# 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 ...
1 vote
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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 ...
1 vote
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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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### 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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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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