X-ray Applications with Glass-Capillary Optics

Glass capillaries have unique properties for guiding X-rays in experiments with micrometer precision. Design considerations of such optics are presented for X-ray applications involving macromolecular crystallography, tomography and high-pressure experiments at the Cornell High Energy Synchrotron Source. The authors propose that crystallography with protein crystals is feasible on a 50 μm or smaller scale using capillary optics along with a cold gas stream and precision rotation stages. For computed tomography experiments, capillary optics can produce X-ray beams on a submicrometer scale. The distribution of X-rays passing through the sample can then be blown up in size with a secondary capillary optic to match the ~10 μm pixel size of CCD detectors. For high-pressure experiments in diamond-anvil cells, mono- and polycapillary optics may provide 1–50 μm diameter beams for diffraction or X-ray absorption fine-structure applications.