Re: ATM Beyond the fan

[Steve JB Bouton <sjbbouton@juno.com>]

Well, it looks like that I'm not the only one that's thought of this. 
The biggest stumbling block to me was how to mount these devices to the
mirror.  Glue them to the mirror?  I think that they (and the related
heatsinks, fans, etc.) would get in the way of the mirror cell.  And the
waste heat could be a problem.

So, I came up with this idea: use a fan blowing past an array of Peltier
devices with heatsinks on the cold side.  The hot side is mounted to a
heat exchanger, similar to that of the Cookbook Camera design. 
Circulating coolant pulls the heat clear of the main mirror.  How much
cooler will the air be past the devices?  Until a protoype is built, I
have no idea how effective it would be.  But if it works, there would be
nothing to mount to the mirror, and no worry about the heat rising and
creating turbulence above the mirror.

On Thu, 21 Feb 2002 09:15:38 -0700 "Chuck Hards"
<chuckh@companionsystems.com> writes:
> 
> Has anyone tried attaching a Peltier heat-pump to the back of a 
> mirror, or
> an array of them?  The heat produced by the "hot" side could be 
> pulled away
> by a rear-mounted fan blowing backwards, straight out of the tube.  
> The
> "cold" side can get SO cold that it may be able to cool a mirror 
> much faster
> than a fan alone.  It doesn't address immediate boundary-layer 
> problems on
> the mirror's face, a small fan may still be needed if you're in a 
> hurry, but
> it may shorten appreciably the total cool-down time required.  I can 
> tell by
> recent posts that some people still aren't convinced that active 
> cooling is
> good insurance.
> 
> You know, you could even use one in an opposite configuration to 
> heat an
> eyepiece, kind of a high-tech "eyepiece cozy".
> (Sticking your tongue to the flagpole in winter is nothing compared 
> to
> getting your eyeball stuck on a Plossl......just eliminating the 
> "brain
> freeze" is a step in the right direction!)
> 
> Just an idea, perhaps more practical than a "levitating secondary"!
> 
> C'mon, Richard, let's hear it.  Dig into this one!
> 
> Chuck
> 
> 

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