To: atm{at}shore.net
From: jsgrmfg{at}gracemfg.com
Reply-To: jsgrmfg{at}gracemfg.com


<<<<<
Couldn't the center of the mirror be defined as the digital center of the
image?  Just how accurate does the center need to be known?  For example,
lets say a 20" mirror occupies 300 pixels in width, we should know the
center within 0.066" (or possibly better).

I thought the critical part was knowing how much the WIRE moved laterally
rather precisely, then measure where this moved the shadow on the image..

Looks like its about time to modify Robo-Foucault to do the LWT as well :)

Take Care,
James Lerch
>>>>>

   The diffraction ring at the edge of the mirror - even
a mirror with a good edge - causes a photo of the mirror to be pretty much
burned out on one edge and very dim on the other.  This makes determining
the diameter in pixels and, by reference, the center a little iffy.

Besides, some of us obsessive types have never heard of sufficient
precision.  If we can think of a way, no matter how elaborate and
inconvenient, to reduce a three pixel uncertainty to a two pixel
uncertainty, we'll go for it :-)

Jim Sturtevant

--- BBBS/NT v4.00 MP