Re: [ATM] PLOP Figures

[Mark Cowan <toolontop@yahoo.com>]

Hi Mark:
   
Yes, I agree entirely about RMS vs PV provided that
RMS is available from good sampling or may be
extrapolated from PV in measurement.  I was just
quoting the first as an example for comparison - the
RMS was 1.5e-6 vs 1.56e-6 for the less optimized
initial (and quicker) run.    The RMS/PV ratios in the
examples run from a bit more than 5 to a bit over 6,
and one would always pick the better RMS - but given
the support systems modeled here I think it's unlikely
for the PV to be terribly misleading, and it is more
intuitive to many people.  Granted the latter does
make it harder to realize the RMS additive nature of
wave defects in the entire system.


RE the Monte Carlo - if that's what it does, you are
right - my error.  When I've tried it all that I get
is one run and it stops, no matter the input, so it
may be user error. Matt didn't specify the measurement
but when I read:

>6-point
>1.32996e-06 Av. Error
>1.34398e-06 Max Error

>9-point
>1.76221e-06 Av. Error
>1.76221e-06 Max Error

it looks more like a deviation not an absolute, so I'm
just left being confused about what it means.  Any
insight would be useful - I would like to be able to
model fabrication error and get something useful to
guide construction!!

CHeers,
Mark Cowan
Salem, OR
> I interpreted the Monte Carlo results as the worst
> (greatest) RMS 
> deformation predicted for each cell design during
> the Monte Carlo run.  
> As such, it is appropriate to evaluate these the
> same as the nominal RMS 
> deformations.
> 
> After being chided by Jim Burrows and others for
> some time, I have come 
> around to placing the greatest emphasis on RMS
> results.  I should have 
> done so long ago, since the science and math are
> both sound, and not 
> that hard to understand.  (I do have the advantage
> of a reasonable 
> background in math and physics, so it may be easier
> for me than for some 
> others.)  I have a Strehl ratio calculator at my
> mirror cell web page 
> that can help put RMS values into perspective.

I've seen it!



		
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