Abstract: A dual-layered optical disc for use with a pickup head has a first signal layer, a semitransparent film, a space layer, a reflective film, and a second signal layer, all of which are deposited one upon the other in this order. A plurality of first signal pits are formed on one side of the first signal layer confronting the semitransparent film, while a plurality of second signal pits are formed on one side of the second signal layer confronting the reflective film. The first signal layer has a thickness selected so that when a read laser beam emitted from the pickup head is incident on the first signal layer in a direction generally perpendicular thereto, the focus position where the read laser beam is best focused is positioned within the space layer, thereby substantially equalizing jitters of signals played back from the first and second signal pits.

Abstract: A method of making a multilayer optical disc of a type formed by laminating a plurality of signal layers each having a spiral or concentric pattern of a series of pits so that information can be read by irradiating any one of the signal layers with a playback laser from a surface of a substrate of the optical disc and reading waveforms reproduced therefrom. A master disc having a pit pattern formed thereon by exposing to a modulated exposure light pulse train is prepared for each of signal recorded layers. Based on this master disc, a mold is then prepared having a pit pattern which is a replica of the pit pattern on the master disc. Using the molds, respective replicas are formed and bonded together in face-to-face relation to thereby provide the multilayer optical disc.

Abstract: A method of producing a microscopic structure by anisotropic etching, in which ion etcing is conducted by irradiating an ion beam emitted by an ion source over a workpiece while a direction of progress of the ion etching is being changed.

Abstract: A reproducing method for the V-shape groove optical disk is disclosed in which three laser beams are irradiated on a disk, and the reflected laser beams are focused on three light receiving units through object lens. The laser beams irradiated on two light receiving units are used for reproducing signal. Each of the two light receiving units has a light receiving segment which receives a portion of the reflected light beam which is greater than a half of the total reflected light so that a quality of the reproduced signal is improved.

Abstract: In a plasma surface treating method, a sample to be treated is supported on a first electrode within a vacuum vessel and a second electrode is caused to confront the first electrode. Active species of negative ions are then generated by means of a direct current glow discharge produced in an abnormal glow discharge region and are subsequently impinged upon a surface of the sample to induce a chemical reaction with the sample.

Abstract: In a plasma surface treating method, a sample to be treated is supported on a first electrode within a vacuum vessel and a second electrode is caused to confront the first electrode. Active species of negative ions are then generated by means of a direct current glow discharge produced in an abnormal glow discharge region and are subsequently impinged upon a surface of the sample to induce a chemical reaction with the sample.

Abstract: An optical data medium is disclosed from which information recorded to the surface is reproduced by focusing a laser thereon and reading the light reflected from the data surface. The medium includes a first transparent layer having a top data surface for carrying data, and a second transparent layer having a bottom data surface for carrying data. A semi-transparent layer is inserted between the first and second transparent layers. When the laser is focused on the top data surface, the data carried therein is reproduced, and when the laser is focused on the bottom data surface, the data carried therein is reproduced.