The invention discloses a holographic multiplex recording method, which combines technical advantages of angle multiplexing and shift multiplexing, and improves capacity and stability of a system. A medium contracts and expands due to environmental temperature fluctuations, which causes broken Bragg condition. However, the angle multiplexing has the advantages that the broken Bragg condition caused by contraction and expansion of the medium can be corrected by controlling an incident angle of a reference beam and an emitting wavelength of a laser, and the problem of a weak reproduction signal caused by the environmental temperature fluctuations is solved. On the other hand, the advantages of shift multiplex recording are that cross-write noise is not accumulated and that a multiplexing number can be improved by using a cross-shift multiplex method.

According to the present invention, a large-capacity recording device with high stability is realized by combining the two technologies.

The invention discloses a holographic multiplex recording method, which combines technical advantages of angle multiplexing and shift multiplexing, and improves capacity and stability of a system. A medium contracts and expands due to environmental temperature fluctuations, which causes broken Bragg condition. However, the angle multiplexing has the advantages that the broken Bragg condition caused by contraction and expansion of the medium can be corrected by controlling an incident angle of a reference beam and an emitting wavelength of a laser, and the problem of a weak reproduction signal caused by the environmental temperature fluctuations is solved. On the other hand, the advantages of shift multiplex recording are that cross-write noise is not accumulated and that a multiplexing number can be improved by using a cross-shift multiplex method.

According to the present invention, a large-capacity recording device with high stability is realized by combining the two technologies.

A recording layer for an optical data recording medium is described. Recording is performed by irradiating the recording layer with a laser beam. The recording layer contains a W oxide, an Fe oxide, and at least one of a Ta oxide and a Nb oxide. The recording layer contains 10-60 atomic % of Fe and a total of 3-50 atomic % of Ta and Nb relative to the total metal atoms therein.

A recording layer for an optical data recording medium is described. Recording is performed by irradiating the recording layer with a laser beam. The recording layer contains a W oxide, an Fe oxide, and at least one of a Ta oxide and a Nb oxide. The recording layer contains 10-60 atomic % of Fe and a total of 3-50 atomic % of Ta and Nb relative to the total metal atoms therein.

Systems and methods for long-term non-volatile non-rotating optical storage of digital information rely on storage elements that include optical storage media, an access subsystem configured to access bits of information from one of the storage elements, and a support structure configured to support multiple storage elements. A laser used to retrieve and/or record bits of digital information may be moved along two orthogonal dimensions while the storage element is non-rotating.

Systems and methods for long-term non-volatile non-rotating optical storage of digital information rely on storage elements that include optical storage media, an access subsystem configured to access bits of information from one of the storage elements, and a support structure configured to support multiple storage elements. A laser used to retrieve and/or record bits of digital information may be moved along two orthogonal dimensions while the storage element is non-rotating.

An optical disc device includes: an optical pickup including a first laser light source that emits laser light, an objective lens that focuses the laser light emitted from the first laser light source onto an optical disc, and a light receiving element that receives reflected light from the optical disc, and performs photoelectric conversion on the reflected light received to output a received-light signal; an FS signal generator that generates an FS signal indicating the light amount of the reflected light from the optical disc, based on the received-light signal from the light receiving element; and a dirt determiner that determines that dirt is present in the optical pickup, when the peak level of the FS signal is less than a dirt determination threshold, and controls the light receiving element to increase the peak level of the received-light signal from the light receiving element.

An optical disc device includes: an optical pickup including a first laser light source that emits laser light, an objective lens that focuses the laser light emitted from the first laser light source onto an optical disc, and a light receiving element that receives reflected light from the optical disc, and performs photoelectric conversion on the reflected light received to output a received-light signal; an FS signal generator that generates an FS signal indicating the light amount of the reflected light from the optical disc, based on the received-light signal from the light receiving element; and a dirt determiner that determines that dirt is present in the optical pickup, when the peak level of the FS signal is less than a dirt determination threshold, and controls the light receiving element to increase the peak level of the received-light signal from the light receiving element.

In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.

In a multilayer optical disc having information layers conforming to a plurality of different optical disc standards, because the type of each information layer is not recorded in the other information layers, in read and write operations by a compatible optical disc device conforming to a plurality of optical disc standards, every time the information layer being accessed changes, it has been necessary to read the type of the information layer and select a method of generating a tracking error signal adapted to the type of information layer, so access has taken time. In order to solve the above problem, in the optical multilayer disc according to the present invention, having information layers conforming to a plurality of different optical disc standards, in an area in one of the information layers, information about the other information layers is recorded. The time required to access the other information layers can be reduced by using this information to select a tracking error signal generating method.