We recently had the opportunity to combine our 1 kW Excillum MetalJet E1+ X-ray source with a custom X-ray optic from AXO Dresden. This created a unique beam delivery system capable of focusing monochromatic 24 keV radiation into a bright spot of down to 13 µm diameter.
By being able to tune both the primary X-ray spot size of the source and control the divergence of the focused beam from the optic, spot sizes ranging from 13 µm to 20 µm could be generated with divergences ranging from 2 to 12.6 mrad. Quantitative measurements of such small X-ray spots are challenging, but by measuring the X-ray spot shape with an ultra-high-resolution detector with ~1 µm pixels from Rigaku Innovative Technologies Europe and absolute flux with a calibrated photo diode, we could carefully characterize the X-ray beam focal spots. The figure to the right, e.g., shows the resulting focal spot of a high flux setting with 1000 W source power at 160 kV focused into a 12.6 mrad convergence beam generating a flux of 1.8×107 photons/s into a 15 µm focal spot. As comparison, this is focused X-ray flux similar to what is typically achieved into a 100 µm spot size with a typical silver stationary-anode microfocus X-ray source.
To our knowledge, we have generated the brightest and smallest monochromatic high energy X-ray focal spots ever created by a conventional lab X-ray source, allowing to generating sample data in reasonable times even from minute samples. Furthermore, the beam delivery system has been used for real application work. More about the application and the data generated will be revealed in a later article.
Highlights of the MetalJet E1+ tight-focus beam delivery system:
- Monochromatic 24 keV X-rays
- Down to 13 µm X-ray spot size
- 2-15 mrad convergence angle (Slit controlled)
- Measured flux of ~1.8×107 ph/sec for 15 µm focal spot