Recently physicists have managed to build "attosecond lasers", lasers
which emit pulses 10-18 seconds long, interrupted by much longer periods of darkness (at least 10-14 seconds). Before them, lasers emitting
femtosecond (10-15 seconds) pulses have been around. Assuming they
produce visible light, what colour is it?
(In reply to
re: I see - I think by vswitchs)
One question about the light not being monochromatic. Since it is emitted from a laser, it tends to be highly monochromatic. So, I'm wondering whether you're saying for purposes of this problem we can allow the spectrum to be as wide as needed?
The monotonicity of laser light is because the atoms which constitute the "lasing" medium contain electrons which are excited to fixed energy states. When, an atom decays from the excited state to the ground state, it releases a characteristic photon. This photon has fixed frequency, since the energy gap between the excited state and ground state is fixed (E=hv).
An example of this is the He-Ne laser which releases a characteristic red light at 632.8nm.
http://en.wikipedia.org/wiki/Helium-neon_laser
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Posted by gregg
on 2006-10-12 01:06:36 |
re(2): I see - I think
