Re: [ATM] first light on a Lurie-Houghton

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

Now that I look at this again, then maybe it might be. With our setup, there is no way we can measure 1/10 of a degree!
Guy

Chris Todd <christopher.todd@gmail.com> wrote: Guy,

I was wondering whether you had determined the cause of the image
aberrations in your Lurie-Houghton.  Was it tilt in the corrector?

Chris

On 8/14/07, Guy Brandenburg  wrote:
> Then this might be it. Hope it is, because trying to get the actual parameters of the glass would be a real pain in the neck, and will risk breaking the corrector plates.
>
> vladimir sacek  wrote:
> Guy Brandenburg wrote:
>
> > I could tell that the corrector plates were not truly parallel to the
> > primary, but didn't have the means to fix and adjust that at the time.
>
> The only thing about Houghton corrector that has very tight tolerances is
> its tilt. It is roughly ten times as sensitive to it as Schmidt corrector,
> whose wavefront error in terms of the tilt angle t (in radians) is given by
> W=tD/48F^3, D being the aperture diameter and F the mirror focal ratio
> number.
>
> As little as 1/10 degree tilt would produce some 0.6 wave of centerfield
> coma (equivalent to somewhat over 1/3 wave of spherical aberration).
>
> Vlad
>
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Guy Brandenburg, Washington, DC
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