Systems for forming improved reflection holograms with a single beam 



A hologram forming system for forming, from a single beam source and a reflective mirror, a reflective hologram in which spurious reflection and transmission hologram recordings are eliminated. Reflected rays are changed in phase relative to the primary beams during the recording period so that spurious holograms do not form. The remaining effect of the reflected rays is to slightly change the overall refractive index of a phase recording material (such as dichromated gelatin) with a resultant slight loss of available index of modulation or to slightly, uniformly, darken an amplitude hologram film, (such as silver halide) with a slight loss of available contrast. The invention includes hologram forming systems that move the cover plate relative to a fixed recording medium with and without a phase shifter in the primary beam and a hologram forming system that moves the substrate and mirror relative to the fixed cover plate. 

Holographic exposure system to reduce spurious hologram noise 



A method and apparatus of exposing a hologram to reduce spurious noise holograms. The exposure light source is moved relative to a recording module within predetermined distances that will ensure a blurring of the fringes of a noise hologram that is formed at a distance from a primary hologram while substantially not affecting the primary hologram. The controlled relative movement of the exposure source and the recording module within predetermined limits provide a considerable improvement in reducing the efficiency of spurious noise holograms. 

Multi-layer holographic notch filter 



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.