Team produces weird optical phenomena - and rewrites the rules of refraction | Hacker News Reader

Team produces weird optical phenomena - and rewrites the rules of refraction

tgdaily.com

29 pointsrickdale11 comments

Interesting stuff, but to me it's a bit of a stretch to say that they've rewritten the rules of refraction, since the basic laws assume ideal interfaces between media. What they've actually done is created a material so exotic that that abstraction is no longer sufficiently accurate to describe it. I imagine QED (http://en.wikipedia.org/wiki/Quantum_electrodynamics) still holds.

"[I]t's a bit of a stretch to say that they've rewritten the rules of refraction."

Indeed. It appears more akin to the situation we have with classical and quantum mechanics: classical (Newtonian) mechanics fairly accurately describe the behavior of macroscopic objects at relatively slow velocities. We acknowledge that the system is not valid outside of that range. But since that range encompasses the bulk of our everyday, practical experience, classical mechanics are exceedingly useful.

Classical optics are not suddenly outdated with these discoveries. Snell's law and the lens-maker's formula are just as relevant as they were yesterday. We just need to add a few more terms to the equation if we etch a gradient of nano-scale resonators to the surface of our optical element. (Boy, do I feel like Geordi in Star Trek reading that last sentence aloud.)

Negative index of refraction materials are not quite new: wikipedia indicates that they are already being used in commercially-available products (http://en.wikipedia.org/wiki/Negative_index_metamaterials). For me, the most exciting application is creating a lens that circumvents the diffraction limit that limits optical imaging resolution. Right now, the most sophisticated, expensive microscope objective lenses can just barely resolve sub-cellular structures only under very particular conditions (i.e., not alive). A diffraction-unlimited "superlens" made out of this stuff could enable us to see even smaller objects under physiological conditions. It would be fantastic if we could capture the release of individual neurotransmitter vesicles at a diseased synapse, for example.

Besides negative index materials, there are a whole class of non-linear optics (http://en.wikipedia.org/wiki/Nonlinear_optics) that allow engineers to do all sorts of funky things in their instruments, like doubling the light frequency or self-focusing.

This actually sounds both revolutionary and immediately practical for lens design. Covering lens with gold nano antennae sounds expensive, and I assume the surface is delicate, but thin spectacle lenses and super lightweight camera lenses are an obvious result.

absolutely. you could make much more compact "telephoto" lenses too. or connect "bifocals" to the nerve that controls eye focussing and have glasses that automatically focus to the correct distance (yes, i am getting old). or stationary solar collectors that adjust to the moving sun (or that still move but self-correct for distortions and support flexure). or a new kind of electronic ink. or...

this is huge, yet the report covers just silly mirrors... weird.

Many of those ideas require not only that we can make this stuff in bulk at low prices, but also that we can dynamically change the stuff after production at high speed. I did not read that in the article. Did I browse it too fast?

ah. maybe i misread the article. where it says antennas i assumed they were active. but if they're just passive (conductive) elements then you're right. i guess that is more likely :o(

[edit:] that would certainly explain why they only mentioned silly mirrors!

The lenses can be passive and thin, which is all you need to make camera or spectacle lenses.

Isn't a fresnel lens really just an non-idealized boundary layer too? http://en.wikipedia.org/wiki/Fresnel_lens

Correct, but with the caveat that it only really works along the optical axis. Off-axis you get horrible artifacts. If I recall correctly these metamaterials do not have that limitation.

How is this new? Surface plasmon resonance effects with gold are, I'd thought, an exciting but well-understood phenomenon in nanotech.

Using gold nanoparticles to achieve unique photonic effects has been done since the Roman Empire and the Lycurgus Cup (this artifact used relativistic behaviors of gold to show two different colors, depending on the light source being either reflected or refracted)

I'm not sure this rewrites any rules, it seems "just" nanooptics when surface structure with patterns below the wavelength of the light is reflecting, refracting or diffracting the light.

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