Enhanced slit methodology for characterization of x‐ray focal properties

Abstract

The measurement of focal spot sizes in industrial x‐ray tubes using conventional edge and slit methods typically requires complex slit diaphragms and auxiliary testing equipment. Additionally, stringent spatial‐positioning requirements are imposed on the x‐ray tube, auxiliary testing equipment, and detector, making the machining of auxiliary testing equipment and meeting test conditions challenging. This study optimized and improved the auxiliary testing equipment and computations in the slit method based on the principles of the edge method. An experimental setup capable of self‐calibrating the spatial positions was designed, avoiding measurement errors during focal‐spot‐size measurements. We derived a formula for the focal spot size for this experimental setup, allowing measurements using slits of various sizes. Furthermore, we proposed a method for determining the focal spot size through linear fitting of multiple sets of slit dimensions and projected widths of the focal spot on the detector. This approach filters out random noise and errors during data collection, significantly enhancing measurement precision. By adjusting the slit and detector angles, we could measure the focal spot sizes at various angles and draw contour maps of the focal spot shape. This method was applied to measure the focal spot size and shape of a side‐window x‐ray tube under different voltage conditions. The overall measurement error was less than 6%, reflecting the reliability, accuracy, and consistency of the results obtained using the proposed method. Thus, the proposed method supports the inspection, verification, and maintenance of x‐ray sources.