Re: Practically achievable beam divergence for white, non-coherent light

From: Joe D. (joe_at_nospam.invalid)
Date: 02/28/05 

Date: Mon, 28 Feb 2005 01:44:52 -0600

"Bob May" <bobmay@nethere.com> wrote in message
news:1109536513.159705@news-1.nethere.net...
> You can get there from here by imaging the sun with a short focal length
> mirror and then using that small image at the focus of a long focal length
> mirror, gain a small divergence angle.
> The sun (and the moon, for that matter) is 1/2 degree wide. To get the
> desired angle, you will need to have the second set of optics to be about
> 10
> times longer than the first ste.

By this you mean the diameter of the secondary has to be 10 times
the diameter of the primary mirror?

Or that somehow after a parabola collect sufficient light, and after
it bounces off the secondary it most go through a 1:10 beam expander
to produce the desired divergence?

My question is can any mirror-based optics produce a solar
beam with a divergence of 0.06 degrees (1 milliradian).

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