On Wed, Sep 27, 2017 at 07:08:03PM -0700, Evyn MacDude wrote:
> <div dir="ltr">Have any of y&#39;all ever considered how much damage and range of a communications laser does if used as a weapon?<div><br></div><div>I have been contemplating a ground survey vehicle equipped with a coms laser that has enough range to talk to something in Geo stationary orbit.<br><br>Lots of Niven being channelled here...<br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature">Evyn</div>

Negligible.  A handheld laser pointer could be easily detected at
geostationary orbit if pointed toward a suitable receiver in clear
weather conditions.  Some of them could be seen with unaided human
vision.  In bad weather conditions extra power wouldn't help much
anyway.  Presumably a purpose-built comm laser would be designed with
advanced modulation capability, a range of wavelengths for dealing
with various atmosphere types and some types of weather, and
auto-tracking - but no more power would necessarily be required for
the beam itself.

If it had been a photon drive, or a system designed to communicate
between star systems, then you might be approaching Niven territory.

On the whole though, a laser doesn't seem very well suited for
communication through an atmosphere.  There are too many things that
will block it.  Microwaves are better, but even they aren't that good
as anyone using a satellite service during a rainstorm will attest.
Comms lasers would be mainly suited for space communications.

Though if you wanted for some reason to make a comm system usable as a
weapon, and to avoid weather problems, there is a simple way to solve
both problems: say it's designed to cope with adverse weather
conditions by blasting a near-vacuum channel through the air, clouds,
birds, or any small vehicles that might cross the beam path.  ;-)

- Tim