Abstract: A tracking servo method of an optical video disc player and its special device which accomplish angle adjustment in a simple, time-saving and effort-saving manner and improve the tracking servo capability of the optical video disc player. In the tracking servo method of an optical video disc player, a laser beam is split into a main beam and two sub beams, and tracking error signal generated from the two sub beams are subtracted from tracking error signal generated by the main beam; light spot of the main beam is circular in shape, and light spots of the two sub beams are elliptical in shape. The special device has an effective grating region (1). The effective grating region (1) has a middle zone (2) and two side zones (3, 4); the middle zone (2) has two side edges which are parallel and equal in length, and the two side edges has a distance therebetween which is 10-90% of diameter of the effective grating region (1), and the middle zone (2) and the two side zones (3, 4) have different grating pitches.

Abstract: A hologram disc reading and writing apparatus including a signal light source module, a beam splitter, a reference/reading light source, a reflector, and an optical reading head and a hologram disc reading apparatus are provided. A signal light beam emitted from the signal light source module is transmitted to a data region of a hologram disc through the beam splitter. The reference/reading light source, the signal light source module, and the optical reading head are disposed at the same side of the hologram disc. The reflector is disposed at the other side. A spherical wave light beam emitted from the reference/reading light source is transmitted through the data region and reflected by the reflector to form a phase conjugate light beam transmitted to and through the data region. The phase conjugate light beam is transformed to a data light beam transmitted to the optical reading head through the beam splitter.

Abstract: To provide a recording method of a multilayered optical disk having three or more recording layers, for performing recording while securing sufficient test areas without reducing user data areas, and while suitably controlling the power of laser beam irradiated onto each of the layers. The method uses an optical disk which has at least a first recording layer and a second recording layer located on the side nearer to the light incident surface than the first recording layer, and which respectively has a first test area configured by a plurality of segments in the first recording layer and a second test area configured by a plurality of segments in the second recording layer.

Abstract: According to one embodiment, a write-once type information storage medium comprises an organic dye based recording material having sensitivity at a wavelength of 405 nm and at a recording wavelength in the range of 600 nm to 700 nm, wherein, when absorbance of a maximum absorption wavelength in the vicinity of 405 nm is defined as 1, the absorbance is 5% or more at any wavelength in the range of 600 nm to 700 nm.

Abstract: An information recording medium, comprising N number (N is an integer fulfilling N?3) of information layers on which information is recordable, and allowing information to be recorded on each of the information layers and allowing information recorded on each of the information layers to be reproduced by being irradiated with laser light. The N number of information layers include an N'th information layer, an (N?1)th information layer, an (N?2)th information layer, . . . a second information layer and a first information layer sequentially located from a laser light incidence side. A reflectance of the N'th information layer is RN, and a reflectance of an M'th information layer (M refers to every integer fulfilling N>M?1) is RM.

Abstract: There are provided an optical data storage medium and methods of optical data storage using the same. The optical data storage medium comprises a non-linear sensitizer capable of absorbing actinic radiation to cause upper triplet energy transfer to a reactant that undergoes a photochemical change upon triplet excitation.

Abstract: According to one embodiment, a write-once type information storage medium comprises an organic dye based recording material having sensitivity at a wavelength of 405 nm and at a recording wavelength in the range of 600 nm to 700 nm, wherein, when absorbance of a maximum absorption wavelength in the vicinity of 405 nm is defined as 1, the absorbance is 5% or more at any wavelength in the range of 600 nm to 700 nm.

Abstract: Provided is an optical disk drive including: an actuator for driving an objective lens for applying a beam from a laser to an optical disk to cause a focal point of the beam to move in a focus direction; and a servo controller for receiving an input of a focus error signal and driving the actuator to control a focusing position of the beam, which includes: a compensation unit for generating a drive signal for the actuator based on the focus error signal; a noise detection unit for detecting a noise component by changing a limiter characteristic according to a frequency of the drive signal; and a correction unit for correcting the drive signal by subtracting the noise component from the drive signal. Accordingly, an influence of a tracking error signal leaking into the focus error signal in a focus servo system can be reliably suppressed.

Abstract: A holographic data storage system that includes a write head that includes a pixellated spatial light modulator and a separate or integral phase mask that varies the phase depending on the location in the phase mask that light passes through. The phase variation can be changed over time in a random, pseudo-random, or predetermined fashion. The spatial light modulator and phase mask can be implemented in a liquid crystal SLM (nematic, ferroeleletric, or other), in a DMD SLM, in a magneto-optical SLM, or in any other suitable manner.

Abstract: A disc device capable of achieving a slimming down of a tilt adjusting portion is provided. A tilt adjusting member 404 of a tilt adjusting portion 400 moves an optical pickup driving portion 307 along a guide face 401a to adjust a light beam 303b emitted from an optical pickup 303 such that an optical axis 303c is set perpendicularly to a disc 200. Since the tilt adjusting member 404 is moved in a direction oblique to the guide face 401a and a direction perpendicular to the optical pickup driving portion 307, an amount of movement of the tilt adjusting member 404 can be reduced smaller than a necessary amount of tilt adjustment of the optical pickup driving portion 307 and also a slimming down of the tilt adjusting portion 400 can be achieved.

Abstract: An initialization apparatus that has a simplified configuration and that forms an initial hologram in an information recording medium is provided. An initialization apparatus (10) rotates an optical disk (100) and emits blue light beams (Lb1) and (Lb2) to either side of the optical disk (100) while causing a red light beam (Lr1) to follow a track formed in a reference layer (102). Thus, the initialization apparatus (10) can perform an initialization process in which a linear initial hologram IH is formed in a recording layer (101) in a spiral pattern that corresponds to the track formed in a reference layer (102). Accordingly, the initialization apparatus (10) can form a planar initial hologram layer (YH) with significantly reduced optical energy or thermal energy emitted to the optical disk (100) at one time.

Abstract: An optical disc device including: a light source; an object lens to focus light emitted from the light source on an information recording surface of an optical disc; a movable lens that is arranged on an optical path between the light source and the objective lens and arranged such that position thereof is adjustable along a direction of a light axis; a lens moving portion to move the movable lens along the direction of the light axis; a tracking servo system which makes a beam spot that is formed of the light from the light source through focusing by the objective lens keep on track of the optical disc; and a control part which controls gain of a servo loop of the tracking servo system is made temporarily larger when the movable lens is moved by the lens moving portion in comparison with a case where moving of the movable lens by the lens moving portion is not performed.

Abstract: A method is disclosed to store information in a holographic data storage medium. The method provides a hologram comprising an alignment pattern, and disposes that hologram into a holographic data storage medium during manufacture.

Abstract: By referring to a table of reproducing conditions and medium specific parameters, stored in an optical disc or optical disc apparatus and/or generated by the optical disc apparatus, the medium specific parameters to be used for performing reproducing power adjustment are changed in accordance with the reproducing condition to execute reproducing power adjustment.

Abstract: According to one embodiment, a write-once type information storage medium comprises an organic dye based recording material having sensitivity at a wavelength of 405 nm and at a recording wavelength in the range of 600 nm to 700 nm, wherein, when absorbance of a maximum absorption wavelength in the vicinity of 405 nm is defined as 1, the absorbance is 5% or more at any wavelength in the range of 600 nm to 700 nm.

Abstract: A signal current wiring line is configured to carry a signal current from a first circuit block to a second circuit block. A return current wiring line is configured to carry a return current from the second circuit block to the first circuit block. The signal current wiring line and the return current wiring line are stacked with an offset in the width direction so as to form a region between the surface of the casing on the second wiring line side and the signal current wiring line where the signal current wiring line faces the surface of the casing on the second wiring line side without the return current wiring line intervening between them.

Abstract: A microprocessor performs preliminary tracking servo control of an objecting lens by moving the objective lens in a radial direction of an optical disc so as to allow a laser beam reflected by the optical disc to be equally divided and received by first and second light receiving sections PD1, PD2 of the photodiode PD before the microprocessor starts tracking servo control of the objective lens. This makes it possible to perform preliminary tracking servo control of the objective lens before tracking pull-in, and thereby to obtain an appropriate tracking error signal for performing stable tracking pull-in, even when an optical disc with an offset center of gravity is mounted on an optical disc apparatus.

Abstract: A near field optical disc and a near field optical disc reading apparatus are provided. The near field optical disc has at least one light source and a near field optical pick-up head, and the near field optical disc includes a light guiding substance, a first reflection layer and a second reflection layer. The light guiding substance has a first surface, a second surface opposite thereto and at least one light entrance window. Light emitted from the light source enters the light guiding substance through the light entrance window. The second reflection layer is disposed on the second surface. The first reflection layer is disposed on the first surface and has a plurality of light pervious holes. A part of the light is transmitted through the light pervious holes and picked up by the near field optical pick-up head.

Abstract: An objective lens driving device includes a lens holder (3) holding an objective lens (1, 2), a stationary part (5) that supports the lens holder (3) via wires (7a, 7b), an electromagnetic coil (11a-11d, 12a-12d) provided on the lens holder, and a magnet (4a, 4b) provided on the stationary part and magnetized in a multipolar manner so that different magnetic pole surfaces are arranged on a surface of the magnet facing the electromagnetic coil. The lens holder has a convex portion (16a-16d, 17a-17d) on a surface thereof facing the magnet. The convex portion has at least one groove (601-604, 701-704) portion extending parallel to a direction of magnetic flux lines of the magnet facing the convex portion, and at least a surface of the convex portion is formed of material having magnetic property.

Abstract: An apparatus and method for measuring the quality of a signal on an optical disc based on level information of a viterbi decoder are provided. The signal quality measuring apparatus includes: a binary unit that generates binary signals from input RF signals; a channel identifier that receives the input RF signals and the binary signals output from the binary unit and outputs reference level values corresponding to the binary signals; and an information calculator that receives the reference level values and detects a signal quality value.

Abstract: A recording apparatus for an optical disk drive is provided. The recording apparatus includes a driver, a servo signal generator, a filter, and a counter. The driver controls a recording speed of the optical disk drive. The servo signal generator generates at least a servo signal. The filter with a specific bandwidth filters the servo signal to generate a filtered servo signal. The counter generate a count value according to the filtered servo signal and instructs the driver to decrease the recording speed of the optical disk drive when the count value exceeds a trigger value, so as to record with the decreased recording speed.

Abstract: Even when recording data which is continuously inputted at a high speed, it is possible to correct a recording error and reproduce preferable AV data without a noise upon reproduction. A recording error detection circuit (14) detects an error generation upon recording according to the fluctuation of amplitude of a tracking error signal or a focus error signal. A recording signal processing circuit (6) again records (performs skip recording) the same data in a region subsequently adjacent to a region where a recording error has occurred. When performing the skip recording, address information contained in the recording data is rewritten into address information on a new recording region. Moreover, an identifier (skip mark) indicating that a recording error has occurred is added to the pattern of the link region of the recording data.

Abstract: Disclosed is a reflecting wavelength plate that deflects and reflects a light path and adds a phase difference with respect to plural incident light having different wavelengths. The reflecting wavelength plate includes a substrate; a reflecting film laminated on the substrate; and a sub-wavelength concavo-convex structure that is laminated on the reflecting film and has a pitch less than or equal to the shortest wavelength of the plural incident light. The filling factor and the groove depth of the sub-wavelength concavo-convex structure are determined so as to add the phase difference obtained by (k?)/8, where k is an integer, to the plural incident light having the different wavelengths.

Abstract: An optical apparatus according to the present invention comprises an optical base having a bonding surface, and an optical component fixedly bonded to the bonding surface with an adhesive. The optical base has an open hole formed in the bonding surface. The open hole is filled with the adhesive. The optical component contacts the open hole so that a part of the open hole is left unclosed.

Abstract: An optical pickup includes: first and second objective lenses focusing light beams of different wavelengths on first and second optical discs having different thickness protection layers; a coma aberration generating unit generating coma aberration in the light beams; a collimating lens between a light source and the first objective lens; and a collimating lens driving unit. The protection layer thickness of the plastic first optical disc is smaller than that of the second optical disc. The first objective lens satisfies a lens tilt coma aberration sensitivity of 0 to 0.3[?rms/°]. An optical axis of the light beam approximately coincides with an optical axis of the first objective lens. The optical pickup is inclined to the optical disc so that initial coma aberration with respect to the first optical disc is optimally corrected. The coma aberration generating unit is used for obtaining optimal reproducing environment when reproducing the second optical disc.

Abstract: Providing a soliton mode-locked solid-state laser that includes a resonator, a first end of which is formed of a semiconductor saturable absorption mirror, a solid-state laser medium, a negative group velocity dispersion compensator for compensating for group velocity dispersion within the resonator, and an excitation optical system that outputs excitation light for exciting the solid-state laser medium, and oscillates soliton pulse laser light with a repetition frequency of not less than 1 GHz, an intensity modulator that includes a waveguide electrooptic modulator for modulating intensity of the soliton pulse laser light and a driver for applying a voltage to the waveguide electrooptic modulator according to desired information, and a nonlinear optical element for converting the intensity-modulated soliton pulse laser light to a second harmonic wave.

Abstract: A holographic recording medium in which information can be reproduced by phase conjugate beam without requiring a mirror for obtaining the phase conjugate beam and its driving part and recording density is not reduced. The recording medium includes a recording layer in which an interference pattern is recorded and a light absorption/transmission layer which can be reversibly changed to be in a first state where signal beam and reference beam passed through the recording layer are absorbed at the time of recording of information and a second state where the reference beam is transmitted at the time of reproduction of information, and the reference beam transmitted through the light absorption/transmission layer is reflected by a reflection layer to produce the phase conjugate beam.

Abstract: An object of this invention is to improve stability of tracking control and improve recording and reproduction performance. The tracking control device comprises a main push-pull signal generation section, which generates a main push-pull signal based on a signal obtained by photoelectric conversion of return light of the main beam; a microcomputer, which detects an other-layer stray light signal component included in a signal obtained by photoelectric conversion of return light of the sub-beam; a signal correction section, which corrects the signal obtained by photoelectric conversion of the return light of the sub-beam, based on the other-layer stray light signal component; and a sub-push-pull signal generation section, which generates a sub-push-pull signal based on the corrected signal obtained by photoelectric conversion of the return light of the sub-beam.

Abstract: An optical pick-up actuator (1) has a lens holder (2). The lens holder has tracking (5r) and focusing (5f) coils which substantially extend in two parallel planes at a side of the lens holder (2). A magnet system (7) is arranged separately from the lens holder and extends beyond said planes, said magnet system cooperating with the tracking and focusing coils, the coil systems being arranged for effecting tilt through cooperation with the magnet system. Preferably, a coil system is provided at each of two opposite sides of the lens holder.

Abstract: A hologram recording device that records a hologram by passing recording light and reference light through the same objective lens and irradiating a recording medium, includes: a light splitter for dividing light from a light source into the recording light and the reference light; a light combining member for combining the recording light and the reference light, which have been divided by the light splitter, so as to be coaxial, and causing these light beams to advance to the objective lens; first and second lenses, positioned on an optical paths of the recording light and reference light, between the light splitter and the light combining member; a first aperture that narrows the recording light which has passed through the first lens; and, a second aperture that narrows the reference light which has passed through the second lens, the first and second lenses being configured to have different optical magnifications.

Abstract: An optical disk device for recording/reproducing information on/from a multi-layer optical disk moves a light focusing point for several layers by one focus jump. The optical disk device includes a controller to detect a level of a focus error signal to change an output level of a focus drive signal, and the controller changes timing to change the output level of the focus drive signal based on the number of layers for the focus jump.

Abstract: An optical pickup device imparts different astigmatisms from each other to light fluxes in four light flux areas A through D formed around an optical axis of laser light, out of the laser light reflected on a disc. The optical pickup device also changes the propagating directions of the light fluxes in the light flux areas A through D to separate the light fluxes in the light flux areas A through D from each other. A signal light area where only signal light exists is defined on a detection surface of a photodetector. Sensing portions are arranged at a position corresponding to the signal light area. Accordingly, only the signal light is received by the sensing portions, thereby suppressing deterioration of a detection signal resulting from stray light.

Abstract: In an information recording medium including a substrate and an information layer having a recording layer, on and from which information is recorded and reproduced by laser beam application, the recording layer is made from a Te—O-MA-MB material consisting of Te, O, MA (wherein MA is at least one element selected from Au and Pd) and MB (wherein MB is at least one element selected from Ag, Cu and Ni) with a content of Te of 10 atom % to 50 atom %, the content of O of 40 atom % to 70 atom %, the content of MA of 3 atom % to 15 atom %, and the content of MB of 3 atom % to 15 atom %. This constitution provides a low-cost information recording medium which enables high-density recording and stable reproduction of recorded data for a long period of term.

Abstract: A laser driving device includes: a first pulse generating section; a second pulse generating section; a light emission waveform generating section; and a light emission level pattern storing section.

Abstract: Disclosed herein is a laser driving device including: a sample-hold section; a first pulse generating section; a second pulse generating section; a light emission waveform generating section; a storing section; and a sampling pulse generating section.

Abstract: In order to ensure a favorable recording characteristic for a write-once recording medium whose recording layer is made of an organic dye having an absorption spectrum at a wavelength ?=405 nm, this optical information recording apparatus includes a unit to set a write power to form recording marks, a space forming power to form spaces and a pulse width of a cooling pulse, and a unit to record information onto the recording medium according to the setting. The pulse width of the cooling pulse and a ratio of the space recording power to the write power are determined from a favorable region in a plane whose one coordinate axis represents the ratio and whose other coordinate axis represents the pulse width of the cooling pulse.

Abstract: An optical disk device for recording or reproducing an optical disk has: an objective lens for irradiating a laser beam to the optical disk; an actuator for moving the objective lens in the radial direction of the optical disk; and a spindle motor for rotating the optical disk. After the laser beam irradiated to the optical disk passed through a PID portion of the optical disk, the actuator moves the objective lens in the radial direction of the optical disk at a timing corresponding to a rotational speed. Between signals to drive the actuator, an output time of a deceleration signal is set to a predetermined ratio of a time during which an acceleration signal is outputted. While the deceleration signal is outputted, a light spot passes through the PID portion.

Abstract: An optical disc device is provided with an optical head (1) including a light source (21), a condensing optical system including an objective lens (28) for receiving a light beam emitted from the light source and forming a microspot on a multilayer optical recording medium, a photodetector (201) for receiving the light beam reflected by the multilayer optical recording medium and outputting an electrical signal corresponding to the amount of light and a coma aberration correcting element (26) for correcting a coma aberration of the condensing optical system, and a processing circuit (3) for controlling the condensing optical system and the coma aberration correcting element.

Abstract: Provided is an objective lens for an optical pickup apparatus. The objective lens collects diffracted light generated by an optical path difference giving structure onto the information recording surface of an optical information recording medium as a spot and suppresses fluctuation of diffraction efficiency due to a change of using wavelength. The optical pickup apparatus using such objective lens is also provided. The total diffraction efficiency can be improved by adjusting a wavelength at which the diffraction efficiencies of a plurality of basic structures forming the optical path difference giving structure in the objective lens are maximum, in accordance with a basic structure.

Abstract: A method and an apparatus for capturing encoded signals on a label surface. A pick-up head is utilized to detect all or predetermined codes on a control feature zone of a label surface of a Light Scribe disc so as to generate a sub-beam added signal. A calculation unit is used to calculate the average value of the sub-beam added signals. A dynamic slicer, which could dynamically set its standard value at a half of the average value of the sub-beam added signals, slices the sub-beam added signals and captures the encoded signals. A processor decodes the encoded signals and translates those into Light Scribe disc's information.

Abstract: An optical disc apparatus according to the present invention includes: a laser light source for emitting multiple light beams, of which the wavelengths are different from each other and include a first wavelength and a second wavelength that is longer than the first wavelength; an optical system for converging an arbitrarily selected one of the light beams on an optical disc that has a surface and at least one information storage layer; a focus control section for controlling the focus position of the light beam with respect to the optical disc; and a defect detecting section, which senses light reflected from the surface of the optical disc with the focus position of the light beam set on the surface, thereby determining, based on the intensity of the reflected light, whether or not there is a fingerprint on the optical disc.

Abstract: This invention allows super-resolution reproduction with which a better bER value is attainable, when information is recorded by a random pattern including a mark length not longer than a resolution limit, by use of a highly versatile signal decoding method. Information is recorded as marks and spaces coded by RLL(1,7) modulation, which each of the marks and spaces have one of a plurality of lengths, and 2T marks and 2T spaces of the marks and spaces being formed are shorter than 0.12 ?m. An information recording layer (20) includes a reproduction film (21) and a reflective film (22) which are provided in this order from a side from which reproducing light is incident, which reproduction film is made of (i) zinc oxide, (ii) strontium titanate, (iii) titanium oxide, (iv) cerium oxide, or (v) a material including at least one of the (i) through (iv), and which reflective film is made of tantalum or titanium.

Abstract: An optical data recording medium, in which irradiation of a light beam is used for recording and/or reproducing data includes (i) a substrate having an a rise and/or a recess which are a light-incident surface, (ii) a reflective layer, provided on the light-incident surface of the substrate, for reflecting the light beam, (iii) a light absorption layer for converting, to heat, a light of the light beam to heat on the surface of the reflective layer, (iv) a reproducing layer, provided on the surface of the heat-light converting layer, having a transmittance that changes in accordance with a light intensity distribution of the light beam. The optical data recording medium is excellent in super-resolution property, and enables reproduction of a shorter mark length.

Abstract: The present invention relates to a method for calibrating a focus position of an optical pick-up. The optical pick-up is located on a focus position at a preset distance from a recordable optical medium to emit a recording beam of a preset power to the recordable optical medium so that corresponding optical data are recorded in the recordable optical medium. The method includes: altering a focus position of the optical pick-up during a recording process to generate a corresponding write radio frequency (RF) signal; detecting a minimum value of the write RF signal and a corresponding object focus position; and moving the optical pick-up to the object focus position so that the optical pick-up performs recording at the object focus position in the recordable optical medium.

Abstract: According to the present invention, a recording film is partially initialized using a first light beam (A) having a wavelength for initialization, focus adjustment is performed using a second light beam (B) having a wavelength corresponding to a wavelength for recording and reproducing information on and from an information recording medium, and then the recording film is initialized using the first light beam (A), thereby it is possible to securely initialize recording films of all information layers of a multilayer information recording medium.

Abstract: The present invention realizes the emission of a high-output short-pulse beam and a reduction in power consumption. A laser control unit (2) of a short-pulse light-source device (1) raises a gate pulse (PG) of a gate signal (SG) supplied to a power supply circuit (5) in such a manner that the gate pulse (PG) rises only for the duration of an extremely short pulse width (T) to include the rise time of a generated pulse (PL) of a pulse signal (SL) supplied to a driving circuit (6). In this way, necessary power can be supplied at the rise timing of the generated pulse (PL), and the power consumption (Pa) can be greatly reduced from the standard power consumption (Pb).

Abstract: This invention allows super-resolution reproduction with which a better bER value is attainable, when information is recorded by a random pattern including a mark length not longer than a resolution limit, by use of a highly versatile signal decoding method. Information is recorded as marks and spaces coded by RLL(1,7) modulation, which each of the marks and spaces have one of a plurality of lengths, and 2T marks and 2T spaces of the marks and spaces being formed are shorter than 0.12 ?m. An information recording layer (20) includes a reproduction film (21) and a reflective film (22) which are provided in this order from a side from which reproducing light is incident, which reproduction film is made of (i) zinc oxide, (ii) strontium titanate, (iii) titanium oxide, (iv) cerium oxide, or (v) a material including at least one of the (i) through (iv), and which reflective film is made of tantalum or titanium.

Abstract: This invention allows super-resolution reproduction with which a better bER value is attainable, when information is recorded by a random pattern including a mark length not longer than a resolution limit, by use of a highly versatile signal decoding method. Information is recorded as marks and spaces coded by RLL(1,7) modulation, which each of the marks and spaces have one of a plurality of lengths, and 2T marks and 2T spaces of the marks and spaces being formed are shorter than 0.12 ?m. An information recording layer (20) includes a reproduction film (21) and a reflective film (22) which are provided in this order from a side from which reproducing light is incident, which reproduction film is made of (i) zinc oxide, (ii) strontium titanate, (iii) titanium oxide, (iv) cerium oxide, or (v) a material including at least one of the (i) through (iv), and which reflective film is made of tantalum or titanium.

Abstract: A lens unit, an optical system, a recording/playback apparatus and a method for recording to and/or reproducing from a recording medium to compensate for a spherical aberration and perform stable recording or reproduction of data in recording or reproducing data to or from a recording medium having a plurality of recording layers are disclosed. The lens unit includes a first lens for condensing light beams outputted from a light source to a recording medium, a second lens for increasing a numerical aperture of the first lens to form a near field, and a liquid crystal device for compensating for a spherical aberration included in the first lens and the second lens, thereby compensating for the spherical aberration.

Abstract: According to the present invention, multiple space bitmaps (SBMs #0 and #1 30) are provided for the user data area of each recording layer. A disc management structure update unit including one of those space bitmaps and a disc definition structure (TDDS 32) and having a size of one block is written on a management information area (TDMA 17). As a result, data including the disc definition structure (TDDS 32) can always be arranged in the first block at the top of the management information area (TDMA 17).