Three principle issues in computer-generated hologram (CGH) design are (1) the data that constitute the hologram, (2) the coding used to construct the hologram from the data, and (3) the technology used to fabricate the hologram. Fabrication technology influences both the nature (data) and form (coding) of the hologram and ranges from high space-bandwidth photoresist holograms exposed using c-beam milled binary masks to conventional photo-reproduced images of gray-scale and binary holograms and, finally, to optically- and electronically-addressable spatial-light modulators (SLMs). The design of binary amplitude Fourier holograms for display on a magneto-optic SLM (MOSLM) is considered in this work. The binary nature of the device provides two options for coding, either cell-oriented coding or point-oriented coding. Point-oriented coding is discussed herein; the MOSLM display of cell-oriented holograms has been reported [1]. Further, techniques that have been developed for generating point-oriented binary amplitude Fourier hologram data include a direct binary search (DBS) technique [2] and an iterative Fourier transform {3,4] technique. The iterative technique is discussed herein as a means for designing high diffraction efficiency holograms. The MOSLM display of DBS designed holograms has also been reported [2].

Aholographic combiner performing as a transmission combiner, consisting of two reflection holograms sandwiched together, has been developed for display applications which may benefit in packaging and/or performance due to the transmission geometry. The SRH combiner benefits from the reflection holographic components to reduce the spectral bandwidth to less than 20 nm. Predicted performance of the SRH versus simple transmission holograms, experimental data on the SRH, and practical display applications are presented.

Consider the whole class of holographic optical elements which either contain pictorial image information or have the ability to modify wavefronts. Even after many years of development, there are pitifully few marketable applications. The visionary promises that holography would create a revolution in the optics and display industries have not been fulfilled. Time has shown that, while it was relatively simple to dream up ideas for myriad applications, these ideas have generally not moved beyond laboratory demonstrations. Exceptions are a few items such as optical elements for supermarket scanners, head-up displays and laser diode lenses. This paper addresses: 1. The many promises of holographic elements 2. The difficulties of practical implementation 3. A reassessment of research and development priorities To give simple examples of these points, they are discussed mainly as they apply to one type of holographic application: automotive displays. These familiar displays give a clear example of both the promises and difficulties that holographic elements present in the world of high volume, low-costproduction. Automotive displays could be considered as a trivial application alongside more interesting fundamental research programs or high cost, sophisticated military applications. One might even consider "trivial" automotive displays to be a disreputable subject for serious researchers. The case is made that exactly the opposite is true. The resources for large scale development exist only in a healthy commercial market. An example is the Japanese funding of high technology through commercial product development. This has been shown to be effective in the development of other technologies, such as ceramics, semiconductors, solar cells and composite materials. In like manner, if holography is to become an economically important technology, more and more competent researchers must start looking outside the universities and military laboratories for support. They must involve themselves in some of the "trivial" commercial applications.

It is becoming more common to include HOE's in an optical system. This imposes some important problems for optical designers. In this paper, we will mainly discuss analyses and evaluations of an optical system which contains general HOE's and only describe briefly the generation of the HOE. A general HOE can be defined as a hologram whose object beam can assume any arbitrary wavefront. The general approach, by all known commercial softwares, is to model the required hologram being formed with simple spherical waves. The wavefront of the object wave is then modified by a phase function represented by a high order polynomials. The coefficients are then optimize to achieve the required results. This is adequate for most applications. If the required hologram does not resemble simple spherical waves nor has the symmetry, a large number of terms may be needed for an accurate representation. Our approach is to use exact ray-tracing to represent a general hologram. This was carried out with a commercial software, Super-Oslo, which, by the way, has not yet incorporated the phase modification feature. Since the Super Oslo can accommodate multiple configurations and also since it has the Star Command Language (SCL), we can either use a separate configuration or dynamically change the main configuration to define the hologram. The hologram itself is a user defined surface for which you can write your own program. Therefore the definition of the hologram can include any optical surfaces which can be handled by the software. The hologram can also be on any surface as long as you can write the program for it. The system design, analysis and evaluation can then be run by the SCL. We will use the Holographic Optical Head (HOH) as our example. The HOH includes two spherical lenses and two holograms.

We demonstrate two-dimensional optical wide angle beam steering by incorporating two steering techniques in tandem. The first technique is translation of two microlens arrays configured as a telescope array. The microlens translation produces wide angle steering to discrete angles. The second technique is optical phased array steering using a nematic liquid crystal array, which provides access to a continuous range of angles. By translating both microlens arrays of the 10 x 10 telescope array, we demonstrate steering to maintaining a peak irradiance within 3.6 dB of the on-axis peak irradiance.

Methods for designing substrate-mode holographic (SMH) optical elements are discussed in detail. These include techniques which account for the thickness change of a volume material during processing, and construction and reconstruction at different wavelengths. A method to reduce the angular sensitivity of these elements is also presented. Experimental results for components formed in dichromated gelatin with diffraction efficiency exceeding 95% and a FWHM (full angular width of the efficiency at half maximum) of more than 5° are given. Results for cascaded grating pairs are also discussed.