off, the article mentions three properties: permittivity, permeability and refractive index. To keep the discussion simple, lets only consider refractive index, which is negative here.
So what does that mean? It in some sense it means that light is traveling backward in such a material. Not in the reflected sense of backward, but in the time reversal sense. For example, lets say you have light from a light bulb incident on such a material. In air, the light is divergerging (spreading out) from the light bulb. When the light enters this material, it no longer is diverging, but it is instead now converging.
It's certainly not hard to think of a different way of making light converge: use a lens. Indeed, at first glance a material with a negative index of refraction would seem to act very much like a lens. However there are some important differences.
In particular, lets say you wanted to make a very small spot of light (useful for reading CD's, or making IC's). A lens can at best focus light down to a spot roughly equal to the size of the wavelength of light. (This is why blue lasers are wanted for advanced CD/DVD's: shorter wavelength gives a smaller spot which gives greater density). A material with a negative index can get around this limitation.
How? There is one conventional way of making a spot of light smaller than the wavelength. That's by simply using a pinhole (or a capillary, which is esentially a pinhole with a funnel to push more light through pinhole). The problem with a pinhole, is the small spot of light only exists in the plane of the pinole. The light diverges very quickly so it's hard to do anything useful with it. (There is some interest in doing near field microscopy this way). However, if you had some of this magic material, you could recreate the small spot in a different plane. (You can't do this with a lense because it is impossible to capture the entire wavefront exiting the pinhole. This material has no such limitation - you can put this material right up against the pinhole).
This explains why this material might be interesting for CD technology. I have no idea about the other applications they mention.
Re:The BS Detector (Score:2, Informative)
"Light passing through a flat glass lens will diverge." - Light passing through a flat glass most certainly will diverge, just like light passing through air diverges. Refraction (such as in a curved glass surface), and diffraction (such as in a hologram) can be used to refocus or make light converge.
"allows focusing almost two orders of magnitude higher than is possible with conventional lenses'..." - This one does have a bit of hype, but it could be correct if you consider spot size the figure of merit. See my comment below with the subject "More info". Ditto for the next quote you pulled.
As far as flipping signs in long-accepted equations, that's exactly what's special here. They've simulated a material which actually has the properties that these signs flip! (Similar materials have been experimentally verified by others). The answer to part 2 of your comment is "no". No conventional optical system provides a means to do what is happening here, although lenses have some similar properties.
I'm not sure about the Scientific American artilcle of which you speak, but it is very likely they are related. I'm not really sure what is new in this article. As you point out, this article is high on hype and low on facts/details.
New website to /. (Score:2, Informative)
metamaterials.net [metamaterials.net]
From this article [146.48.75.78]Here are the papers (Score:3, Informative)