Abstract: An optical information recording apparatus can maintain a stable recording quality when recording information on an optical information recording medium having a recording layer of a multilayer structure. An optical information recording medium of a rotating type has a plurality of recording layers each having an information recording area in which information is recorded using a laser beam. An inner power calibration area is provided in each of the recording layers at a location closer to a center of rotation of the optical information recording medium than the information recording area, and is used to perform a test write in an optimum power control process to acquire an optimum recording power of the laser beam. The outer power calibration area is provided at a location farther from the center of rotation than the information recording area, and is used to perform a test write in an optimum power control process to acquire an optimum recording power of the laser beam.

Abstract: A data read/write device writes to or reads from an optical disc medium having thereon a plurality of areas in which management information is redundantly stored. Conditions for setting a read/write operation are indicated in third management information stored in the inner circumferential area. The pickup of the device performs the steps of: reading a first management information group from the inner circumferential area; retrieving a piece of third management information based on the corresponding valid address included in the first management information group; moving to the outer circumferential area and reading a second management information group; and if the update count of the second management information group is higher than that of the first management information group, retrieving a piece of third management information based on the corresponding valid address included in the second management information group.

Abstract: An information storage medium having a plurality of information storage layers, each of which includes an optimal power control (OPC) area for obtaining an optimal recording condition, wherein OPC areas in odd-numbered and even-numbered information storage layers are disposed not to face each other and not to contact each other, or partially overlap each other and lock out use of the overlapped portion. Therefore, when an OPC area of one information storage layer performs OPC, this OPC does not affect another information storage layer.

Abstract: A method for adjusting recording power is provided. The addresses of changing recording velocity and section pause points are set. Then, the recording power in the inner circle is tested with the lowest rate, and the recording power on each high rate area is estimated. A required record data is recorded. Afterwards, whether the recording of the required record data is completed is determined. If confirmed, the recording process is terminated; otherwise, whether the recording velocity needs to be changed is determined. If confirmed, the recording is paused to change the recording velocity, otherwise, the recording process continues. The recording of required record data continues according to the estimated recording power and the recording power is tested to obtain an optimum recording power. Next, the recording power is adjusted to the optimum recording power to continue recording the rest of required record data, so as to enhance the recording quality.

Abstract: An information record apparatus includes a recording device for recording information into a record medium, where pre-information for controlling a recording of the information is recorded in advance, by irradiating the record medium with a laser beam whose power is varied depending on a driving pulse; a first controlling device for modifying the driving pulse into at least a top pulse and a middle pulse; an optimum ratio detecting device for detecting an optimum ratio that is a pulse ratio at which a first reproduction quality that is a reproduction quality of the pre-information meets a first reference, on the basis of a first correlation information to indicate a correlation between the first reproduction quality and a pulse ratio of at least the top pulse to the middle pulse; and a second controlling device for modifying the driving pulse in accordance with a pulse ratio corresponding to the optimum ratio.

Abstract: A write strategy method, medium, and apparatus. The method includes writing a signal to a storage medium by using a predetermined power and an initial write strategy, calculating variation characteristics of a data signal which separately correspond to variations of write strategy parameters, if the written signal does not satisfy initial quality standards, and calculating correlations among periods of the data signal and correlations among the write strategy parameters by using the variation characteristics of the data signal, and determining the write strategy parameters based on the correlations among the periods of the data signal and the correlations among the write strategy parameters.

Abstract: According to one embodiment, a recording unit includes a recording unit for recording data on a recording medium, a laser light source for emitting a laser when data is recorded on the recording medium, a flash memory for storing a previously measured output characteristic of the laser light source, and a control unit for controlling the recording unit, wherein the recording unit comprises a selection unit which performs test writing on the recording medium, and selects an optimum laser power from a reproducing signal waveform of the written data when data is recorded on the recording medium, and the control unit comprises a correction unit which reads an output characteristic of the laser light source from the flash memory, and corrects a value of a reference laser power when the selection unit performs test writing.

Abstract: Provided is an optical disc apparatus including: an optical pickup configured to form marks and spaces on the optical disc by using a recording power and a erasing power respectively; a control unit configured to write test data on trial on the optical disc while changing the recording power and the erasing power and to determine an optimum recording power and an optimum erasing power; and a nonvolatile memory configured to store a correction coefficient which has been obtained in advance. The control unit corrects a power ratio of a recommended recording power to a recommended erasing power by the correction coefficient stored in the memory, and controls to write the test data on trial on the optical disc while changing the recording power and a erasing power, the erasing power being acquired from the recording power and the corrected power ratio.

Abstract: A first trial write process obtains an optimum recording power of a test pattern even with respect to data having different rules for the recording waveforms corresponding n type data length sets, and a second trial write process using this optimum recording power obtains optimum pulse width or optimum pulse edge position separately for each data length set. Based on the optimum recording power and optimum recording waveform obtained by these trial write processes, recording operation is performed so as to form all the data lengths with satisfactory accuracy, thereby making it possible to obtain a proper reproduced signal.

Abstract: There is provided an information recording and reproducing method and an apparatus for the same capable of optimizing the shift adjustment of a recording pulse recorded in an optical disk even at the time of recording information on the optical disk at a high speed. The shift adjustment value of the recording pulse optimized at a low speed recording on an optical disk is multiplied by a constant value to be taken as the optimum shift conditions of the recording pulse at the high speed recording.

Abstract: A method of and apparatus for recording data on an optical recording medium form a mark or a space by using a recording waveform having an erase pattern containing a multi-pulse. The method and the apparatus prevent distortion of the mark or the space and improve a mark shape such that a recording/reproducing characteristic of the optical recording medium is improved.

Abstract: A method for determining an optimum laser power for a recording medium. The method includes checking if a portion of an unused area in a test area on the recording medium is defective, and performing an optimum laser power operation in a used area in the test area, in which the used area is a non-defective area that was used to test the optimum laser power for the recording medium.

Abstract: An optical disc recording method includes: determining that an optical disc to be recorded is an optical disc including a recording layer comprising organic dye; and controlling a laser such that space formation power Ps necessary for space formation is equal to or smaller than bias power Pbw. In a case wherein the relation of Ps<Pbw is satisfied, the relation between the asymmetry value, ? value, and main power Pw includes substantial linearity. Accordingly, control of the main power Pw can be performed with the asymmetry value and ? value as evaluation indexes, and accordingly, disturbance or the like can be readily handled.

Abstract: An optical recording apparatus. A laser diode driver performs optimum power calibration according to a predetermined target value to obtain reference recording power, and adjusts the reference recording power to obtain testing recording power settings. A signal process device obtains recording qualities respectively in predetermined test regions of an optical storage medium corresponding to the reference recording power and the testing recording power settings. A processor obtains an optimum recording power according to the recording quality, obtains an optimum target value corresponding to the optimum recording power. The optimum target value is then used for data recording.

Abstract: The present invention relates to a method for controlling a dual-beam LBR (Laser Beam Recorder) (56) suitable for mastering a record carrier (60) by writing data in the record carrier in circular or spiral tracks and comprising: means (58) for rotating a record carrier; means (62) for moving a dual-beam laser (61) over the record carrier (60) in a radial direction with reference to the rotation of the record carrier (60); means (65) for controlling the dual-beam laser output power; and means (66) for synchronizing the rotation of the record carrier (60), the movement of the dual-beam laser (61) and the dual-beam laser output power. In accordance with the invention synchronizing the rotation of the record carrier 60; the movement of the dual-beam laser 61 and the dual-beam laser output power is performed such that at least a part of the data is written in at least one track comprising a different arrangement than circular or spiral.

Abstract: An information recording apparatus that records information with a substantially constant linear density in a circumferential direction of a recording medium having a disk shape, includes variable velocity recording control means, recording power modification means, recording power storage means, and initial recording power value setting means.

Abstract: A method for setting an optimum value of a write power level for use in an optical recording apparatus for writing information on a recording layer (3) of an optical recording medium (1) by means of a radiation beam (5) is described. The recording layer is able to change between an amorphous and a crystalline state. The apparatus comprises a radiation source (4) for emitting the radiation beam (5) having a controllable value of a write power level (Pw) for recording information on the recording medium, a control unit (12) for recording a series of test patterns in a test area on the recording layer, each pattern being recorded with a different value of the write power level, a read unit (90) for reading the patterns and forming corresponding read signal portions, and first means (10, 101, 102) for deriving a value of a read parameter from at least one read signal portion and setting an optimum value (Popt) of the write power level based on the values of this read parameter.

Abstract: In a recording method or apparatus, in order to set an optimal recording condition by a minimal number of times of testing, test recording is carried out while changing power and pulse width of recording pulses in a stepwise manner. Conditions for the test recording are concentrated in a region of a matrix defined by power×pulse width.

Abstract: A condition of a recording pulse comprising a top pulse and a following pulse is determined in a predetermined order. In some embodiments, an mT pulse condition is first determined by test recordings with various power and pulse conditions, involving an inspection of recording quality; then an m?T/(n?m)T ratio is determined by test recording under the mT pulse condition fixed; and finally an nT pulse is configured based on the ratio. A phase shift can be corrected by test recording with the nT pulse.

Abstract: An optical disk recording apparatus is designed for forming pits on a recording surface of an optical disk of a given type at a given recording speed by applying a laser light in the form of a sequence of multiple pulses obtained by intermittently turning on and off the laser light according to a given multi-pulse pattern. In the apparatus, a write strategy circuit is set with a pattern table and controls the turning on and off of the laser light according to a multi-pulse pattern selected from the pattern table in correspondence to a length of the pit to be formed. A storage section stores a plurality of pattern tables of different kinds, each pattern table containing a plurality of multi-pulse patterns corresponding to a plurality of lengths of the pit. A control section selects one of the pattern tables based on either of the recording speed and the type of the optical disk, and reads out the selected pattern table from the storage section and sets the read pattern table in the write strategy circuit.

Abstract: A method of determining a recording power used to record information to an optical disc, includes carrying out test recording which records predetermined data to a predetermined area of the optical disc to determine the recording power, and recording predetermined data with a power equal to or more than the determined recording power to an area adjacent to the predetermined area.

Abstract: When recording data on a multilayer optical disk, the recording power for a recording layer provided further from the laser beam incident side is optimized. An optical disk includes a first layer and a second layer. When recording data onto the second layer, the amount of return light at the space forming time is detected, and whether the first layer is in an unrecorded state or in a recorded state is determined in accordance with the level of the amount of return light. Then, the recording power for the second layer is changed in accordance with the determination result regarding the unrecorded/recorded state of the first layer. If the transmittance of the first layer decreases as a result of data recording, the recording power for the second layer in a case where the first layer is in the recorded state is set greater than the recording power for the second layer in a case where the first layer is in the unrecorded state.

Abstract: In a method and apparatus for generating optimum write power, a control unit controls a write voltage generating unit to generate sequentially write voltages of different levels to drive an optical read/write head to generate different write powers so as to write data on a plurality of write intervals of an optical recording medium in sequence. Simultaneously, a detecting and computing circuit detects a peak value, a first level and a second level of a write reflected signal generated by each write interval for computation so as to obtain a first control parameter of each write interval, and detects a peak value, a bottom value and a direct current level of a read reflected signal generated during reading of each write interval for computation so as to obtain a second control parameter of each write interval, thereby generating an optimum write power based on optimal first and second control parameters.

Abstract: A method for setting recording power of recording light, capable of an appropriate setting for a multilayer optical recording medium. The recording power of the recording light for an information recording layer of the multilayer optical recording medium to be irradiated with, is set by: evaluating an information recording layer to be evaluated for recording power when all the information recording layer(s) lying closer to a light incident surface than the information recording layer to be evaluated does is/are in a low transmittance state; evaluating the information recording layer to be evaluated for recording power when all the information recording layer(s) lying closer to the light incident surface than the information recording layer to be evaluated does is/are in a high transmittance state; and determining ground information for setting recording power, based on these values of the recording power.

Abstract: An information recording medium (100) is provided with: a first recording layer (L0 layer) having a first calibration area (103-1) in which test information for calibrating a power of laser light in recording record information can be recorded; and a second recording layer (L1 layer) having a second calibration area (103-2) in which the test information can be recorded and in which at least one portion of a recording area faces the first calibration area, wherein the first calibration area and the second calibration area including a space area (103U-1, 103U-2) having a predetermined size in positions facing each other, the test information is recorded in a recording area (103R-1) located on one side, centered on the space area, in the first calibration area, and the test information is recorded in a recording area (103R-2) located on other side which is opposite to the one side, centered on the space area, in the second calibration area.

Abstract: Provided are a method and apparatus for performing a writing test using charge pumps in an optical disk reproducing/recording apparatus. In the apparatus for performing the writing test, an optimum power control (OPC) determining unit determines a phase of a radio frequency signal using a reference voltage, and generates a corresponding OPC voltage; an analog-to-digital converter (ADC) unit converts the OPC voltage into a digital signal; and a micom controls a power control unit according to the digital signal, to appropriately control laser power.

Abstract: In an optical disk system using a PRML identification system, a method for deriving an optimum recording wave in a short period of time is provided. Parameters of the recording wave are adjusted by using an evaluation value obtained by a signal evaluation method which is suitable for the PRML identification system as an index. In this case, as a parameter adjusting method, a plurality of adjusting methods are utilized.

Abstract: The present invention sets forth a method and a system for calibrating optimized power of an optical pick-up unit of an optical disk drive. The system comprises a micro-processor, and a signal processor. The micro-processor coupled to the optical pick-up unit sets an initial power corresponding to an optical disk, and calculates a predetermined number of power levels to cover the range of the initial power for performing a recording procedure. The signal processor coupled to the micro-processor determines whether a servo state failed during optimized power calibration, and calculates recording performance of each power level. The signal processor transmits the servo state and the recording performance to the micro-processor for determining the optimized power.

Abstract: Recording information is disclosed in which an information recording medium is irradiated with a recording energy beam that is power-modulated into at least a record power level and a record-ready power level lower than the record power level. The information is recorded on the recording medium in the form of length and interval of a mark portion. When forming a mark portion of a predetermined length, the radiation energy of the energy beam is increased as compared with when forming a mark portion of a different length before or after the first pulse of an energy beam pulse train including at least a pulse for forming the mark portion.

Abstract: An information storage medium having a plurality of information storage layers, each of which includes an optimal power control (OPC) area for obtaining an optimal recording condition, wherein OPC areas in odd-numbered and even-numbered information storage layers are disposed not to face each other and not to contact each other, or partially overlap each other and lock out use of the overlapped portion. Therefore, when an OPC area of one information storage layer performs OPC, this OPC does not affect another information storage layer.

Abstract: A recording power row P(i) is selected and a signal is recorded in a recording test region of an optical disk, while shifting a recording power, to detect a reproduced signal amplitude row m(i) that corresponds to the recording power row P(i). The relation of the recording power row P(i) and the row of multiplication products P(i)×m(i) is linearly approximated and the intersection of the linear approximation straight line and the recording power axis is computationally determined as recording threshold power Pthr, for at least three recording power rows Pj(i) that are centered at Pf(j) in the recording power row P(i) within a defined range. Then, the recording power Pt(j) is computed as a multiplication product of the recording threshold power Pthr(j) and a factor ? contained in the disk information, for each recording power row Pj(i). Finally, the optimum recording power Pwopt is computationally determined according to the at least three recording powers Pt(j).

Abstract: An optical disk, which has a storage area is disclosed. Data is recorded and reproduced by emitting laser light into the storage area on the optical disk Power condition information and recording write strategy information which correspond to recording speed information for recording and reproducing data are recorded. The recording speed information is indicative of constant linear velocity and different linear velocity from the constant linear velocity.

Abstract: In a method for recording information on an information recording medium having a data recording area for storing user data and a test area used for test recording by a recording apparatus, it is detected whether the test area is unusable when executing the test recording. The test recording is executed in the test area when the test area is detected not to be unusable, or executed in the data recording area when detected to be unusable. Management information relating to the test recording executed in the data recording area is recorded in a predetermined area. Hence, it is possible to eliminate a limit of number of times of test recording which depends on the size of the test recording area.

Abstract: Various systems, methods, and programs embodied on a computer-readable medium are provided for calibrating a laser power in an optical disc drive. In one embodiment, a range of reflectivity of an optical disc in the optical disc drive is established. A calibration pattern of marked segments is written to the optical disc and the reflectivity of the marked segments is measured. An average reflectivity is generated for each one of a plurality of laser power settings within the range of reflectivity, thereby obtaining a curve that depicts the average reflectivity with respect to the laser power settings. The laser power setting at a knee of the curve is identified and a slope of the curve at a position on the curve where the average reflectivity decreases as the laser power settings increase is determined. The laser power setting is calculated that results in a predefined darkness based upon the laser power setting at the knee and based upon the slope.

Abstract: A recording method for an optical disc having at least three recording layers (11, 12, 13, 14), in which test recording areas are formed in the odd-numbered recording layers (11, 13) and the even-numbered recording layers (12, 14) in positions that are mutually non-overlapping in the thickness direction of the optical disc, the test recording areas in the odd-numbered recording layers are formed in positions mutually aligned in the thickness direction, and the test recording areas in the even-numbered recording layers are formed in positions mutually aligned in the thickness direction. The time for test recording for determining the optimal recording power can be shortened.

Abstract: A recording and reproducing method, wherein, on recording and reproduction of a recordable DVD medium, which has a recording layer containing an organic dye on a substrate having a guide groove with wobble, wherein linear velocity conditions for CLV recording is recorded on the substrate, recording starts at a linear velocity less than a highest linear velocity at the innermost circumference; when the linear velocity is switched over to the highest linear velocity on the way, a comparison is made between an optimum recording power of Po at the highest recording velocity that is temporarily optimized by test-writing in a power measurement area at the outermost circumference and an optimum recording power of Pi at the highest linear velocity that is recorded in the substrate; in the case of Po>Pi, a value given by the formula of “(Po+Pi)/2+(Po?Pi)2Pi” is employed as a recording power with which recording starts at the highest linear velocity; and in the case of Po?Pi, Pi is employed.

Abstract: A method for reproducing data according to the present invention is adapted for reproducing data recorded in an optical recording disc including a multi-layered body formed by forming a decomposition reaction layer containing noble metal oxide as a primary component and a light absorption layer so as to sandwich a dielectric layer therebetween by irradiating a laser beam onto the optical recording disc and forming a recording mark train including at least one of a recording mark having a length shorter than a resolution limit and a blank region having a length shorter than the resolution limit therein, and is constituted by changing the read power Pr of the laser beam in accordance with a readout linear velocity at which data are to be reproduced from the optical recording disc.

Abstract: A recording device for recording data on a rewritable optical record carrier (11). The device comprises recording means (21, 22, 25) for forming marks on the record carrier during recording operations by irradiating the record carrier with a radiation beam (24), the marks representing the data. Further, the device comprises control means (20) for controlling the recording operations and beam control means (31) for controlling a write power of the radiation beam with reference to an optimum write power by changing the write power within a predetermined write power range around the optimum write power for subsequent write cycles, each of the write cycles comprising at least one recording operation. Variation of the write power improves the overwrite quality, in particular, in the management area, such as the file system area.

Abstract: An information storage medium and an apparatus for recording and/or reproducing the information storage medium are provided to control optimal recording power without an influence of an optimal power control (OPC) area in a layer upon an OPC area in a different layer. The information storage medium includes at least one information storage layer including an optimal power control area for obtaining an optical recording condition. OPC areas in adjacent information storage layers are disposed within different radiuses of the information storage medium. Accordingly, even when the information storage medium is made eccentric or has a manufacturing error, a recording property of the information storage medium is prevented from being degraded due to an influence of an OPC area in an information storage layer upon an OPC area in an adjacent information storage layer.

Abstract: A method for optimizing write parameters of an optical storage medium is provided. The method is adapted for a recording device using the optical storage medium. The method includes loading the optical storage medium having a test area into the recording device, determining a combination of an original write strategy and an original write power according to the optical storage medium, writing test data into the test area with the combination of the original write strategy and the original write power for dynamically adjusting the combination of the original write strategy and the original write power to obtain a combination of an optimal write strategy and an optimal write power, and writing data into the optical storage medium with the combination of the optimal write strategy and the optimal write power.

Abstract: A processing method of an optical disc recording/playback signal includes: measuring a length of a first mark of a predetermined coding length which appears immediately following a shortest space recorded on the optical disc; measuring a length of a second mark which appears immediately following a longest space recorded on the optical disc and which has the same coding length as the first mark; and calculating a heat interference amount based on a difference of the measured length of the first mark and the measured length of the second mark. The method may further include specifying a laser power at a time of forming a space or a cooling pulse width, according to the heat interference amount.

Abstract: An optical disc on which information can be recorded by recording light has a first recording layer (102) and a second recording layer (103) disposed behind the first recording layer as viewed by the recording light; the first recording layer and the second recording layer have respective power adjustment areas (P1, P2) that are used to adjust the power of the recording light to the optimal recording power at the time of recording of information on each recording layer; a prewrite area (PW) is provided in correspondence to the power adjustment area (P2) used for optimal power adjustment in the second recording layer and restricted areas (A1, A2) on both sides of that power adjustment area (P2). The restricted areas (A1, A2) allow for the diameter of the recording light beam and for lamination misalignment. This configuration enables stable test recording to be carried out in a short time on an optical disc having multiple recording layers.

Abstract: A method for correctly determining optimum recording power through detecting whether a radio frequency (RF) top channel signal is correct, including determining a certain location for performing optimum power control (OPC) by checking a counter area in a power calibration area (PCA) in an optical recording medium, and recording an eight to fourteen modulation signal (EFM) in a test area in the PCA, performing analog/digital sampling with respect to an RF top channel signal and an RF bottom channel signal which are generated while reading test data repeatedly recorded in the PCA in regular sequence, and checking a noise level of the sampled RF top channel signal, and when the noise level of the RF top channel signal is greater than a preset reference value, determining that an error has occurred in detecting the optimum recording power to therefore abandon a certain area in the PCA wherein the OPC is being performed, and re-performing the OPC in a new area.

Abstract: The present invention provides a method and apparatus for optimizing optical disc writing strategy. The method for optimizing optical disc writing strategy comprises the steps of obtaining the information concerning whether said area to be written has experienced any writing before; searching for an area that has the corresponding information in the writing optimization area on said optical disc; and performing writing test on said area that has the corresponding information to optimize and determine an optical disc writing strategy for writing said optical disc. The method and apparatus could not only reduce the difference between the optical disc writing strategy and the real optical disc writing condition as much as possible, but also lower the requirement on the optical disc writing equipment and the cost, and could be easily realized.

Abstract: A laser power which is lower than an optimum reproduction laser power is set as an initial value. The reproduction laser power is increased from the initial value while trial reproduction is performed until a quality level of a reproduction signal is not lower than a reference level. At the time the quality level of the reproduction signal is not lower than the reference level, the reproduction laser power is set as the reproduction laser power with respect to an optical disk which is of a reproduction target.

Abstract: The present invention discloses a method of adjusting writing parameters, comprising the steps of testing a region to be written in a re-writeable optical disc without changing writing power level; calculating writing parameters in the region to be written based on the tested result; and adjusting writing parameters based on the calculated result. According to embodiments of the present invention, the direct over writing compatibility problem can be resolved. Moreover, power level adjusting is kept unchanged so as to avoid possible damage to direct over writing cycleability.

Abstract: An information recording device comprising a recording unit that records recording information by applying a laser beam to an information recording medium having a first recording layer for recording recording information by being irradiated with a laser beam and a second recording layer for recording recording information by irradiating with a laser beam via the first recording layer, a calculating unit that calculates an optimum laser beam power when, by using the recording means, trial-recording trial information is recorded by irradiating the second recording layer with a laser beam via a recording-information-unrecorded recording area in the first recording layer and recording information is recorded by irradiating the second recording layer with a laser beam via a recording-information-recorded recording area in the first recording layer, and a control unit that controls the recording unit.

Abstract: A method for determining a read power of a laser beam includes a step of setting a power of a laser beam to a recommended recording power Pw? and forming a recording mark train including at least one of a recording mark having a length shorter than a resolution limit and a blank region having a length shorter than the resolution limit in an optical recording disc, thereby recording test data therein. The method also includes a step of setting the power of the laser beam to a recommended read power Pr? and reproducing the test data recorded in the optical recording disc, a step of judging whether or not signal characteristics of a reproduced signal obtained by reproducing the test data satisfies reference conditions, and determining an optimum read power of the laser beam based on the result of the judgment.

Abstract: An optical memory device records and reproduces information by forming marks and lands in an optical information recording medium.

Abstract: An optical recording device includes an optical pickup, an asymmetry detection circuit, and a microcomputer. The optical pickup corrects an aberration of an object lens based on an aberration correction value using a liquid crystal panel in the optical pickup, irradiates a laser beam of multiple stages of recording powers on an optical disk to form marks, and then reproduces the formed marks with a reproduction power. The asymmetry detection circuit detects amplitudes of RF signals of the marks reproduced by the optical pickup, calculates amplitude central values such that asymmetry takes a predetermined value, and determines an optimum recording power. The microcomputer performs spherical aberration correction to change a spherical aberration correction value from an initial value such that the optimum recording power takes a minimum value.