Neutron reflectometry is a non-destructive structural analysis method utilizing optical property of neutron at interfaces between two media, and is indispensable for structural analysis on material interfaces due to high depth resolution of a sub-nm scale. The specular reflection of neutron at the interface can be described by the Shrodinger equation with the one-dimensional square well potential for a plane wave. Here, the principles of neutron reflectometry are explained using a typical few examples from a single ideal interface to a multi-layer system. Further, the removal of incoherent scattering background by using a polarized neutron beam is explained for hydrogenous materials.
