The X-Ray Microscope

Abstract

IN NATURE of April 22, 1939, I described an optical method of summing a double Fourier series, and so of producing an image of a crystal structure. To get a projection of the structure in a direction parallel to the b axis, for example, holes are drilled in a brass plate in the positions of cross-grating spectra. Each X-ray reflexion hol is represented by a hole the area of which is proportional to F (hol). When a parallel monochromatic beam passes through these holes, and then through a lens, the Fraunhofer fringes build up an image of the crystal structure which can be viewed through a microscope. Since a wide range of holes is required, arid they are one or two millimetres apart, the smallest holes must be very fine. I am indebted to Dr. E. W. Fish for supplying me with a series of minute drills.