From: John Murray 
To: atm{at}shore.net
Reply-To: John Murray 


Morning All,
        I've almost finished the tidying up and rearragement of my
computer/grinding/polishing/garage/utility room. Hopefully I'll have
another three sets later today that I can post out. I hope to finish this
by machine as the back isn't really up to it. However, if necessary I guess
I'll have to bite the bullet.

Cheers

John Murray
Whyalla
South Australia
Check our web page at http://astronomy.sa86net.com ATM and M-O-M stuff.
Latest Ronchigrams only at http://www.users.bigpond.com/imasloth/


> -----Original Message-----
> From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of Mark
> Holm
> Sent: Tuesday, 5 August 2003 9:50 AM
> To: atm{at}shore.net; imasloth{at}bigpond.com
> Subject: ATM Sixtests Results for John Murray's 200 mm O.D. mirror as of
> August 4, 2003
>
>
>
> Sixtests screen shots for John's  Foucault test results as of August 4,
> 2003 (the data with 4 zones and 3 measurement sets) can be seen at:
>
> http://users.telerama.com/~mdholm/atm/murray/murray1.html
>
> I don't claim to be a figuring guru, so I will let others suggest the
> best  techniques for improving this figure.
>
> I do know, from hard experience, that it is possible to improve a mirror
> like this, but it may not be very straightforward, at least not for the
> inexperienced.
>
> You can see from the first plot one of the main reasons I suggest that
> testing in more zones is probably a good idea.   The residual errors,
> after fitting a parabola, have two maxima and two minima.  This is the
> theoretical limit for four data points.  There is no redundency in the
> data at all, and, to a certain extent, Sixtests is just guessing how
> high those maxima and minima are.  These are good guesses based on the
> best mathematics available, but they still have a significant element of
> guesswork in them.   A few more data points would add a comforting
> degree of certitude to the estimates of the maxima and minima.
>
> Mark Holm
> mdholm{at}telerama.com
>
>
>

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