[ATM] "Best" mirrot shape
Peter De Baan De Baan
pdebaan at hotmail.com
Thu Oct 1 06:58:59 JST 2009
Me thinks that I will close my eyes and see past infinety even without a telescope mirror
> From: richard1941 at gmail.com
> To: wa4guu at verizon.net
> Date: Wed, 30 Sep 2009 14:26:47 -0700
> CC: atm at atmlist.net; almansor at dslextreme.com
> Subject: Re: [ATM] "Best" mirrot shape
> It all depends (praphrasing president Clinton) which definition of
> "best" is best. My definition was the smallest spot size over the
> entire focal plane (usually 2" diameter).
> Sent from Richard's iPhone
> On Sep 29, 2009, at 13:43, "Jerry" <wa4guu at verizon.net> wrote:
> > Hello Richard,
> > I think that Hyperbolas are best single surface telescope for focusing
> > objects beyond infinity.
> > The parabola is best for objects at infinity.
> > An over-corrected ellipse (0 > b > -1) is the surface for things
> > beyond the
> > center of curvature but less distant than infinity.
> > All the astronomical objects that I have seen have been closer than
> > infinity. So that under-corrected ellipse is the one I would want
> > for the
> > one surface telescope.
> > Now it may be that atmospheric refraction might refract diverging or
> > nearly
> > parallel rays to converging similar to rays coming from a point beyond
> > infinty. But in that case the atmosphere is one surface and the
> > mirror is
> > the second.
> > Maybe if we made a "perfect hyperbola" we could see other universes.
> > Jerry
> > -----Original Message-----
> > From: richard schwartz
> > And it may come as a shock to some that the best shape for a single
> > mirror
> > telescope may actually be a hyperbola, not the standard parabola.
> > (I was
> > amazed to find this by ray tracing a long time ago.)
> > Now go figure... some more...
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