  We investigate the effects of spin-momentum locking on the interference and
diffraction patterns due to a double- or single-slit in an electronic
\emph{Gedankenexperiment}. We show that the inclusion of the
spin-degree-of-freedom, when coupled to the motion direction of the carrier --
a typical situation that occurs in systems with spin-orbit interaction -- leads
to a modification of the interference and diffraction patterns that depend on
the geometrical parameters of the system.
