Apparatus and method for recording optical information, apparatus and method for reproducing optical information, and apparatus and method for recording/reproducing optical information

An optical information recording method for recording information in a recording medium having an information recording layer for information to be recorded in through the use of holography, one side of the information recording layer being irradiated with light for recording or reproducing information, and a reflecting surface being provided on the other side of the information recording layer, the method comprising:

• the step of generating information light that carries information;
• the step of generating recording-specific reference light;
• and
• the recording step in which the information recording layer is irradiated with the information light and the recording-specific reference light such that the information is recorded in the information recording layer in the form of an interference pattern resulting from interference between the information light and the recording-specific reference light, wherein
• in the recording step, the information light and the recording-specific reference light are projected coaxially onto the one side of the information recording layer such that the information light and the recording-specific reference light converge to a minimum diameter at an identical position located off the reflecting surface, and the information is thereby recorded in the information recording layer in the form of an interference pattern resulting from interference between the information light yet to impinge on the reflecting surface and the recording-specific reference light reflected by the reflecting surface and an interference pattern resulting from interference between the recording-specific reference light yet to impinge on the reflecting surface and the information light reflected by the reflecting surface.

An optical information reproducing apparatus for reproducing information through the use of holography from a recording medium having an information recording layer for information to be recorded in through the use of holography, one side of the information recording layer being irradiated with light for recording or reproducing information, a reflecting surface being provided on the other side of the information recording layer, the information being recorded in the information recording layer based on information light and recording-specific reference light in the form of an interference pattern resulting from interference between the information light yet to impinge on the reflecting surface and the recording-specific reference light reflected by the reflecting surface and an interference pattern resulting from interference between the recording-specific reference light yet to impinge on the reflecting surface and the information light reflected by the reflecting surface, the information light and the recording-specific reference light being projected coaxially onto the one side of the information recording layer so as to converge to a minimum diameter at an identical position located off the reflecting surface, the apparatus comprising:

• a reproduction-specific reference light generator for generating reproduction-specific reference light;
• a reproducing optical system for irradiating the information recording layer with the reproduction-specific reference light generated by the reproduction-specific reference light generator and for collecting reproduction light generated at the information recording layer when irradiated with the reproduction-specific reference light;
• and
• a detector for detecting the reproduction light collected by the reproducing optical system, wherein
• the reproducing optical system projects the reproduction-specific reference light onto the information recording layer such that the reproduction-specific reference light converges to a minimum diameter at the same position where the information light and the recording-specific reference light converge to a minimum diameter, and performs the projection of the reproduction-specific reference light and the collection of the reproduction light on the one side of the information recording layer such that the reproduction-specific reference light and the reproduction light are arranged coaxially.

An optical information reproducing method for reproducing information through the use of holography from a recording medium having an information recording layer for information to be recorded in through the use of holography, one side of the information recording layer being irradiated with light for recording or reproducing information, a reflecting surface being provided on the other side of the information recording layer, the information being recorded in the information recording layer based on information light and recording-specific reference light in the form of an interference pattern resulting from interference between the information light yet to impinge on the reflecting surface and the recording-specific reference light reflected by the reflecting surface and an interference pattern resulting from interference between the recording-specific reference light yet to impinge on the reflecting surface and the information light reflected by the reflecting surface, the information light and the recording-specific reference light being projected coaxially onto the one side of the information recording layer so as to converge to a minimum diameter at an identical position located off the reflecting surface, the method comprising:

• the step of generating reproduction-specific reference light;
• the reproducing step in which the information recording layer is irradiated with the reproduction-specific reference light generated by the reproduction-specific reference light generator, and reproduction light generated at the information recording layer when irradiated with the reproduction-specific reference light is collected;
• and
• the step of detecting the reproduction light, wherein
• in the reproducing step, the reproduction-specific reference light is projected onto the information recording layer so as to converge to a minimum diameter at the same position where the information light and the recording-specific reference light converge to a minimum diameter, and the projection of the reproduction-specific reference light and the collection of the reproduction light are performed on the one side of the information recording layer such that the reproduction-specific reference light and the reproduction light are arranged coaxially.

An optical information recording/reproducing apparatus for recording information in a recording medium having an information recording layer for information to be recorded in through the use of holography, one side of the information recording layer being irradiated with light for recording or reproducing information, and a reflecting surface being provided on the other side of the information recording layer, and for reproducing information from the recording medium, the apparatus comprising:

• an information light generator for generating information light that carries information;
• a recording-specific reference light generator for generating recording-specific reference light;
• a reproduction-specific reference light generator for generating reproduction-specific reference light;
• a recording/reproducing optical system for, to record information, irradiating the information recording layer with the information light generated by the information light generator and the recording-specific reference light generated by the recording-specific reference light generator such that information is recorded in the information recording layer in the form of an interference pattern resulting from interference between the information light and the recording-specific reference light, and, to reproduce information, irradiating the information recording layer with the reproduction-specific reference light generated by the reproduction-specific reference light generator and collecting reproduction light generated at the information recording layer when irradiated with the reproduction-specific reference light;
• and
• a detector for detecting the reproduction light collected by the recording/reproducing optical system, wherein:
• to record information, the recording/reproducing optical system projects the information light and the recording-specific reference light coaxially onto the one side of the information recording layer such that the information light and the recording-specific reference light converge to a minimum diameter at an identical position located off the reflecting surface, and thereby records the information in the information recording layer in the form of an interference pattern resulting from interference between the information light yet to impinge on the reflecting surface and the recording-specific reference light reflected by the reflecting surface and an interference pattern resulting from interference between the recording-specific reference light yet to impinge on the reflecting surface and the information light reflected by the reflecting surface, and
• to reproduce information, the recording/reproducing optical system projects the reproduction-specific reference light onto the information recording layer such that the reproduction-specific reference light converges to a minimum diameter at the same position where the information light and the recording-specific reference light converge to a minimum diameter, and performs the projection of the reproduction-specific reference light and the collection of the reproduction light on the one side of the information recording layer such that the reproduction-specific reference light and the reproduction light are arranged coaxially.

An optical information recording/reproducing method for recording information in a recording medium having an information recording layer for information to be recorded in through the use of holography, one side of the information recording layer being irradiated with light for recording or reproducing information, and a reflecting surface being provided on the other side of the information recording layer, and for reproducing information from the recording medium, the method comprising:

• the step of generating information light that carries information;
• the step of generating recording-specific reference light;
• the recording step in which the information recording layer is irradiated with the information light and the recording-specific reference light such that the information is recorded in the information recording layer in the form of an interference pattern resulting from interference between the information light and the recording-specific reference light;
• the step of generating reproduction-specific reference light;
• the reproducing step in which the information recording layer is irradiated with the reproduction-specific reference light, and reproduction light generated at the information recording layer when irradiated with the reproduction-specific reference light is collected;
• and
• the step of detecting the reproduction light, wherein:
• in the recording step, the information light and the recording-specific reference light are projected coaxially onto the one side of the information recording layer such that the information light and the recording-specific reference light converge to a minimum diameter at an identical position located off the reflecting surface, and the information is thereby recorded in the information recording layer in the form of an interference pattern resulting from interference between the information light yet to impinge on the reflecting surface and the recording-specific reference light reflected by the reflecting surface and an interference pattern resulting from interference between the recording-specific reference light yet to impinge on the reflecting surface and the information light reflected by the reflecting surface;
• and
• in the reproducing step, the reproduction-specific reference light is projected onto the information recording layer so as to converge to a minimum diameter at the same position where the information light and the recording-specific reference light converge to the minimum diameter, and the projection of the reproduction-specific reference light and the collection of the reproduction light are performed on the one side of the information recording layer such that the reproduction-specific reference light and the reproduction light are arranged coaxially.