Semitransparent monochromators for X-ray imaging based on highly oriented pyrolytic graphite (HOPG)

Semitransparent HOPG monochromators are being investigated with an emphasis on their potential applications in X-ray imaging systems. HOPG plates and films, 5-100micrometers thick and up to 14 cm 2 in area, were tested. Scanning techniques were used to measure the profiles of local reflectivity and transparency at different monochromator thicknesses. Mosaic spread, (Delta) (omega) , down to 3.6' was recorded. HOPG film areas with average (Delta) (omega) =5' and 6' were equivalent to 4.5 and 10 cm 2 respectively. The echelon monochromator arrangement produced a sharp increase in reflectivity leading to the possibility of primary beam sweeping. Results to date are very promising for future applications in fields such as medical diagnostics and surgical treatments monitored using digital X-ray cameras.