Attenuation-contrast imaging is the conventional way of obtaining X-ray images. Materials with higher density or higher atomic number attenuate more X-rays, and therefore give less transmission.
Direct imaging of the transmitted intensity resembles a shadow of the object and is therefore referred to as shadow projection imaging. This method is widely used for medical imaging, but also for many other imaging tasks.
The technology development towards fast high-resolution imaging has been driven by the needs in scientific research, industrial R&D, and production quality control. To visualize fine details of the microstructure in the object, the imaging can be done either by using X-ray radiation coming from a small emission spot, or by using X-ray optics to build a microscope setup.
An X-ray tube with extremely small emission spot size can give high resolution imaging without optics. The advantages of this approach without optics, is the efficiency across the full energy spectrum as well as the ease in getting a large field of view. Thanks to the geometric magnification produced by the point source, the object can be imaged at much higher resolution than the detector can handle.
With a minimal emission spot size below 400 nm, the Excillum NanoTube N2 enables lensless sub-micron X-ray microscopy and NanoCT in the laboratory. For the applications where a 5-20 µm spot is enough, the MetalJet offers up to 10 times more brightness than any other microfocus tube.
High resolution imaging can sometimes require very long acquisition times. During the acquisition, high stability is necessary in all parts of the imaging system. The source emission spot stability is critical, in terms of spot size change and positional drift, since it may cause image blurring or require additional efforts in image processing. The new NanoTube N2 60 kV achieves an increase in flux by more than 3 times compared to its predecessor, the NanoTube N1, while maintaining the same sharp focus (the new NanoTube N2 110 kV enables higher penetrating power and even higher imaging speed). Thus, reducing the measurement time significantly. At the same time, the signal-to-noise ratio gives even higher image quality due to the reduced possibility of sample motion/environmental instability within the shorter CT measurement.
