Re: [ATM] Thermal mirror deformation

["Scott Milligan" <starzkey@charter.net>]

Thanks Ric:  I was able to track down in this list archives) a link to an
article summarizing the Apache point Telescope (Sloan survey) design and
construction.  The link was posted by Mike Peck on Feb 16 2006.  The linked
paper does indeed describe a primary mirror cooling system designed to suck
ambient air into a central plenum, from which it is then distributed to
circulate across the back surface of the mirror face sheet (the substrate
was a Hextek gas-fusion part).  The stated goal was to keep the optical
surface temp stable and within the ambient observatory temp by 0.1 - 0.2
degrees C; I did not see, however, any subsequent results summary that would
indicate whether or not this goal was met, but my initial reading was also
not completely thorough.

Anyway, it's is an interesting read for the TN; thanks for calling my
attention to it.


Scott Milligan
 
 

-----Original Message-----
From: Ric Rokosz [mailto:radicell2@yahoo.com] 
Sent: Thursday, August 31, 2006 8:43 AM
To: starzkey@charter.net; atm@atmlist.net
Subject: Re: [ATM] Thermal mirror deformation



--- starzkey@charter.net wrote:

> Someday, I'll get around to trying this idea, which has been kicking 
> around in the back of my head for years, but for now, I'll just ask 
> the group; Has anyone tried using a mirror with a central perforation, 
> mounted on a central hub that also functions as a plenum for sucking a 
> continuous stream of air from the region in front of the mirror 
> surface and exhausting the air out the back?
> The air might enter the plenum via a multitude of radially oriented 
> holes, located a small distance in front of the optical surface.

Didn't Tom Kujic report on this for the newer Apache point telescope about a
year ago?The pro's have tried/done this from what I recall from Tom's
post.He also had a link to an article if I'm not mistaken.

Ric

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