Apparatus and method for recording and reproducing information to and from an optical storage medium

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

• a step of generating information light that carries information;
• a step of generating recording-specific reference light;
• and
• a 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 they converge on the reflecting surface, and
• in the recording step, each of the information light and the recording-specific reference light is made to have directions of polarization that are different between respective half areas of a cross section of a beam thereof such that the direction of polarization of the information light yet to impinge on the reflecting surface coincides with that of the recording-specific reference light reflected by the reflecting surface, and the direction of polarization of the recording-specific reference light yet to impinge on the reflecting surface coincides with that of the information light reflected by the reflecting surface.

An optical information reproducing apparatus for reproducing information through the use of holography from an optical information recording medium having an information recording layer in which information is recorded through the use of holography and one side which is irradiated with light for recording or reproducing information, and a reflecting surface disposed 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 that are projected coaxiaUy onto the one side of the information recording layer such that they converge on the reflecting surface, 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 apparatus comprising:

• reproduction-specific reference light generation means 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 generation means and for collecting reproduction light generated at the information recording layer when irradiated with the reproduction-specific reference light;
• and
• detection means 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 to allow it to converge on the reflecting surface, such that the irradiation with the reproduction-specific reference light and the collection of the reproduction light are performed on the one side, and that the reproduction-specific reference light and the reproduction light are arranged coaxially, and
• the reproducing optical system has optical rotation means for optically rotating light passing therethrough in directions different between respective half areas of a cross section of a beam of the light, and optically rotates, with the optical rotation means, the reproduction-specific reference light having a predetermined first direction of polarization to convert the same into reproduction-specific reference light having directions of polarization different between the respective areas to irradiate the information recording layer therewith, and optically rotates, with the optical rotation means, the reproduction light and return light resulting from the reproduction-specific reference light reflected by the reflecting surface to convert them into reproduction light having the first direction of polarization over an entire cross section of a beam thereof and return light having a second direction of polarization different from the first direction of polarization over an entire cross section of a beam thereof.

An optical information reproducing method for reproducing information through the use of holography from an optical information recording medium having an information recording layer in which information is recorded through the use of holography and one side of which is irradiated with light for recording or reproducing information, and a reflecting surface disposed 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 that are projected coaxially onto the one side of the information recording layer such that they converge on the reflecting surface, 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 method comprising;

• a step of generating reproduction-specific reference light;
• a reproducing step in which the information recording layer is irradiated with the reproduction-specific reference light generated by the reproduction-specific reference light generation means, and reproduction light generated at the information recording layer when irradiated with the reproduction-specific reference light is collected;
• and
• a 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 on the reflecting surface such that the irradiation with the reproduction-specific reference light and the collection of the reproduction light are performed on the one side, and that the reproduction-specific reference light and the reproduction light are arranged coaxially, and
• in the reproducing step, the reproduction-specific reference light having a predetermined first direction of polarization is optically rotated in directions different between respective half areas of a cross section of a beam thereof, and thereby converted into reproduction-specific reference light having directions of polarization different between the respective areas to irradiate the information recording layer therewith, and the reproduction light and return light resulting from the reproduction-specific reference light reflected by the reflecting surface are each optically rotated in directions different between the respective areas and thereby converted into reproduction light having the first direction of polarization over an entire cross section of a beam thereof and return light having a second direction of polarization different from the first direction of polarization over an entire cross section of a beam thereof.

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

• information light generation means for generating information light that carries information;
• recording-specific reference light generation means for generating recording-specific reference light;
• reproduction-specific reference light generation means 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 generation means and the recording-specific reference light generated by the recording-specific reference light generation means 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 generation means and collecting reproduction light generated at the information recording layer when irradiated with the reproduction-specific reference light;
• and
• detection means for detecting the reproduction light collected by the recording/reproducing optical system, wherein
• the recording/reproducing optical system has optical rotation means for optically rotating light passing therethrough in directions different between respective half areas of a cross section of a beam of the light,
• 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 they converge on the reflecting surface,
• to record information, the recording/reproducing optical system optically rotates, with the optical rotation means, each of the recording-specific reference light having a predetermined first direction of polarization and the information light having a second direction of polarization different from the first direction of polarization to cause each of the information light and the recording-specific reference light to have directions of polarization different between the respective areas, such that the direction of polarization of the information light yet to impinge on the reflecting surface coincides with that of the recording-specific reference light reflected byte reflecting surface, and the direction of polarization of the recording-specific reference light yet to impinge on the reflecting surface coincides with that of the information light reflected by the reflecting surface,
• to reproduce information, the recording/reproducing optical system projects the reproduction-specific reference light onto the information recording layer to allow it to converge on the reflecting surface, such that the irradiation with the reproduction-specific reference light and the collection of the reproduction light are performed on the one side, and that the reproduction-specific reference light and the reproduction light are arranged coaxially, and
• to reproduce information, the recording/reproducing optical system optically rotates, wit the optical rotation means, the reproduction-specific reference light having the first direction of polarization to convert the same into reproduction-specific reference light having directions of polarization different between the respective areas to irradiate the information recording layer therewith, and optically rotates, with the optical rotation means, the reproduction light and return light resulting from the reproduction-specific reference light reflected by the reflecting surface to convert them into reproduction light having the first direction of polarization over an entire cross section of a beam thereof and return light having a second direction of polarization different from the first direction of polarization over an entire cross section of a beam thereof.

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

• a step of generating information light that carries information;
• a step of generating recording-specific reference light;
• a 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;
• a step of generating reproduction-specific reference light;
• a 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
• a 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 they converge on the reflecting surface,
• in the recording step, each of the recording-specific reference light having a predetermined first direction of polarization and the information light having a second direction of polarization different from the first direction of polarization is optically rotated in directions different between respective half areas of a cross section of a beam thereof to cause each of the information light and the recording-specific reference light to have directions of polarization different between the respective areas, such that the direction of polarization of the information light yet to impinge on the reflecting surface coincides with that of the recording-specific reference light reflected by the reflecting surface, and the direction of polarization of the recording-specific reference light yet to impinge on the reflecting surface coincides with that of the information light reflected by the reflecting surface,
• in the reproducing step, the reproduction-specific reference light is projected onto the information recording layer so as to converge on the reflecting surface, such that the irradiation with the reproduction-specific reference light and the collection of the reproduction light are performed on the one side, and that the reproduction-specific reference light and the reproduction light are arranged coaxially, and
• in the reproducing step, the reproduction-specific reference light having a predetermined first direction of polarization is optically rotated in directions different between respective half areas of a cross section of a beam thereof, and thereby converted into reproduction-specific reference light having directions of polarization different between the respective areas to irradiate the information recording layer therewith, and the reproduction light and return light resulting from the reproduction-specific reference light reflected by the reflecting surface are each optically rotated in directions different between the respective areas and thereby converted into reproduction light having the first direction of polarization over an entire cross section of a beam thereof and return light having a second direction of polarization different from the first direction of polarization over an entire cross section of a beam thereof.