# 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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### 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, ...
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 ...