Re: [ATM] Foucault/interferometry comparisons

["vladimir sacek" <vlad@copper.net>]

Steve Koehler wrote:

> My main point is that when Foucault and interferometry disagree (and they
don't always), it seems that Foucault sees the mirror over-corrected with
respect to interferometry. <

Nice presentation. The examples do indicate that Foucault does tend to see 
mirror surface flatter than interferometry. One thing that may be worth 
checking out is whether the zonal readings are obtained with the use of both 
terms for the longitudinal radius displacement (i.e. h^2/2R + h^4/4R^3 for 
moving source), or only the main term. If only the main term is used, a 
perfect mirror reads as overrcorrected (i.e. the outer zonal radii measure 
progressively longer than what they are "supposed" to be). Mainly 
negligible, but can become less than that for larger fast mirrors. This is 
of course, well known, but  it may have been neglected in some cases.

Vlad 


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