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On 04/15/2007 05:32 PM, Ludwik Kowalski wrote:
Here is an application in which a pinhole camera can be used today. (I
do not remember where I read about this, years ago.) Suppose you want
to know about distribution of X rays at the surface from which they are
emitted. A lead sheet with a pinhole, plus an X-ray film, is a
solution. The film will produce "the image" of the source. Yes, a lens
focusing X-rays, if it existed, would be desirable.
Fresnel zone plates for focusing Xrays have been around for
many years.
For example:
S. J. Spector, C. J. Jacobsen, D. M. Tennant,
"Process optimization for production of sub-20 nm soft x-ray zone plates"
http://xray1.physics.sunysb.edu/~micros/publications/papers/ spector_jvstb_1997.pdf
They are a royal pain to make, but they work a lot better than
pinhole cameras.