FIB images show superior channeling contrast compared with conventional electron imaging. An example is given in the left image. Channeling contrast is created due to different ion–sample interactions in specific crystal directions. Ions penetrate deeper into materials in low index directions such as [110], [100]. In these directions, the collision cascade penetrates deeper into the material, due to there being a larger atomic distance (a wider gap) at these orientations, which leads to lower secondary electron yields. This means that these directions appear darker.

Ion channelling contrast image on TEM foil of Cu-Ni alloy. Image courtesy of Animesh Babak, Adelaide Microscopy