Abstract: A method of adjusting a write strategy of a recordable disc comprises steps of: generating a test pattern on a power calibrating area of the recordable disc according to a first write strategy and a first write power; establishing a Pit-to-Land Inter-Symbol Interference table and a Land-to-Pit Inter-Symbol Interference table by measuring a plurality of Pits and Lands with different time lengths in the test pattern; and generating a second timing parameter set by adjusting a first timing parameter set of the first write strategy according to the Pit-to-Land Inter-Symbol Interference table and the Land-to-Pit Inter-Symbol Interference table.

Abstract: An 11T single signal and a 3T single signal are recorded on a DVD?RW at the optimum recording power P1 and a recording power P2 of an intensity of 85% with relative to the optimum recording power P1, and then these signals are reproduced to calculate asymmetry values A1 and A2. If a difference (A1-A2) between both asymmetry values is equal to or greater than a reference value of 0.05, it is judged that a method using the asymmetry value is available for the OPC, and if the difference is less than a reference value of 0.05, it is judged that the method is not available. Then, the judgment result is recorded on the DVD?RW as a flag. A DVD drive judges whether or not the asymmetry value is used for the OPC on the basis of the flag.

Abstract: In summary, the present invention provides a method for estimating maximum available write power of an optical storage drive. Optical drives have a certain guaranteed maximum power corresponding to the largest emission angles and worst case electrical parameters of the laser, but many drives could produce more if needed because they are not worst case. The extra power that is available from the lasers that is not worst case is wasted. By identifying drives with lasers that have favorable parameters, the maximum available write power of a drive becomes larger. The present invention solves this problem by providing an estimation method wherein a beam of laser light is generated having a power level (P), a first parameter of the laser light source and a second parameter of the beam of laser light that is generated are measured and used to estimate the maximum available write power.

Abstract: An optical storage system includes an optical pickup unit movable across an optical medium. The optical pickup unit has a light detector, a laser diode, and a laser driver signal processor circuit. The laser driver signal processor circuit includes a detected signal processing block for outputting read signals corresponding to light received at the light detector, and a read signal processing block for processing the read signals and generating control signals or synthesis signals according to the read signals. A control unit is coupled to the optical pickup unit for controlling the optical pickup unit and decoding data recovered from the optical medium.

Abstract: In an optical disk apparatus and a method for determining the recording power for the same, for determining the optimum value of a laser power when recording data onto a high density optical disk, a test signal is recorded with changing the recording power Pw while fixing an erasing power Pe. Reproduction is made on the signal recorded so as to obtain a “?” value indicative of asymmetry of the reproduction signal to each the recording power. In this instance, the “?” value, or the optimal recording power Pwo is determined, with utilizing an area or region, being called APC region, which is provided in a part of the recording regions, which are divided into a large number thereof, each being made of a predetermined information recording unit (RUB), being unique to that disk, and further equalization thereof. Herein, the erasing power Pe to be fixed is determined from a result of measurement on a modulation factor, “M” value while recoding another test signal.

Abstract: An optical information recording method records information with respect to an optical information recording medium having a multi-layer structure recording layer formed by a plurality of recording layers each capable of recording information, and carries out an Optimum Power Control (OPC) prior to carrying out the recording. Recording conditions that are used when carrying out the OPC are read from one of the recording layers of the optical information recording medium to which the recording is to be made, where each of the recording layers is recorded with the recording conditions therefor, and the OPC is carried out using the read recording conditions.

Abstract: According to one embodiment, in a data write operation, the average value of the emission power detected by a front monitor is obtained via a low-pass filter and a sample hold circuit. In the write operation, erase power controlled by an erase APC is obtained via a sample hold circuit. While an LD is emitting light with the erase power, an erase current is determined from the output voltage of the erase APC. On the basis of the average power, the erase power, the erase current, and a waveform of the recording pulse, a current-to-emission-power characteristic of the LD is estimated. Furthermore, on the basis of the current-to-emission-power characteristic, the peak power in the write operation of the LD are controlled.

Abstract: An information storage medium on which data is recorded after performing optimum power control (OPC) and a method and apparatus to record/reproduce data on/from the information storage medium, wherein the recordable information storage medium has a plurality of recording layers and a pickup irradiates a beam onto the information storage medium, utilize operations of: recording data on at least a portion of a recording layer through which a test beam to find an optimum recording power passes before performing optimum power control (OPC) on a desired recording layer and performing OPC on the desired recording layer. The method and apparatus allow data to be recorded after performing a test to determine an optimum recording power, thus providing effective recording/reproducing quality.

Abstract: An information storage medium on which data is recorded after performing optimum power control (OPC) and a method and apparatus to record/reproduce data on/from the information storage medium, wherein the recordable information storage medium has a plurality of recording layers and a pickup irradiates a beam onto the information storage medium, utilize operations of: recording data on at least a portion of a recording layer through which a test beam to find an optimum recording power passes before performing optimum power control (OPC) on a desired recording layer and performing OPC on the desired recording layer. The method and apparatus allow data to be recorded after performing a test to determine an optimum recording power, thus providing effective recording/reproducing quality.

Abstract: An information storage medium on which data is recorded after performing optimum power control (OPC) and a method and apparatus to record/reproduce data on/from the information storage medium, wherein the recordable information storage medium has a plurality of recording layers and a pickup irradiates a beam onto the information storage medium, utilize operations of: recording data on at least a portion of a recording layer through which a test beam to find an optimum recording power passes before performing optimum power control (OPC) on a desired recording layer and performing OPC on the desired recording layer. The method and apparatus allow data to be recorded after performing a test to determine an optimum recording power, thus providing effective recording/reproducing quality.

Abstract: A reproducing position control circuit has a reading part for reading data stored in a recording medium, a position information detecting part for detecting the position information of data read by said reading part within said recording medium, and a control part for storing said position information detected by said position information detecting part in a volatile memory, and retrieving said position information within said volatile memory to store it in a writable non-volatile memory when the power is turned off or after a predetermined time passes since the power is turned off.

Abstract: An optical disc recording device according to the present invention is capable of quickly performing the OPC operation for a rewritable optical disc, and is also capable of setting the proper writing power for both an unwritten area and a written area. A microcomputer reads out, from a memory, preliminary writing conditions for the optical disc in question, and then performs preliminary writing so that data is written to a test writing area of the optical disc under the preliminary writing conditions. After that, test writing to the test writing area, which has been subjected to the preliminary writing, is performed with the writing power being changed, and thereby the optimum writing power is determined. Information about the writing power and the erasing power is stored in the memory on an optical disc type basis. The information is used for the preliminary writing.

Abstract: An apparatus, and related method, for recording data that includes a controller to generate control information required to record a main data. The control information including at least one information unit for a specific writing speed and recording layer. The information unit includes write strategy parameters for first write strategy type to be used for the writing speed and recording layer, the first write strategy type being one of an (n?1) write strategy type and an n/2 write strategy type, where n is a length of mark and each type represents a number of write pulse to form a corresponding mark. A writing/reading unit records the control information at a specific area of a recording medium, wherein the controller controls the writing/reading unit to record the control information and to record the main data on the recording layer using write strategy parameters for the first write strategy type included in the information unit, at the specific writing speed.

Abstract: A laser diode drive circuit for an optical disc recording and/or reproducing apparatus includes a plurality of laser diodes to output laser beams having different wavelengths, a switch circuit for selectively connecting a required laser diode from a plurality of laser diodes, a laser diode drive power supply circuit for driving the laser diode selectively connected by the switch circuit, a photodiode for detecting at least part of laser beams emitted from the laser diode to convert a detected part of laser beams into an electrical signal, a plurality of current-to-voltage conversion amplifiers connected to an output of the photodiode and whose conversion resistance values can be adjusted and having differently designed center conversion resistance values and an automatic power control circuit connected to outputs of the current-to-voltage conversion amplifiers to output a feedback signal to the laser diode drive power supply circuit.

Abstract: A recording apparatus (200) is provided with: a recording device (351) for recording record information with a variable recording power; a recording control device (354) for controlling the recording device to record the record information to be adjacent to an unrecorded portion; a power controlling device (361) for controlling the recording power such that the recording power in recording the record information which is recorded adjacent to the unrecorded portion is weaker than the recording power in recording the record information other than the record information which is recorded adjacent to the unrecorded portion; and an overwrite controlling device (362) for controlling the recording device to overwrite the recorded portion adjacent to the unrecorded portion with overwrite information in which a ratio of presence of a mark signal component is smaller than a ratio of presence of a space signal component.

Abstract: A laser power control apparatus is for use in an optical disk apparatus for recording information on an optical disk having at least a first layer and a second layer. The laser power control apparatus includes a power control section for controlling a laser element such that a power of a laser beam approaches a control target level; a change detection section for detecting that a recording condition for the optical disk has been changed; and a power adjustment section for adjusting the power of the laser beam for a recording film of the first layer, in accordance with an output from the change detection section. The power adjustment section determines the power of the laser beam for a recording film of the second layer, based on the power of the laser beam which has been adjusted for the recording film of the first layer.

Abstract: Prior to recording operation of an optical disc, OPC is performed three times so as to obtain optimal recording powers. By averaging the obtained optimal recording powers, an optimal recording power that is used for recording operation is obtained. More specifically, recording operation is performed continuously with respect to three continuous regions (16-18) each of which includes 10 sectors, and then reading operation is performed continuously with respect to the three regions (16-18). Then, by averaging results obtained from the three regions (16-18), an optimal recording power is obtained, which is adapted to characteristics of the disc.

Abstract: An optimal power calibration method includes steps of: performing a first optimal power calibration procedure at a first power calibration area with a first recording speed to obtain a first optimal power level corresponding to the first recording speed; performing a second optimal power calibration procedure at a second power calibration area with a second recording speed to obtain a second optimal power level corresponding to the second recording speed, the second recording speed being higher than the first recording speed; and determining an optimal recording power level for recording data on a disc at a predetermined speed based on the first optimal power level and the second optimal power level.

Abstract: There has been an issue that the operation of a semiconductor circuit performing edge timing control cannot follow up in the multipulse generation process where high multiplication of speed progresses every year. A light strategy drive comprises a control register (22) storing timing edge information for generating the edge of a recording waveform signal, a PLL (23) generating a clock for generating the edge of a recording waveform signal, and a timing control circuit (24) for receiving timing edge information corresponding to the recording waveform signal from the control register (22) to output timing edge information having a predetermined amount of delay in parallel and compounding the edges based on the timing edge information outputted in parallel. Timing edge can be controlled with high precision even at the time of high speed operation, and a high precision multipulse can be generated.

Abstract: The present invention sets forth a power saving method and a power saving system applied in an optical disk drive. The power saving system comprises a central processing unit, a spindle motor, an optical pick-up unit, an analog portion of control circuits and a digital portion of control circuits. Each of the analog or digital portions of control circuits can be divided into several sets of circuits. Each set of circuits is coupled to an associated operation mode of the optical disk drive. The power saving system further comprises a power controlling unit for differentiating the specific sets of circuits not being used in the specific operation mode and powering them down. The sets of circuits not being used will be powered up while the associated operation mode in which they are required to operate is nearly started. The present invention also provides a power saving method of powering down the sets of circuits not being used relative to a specific operation mode of the optical disk drive.

Abstract: The invention relates to methods and devices for forming marks and lands by applying a radiation beam (32) to a recording surface (301) of an optical record carrier (30). Recording strategies are proposed for recording information at high recording speeds. An intermediate power level (P1, P2) is introduced in between the bottom power level (P0) and the write power level (Pw), its value being dependent on the length of the preceding land (151, 152, 153). A raised write power level (PR1, PR2) is also proposed, its value being dependent on the length of the mark to be recorded (241, 242, 243).

Abstract: An information recording apparatus is provided with: a recording device for recording information into recording areas of an information recording medium by irradiating laser light; a reference-output-value holding device for holding a reference-output-value of the laser light for recording the information into the recording areas; an estimating device for estimating an output value of the laser light which was irradiated in the past in an already-recorded-area in which the information is already recorded; and a controlling device for controlling said recording device to irradiate the laser light onto the already-recorded-area with an output value larger than the reference output value if the estimated output value is larger than the reference output value.

Abstract: A high-density optical recording medium and method of recording data on the optical recording medium. The optical recording medium includes a plurality of data recording/reproducing surfaces having reflectances for light passing through a pit area, a land/groove area, and a land/groove area on which data are recorded, of a data recording/reproducing surface included between a light source for emitting light and a recording/reproducing surface selected from the plurality of data recording/reproducing surfaces, the reflectances satisfy the expressions r1?r2?r3 and {(r1?r3)/r1}?0.2, where r1, r2 and r3 are the reflectances of the pit area, the land/groove area and the land groove area on which data are recorded, respectively.

Abstract: An optical recording medium has a phase-change recording layer containing Sb and Te as essential elements therefor, to which is added at least one element selected from the group consisting of Ag, Au, Cu, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, N, P, Bi, La, Ce, Gd, and Tb, the recording layer being capable of assuming an amorphous phase changed from a crystalline phase by the application of a laser beam thereto, thereby optically recording information. Recording marks are formed in the recording medium by converting a light emission wave of laser beam into a recording pulse train comprising a plurality of on-pulses and off-pulses, with a recording frequency being continuously changed corresponding to the location of each of the recording marks in the radial direction of said recording medium. A recording apparatus has laser beam driving circuit means, signal generation means, and signal transmission means for achieving the above recording method.

Abstract: The present invention relates to a method of optimizing the write power for recording marks in an information layer of a record carrier by irradiating the information layer with a (pulsed) radiation beam, said information layer having a phase that is reversibly changeable between a first (for example a crystal) phase and a second (for example an amorphous) phase. Since the methods known for 1 T write strategies generally cannot be used for nT write strategies, n being an integer greater than 1, a new method is proposed comprising the steps of: recording (S 1) a pattern of test marks including short marks having a predetermined short nominal runlength onto the record carrier by applying at least three different write powers, measuring (S2) the runlengths of said recorded short marks obtained by applying the at least three different write powers, and determining (S4) an optimum write power on the basis of the deviations of the measured runlengths from the nominal runlength of said short marks.

Abstract: The invention relates to a method and a device for recording an information signal 10 in a phase change layer of a recording medium. A mark is recorded by a sequence 13 of write pulses and previous marks between the marks to be recorded are erased by a sequence of erase pulses 14. De bias power level 191, 192 between the erase pulses is made dependent on the recording speed, thus obtaining low jitter of the recorded marks and at the same time preventing thermal cross write during erase.

Abstract: A recording condition determining method is disclosed for realizing high quality recording at high speed while preventing the degradation of a light source. Specifically, a determination is made as to whether an optimal recording power obtained through OPC or running OPC exceeds a predetermined threshold value, and if it is determined that the optimal recording power exceeds the threshold value, a choice is selected out of multiple choices including the choice of not changing the optimal recording power based on a predetermined selection criterion. Then, a recording condition is established based on the selected choice. By setting the selection criterion so that the choice of not changing the optimal recording power is selected when damage to the light source is expected to be minimal, recording may be performed without lowering the recording speed even when the optimal recording power exceeds the threshold value.

Abstract: A power calibrating method includes steps of: determining a target value for a front monitor diode signal; outputting light with a power having a writing power level and an erasing power level, durations of the writing power level being identical to durations of the erasing power level; obtaining multiple values of the front monitor diode signal and an average of the multiple values of the front monitor diode signal; and adjusting the writing power level until the average of the multiple values of the FMD signal equals to the target value.

Abstract: An information recording method includes the steps of carrying out an experimental write on both inner-peripheral and outer-peripheral experimental writing areas, in the case of the outer-peripheral experimental writing, a constant recording power computed on the basis of the optimum recording power is used, which is estimated by the inner-peripheral experimental writing, in addition, an optical disk apparatus operates according to this information recording method, thereby removing the fluctuation factors of the disk.

Abstract: An optical disk apparatus for suppressing a Digital Sum Value (DSV) and performing Running Optimum Power Control (R-OPC). An encoding/decoding circuit inserts a synchronization information item to a head of only one synchronous frame when data are recorded on an optical disk. First, the encoding/decoding circuit inserts a synchronization information item having a polarity of either a mark or a space on the basis of a DSV. When the polarity of the first synchronization information item is a mark, the polarity of a next synchronization information item is set to a space. When the polarity of the first synchronization information is a space, the polarity of the next synchronization information is set to a mark. A system controller executes R-OPC at a timing when the synchronization information having the polarity of a mark is recorded on the optical disk.

Abstract: An optical pickup includes a light source which emits light, a grating which separates a portion of the light emitted from the light source, a reflecting member which reflects another portion of the light emitted from the light source, a monitoring photodetector disposed on a traveling path of the light reflected from the reflecting member and which measures the reflected light, an optical path changer which changes an optical path of the light separated by the grating, an objective lens light which condenses the light the optical path of which is changed onto a disc, and a signal detecting photodetector which receives the light reflected from the disc.

Abstract: A method for manufacturing an optical disc apparatus including: reading by an optical pickup head a medium on which signals are recorded with appropriate optical power; leading an RF signal corresponding to the recorded signal obtained from the medium by the reading by the optical pickup head to a ? value calculation circuit and calculating a ? value; and storing the calculated ? value as a circuit offset into a circuit offset storage section, and an optical disc apparatus thus manufactured are disclosed.

Abstract: An optical-disk drive device is provided which is capable of executing recording or reproduction at a plurality of numerical apertures and keeping constant the quantity of light which is emitted by a light-emitting element.

Abstract: A method of recording writing speed information and per writing speed write strategy information within disc control information is provided. The standardized disc control information can be uniformly applied to efficiently cope with the record/playback of the optical disc. In configuring disc control information within a management area of an optical disc including at least one recording layer, the method includes steps of providing the at least one disc control information within the management area, the disc control information provided per applicable writing speed to each of the at least one recording layer; and recording applicable recording speed information within the disc control information.

Abstract: In a recording material, physical characteristic information of the recording medium, and more specifically, material information representing the material of the disc, is recorded. Accordingly, a recording apparatus and a reading apparatus easily and accurately determine the physical characteristics of the disc, thereby making it possible to provide suitable setting for performing an operation.

Abstract: A write adjustment method adjusts recording power, recording time, and recording position of a recorder. The recorder includes a light detecting chip to receive a reflected light signal and generate a recording detection signal to a high pass filter. The high pass filter receives the recording detection signal and outputs a filtering signal. The write adjustment method includes writing first short period data to a disk, acquiring a reference voltage of the high pass filter according to a maximum value and a minimum value of the filtering signal, writing first mixing period data to the disk according to a plurality of predetermined recording times, acquiring a first maximum value and a first minimum value according to the filtering signal and adjusting and determining a first recording power of the recorder when a target value is achieved according to the first maximum value, the first minimum value and the reference voltage of the high pass filter.

Abstract: A laser diode drive control apparatus and method in an optical storage medium recording/reproducing system.

Abstract: For providing a method for conducting a real-time compensation on the recording power during that verify process, and also for providing an optical disk apparatus for achieving the high-speed recording of information and the high quality, by adopting such the method therein, the method for compensating a recording power of an optical disk apparatus, for recording/reproducing information onto/from an optical disk 100, which forms a track made of spiral-like land and groove on a information recording surface thereof, and is executed with a verify process for a defect block within a user data recording area thereof, wherein when executing a verify process, error information of data, which is written by a light irradiated from an optical pickup 200, is obtained from a reproduced signal, which is reproduced from said optical pickup, and an intensity of the light irradiated from a laser light source of said optical pickup, upon basis of a ? value, which is obtained by a ? value detecting means 240, as well as, the

Abstract: Disclosed herein is an information recording/reproducing apparatus that includes a first and a second recording/reproducing modules, a buffer memory to store information temporally, and a control module that switches between a first mode and a second mode when the information is dubbed from the first recording/reproducing module to the second recording/reproducing module. In the first mode, information in the first recording/reproducing module is reproduced and stored in the buffer memory. In the second mode, the information stored in the buffer memory is recorded in the second recording/reproducing module. The apparatus further includes a temperature detecting module. Depending on the temperature detected by this module, the apparatus changes the movement of the second recording/reproducing module in the first mode and the movement of the first recording/reproducing module in the second mode.

Abstract: A control data area of an optical disc holds correction information for correcting a recording laser power Pmax determined by performing trial writing. The recording laser power Pmax determined by trial writing is corrected on the basis of the correction information stored in the control data area, thereby setting a recording laser power Popt used for making a recording.

Abstract: A method of recording data on an optical disc including a preceding recording layer and a following recording layer capable of having data recorded thereon. The method includes recording data on the preceding recording layer, assigning a weight, to which a difference in recording sensitivities of the preceding and following recording layers of the optical disc is applied, to an OPC (Optimum Power Calibration or Optimum Power Control) recording power of the following recording layer, and determining a starting recording power of the following recording layer, such that data is recorded in the following recording layer, and applying a laser beam having a specific power equal to the starting recording power of the following recording layer to the following recording layer, and recording data on the following recording layer.

Abstract: The amount of light reflected from a disk is detected, and it is determined according to the amount of reflected light whether the disk is a recordable disk or a rewritable disk. The disk is controlled according to the result of determination such that it is rotated at a constant angular velocity (CAV) or at a constant linear velocity (CLV) and recording is executed. Further, rotation driving control of the disk is selected according to factors other than the type of the disk, such as according to whether random recording is allowed or not, according to a recording state in the disk, according to whether an alternative area is provided or not, according to a recording start position, or according to whether initialization is required or not. CLV control or CAV control is appropriately selected for a disk at recording to suppress a reduction in accessibility and a reduction in data transmission rate.

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: Optical pick-up units and laser drivers are disclosed, which can be used in various types of information recording/reproducing apparatuses, such as, but not limited to, DVD and CD drives, DVD camcorders, and DVD video recorders. A laser driver integrated circuit (LDIC) includes an automatic power controller, a running optical power controller, and a write strategy generator. The LDIC can be part of a chip-set, to be located on an optical pick-up unit (OPU). The chip-set can also include a power monitor integrated circuit (PMIC) to monitor the laser diode, and a photo-detector integrated circuit (PDIC) to detect light produced by the laser diode. The PMIC and the PDIC each include their own offset, gain and sample-and-hold circuitry.

Abstract: In an optical disc in/from which data is recorded or reproduced by irradiating a storage area on the optical disc with a laser, information containing recording velocity information (RVI) for recording/reproduction, which represents a linear velocity different from the standard linear velocity, and write strategy information (WSI) corresponding to the recording velocity information is stored in a land pre-pit or the like on the optical disc.

Abstract: A method of and apparatus for setting optimum recording power using characteristic values calculated inversely from recording power that allows a recordable optical disc to have a minimum value of jitter. The method includes setting a first optimum recording power value using characteristic values of an RF signal detected from an optical disc, and recording a predetermined pattern on the optical disc while changing the first recording power value; measuring a value of jitter according to the recorded pattern, and setting a recording power value when a minimum value of jitter is obtained as a second optimum recording power value; inversely calculating the characteristic values from the second optimum recording power value; and setting a third optimum recording power value using the inversely calculated characteristic values.

Abstract: A method and apparatus for recording data on an optical disk calculates an optical power at a first recording speed, compares the calculated optical power to a predetermined value, and then determines whether to apply the first recording speed based on a result of the comparison. The optical power at the first recording speed is calculated based on a reference optical power and a measured optical power, and the predetermined value may correspond to the maximum allowable power of a laser pickup. The method and apparatus may be used to control the speeding, timing, and/power of a data recording operation, as well as to compensate for temperature variations and/or power margins of one or more circuits in an optical disk device.

Abstract: The present invention provides a flexible power interface control system and a method of the same capable of flexibly changing the LDD setting for complying with different controlling states or different write strategies. The different controlling states or write strategies may be used for different disk types or different writing modes. The flexible LDD setting in accordance with the present invention is contributing to improve the recording performance and stability of an optical disk drive for complying with various disk types or different writing modes.

Abstract: According to one embodiment, single-sided dual-layer recordable disc 100 may be used. Information recording is performed by forming mark and space portions on data area DA using modulated laser power. Pp denotes the maximum laser power or peak power for forming the mark portion, and Pb denotes the bias power for forming the space portion. Power ratio Pb/Pp is calculated for each of recording layers L0 and L1. Information is recorded on any of the recording layers L0 and L1 based on the result of calculation. Here, the calculated power ratio Pb/Pp changes among the recording layers L0 and L1, thereby optimizing the recording condition for a multi-layer recordable optical disc within relatively short time.

Abstract: A laser power control apparatus for controlling the output power of a semiconductor laser used to record and reproduce data in and from a recording medium is provided. The laser power control apparatus includes a controller configured to vary the peak output power level of the semiconductor laser in a stepwise manner, calculate a differential efficiency at each of the varied peak output power levels, and determine a laser driving current based on a relation between the differential efficiency and the peak output power level. In addition, a laser driving unit is configured to drive the semiconductor laser using the laser driving current determined by the controller.