An efficient method of implementing near-field diffraction in computer-generated hologram design

A new method is introduced for representing near-field scalar diffraction in the context of computer-generated hologram design. This method is computationally efficient and allows existing design algorithms for Fraunhofer holograms to be adapted to the design of near-field holograms. Results of applying this method to the simulated annealing algorithm are shown, along with a discussion of design and performance considerations peculiar to the near field. In particular, we have found near-field holograms to be less efficient and to form images of poorer quality than Fraunhofer holograms designed with the same underlying algorithm. Our studies suggest this may be an inherent difficulty in near-field hologram design.