From: Mike Lorrey (mlorrey@yahoo.com)
Date: Mon Apr 07 2003 - 21:52:54 MDT
--- Adrian Tymes <wingcat@pacbell.net> wrote:
>
> ...it's a *lens*. A rather obvious type, it seems to
> me. Yes, lenses have all kinds of uses; this is just
> putting a lens inside a carefully-created flat sheet.
> I fail to see the significance over what we already
> had, for instance how it can significantly improve
> performance over presently available lenses in any of
> the areas you mentioned. Could you explain what I am
> failing to grasp, please?
The reason that most astronomy today occurs with reflector telescopes
rather than refractors is that the result of light passing through
different thicknesses of glass at different points in lenses, as well
as the curvature of the lenses themselves, causes reductions in
resolution. Note how a prism bends light. Blue wavelengths bend less
than red ones. As a result, in a refractor telescope, bluer wavelengths
have a longer focal length than redder wavelengths.
Since the speed of light is less in glass than in air, light passing
through the thick center of a convex lense slows down more than that
passing through the thinner edge. This reduces the ability of temporal
focus, where light packets in parallel when entering the telescope are
shifted by what thickness of glass they each pass through.
If you have a flat lense of constant thickness, these problems are
greatly reduced. It also greatly reduces the weight of the telescope,
since you don't need to use so much glass mass...
=====
Mike Lorrey
"Live Free or Die, Death is not the Worst of Evils."
- Gen. John Stark
"Pacifists are Objectively Pro-Fascist." - George Orwell
"Treason doth never Prosper. What is the Reason?
For if it Prosper, none Dare call it Treason..." - Ovid
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