Diffraction is defined as the bending or flaring of light around the corners of an obstacle or aperture into the region of geometrical shadow of the obstacle. This flaring is consistent with the spreading of wavelets in the Huygens construction. Diffraction occurs for waves of all types, not just ...

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191 views

Why is this way of calculating the diffraction pattern valid?

I've seen that in some books (Fowles) the intensity of the diffraction pattern is calculated in the following way. We place the source $S$ and the point at the screen $P$ in the line perpendicular ...
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48 views

Seeing light source from its diffracted light

Even if the line of sight is blocked by something(like a wall as in figure) will I able to see the light source if I see the diffracted light of the source? 1.Will the observer no. 2 see the light ...
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56 views
+50

Neutron diffraction on Salty Ice VII

Can someone explain in layman's term how this figure shows the presence of Cl and Li ions in Ice VII ? What can we deduce about the crystal from this data ? The whole figure and caption are ...
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33 views

Printing zone plate with laser printer

I tried to print my own zone plates on transparent plastic with laser printer with this generator. I prepared a lot of plates with different settings - focus from 4 to 60 cm, 3 wave lengths, etc. Yet ...
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24 views

Diffraction through 1 slit - light levels at minima points are zero or somewhat higher?

During a few diffraction experiments, my partner and I realized that during a 2 slit experiment all minima points surely cannot be completely dark, due to the fact that the two light sources (1 from ...
2
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229 views

Can the intensity distribution behind edges and slits be explaint by the interaction with the surface electrons of the edges?

Reading about diffraction of EM radiation on edges, slits and multi slits as well as about electron diffraction behind a wire I came to the conclusion that the intensity distributions on an observers ...
2
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97 views

Diffraction grating from first principles

I have realised that a lot of books and online resources fail to give a detailed treatment of the derivation of the diffraction grating interference pattern. Normally only the result is stated. I was ...
2
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0answers
19 views

Circular diffraction onto uneven surface

I'm trying to figure out how to solve for a surface using a circular diffraction. I have a pinhole diffraction that I'm projecting into a surface and I'm trying to figure out how to derive the shape ...
2
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53 views

Airy Pattern as infinite sum of Fraunhoffer Patterns

Is there a way to view the Airy Pattern as an infinite sum of Fraunhoffer diffraction patterns? I don't know where the 1.22 would come from then. Is there something inherently wrong with collapsing ...
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16 views

Diffractive peak for high-frequency scattering from a sphere with small index of refraction?

How does a transparent sphere's shadow fade as $n\to 1$? Consider radiation of wavenumber $k$ incident on a transparent sphere of radius $a$ and index of refraction $n$ in the limit $ka \gg 1$. ...
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48 views

Why does fluorescence emission detector pick up second order wavelengths with first order scan, even though they have different angles?

my question in more detail and with an example: Let's say I have a 980nm laser and I use that laser to excite my fluorescent solution in cuvette. My scan range is from 300 to 800nm. If, for example I ...
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24 views

Radial Distribution Function - Structure Factor relation, deriviation help

I'm attempting to prove the relation between the structure factor and the RDF, following the deriviation here (pg 92-94). The solution this source comes too disagrees with this paper which I trust ...
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21 views

Why isn't every magnetic neutron scattering peak a nuclear scattering peak as well?

Neutron diffraction is a well-established technique for determining the magnetic unit cell of magnetic materials. The idea is that nuclear scattering gives you peaks that correspond to the crystal ...
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31 views

Intersection point of two wires

When I observe two thin wires (up to 1cm, relatively) at a distance, if those two wires are intersecting (but may or may not have physical contact) the absolute point of their intersection is ...
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28 views

Structure Factor for a Simple BCC Lattice

This is an example of a general misunderstanding I am having. The structure factor is given by $$S=\sum_{j}f_je^{i\mathbf{G}.\mathbf{x_j}}$$ where the index $j$ denotes a sum over the atoms within a ...
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30 views

Wavelength limited resolution

I've read through answers to similar questions, and I haven't been able to find a satisfying answer. I've heard it said that in order to make out something, you need to use light with a wavelength at ...
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154 views

Is Wikipedia wrong about Huygens-Fresnel Principle?

Someone posted a question about why backward waves don't exist according to the Huygens-Fresnel principle: Why doesn't a backward wave exist? In following up on this question I read the Wikipedia ...
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57 views

Fraunhofer diffraction at circular aperture - integration of bessel function

I'm trying to understand the calculation here: http://en.wikipedia.org/wiki/Fraunhofer_diffraction_(mathematics)#Circular_aperture for the solution by integration, but I plain and simple fail to see ...
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58 views

Source of a parabolic wavefront

The Huygens-Fresnel diffraction integral has been formulated for incident spherical waves. A source of a spherical wave is kind of intuitive, since the perpendicular rays of the sphere converge into a ...
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94 views

Fresnel diffraction approximation (parabolic waves)

The Huygens-Fresnel principle (Introduction to Fourier Optics, Goodman), $$ U(x,y)=\frac{z}{i\lambda}\int_\Sigma U(\xi,\eta)\frac{e^{ikr}}{r}d\xi d\eta\,, $$ where $\cos \theta=\frac{z}{r}$, shows ...
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113 views

Disadvantages of viewing a diffraction grating at larger order?

If you are using a diffraction grating as a spectrometer you are likely to use high order, because you have a better resolution (as a result of larger dispersion??). But are there any disadvantage? I ...
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235 views

I have negative slop of Williamson-Hall plot, XRD data. Is this right?

I have Ag (silver) powder sample. I measured xdd of the sample and got very good 2theta peak. Since I want to know bulk modulus and Young's modulus of Ag(silver), So, I got williamson-Hall plot ...
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65 views

Can I calculate the form of the aperture from the diffraction pattern?

As I understand, the Fraunhofer diffraction pattern of light is the Fourier transform of the aperture. More precisely, the amplitude of light would be the Fourier transform and the intensity its ...
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119 views

Rayleigh criterion for sound and parabolic microphone

Currently I am developing a parabolic microphone for a study project. I've heard and read that the maximum wavelength of sound that the given diameter microphone can focus is determined based on the ...
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278 views

Can the diffraction/interference pattern behind the slit (double slit) be calculated with Feynman path integrals (QED)?

I often see Feynman path integrals explained by a graphic which shows the slit and then the electron goes all possible ways behind the slit. Ok that is nice to understand the Feynman path integral, ...
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83 views

Reciprocal space maps units

I have seen reciprocal space maps in different units. In some figures, it is represented in delta(l) delta(h) reciprocal space maps units. In some figures it is shown in Q(parallel) and Q(normal) ...
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38 views

Modeling the diffraction of arbitrary electric fields by diffraction gratings

I have read from many sources that the Fraunhoffer diffraction pattern is the Fourier transform of the grating. But I feel like these explanations do not take into account the curvature of the initial ...
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104 views

Bandpass of diffraction grating - exit slit width?

I'm supposed to derive a relation for the range of wavelengths that's being transmitted by a spectrometer (bandpass) in terms of the dispersion, focal length and exit slit width. Given grating is ...
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293 views

Fabry Perot Etalon - changing wavelength and plate distance

Given reflectivity $R = 0.75$, an etalon is used as an interference filter, transmitting light of wavelength $4.3\mu m$ at normal incidence. The full width half maximum is about $\Delta \lambda = 0.2 ...
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115 views

Quick question on convolution - Diffraction through a pair of slits

We know that the fourier transform of the amplitude function (in terms of $y$) gives you the amplitude function (in terms of $\theta$) Consider a pair of triangular slits: Fourier transform of ...
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64 views

Optical Spectra and the Diffraction Grating

I'm doing a lab where we are identifying different gases by their diffraction spectra. This what my lab book says: Verify and calibrate your spectrometer, by measuring Hg and Ne. Measure ...
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119 views

Spreading UV light? Fresnel lenses?

I'm making a little UV exposure box and I'm looking for a way to evenly spread out the UV light. I've used Fresnel lenses to do just this in the past, but that was for visible light. But from what ...
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155 views

C Method for Diffraction grating

Alright, so I am trying to find the efficiencies of a coated diffraction grating through the method in this paper. This is through a change of coordinate system. So I went through and derived all of ...
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66 views

Is there spatial data loss in light passing through transparent crystal?

There is perfect parallelepipedal bar made of transparent crystal with cubic lattice floating in vacuum. Faces of parallelepiped are parallel to lattice axis. There is image, forming checkerboard ...
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16 views

Producing a collimated beam from a point source

I have an optical fibre of numerical aperture $NA$, of very small core radius, located at the focal point ,$f$, of a lens. I should produce a collimated beam of initial radius $f\cdot NA$. But what ...
0
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0answers
20 views

Slit width of a diffraction grating monochromator?

I am trying to find an equation for the bandpass of a diffraction grating monochromatic. I have found this source (link to google books) which indicates that it is given by: $$sD^{-1}$$ Where $s$ is ...
0
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0answers
20 views

Are k-points in the reciprocal lattice, points where constructive interference is the strongest?

I saw a video on youtube that seemed to imply that k-points are the positions where constructive interference is strongest. The link is https://www.youtube.com/watch?v=DFFU39A3fPY Is this true? I ...
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31 views

Using Fraunhofer diffraction when projecting on a curved screen

Suppose I have a slit very far away from a curved screen (suppose part of a circle). If the screen was flat, the far field approximation is due to the Fraunhofer diffraction, and is given by $$ ...
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0answers
67 views

Laser shone at liquid jet

When a liquid jet of water falls in laminar flow, it hits a surface. If this contact point, between the surface and the jet, is illuminated by a laser. Rings of light can be seen forming around the ...
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63 views

Single Slit/Double Slit path differences

When diffracting light through a double slit, I understand that the two sources must arrive on the screen m(wavelengths) out of phase [where m is any whole number], in order for a bright fringe to ...
0
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90 views

Question about heisenberg uncertainty principle and single-slit diffraction

My question relates to this video illustrating the Heisenberg uncertainty principle. The video shows light being shot through a slit forming a spot on a screen. As the slit narrows, the width of the ...
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0answers
44 views

Two-slit experiment, why $\exp(ix)$ and $\exp(-ix)$?

I am looking at an example problem from optics with two narrow slits with light shining through both. The light through one slit is 5 times the amplitude of the light through the other. I know from ...
0
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0answers
16 views

Diffraction grating with film covering half of slits

If I have a film covering part of my slit of finite width is it justified to take the integral of the wave elements with there phase difference as a function of x across each half separately ...
0
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62 views

Formula for intensity and central bright fringe in Fraunhoffer diffraction from single slit

I want to understand why, theoretically, the central bright fringe has maximum brightness/intensity. And where does the formula $I=I_0\left(\frac{\sin B/2}{B/2}\right)^2$ come from? My book says it is ...
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0answers
49 views

Is Rayleigh/Wood's anomaly simply the grazing order diffraction?

Is Rayleigh/Wood's anomaly simply the grazing order diffraction? I read some related papers but I am still confused, can I simply understand it as a surface wave propagating on the surface because of ...
0
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0answers
34 views

What are the exact setups to observe a wave function and its collapsed state?

I was reading this article: http://io9.com/5528321/how-smart-do-you-need-to-be-to-collapse-a-wave-function and I need some clarification on the experiment setup. My current understanding is that if ...
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45 views

A problem in deducing $|\psi(x)|^2 \propto \cos^2(\pi sx/\lambda z_o)$ in diffraction by two slits experiment

In Quantum Mechanics for scientists and engineers by David Miller, he explains the diffraction by two slits (page $13$) and considers a beam of electrons whose wave function is $\psi(x)= \exp(ikr)$ ...
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31 views

Determining angle of distortion in a Rhombohedral unit cell

I have a film which is rhombohedrally distorted. I would like to measure by Xray diffraction, the angle of distortion of the unit cell. I can measure the in-plane and out-of-plane lattice parameters ...
0
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123 views

Question about dark fringe in diffraction

In finding the angle for the mth dark fringe of single slit diffraction using Huygen's principle, they usually split the slit into equal portions. For example, to find the first dark fringe the slit ...
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43 views

How to design a grating coupler to produce surface plasmon-polaritons (SPPs) at a desired frequency?

Following on from this question, which I found very useful on the topic, I was wondering how you would use the equation $\beta = k sin \theta \pm \nu g$ to fabricate a grating coupler to generate SPPs ...