All Questions
20
questions
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30
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Polarization of electric field and its effect on the Poynting vector
To preface, I've little experience with optics. This is a very use-case specific project I'm undertaking. So, if there are any improvements in my method, I'd appreciate it!
I'm working with the vector ...
0
votes
0
answers
26
views
Near-field diffraction
I want to calculate near field diffraction loss due to the presence human blockages which are modeled as cylinders with random heights and diameters in indoor mm wave network
as mentioned in " ...
0
votes
1
answer
30
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Evanescent field, condition of $z$ component of $k$?
I am studying evanescent field and diffraction limit and I have one question.
Given a field $ U(x,y,0)$ we can decompose into 2D plane waves.
$U(x,y,0)= \int \int dk_x dk_y \tilde{U}(k_x,k_y) e^{+i(...
- 444
1
vote
0
answers
88
views
What is Raleigh expansion?
I am currently reading the paper The dielectric lamellar diffraction grating, in which the electric field above and bellow a 1D grating (grooves) is expressed as a "series of outward-going plane ...
- 111
1
vote
1
answer
168
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Fraunhofer diffraction validity and application in the far field
This question is about the Fraunhofer diffraction and the assumptions under which it is valid. My understanding is that given the complex amplitude of an electric field $E_{z=0}(x,y)$ in the $(z=0)$ ...
- 65
1
vote
0
answers
77
views
Why should the edge of the aperture have size comparable to the wavelength of light for diffraction to occur through that aperture? [closed]
I have read that diffraction of light can take place at an edge as well as through an aperture - but I never found an exact explanation of this condition. But can an edge have a size comparable to ...
- 11
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votes
0
answers
28
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Centrosymmetry in diffraction glasses
I recently purchased quirky diffraction glasses and when looking at the sun or any source of light I noticed that there is centrosymmetry.
What is this due to, perhaps the conservation of ...
0
votes
1
answer
170
views
How do the evanescent waves contribute/cause a diffraction limit?
In the following article, under the section Physics of the Superlens, it is stated:
The light emitted or scattered from an object includes not only
propagating waves but also evanescent waves, which ...
- 125
-1
votes
1
answer
153
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Is there an analytic expression for the Fresnel pattern from a circular aperture?
I am interested in the Fresnel diffraction pattern (over an entire observation plane, not just the value on-axis) due to a plane wave incident on both square and circular apertures.
I have two optics ...
- 165
0
votes
1
answer
253
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Steps to calculate the near-field diffraction pattern after an aperture (for distances so close that the Fresnel regime is not valid)?
This question has arisen out of a previous question regarding the various approximations in optical diffraction theory, and when they can each be applied.
I would like to know the steps that must be ...
- 165
4
votes
1
answer
825
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Does Fraunhofer diffraction also automatically imply that the Fresnel approximation is simultaneously satisfied?
I am confused about the regimes of validity for the Fresnel and Fraunhofer diffraction approximations, and would appreciate some clarification. Let's say we are interested in calculating the field $...
- 165
0
votes
1
answer
155
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Is diffraction empirically derived or based off something else?
after reading about diffraction I am confused on how its effect came to be understood.
Can one derive diffraction from the wave equation and base principles or is it a result of empirical observations?...
- 912
4
votes
6
answers
631
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Is it the Poynting Vector Flux or the Electric Field Flux that creates a Diffraction pattern on the back screen?
As we know the diffraction pattern from a circular hole looks something like
Intuitively I would think the "bessel function like" pattern on the right would be due to poynting flux through ...
- 49
0
votes
0
answers
169
views
Interference pattern from a diffraction on a opaque disk vs circular aperture
I have been reading up on diffraction theory and found out about Babinet's principle which states that the wave resulting from a diffraction on an aperature is the same wave resulting from a ...
- 75
0
votes
1
answer
43
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Distorsion in Photoluminescence
I am studying photoluminescence, but I do not understand why during measurement it turns out that the signal is distorted due to appearance of a long-wavelength replica of the fundamental laser ...
- 31