To: atm{at}shore.net
From: Jim Burrows 
Reply-To: Jim Burrows 


At 14:27 2003-04-28 -0700, Scott Berfield wrote:

>So how much deviation from a sphere
>are we seeing when we see things like surface roughness, ripple, etc?

Texereau sez, p. 75, changing to metric, minimum detectable surface
deviations are 1 to 10 nm.  I dug up a 6-year old e-mail (which I don't
understand anymore) that proved using the eye's contrast sensitivity of 5%
that one could see .01 wave on the surface = 5.5 nm.

This suggests the roughness one sees may not be optically significant, also
backed up by Texereau, p. 62, showing Foucaultgrams of perfectly horrible
looking roughness that "...would pass quite unnoticed when observing a
star at the focus."

         -- Jim Burrows
         -- mailto://burrjaw{at}earthlink.net
         -- http://home.earthlink.net/~burrjaw
         -- Seattle N47.4723 W122.3662 (WGS84)

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