Blowing air at mirror surface was Re: [ATM] Re: ATM Digest, Vol 20,Issue 26

["Jean-Guy Moreau" <jgmoreau@cablevision.qc.ca>]

It is very easy to see the effect of blowing air on a mirror
while performing the Foucault test, enlightening :)

Jean-Guy


----- Original Message ----- 
From: <OPTIXWIZ@aol.com>
To: <atm@atmlist.net>
Sent: Wednesday, August 24, 2005 11:21 PM
Subject: [ATM] Re: ATM Digest, Vol 20, Issue 26


> Russell Jocoy's question on whether a fan blowing across the optical face of
> his telescope's primary mirror would affect image quality at the eyepiece is
> well taken.
>
> Also, Mark Holm's advice and references are quite relevant.
>
> However, Bryan Greer, Alan Adler's sometimes co-investigator, does not seem
> to grasp the virtually revolutionary significance of Alan Adler's
> anti-convection cell "forced ventilation." Adler's process work's virtually 
> instantly. As
> soon as the fan reaches full speed, the full effect is seen at the eyepiece.
> There is no waiting for the primary mirror to reach thermal equilibrium with 
> the
> air around it. Using Adler's process, the supposed resolution gap between
> good reflectors and good refractors is dramatically narrowed. Adler's own
> excellent 8-inch "home-built" Newtonian will make ANY 7-inch apo sweat!
>
> Adler's process makes use not of laminar flow, but turbulent flow, which
> "sweeps" away the "thermal boundary layer" and convection cells surrounding 
> the
> optical surface of the primary mirror.
>
> As Mark Holm notes, it is essential that the fan not impart perceptible
> vibration to the telescope. Alan Adler has researched this. My recollection is 
> he
> has found that Sanyo muffin fans, the ones having ball bearing bearings,
> mounted with rubber damping feet against the telescope tube, performed very 
> well.
>
> Wishing you .99 Strehls,
>
> Gene Cross
> Fremont, CA USA
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 

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