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.
_______________________________________________________
Ludwik Kowalski, a retired physicist
5 Horizon Road, apt. 2702, Fort Lee, NJ, 07024, USA
Also an amateur journalist at http://csam.montclair.edu/~kowalskil/cf/