Light Amplification by Stimulated Emission of Radiation. A means of creating coherent light by either driving an atomic or molecular transition in an optical cavity or firing a beam of electrons through an undulator.
9
votes
2answers
690 views
Is the “How to break the speed of light” minute physics video wrong?
I am referring to this video, on YouTube, by minutephysics, which has quite a lot of views.
In the video it states that if you flick your wrist while pointing a laser that reaches the moon, that the ...
2
votes
3answers
484 views
Recently publicized experiment on destructive interference between two laser beams
Recently I've had several non-physicist friends ask me, independently of each other, about an experiment where two collinear laser beams destructively interfere along a certain length. Everybody wants ...
2
votes
1answer
317 views
Can energy be extracted from clouds?
Can cloud charge imbalance be used as an energy source?
First off quite some energy must be present in clouds: a lightning path is quite long, and electrical breakdown of air requires about 1MV/m. ...
9
votes
4answers
948 views
Is it possible to observe interference from 2 independent optical lasers?
It seems that if the coherence length of a laser is big enough, it is possible to observe a (moving) interference picture by combining them. Is it true? How fast should photo-detectors be for ...
3
votes
2answers
530 views
Propagation of light in transparent media: absorption and reemission or scattering?
In the two Phys.SE questions What is the mechanism behind the slowdown of light/photons in a transparent medium? and Why glass is transparent? transparent media were discussed. But I'd like to clarify ...
10
votes
4answers
426 views
When lasers are used to cool atoms or ions, etc where does the heat go?
According to the first law of thermodynamics, sourced from wikipedia
"In any process in an isolated system, the total energy remains the same."
So when lasers are used for cooling in traps, similar ...
6
votes
1answer
327 views
Is the time reversed laser really a laser?
I'm looking at the time reversed laser and I was having trouble understanding why we call this device a laser. To me this device is more like the absorbers found in FDTD codes, something like a CPML.
...
3
votes
1answer
298 views
Focusing laser & off-axis illumination & diffraction limit
I've thought I had a good understanding how resolution enhancement tricks works for projection lithography, until I tried to understand if it's possible to get sub-diffraction performance for focused ...
7
votes
2answers
298 views
Fairly Broad Spectrum Light Source Options
I tried this sight before to find filtering options and got fantastic results, so let's try again!
I am setting up an experiment that requires light of two different frequencies (445nm and 350nm). ...
4
votes
3answers
165 views
Counterpropagating beams in a ring cavity lasers
Ring cavity lasers usually has a intracavity element like a optical diode to forbid standing wave pattern and, consequently, spacial hole burning and related instabilities. So, my question is: why to ...
3
votes
1answer
340 views
gamma ray lasers?
Is it really possible in the foreseeable future to create a gamma ray laser? I've read these two articles on Wikipedia:
the Hafnium controversy
Induced gamma emission
It sounds pretty amazing, ...
1
vote
1answer
145 views
What is 'tilt locking' of a laser cavity?
In another question, jasonh mentions a scheme for locking a laser to a resonant cavity called 'tilt locking':
The signal is used for locking the frequency of a laser to a high finesse cavity. The ...
