Yaakov Amitai

Visor-display design based on planar holographic optics.

A method for designing and recording visor displays based on planar holographic optics is presented. This method can deal with the problem of recording-readout wavelength shift. The display system is composed of two holographic optical elements that are recorded on the same substrate. One element collimates the waves from each data point in the display into a plane wave that is trapped inside the substrate by total internal reflection. The other diffracts the plane waves into the eye of an observer. Because the chromatic dispersion of the first element can be corrected by the dispersion of the second, this configuration is relatively insensitive to source wavelength shifts. The method is illustrated by the design, recording, and testing of a compact holographic doublet visor display. The recording was at a wavelength of 458 nm, and readout was at 633 nm. The results indicate that diffraction-limited performance and relatively low chromatic dispersion over a wide field of view can be obtained.

Compact beam expander with linear gratings

Novel compact beam expanders that could be useful for applications such as providing light to flat panel displays are presented. They are based on a planar configuration in which three spatially linear gratings are recorded on one transparent substrate, so as to expand a narrow incoming beam in two dimensions. We present the design and recording procedures along with results, showing a relatively uniform intensity of the wide output beam. Such expanders can serve for illuminating flat panel displays.

Comparison of system size for some optical interconnection architectures and the folded multi-facet architecture

Abstract We compare system sizes for some optical interconnection architectures and introduce the folded multi-facet architecture which can potentially approach the smallest possible system size of any two-dimensional optical architecture.

Design of substrate-mode holographic interconnects with different recording and readout wavelengths.

A method for recording a substrate-mode holographic interconnect system, composed of two identical holographic optical elements (HOEs) which were recorded on the same plate, has been developed. Since the possible recording wavelengths for efficient holograms are usually different from the readout wavelengths, the holographic elements must be recorded with predistorted wavefronts to assure high diffraction efficiencies and low aberrations. The predistorted wavefronts are derived from simple spherical holograms whose readout geometries differ from those used during recording. The method is illustrated with HOEs recorded at 488 nm and read out at 633 nm. Nearly diffraction-limited imaging and high efficiencies were achieved.

Compact holographic beam expander.

A compact planar beam expander, composed of two holographic lenses that are recorded on a signal holographic plate, is presented. The smaller lens converts a narrow input beam into a diverging spherical wave at a high offaxis angle. This wave propagates toward the second lens, undergoing total internal reflections within the plate, and emerges from the larger lens as a magnified plane wave. One such expander, having a magnification of 3.5, was designed and recorded. The design and the recording procedure, along with the experimental results, are given.

Designing holographic lenses with different recording and readout wavelengths

A method for designing and recording transmission holographic lenses, having low aberrations and high diffraction efficiencies, in the presence of a recording–readout wavelength shift, is presented. The method is based on a recursive design technique, in which the final hologram is recorded with complex wave fronts that are derived from intermediate holograms. The design is illustrated for a lens with an f-number of 2.5 and a large offset angle, recorded at 488 nm and read out at 633 nm. A nearly diffraction-limited spot size and an efficiency of >80% are measured.

Holographic elements with high efficiency and low aberrations for helmet displays.

A recursive design technique for forming holographic elements which can be incorporated into helmet displays has been developed. To ensure that the holographic elements have low aberrations and high diffraction efficiency they must be recorded with complex wavefronts. These wavefronts are derived from relatively simple intermediate holograms whose readout geometry and wavelength differ from those during recording. The overall recursive design technique is illustrated for a single holographic helmet display element having resolution of less than 0.8 mrad and diffraction efficiency of more than 80 percent over a field of view of 16 degrees x 16 degrees .

Design of wavelength-division multiplexing/demultiplexing using substrate-mode holographic elements

Abstract A method for designing and recording a very compact wavelength-division multiplexing/demultiplexing system, based on substrate-mode holographic elements, is presented. The method is illustrated experimentally with a two channel system having high diffraction efficiencies, negligible cross-talk between the channels, and nearly diffraction limited imaging.

A three-dimensional optical interconnection architecture with minimal growth rate of system size

Abstract We present a three-dimensional optical interconnection architecture that can potentially approach the least possible system size of any architecture within a numerical factor of the order of ∼ 10. This architecture can provide an arbitrary pattern of connections among a three-dimensional array of points.

Fourier transformation with a planar holographic doublet.

The use of a single off-axis holographic lens for Fourier transformation results in phase errors that degrade its performance. A configuration of two identical off-axis holographic elements is proposed for performing Fourier transformation without phase errors. Such a configuration can be readily folded to form a compact and cascadable element that can be conveniently incorporated into optical correlators. The grating functions of the holographic elements needed for performing the desired transformation were used to record the planar configuration, which was then experimentally evaluated. The results reveal that phase errors were indeed eliminated, in close agreement with the calculations.