Re: Colonists and Weapons

Tomb wrote:

> Why is a laser a good thing? Recharge from a portable solar cell. Low
> logistics demand potentially. Why is a laser fragile? Maybe it uses a
> big fiber rod as its core, and thus hasn't got conventional optics and
> has effectively a "barrel" very similar to a rifle that is about as
hard
> to jar or adjust (zero). What else makes a laser a good thing?
Multiple
> modes. Eh?

Vaporising a 20 cm long wound channel with a sectional area of	one
square
centimeter requires delivering 45 kilojoules to the target.  Hopefully,
this
is fatal.  Ignoring all losses and assuming that all efficiencies are
100%,
the solar collector area is sixty square metres (divided by the time
between
shot in seconds), for Earth.  Clouds, haze, dirt, and vegetation will
increase this, and it would be wildly optimistic for the efficiencies of
either the laser or the solar collector to get above 50%.  Until someone
starts burning holes in living things, we will not know how uaseful the
45
kilojoules guess is.

Your wide beam mode will require huge amounts of power.  A seven watt
laser
feels warm when the spot impinges on your person (and it WILL blind
you),
but a seven watt wide beam is barely adequite to read by.  Felling warm
in a
wide beam will require many kilowatts of power (I have stood under six
kilowatt incandescent bulbs).  Injuring by any mechanism besides
blinding is
probably right out.  Lasers do damage by having a very large energy per
unit