The monolithic X-ray polycapillary lens and its application in microbeam X-ray fluorescence

Abstract

A monolithic polycapillary X-ray lens is a single piece glass optic made in a furnace. It is composed of hundreds of thousands of individual capillaries. The X-ray lens can be used to collect divergent X-rays emitted from an X-ray source in a large solid angle and to transmit them with high efficiency by multiple total reflections in the individual capillaries, thus forming an intense focused beam. Recently, new monolithic focusing lenses have been manufactured, tested and used for microbeam X-ray fluorescence (MXRF) analysis in the authors' laboratory. For the Mo Kα line, the measured focal spot diameter was 30 µm. A gain factor of more than 2000 compared with when an aperture was used instead of the lens was obtained. The application of the lens in MXRF reduced the detection limits for transition elements down to the sub-pg level when a 1 W X-ray source was used.