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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Diffraction and the treatment of Complex conjugate in a summation function

I understand that for the wave function ($\Psi$(r)), |$\Psi$(r)|$^2$ = $\Psi$*(r)$\Psi$(r) and that in exponential form this is: |$\Psi$(r)|$^2$ = A*e$^{-ik.r}$Ae$^{ik.r}$ which leads to the result: ...
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Diffraction pattern and grating using mesh and Telescope

I recently attended a demonstration at an observatory when a undergraduate Astronomy student showed me something neat. A telescope was pointed at a star. The student then waived a window covering with ...
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How can the waves interfere in X-ray diffraction?

This is the popular diagram surrounding the Bragg's law for X ray diffraction: But what I seem to not be able to understand is when they say that the reflected waves interact constructively to create ...
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How can the intensity of the center of Arago's spot be calculated?

I am currently working on measuring the relationship between the diameter of the sphere and the intensity of the center bright point of the shadow with Arago's spot. I have been researching with ...
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Does the manipulation of the Fresnel number and light intensity work?

I am currently a high schooler and am trying to find the intensity of the bright point in Arago's spot. I am trying to find some manipulation of equations to hopefully gather the intensity of the ...
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Why do diffraction limits exist?

My question does not deal with standard derivations of diffraction. I have no doubt that I can follow standard derivations for diffraction phenomena. Actually, I have probably been shown these before, ...
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What happens if you put a converging lens in front of a diffraction grating?

I mean a situation like this: Thinking about the intensity function and maxima and minima, I don't really understand the use of a converging lens and what a difference focal distance does to the ...
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Can someone explain the Fresnal diffraction simply? [closed]

I have been researching and found multiple equations. There are ones for the Arago's spot, fresnel number, fresnel diffraction, fresnel integral. They often lead to other wave behaviors which confuses ...
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What unit should I use to measure the light intensity of aragos spot

I am trying to measure the relationship with the radius and its effect on the light intensity of Arago's spot. I plan to use a camera or a light meter but I am not sure what unit to use in my ...
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What causes light passing through a hole to change direction?

On diagrams showing light passing through a hole, the wave of light appears to change direction when it emerges from the hole. What causes that change of direction? Is it maybe the walls of the hole ...
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What is the path rays in Fabry–Pérot interferometer for calculation it resolution?

A Fabry-Perot interferometer shown in Figure below essentially consists of two parallel plates of glass whose inner surfaces are polished to a very high degree of flatness, and then coated with a ...
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Effect of different aspects of spacing in a grating

I am trying to conceptually understand the effects of different aspects of spacing in scattering and am having trouble with it. Could someone provide some insight? Imagine we have the above scenario (...
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A doubt about Kirchhoff's scalar diffraction theory

Scalar diffraction theory assumes a scalar wave equation of the form $$\frac{1}{c^2}\frac{\partial^2u}{\partial t^2}=\nabla^2u$$ where $u(\vec{r},t)$ is a scalar field called the optical disturbance. ...
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Why do we need a double slit experiment, when a single slit experiment shows that an electron/photon behaves like a wave? [duplicate]

To demonstrate wave-particle duality, it is often stated that we need to perform a double slit experiment. However, it seems that in a single slit experiment, individual photons or electrons behave ...
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Can anyone refer me to a textbook or paper that explains the $k$-space diagrams used in Fourier optics to describe diffraction?

I am taking a course in Fourier Optics. Often, we work with these $k$-space diagrams, similar to the one shown in the image below. But we use them without understanding the mathematical justification ...
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Do neutrons change their wavelengths when diffracted?

Both neutrons and X-rays are used in diffraction. In XRD, the diffracted beam is of the same wavelength of the incident beam. The reason is that X-rays are EM waves which cause electrons to vibrate. ...
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Doesn't particle diffraction prove that electron beams show wave-like properties, not a single electron?

I'm reading the experiment for the diffraction of an electron on double-slits and this section of my textbook confuses me. the diffraction pattern isn't shown by a single electron its shown by ...
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How much is the UV index reduced when under the shade approximately?

Assuming simple conditions e.g. sunny, bright day (no clouds), sun is directly overhead, what becomes the effective UV index for someone who is outdoors under solid shade (e.g. sitting under a ...
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How to calculate resolution of pinhole camera?

I am 60 years old. I'm not a student and this is not homework (despite somebody trying to close it as a "homework question".) I'm interested in building a long-focal-length pinhole camera (...
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Why Airy disk (Fraunhofer diffraction) is first order of the Bessel function of the first kind?

I have been studying Fourier ptychography. I am confused about why Airy disk is J1 of the Bessel function. I think that Fraunhofer diffraction looks more like J0 of the Bessel function.
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How To Think About Sharp Shadows In Terms Of Diffraction

I tried to implement difraction as explained here. I used the formula on page 4, right before the simplification to the Rayleigh-Sommerfeld diffraction formula, $$u(x_0)=\frac{1}{4\pi}\int_A u(x)\...
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Connection between Abel transform and Optical Diffraction

Abel transform can be used to extract density of object in 3D from a 2D projection of it on a screen. For example Optical diffraction from an object can yield exactly the same information. For example,...
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Interference or diffraction? [duplicate]

Suppose I have $N$ slits separated by a distance $a$. We are sending a light source of wavelength comparable to the slit width. Then which of the effect should dominate: Interference or diffraction? ...
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Why space telescopes images show diffraction spikes around stars, but not galaxies?

I've seen this tweet recently: https://twitter.com/ThePlanetaryGuy/status/1544801752893067265 Additionally to the image, where it's pretty clear, the post says: Stars are six-pointed; everything else ...
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Refractive Index of a Aspheric lens

I have the following specifications of an aspheric lens: AL5040-B - Ø50 mm S-LAH64, f = 40 mm, NA = 0.54, ARC: 650-1050 nm Is there a way to calculate or identify the refractive index of the lens ...
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Diffraction pattern not on focal plane

In recent lab course we examined diffraction of light. We used a laser with $\lambda=510$nm. The light passed the diffraction grating then was mapped by a lens (distance grating- lens=$2f$) onto the ...
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What is the principle behind diffraction?

If we shine a green laser on a wall in a dark environment, we would observe a bright dot in the middle. Now, if we fix a grating just in front of where the laser is held, when the beam strikes the ...
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Diffraction of photons exhibiting random walking motion

The explanation for the time it takes light to reach the surface of the sun is that photons take a very long random walk through the body of the sun until they emerge ay the surface 1000s of years ...
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Intensity of Diffraction and inteferance

Why intensity of bands in diffraction decrease while moving away from central max while that of interference do not?
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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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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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