Design Of Holograms Research Articles

Iterative Approaches To Computer-Generated Holography

Two iterative algorithms for synthesis of binary computer-generated holograms (CGHs) for image reconstruction are described: alternating projections onto constraint sets (POCS) and direct binary search (DBS). Comparisons with conventional methods for CGH synthesis show that POCS and DBS yield substantially lower mean-squared reconstruction error and higher diffraction efficiency. The best method is DBS, but it is also the most computationally intensive. To ameliorate this disadvantage, an acceleration technique is presented for DBS. With this technique, the design of binary holograms with moderate space-bandwidth product becomes feasible. For example, the computation required to design a hologram with 256K elements is reduced by a factor of 121.

Dual-phase holograms: improved design

An analysis of dual-phase holograms is presented which concentrates on the effects of phase quantization on hologram design. Two different quantization schemes are investigated and used in conjunction with an iterative design algorithm to reduce quantization error. It is shown that performance of the quantization schemes depends on the number of quantization levels available.

Design considerations for holographic optical interconnects

The geometrical design characteristics of multiple-image holograms are evaluated. A figure of merit expressing these characteristics as a function of the hologram diameter and the distance between the hologram and the image plane is developed. This value is then used to compare two designs which are capable of forming several hundred interconnections. The results indicate that these connections can be formed between points on the substrate separated by 2-3 cm provided that the holograms are separated from the substrate plane by 0.5-1 cm. Each hologram design is experimentally demonstrated in bleached photographic emulsions.

Synthesis of digital holograms by direct binary search

A new approach to the design of computer-generated holograms makes optimal use of the available device resolution. An iterative search algorithm minimizes an error criterion by directly manipulating the binary hologram and observing the effect on the desired reconstruction. Several measures of error and efficiency useful in assessing the optimality of digital holograms are defined. Methods for designing digital holograms that are based on projections and error diffusion are presented as established techniques for comparison to direct binary search.