Re: ATM Waineo null test sphere figure question

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

<<
Bob,
Great idea not tried using a 'grey' mask and matching to an external value
before - I must try that on my next mirror - down to the art shop for some
grey card I think
Many thanks
Francis
>>
Since I use a camera when looking at the mirror in the Foucault test, I just
have a light bulb in the room which produces a nice level of light on the
white cardboard that I'm using for masks.  It is the light level that is
desired, not necessarily the brightness of the mask itself.
If I was looking directly at the light past the KE then I would probably be
desirous of using a green color (I'm using a green LED on the tester) to
balance the color of the mask to the color of the light coming back.
I will say that the diffraction you get from an edge takes on a very
interesting appearance when doing this.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
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