Re: Is there such a thing as in-phase and coherent white light?

On Mar 5, 7:40=A0pm, "Green Xenon [Radium]" <gluceg...@xxxxxxxxxx>
wrote:
Hi:

Is it possible to generate coherent white light? This is sorta like
laser light except it gives out all wavelengths of visible light at
equal intensities at the same time. Is this possible?

Thanks,

Radium

It is possible, in principle, in a sense. There are high speed pulsed
lasers available now, such as the Ti:sapphire laser. This laser
generates very short pulses of light, about 10E-15 seconds long or
less, and thus has a spectral width of about 10E15 Hz. The output
from these lasers is a very brief burst of EM radiation, just a few
cycles long, that repeats at about 80 MHz. If a similar device could
be built that would emit something closer to a train of delta
functions, then the emitted spectrum could approximate white light.
If such an output was analyzed with a spectrometer, one would find
many many narrow band peaks spaced at 1/(the pulse repetition rate).
The number of these peaks would be inversely proportional to the width
of the individual delta function pulses.

This beam could be considered coherent since the EM waveform repeats
periodically. If the repetition rate was 300 mHz, then the
fundamental waveform would repeat every meter or so, thus you could
get interference between beams that differed in path length by n
meters, where n is any integer.

I know of no devices that can do quite this at present.

Rich L.

.

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