All Questions
Tagged with optics optical-materials
157
questions
116
votes
6
answers
115k
views
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 ...
- 5,377
36
votes
4
answers
5k
views
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 ...
- 8,230
29
votes
7
answers
5k
views
Why don't opaque objects reflect light?
My sister was doing a quiz and I tried to point her in the right direction by giving her scenarios to imagine. One of the questions in the quiz was:
Which of the following objects do not reflect light:...
- 1,289
20
votes
2
answers
25k
views
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 ...
- 3,348
19
votes
1
answer
2k
views
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 ...
- 4,788
11
votes
2
answers
2k
views
What percentage of light gets scattered by a mirror?
Sunlight strikes a mirror at a 45 degree angle. The vast majority of light will be reflected about the normal. Some light will be absorbed by the mirror. Some light will be transmitted through the ...
- 912
11
votes
1
answer
356
views
How do non-mechanical solid-state optical switches work?
I am currently looking for a fiber-optical switch (FOS) in order to be able to change the light source of a spectrometer. As this will be used in harsh conditions, I was hoping to find a FOS with no ...
- 213
8
votes
2
answers
458
views
What are the current experimental limits on the polarizability of the vacuum?
Many (all?) materials are polarizable at some level; meaning that when we apply an electric field across the material, there is an induced dipole moment
$$
\vec{p}=\alpha(\omega)\vec{E},
$$
where $\...
- 7,063
7
votes
2
answers
1k
views
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 ...
- 758
7
votes
1
answer
482
views
What is the energy loss in total internal reflection?
In total internal reflection light inside a dense medium reflects from the boundary to a less dense medium. Since by Snell's law there is no allowed refracted ray, all energy continues along the ...
- 32.9k
6
votes
2
answers
2k
views
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,...
- 161
6
votes
1
answer
293
views
Why is $\textbf{D}$ the response to $\textbf{E}$?
In the text Wooten, equation 2.69 shows $\textbf{D}$ being the response to $\textbf{E}$ with $\epsilon$ as the response function:
$$
\textbf{D}(\textbf{r},t) = \int d\textbf{r}^{\prime} \int dt^{\...
- 87
6
votes
0
answers
245
views
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 ...
- 6,273
5
votes
2
answers
4k
views
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?
- 51
5
votes
1
answer
308
views
Optical Retroreflectors: How Are the Faces So Accurately Righted?
This question is about Optical Retroreflectors (corner cubes) and how the extreme precision in their manufacturing is achieved. I suspect there is interesting basic physics involved, which is why the ...
- 88.5k