Monochromatic focusing of subpicosecond x-ray pulses in the keV range

An effective x-ray optical method to focus keV x-ray pulses shorter than on e picosecond by using spherically or toroidally bent crystals is presented. The spectral, spatial, and time-dependent properties of focusing by two-di mensional bent crystals are calculated by considering geometrical effects, physical limitation in high performance crystal optics, and reflectivities obtained by x-ray diffraction theory. These properties are compared with fi rst experimental results of focusing x rays from a plasma created by a lase r pulse with 4.5 mJ energy and 100 fs pulse length. The x-ray signals, simu ltaneously obtained from a von Hamos spectrometer and two-dimensional bent crystals are compared and found in good agreement with theoretical data. Th e possibilities and aspects of laser pump x-ray probe experiments using thi s type of x-ray optics system and currently available laser systems are dis cussed. (C) 1999 American Institute of Physics. [S0034-6748(99)05002-9].