Re: Zone plates for a body cap

----- Original Message -----
From: "Guillermo" <penate@rogers.com>
>
> I gather that by "aperture of the zone plate" you mean the size of each of
> the rings. Mr.Pinhole formula is what the scientific community uses for
> their high-tech uses of zone plates and my non-scientific tests (focusing
> aerial images produced by zoneplates) have confirmed that. Other use
> slightly different formulas.

I was reading my own post and it seems not to be too clear.

What I meant was that when I mount zone plates on my 4x5 view camera and
focus on the aerial image until it is a "sharp" as they would be, the
distance zone plate to film plane matches very closely with what the formula
Radius = SQRT(wave length x focal length x ring#) would predict.

Now, the formula can also be written as Diameter = 2 x SQRT(wave length x
focal length x ring#). Some people use formulas slightly diferent, what
they change is that number "2", Patton for instance, uses 1.86
http://www.stanford.edu/~cpatton/zoneplatemath.htm

Guillermo
Received on Fri Oct 25 16:22:48 2002