Abstract: An optical waveguide recording medium including an optical waveguide having a photocoupler for receiving a light beam, and a plurality of refractive index-discontinuous portions aligned on the optical waveguide. One of the refractive index-discontinuous portions includes a diffraction grating having grooves extending approximately perpendicular to the lengthwise direction of the optical waveguide at equal intervals which gradually become narrower or wider as the distance of that refractive index-discontinuous portion from the photocoupler increases. This recording medium ensures that information is recorded with high density.

Abstract: A three-dimensional optical recording medium is made of a photo-induced refractive index-changing material or two-photons absorbing material, which is based on photo-dissociation or photopolymerization. An optical information recording apparatus comprises a device for loading a three dimensional recording medium; a device for generating a high coherent optical pulse or a train of partially-coherent optical waves; a device for splitting the optical pulse into two pulse components and causing the two pulse components to propagate in the recording medium from opposite directions to meet at a predetermined three-dimensional position; a device for converging a light beam in the recording medium into a parallel beam; and a device for discretely scanning the meeting position of the pulse components to ensure three-dimensional recording in accordance with information to be recorded.

Abstract: Disclosed is an optical waveguide recording medium playing apparatus which has a heterodyne detection optical system and uses a waveguide light delaying/reflecting device for a reference light generating optical system. This waveguide light delaying/reflecting device is provided with a transducer which is disposed in close proximity of an optical waveguide where light is guided and which generates a surface elastic wave, so that the surface elastic wave may propagate in the light propagating direction of the optical waveguide. A laser beam is guided on the otpical waveguide, and a high-frequency drive current modulated in a burst form is applied to an electrode to generate a surface elastic wave, thereby accomplishing the shifting and phase delay of the light frequency of the reference light which ensures information reproduction with the interaction with the laser beam and the surface elastic wave. This optical waveguide is formed by diffusing Ti, Rb or the like on a substrate of GaAs, SiO.sub.2, or TeO.sub.

Abstract: A disk manufacturing apparatus produces a master disk of optical disks with a high recording density in a short time. According to one aspect, the apparatus comprises a housing forming a vacuum space; a holder holding a master disk having a recording surface subjected to an electron beam resist application process in the housing; a plurality of cold-cathode emitter elements, arranged two-dimensionally within a plane of beam irradiation to the master disk, irradiating an electron beam toward the master disk of optical disks when driven; and a driver selectively driving the a plurality of cold-cathode emitter elements. According to another aspect, the apparatus comprises at least one cold-cathode emitter element irradiating an electron beam toward the master disk when driven; a magnetic field lens, disposed between the cold-cathode emitter element and the master disk, focusing the electron beam emanated from the cold-cathode emitter elements.

Abstract: Disclosed is an optical waveguide recording medium playing apparatus which is characterized in that, in an optical system for reading and reproducing recorded information from an optical waveguide recording medium, an optical frequency modulating element for modulating light emitted from a super luminescent diode (SLD) as a light source is provided between the SLD and an objective lens for converging light on the photocoupler of the optical waveguide recording medium. The optical frequency modulating element comprises an ultrasonic light modulating element and a slit. The optical frequency modulating element drives the ultrasonic light modulating element with a frequency-modulated drive voltage to diffract the light from the SLD and limits the spatial spectrum of the diffracted light by means of the slit. Part of the diffracted light passes through the slit.

Abstract: A method of producing a diaphragm of an acoustic instrument having the steps of blending powders of carbon such as graphite, carbon black or the like and a thermoplastic or a thermosetting resin, shaping the resultant blend into a desired form and then carbonizing the shaped blend. As a result, it has become possible to produce a diaphragm of an acoustic instrument, having a light weight, high rigidity and a large ratio of Young's modulus to density.