X-ray mirror surfaces evaluated by an X-ray topographical technique

Abstract

Topographic images have been taken with 8 and 16 keV X-rays on a variety of X-ray reflecting surfaces, e.g. a platinum mirror, silicon carbide mirror, uncoated float glass, and on a Layered Synthetic Microstructure (LSM). A fine slit produces a monochromatic diffraction image from the Cornell Electron Storage Ring (CESR). This image is subsequently reflected from the desired substrate and recorded on photographic film. The reflected image reveals topographic information pertaining to the structure of the surface. In particular, the variance of the central peak from a straight line provides a measure of slope errors on the surface with the sensitivity of better than 1 arc second. Areas of concentrated scattering indicate regions of greater surface roughness. An advantage of this method is that the mirror quality can be evaluated with X-rays under conditions similar to those for designed operation.