Abstract: A recording medium has a first fringe pattern which is described by a first spectral bandwidth and a first image blur factor. The recording medium also has a second fringe pattern which is described by a second spectral bandwidth and a second image blur factor, the first spectral bandwidth being different from the second spectral bandwidth, and the first image blur factor being substantially equal to the second image blur factor. By providing multiple holograms in the single recording medium, the spectral bandwidths of each hologram are combined to provide an overall spectral bandwidth. Since the image blur factors of each hologram are substantially the same, i.e., overlap, when the two holograms are combined, the overall image blur factor is not increased. Indeed, it decreases at the same time the thickness of the recording medium is increased by a factor which is equivalent to the number of exposure in the single recording medium.

Abstract: A method is provided for reconstructing an image transmitted through a thick distorting medium. A remote source provides coherent light at the object plane, and a local source, typically derived from the remote source, provides corresponding light that is coherent with respect to the remote source. Light from the remote source is directed through the thick aberrator and into a holographic medium, such as a photorefractive crystal, to interact with corresponding light from the local source and produce a volume hologram. An angularly multiplexed volume hologram, which covers the entire object field, is written into the holographic medium by successive exposures of light from the remote and local sources for successive pixels of the object plane. Light from an object, which comprises two-dimensional information from the object plane, can be reconstructed by the volume hologram after being distorted by the thick aberrator.

Abstract: A display system is disclosed which employs multiple holographic elements for selectively reflecting images from separate projectors to one or more distinct viewing volumes. The display system provides the capability to project differing perspective images to individual crew members located at separated positions within a training simulator.

Abstract: A hologram that diffracts playback illumination over a wide angular range made pursuant to a technique that includes the steps of first exposing a volume hologram recording medium to record a first image which upon playback will diffract light over a first angular coverage, and then exposing the volume hologram recording medium to record a second image which upon playback will diffract light over a second angular coverage.

Abstract: A holographic member for a helmet visor comprising a first holographic layer having planes of diffraction oriented in a first direction in a given local area is disclosed. A second holographic layer disposed over said first holographic layer has planes of diffraction oriented in said local area in the opposite direction. The first holographic layer is transferred from a slanted planar holographic mirror. The second holographic layer comprises the holographic analog of an oppositely slanted transferred planar mirror. The slant and the opposite slant have substantially the same magnitude of slant but opposite orientation, providing for diffractive ghost compensation. A third holographic layer, unslanted, is transferred from an unslanted planar holographic mirror. The three holographic layers provide practical total eye coverage with minimum diffractive unwanted ghosts.

Abstract: A control arrangement for a galvanometer driven mirror whereby the angle of incidence of a beam on a holographic recording material is controlled includes a laser source and associated detector. The detector responds to a reflected position sensing beam incident thereon to generate electric currents. A ratio network forms the ratio of the sum and difference of the currents to generate an actual mirror position signal that is independent of the power output of the source of the sensing beam. An integrator is responsive to the error between the signal representative of the actual mirror position and a reference signal representative of a predetermined position of the mirror for forming a galvanometer position signal.

Abstract: An optical source comprises (a) a laser light source for emitting light in a light path; and (b) at least one holographic optical element disposed in the light path; wherein the laser light source and the holographic optical element are integrated into a monolithic strucuture. The holographic optical element collimates emitted light, circularizes emitted light, compensates for optical source wavelength shifts, launches the emitted light so that it is efficiently coupled to an optical fiber, and/or isolates the laser light source from interfering reflected light. Since the optical source is disposed in a single monolithic structure and a discrete holographic optical element may perform five distinct functions, the optical sources are compact, commercially versatile and easy to handle.