Abstract: A primary recording medium simultaneously receives a pair of reference beams, one of which is comprised of rays that are parallel to an axis of rotation of the primary medium. The primary medium is incrementally rotated about the axis after each of a plurality of object beams is transmitted in sequence thereto from a fixedly disposed source. Interactions between the object beams and the reference beams are recorded in the primary medium as volume holograms, whereby a primary record is recorded. Reconstructions of the object beams and corresponding reference beams emanate from the primary record in response to a primary reconstructing beam. An interaction between the reconstructions is recorded as a volume hologram in a secondary recording medium whereby a secondary record is recorded. A reconstruction of a selected one of the object beams emanates from the secondary record in response to a secondary reconstructing beam.

Abstract: An optical recording medium comprises a light reflecting material coated with a light absorbing material which is coated with a transparent barrier layer and overcoated with a relatively thick transparent protective layer. During recording, portions of the light absorbing layer are ablated by a modulated focussed light beam, thereby exposing portions of the reflecting layer while leaving the barrier and overcoat layers intact. Information is recorded in the form of a reflective-antireflective pattern. The overcoat layer suspends dust particles far above the focal plane of the recording lens, thereby reducing their effect on the recording or playback signal. The barrier layer insulates the light absorbing layer and the overcoat layer from chemical and thermal interactions which might result in a decreased signal-to-noise ratio.

Abstract: The optical efficiency, with which a coupling portion of a fiber-optic can be coupled by evanescent fields to a planar optical waveguide through a phase-matching diffraction grating on the surface of the planar optical waveguide, is increased by deforming the coupling portion so that it is a negative replica of the undulating surface of the diffraction grating.

Abstract: Organic holographic recording media comprise organic photosensitive compounds such as .alpha.-diketones, quinones and nitro compounds in sucrose benzoate as host.

Abstract: Permanent thin-phase holograms are recorded wherein the recording medium contains a recording layer comprised of an olefinically unsaturated negative photoresist polymer containing an .alpha.-diketone.

Abstract: Holographic recording media which form permanent holograms with excellent recording sensitivity are prepared from .alpha.-diketones which are capable of intermolecular hydrogen atom abstraction dissolved in a transparent, cured vinyl benzene polyester polymerhost.

Abstract: The sensitivity of organic volume phase holographic recording media comprising an .alpha.-diketone in an acrylic polyester polymer can be improved by heating the recording media during or after recording.

Abstract: An ablative recording medium comprises a substrate coated with a light reflecting coating which in turn is coated with a light absorptive layer of 4-phenylazo-1-naphthylamine formed by evaporation of Sudan Black B dyestuff. During recording, portions of the organic coating are ablated, or vaporized, by a modulated focussed light beam, thereby exposing portions of the reflective layer and recording video information as a reflective-antireflective pattern.

Abstract: Organic volume phase holographic recording medium comprising an .alpha.-diketone in an acrylic polyester polymer is desensitized by exposing the medium to desensitizing light after recording is complete. This inactivates the .alpha.-diketone and prevents damage to the medium during readout.