Integration of Diffractive Optics for Top-Hat Generation and En-hanced Depth of Focus

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 instructions as to what needs to be considered when combining the diffractive elements with focusing systems 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 propagation behavior in free space, a possible adjustment of Top-Hat size and the increase of the depth of field of a Gaussian laser beam.