Abstract: A rotating disc-shaped carrier upon which have been recorded audio, video or computer data in holographic form, a method for forming such a carrier, and an apparatus for reading such a carrier is disclosed. A beam of coherent radiation is spatially modulated in a prescribed way, this beam then illuminating one radial of a rotating carrier upon which has been recorded a series of holograms in the form of a spiral track or series of concentric tracks. The holograms are elongated in a direction perpendicular to movement of the rotating carrier and overlap in directions both parallel and perpendicular to such movement, the amount of overlap in the perpendicular direction being inversely proportional to the amount of overlap in the parallel direction such that data storage density remains constant across the surface of the rotating carrier. The sequentially illuminated holograms generate a series of signal images which vary in amplitude, width, spatial frequency, azimuth or position relative to a centerline.

Abstract: Using a buffered acid catalyst, a cross-linked urea-formaldehyde polymer matrix is formed by catalyzing an aqueous mixture of an urea-formaldehyde concentrate, urea-formaldehyde resin, and powdered urea. The resulting thermoset polymer which possesses, in part, a cyclic structure, is of unusual hardness and has utility, with or without fillers, as a molding or casting material possessing controllable shrinkage characteristics because of uniform molecular structure and formula versatility. The catalyst system may be used for the polymerization or cure of other urea-formaldehyde or polymeric condensation systems.

Abstract: A cross-linked urea-formaldehyde polymer matrix is formed by catalyzing, using a buffered acid as the catalyst, an aqueous mixture of a urea-formaldehyde concentrate, urea-formaldehyde resin, and powdered urea. The resulting thermoset polymer which possesses, in part, a cyclic structure, is of unusual hardness and has utility, with or without fillers, as a molding or casting material possessing controllable shrinkage characteristics because of uniform molecular structure and formula versatility.

Abstract: A rotating disc-shaped carrier upon which have been recorded audio, video or computer data in holographic form, a method for forming such a carrier, and an apparatus for reading such a carrier is disclosed. A beam of coherent radiation is spatially modulated in a prescribed way, this beam then illuminating one radial of a rotating carrier upon which has been recorded a series of holograms in the form of a spiral track or series of concentric tracks. The holograms are elongated in a direction perpendicular to movement of the rotating carrier and overlap in directions both parallel and perpendicular to such movement, the amount of overlap in the perpendicular direction being inversely proportional to the amount of overlap in the parallel direction such that data storage density remains constant across the surface of the rotating carrier. The sequentially illuminated holograms generate a series of signal images which vary in amplitude, width, spatial frequency, azimuth or position relative to a centerline.

Abstract: A compact portable pocket brush has retractable bristles arrayed in groups attached to a plurality of bristle group holders or supports mounted upon pivot pins in a brush case. The top wall of the case has a plurality of downwardly sloping apertures respectively located in alignment with each bristle group in the brush. The bristle group pivot pins are pivotably mounted upon a slide in the bottom of the case. When the slide is moved between two positions, each bristle group is pivoted between a retracted position in which it is enclosed within the case and an erect position wherein the bristles extend through the openings in the top wall of the case. When in the erect position all of the bristle groups are locked in a rigid vertical position by the engagement between the periphery of the holes and a portion of the bristle group holder so that the brushes can be used.