TABLE OF CONTENTS B.Lengeler, C.Schroer, J.T mmler, and B.Benner
Zweites Physikalisches Institut, RWTH Aachen
Aachen, Germany
A.Snigirev and I.Snigireva
European Synchrotron Radiation Facility ESRF
Grenoble, France
Refractive lenses made out of glass are among the most widely used optical components for visible light, with a broad spectrum of applications in focusing and imaging. For a long time, refractive lenses for the hard X-ray range were considered unfeasible. The weak refraction of X rays in matter and their strong absorption seemed to be insurmountable obstacles. In 1996, it was shown that these obstacles can be circumvented and that linear lenses, shaped as a row of drilled holes in a bloc of aluminum or beryllium, can be manufactured with about 1 m focal length and a transmission of a few percent for a geometric aperture of 1 mm. 1 3 In the meantime the concept and the manufacture of the lenses have been improved considerably. The new lenses have a parabolic profile and rotational symmetry around the optical axis. Hence, they focus in two directions and are free of spherical aberration. They are genuine imaging devices, like glass lenses for visible light. 4 6
It has been shown in an extensive paper that most formulas known from ordinary optics, like those for the focal length, for the imaging properties and for the lateral and longitudinal resolution can be transferred to the X-ray regime.6 The main difference is in the effect of absorption and surface roughness...
