The surface of a 12degrees vicinal Cu(111) crystal is formed by a regular distribution of (111) terraces, giving rise to a well-ordered step superlattice. Angle-resolved photoemission experiments show that the modulation plane of the Cu(111) surface state is the optical mean surface. The surface state is observed at the edge of the surface Brillouin zone, regularly repeated with the superlattice periodicity. The intensity distribution of the surface state in the reciprocal space has been probed using different photon energies. The results can be well understood on the basis of a simple diffraction-like model involving the bulk band properties. (C) 2003 American Vacuum Society.