Diffractive optics can be used to generate Top-Hat profiles in the working plane. In addition, there are theoretical considerations to use such concepts to increase the depth of field of a Gaussian laser beam. Within the scope of this work, we show the theoretical propagation behavior through free space behind a diffractive optic and relate characteristic propagation effects to the Rayleigh length zr of the initial beam used. It will be shown that Top-Hat profiles can be generated without any focusing power. From the knowledge gained from theoretical free space propagation calculation, we derive instruc-tions as to what needs to be considered when combining the diffractive elements with focusing sys-tems to realize an increased depth of field and how the size of Top-Hat profiles behind a focusing optic can be influenced. Furthermore, experiments results will be presented that demonstrate the prop-agation behavior in free space, a possible adjustment of Top-Hat size and the increase of the depth of field of a Gaussian laser beam.