Slashdot Mirror
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."
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.
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.