Abstract: A phase error detection apparatus and method is disclosed whereby a data signal is played back at a high S/N ratio from a magneto-optical disk making use of a ghost signal by magnetic domain wall displacement detection while the playback laser poser is kept at an optimum level. First, the laser power is controlled so that the time delay of a ghost signal from a data signal may be equal to a fixed multiple of a data detection clock. Thereupon, a laser power control section searches for a point at which the amount of jitters generated is small based on a RF signal. Then, the playback laser power is adjusted so that the time delay amount of the ghost signal from the data signal may be the fixed multiple n=5 of the clock nearest to the phase delay amount set in advance of a ghost which appears in the isothermal region with a laser power with which an optimum signal characteristic is obtained.

Abstract: The present invention provides an optical recording medium including a recording layer and a light-transmitting layer successively formed on one side of a substrate, so that a light is applied from the side of this light-transmitting layer for performing an information recording and/or reproduction. On the opposite side of the substrate not having the light-transmitting layer, a water-proof film consisting of at least one layer is formed. This suppresses the skew, enabling to improve the information recording and/or reproduction characteristics for a higher recording density. Furthermore, if the light-transmitting layer has a thickness t=3 to 177 micrometers in an information signal section of the recording medium, and a thickness fluctuation &Dgr;t ≦±5.26 (&lgr;/NA4) micrometers (wherein NA is a numerical aperture and &lgr; is a wavelength of the recording/reproduction optical system), it is possible to realize a high NA and a high capacity.

Abstract: An optical disc and its manufacturing method in which humps may be prohibited from being formed on an outer rim area of the disc to assure optimum surface properties of a light transmitting layer of the disc to contribute to further increase in recording capacity. On a substrate 2 of an optical disc 1 are sequentially formed a recording portion 6 and a light transmitting layer 5. The light falls on the light transmitting layer 5 to record and/or reproduce information signals for a signal recording area 6a of the substrate 2. The radial distance D from the outermost rim of the substrate 2 to the signal recording area 6a is selected to be larger than the radial width L of a hump 5a formed on the outer rim of the light transmitting layer 5. The hump 5a has a height h from the surface of the light transmitting layer 5 not larger than 70 &mgr;m.

Abstract: An optical disc and its manufacturing method in which humps may be prohibited from being formed on an outer rim area of the disc to assure optimum surface properties of a light transmitting layer of the disc to contribute to further increase in recording capacity. On a substrate 2 of an optical disc 1 are sequentially formed a recording portion 6 and a light transmitting layer 5. The light falls on the light transmitting layer 5 to record and/or reproduce information signals for a signal recording area 6a of the substrate 2. The radial distance D from the outermost rim of the substrate 2 to the signal recording area 6a is selected to be larger than the radial width L of a hump 5a formed on the outer rim of the light transmitting layer 5. The hump 5a has a height h from the surface of the light transmitting layer 5 not larger than 70 &mgr;m.

Abstract: An optical recording medium incorporating a supporting body; a recording portion which is formed on either main surface of the supporting body and on which a signal is recorded; and a light permeable layer formed on the recording portion, wherein light is applied from a position adjacent to the light permeable layer to record/reproduce a signal, and carboxylic acid amine salt expressed by general formula (1) and/or general formula (2) is held on the surface which is irradiated with light where n is an integer from 1 to 3, each of R1 and R2 is hydrogen or a hydrocarbon group, R3 is a hydrocarbon group and Rf is a perfluoroalkyl group having three or more carbon atoms, where at least either of R1 and R2 is perfluoroalkyl group having three or more carbon atoms, at least any one of R1, R2, R3, R4 and R5 is hydrocarbon group having 12 or more carbon atoms and the rest of them are hydrogen or hydrocarbon group.

Abstract: According to the present invention, when a land-groove recording method is adopted, thermal crosstalk between a land and an adjoining groove is suppressed effectively. Inhomogeneity of a recording layer between the land and groove is suppressed effectively. A substrate for optical recording media comprises groove-like concave parts (2) and convex parts each created between adjoining concave parts. A border sidewall (4) between a concave part and an adjoining convex part (2) has a plurality of sidewall planes, that is, at least a first sidewall plane (41) that leads to the bed of the concave part and a second sidewall plane (42) that leads to the apical plane of the convex part. The first sidewall plane meets the bed of the concave part at an angle ranging from 120° to less than 180°. The second sidewall plane meets the bed of the concave part at an angle ranging from 90° to 110°.

Abstract: A novel multi-layer optical disc according to the present invention can treat a large volume of information without deterioration in level of reproduction signals from the respective information storage layers thereof. The multi-layer optical disc comprises a substrate having a light-transmission property, a read-only-memory type information storage portion formed on the substrate, a semi-transmission layer disposed on the read-only-memory type information storage portion, a spacer layer disposed on the semi-transmission layer and having a light-transmission property, and a rewritable information storage layer disposed on said spacer layer.

Abstract: In a magneto-optical recording/reproducing apparatus in which a signal is recorded by the magnetic field modulation system and which has a device for applying an external magnetic field at the time of reproduction, the apparatus has an external magnetic field generating electromagnet commonly used for recording and reproducing, the inductance of a coil in the electromagnet at the time of reproduction is larger than the inductance of the coil at the time of recording.