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Questions tagged [diffraction]

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 light.

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How can I focus a laser in the gap between two slits?

I’m trying to focus a green laser in between two slits. The slit width is 0.2mm and gap between the slits is also 0.2mm. I measured the laser’s minimum spot size. It’s elliptical with major and minor ...
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What is the phase difference in a double slit Fraunhofer diffraction? [on hold]

In fraunhofer diffraction, the source is placed in the focal plane of a convex lens and the screen is placed in the focal plane of another lens. The combination of the 2 lens makes the distance ...
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Why are experimental atomic scale images black and white?

XRay diffraction patterns are black and white. So are scanning electron microscope (SEM) images. Why is this so? At the time of measurement at the atomic level, do the atoms fail to absorb or emit ...
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Feynman Lectures Vol. 1: error in the formula for resolving power?

In chapter 27 of Feynman Lectures on Physics Vol. 1, section 7 on resolving power, Feynman states the rule for optical resolution: two different point sources can be resolved only if one source is ...
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Why do the two slits of a double slit experiment not make light coherent and create an interference pattern if monochromatic light is passed through? [duplicate]

If a narrow slit makes monochromatic light coherent, why is light required to pass through the single slit before the double slits in Young's experiment? Wouldn't the double slits individually make ...
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Holographic “lens” - controlling light diffraction angles with silver halide film

I'm trying to develop a way to control the "exit angle" (diffraction angle) of a monochromatic light source. For example: taking a laser; spreading the beam; and directing the light at a piece of ...
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Diffraction of White light: Why is violet on the inside

When white light is passed through a diffraction grating, an interference pattern is observed. The center will be white as the path length is equidistant however the edges will be rainbows. What I don'...
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What frequency range can be tolerated with Young's fringes? (Problem 9.4, Brooker, Modern Optics)

I am having problems with part 2 but provided part 1 for context - I believe I have part 1 correct but could be mistaken. Let a Young-slits apparatus have slits separated by d. Let the incoming light ...
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Angular width of first maximum in diffraction grating

Often in my book they have referenced the fact that as N (the number of slits) becomes very large, the angular width of the first maxima in a diffraction grating can be approximated as follows: I am ...
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Help understanding resolution between two light beams

Today I read that if you have two light beams with a wavelength difference equal to $\Delta$$\lambda$ to resolve the two into two disjoint spots, the following must be true: Where N is the number of ...
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Question about the derivation of the intensity formula of a diffraction grating

In the notes I have, they have a diffraction grating with $2N + 1$ slits, a slit width of $2a$ and a slit spacing of $d$. They then say that the equation for the diffraction intensity pattern is given ...
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Scattering on crystals beyond Ewald and Bragg

So I whenever we consider the diffraction and scatting using crystals, powders, basically anything crystalline in the lab using X-rays we get a bunch of theories and models. The most simple one would ...
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What is the reason behind diffraction of light?

What is the actual reason behind diffraction of light? I want to know how is the phenomenon diffraction explained theoretically in physics (best if the discussion limits itself to classical physics). ...
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What is the physical meaning of Green's theorem and Green's identities?

During the derivation of Kirchhoff and Fresnel Diffraction integral, many lectures and websites I found online pretty much follows the exact same steps from Goodman(Introduction to Fourier optics) in ...
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Angles of diffraction orders in hexagonal grating

I have a situation of normal incidence where I need to calculate the the angles of different diffraction orders from a hexagonal grating. How do you go about deriving the grating equation for this ...
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Diffraction Efficiencies and Evanescent Waves

For a binary phase grating (duty cycle = 0.5, phase contrast = $\pi$), the diffraction efficiency $\eta_q$ for an odd diffraction order $q$ is given by $\eta_q = \left( \frac{2}{\pi q} \right)^2$ (see ...
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A confusion regarding the single slit interference

So I came across the single slit interference in which a parallel beam of light is passed through narrow slit as shown in figure below. (I made only 3 rays in figure for simplicity there are actually ...
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Intensity pattern in a single-slit diffraction

In a single-slit diffraction, what happens to the intensity pattern if the slit width becomes narrower and narrower?
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What is “quantized momentum transfer”, and can it account for the double-slit experiment?

In https://www.sciencedirect.com/science/article/pii/S0378437109010401, the author claims that the interference pattern obtained in the double-slit experiment does not need a wave description of ...
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Question about the integrity of a TEM analysis result

I have a question concerning the integrity of a particular TEM analysis that was done. The specimen was household dust that may or may not have contained asbestos, and was sampled with Ghost Wipes, ...
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Elastic X-ray diffraction: Where does the Photon Momentum go to?

lately I was discussing the following situation. Let's suppose you are doing X-Ray diffraction experiments on a crystal. So what you basically do is shooting a high energy photon with a wave vector $k$...
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Question about the diffraction of electrons

This question concerns the diagram on the left. This is the set up. My question is that, why is collector current not an increasing function of the KE of the electrons? I can understand the graph ...
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How is Bragg's Law related to the Phenomenon of Diffraction?

As far as I understand, bragg reflections is a geometric result which says that parallel x ray beams that are incident on atomic planes will constructively interfere at specific angles. Where does ...
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Is it possible to make a source of light such that it only emits one ray of light?

I am just a high school student trying to self study, so please excuse me if you find the question silly. I don't really need to explain my question.I am just asking if we can make a source of light ...
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What is the theory behind Fresnel's half period zones?

I was not convinced by exactly how does this work,why do we need to take concentric spheres around point P and how do those spheres cast circular areas on the wavefront? Why is the radius OM1 and the ...
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Why is a maximum value of current observed in Davison and Germer's experiment?

While studying matter waves, we were discussing Davison and Germer's experiment on electron diffraction when we learnt that a maximum value of current (measuring the intensity of electron diffraction) ...
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Why do we see a rainbow of colors reflected off a CD or DVD?

So, we all know if you shine some light on CD (compact disc) or DVD, you can see all the colors from red to violet. What is bothering me is what is the reason of why do we see the colors on compact ...
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Explanation of problem 2074 in Lim-Yung-Kuo's Problems and solutions in Optics

A pinhole camera consists of a box in which an image is formed on the film plane which is a distance P from a pinhole of diameter d. The object is at a distance L from the pinhole, and light of ...
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Change in position of maximum with the angle of source light in YDSE

One of my friends named Karan, asked me the following question: This question puzzled me for an hour. (an hour is much when your Boards exams are the next day) I want to know how I can accurately ...
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Pump Probe Spectroscopy using in ultrafast diffraction

I am going through currently the experiments on "Ultrafast Diffraction". Would you please explain with some significant degree of conceptual details how I can find the transverse Doppler shift ...
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How loud does a sound need to be to make pressure waves detectable by a camera?

I've seen Veritasium's video that describes how sound can be picked up by a camera by observing small movements of objects sensitive to pressure changes (bag of chips, aluminium foil, paper...). That ...
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Why is the central maxima of single slit diffraction pattern wider than other fringes?

I had answered a question Single Slit Diffraction Experiment, telling why the central maxima is the brightest one, but it asks: Why is the central maximum twice as wide as the others? Now, that is ...
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Origin of XRD Peak Asymmetry

I have been doing an introductory XRD experiment in which we measure the crystal spacing of a simple lattice (LiF) and as usual obtained data for intensity against two theta. Ideally the peaks should ...
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Single Slit Diffraction Experiment

How is possible for an interference pattern to be created from a single wave? Why is the central maximum twice as wide as the others?
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How do I calculate the integral for the point spread function of an optical system without the fresnel approximation?

For an object located at the $(x_o, y_o)$ plane, and a lens located at the $(x, y)$ plane, the image is produced at the $(x_i, y_i)$ plane. We can consider the image field $U_i$ to be the sum of the ...
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Is the second diffraction order at different wavelength?

If a monochromatic laser light of wavelength $\lambda$ is incident on a diffraction grating of period $A$, then does the second ($m$=2) diffraction orders have same or different $\lambda$? From the ...
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What is the theory behind imaging a precision pinhole?

In my efforts to characterise a 0.67 NA microscope objective (working distance of about 15mm, effective focal length of 25mm), I have placed a 20 micron precision pinhole at the focal plane of the ...
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Why does light keep it's direction when passing through glass?

It is assumed that light does not propagate through a different medium as such but by interacting with electrons of atoms it reaches. So photons crash into electrons of the medium's atoms, elevate ...
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How does a recordable CD that uses organic dyes to store data produce iridescent rainbow colors?

I thought that only pressed pre-printed CD-ROM can produce rainbow colors due to the parallel spiral tracks of lands and pits it uses to store data in the reflective metal layer, tracks that diffract ...
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Which focal length is needed to determine minimum focused spot size in 2 lens system?

If you calculate the minimum spot size of a beam, it depends on the focal length to to power 2. But if you have a lens system with 2 lenses, does the focal length in this case represents the effective ...
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Wave scattering by crystals

The structure factor is defined as (assuming orthogonal axes): $$S_{(hkl)} = \sum_{j \in \mathcal{U}} f_j \exp\{2\pi i (hx_j+ky_j+lz_j)\},$$ where $\mathcal{U}$ is a unit cell of the lattice and the ...
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What is the purpose of the slit in a spectroscope?

I built a spectroscope using a CD as diffraction grating. I understood how the grating works, but I didn't get why the slit is essential. Shouldn't it work even without the slit?
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What is the principal cause of diffraction?

I have found another question similar to mine here. But I want to know why does diffraction of light happen in the first place. I have found other resources on google which explain the topic partially ...
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Fraunhofer diffraction problem in Python: How to interpret discrete Fourier transform (DFT) spectrum?

I have a periodic phase grating consisting of lenslets along the x-direction, invariant in y. I want to use python to calculate the far-field (Fraunhofer) diffraction pattern that one gets when ...
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Electron diffraction on crystal lattice

To observe electron diffraction, we standardly let its wavefunction pass trough a crystal lattice. However, why does not the electron's interaction with crystalline atoms cause wavefunction collapse?
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How is the diffraction (or interference) pattern in this photo explained?

I noticed the above photo on a website (https://www.aapt.org/Programs/contests/pc09full.cfm?Meeting=SM09&Category=Natural&Placing=44). How the pattern can be explained bothers me for some time....
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Diffraction of Sound Waves

We know that Sound waves are Longitudinal waves. It mean that there is pressure difference created when medium particle move. But while diffraction of sound waves 'How will the medium particles move'. ...
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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 ...
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Do black holes have Arago spots?

I've been reading about Arago spots and the Aragoscope. Some fascinating concepts! Basically, due to wave diffraction, there is a bright spot in the centre of the shadow behind any circular object. ...
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Why is intensity decreasing for higher orders of Bragg (x-ray)diffraction?

Bragg diffraction for x-rays by a crystal structure is governed by $$ n\lambda=2dsin\theta ,$$ where $n$ is an integer and the diffraction order, $\lambda$ is the x-ray wavelength, $d$ the lattice ...