  We demonstrate that vacuum forming of 10-cm diameter silicon wafers of
various crystallographic orientations under an x-ray permeable, flexible window
can easily generate spherically bent crystal analyzers (SBCA) and toroidally
bent crystal analyzers (TBCA) with ~1-eV energy resolution and a 1-m major
radius of curvature. In applications at synchrotron light sources, x-ray free
electron lasers, and laboratory spectrometers these characteristics are
generally sufficient for many x-ray absorption fine structure (XAFS), x-ray
emission spectroscopy (XES), and resonant inelastic x-ray scattering (RIXS)
applications in the chemical sciences. Unlike existing optics manufacturing
methods using epoxy or anodic bonding, vacuum forming without adhesive is
temporary in the sense that the bent wafer can be removed when vacuum is
released and exchanged for a different orientation wafer. Therefore, the
combination of an x-ray compatible vacuum-forming chamber, a library of thin
wafers, and a small number of forms having different secondary curvatures can
give extreme flexibility in spectrometer energy range. As proof of this method
we determine the energy resolution and reflectivity for several such
vacuum-formed bent crystal analyzers (VF-BCA) in laboratory based XAFS and XES
studies using a conventional x-ray tube. For completeness we also show x-ray
images collected on the detector plane to characterize the resulting focal
spots and optical aberrations.
