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18 views

Diffraction of light around an object & human perception

A wave exhibits diffraction when it encounters an obstacle that bends the wave or when it spreads after emerging from an opening. Diffraction effects are more pronounced when the size of the ...
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1answer
43 views

How to transmit light ideally through not parallel tiny holes within a metal case?

I currently try to transmit light through a tiny hole of one side of a metal case in order to receive the light on the other side of the case. The tiny holes are not parallel (see image 2). Using ...
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2answers
23 views

Refraction, diffraction or reflection of human voice

Why is possible to hear in an open space someone's voice even if he's not facing me? Is it because of refraction, diffraction or reflection of the sound wave?
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2answers
56 views

How is the virtual image reconstructed from a hologram?

To make a hologram a film is exposed to an incident plane wave and wave from the object to record the interference pattern on the film. The principle is commonly explained in a way like that in p.1212 ...
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2answers
44 views

Why array of telescope is used?

To increase the resolution of an instrument, smaller wavelength and larger aperture is desirable. It is mentioned in some textbooks that the "effective" diameter of a telescope can be increased by ...
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2answers
35 views

x-ray diffraction of crystals

In explaining x-ray diffraction of crystals, usually the approach is to consider the atoms absorb radiation and scatter it, at some angles constructive interference occur and bright spots can be ...
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0answers
17 views

Question about dark fringe in diffraction

In finding the angle for the mth dark fringe of single slit diffraction using Huygen's principle, they usually split the slit into equal portions. For example, to find the first dark fringe the slit ...
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0answers
27 views

How to measure the diameter of a Glass tube? [closed]

I'm working on something and I need to find the diameter of a glass tube. I wanted to use diffraction pattern to find the diameter of my tube. but the problem is that my tube is transparent. Anybody ...
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2answers
32 views

Slit width in single-slit diffraction

In Born's Atomic physics, he makes the comment on the single slit diffraction that For diffraction patterns to show themselves, it is necessary that the width of the slit employed should be of ...
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0answers
27 views

How to design a grating coupler to produce surface plasmon-polaritons (SPPs) at a desired frequency?

Following on from this question, which I found very useful on the topic, I was wondering how you would use the equation $\beta = k sin \theta \pm \nu g$ to fabricate a grating coupler to generate SPPs ...
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3answers
49 views

Why does sound wave suffer more diffraction than light waves generally?

Why do sound waves suffer more diffraction than light waves generally ? I would like more of a logical explanation rather than mathematical .
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1answer
30 views

Bragg's interference

This may be a little of a stupid question. But I was looking at a diagram describing Bragg's Law of Diffraction. and I was like...how can an interference happen if wave beam C and wave beam C' are ...
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0answers
37 views

Is the human eye diffraction limited, or is there another limiting factor?

I know that most problems involving the human eye in my undergrad physics text book tell the student to treat the human eye as a diffraction limited system (ie to assume the only factor limiting human ...
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20 views

Single slit diffraction treated as a differential equation

I want to find the values of electromagnetic fields that result from single slit diffraction. This should be possible by solving maxwell's equations for appropriate boundary conditions. But I'm not ...
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0answers
19 views

Deviation on the Diffraction Pattern when not perpendicular

Due to Babinet principle, Diffraction pattern of an opaque .... ( you all know ). here my opaque is my wire. So, I know that if I change the angle between beam and wire ( I mean if I don't aim the ...
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0answers
42 views

What is the electric field of a diffraction grating?

I'm trying to follow the equations in "Introduction to Modern Optics" by Fowles. He starts out with equation for a single slit of length $L$ and width $b$: $ U_p = C \int \int e^{ikr} dA $ where $U$ ...
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1answer
37 views

Image formation or Diffraction?

I was watching this video on the YouTube channel Veritasium. In this episode, the host shows people paper containing holes of different shapes in the middle. So there is a paper which has a hole in ...
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1answer
25 views

Diffraction Pattern when not perpendicular

In single slit diffraction, we always assume that our waves are perpendicularly aimed towards the slit. But what if we aimed our waves with different angles ( for example 60 deg)? If we send the ...
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1answer
64 views

Diffraction pattern without a slit

A few weeks ago, I aimed a laser at a wire perpendicular and interestingly, I saw the diffraction pattern, like the picture below: Why is this happening? I mean, I don't have any slits and I'm ...
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1answer
92 views

X-ray diffraction on thin film

As far as I am concerned, when we perform an X-ray diffraction experiment using a Bragg-Brentano diffractometer using the "powder method" we have that the scattering pattern depends on only one angle ...
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2answers
88 views

Huygen's principle and why can't we see atoms with light

First of all, I'd like to discuss Huygen's principle. In order to explain waves diffraction, it says that every point in a wave front behaves as a source, so the next wave front is the sum of all ...
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1answer
100 views

What is a wavelength of an EM wave physically?

This might be a silly question given I am a physics undergrad, but I was suddenly confused. Usually when EM hit a gap they diffract through the gap. But if the gap is too small, diffraction can't take ...
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1answer
39 views

Is crystal diffraction actually diffraction?

It seems like a very common model that is taught in schools for crystal diffraction is that there is an incident plane wave of light on a crystal lattice, and each atom in the lattice scatters the ...
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8answers
578 views

How to measure the diameter of a thin wire? [closed]

I'm working on a project and I need to measure the diameter of a thin bare copper wire but I don't know how. Can you please tell me a way to measure the diameter of a wire? Can you give me a way, ...
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0answers
83 views

How are lattice parameters determined from reciprocal space maps?

It seems that the papers speak of reciprocal space maps with very high praise because of its ability to study strain in epitaxial films and determine the amount of relaxation. Also one can determine ...
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0answers
41 views

What causes this pattern in the reflection of a laser on a screen? [duplicate]

When I shine a red laser behind me at a wall I see a strange reflection occurring on my laptop screen Why does this happen? The pattern on my screen occurs exactly where the laser is hitting the wall. ...
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2answers
82 views

Momentum change of a photon upon diffraction at a grating

How is the momentum change of a photon is related to the grating periodicity and diffraction order? I came across with this question while studying surface plasmon polaritons (SPPs) and how to excite ...
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2answers
57 views

Why light comes out in spherical form after passing through a slit (diffraction)?

I want to know why light comes out in spherical form when it passes through the slit? I know this is due to diffraction but how? And my second question, if there is no difference between ...
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1answer
61 views

Why water wave won't diffract or bend around a boat having a length longer than its wavelength?

I get the slit version of diffraction, with the Huygen's principle. But I don't find the same principle useful. I keep thinking that a obstacle like a boat is the same as two large slits on both ...
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3answers
124 views

Diffraction of matter waves

By considering the De Broglie wavelength of particles, we discover that matter can diffract if passed through openings with itself. This poses a variety of questions, namely Can matter waves ...
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0answers
41 views

Disadvantages of viewing a diffraction grating at larger order?

If you are using a diffraction grating as a spectrometer you are likely to use high order, because you have a better resolution (as a result of larger dispersion??). But are there any disadvantage? I ...
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1answer
79 views

Are we working in the double slit argumentation with destructive interference arguments?

Stimulating water with two long straight bars one could produce linear waves. Having the right distance between the bars and the correct frequency of the steady system we get in the middle between the ...
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0answers
48 views

Relativity - Diffraction Of Light

Following thought experiment. Inside a rocket, right in the middle, we place two lasers pointing in opposite directions. Both emitting the same wavelength. The Left wall of the rocket is L1 while ...
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0answers
96 views

I have negative slop of Williamson-Hall plot, XRD data. Is this right?

I have Ag (silver) powder sample. I measured xdd of the sample and got very good 2theta peak. Since I want to know bulk modulus and Young's modulus of Ag(silver), So, I got williamson-Hall plot ...
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0answers
29 views

How to estimate the lattice parameter from a Debye-Scherrer diffractogram

The question is: In a Debye-Scherrer diffractogram, centers of maximum intensity were noted at the following angles with respect to the straight through position (all these angles are in degrees): ...
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0answers
5 views

How report that bragg reflection from PVC filters is greater than polypropylene filters?

I have been told that PVC filters will give a higher background in XRD analysis due to the high absorption of the Cl component. My argument is that another filter material should be used when ...
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0answers
54 views

Fringe Localisation

How am I to understand where the fringes of a given setup are localised? For example, Young's double slits have non-localised fringes, that is the fringes are localised (and so are well formed) at ...
0
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1answer
31 views

Criterion for resolvability and spot size for optical systems

Look at the following table: By spot size I mean if we have a point source for the object, the angular radius of the spot created by the source as viewed in the image plane. My question is is all ...
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1answer
50 views

Fraunhofer Diffraction and Lenses

Suppose we have the diffraction pattern for a single slit in the Fraunhofer approximation. In order to see this diffraction patter at finite distance we locate a converging lens. Is the diffraction ...
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1answer
40 views

Path length requirement for diffraction problem [closed]

The following question has been asked in a problem sheet I have been asked to answer: "The above diagram relates to the path lengths of radiation, with an angle of incidence, θ, reflecting off ...
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1answer
53 views

Why subwavelength objects can not be seen with optical microscope?

What would happen if we would take a very small sphere around 200nm diameter and try to detect it from the most efficient optical microscope? Technically, the Rayleigh diffraction limit prevents the ...
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0answers
37 views

Trying to understand electron diffraction

I'm trying to understand how electron diffraction works, but I'm not really getting it. Here's an image Here are a couple of questions about it that I can't figure out. Why is the angle of the ...
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0answers
26 views

Does the Abbe limit hold for a single lens?

Let us say I have a single (converging lens) could I use the Abbe diffraction limit (for a microscope) to find its resolution or do I have to use the Rayleigh criterion. (i.e. Is the Abbe diffraction ...
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0answers
45 views

Beating the Diffraction Limit with NSOM

I am trying to understand exactly why we can beat the diffraction limit when using near-field scanning optical microscopy (NSOM). For those who aren't familiar with NSOM, check out this article: ...
2
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1answer
79 views

Do off axis sources produces the same diffraction pattern as on axis sources?

Let's say I have a simple lens and I am viewing two sources of light A and B through this lens. A is on the axis and B is not as shown in the digram below. Will A and B produce exactly the same ...
3
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1answer
529 views

Resolving power of a diffraction grating?

I was working thru a derivation of the resolving power of a diffraction grating at the $n$th order. Here is that derivation: Let us say we have a diffraction grating width $W$ and are looking at ...
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4answers
381 views

Can only one electron or photon produce interference pattern?

If we shoot one electron or photon at a time to a double slit for a long time, interference pattern will build up on the other side. If the gap between each electron or photon is long enough that they ...
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2answers
114 views

How can shadows ever be sharp?

When I hold my hand underneath my lamp, the shadow my hand casts is crisp and sharp, meaning that the edges are well defined and not blurred. But according to Huygen's principle, shouldn't the light ...
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0answers
20 views

Diffraction from a single slit experiment and Heisenberg's uncertainty principle [duplicate]

Practically how to separated between Fraunhofer and Fresnel diffraction? Do all diffraction fringes from single slit have same peaks? Why?
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2answers
56 views

Intuitive picture of diffraction without fictitious secondary wavelet

This question has been asked in a similar way but no satisfactory answers came up. Huygen's principle relies on the fact that if we consider an aperture, every element dS on the surface of the ...