Compact soft x-ray reflectometer based on a line-emitting laser-plasma source

We describe a compact soft x-ray reflectometer for in-house characterizatio n of water-window multilayer optics. The instrument is based on a line-emit ting, liquid-jet, laser-plasma source in combination with angular scanning of the studied multilayer optics. With a proper choice of target liquid and thin-film filters, one or a few lines of well-defined wavelength dominate the spectrum and multilayer periods are measured with an accuracy of 0.003 nm using a multi-line calibration procedure. Absolute reflectivity may also be estimated with the instrument. The typical measurement time is currentl y 10 min. Although the principles of the reflectometer may be used in the e ntire soft x-ray and extreme ultraviolet range, the current instrument is p rimarily directed towards normal-incidence multilayer optics for water-wind ow x-ray microscopy, and is thus demonstrated on W/B4C multilayers for this wavelength range. (C) 2001 American Institute of Physics.