Development of hard X-ray optics

Studies of cosmic X-ray sources have suffered from lack of focussing optics in the hard X-ray spectral region (E above 10 keV); in the absence of imaging optics, celestial X-rays are masked by the cosmic ray background, which severely degrades the detector sensitivity. There are several possible ways to develop grazing incidence imaging optics for this spectral region; we describe here one approach which utilizes numerous large diameter silicon wafers to form a flat-plate imaging telescope. A prototype imager of this type has been constructed, and we present measurements of surface quality, coalignment accuracy, and imaging ability.