Re: [ATM] Help needed with foucault

["Richard Ozer" <rozer@pacbell.net>]

I concur with Bob on this.  I was surprised to see an earlier post that 
suggested that the TDE was only a few mm wide and that the bright left rim 
was the "normal artifact" of a mirror's edge.  This is a pretty clear case 
of TDE.

You may want to consider using a Ronchi test in conjunction with your 
Foucault test.  For me, using a Ronchi test is easier for judging my 
progress in eliminating zone defects and surface roughness.

RO

----- Original Message ----- 
From: "Bob May" <bobmay@nethere.com>
To: <atm@atmlist.net>
Sent: Thursday, April 14, 2005 10:39 AM
Subject: Re: [ATM] Help needed with foucault


> The first photo shows the TDE while the other photos are so far from the 
> ROC
> that they don't really show anything.
> The TDE is about an inch in width or so.
> You also have a bit of roughness from not rotating your strokes often
> enough.  You should be doing almost each and every stroke in a different
> direction on the surface of the mirror in order to keep things smooth.
> You should also lengthen your strokes a bit to get rid of the central 
> hill.
> Bob May
> bobmay@nethere.com
> http://nav.to/bobmay
> http://bobmay.astronomy.net
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/ 

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