All Questions
Tagged with electromagnetic-radiation laser
118
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33
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Are 'Terahertz-pulse lasers', like, 'Terahertz time-domain spectroscopy' and such, of Terahertz-frequency or trillion-pulses-per-second?
From Phys.org:
Light-controlled Higgs modes found in superconductors; potential sensor, computing uses.
The mode can be accessed and controlled by laser light flashing on the superconductor at ...
- 4,509
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1
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75
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Are Field Beams Possible?
I was recently wondering why the field force between two objects is proportional to the square root of the distance (sometime you just take things for granted). This comes from the inverse-square law, ...
- 1
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2
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43
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Area of detectable optical transmission as a function of distance in the context of SETI
The relevant page on SETI's official website states:
The SETI Institute, along with scientists from the University of California's Lick Observatory, UC Santa Cruz, and UC Berkeley has coupled the ...
- 545
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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
-2
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1
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190
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How to hide radio communications between airplanes? [closed]
I have 2 airplanes and I would like completely hide the communications between them.
There is a possible way that this communications would not be detected by our radio receivers around the world? ...
- 9
2
votes
1
answer
275
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Fresnel-Kirchoff integral and Huygens principle
Consider a monochromatic, uniformly polarized, EM wave:
$$E(x,y,z,t)=\tilde E(x,y,z)e^{iwt}$$
If on a certain plane $z=z_1$ the field $\tilde E(x_1,y_1,z_1)$ is known, we can find $\tilde E(x,y,z)$ on ...
- 1,904
2
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1
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218
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Laser flux power density and Raman scattered radiation
I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter Larkin. In a section entitled The Raman Scattering Process, the author says the following:
The intensity of ...
- 889
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72
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Speckles max intensity paradox
Wikipedia says (link) that in the limit of many interfering waves the distribution of intensities (which go as the square of the vector's length) becomes exponential
$${\textstyle P(I)={\frac {1}{\...
- 11
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49
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How to explain light beams in terms of wave theory?
How can we explain the formation of light beams in terms of wave theory?
According to wave theory, shouldn't the source point of beams emit radiation omnidirectionally, rather than a concentrated ...
- 533
2
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2
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42
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Can an electromagnetic wave be pulsated at the same frequency of the wave itself?
This is a thought experiment that's been bugging me for some time and I haven't been able to find any literature on this topic. I am not a physicist, please bear with me :).
Suppose I have a 500nm ...
- 25
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16
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Does a laser's listed wattage or joules include the frequency? Or just the amplitude?
In other words, if the number of photons in two different lasers is the same, but the second laser has a higher wavelength, does the second one have more 'wattage' or more total joules?
(Since higher-...
- 4,509
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169
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Infinite universe and the impossibility of monochromatic light and infinite plane waves
I recently asked a question relating to this excerpt from the textbook Optics, fifth edition, by Hecht:
Mathematically, the plane wave extends out to infinity in all its directions, and, of course, ...
- 889
4
votes
2
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456
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Non-monochromatic (multi-wavelength?) lasers
I was recently doing some reading on lasers, and I came across the fact that truly monochromatic light is impossible, which then obviously implies that truly monochromatic lasers are impossible. But ...
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42
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Laser emission frequencies: does that physically represent the frequencies if it was turned on for infinite time?
Consider you have a laser that has a given emission spectrum.
Does this emission spectrum physically represents the electromagnetic field it would emit if it was turned on for an infinite amount of ...
- 1,450
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34
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Will a magnet diffuse/defocus a laser?
I have read through hundreds of questions here and we discuss why light is not bent by an electric or magnetic field (at least not at easily visible levels in the classical sense), but that there is ...
- 121