We describe refractive x-ray lenses with a parabolic profile that are genui
ne imaging devices, similar to glass lenses for visible light. They open co
nsiderable possibilities in x-ray microscopy, tomography, microanalysis, an
d coherent scattering. Based on these lenses a microscope for hard x rays i
s described, that can operate in the range from 2 to 50 keV, allowing for m
agnifications up to 50. At present, it is possible to image an area of abou
t 300 mu m in diameter with a resolving power of 0.3 mu m that can be incre
ased to 0.1 mu m. This microscope is especially suited for opaque samples,
up to 1 cm in thickness, which do not tolerate sample preparation, like man
y biological and soil specimens. (C) 1999 American Institute of Physics. [S
0003-6951(99)03726-2].