Abstract: The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 .mu.m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

Abstract: The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 .mu.m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

Abstract: An optical medium comprises an information layer interposed between first and second transparent plates having about the same thicknesses. A light beam illuminates the information layer from a front side, or from a back side of the medium when the medium is inserted erroneously. Information is reproduced or recorded when the light beam illuminates the front side thereof. The information layer comprises a second area for recording a data pattern on which a direction of data arrangement can be easily determined, and a first area for recording main information. In order to determine which side of the disk is facing an optical head, the data pattern in the second area is reproduced, and the side can be determined according to a difference in direction of data arrangement in reproduced signals.

Abstract: The disk-shaped optical information medium of this invention includes: a first substrate having a center hole; a second substrate having a center hole; and a radiation curable resin interposed between the first and second substrates for bonding together the first and second substrates, wherein the optical information medium further includes a stopper for preventing the radiation curable resin from protruding into the center holes of the substrates, and a space between the first and second substrates of at least a half of a clamp region for clamping the optical information medium is filled with the resin.

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.

Abstract: In reproduction of signal recorded on an optical disk by irradiation of laser light beam thereon, interference between reflected diffracted light of +1th order or -1th order and reflected diffracted light of 0th order is coersively induced, and by detecting the interference light, a high frequency signal can be reproduced.

Abstract: A method of reproducing signals formed in slant surfaces of a V-shaped track groove formed in an optical disk. The beam reflected from each slant surface has a portion having a small crosstalk component and a portion having a large crosstalk component, the portions existing separately. The beam reflected from the V-shaped track groove is detected by a photodetector which is composed of two photodetector units. Thus, the output from the first photodetector unit has a small crosstalk component, while the output from the second photodetector unit has a large crosstalk component. The reproduced signal is obtained by subtracting, from a signal formed by amplifying the output of the first photodetector unit, a signal formed by amplifying the output of the second photodetector unit, so that the crosstalk component in the signal from the first photodetector unit is negated by the crosstalk component in the signal from the second photodetector unit, so that the reproduced signal can have a reduced crosstalk component.

Abstract: An optical disk and a method of recording, reproducing or erasing information on the disk by using laser beams. The optical disk is provided thereon with grooves each having a V-shaped groove in the radial directioin. At least two laser beams are focused on two adjoining slants of each V-shaped groove so that these two slants are used concurrently for high-density recording reproducing or erasing of high-quality information.

Abstract: An optical disk reproducing apparatus of the type in which a tracking control is performed by projecting a controlling laser beam to the center of each of a plurality of V grooves formed on an optical disk and using far-field images of light beams reflected from the optical disk and the signals recorded on the adjacent slopes of the V groove are read by respectively projecting two reproducing laser beams to the slopes. To remove the low-frequency components of the signals on the slopes entering a tracking error signal, the low-frequency components are extracted from the two reproduced signals by low-pass filters and the difference therebetween is generated as a correction signal which in turn is subtracted from the tracking error signal, thereby improving the accuracy of the tracking control.

Abstract: An optical disk and a method of recording, reproducing or erasing information on the disk by using laser beams. The optical disk is provided thereon with grooves each having a V-shaped groove in the radial direction. At least two laser beams are focused on two adjoining slants of each V-shaped groove so that these two slants are used concurrently for high-density recording reproducing or erasing of high-quality information.

Abstract: An optical disk having V-shaped grooves with depths periodically varied at a frequency f for every two grooves, thus realizing a large recording area on each slant of the grooves. A tracking method for the optical disk in which two laser spots irradiate two adjoining slants of a V-shape groove, and pilot signals are made of components of the frequency f which are detected from the reflected beams of the respective two laser spots on the optical disk, and whereby the tracking is performed by controlling so as to make the magnitudes of the two pilot signals become equal to each other.

Abstract: In an optical disk having grooves, pits representing reference signals in header regions of the grooves are disposed to be spaced apart from each other in a longitudinal direction of the groove to suppress undesirable interference or crosstalk of the reference signals in adjacent V-grooves. In the reproduction of such reference signals, two laser beam spots are respectively irradiated on the first and second oblique surface tracks in the V-groove. Two electric signals made by detecting the light reflected from the spots are examined to determine whether they are in coincidence. When coincidence is confirmed, the signals are used as valid reference signals.

Abstract: A read/write optical disk system for performing high-density recording, reproduction and erasing of information signals by utilizing reversible structural changes between the crystalline and amorphous states of a chalcogenide glass film or the like and a recording, reproducing and erasing method therefor. In the method of this invention, during the period of recording and erasing, respectively, an exposed film area is first heated beyond its melting point to obtain a random state of its atomic arrangement and the rate of cooling from this melted state is controlled so as to obtain a recorded state or an erased state. This method is realized in the system by arranging a plurality of laser spots of different intensities and lengths in proximity to each other on the same track thereby ensuring high-quality erasing involving no danger of any incomplete erasure.

Abstract: An optical disk recording and reproducing system which uses an optical disk at least one side of which is formed with a spiral groove which has a V-shaped or inverted-trapezoid-shaped cross sectional configuration. Both the radially inward and outward sloped faces of the groove are used as recording tracks which are tracked or scanned with the spot of a light beam in the case of recording or reproduction.

Abstract: An optical reproducing device for reproducing still image signals recorded on circular tracks and moving image or audio signals recorded on spiral tracks on a disk. Concentric and spiral tracks may be intermingled on the same disk. The address signals for each concentric track or each coil of a spiral track are previously recorded. When the address signals are reproduced, they are processed so as to detect whether the readout address signals changes with time, thereby detecting whether the accessed track is concentric or spiral. An optical head drive system is controlled in a manner depending on whether the track is circular or spiral, so that an optical head can scan the desired concentric or spiral track.

Abstract: An apparatus for recording, reproducing and erasing for an optical recording disc capable of recording information data with a high density, and capable of recording new information data and simultaneously erasing the previously recorded information data.