Accurate x-ray source dimension measurement by the spherically bent crystal imaging system

Abstract

X-ray sources are widely used in non-destructive testing applications. The focal spot shape and size of an X-ray source are important factors that influence the resolution and contrast of images. A monochromatic imaging method using a spherically bent crystal is proposed to measure the focal spot size of X-ray sources. The natural emission spectral lines of the target material are imaged to distinguish the target from the substrate. Thus, the fine structures of the focal spot can be measured combined with high spatial resolution. With a backlight imaging experiment, the imaging system achieves a high spatial resolution of ~10 μm over a large field of view of 2.5 mm with a narrow energy band of 2 eV at 8.05 keV. The X-ray focal spot size of a laboratory X-ray source with a Cu anode is measured using the spherically bent crystal imaging system and a pinhole camera respectively. The spherically bent crystal imaging system provides high spatial resolution and additional details for the focal spot. Thus, the monochromatic imaging method is applicable for the accurate X-ray source dimension measurement.