RE: [ATM] Figuring nightmare I need your help

["Brent Russell" <brussel@bpc.org.za>]

Hi jim,

Duh! Yeah I had entered the ROC as the focal length so it made somewhat
of a difference to my expected readings, however star testing shows too
a VERY over corrected mirror, so my readings are OK.
Brent



-----Original Message-----
From: Jim Burrows [mailto:burrjaw@earthlink.net] 
Sent: 02 October 2004 07:10 PM
To: Brent Russell
Subject: RE: [ATM] Figuring nightmare I need your help

At 2004-10-02 08:37 -0700, you wrote:
>F5.2 316mm diameter
>Zones centers:
>53.4mm
>97.5mm
>125.2mm
>147.7mm
>
>Readings are:
>0.0mm
>4.2mm
>8.7mm
>13.5mm
>
>As opposed to expected readings of:
>0.0mm
>4.0mm
>7.7mm
>11.5mm
>
>This gives me 3.25 waves over corrected....I need to remove glass at
>about 120mm radius. Sigh....
Brent,
There's something wrong. The ROC is 5.2*2*316 = 3286 mm, right? I ran 
your "expected" readings, assuming fixed source @ ROC, got surface RMS 
161.3 nm, best-fit conic b = -1.986, P-V 550 nm. This sounds close to
your 
3.25 waves overcorrected. If I run it moving source, it's even worse.
If I halve the "expected" readings, I get a nearly perfect parabola.
I also get a reasonable result if I halve your readings: RMS 29.2 nm, 
b=-1.174, P-V 110 nm, which would be almost passing (20 nm surface RMS).
I can't imagine how the readings got doubled, but if the latter is true,

full lap, COC stroke, ~ 2 minute spell.
Regards,
Jim Burrows 

---
Incoming mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.769 / Virus Database: 516 - Release Date: 24/09/2004
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.769 / Virus Database: 516 - Release Date: 24/09/2004

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.769 / Virus Database: 516 - Release Date: 24/09/2004
 

_______________________________________________
ATM mailing list http://www.atmlist.net/