All Questions
Tagged with refraction optics
916
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Luneburg lens in a medium
A Luneburg lens is a spherical lens with a gradient refractive index. It has the interesting property that light coming from focal length of infinity will be focused on the surface of the lens.
The ...
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What is meant by optical density?
I’m trying to research about optical density for a school task, but the definitions online are confusing me.
From what I’ve gotten, optical density is:
how much the intensity of light is increased or ...
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2
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123
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Diffraction when the wavefront is not parallel to the plane
I am studying Feynman's chapter on the origin of the index of the refractive index (see this link).
If I am not mistaken, what he does is to prove that when a wave enters a medium (modelled as a ...
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Snell's law in materials having negative permittivity only?
We have reverse Snell's law in negative index materials (having negative permittivity and permeability). If we have a material with only negative permittivity , then can we also have reverse Snell's ...
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Most generic form of refractive index tensors
The refractive index of a material is in general a $3x3$ tensor (as in the case of birefringent crystals). From literature, it seems that in the case of transparent crystals, this tensor is in general ...
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Relating Brachistochrone problem to Fermat's principle of least time [closed]
When I came across the Brachistochrone problem, my teacher said we could relate it to Fermat's principle of least time.
So, we could make many glass slabs of high $\mathrm dx$, and every slab has a ...
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2
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231
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Huygens' principle and the laws of reflection/refraction
As I understand the Huygens principle, all points on the wavefront are sources of secondary spherical wavelets and the tangent to these wavelets will form new wavefront. This is used to prove the ...
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Is there a good quantum explanation of refraction? [duplicate]
I'm aware of the classical explanation of refraction which deals with light being a wave that gets "slowed" down while passing from a medium to another. One problem that I have with this ...
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At which wavelengths do photons behave like X-ray?
Hard X-rays of wavelengths of about an angstrom are very different than regular lights in a way that they can’t be reflected or refracted, which means their refractive index is always close to 1 ...
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2
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135
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What does the optical Hamiltonian mean?
So I was trying to demonstrate Snell's law with Hamilton's equations, and when I got the Hamiltonian:
$$H = -\sqrt{n^2-p_{1}^2-p_{2}^2}.$$
I had a question about what this Hamiltonian indicates. I ...
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Inconvenience of speed of light in optic fiber
As far as I'm concerned, optic fiber is great in order to transport information quickly using light. Since light needs to undergo total internal reflection every single time it hits the walls of the ...
- 1,616
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How to Calculate Focal Length when in another medium?
How do you calculate the focal length of a lens when it is placed into another medium, if I only have the focal length of a lens in the air? I understand that the lensmaker's equation should be used, ...
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What is a convex-concave lens?
I came across this term while studying for optics, and I'm unsure as to what this means. My thinking is that it might be a meniscus lens, but the text separately give two different models for each ...
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How can a greater than 1 reflectance coefficient be explained in $\rm SiC$-$\rm SiO_2$ interface?
I ran a simulation using the Transfer Matrix Method to plot the R,T and A curves for a SiC->SiO2 interface. There's a region of incident energies where the |r|^2 I get is higher than 1 and the ...
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How does Snell's law work with a complex refractive index?
In order to calculate Fresnel coefficients for layered media, we often need to calculate the angle that light travels inside a material with complex refractive index. Naturally, this is related to the ...
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Why total reflection happens at only 1 angle?
The critical angle can be intuitively understood by Snell's law.If the incident medium has a bigger diffraction index than the refracted medium then according to Snell's law the refracted ray will be ...
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How do parallel reflected rays meet to form image at infinity? If they never meet then how is image formed?
In my textbooks it is written that when an object is kept at focus, its image is formed at infinity and is real. But how is this possible because parallel lines never meet and it is necessary for rays ...
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Ray separation in waveplates
In a birefringent medium, the ordinary and extraordinary rays have different Pointing-vector directions and, therefore, different propagation directions, since the direction of the Poyting-vector ...
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Property of total internal reflection question
If I create a medium with gradually decreasing refractive index from once face at index 2.0 and other at 1.01, and show a beam of light upon the optically denser side, will there be any losses upon ...
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2
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Deviation suffered by light ray incident on a surface
Problem:
Figure shows two spherical surfaces of radii $R$ and $2R$ separating three transparent media of refractive indices $\mu_1=1, \mu_2=2$ and $\mu_3=4$. A ray of light travelling in medium $\...
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Is there a way to calculate the angle between the refracted and reflected rays given the refractive index?
Is there a way to calculate the refracted and reflected rays? I know we use Snell's law to calculate the refracted rays, but is there a formula to calculate the angle of the reflected rays, or does it ...
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Apparent position of object in bowl of water
Say you have a bowl of water and you keep an object in it. What would the apparent position of an object inside the bowl from the position of an outside observer? Will the curvature of the spherical ...
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2
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Is refraction a special case of diffraction according to the book by Charles Kittel?
Wikipedia defines diffraction as -
Diffraction is the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/...
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QFT view of lower light speed of light in medium [duplicate]
In classical EM theory, if we have a medium whose dielectric coefficient is independent of wavelengths (suppose we filter the incoming signal to a certain frequency band), then the waveform gets to ...
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4
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Why does light bend through a different medium?
How does light going through a medium make light refract? Here’s a good picture :
The problem with this analogy is it depends on the students or light being connected to each other and as far as I ...
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Why is the refractive index for light rays travelling in circular paths proportional to $1/r$?
While studying optics, I came across a problem with solution in which the trajectory of light rays was known—circular paths around a fixed point in space, and the question was that of determining the ...
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1
answer
89
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Why do highlights occur on edges? [closed]
When looking at an object, the highlights are usually on the corners and edges. Highlights can occur anywhere on an object, but it seems like the brightest parts are where it is the most sharp.
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123
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Wave propagation in inhomogeneous media
There is a problem I'm trying to solve for some time now and is about the standard (?) approximation that it is made when one tries to solve the Helmholtz equation in inhomogeneous media, that is
\...
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Can anyone explain convergence of parallel rays on the focus of a parabolic reflector using Fermat's Principle?
Can anyone explain convergence of parallel rays on the focus of a parabolic reflector using Fermat's Principle? using optimization techniques from calculus?
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Microscopic model of complex refractive index
In my Electromagnetic Optics class, we tried to reconcile the microscopic (optical) properties of matter with its macroscopic counterparts, and one of the most challenging properties is the (complex) ...
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How does an electromagnetic wave behave when it enters a medium with refractive index less than unity?
From what I am able to find, the phase velosity of the wave exceeds c, but the group velosity remains less than c. However, why does the wave form wavepackets after entering a medium with refractive ...
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Finding the limiting refractive index of a rainbow
Give the limiting refractive index of a rainbow.
The raindrops are modelled as spherical droplets, with refractive index $n$, with parallel rays from the Sun incident on it. I have a very limited ...
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Minimum Radius of Curvature an Optical Fiber can be bent
Using the thickness and refractive index of an optical fiber, is it possible to know the maximum radius of curvature it can be bent before there are losses due to refraction?
In my research, I came ...
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2
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Why does laser light not bend (refract) when it travels from air to water?
I passed green laser light from air to water but to my suprise the light doesn't bend towards normal even though I changed the angle of incidence.It goes undeflected ,Is it because of its higher ...
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4
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643
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Refraction of light through a slab of variable refractive index
Here I am posting a question of Jee Adv. 2023 based on refraction.
A monochromatic light wave is incident normally on a glass slab of
thickness 𝑑, as shown in the figure. The refractive index of the ...
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1
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2k
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How does a Magic Mirror work?
I recently found out about the Magic Mirror. Both sides of the mirror look the same, and it appears to be dark, if looked at closely, like sunglasses (but lighter in colour) but looks like a normal ...
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When light passes from one medium to another. Depending on the density, it would experience a change in velocity. Why would its vector change as well?
For example, when light passes through water its velocity decreases and refraction occurs. Why? Why is there a change in direction. If I slow down a car I don’t suddenly turn left.
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What causes light to scatter in a medium?
My understanding is that all mediums have a complex iindex of refraction where the real component is the "standard" index of refraction, and the imaginary component is the extinction ...
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Refractive index of air & pressure relation [duplicate]
I do not understand why refractive index of air,when nearly equal to 1,is proportional to the pressure of the air.
If anybody can provide an answer with proper resource from which I can study on the ...
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1
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184
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Complex Refractive Indices, Absorption, and Transparency
A complex refractive index is defined as $n = n_0 + \kappa$ where $n_0$ is the "standard" refractive index, and $\kappa$ is the optical extinction coefficient. The optical extinction ...
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201
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Lenses and missing reflection
I am wondering why reflected rays are not considered with lenses. If a ray strikes a surface, another is reflected off that striking point; however, this is not added when studying lenses, only ...
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Fresnel Equations and an Opaque Surface?
I'm trying to make sense of what actually happens to light when it interacts with an opaque surface.
The fresnel equations give us the proportion of light which is reflected off the surface of a ...
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75
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Perceiving the rainbows
Famous Astrophysicist Dr Neil DeGrasse Tyson, explains that whenever we observe a rainbow it appears exactly semi-circle to us. If another person is observing the same rainbow from a slightly ...
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The speed of light in medium with different frequency
We know that the speed of light in vaccuum can be expressed as $c=\frac{1}{\sqrt{\mu_0\epsilon_0}}$ and thus the speed of light in vaccuum is thus $$v=\frac{1}{\sqrt{\mu\epsilon}}=\frac{c}{\sqrt{\...
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2
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Geometric optics multiple lens focal length calculation
Just wanted to understand how I would go about calculating the effective focal length of these different lens configurations.
There's the combined focal length formula, but I'm struggling to apply it ...
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209
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Do high powered lasers refract differently than other light?
So I have a question: I am told that there are naval lasers that target over 100's of miles ship-to-ship (not ship to air). Someone asserted that powerful lasers would refract differently than light. ...
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Photon momentum in Snell's law of refraction
In the drivation of Snell's law for light as EM waves, we have the wave vector components parallel to the interface $k1\parallel$ = $k2\parallel$ as shown in the picture.
From $k_{1x} = k_{2x}$, we ...
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Snell's Law- Extraordinary ray
I applied the snell's law to find the angle of refraction of the Ordinary and Extraordinary ray. And I got the correct answer 3.51. But I know my approach to the question is wrong because I applied ...
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102
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Can the refractive index of a medium be negative?(<0)
Recently I was asked in a test what would happen if the refractive index of a medium was negative. Is it possible really? The refractive index is the ratio of the speed of light in a vacuum and ...
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Shift in image caused by refraction in normal image formation and shift in fringe (youngs double slit experiment)
for shift in a image from its original position due to a slab of thickness $t$ and refractive index $u$ is given by $shift(s)=t[1-1/u]$
and for shift in fringes formed during youngs double slit ...
