This scanning electron micrograph shows a single fiber approximately 0.5-mm wide. Borosilicate glass is similar to the material used to clad visible and IR optical fibers. The variance of the internal walls has to be controlled to within 10s of angstroms, which excludes the use of most metal with conventional manufacturing techniques. Other considerations enforced by the small critical angles and the desire to capture as much of the radiation as possible is the fiber's internal diameter. Multifiber components are mainly used for collimating diverse x-ray sources.
External screens hold the fibers with their hundreds of channels.
Internal diameters stay constant in this configuration, although they can be bent to 'focus' the photons as dictated by the application. The monolithic devices are smaller. Comprised of fibers fused together, these lenses do not require the screen external structure. Although these optics hold promise for imaging applications, current uses are limited to spectroscopic, diffraction measurement and other applications in semiconductor wafer inspection and other research and development areas, according to Gibson. MacDonald is developing the ground work for capillary lenses that will increase the contrast of mammograms and other clinical x-ray imaging applications because of their inherent filtering capabilities 1 .