Investigation of large null-CGH realization

For testing of aspheric surfaces, null-CGH were needed in different sizes and numerical apertures. The design of the CGH pattern from the wave front to be produced leads to physical problems and last not least to writing times that can strongly influence the price of the CGH. Due to this problems, we investigated the validity of the thin element approximation (TEA) that is the most usual and most convenient method for CGH pattern design. By using rigorous results for the change of the wave front to be constructed, it is possible to use TEA in an extended range. The investigation of the pattern decomposition has shown its influence on the data volume and writing time as well on the CGH quality. Using this knowledge, CGHs having up to 130mm diameter and numerical apertures of 0.55 have been fabricated.