All Questions
Tagged with optics diffraction
515
questions
511
votes
6
answers
81k
views
How does light bend around my finger tip?
When I close one eye and put the tip of my finger near my open eye, it seems as if the light from the background image bends around my finger slightly, warping the image near the edges of my blurry ...
- 4,869
35
votes
7
answers
253k
views
What is the difference between diffraction and interference of light?
I know these two phenomena but I want to know a little deep explanation. What type of fringes are obtained in these phenomena?
33
votes
3
answers
3k
views
How is momentum conserved in diffraction?
Sigh. Approaching retirement age and still deeply confused about something I first encountered in highschool 40 years ago.
Consider the usual double slit experiment. Make the light source be a laser ...
- 1,145
31
votes
3
answers
10k
views
Why does light reflected from an LED TV screen make a sharp X pattern?
If you shine a laser pointer or generally any coherent light at the screen of a fancy, new TV, you get a very sharp X pattern.
I think this is a property of LED screens specifically. This phenomenon ...
- 103k
24
votes
3
answers
19k
views
Why do I see three 'beams' when I look to a distant light source at dark?
In the night, when I look at a distant light source (for example a street lamp a few hundred meters away) I do not simply see a spot but rather a spot which is surrounded by 'light beams'.
So instead ...
- 399
24
votes
3
answers
20k
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Squinting at street lights
Simple question, I've always wanted to know the answer to this.
Why do you see a pair of lines radiating out from street lights when you squint at them? I can't think of a better way to describe what ...
user5335
22
votes
2
answers
1k
views
Optimal telescope size?
Consider a diffraction-limited telescope with unobstructed aperture $D$. Such a scope is capable of yielding an angular resolution $\alpha$ that scales as $\lambda/D$, with $\lambda$ denoting the ...
- 19.1k
21
votes
2
answers
5k
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Amateur moon laser ranging
Questions first, then my rough estimations:
Is it possible to perform moon laser ranging with amateur motorized 114 mm telescope? My calculations suggest that for 1 mJ laser it should receive ~2 ...
- 2,424
19
votes
4
answers
79k
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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 ...
- 1,578
18
votes
2
answers
12k
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Why do we see a rainbow of colors reflected off a CD or DVD?
So, we all know if you shine some light on CD (compact disc) or DVD, you can see all the colors from red to violet.
What is bothering me is what is the reason of why do we see the colors on compact ...
- 327
16
votes
4
answers
3k
views
Reverse of diffraction
Can we arrange a practical in such a way that the dark and bright bands in diffraction grating be allowed to pass through the same slit to get the original light (i.e the incident light before ...
14
votes
8
answers
13k
views
Why does a wave actually diffract?
I know that waves diffract around a slit and this is due to the Huygens-Fresnel principle. But I never understand this in an intuitive wave that why does a wave become a spherical wave front at the ...
- 2,479
14
votes
5
answers
2k
views
Technical explanation of "Hitachi lensless camera"
Hitachi is bragging about a thin lensless camera. I can't find any technical information on how it works---just press releases etc.† Can anyone work backwards from the published descriptions to ...
- 16.7k
13
votes
2
answers
183
views
DIY Spectrophotometer doesn't work properly in the IR range
I've built an optical spectrometer by following the instruction given on the Theremino website: Theremino_Spectrometer_Construction.pdf, but I'm having a little issue with it.
Everything works ...
- 321
13
votes
2
answers
495
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Why do diffractions spikes from small aperture not have fringes?
Small aperture in a photo camera leads to well-known starburst effect:
(source)
It's generally believed to be caused by diffraction.
But since diffraction is a wavelength-dependent phenomenon, it ...
- 29.1k