Your underlying motivatiopn to pooh-pooh makes you
seem like a fool.

It is the optical path that determines the divergence, or otherwise
of the beam, by dispersion, diffraction, refraction mechanisms,
and not the coherence of the radiation.

(Cue rejoinder by Mrs.Nugatory, given 5 minutes or so, to look
things up on google, to say that monochomatic radiation is
unaffected by a dispersive medium.)

Brian Reay wrote:
"Plod's Conscience" wrote in message
oups.com...

Allowing for the lens that is used to produce the
straight line beam, the spot from the end was
easily picked out on a gravestone 1/4 mile away,
thus suggesting that a tight beam is being produced.


Laser's are coherent sources, the "ASER" stands for Amplification by
Stimulated Emission of Radiation- the crucial phenomena in the operation of
lasers and masers. The emitted photon is in phase with the stimulating
photon.