A study of 8.5 μm microchannel plate X-ray optics

We have investigated the X-ray focusing properties of microchannel plates (MCPs) with square channels of side length 8.5 μm. Both planar and spherically slumped MCPs (radius of curvature Rslump=0.5m) have been examined. We have observed foci of 7' deg. and 14' deg. FWHM, respectively. In addition, we have measured the 8 keV X-ray reflectivity of channel surfaces which have been subjected to a variety of chemical treatments. These reflectivities are found to correspond closely to theoretical values calculated by a simple two-layer model of the MCP reflecting surfaces. The inferred values of surface roughness for those MCPs thermally annealed at 430 deg. C is ∼11 A, about a factor of two better than previously measured. (author)