On Feb 7, 9:51 pm, MacFrag...@[EMAIL PROTECTED]
wrote:
> > It can help. It's harder to do than you might think, across the
spectra
> > involved, but yes, it is a plus.
> So a mirror that would reflect an infrared laser would not necessarily
> reflect an indigo or UV laser?
You can have a mirror which reflects exactly one or two specific
frequencies extremely well, but no mirror will be extremely
reflective across a broad range of frequencies. Against infrared
to visible to near UV lasers, I actually think the best defense
may be to let the light through. Diamond-like carbon is very
tough and very transparent. You can put a thick hollow shell
of diamond-like carbon around a thick hollow shell of aluminum
or some other reflective metal. Enemy lasers will va****ize
the aluminum, but leave the carbon layer more or less intact.
The va****ized aluminum will be trapped by the carbon shell,
so it'll resolidify. The result can be tough for the enemy to get
through, because it's somewhat self-healing.
> Working from the lesson that "there is no gamma ray mirror", do beams
> get exceedingly more difficult to reflect the shorter the wavelength
> is?
It sharply goes from doable at near UV to utterly impossible
at far UV. Beyond far UV, reflection is only possible at grazing
angles, and even then it's inefficient. This is because wavelengths
as small or smaller than the size of atoms see the smoothest
of all possible mirrors as bumpy.
> Or do you simply need different types of mirrors for infrared, visible
> light and UV?
A well polished aluminum mirror will do an "okay" job up to
near UV. Unfortunately "okay" more or less means any
serious weapons laser will still va****ize it anyway. Aluminum
is a great material to make a spacecraft hull out of. If a
weapon laser can't zap through aluminum, then it's a
pretty poor candidate for a weapon laser.
To get really awesome reflectivities, you need to go with
multi-layer dielectric coatings with spacings tuned to
specific frequencies at specific incidence angles. This
isn't a practical defense against enemy lasers since the
enemy is exceedingly unlikely to cooperate by shooting
at you with exactly the right frequency laser from exactly
the right angle. It's good for mirrors used by the weapon
lasers themselves.
> All this is part of a consideration what the hull surface of a
> space****p would look like in a belligerent setting. Since there is no
> (non-magical) way of hiding in space anyway (not with a power output
> in the GW range and up), I figured there's no point in trying to
> camouflage the hull (i.e. making it pitch black), and with your
> emissions announcing your presence anyway, appearing as a giant disco
> ball probably won't make it worse.
There are two armor schemes I tend to favor. My favorite
is no armor at all. From a mass budget perspective, it
seems to make more sense to use every gram for more
offensive weapons platforms, rather than invest anything
in defensive armor.
The other armor scheme I favor is thick diamond-like carbon
armor. For radiator panels, the strategy is to simply let
visible/UV lasers pass all the way through. Coolant fluid
runs in hollow channels in the carbon blocks. Enemy lasers
will locally va****ize the coolant fluid...no big deal, since the
fluid is va****ized in normal operations anyway. For the
main hull, the transparent carbon blocks are backed up
with thick aluminum or titanium or tungsten armor.
> The tactical consequence I see in effective anti-laser mirrors would
> be that lasers become a lot less useful. You'd have to aim at
> vulnerable spots like, for instance, engine nozzles, which would make
> maneuvering a lot more im****tant, and also significantly reduce combat
> distances (to both reduce lightspeed lag and actually be able to get
> on an evading opponent's tail). No more exchanging broadsides at
> 300.000km.
At 300,000km or more, visible/UV lasers would have to
be implausibly large and bulky to work. X-ray lasers
could be rather compact and 300,000km would actually
be short range for them. Those lasers can't be reflected
by any sort of laser armor. Even so, a thick layer of
diamond-like carbon is as good an armor defense as
you're going to get. It's nice and sturdy, with a high
melting point. No self-healing effect, of course. Carbon
that gets va****ized off the outer surface is lost forever.
Isaac Kuo
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