Albert V. Baez

Formation of Optical Images by X-Rays

Several conceivable methods for the formation of optical images by x-rays are considered, and a method employing concave mirrors is adopted as the most promising. A concave spherical mirror receiving radiation at grazing incidence (a necessary arrangement with x-rays) images a point into a line in accordance with a focal length f=Ri/2 where R is the radius of curvature and i the grazing angle. The image is subject to an aberration such that a ray reflected at the periphery of the mirror misses the focal point of central rays by a distance given approximately by S=1.5Mr2/R, where M is the magnification of the image and r is the radius of the mirror face. The theoretically possible resolving power is such as to resolve point objects separated by about 70A, a limit which is independent of the wave-length used. Point images of points and therefore extended images of extended objects may be produced by causing the radiation to reflect from two concave mirrors in series. Sample results are presented.

A Study in Diffraction Microscopy with Special Reference to X-Rays

The factors which affect resolution in diffraction microscopy are studied. The inequality pλ>4nd/N is a necessary condition for making good holograms, where p is the distance between source and film, d is the diameter of the source, and λ is its wavelength, n is the number of recorded central bands of the diffraction pattern, and N is the resolving power of the film. The minimum theoretical resolvable distance between two point objects is limited by d and N but not by the wavelengths used in the analysis and reconstruction. Possible applications to the focusing of x-rays by Gabor techniques and by a single Fresnel zone plate are considered.