[ATM] "Best" mirrot shape

[Richard Schwartz]

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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