Effect of Sample Thickness and Operating Voltage on the Contrast of Kossel Transmission Photographs

Abstract

The photographic contrast of transmission Kossel patterns is examined in terms of the voltage and thickness variables since other parameters in the contrast equation generally cannot be controlled by the investigator; they are fixed functions of the material. It is shown that there is no single thickness yielding optimum contrast. However, manipulation of the contrast equation yields an approximation to the thickness and operating voltage relationship giving Kossel transmission photographs of nearly optimum contrast. Methods for calculating this relationship for any crystal-radiation combination are described. It is assumed throughout that the crystal is not completely free of imperfections; however, neither is the crystal assumed to be completely mosaic.