Guiding and concentrating hard x-rays by using a flexible hollow-core tapered glass fiber

A 1.6-m-long, flexible, hollow glass fiber with a gradually diminishing bore diameter has been used efficiently to compress the size of an x-ray beam as it reflects from the inside walls of the fiber by total external reflection. The transmission characteristics of the fiber are reported for monochromatic synchrotron radiation of 8.04, 13, and 20 keV, as well as for CuKalpha radiation from a conventional x-ray tube. Intensity enhancements as large as 10 that correspond to a transmission efficiency of 54% were observed. The high efficiency of this prototype fiber supports the idea that this confinement technique should yield intensity gains of many orders of magnitude as the optimal fiber design is achieved.