ASTM E 1165 - 92. Standard Test Method for Measurement of Focal Spots of Industrial X-Ray Tubes by Pinhole Imaging

American Society for Testing and Materials (ASTM). Reapproved 1996, 7 pages.
This test method provides instructions for determining the length and width dimensions of line focal spots in industrial X-ray tubes (see Note 1). This determination is based on the
measurement of an image of a focal spot that has been radiographically recorded with a pinhole projection/imaging technique.