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2
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2answers
193 views

Can we observe diffraction even if the slit size is tending to zero?

According to Huygens principle, if we consider any point of the primary wave fronts, each point is the source of secondary disturbance. If the point size we consider tends to zero, the number of ...
3
votes
1answer
1k views

Relationship between slit size and wavelength in diffraction

Almost in every book on physics we can find a statement like "diffraction gets stronger when the size of the slit is comparable to the wavelength". Let's say we have a wall in a bathtub with a slit in ...
3
votes
2answers
485 views

White light diffraction

I have a hard time understanding why light waves of different wavelengths diffract in a different manner. According to Huygens' principle, every point on the wavefront is a source of a secondary wave. ...
3
votes
1answer
138 views

Why is the Fraunhoffer Pattern the Fourier transform of the slit?

Why is it that the fourier tranform of the slit (with value 1 where it's open?) gives the fraunhoffer diffraction pattern? Why are these two paired?
1
vote
2answers
173 views

What is Diffraction?

Diffraction is just light interacting with small objects, and bending, but this seems like a very imprecise definition to me. What is diffraction, actually? I was confused because there are at least ...
1
vote
2answers
310 views

Why do waves diffract?

There have already been a lot of questions on this site on diffraction but I still believe this one might be slightly different. In electromagnetic waves, diffraction and any other phenomenon of wave ...
0
votes
1answer
38 views

Diffraction from interatomic spacing

In diffraction from a single slit, we learn that the angular width of the central maxima, is given by $2\sin^{-1}\frac \lambda d$. For $d\approx \lambda$, the incoming wavefront should be spread to ...
0
votes
0answers
64 views

periodicity of diffraction gratings

Imagine we have a diffraction grating consisting of N slits (being N very large) with a separation of "d" from slit to slit. Now, we could regard this grating as a diffraction grating constructed by ...
0
votes
1answer
94 views

Diffraction of sound

The sound waves, by the virtue of it being a wave, shows diffraction and interference. But in diffraction, I learnt that if the wave is allowed to enter through a small aperture, there is a central ...
1
vote
0answers
76 views

Spreading UV light? Fresnel lenses?

I'm making a little UV exposure box and I'm looking for a way to evenly spread out the UV light. I've used Fresnel lenses to do just this in the past, but that was for visible light. But from what ...
4
votes
3answers
71 views

Why don't fogbows appear on clouds?

As far as I know clouds are lot of small droplets condensed in air. If droplets are large enough we see a rainbow. If they are small we see a fogbow. Although the size of the droplets are big enough ...
3
votes
2answers
185 views

Diffraction by a lens

The fraunhoffer treatment of circular apertures yields a diffraction pattern of circles, with the first minimum (dark ring) at an angular radius of $\theta$ where $\sin(\theta)=1.22\lambda/b$, where ...
0
votes
1answer
147 views

Diffraction/Bragg's law : how does $2\theta$ come about?

I'm trying to get my head around a problem (I should have checked whether I had the answer in class, the exams are coming up now and I don't know if I'll get a lecturer response over the holidays) I ...
2
votes
2answers
706 views

Fresnel distance and Geometrical limit

I read about the geometrical limit of wave theory. The source from where I read had a slightly different explanation to provide than here(The more rigorous answer is too complicated for me to ...
2
votes
1answer
236 views

Diffracton at the edges of an opaque object?

To understand the phenomenon of diffraction as an interference effects of several dipole oscillators (like in case of several symmetrical, not sawtooth, scratches in a diffraction grating), we ...
0
votes
2answers
144 views

How to be sure that a He-Ne laser light is monochromatic

How can I be sure that the emission of a He-Ne laser contains only one single mode of laser cavity? The only thing that I know is that if I use a diffraction grating and the light isn't ...
0
votes
0answers
44 views

What is the importance of the Odderon?

From hep-ph/0001149v1: (1) an Odderon contribution is absolutely necessary to reproduce quantitatively well the data; while its presence is not explicitly needed at $t = 0$, its inclusion is ...
6
votes
1answer
185 views

Is Huygen's Principle Axiomatic?

Is Huygens Principle just a fundamental way to understand light? It always seemed to me that it was somehow "derived" or that it should be-but is it simply a well-founded theory?
2
votes
1answer
169 views

Diffraction at apertures with arbitrary angle to wavefront

Every physics book I know explains diffraction (e.g. at slits, gratings and circular apertures) in a way which assumes that the light wave impinges perpendicularly on the aperture. Would there be any ...
0
votes
1answer
201 views

Matter Waves Interference

When an EM wave diffracts, I can imagine that its EM field interacts with the charges in a certain obstacle thus inducing a wave behaviour on the charges of the matter that will interact with the EM ...
0
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2answers
380 views

Diffraction Grating Spectrometry Question [closed]

Yes, this is a homework question, but I've already failed to solve it enough times that the online system hosting it isn't going to give me any marks, so I figure it's a good time to stop hitting the ...
0
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0answers
30 views

Close to diffraction grating

Being interested in the diffraction of a coherent laser close to the diffraction grating, I find nowhere what the pattern looks like relatively to the distance between a diffraction grating and the ...
0
votes
0answers
82 views

Why do I get different colours in scratched holograms?

I was making a scratched holograms and in result got different colours instead of white hologram
1
vote
2answers
91 views

What happens to the physical properties of electrons after diffraction?

Particle Wave duality shows us that waves and particles are the same thing. Therefore electrons can be viewed as both particles and waves. The wave properties of electrons can be seen in the double ...
0
votes
1answer
149 views

Proof of diffraction equations

If light incident on a grating makes an angle φ with respect to the normal to the grating, show that dsin(θ)=mλ becomes d[sin(θ-φ)+sin(φ)]=mλ. I began by showing: d[sin(θ-φ)+sin(φ)]=mλ, θi=φ=θ at ...
0
votes
1answer
124 views

Diffraction Grating in spectrophotometer

In terms of spectrophotometer, we need to make the light monochromatic before passing it to sample. For that, we use diffraction grating. From the research, I found out that the grating reflects light ...
10
votes
2answers
2k views

Amateur moon laser ranging

Questions first, then my rough estimations: 1) Is it possible to perform moon laser ranging with amateur motorized 114mm telescope? My calculations suggest that for 1mJ laser it should receive ~2 ...
4
votes
3answers
1k views

Why does a CD work as a diffraction grating even with light from a light bulb?

I have a really hard time solving the following problem I accidentally came across today. Looking at the back of a usual CD one sees coloured bands. This is explained by the fact that the surface ...
5
votes
4answers
154 views

Why can't we perfectly focus light-abberations aside

I don't understand why there is necessarily a diffraction limitation on optical systems. Where does this limitation in focusing light come from?
2
votes
3answers
138 views

Law of refraction from Scalar Diffraction Theory

I am trying to figure out if Snell's Law for refraction can be derived from Scalar Diffraction Theory. The setup is this: light (plane wave, with wave vector $\vec k_i = (k_x, k_y, k_z)$ ) falls on ...
2
votes
3answers
596 views

Why is it difficult to differentiate between interference and diffraction?

Why is it difficult to differentiate between interference and diffraction? Is it because we don't clearly understand how both of these phenomenon takes place? My thoughts: From an answer to one of ...
1
vote
0answers
92 views

Do atoms and molecules affect light rays

Molecules of air are all around us all the time. If so, during daylight do rays from the sun diffract as it passes through molecules in the air? and if so is this diffraction negligible to be noticed? ...
4
votes
2answers
111 views

Diffraction pattern when wavelength tends to zero

While studying about Fresnel and Fraunhofer diffraction, I came across a statement which says that the fringes disappears and the image would take on the limiting shape of the aperture when wavelength ...
4
votes
2answers
483 views

Does diffraction occur before interference?

In the double slit experiment, light passes through two slits and the waves interfere and form an interference pattern. A single slit is required for diffraction. So, I was thinking about whether ...
0
votes
0answers
345 views

Simulating the Interference Pattern of Fraunhofer Diffraction by a Single Slit

I'm attempting to simulate the Fraunhofer diffraction pattern due to a single slit. We know that the intensity at an angle $\theta$ is $I(\theta)=I_0 \text{sinc} ^2(\beta)$ where ...
1
vote
1answer
51 views

Thinking Clearly about Fresnel Zone of Short Pulse:

Let's say you have a short pulse of light which expands radially from a lightbulb, and it impinges upon a mirror and reflects towards a photodetector which you have places somewhere above the mirror. ...
1
vote
2answers
223 views

Is the thickness of a sample related to the intensity of x-ray diffraction?

I understand that in general if we're adding more planes of atoms (increasing thickness of sample) then the intensity would increase because we have more constructive interference. But isn't there a ...
3
votes
4answers
5k views

Difference Between Fraunhofer and Fresnel Diffraction

What is the difference between Fraunhofer diffraction and Fresnel diffraction? I mean diffraction is just bending of light waves or waves in general around a point. So how can there be two types of ...
3
votes
1answer
519 views

Fresnel Diffraction at a circular aperture

In Fresnel Diffraction at a circular aperture the central image according to 'Optics' by brij lal and subramanyam will be bright if odd number of full half-period zones can be ...
0
votes
1answer
95 views

Time duration for pulse of single electron viewed as a wave

Electron as an example has a de Broglie wavelength and could diffract. If it has a single wavelength the time extent of the particle's pulse duration would be infinite .. If it carries a broadband ...
1
vote
1answer
186 views

How does the uncertainty principle make a photon beam spread out?

I'm reading about uncertainty principle, and something has been bothering me for quite a while. There is the formula: $$\sigma_x \sigma_p \ge \frac{\hbar}{2}$$ I know what this means: the more you ...
2
votes
0answers
41 views

Airy Pattern as infinite sum of Fraunhoffer Patterns

Is there a way to view the Airy Pattern as an infinite sum of Fraunhoffer diffraction patterns? I don't know where the 1.22 would come from then. Is there something inherently wrong with collapsing ...
3
votes
1answer
196 views

computing wavefront deviations for off-axis mirrors

Suppose you have two off-axis aligned mirrors which are nearly planar, with small deformations such that a wavefront at plane $P_I$ at distance $-D$ from the mirrors, is refocused at distance $D$ at ...
1
vote
0answers
80 views

What are some problems with Hugyen's wave model of light? [closed]

In terms of the different light phenomenon (reflection, diffraction, rectilinear propagation and dispersion), what are some problems with Huygen's wave model of light?
1
vote
2answers
283 views

Why are diffraction gratings not called interference gratings?

It seems to me that diffraction gratings are completely described by the double slit experiment-why then is it called a diffraction grating?
0
votes
2answers
73 views

Brewster angle with diffraction propagation?

Diffraction theory is scalar. How you deal with beam propagation in fourier optics that is sensitive to the to the polarization? If I have linearly polarized gaussian beam incident on glass surface, ...
5
votes
2answers
384 views

Why does light diffract only through slits?

We can see diffraction of light if we allow light to pass through a slit, but why doesn't diffraction occur if we obstruct light using some other object, say a block? Why are shadows formed? Why ...
0
votes
1answer
83 views

If I take an XRD image of a single cubic unit cell, would the diffraction pattern simply be its reciprocal lattice?

I've seen the rings from powder diffraction images, and I read that each line is made up of a lot of dots, I was wondering if these dots are reciprocal lattice points of the structure. And if we ...
4
votes
1answer
95 views

Is diffraction through an aperture similar to diffraction by a plane of atoms?

I'm asking because I have a problem asking me what the diffraction pattern would be if instead of spherical atoms I'd have triangular atoms. I can't find anything about this in my X-ray diffraction ...
1
vote
0answers
80 views

C Method for Diffraction grating

Alright, so I am trying to find the efficiencies of a coated diffraction grating through the method in this paper. This is through a change of coordinate system. So I went through and derived all of ...