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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A contradiction in the Babinet principle, an even more mysterious phase difference

This is a continuation of a previous question I asked.. So, as we know the Babinet principle states that the superposition of the screen and its complement is the same as the unobstructed light. This ...
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The question about Fresnel numbers in the case of Fresnel diffraction

In the case of a circular aperture, the integer values of the Fresnel numbers determine the maxima and minima of the intensity on the axis, but can they be applied to judge the entire diffraction ...
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What is the clear difference between interference and diffraction? [duplicate]

Richard Feynman said in his book. "No one has ever been able to define the difference between interference and diffraction satisfactorily. It is just a question of usage, and there is no ...
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Electron Diffraction Pattern (spot in the center)

So in the diffraction pattern of an electron beam (or an electron) in a polycrystaline material we observe rings and a central spot . What's exactly the central spot? Is it not diffracted electrons ...
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Intensity of Single Slit Diffraction

I'm currently trying to derive the intensity pattern for a single slit diffraction. In this website (in Spanish) its said that the amplitude can be given as the length of a line and the original ...
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Diffraction Elastic Constants

I'm currently trying to calculate the diffraction elastic constants for hcp material by the method of Voigt and Reuss, the Voigt method is quite straight forward, but with the Reuss method i have ...
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Interference and diffraction pattern without lens

There is a slight conflict going on in my various physics books regarding the apparatus of Young double slit experiment and single slit diffraction. In some books they have written that a lens must be ...
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Huygens principle and small aperture

Does Huygens principle depend on the ratio of the wavelength and the dimension of the aperture? Do waves extinguish themselves by ratio 10 or more due to interference, e.g. will the wave pass through ...
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Vertical peaks in single slit diffraction pattern

I have the output from a single slit diffraction experiment using a HeNe laser (632.8nm), the diffraction grating is placed vertically so you expect to see only horizontal diffraction peaks in the “...
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Why don't two identical monochromatic lamps form interference patterns?

Monochromatic light of intensity I from two identical lamps is incident on a screen. How will the intensity vary with distance, x, from the center of the screen. From my knowledge of Physics, I would ...
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What is the smallest value of the incident angle in Bragg's law?

The title of my question basically is what I want to know. In Bragg's law, $nλ = 2 d \sin{\theta}$, if we want to find, let's say, $d$, and know only $\lambda$ and $n$, but not $\theta$, what could be ...
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How to demonstrate interference or diffraction in class?

High School physics teacher here. I was wondering about a simple experiment that I can perform in class to demonstrate interference or diffraction. Can you suggest anything? I am not looking to ...
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Mott-Bethe electron scattering factor at g=0

I am a non-physicist, but am doing some calculations related to electron diffraction in (crystalline) solids. Generally, electron scattering factors $f_\text{e}(s)$ can be estimated from the xray ...
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Double-slit interference pattern from double-slit diffraction pattern in the limit of zero slit-width

The intensity pattern of the double-slit experiment should change from the double-slit diffraction pattern $$I=4I_0{\rm sinc}^2\left(\frac{\pi b\sin\theta}{\lambda}\right)\cos^2\left(\frac{\pi(b+d)\...
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A question concerning interference and diffraction [closed]

hi, I have recently been doing this problem and when looking at the mark scheme for d iii it says the secondary maxima intensity decreases however I believe this not to be true. Understanding it to be ...
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Diffraction of a plane wave

Let's consider a plane wave hitting a surface with an aperture of width e in the following fashion: The amplitude of the plane wave is given by: $ a({\bf r})=a_0\exp(i{\mathbf k}\cdot{\mathbf r}) $ ...
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Fresnel's Half Period Zones

When one finds the contribution from half period zones, it turns out to be (m1)/2; where m1 is contribution due to first HPZ. But when reading diffraction due to a straight edge, half of all the HPZ ...
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How is a diffraction sheet made?

This is Action Lab's explanation: "The way these diffractive sheets are made is there’s not actually slits in it like the double slit experiment. There’s lines and grids of reflective surfaces ...
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Why does diffracted light in certain TVs get collimated in six straight or curved rays? [duplicate]

This evening, looking at the television in my apartment, I noticed that the light reflected on it manifested some kind of regular pattern. When the source of light is sufficiently far, this consists ...
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Radiowave diffraction

When a far field propagated radio wave encounters an obstacle such as a mountain does the radio wave actually bend around the mountain? In other words should my receiving antenna on the other side of ...
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Single slit diffraction with a slit width much larger than the wavelength

It is known that for a diffraction pattern to be strong, the wavelength of incoming laser light should be comparable to the slit size. The reason being if the slit is very narrow it effectly is a ...
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How does the polycrystalline structure of graphite produce the circular rings in electron diffraction experiment?

When one performs the electron diffraction experiment to measure the lattice spacing of a polycrystalline graphite one gets the following pattern: My lab manual and other online sources give the ...
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Why does diffraction produce a pattern of light and dark coloured bands? Or, why doesn’t a normal plane/spherical wavefront give a pattern?

I know that diffraction is the changing of a plane wavefront into a spherical wavefront and I understand why it happens (Huygen’s principle), but I don’t get why it gives a pattern of light and dark ...
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Can this wavlength expression be simplified further?

I am supposed to be expressing the wavelength of light that produces 1st order fringe on the viewing screen, given that the diffraction grating has spacing d and the fringes are viewed on a screen ...
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Coherent and incoherent electron diffraction

I am learning about electron diffraction in a transmission electron microscope and was wondering about following topic: A single crystalline material will exhibit a diffraction pattern with discrete ...
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Why is Bragg's Law always presented as $n\lambda=2d\sin \theta$?

In the vast majority of texts and handbooks on Bragg diffraction, Bragg's formula is presented as: $$n\lambda=2d\sin \theta\tag{1}$$ where $\theta$ is the incident angle. But constructive interference ...
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Diffraction order and Ewald sphere

I came across an exercise read as follows: Consider a two-dimensional cubic lattice with a unit length of a=4 Å. Use an appropriately constructed reciprocal lattice and determine the energy of ...
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SAXS vs. X-ray diffraction?

Both small-angle X-ray scattering and X-ray diffraction can be used to obtain structure factors, though I imagine the wave vectors accessible to each are different (?). What are the main differences ...
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What are these stripes in swimming pool light lenses called which make the LEDs seem as if they are pointing towards us, no matter where we are?

What are these stripes in swimming pool light lenses called which make the LEDs seem as if they are pointing towards us, no matter where we are? How do these stripes work? Also, should their angle be ...
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Can the variation of count rate over distance for a disk radioactive source be treated as an electric field of a disk charge problem

So I did an experiment in which the count rate of a disk source of Sr-90 is measured using a plane detector, varied from ~0.7cm to 100cm, multiplying the count rate by the distances squared (i.e. $\...
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Why is the resolution of a tunneling microscope not limited by the wavelength of the electrons?

Why is the resolution of a tunneling microscope not limited by the wavelength of the electrons? Is it impossible for the electrons that are tunneling across the gap to appear somewhere in the gap, ...
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What does a local maximum under 1 in a two-point correlation function mean?

Two-point correlation functions like the radial distribution function (real space) and the structure factor $S(q)$ (reciprocal space) give information about correlations in a (typically) fluid ...
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Is it possible to find out coordinates of slits by interference image?

Is it possible to find out coordinates of slits by interference image? Actually I have several questions. Assume my friend gave me a stripe which shows interference picture of light (like in a ...
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Diffraction pattern for a cosine crystal

I have a 2D square crystal which has a continuous potential $U(\vec r)$. It stretches to infinity. I want to find the diffraction pattern for this crystal. The potential I use is $$U(\vec r )=U(x \hat ...
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Where does the 1.22 come from in Rayleigh criterion for circular apertures?

For the formula 1.22, $\lambda/b$, which describes the angle at which resolution occurs, where does the 1.22 come from? I have looked at the derivation and there doesn't seem to be any explanation?
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What happens in Young's double slit experiment and Fraunhoffer's diffraction actually?

In Fraunhofer's diffraction, is it the interference of light rays of two secondary sources in a wavefront of a primary source? And in Young's double slit experiment, is it the interference of light ...
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Ultrasonic diffraction

When ultrasonic is applied to a liquid it creates an acoustic grating in which some part have more refractive index and some part have low refractive index. When light is passed through this grating ...
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Pinhole diffraction conundrum

I've been playing around with laser diffraction quite a bit lately. Yesterday I tried to have a shot at diffraction of a laser beam with a pinhole. The pinhole was created by slowly penetrating a ...
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About Arago spot and the fringe distance formula

The Arago spot in the center of the shade seams mysterious because it is due to diffraction and in diffraction of a slit the distance between fringes are ruled by the formula $D=л.L/d$ where $л$ is ...
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Assigning Miller indices to Bragg diffraction angles

I am a bit confused with the procedure to index diffraction peaks obtained in X-ray crystallography using the powder method. The incident wavelength $\lambda$ is known and the lattice constant $a$ is ...
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Not getting consistent answers using Lommel functions to calculate Fresnel difraction patterns

I am trying to calculate the difraction pattern at a distance z=50mm behind a circular aperture from an on-axis point light source r0=0.6m in front of the aperture. I am doing this for a variety of ...
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Finding angles of second and third order minima given only angle of first order minimum

For the following problem we are asked to find the second and third order minimums of a single slit diffraction experiment at $13^{\circ}$. I tried using the following $$\theta_p=p\cdot\frac{\lambda}{...
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Why are shadows sharp close to the object, but blurry farther?

There are quite a few questions about blurry shadows and diffraction on this site, though, none of them specifically answer my question about why shadows blurriness is distance dependent, that is, why ...
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Missing order of multislit diffraction

Does multi-slit diffraction have missing orders? If yes, does the calculation is same as $$ a=\left(\frac{p}{m}\right)b $$ where, a = slit interval b= slit width p and m = orders for a and b ...
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Does constructive interference automatically imply bright fringes at all times?

Suppose two waves interfere constructively at some point, in a double slit experiment set-up. This essentially means that the two waves have their peaks and troughs in sync with each other, and there ...
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How one explains the formation of this type of fringe pattern of double slit experiement with wavelength comparable to width?

How can the fringe pattern by two slits which are satisfying the "criteria of wavelength being comparable to slith widths" , show the pattern as depiicted in the last figure in the image ...
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Is energy not conserved in a microscope?

The Point Spread Function (PSF) of an imaging system is its impulse response and defines how a single point on the sample plane is spreaded on the image plane. The simplest model is the one calculated ...
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Determining the structure of a crystal from its diffraction pattern

I am given the Laue interference patterns (in reciprocal space) of two crystal structures, being either simple cubic (sc), body-centered cubic (bcc) or face-centered cubic (fcc), with the task to link ...
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"Loss" around the transmitting window of a laser cavity due to diffraction?

Take a laser cavity consisting of a gain medium, a totally reflecting mirror, and a partially transmitting window: (https://www.researchgate.net/figure/Laser-cavity-composed-of-a-gain-medium-in-...
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In the Young's Double Split Experiment, how does the intensity of fringes vary with distance?

My Physics textbook introduced the topic with considerations of only the interference of the in-phase waves and leaving aside the property of diffraction for the later part. This way it plotted the ...
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