metamaterials / negative index of refraction

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Deus
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Post by Deus » Tue Feb 27, 2007 11:26 pm

http://en.wikipedia.org/wiki/Thin_lens_approximation

It is a model that does not use classical index of refraction calculation => there is no real "object" that the lens hits => the "lens" does not have a body that has a real IOR => I am right => You are not.

Why the hell do I spend my teaching fools?

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OnoSendai
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Post by OnoSendai » Tue Feb 27, 2007 11:50 pm

Please be polite guys.

Kyokutan
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Post by Kyokutan » Tue Feb 27, 2007 11:52 pm

I agree with Deus about the thin lense model.

But the thing with the cube with IOR 10 for the whole szene is wrong!
If the air IOR would be 10 and there is a object with ior 1 it would be the same as the air would have IOR 1 and the objekt IOR 0.1
Also this would only lead to total reflection.


http://upload.wikimedia.org/wikipedia/d ... infach.png
(Trennfläche= interface | Lot = normal)

here you can see how a material with a negativ IOR would behave.


(Sorry for pathetic english)

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oodmb
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Post by oodmb » Wed Feb 28, 2007 10:39 am

the fact that the lense does not have a body does not make putting the scene in an ior of 10 cause objects with normal iors to have 0.

also, as that picture might represent how a negative index of refraction would work in theory, it does not represent how a negative index of refraction actualy works. in fact, i do not think there is any simple explination of how they actualy work.
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Kyokutan
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Post by Kyokutan » Wed Feb 28, 2007 11:28 am

Your first sentence doesn't make any sense to me...it's a mix of the thin lense model discussion and my remark about the IOR10 enviroment.

And i know that the picture only shows the mathematic behavior of negativ IOR mediums. I read something about strange things happen in the interface, like multiple reflections...but how can you simulate something like that?

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oodmb
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Post by oodmb » Wed Feb 28, 2007 1:17 pm

yah, i agree, my first sentence doesnt make any sense to me either. i just reread it. i meant...
the fact that the lense does not have a body/model/mesh does not change the fact that putting the scene in an ior of 10 does not cause objects with normal iors to have negative iors.

if it exists, and it's not magic (well even most magic), it can be simulated on a computer. eventualy at least. what i think the negative ior medium is actualy doing is acting like it is wrapped in fibre optics and catching the ray, then bending it around the surface to the point corrosponding with the point that the light would have gotten to if it had not hit the medium, then releasing the ray at the same angle it came in. this could possibly be done by having the light enter the medium and refract in such a way that its refracted angle is the same as if there was a total internal reflection. this will happen until the ray hits a certain point. i am unsure however, why the ray would leave the medium at the end point and not some other point.
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Lord of the Rings Junkie
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Post by Lord of the Rings Junkie » Wed Feb 28, 2007 4:41 pm

POV ray appears to be able to simulate negative IOR.

link with pic

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oodmb
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Post by oodmb » Wed Feb 28, 2007 4:47 pm

wow, weird. unfortunitly, this means that if povray can do it, indigo should be able to do it, at least if the goal of indigo is to simulate light realisticaly.
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Deus
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Post by Deus » Wed Feb 28, 2007 10:40 pm

Let me try to explain once more

There is no such thing as negative IOR to start with. IOR is always relative to other IOR.

Total internal reflection occurs when you leave glass 1.5 to air 1.0 then the relative ior is 2/3.

What the original poster here wanted to achieve was "negative IOR" which means IOR <1. That can be achieved by having entire scene and camera inside a "high" IOR medium and then adding object with lower IOR and higher precedence (given Indigo doesnt bug out. I think still that the total internal reflection code/exit rays are wrong in indigo and that is why it bugs out).

Last post in this thread. Sorry if I hurt anyone ;-)

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OnoSendai
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Post by OnoSendai » Wed Feb 28, 2007 10:47 pm

Deus wrote:I think still that the total internal reflection code/exit rays are wrong in indigo and that is why it bugs out).
It would be helpful if you could actually isolate and provide a repeatable case (e.g. scene) for this claimed bug, instead of just alluding to it, Deus.

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oodmb
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Post by oodmb » Thu Mar 01, 2007 12:14 am

no dude, there is a negative ior. read the papers.
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CTZn
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Post by CTZn » Thu Mar 01, 2007 2:39 am

These materials exists, as I was saying the january 12 already.

Papers ? "The first superlens with a negative refractive index provided resolution three times better than the diffraction limit"

Applications can range from nuclear shield to invisibility cape, but as someone told already they are not working yet for the visible spectrum, only microwave and recently, near infrared. Well this year visible bandwidth were concerned (780 nm)...

Tell that guys negative ior doesn't exist =>Prized

----

What bug ? That's the third time you speak about, but Ono is right, you never treated about that seriously, Deus...

Deus
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Post by Deus » Thu Mar 01, 2007 3:53 am

Well how cool. I'd like to emulate reality when I render stuff with Indigo. Why would I need something that only works under very specific conditions in a lab? I assumed he wanted other IOR<1 to emulate being under water or something :P.

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oodmb
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Post by oodmb » Thu Mar 01, 2007 10:49 am

well, simulating something being under water i think would work, although i have not experimented with it. but negative index of refractions exist and work not only under specific lab conditions. the materials that exist would work everywhere in theory (if they were available everywhere), but only for certain frequencies of light. what the engineers behind them are currently trying to do is add more frequencies to there optical range. at the rate that they are currently advancing, we should have full spectrum metamaterials within at least 20 years. due to the fact that they only work under certain wavelengths, there is no need for them outside of a lab yet and thus there is nothing saying they work outside of the lab. yet, there is also nothing saying they dont work, and infact alot of proof and theory that they would work.

now that i think about it, if anybody wanted to render a certain scene from harry potter realsticaly, i guess mettamaterials would be necessary.
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fused
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Post by fused » Thu Mar 01, 2007 11:00 am

now its my turn to spam this topic:

LOL :lol:

8)

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