摘要:
An optical disk including a transparent plastic substrate, a recording film formed on an one side surface of said substrate, a first protective film covering said recording film, and a moisture-impermeable film formed on the other side surface of said substrate via or not via an intermediate film.
摘要:
A reproducing optical device for a magneto-optical recording medium related to the present invention having light sources that emit linearly polarized lights towards a magneto-optical recording medium, polarization directions of the linearly polarized lights being mutually orthogonal. A quarter wavelength plate disposed between the recording medium and the light sources converts each of the linearly polarized lights into right and left circularly polarized lights respectively. Corresponding to recorded information, the recording medium has magnetized sections that are magnetized in a perpendicularly upward and downward direction with respect to a medium surface. Moreover, the recording medium displays the property of circular dichroism. When the right circularly polarized light and the left circularly polarized light are reflected off the recording medium, a first and a second photodetector generate a first and a second reproduced signal respectively, based on variation in reflected light intensity of each of the circularly polarized lights. This variation corresponds to the upward and the downward magnetization directions of the magnetized sections and is due to the circular dichroism effect. There is a phase difference of half a cycle between the first and the second reproduced signal and the signals vary inversely with respect to each other. Consequently, disk noise is cancelled by differentially amplifying the first and the second reproduced signal, and an SN ratio of a reproduced signal thereby can be improved.
摘要:
A transparent substrate of an optical memory is produced by injection molding using a stamper. Grooves and lands are alternately arranged on the optical memory, for tracking of light converged on the optical memory. The groove width is set in the range of 0.3 .mu.m to 0.4 .mu.m and the groove depth is set in the rage of 80 nm to 100 nm. A decrease in the width of a land at each edge is restrained to 0.2 .mu.m in maximum. With such dimensions, even when the track pitch is set to about 1.4 .mu.m, it is possible to obtain a track crossing signal with intensity sufficient for performing an access operation to a target track. Moreover, since the dimensions bring about an improved reflectance at a land, the optical memory achieves an improved C/N and recording density.
摘要:
A magneto optical disk comprising: a circular substrate; a recording layer, formed on the substrate, for magneto-optical recording of information; a readout layer, formed between the substrate and the recording layer, for the reproduction of information recorded on the recording layer, wherein the readout layer has a Curie temperature which is higher than the Curie temperature of the recording layer, and exhibits in-plane magnetization at room temperature and a change from in-plane magnetization to perpendicular magnetization when its temperature rises over a certain temperature as a result of the application of a light beam, and wherein the magnetic compensation temperature is set such that it increases from the peripheral edge of the magneto-optical disk toward the center thereof. When the magneto-optical disk is used with a magneto-optical recording and reproducing device using a CAV system, it achieves high-density recording and the reproduction of signals with reduced noise, without causing the light beam control system to be complicated.
摘要:
An optical disc having a recording film formed on one surface of a plastics substrate transparent to light, a first protection film formed on the recording film, a moisture proof film formed on the other surface of the substrate, and a second protection film formed on the moisture proof film.
摘要:
A magneto-optical recording medium includes a readout layer having in-plane magnetization at room temperature and in which a transition occurs from in-plane magnetization to a perpendicular magnetization when temperature rises, and a recording layer for storing information thereon magneto-optically. In the readout layer made of GdFeCo by adding Nd thereto, an amount of Nd to be added changes in a direction perpendicular to its film surface, and an amount of Nd is larger on a light incidence side than on the other side. As a result, even when a laser with a short wavelength is used, high density recording can be achieved as undesirable recording and reproducing operations due to a change in a magnetic interaction is prevented and also deterioration in quality of a reproducing signal is prevented.
摘要:
A magneto-optical recording medium includes a readout layer has in-plane magnetization at room temperature and in which a transition occurs from in-plane magnetization to perpendicular magnetization when temperature thereof is raised, and a recording layer for recording thereon information. The composition of the readout layer varies in a direction perpendicular to the surface thereof, and in the readout layer, the Co density on the light incident side is higher than the Co density on the interface between the readout layer and the recording layer. Therefore, the Curie temperature on the reproducing light incident side of the readout layer is high and the the polar Kerr rotation angle in reproducing increases, thereby achieving improvements in a reproducing signal quality. On the other hand, since the Curie temperature on the interface is low, the shift of the threshold temperature at which a transition occurs from in-plane to perpendicular by the magnetic interaction between the layers can be suppressed, thereby achieving a high quality reproducing signal without changing the laser power required for reproduction very much.
摘要:
A transparent substrate of an optical memory is produced by injection molding using a stamper. Grooves and lands are alternately arranged on the optical memory, for tracking of light converged on the optical memory. The groove width is set in the range of 0.3 .mu.m to 0.4 .mu.m and the groove depth is set in the rage of 80 nm to 100 nm. A decrease in the width of a land at each edge is restrained to 0.2 .mu.m in maximum. With such dimensions, even when the track pitch is set to about 1.4 .mu.m, it is possible to obtain a track crossing signal with intensity sufficient for performing an access operation to a target track. Moreover, since the dimensions bring about an improved reflectance at a land, the optical memory achieves an improved C/N and recording density.
摘要:
A magnetic recording medium having a recording layer made up of a ferrimagnetic material whose compensation temperature is included within room temperatures and an information recording-reproduction method using the magnetic recording medium. During recording, while a light beam is projected on the recording layer so as to raise the temperature of a recording portion, information is recorded by applying a signal magnetic field from a magnetic head. During reproduction, while a light beam is projected on a reproducing portion of the recording layer so as to raise the temperature thereof, information is reproduced by detecting leakage flux from the reproducing portion by the magnetic head. Thus, during reproduction, no magnetic flux is generated from other portions of the recording layer not irradiated by the light beam. With the arrangement, crosstalk due to leakage flux from adjoining tracks not irradiated by the optical beam can be eliminated. Therefore, track pitches can be made narrower so as to increase recording density of the magnetic recording medium. Further, since crosstalk from adjoining tracks is eliminated, a high S/N can be achieved.
摘要:
A magneto-optical memory device is provided with a base whereon a first magnetic film which exhibits in-plane magnetization at room temperature and exhibits perpendicular magnetization at above room temperature, a second magnetic film having its Curie temperature above room temperature; and a third magnetic film having its Curie temperature set above the Curie temperature of the second magnetic film, which exhibits perpendicular magnetization in a temperature range between room temperature and Curie temperature are laminated in this order. When recording, the temperature of the third magnetic film is raised to the vicinity of its Curie temperature, and information is recorded thereon by an external magnetic field. As the magnetization of the second magnetic film having a temperature rise above its Curie temperature disappears, an exchange coupling force is not exerted between the first magnetic film and the third magnetic film. In the above arrangement, since the effect from the magnetization of the first magnetic film can be avoided, information can be recorded on the third magnetic film by a small external magnetic field, thereby permitting a reduction in electric power consumption and in the size of the apparatus.