  Scattering of waves due to a vertical array of equally-spaced cracks on a
square lattice is studied. The convenience of Floquet periodicity reduces the
study to that of scattering of specific wave-mode from single crack in a
waveguide. The discrete Green's function, for the waveguide, is used to obtain
semi-analytical solution for scattering problem in case of finite cracks
whereas the limiting case of semi-infinite cracks is tackled by an application
of Wiener--Hopf technique. Reflectance and transmittance of such an array of
cracks, in terms of incident wave parameters, is analyzed. Potential
applications include construction of tunable atomic scale interfaces to control
energy transmission at different frequencies.
