Abstract

Until recently, the use of reflective optics at short wavelengths was limited by the low critical angles of minor materials. Single coating mirrors are impractical for energies above ~ 40 keV, because the approximate relation E[keV]· ·θ [mrad] ≤ √ 80 · Z, (where θ is the incidence angle and Z is the atomic number of the mirror material) must be fulfilled. For neutrons the use of graded d-spacing multilayers, so-called supermirrors, has helped to considerably increase the usable angles and has facilitated the construction of flux concentrators at energies where single coatings do not perform well^1,2,3. We have previously reported on supermirrors for high energy x-rays^4,5. For energies above 40 keV and away from absorption edges, supermirrors show significant reflectivity out to E[keV]· θ[mrad] ≤ 6.2·10³/d_min[Å], where d_min is the minimum period of the supermirror. In this summary we describe the first focusing of a high energy polychromatic x-ray beam with a W/Si supermirror.

© 1994 Optical Society of America