All Questions
28
questions
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votes
1
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47
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Directionality of laser light in vacuum [duplicate]
It is well-known that laser light is directional because of coherence from stimulated emission. This means that the light is emitted ONLY in the direction of propagation, and not in any type of ...
0
votes
0
answers
9
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Does the beam image invert on each round-trip through a hemispherical laser cavity?
When one creates a hemispherical laser cavity, using one flat and one concave mirror, does the beam image invert each time it makes a round trip? I know when passing through the focus of a lens/mirror,...
0
votes
0
answers
48
views
Can lasers really show microbes in water?
I used a 532 nm green laser and passed its beam through a water droplet. Can you explain me are these really microbes and if they are then how a laser is able to do so?
0
votes
0
answers
178
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Maximum Intensity for Gaussian Beam
So I wanted to find out the maximum intensity for a Gaussian beam for a given aperture $D$ which is valid for near and far field, as a function of distance $z$, wavelength $\lambda$ and initial power $...
0
votes
2
answers
164
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How can I collimate a laser beam of 100 wavelengths in vacuum?
Before collimating, the beam will have diverged a bit to a radius of 5cm, the range of the wavelengths is 1400-1600nm and I don't want to lose more than 30% of initial power.
I'm asking in general how ...
- 1
0
votes
0
answers
29
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Generation of an beam with an arbitrary initial profile
Is it possible to generate a beam with an arbitrary initial profile? For example, the finite Airy beam has an initial profile $$\phi(s,0)=exp(\alpha s)Ai(s).$$
In practice, this finite Airy beam is ...
- 21
1
vote
1
answer
353
views
How does the effective focal length work for aspheric lenses? How should I select an aspheric lens?
I am currently looking at aspheric lenses on Thorlabs. I want to use them as a collimation optic for my interferometry experiment. Note that the lenses have a listed EFL (effective focal length). But ...
- 889
2
votes
1
answer
84
views
Frequency "changed" on changing the medium
I have been taught in my school (and read on many internet sites too) that frequency of light doesn't change by changing the medium.
Also I read that the colour we see depends on the energy of the ...
- 8,230
0
votes
1
answer
372
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Why does a shorter-wavelength laser beam diverge less than a longer-wavelength one?
Also, does this phenomenon apply only to lasers, or also to other EM beams?
I wonder if the answer is related to the fact that diffraction limit(s) are proportional to wavelengths...
- 4,509
0
votes
1
answer
253
views
Laser spot size with pinhole
I am currently trying to find the focus of an IR laser beam by using a 300 $\mu$m pinhole. Now, when I am scanning the pinhole across the beam and plotting the pinhole position vs the laser spectrum ...
1
vote
0
answers
81
views
Practical realization of a optical system for a laser
I'm doing a pre-diploma thesis on how to build a laser system for the treatment of carbon nanotubes at my university. I'm relatively far into the whole project, we've already acquired a laser system (...
0
votes
0
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34
views
How Gaussain beam exaclty be after diffraction between two mediums?
How it will be the refraction of the Gaussian beam, does one of its sides will go in distortion, and which equations can predict this distortion?
Sure I have to use Snell's law to know the angle but ...
- 39
0
votes
1
answer
266
views
Finding intensity of laser after round trip in cavity with single mirror [closed]
I came across a question in a text book today, and was wondering if someone could maybe check to see if my physics and workings are correct, as I am getting a intensity value greater the what going ...
- 579
1
vote
1
answer
905
views
How to make light beam to be super narrow?
I am doing a project to use a regular laser beam to be super narrow (25um diameter). I am thinking to use some lens setup to do that. Does any lens setup can make a 5mm diameter laser light source to ...
5
votes
1
answer
2k
views
Beam splitters- Direction of use - again
Can anyone help me understand the effective performance characteristics when sending a beam in to non-entrance faces of a cube beam slitter? (specifically visible non-polarizing ones if it matters)
...
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