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Problems with beaming
- To: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)
- Subject: Problems with beaming
- From: Steve VanDevender <email@example.com>
- Date: Sat, 6 Apr 1996 11:37:35 -0800
- Cc: KellySt@aol.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com, David@InterWorld.com, firstname.lastname@example.org, DotarSojat@aol.com
- In-Reply-To: <199604061858.AA08809@student.utwente.nl>
- References: <199604061858.AA08809@student.utwente.nl>
Timothy van der Linden writes:
> To Lee,
> >There are two problems really. First of all; there is the inverse square
> >law, the intensity (and therefore the power) of radiation decreases as the
> >inverse square of the distance. I have not seen anyone's calculations here
> >take into account the amount of power that must be generated HERE in order
> >to provide a reasonable amount of power THERE.
> Yes, but lasers keep a tight beam and thus their diametre (cross-section)
> does not increase with distance and the energy-density (per surface) stays
> the same.
> So I don't see a problem here.
Actually, practical lasers do diverge with distance. Coherency does not
For example, lasers that work by reflecting light between two mirrors
produce a primary beam where an integral number of wavelengths N falls
between the mirrors, and a secondary annular beam where N+1 wavelengths
fall between the two mirrors, with a slight angle between the primary
beam and the secondary annular beam. The angle isn't noticeable in
typical lasers and laboratory distances, since it's on the order of
milliradians; shining the laser over a long enough distance would show a
bright spot surrounded by a ring, rather than just a spot (assuming your
mirrors are that good, anyway).