Re: ATM Robo Misalignment Calculations, did I do this right?

["Bob May" <bobmay@nethere.com>]

Interesting results.  When you did the video Foucault, did you have the
intensity of th light source low enough so that when the KE started cutting
the light beam, the camera didn't change the brightness or contrast of the
image?  I find that this part is fairly important as my testing of coated
mirrors is often off a bit if I allow for darker shades due to the fact that
the background brightness of the zones doesn't go to 0 but rather some
moderate value.  As a result, I test coated mirrors with the lightest of
grays that are commesurate with the shadows that are obtained.  Losing the
grayscale does affect the actions of the test.  I'll also note that I can
get changes in the KE position from the KE not being close to the center of
the lens.  I don't know exactly what is going on here but the lateral
position of the lens relative to the KE does make a difference in the actual
distances measured.  The effect is pretty minimal across the central part
but on one side or the other, it does become more pronounced, probably due
to the blocking of some of the light at the edge but that hardly makes sense
as the center zone also suffers from this problem, making the 0 reference
move in or out.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
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