Questions tagged [optical-materials]
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26 questions
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Why is glass transparent?
Once I asked this question from my teacher and he replied "Because it passes light.". "And why does it pass light?" I asked and he said, "Because it is transparent.".
The same question again, Why ...
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If we repeatedly divide a colorful solid in half, at what point will the color disappear?
Suppose I have some colorful solid, which I cut into two halves (both are identical). Take the first and cut it into two parts, and then repeat this again and again. I know that a single atom doesn't ...
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How can the refractive index be below 1 in a dielectric?
Upon checking the optical properties of different dielectrics, I found the interesting case of $Al_2O_3$. It seems to be reported with a refractive index below 1 in the infrared range of $10 - 12~\mu ...
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Why is diamond transparent while graphite is not?
Diamond and graphite are both made of the same atom, carbon. Diamond has a tetrahedron structure while graphite has a flat hexagonal structure. Why is diamond transparent while graphite is not (at ...
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Are there yet Optical Magnetic Mirrors (OMMs) which reflect via interaction with the magnetic field?
update 2021: As the question has remained unanswered for five years and the field of optical metamaterials has advanced, I think this question can be revisited.
The most familiar mirror relies on ...
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Why does optical media have different refractive indices?
Optical density is a measure of the refracting power of a medium. In other words, the higher the optical density, the more the light will be refracted or slowed down as it moves through the medium. ...
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Ideal surface for a perfect lens
in this physics lecture, on slide 15-16, it is found that the ideal surface for a perfect lens (which maps a plane wavefront into a perfect spherical wavefront, i.e. which makes focus all input ...
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Why are the edges of a broken glass almost opaque?
Unfortunately I broke my specs today which I used in this question.
But I observed that the edges are completely different then the entire part of the lens. The middle portion of the lens was ...
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Is the visible light spectrum from "red-hot glass" at least close to Blackbody Radiation?
Briefly, for visibly transparent materials like glass, you can see through then even while they are glowing red hot. Most glasses have plenty of absorption in the IR, so there is plenty of absorption ...
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Why do everyday plastic items interfere with light polarizers?
I recently bought a few pieces of linearly polarized film (the one intended for smartphone LCD screens). At first I was confused because I could not make the polarizers work as they should - no matter,...
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Are special relativity calcs affected by media?
Time dilation, increase in mass, Lorentz contraction calcs all involve velocity of light in vacuum. But in optical media light slows down. So what of relativity calcs in media? Do we ever need to ...
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Slowing down light in an opaque crystal for a whole minute
I just read about a team of physicists at the University of Darmstadt, Germany, that managed to completely slow down a beam of light that traveled through an opaque crystal (article here).
How is it ...
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Why can't ultraviolet light pass through glass?
What factor determine whether a body behaves like a transparent object for EM waves of a particular frequency?
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Why are there direct bandgaps?
This Question has been bugging me for sometime. Some semiconductors have direct bandgaps and indirect bandgaps. So what causes a direct bandgap to occur? The physics behind ,why there are direct ...
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What plastic-like materials allow IR to pass through them? [closed]
What plastic-like materials allow IR to pass through them?
Material should be solid and plastic like. Does't care if it is transparent to light or not.
IR ray is emitted by Sharp distance center so it ...
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Does temperature affect the index of refraction?
I would like to know the physical reasoning behind the fact that temperature indeed does change the index of refraction of a certain medium.
(Is there an easy experiment for me to try this at home?)
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Are there any real-world examples of refraction of light by magnetic permeability?
The question Fresnel Transmission Coefficient for Magnetic Field is interesting.
Thinking about it led me to reflect upon what little I know of the history of optics, with refraction by lenses and ...
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What is the mechanism of transparency of EM?
What happens in transparent materials? Do their molecules oscillate with the same frequency as the EM wave and then reemit in the same direction? Or the light goes through meshes in the bulk?
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Is it possible to make an optical lense that is an analog to a gravitational lense?
There are many lenses that do all sorts of things. eg. horshoe lenses twist light, meta material lenses can boggle the mind.
Is it possible to make an optical lense that is an analog to a ...
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Metamaterial : Snell's law and Fermat principle
How do we deduce Snell's law using Fermat's principal in case of metamaterials? Metamaterials have negative refractive index. This makes the refracted ray of light bend on same side of normal as ...
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Change of refractive index using semiconductor
I was wondering, if it is possible to change the refractive index of a semiconductor using an electric field or current? I have heard about injecting charges to tune the refractive index. How/Why does ...
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Visible light through a single-mode optical fiber?
If I understand things correctly, the optical fibers used for (long-range) data transmissions are generally single-mode fibers, transmitting light in the 1300-1500 nm spectrum.
Now, could such a ...
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Exactly which objects should we considered as colorless? [duplicate]
My question is which objects are considered as colorless?
In chemistry we sometimes consider white object as colorless,Many times we use the word colorless for transparent substances like water, glass,...
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Can a photographic film on a flat slab create a well visible elongated picture of a far and faint astronomical object? [closed]
Let say we see a light source with apparent cross section area 1mm squared. If we position a flat slab with inductive high light sensibility at a very small angle to that source one dimension of the ...
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Which coefficients are needed to numerically obtain transmission spectrum?
I'm using Omnisim program. I would like to obtain transmission spectrum of certain material so I have created two polynomials: one representing real refraction coefficient and one representing ...
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Do III-V based photovoltaics "glow" (photo-luminesce) when illuminated but not loaded?
In this nice answer I started to learn about how the silicon photovoltaics cells on the International Space Station are managed. In that case, the cells are generally either delivering useful power to ...
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