Re: [ATM] convex secondary

["Jonathan Lavoie" <atm@lavoielactee.net>]

----- Original Message ----- 
From: "Mike Lockwood" <melockwo@uiuc.edu>
To: <atm@atmlist.net>
Cc: "Jonathan Lavoie" <atm@lavoielactee.net>
Sent: Thursday, March 03, 2005 12:07 PM
Subject: Re: [ATM] convex secondary


>
>> I heard of another test for convex but can't remember where. The idea was 
>> to test from the back through a liquid of similar refraction index that 
>> is in contact with the back surface, and just do standard foucault 
>> measurement. Anyone heard of it?
>
> I've heard of using Glycerin, because it matches the index of refraction 
> of Pyrex.
>
> Seems like if you polished the front and back of the tool and the 
> secondary and then put the two together with glycerin between (flat 
> surface to flat surface, so that the curved surfaces were facing out) then 
> you could test through the tool and mirror with minimal refraction.  This 
> is either the test I'm remembering, or it's close to this.  I don't know 
> how much of a problem testing through the Pyrex would be.
>

At 5:00 am this morning I was not able to sleep then your idea became clear 
in my mind.
I sketched it here: http://www.lavoielactee.net/images/convex.gif
I think this looks like the test I read about but still can't find where.

What other think of this idea? Would this arrangement enable me to test with 
no need to account for any refraction effect?

Jonathan 

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