Tagged Questions
1
vote
2answers
50 views
Selectively visible laser beam with a controllable means
How can parts of a laser beam be made visible while others left invisible using something electronically controllable (for example, another laser beam crossing it, or a magnetic field, or heat, etc).
2
votes
1answer
104 views
How would one generate Brownian light? What would it look like?
When light is an equal mix of all visible frequencies, we call it white light.
By analogy, sound that is a mix of all audible frequencies is called white noise.
For sound, there is an additional ...
9
votes
2answers
697 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 ...
6
votes
2answers
464 views
Why do green lasers appear brighter and stronger than red and blue lasers?
This is mostly for my own personal illumination, and isn't directly related to any school or work projects. I just picked up a trio of laser pointers (red, green, and blue), and I notice that when I ...
1
vote
1answer
76 views
Ideal four-level Gain Medium (or just any old gain medium)
What exactly is happening in a laser's gain cell when the irradiance is greater than the saturation irradiance?
Also can someone offer a clear conceptual treatment of the gain-coefficient and its ...
0
votes
1answer
105 views
Can the inverse of a laser exist?
Speaking as a layman, I understand a laser works by exciting an electron so it returns to rest by emitting a photon. Is it feasible to 'damp' the energy level/s of an electron so it absorbs energy ...
5
votes
2answers
267 views
How does infrared light 'erase' phosphorescence on zinc sulfide?
I found some sheets of zinc sulfide in my basement that phosphoresce green for up to 24 hours or so after exposure to bright light in the violet range or shorter. One of the first things I tried was ...
3
votes
2answers
684 views
Can 2 beams of ultraviolet light intersect and be visible where they intersect?
Is it possible that if you have 2 ultraviolet lasers, that are invisible to the human eye, and if you aim their beams to intersect at some point, that the place of intersection will show a lower ...
3
votes
2answers
533 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 ...
