ATM Easy way to estimate Angstrom ratings?

["Bill T." <twentiethwave@hotmail.com>]

We've been talking about mirror polish in terms of Angstrom ratings.  20 
Angstroms is attainable, 10 Angstroms is attainable with meticulous 
technique, plate glass may allow 5 Angstroms, etc.

Is there any easy way to estimate where a mirror surface stands in Angstrom 
terms?  We use non-visibility of a flashlight caustic as a forgiving test 
for surface polish, and non-visibility of a solar caustic or laser beam as 
much harder tests.  What are the approximate Angstrom ratings required to 
"pass" these various tests?  Would a laser dot become invisible at a small 
enough Angstrom rating?  Are there other techniques?

Bill T.


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