Abstract <p>In this paper, we consider the beam diffraction on quantized non-paraxial optical elements. We show that the formation of diffraction orders depends on both the numerical aperture and the focal length. In non-paraxial propagation, the main energy falls on the first diffraction orders, and it is also possible to eliminate a larger number of orders compared to the paraxial case. To simultaneously increase the number of longitudinal and transverse orders in the non-paraxial region, we propose using multifocal lenses as focusing elements. We expect that the results obtained can be used in (de-)multiplexing and signal detection problems.</p>