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More on Lenses with a Negative Index of Refraction
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."
Maybe it's just me, but every other invention and discovery means, along the other things, smaller cellphones.
It is impossible to transcend the laws of nature. You can only determine that your understanding of nature has changed.
Nick Powers
Encryption: I may not agree with what you say, but I will defend your right to encrypt it...
'Metamaterials" are not "metaphysical", in the same way that metainformation is not inherently metaphysical. Meta is--say it with me people--just a prefix meaning (from the jargon file) "one level up" or if you prefer (from websters) "between, with, after, behind, over, about, reversely".
Metamaterials are carefully constructed arrangements of regular materials, whose properties combine to produce behaviours that no "pure" material can duplicate, including negative indexes of refraction.
This should not be a surprising concept to anyone who is aware that, for example, atoms can combine form metatoms (so-called "molecules") that have all kinds of properties not found when dealing with pure elements -- and yet the laws of nature survive!
There is no transcending the laws of nature going on here.
"Just once, I'd like to meet an alien menace that wasn't immune to bullets." -- The Brigadier, Dr. Who
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
"Fundamentalism" isn't about divine morality. It's about human authority.
I hate it when science discoveries are reported in that uber-hyped style. It so obscures what the real finding actually is. It looks like they have something here, but in between the whole 'transcend the laws of nature' garbage and the 'this is so fantastic and revolutionary it will change absolutely everything' garbage, it's hard to see what they actually have.
Need a Python, C++, Unix, Linux develop
For those scratching their heads at this one, maybe I can help. (I'm not an expert in this field, but I do related work).
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.
Actually, my BS detector went off in a few places in the linked article.
"Light passing through a flat glass lens will diverge." Not on my planet, bucko.
"'allows focusing almost two orders of magnitude higher than is possible with conventional lenses'..." Exactly what numerical quantity corresponds with "focusing?"
"the amount of information that could be stored on optical media would be vastly increased..." I thought that was limited by the wavelength of light used to record and read the information.
"By reversing the mathematical signs of the three main properties of all optical materials -- permittivity, permeability and refractive index -- Veselago showed that light going one way in normal materials would reverse direction in metamaterials." 1) Sure, if I start flipping signs in long-accepted equations that describe phenomena in the natural world, I can come up with all kinds of breakthroughs - antigravity, to say the least! 2) But if I set up a conventional refractive/reflective (I specifically omit "diffractive") optical system of any sort, can't I also run the light the other way identically?
Now, I think I recall an article in Scientific American some time back about structures made up of nanoantennae whose macroscopic optical properties were counterintuitive, but I don't think what I'm reading here speaks to that.