> I can't find the equations for the dispersion of laser beams, but I
> would have thought that at a distance of 300km the beam would so wide
> that it wouldn't make an effective weapon even against black targets.
(Assuming you mean 300.000km or 1 lightsecond):
That depends on the wavelength of the laser. Diffraction increases
directly pro****tional to wavelength, and decreases with lens size. An
(infra)red laser will paint a huge area where an UV or Xray laser will
still be focused to a few centimetres.
If you have a big enough ****p, you might use huge lenses, but these
will of course be inviting targets.
Now it appears to be a no-brainer to simply always use high-frequency
lasers (remember wavelength is 1/f), but on the other hand, low-
frequency lasers appear to produce a lot less waste heat, i.e. they
can be more efficient. Project Rho says that a high-freq laser may
have up to 20% efficiency, whereas low-frequency lasers can have up to
65%. Since it produces less waste heat, it can fire more often, albeit
at lower ranges.
> A laser is useless as a point defence weapon against unsilvered kinetic
> slugs. You take just as much damage from a kinetic slug that's been
> melted by a laser as from a solid slug.
Unless you can outright va****ize the slug, I still see two possible
effects:
1. the beam energy ionizes the (molten?) slug. A strong enough
electromagnetic field might be able to divert the now charged slug.
Haven't done any equations on the matter, but it seems reasonable.
2. The laser might not even be out to destroy the slug, but just
attempt to inflict an impulse to change its course. If the laser zaps
the slug at, say, 10.000km distance, even a fraction of a degree
should make the slug zip past the target.
Cheers
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