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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Fraunhofer Diffraction - Multiple Square Apertures

I'm stuck for some days trying to get the diffraction pattern from a binary grating / square period grating / multi-aperture square screen... whatever you want to call it. Imagine I have a 8 * 5 ...
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Optical signal/noise effects while driving

When I was driving I made an observation depending on two conditions Condition 1: If my eyes are in sunlight but just in front of me there is shade of trees or anything else Condition 2: There is dust ...
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How to understand Bragg rods?

From reading this PRL, I came across the idea of the reciprocal lattice of crystals being spread out in diffraction to "Bragg rods". Is there a good intuitive explanation of this? I'm ...
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Diffraction due to a long slit

I know the equation of net electric field at any point from a rectangular aperture in Fraunhofer diffraction. But I have come to know that if the length of the slit is finite than there is no ...
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Young slit conundrum - Finding positions of maxima when one of the slits emanates light with phase difference

Second guessing myself a bit here, but I've run into a bit of an issue. The problem I'm trying to solve is this: Coherent light of $532nm$ is passing through a double slit, which are separated by $25\...
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Intensity of a grating pattern in the limit of infinite slits

$$I\propto \frac{\sin^2(N\delta)}{\sin^2(\delta)}$$ Where $N$ is the number of slits and $\delta$ contains the angle, wavelength and slit spacing dependence. In the limit as $\delta \to 0, I \to N^2$. ...
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Diffraction & Width of slit

I was told that diffraction through a slit occurs as follows- When the 'point sources' of the planar wavefront at the location of the slit emit secondary wavelets we find bright and dark spots at ...
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X-Ray Diffraction: Calculate the phase difference at the detector between waves scattered by 2 different points in a sample

I have very little idea what I'm doing here, but my goal is to calculate the difference in phase of the waves scattered by 2 points in some sample. The figure below shows my interpretation of the ...
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Fourier Optics: Far Field Image

I have a question about computing the far field diffraction pattern of a laser beam: If $L_{1}$ is large enough, then at $z=L_{1}$ we see the Fourier transform of the input $f(x, y)$. If $L_{2}$ is ...
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Single Slit Diffraction : Problem with the condition of diffraction

The condition for diffraction is that the effects of diffraction become more noticeable when the width of aperture is comparable to the wavelength, and from that we can say the spacing of fringes ...
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Diffraction By Small Holes - Hans Bethe 1944 paper

I am a beginner physics student and my background is not in mathematics so I have an elementary question - I am trying to follow along Hans Bethe's 1994 paper on the diffraction of electromagnetic ...
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$\rm Lux$ to $\rm W/m^2$ conversion?

For a physics project, I'm planning to investigate the relationship between the number of slits in a diffraction grating and the intensity of the central maxima. The light meter which I'm planning to ...
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Why doesn't the acousto-optic frequency shift depend solely on the velocity of sound in the medium, if it is a form of Doppler shift?

Many optics books make the statement that the frequency shift of a laser beam from the acousto-optic effect can be thought of as a Doppler shift from a traveling index of refraction grating (pressure ...
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Diffraction due to a long narrow slit

I wanted to derive an expression for intensity due to a single slit whose dimensions are 1m and a ( where a is of the order of wavelength (diffraction. For that firstly I divided the slit into ...
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Diffraction of light (slit)

According to some books, diffraction occurs when there is an obstacle whose linear dimensions are comparable to the wavelength of light. This is true also for a hole or a slit through which the light ...
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Why do waves, specifically light, diffract through a slit?

I've been wondering this for a while now, and have thus far only come across answers that seem to use an equation as an explanation. I've also looked at Huygens' principle (albeit not in-depth), but ...
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Why is resolution half the wavelength?

My biology textbook says: The general rule is that the limit of resolution is about one half the wavelength of the radiation used to view the specimen. This means anything smaller than half the ...
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The maximum wavelength obtainable from a diffraction grating

I am trying to understand what exactly is meant by the following question: What is the maximum wavelength that can be obtained with a given diffraction grating in (a) the first order (b) the second ...
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How do Airy disks happen in focused vs unfocused light?

In articles about Airy disks, I can't find whether they are talking about an aperture with a lens or mirror that focuses the light, or about a plain aperture. Most of the time they are talking about ...
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Diffraction from fcc(111) surface

Take the (111) surface of a fcc lattice: If we have a wave incident on the surface moving in a direction with a projection parallel to the orange line, then in principle we should observe diffraction ...
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Is there an analytic expression for the Fresnel pattern from a circular aperture?

I am interested in the Fresnel diffraction pattern (over an entire observation plane, not just the value on-axis) due to a plane wave incident on both square and circular apertures. I have two optics ...
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Classical derivation of first and second minima in Single slit diffraction

I was reading about single slit diffraction in Fundamentals of Physics by Halliday and Resnick. So, to derive the equation for first minima, they divided the slit into two halves. If the width of the ...
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Xray diffraction [closed]

why to diffraction, the spacing between the scatterers and the wavelength should be similar in size, For example in xray diffraction to determine crystal structure? If it not similar what does happen?
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How large is the reflected pattern on the Earth by a retroreflector array on the Moon illuminated by a laser on Earth?

I've been thinking about What is the minimal equipment required to observe the Apollo lunar retroreflectors? for a while and every time I start to estimate the strength of the received signal I choke ...
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Why does a rainbow pattern appear, in a picture I took with my mobile in the mirror with flash?

I took a picture in the mirror with a flash (and in a flash). This was the result: After a comment made below by @SuperfastJellyfish (indeed widening occurs), I made another picture (this time in the ...
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Elastic scattering violates energy conservation?

In our introductory solid state lectures, the professor described von Laue's$^1$ diffraction conditions making the assumption of elastic scattering, which states that the incoming and the scattered ...
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Steps to calculate the near-field diffraction pattern after an aperture (for distances so close that the Fresnel regime is not valid)?

This question has arisen out of a previous question regarding the various approximations in optical diffraction theory, and when they can each be applied. I would like to know the steps that must be ...
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Does Fraunhofer diffraction also automatically imply that the Fresnel approximation is simultaneously satisfied?

I am confused about the regimes of validity for the Fresnel and Fraunhofer diffraction approximations, and would appreciate some clarification. Let's say we are interested in calculating the field $...
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What is the geometric derivation of 2D Fraunhofer aperture diffraction?

In this derivation, I can understand the formulas stated for 1D diffraction for both x andy (with the phase difference $\delta= ksin\theta y$) in the far-field limit, but how can we just sum the ...
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Is there always a maximum at the centre of a single slit diffraction pattern?

The common derivation of a single slit diffraction pattern uses the far field limit which of course will imply a central peak in the diffraction pattern (since we assume the slit is much thinner than ...
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Spatial Light Modulator (SLM) phase-only versus amplitude-only modulation

I am reading about the phase-only vs amplitude-only modulation with Spatial Light Modulators (SLMs). I wonder if there are specialists here who do this for living. For instance, here the authors ...
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Why do I obtain the wrong total power when integrating this Fraunhofer diffraction irradiance pattern for a circular aperture?

I am looking for some help understanding something. I am working through my optics textbook (Hecht, 4th Edition), and am following the example of the far-field Fraunhofer diffraction pattern caused by ...
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Why is an opaque edge or a slit necessary for diffraction?

The Huygens–Fresnel principle states that every point on a wavefront is itself the source of spherical wavelets, and the secondary wavelets emanating from different points mutually interfere.The sum ...
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Why is the diffraction pattern like the interference pattern as opposed to a smooth band?

Why are diffraction patterns similar to interference patterns? I understand interference patterns but I can't wrap my head around as to why the diffraction pattern would be similar? Does diffraction ...
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Single slit diffraction momentum of particle

I was studying single slit diffraction theory from a book which said and i quote "we may assume the light source to be sufficiently far away from the slit that the photons approaching the slit ...
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Why is Bragg diffraction small-angle for thicker layers and/or larger molecules or unit cells? And wide-angle for small or shallow crystals?

It is easy to find equations that quantify this on the internet, but not an explanation as to why... Also, does this apply to electrons and neutrons? Or just X-ray reflection/diffraction?
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Kinematic theory and dynamical theory of x-ray (or electron) diffraction. Why such names are given?

Kinematic theory and dynamical theory of x-ray (or electron) diffraction. Why such names are given to scattering theories ? Does it have any connection to Kinematics (of Galileo) and Dynamics (of ...
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Huygen's Principle in Single Slit Diffraction: The Contribution of Each Wavelet

The question I am trying to answer is as follows: "Let $y'$ represent the position of a point within the slit $a$ in Fig. 36.5a, with $y' = 0 $ at the centre of the slit so that the slit extends ...
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Diffraction of sound waves vs EM waves

How does the diffraction of sound waves differ from the diffraction of EM waves? EM waves have their electric field vector point in a direction perpendicular to the direction of travel and sound waves ...
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What makes diffraction spikes move with the focus?

This is a bit of a follow up on The Bahtinov focusing mask and it came with this question on Astronomy. But I think the effect can also be observed when looking through a hazy atmosphere or a stained ...
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Validity of Fresnel Approximation

This is in relation to the scalar diffraction theory described in the Introduction to Fourier Optics by J. Goodman. A sufficient condition for Fresnel approximation to be valid is that the higher-...
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Would there be any changes in polarisation for light that is diffracted by diffraction gratings?

My understanding is that s and p polarisation of light will have a different angle when diffracted by diffraction gratings. In wikipedia it says that "According to the Huygens–Fresnel principle, ...
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X-Ray Diffraction pattern peak tailing

I have recently been working with Rietiveld refinement on powder X-Ray Diffraction (XRD) patterns by using the GSAS2 (General Structure Analysis System) program where, one of the steps, is to produce ...
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Factor 0.62 in near field distance formula (reactive to radiative)

Short version: Please derive the 0.62 in the formula for the distance of the transition between reactive near field and radiative near field $0.62\sqrt{D^3/\lambda}$. Long version: I regularly work in ...
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Treatment of “thickness” of medium for light traveling through a low-index medium and being reflected from the surface of a high-index medium

I am currently studying the textbook Modern optical engineering, fourth edition, by Warren Smith. Section 1.5 Interference and Diffraction says the following: Now if the waves arrive at C in phase, ...
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Derivation of intensity at the central point in single slit diffraction

The legend himself, John Rennie, spent several hours in chat to convince me that if the slit width in a single slit diffraction pattern is doubled, then the intensity at the central point becomes $4$ ...
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Fourier transform of a Bessel function multiplied by a Gaussian

I am computing the diffraction pattern of some specific grating. I end up with the following integral $$I = \int dx\, J_m(x)e^{-ax^2}e^{-ikx}$$ which is the Fourier transform of the Bessel function of ...
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If the number of cycles is the same, or differs by an integral number of cycles, then the two beams of light will arrive at the same phase

I am currently studying the textbook Modern optical engineering, fourth edition, by Warren Smith. Section 1.5 Interference and Diffraction says the following: Now if the waves arrive at C in phase, ...
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Is diffraction empirically derived or based off something else?

after reading about diffraction I am confused on how its effect came to be understood. Can one derive diffraction from the wave equation and base principles or is it a result of empirical observations?...
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Is proton diffraction more difficult to obtain experimentally?

I was studying the phenomena of particle diffraction and saw that any particle can be associated to a de Broglie wavelength, given by $$λ=\dfrac{h}{p}$$ Experimentally, we commonly talk about the ...

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