A GRAZING INCIDENCE MICROSCOPE FOR X‐RAY IMAGING APPLICATIONS

One of the early approaches to x-ray microscopy was based on the imaging characteristics of axially symmetric conic surfaces. Hans Wolter’ showed that these surfaces, when used in pairs as grazing incidence mirrors, could produce good images over a useful field of view. Wolter’s ideas found their first applications in astronomical instrumentation, following the suggestion of Giacconi and Rossi: and x-ray telescopes have played an important role in stellar and solar x-ray observations for over a decade. The optics of these telescopes have diameters as large as half a meter and collecting areas of several hundred square centimeters. In recent years, there have been programs at several laboratories3-’ aimed at the development of small grazing incidence optics for x-ray imaging at finite conjugate distances. The motivation for these programs came from two perceived uses: as diagnostics of laser fusion plasmas and as relay optics at the image plane of an x-ray telescope. It is possible that applications in fields such as biology and materials science may also be found. This paper discusses an x-ray microscope with 10 X magnification, designed and built for the laser fusion program at Los Alamos Scientific Laboratory in Los Alamos, New Mexico. The microscope’s purpose is to image the soft x-ray emission from the laser-target interaction region over a field of view of hundreds of micrometers with high sensitivity and micrometer resolution. It has two reflecting surfaces: an ellipsoid and a confocal, coaxial hyperboloid. It was fabricated by conventional lapping and polishing guided by sensitive in-process metrology. The completed optics were tested in the laboratory with x-rays. The results of that evaluation show that the performance of the optics fulfills our expectations. The resolution, field of view, depth of focus, and sensitivity meet the design goals. In this paper, I shall present a brief description of the optics, the performance expected of them, the methods we used to test them, and the results of the tests.