Computer simulation of x-ray diffraction topographs of stacking faults

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Abstract
A group of programs are described which will simulate a photograph of arbitrary contrast ratio or exposure. We have used these programs to simulate x‐ray topographs of stacking faults as described by Authier’s spherical wave treatment of a perfect crystal with a stacking fault. Intrinsic and extrinsic faults are examined with a range of different wavelengths, fault orientations, diffraction conditions, specimen thicknesses, and absorption coefficients. In cases where experimental topographs are available, they correspond closely to the simulations, thereby indicating the basic correctness of Authier’s theory. The simulations illustrate the separation of the complex diffraction pattern into three components. Only one component carries information on the nature of the fault. The simulations clearly delineate the conditions for identifying the fault type; namely, the critical value of μd for adequate visibility of the I3 fringes is in the range 1<μd<2. Traverse patterns are demonstrated to be an unreliable guide to the nature of the fault.