A test set of four metals was made. Three squares, lead (Pb), iron (Fe) and aluminium (Al), were each 125 µm thick. The fourth square, 87.5 µm of copper (Cu), was chosen to give a similar absorption contrast to the iron square.
Lead is, of course, much more dense than aluminium, and these two metals are easily identified from the absorption image, given that we know that their thicknesses are the same. Iron and copper cannot be distinguished from the absorption image, even knowing the thicknesses – the grey‑levels are the same. IBEX technology gives access to spectral information, and thus to the energy‑dependent absorption of the materials. In this way, the materials can be identified.
Click the arrows in the image pane to go through images illustrating this point.
The data were collected at 50 kV using a micro‑focus tungsten X‑ray tube and a CMOS flat‑panel detector.
See the Technology Note for further information.