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Re: A list of textbook miscon: spatial coherence






-----Original Message-----
From: John Gastineau <gastineau@mindspring.com>
To: phys-l@atlantis.uwf.edu <phys-l@atlantis.uwf.edu>
Date: Friday, February 13, 1998 4:25 PM
Subject: Re: A list of textbook miscon: spatial coherence


At 02:23 PM 2/13/98 -0500, SCIAMANDA@edinboro.edu wrote:

(At these wavelengths, even the frequency selectivity of the resonant
cavity is not the main contributor to temporal coherence (linewidth).)

Are you saying that a laser linewidth is not determined by the cavity?
In a standard HeNe classroom laser, the linewidth of the emitted light
is a small fraction of the Doppler-broadened spectral profile of the
neon atoms in the laser. In fact, for typical sizes of laser tubes, 25
or 30 cm long, two or three cavity resonance modes fall within the
Doppler profile. The line width for these lasers is determined almost
entirely by the Finesse (technical term) of the mirrors.

JEG


__________________________________

John E. Gastineau gastineau@mindspring.com KC8IEW


John,
Everything you say is absolutely correct. My statement is very badly worded
and does unintentionally imply what you inferred from it. It is incorrect
and I withdraw it! Thank you for the correction.
-Bob

Bob Sciamanda sciamanda@edinboro.edu
Dept of Physics trebor@velocity.net
Edinboro Univ of PA http://www.edinboro.edu/~sciamanda/home.html
Edinboro, PA (814)838-7185