The neutrons that aren't absorbed by the object hit scintillation targets where induced nuclear fission of lithium-6 can be detected and be used to produce an image.
Neutrons have no electric charge, enabling them to penetrate substances to gain information about structure that is not accessible through other forms of microscopy.
[1] Neutron-based instruments have the ability to probe inside metal objects — such as fuel cells, batteries and engines to study their internal structure.
[1] Glass lenses and conventional mirrors are useless for working with neutrons, because they pass through such materials without refraction or reflection.
The critical angle for grazing reflection is large enough (a few tenths of a degree for thermal neutrons) that a curved mirror can be used.
When a thermal neutron is absorbed by a lithium-6 nucleus, it causes a fission reaction that produces helium, tritium and energy.
These fission products cause the ZnS phosphor to light up, producing an optical image for capture by the CCD array.