The heart of the Advanced X-ray Astrophysics Facility is the high resolution mirror assembly. In a conventional large astronomical telescope, gathered light is focused by a high angle of reflection. Higher energy X-rays directly striking even a highly reflective surface can easily pass through or be absorbed by most materials. To gather and focus X-rays AXAF uses a grazing incidence mirror assembly, a technology successfully pioneered in space by the Einstein Observatory, HEAO2.
This videos shows an artist concept of AXAF in space. It zooms in to show the mirror assembly. Then it shows a cross section of the grazing incidence mirror.