A scanning helium ion microscope is an imaging technology based on a scanning helium ion beam. Similar to other focused ion beam techniques, it allows to combine milling and cutting of samples with their observation at sub-nanometer resolution.

In terms of imaging, HIM has several advantages over the traditional scanning electron microscope (SEM). Owing to the very high source brightness, it is possible to obtain qualitative data not achievable with conventional microscopes which use photons or electrons as the emitting source. As the helium ion beam interacts with the sample, it does not suffer from a large excitation volume, and hence provides sharp images with a large depth of field on a wide range of materials. Compared to a SEM, the secondary electron yield is quite high, allowing for imaging with low currents, and allow imaging without conductive coating. The detectors provide information-rich images which offer topographic, material, crystallographic, and electrical properties of the sample. In contrast to other ion beams, there is no discernible sample damage due to relatively light mass of the helium ion.