Design of multiphase level holograms

The authors extend the design of a binary phase, non-separable computer generated hologram (CGH) design to a multiple, quantised phase level design. Although the encoding of increased phase levels is still realised using rectangular structures, it is envisaged that the multi-phase CGH would approach a continuous surface relief profile, thus reducing the number of high-order Fourier coefficients. The improvements of these designs in terms of efficiency and the fidelity of the fanout array are reported, together with a discussion of the trade-off between space bandwidth product and the number of quantised phase levels. Also reported are the interesting observations of phase dislocations, appearing in the surface relief profile