# Tag Info

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The triple dots denote a tensor-contraction over three indices. This is a generalization of the notation for the scalar product (which is contraction over one index). The three adjacent terms $E$ are implied to form a tensor product. $\chi^{(3)}$ is third order term of the perturbation expansion of the full (non-linear) susceptibility (more specifically ...

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The first diagram red vaaaal listed, unfortunately, is one of the leading causes of misunderstanding how rainbows are formed. It isn't wrong, but it suggests that red light is deflected exclusively at 42°, and that each color has its own exclusive angle. But it is easy to see, if you look, that light that is originally headed straight for the center of the ...

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$I_0$ is the intensity of light before it hits a polariser the original intensity of the beam, so called. You need it because you need to compare it to the intensity after it exits the polariser so that you can calculate your fraction of incident intensity. this fraction requested by the problem is $I\over I_0$, but $I$ refers to intensity of light exiting ...

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...couldn't I use a retarding film of randomly varying thickness to convert a Coherent laser beam into an incoherent laser beam to improve eye safety? Absolutely not. A beam's destructiveness to the eye depends on three things: Energy delivered to retina and the time periods it is delivered over, quantified by the ISO60825 concept of Maximum ...

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Couldn't I use a retarding film of randomly varying thickness to convert a Coherent laser beam into an incoherent laser beam...? If the film is not changing (in time) you are not changing the coherence properties of beam at all. You can think of putting a slab of something in the way as putting a really bad lens (possibly with no optical power) in the ...

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Yes it does. Since the direction of the light beam changes with reflection also the direction of polarization. This is mostly because the observer is in a fixed coordinate system and the light beam changes its local coordinate system during reflection. For an idealized reflector and an observer which moves along with the light beam, the direction of the ...

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Finally found out, what I was getting so confused about, here's the answer (credit to Dr Sebastian Steinlechner) with a relevant diagram. The incoming light is assumed to be unpolarised. We can, however, describe it as a combination of two orthogonal polarisations: one is polarised in the plane of incidence (the arrows in the picture), and the other is ...

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The only thing I can think of being true black would probably be a black hole. As light does not bounce off a black hole.

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The problem with the suggestion of using polarization is that you now have the reflections off the polarizers to contend with. I think the short answer is "it depends on how 'black' you want it to be". "Truly black" = reflectance of 0. I am quite sure that is impossible - there will always be some probability of light scattering off a surface. All you can ...

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There are two general classes of polarization. Plane polarization where the electric field is in a plane. Glare reducing sun glasses use plane polarizers because reflections of water and other smooth surfaces are polarized due to Fresnel's laws of reflection. The second type of polarization is circular or more generally elliptical polarization. The plane ...

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The two lenses in modern 3D glasses are designed to select the two circular polarizations. The left lens only transmits left-circularly polarized light and the right lens only transmits right-circularly polarized light (or vice versa). The problem is that there is no material which acts as a circular polarization filter on its own. The way in which they ...

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