FABRICATION ERRORS OF COMPUTER-GENERATED MULTILEVEL PHASE-HOLOGRAMS

Three typical error sources in fabrication of multilevel computer gene rated phase holograms are investigated. These are (i) misalignment of different mask levels (ii) phase errors caused by deviation of the etc hing depth and (iii) pattern errors due to overetching or undercutting . Analytic expressions for both the faulty transmission function and t he associated diffraction orders are given. The investigations are bas ed on the Fresnel/Kirchhoff approximation. Computer simulations are co mpared with experimental data. Different fabrication methods for multi level phase structures are analyzed.