One of the most important characteristics of a microfocus X-ray source is its focal spot size and the resolution that can be achieved using a particular setup. X-RAY WorX introduces a whitepaper that summarizes all aspects of the procedure and gives a valuable guideline to perform accurate and repeatable focal spot measurements.

Focal spot sizes down to 5 microns can be analyzed using the common standard EN 12543-5 that was released in 1999. The recent ASTM 2903-13 is a derivative of the EN standard and may be chosen, too. To evaluate focal spot sizes below 5 microns, an indirect approach – the analysis of JIMA resolution - is chosen, since the accuracy of EN 12543-5 is very low in this range of spot sizes.

The well known and widely accepted JIMA resolution patterns allow the validation of the MTF (modulation transfer function) of several predefined line patterns to obtain a repeatable and realistic estimation of the focal spot size of a microfocus X-ray source.

The measurement of focal spot sizes requires reasonable experience with standards and X-ray technology like optimized operation of the source, calibration of the detector, the selection of the required magnification, and the use of advanced image processing software.

The whitepaper on focal spot measurement may be obtained on request from your X-RAY WorX representative

Setup of the tube, detector and JIMA test chart   Line profile across JIMA line pattern