Measurement of the focal spot size of X-ray tubes with spot sizes down to 100 nm

New X-ray systems, using metrological computed tomography, can visually inspect manufactured component dimensions and integrity down to the nanometre-scale. Measurement performance depends on focal spot size, shape, and stability, but no standard method exists for spot sizes below 5 micrometres. As a result, equipment manufacturers apply different methods, and provide different results. A need for traceable measurement methods for determining focal spot characteristics of nanometre-resolution X-ray tubes was identified as a research priority by the CEN technical committee for non-destructive testing.

To enable resolution down to 50 nanometres, the project has developed new standard practices for characterising X-ray focal spots to higher levels of accuracy. The project developed procedures intended as part of CEN standard EN 12543, which may lead to amendments to standards applying to welding, casting, electronics, aerospace, and dimensional metrology.

The project will enable NMIs to provide traceable determinations of focal spot size and shape, to benefit industry through reduced failure rates, increased component lifetimes, and improved competitiveness of European manufacturing.