Abstract: Disclosed herein is a hard disk apparatus, including: a magnetic recording medium; a recording head adapted to record information on the magnetic recording medium; a semiconductor laser adapted to be controlled for light emission in a cycle of a recording clock to irradiate a light spot upon the magnetic recording medium to carry out thermal assistance in magnetic recording by the recording head; a laser driving circuit adapted to drive the semiconductor laser at a timing and with optical power in accordance with a light emission timing signal and a laser power controlling signal; and a controller adapted to set laser power in accordance with at least one of characteristics of the magnetic recording medium, semiconductor laser and recording head and output the laser power controlling signal to the laser driving circuit so that the laser power is adaptively varied.

Abstract: According to the present invention, heat generation amount control information for controlling a heat generation amount of a heat generating section (20) is arranged to correspond to each of temperatures so that a predetermined heat generation amount is obtained at each of the temperatures. The present invention includes a first computing section (41) that controls the heat generation amount of the heat generating section (20) according to the heat generation amount control information that is arranged in advance to correspond to temperature information that is obtained from a temperature sensor (13). This easily makes it possible to appropriately carry out at least either recording or reproduction with respect to a magnetic recording medium.

Abstract: Methods and devices for optimized ridge near field apertures for thermally assisted magnetic recording are disclosed. The aperture dimensions and supporting dielectric materials are optimized for maximum energy absorption at the magnetic recording layer for a light source having a wavelength of 780 nm, which can be produced by low cost laser diodes.

Abstract: Changes in the thermal boundary condition near a close point of an ABS to a media indicate proximity of the ABS with the media. Before contact, heat conduction from the ABS is primarily through convective and/or ballistic heat transfer to air between the ABS and the media. After contact, heat flux primarily flows from the ABS to the media through solid-solid conductive contact. Further, a light source within a HAMR transducer head may create additional thermal variations within the transducer head. These thermal variations create temperature variations within the transducer head. Two resistance temperature sensors on the transducer head at varying distances from the close point and/or light source measure these temperature variations. A temperature difference between the two resistance temperature sensors indicates proximity of the close point to the media and/or light output.

Abstract: In accordance with certain embodiments, an apparatus has a depletion-mode transistor electrically connected to a laser diode. The transistor provides a low impedance path for diverting electrostatic current away from the laser diode. In accordance with certain embodiments, a method for protecting a laser diode from an electrostatic charge includes providing a transistor that is electrically connected to a laser diode and has a drain and a source. The method further includes redirecting the electrostatic charge through a low impedance path from the drain to the source during a powered-on state.

Abstract: A light source unit includes a light source and a photodetector. The light source has an emission part for emitting light. The photodetector has a light receiving surface for receiving the light emitted from the emission part, and detects the light. The light source unit further includes a grating made of metal and disposed to extend along the light receiving surface. The grating includes a plurality of line-shaped portions that each extend in a direction intersecting the direction of travel of the light and that are located at positions different from each other along the direction of travel of the light.

Abstract: In an optical disk recording apparatus, a monitor monitors a recording power of a laser light. A laser control circuit enables a laser diode to perform test recording while using the monitor to monitor the recording power of the laser light and while controlling a laser drive voltage, so that the monitored recording power reaches a given reference value during the test recording. A voltage measurement section measures the laser drive voltage when the recording power of the laser light reaches the reference value. A calculation section calculates an initial laser drive voltage from the reference value of the recording power and the measured laser drive voltage corresponding to the reference value. A main controller allows the laser control circuit to set the calculated initial laser drive voltage and to start the recording while supplying the laser control circuit with the target value so that an actual recording power of the laser light promptly reaches the target value during the course of the recording.

Abstract: A hard disk drive includes a recording medium and a thermally assisted type magnetic head. The controller determines one output current of a photodiode as a first saturated output current, the one output current being defined where temperature measured by a temperature sensor is a first temperature and where signal-to-noise-ratio (SNR) of the reproducing signal current of the reproducing element is saturated with respect to an increase in output current of the photodiode, and another output current of the photodiode as a second saturated output current, the another output current being defined where temperature measured by the temperature sensor is a second temperature, which is different from the first temperature, and where SNR of the reproducing signal current of the reproducing element is saturated with respect to an increase in the output current of the photodiode.

Abstract: An information recording apparatus includes a medium for recording information; a head slider including a device for writing the information onto the medium and a reflective surface for reflecting light; a light emitting portion for generating emission light toward the reflective surface; a light receiving portion for detecting light reflected on the reflective surface; and a regulating mechanism for adjusting an amount of the emission light from the light emitting portion in a mode of information recording onto the medium in correspondence to a result of the detection.

Abstract: A current gain control system is described and comprises first and second gain blocks respectively associated with the first and second input channels, wherein first and second gain blocks transmit first and second gain signals in response to receiving first and second input signals; first and second converters adapted to be respectively coupled to the first and second gain blocks, the first and second converters operative for setting gains associated with the first and second input channel and for transmitting first and second converted signals in response to receiving the first and second gain signals; and first and second switches for selectively coupling the first and second converters to first and second channel drivers, respectively, wherein the first and second channel drivers transmit channel gain signals in response to receiving the first converted signal, and the channel gain signal allows control of the gain associated with the input channel.

Abstract: In an information recording/reproducing method performing a thermo-magnetic recording, a tracking offset value of a recording light spot and/or a tracking offset value of a magnetic flux detecting element is changed in accordance with a radial position at which a tracking is performed at the present time, to make a direction of a magnetic wall of a recording magnetic domain in accord with a longitudinal direction of the magnetic flux detecting element. Alternatively, a shape of a heated area is changed to be in accord with the direction of the magnetic flux detecting means at respective radial position, to make the direction of the magnetic wall of the recording magnetic domain in accord with the longitudinal direction of the magnetic flux detecting element.

Abstract: On a host computer (300), writing software for controlling recording and image forming operations of an optical disc recording apparatus (10) is installed. When the writing software is activated, the host computer (300) requests the user to input various settings relating to record information and image information before giving instructions for starting recording and those for starting image formation to the optical disc recording apparatus (10), and, in accordance with various settings which are input in response to the request, determines the recording and image forming operations of the optical disc recording apparatus (10).

Abstract: An apparatus includes a slider including an air bearing surface and a waveguide configured to receive light from a light source, a sensor positioned to receive a portion of light emitted by the light source prior to the light exiting the slider at the air bearing surface, and a controller controlling the light source power in response to a characteristic of the sensor.

Abstract: Apparatus and method for light source power control during the writing of data to a storage medium. In accordance with various embodiments, a data recording head is provided having a magnetic transducer and a light source. The light source is driven at a first power level to irradiate an adjacent storage medium prior to the writing if data to the medium using the magnetic transducer. The first power level is insufficient to alter a magnetization state of the medium. The light source is subsequently transitioned to a higher, second power level to irradiate the storage medium during the writing of data to said medium using the magnetic transducer, the second power level being sufficient to alter said magnetization state of the medium.

Abstract: A reading devices suppresses deterioration of the recording marks caused by increasing the output laser power to compensate for a drop in the S/N ratio when reading at a high speed information recorded to a high density recording medium. To read information recorded to an optical data recording medium that is written and read using a laser beam output from a semiconductor laser, the reading method modulates a high frequency current on the drive current of the semiconductor laser to output the laser beam, and changes the light modulation rate according to the selected linear velocity used for reading. The light modulation rate is the ratio Pp/Pave between the peak power Pp and the average read power Pave of the light intensity of the high frequency modulated laser beam.

Abstract: A method for estimating maximum available write power of an optical storage drive includes generating a beam of laser light having a power level, measuring a first parameter of the laser light source and a second parameter of the beam of laser light, and using the measured parameters to estimate the maximum available write power.

Abstract: To reduce background light generated in a circumference of a scatterer in a head for a thermally assisted magnetic recording device using a scatterer having conductivity as an optical near-field generating element, a coil for generating a magnetic field is placed on a bottom portion of a slider, and an optical near-field generating element is placed in an inside of the coil. At this time, an inner diameter of the coil is set not larger than a wavelength of incident light, an interval between leader lines each for conducting an electric current to the coil is set not larger than a half of the wavelength of the light, and the coil for generating the magnetic field is caused to function as a shield for suppressing the background light.

Abstract: A data readout method is disclosed that is able to read data from an optical disk capable of super resolution readout with high accuracy. The data readout method allows reading data recorded in an optical disk by irradiating a laser beam onto the optical disk. The method includes the steps of varying a light emission power level of the laser beam while the laser beam is irradiated onto the optical disk, and acquiring a reflectivity of the optical disk corresponding to each light emission power level; calculating a second derivative of a curve representing correlation between the reflectivity and the light emission power with respect to the light emission power; calculating an extreme value of the second derivative; and calculating an optimum readout power level for super resolution readout based on the extreme value.

Abstract: The present invention relates generally to the storage of information on magnetic and/or optical storage media by using one or more novel approaches alone or in combination. These novel approaches are capable of using at least one code which may comprise more than two values (i.e., more than a “0” and a “1”). A first series of approaches for the storage of information applies generally to optical storage/retrieval systems (e.g., CD's, DVD's, etc.); while a second series of approaches applies generally to electric and/or magnetic storage/retrieval systems (e.g., magnetic, magneto-optic, etc.). Each series of approaches is capable of storing information in one or more codes, wherein such approaches permit, if desired, the use of at least one higher order code which is different from the traditional binary code of “0's” and “1's” currently utilized for the storage of digital information.

Abstract: Systems and methods for calibrating laser write power in a digital media drive are disclosed. The method includes writing to a calibration portion on a digital media labeling layer with energy from a laser. The writing includes using at least two different laser power settings within the calibration portion. The method also includes measuring a parameter in the calibration segment, the parameter being indicative of the reflectivity of the labeling layer, and determining a calibrated laser write power setting based on the measured parameter and the at least two different laser write power settings.

Abstract: An optical beam control device that can suppress deterioration of a laser diode and a photosensitive member is disclosed. Control is performed in such a manner that the luminous energy of emitted light is increased gradually in an initial period from the activation of a laser diode until the first generation of a BD detection signal. The initial period includes an extinction period in which the laser beam is extinguished. Therefore, deterioration of the light-emitting portion of the laser diode and the photosensitive member can be suppressed.

Abstract: In an information recording/reproducing method performing a thermo-magnetic recording, a tracking offset value of a recording light spot and/or a tracking offset value of a magnetic flux detecting element is changed in accordance with a radial position at which a tracking is performed at the present time, to make a direction of a magnetic wall of a recording magnetic domain in accord with a longitudinal direction of the magnetic flux detecting element. Alternatively, a shape of a heated area is changed to be in accord with the direction of the magnetic flux detecting means at respective radial position, to make the direction of the magnetic wall of the recording magnetic domain in accord with the longitudinal direction of the magnetic flux detecting element.

Abstract: The present invention proposes a method of controlling the laser power of a semiconductor laser that, in this method of controlling the laser power of a semiconductor laser by applying a power source voltage to between the collector and emitter of an output transistor and a serial circuit of the output transistor and a semiconductor laser, enables decreasing the power consumption of the output transistor. The present invention is arranged to apply a variable power source voltage Vcc to a serial circuit of an output transistor (Qb) and a semiconductor laser (SL) and thereby control the variable power source voltage Vcc such that a difference between the variable power source voltage Vcc and the peak hold voltage of an operating voltage of the semiconductor laser (SL) becomes substantially constant.

Abstract: Recording is started in an INC mode at the time of start of initial data recording (step S1). Next, it is determined whether recording onto an unrecorded region is possible in the INC mode (step S2). If it is determined that the recording is impossible, next, temp lead-out is recorded at a last portion of a recording region (step S4). Then, a recording mode for format 2 RMD is changed (step S5). Next, format 3 RMD is newly created, and is recorded in RMD in a management region (step S6). Then, the recording is restarted in a ROW mode (step S7).

Abstract: Provided is an optical recording method for recoding information on a phase-change optical recording medium at a low linear velocity by use of a divided pulse method. When forming a plurality of recording marks by use of a constant divided pulse number m, a light irradiation time period of recording light for recording a recording mark having a time length of nT is divided in the order of {?1T, ?1T, ?2T, ?2T, . . . , ?iT, ?iT, . . . , ?mT, ?mT} (in which m is a natural number representing a divided pulse number, ?i (1?i?m) is a real number greater than 0, ?i (1?i?m?1) is a real number greater than 0, and ?m is a real number equal to or above 0).

Abstract: Laser power adjustment is performed using a power calibration area (PCA) until the PCA is used up. After the PCA is used up, an additional PCA is reserved at the next recording start position and laser power adjustment is performed using the additional PCA. When an additional PCA is reserved, the additional PCA exists between an information file recorded this time and the last one of information files recorded previously in terms of a physical format. However, information test-written into the additional PCA is not regarded as an information file and PMA information is generated only from the information file recorded this time by excluding the test-written information. As a result, a situation is obtained in which the additional PCA does not logically exist on the disk and there will never occur an inconvenient situation where the additional PCA is erroneously reproduced at the time of reproduction.

Abstract: A light emitting device calibration system includes a device under test including a light emitting device to be calibrated and a microprocessor electrically coupled to the light emitting device. A light detector is coupled to the device under test. During a calibration mode, the microprocessor controls power of the light emitting device by changing values of a drive signal to the light emitting device, receives a power indication corresponding to light emitted by the light emitting device, and determines a power relationship relating values of the drive signal to powers of the light emitting device according to a power indication for each of a plurality of values of the drive signal. The light detector coupled to the device under test detects the light emitted by the light emitting device to generate the power indication corresponding to the light emitted by the light emitting device.

Abstract: If regeneration is not performed normally when data is regenerated from a medium, a read retry processing unit changes the intensities of the laser beam and of the regeneration magnetic field respectively to prearranged stages to perform the regeneration again. A regeneration condition change unit remembers the regeneration sector number for one read command from the higher order. When retry occurs, the regeneration condition change unit counts the number of the sectors for each stage which can be regenerated at each stage, and by providing a coefficient for each stage in advance, changes the default regeneration condition using the sum of products of the coefficients and the number of the counted regenerable sectors.

Abstract: The present invention relates generally to the storage and/or retrieval of information on magnetic storage media by using one or more novel approaches alone or in combination. These novel approaches are capable of using at least one code which may comprise more than two values (i.e., more than a “0” and a “1”). A series of approaches applies generally to existing electric and/or magnetic storage/retrieval systems (e.g., magnetic, magneto-optic, etc.) as well as other novel electrical/magnetic systems. Each series of approaches is capable of storing information in one or more codes, wherein such approaches permit, if desired, the use of at least one higher order code which is different from the traditional binary code of “0's” and “1's” currently utilized for the storage of digital information.

Abstract: The invention relates generally to store information on magnetic or optical storage media by using one or more novel approaches alone or in combination. These novel approaches are capable of using at least one code which may comprise more than two values (FIG. 4d, 43). A first series of approaches for the storage of information applies generally to optical recording and reproducing system (FIGS. 7-10, optical media 66), while a second series of approaches applies generally to electric or magnetic recording and reproducing systems (FIG. 1-2, magnetic medium 1), Each series of approaches is capable of storing information data in one or more codes (FIG. 4d, 42a, 42b, 42c, 42d) and the use of at least one higher order code which is different from the traditional binary code of “0” and “1”.

Abstract: It is an object of the present invention to provide an information recording and reproducing technique capable of improving the reliability of information recorded on a recording medium. A recording condition comprising amplitude information and the ratio of the amplitude to the recording power is previously recorded on the recording medium. Using this previously recorded information, information is recorded and then immediately reproduced to calculate the optimum recording power from the amplitude information obtained from the reproduced signal. By adapting the recording condition accordingly, it is possible to secure reliability of information in performance.

Abstract: The present invention provides an optical information reproducing method of detecting a record mark formed in an optical information recording medium and generating a reproduced signal, comprising the steps of: detecting a mark length of each record mark on basis of a reproduced signal, and correcting the reproduced signal by a correction amount corresponding to the detected mark length, and an optical information reproducing apparatus for detecting a record mark formed in an optical information recording medium and generating a reproduced signal, comprising: a detection circuit for detecting a mark length of each record mark on basis of a reproduced signal, and a correction circuit for correcting the reproduced signal by a correction amount corresponding to the detected mark length.

Abstract: It is an object of the present invention to provide a method for recording information in an optical recording medium with a good direct overwriting characteristic. The method for recording information in an optical recording medium according to the present invention forms record marks in a recording layer containing a phase change material by modulating the power of a laser beam between a plurality of power levels including a recording power Pw, an erasing power Pe and ground power Pb. The erasing power Pe is set to a level within a region where a reflection coefficient of a region between neighboring record marks approaches a reflection coefficient of the record mark as the erasing power Pe increases. As a result, a good overwriting characteristic can be obtained when data are recorded at a high linear velocity.

Abstract: A disk recording-playback device including a laser drive circuit for feeding a drive signal to an optical head and adjusting the power of a laser beam irradiated by the optical head, an error correcting circuit for detecting an error rate of a reproduced signal, and a system controller for controlling operation of the laser drive circuit for signal reproduction and signal recording based on the output of the error correcting circuit. The system controller successively sets the laser powers to at least three different values, obtains evaluation data for each laser power, approximates the relationships between the laser powers and the evaluation data to a quadratic curve, whereby an optimum laser power is derived corresponding to a vertex of the quadratic curve. Accordingly the optimum reproduction power and recording power are set, to thereby record and reproduce signals with high accuracy.

Abstract: A device that records information on an optical disc and a method for recording the information on the optical disc, so as to maintain a constant recording quality when the information is recorded on the optical disc using a constant number of the rotations to control the speed. The recording device includes a linear velocity detector detects a linear velocity which is a velocity of a spot of a light, which is irradiated to record the information on a surface of the optical disc, in a tangential direction of a circumference of the optical disc, and an optical power controller controlling the optical power of the light to record the information on the surface of the optical disc based on the linear velocity detected by the linear velocity detector.

Abstract: A magneto-optical storage medium that protects against the effects of cross-talk, making it possible to further reduce the level of track density, and which also makes it possible to conduct high-density recording/playback with a reduced magnetic field for erasure and a favorable level of playback signal quality. More specifically, a magneto-optical storage medium, which includes at least the following laminated layers, in the following order: a playback layer, a non-magnetic layer, a transfer layer, a cut-off layer, and a recording layer. The playback layer preferably displays easy in-plane magnetization characteristics within the monolayer at room temperature, and the transfer layer and the recording layer each have easy magnetization characteristics in the vertical direction of the monolayers at room temperature when each layer is considered as a monolayer.

Abstract: An optical storage device decreases the influence of return light to the laser light source and prevents an increase of power consumption even if high frequency superimposing is performed. The optical storage device applies drive current, to which a high frequency signal is superimposed, to the laser light source, and reads/writes data from/in the storage medium. The high frequency superimposing is set to OFF as a default to save power consumption, and high frequency superimposing is turned ON only when it is judged that servo is unstable, and high frequency superimposing is turned OFF when it is judged that servo is stable.

Abstract: In a magneto-optical disk drive using a domain wall moving magneto-optical recording medium, a test-writing operation adjustment to deal wit dynamic fluctuation factors is minimized, and a reproducing or recording laser power is automatically optimized. A power of a light beam by which a domain wall starts to move is detected, and a power of a laser used to reproduce or record an information is corrected based on a change in the domain wall movement starting power. As the domain wall movement starting power, it is possible to use, for example, when the power of a light beam is varied, such a power as to maximize a rate of change of the amplitude of a reproducing signal.

Abstract: An optical disk device for writing information on an optical disk having an APC part for monitored driving of a laser diode is provided which performs first and second OPCs. An unused partition of a test area and reference power value are read out from the optical disk. APC is turned off if the recording speed exceeds 1×. A first optimum writing power value is obtained by writing on the unused partition by driving the laser diode at a plurality of first test laser power values centered on the reference power value and reading out the information. APC is turned on if the recording speed exceeds 1×. A second optimum writing power value is obtained by writing on a subsequent unused partition by driving the laser diode at a plurality of second test laser power values centered on the first optimum writing power value and reading out the information.

Abstract: A method and system for optimizing energy consumption during data read/write operations in a disk-based memory system is provided. The method includes the steps of reading a data clip length, Ls and determining an available energy-optimum recordable track segment.

Abstract: The present invention provides a high precision, low cost laser power calibration system. First, the photo signals output from a standard photo diode are received by a photo calibration system; then a set of standards consisting of the corresponding current signals and the power signals are saved in an EEPROM. Finally, the photo diode to be calibrated can be calibrated using the present system in accordance with the calibration standards.

Abstract: The present invention relates to a method, an apparatus and a record carrier for controlling radiation power and/or field strength during a reading operation from a magneto-optical recording medium comprising a storage layer and a read-out layer. An expanded domain leading to a pulse in a reading signal is generated in said read-out layer by copying a mark region from said storage layer to said read-out layer upon heating by said radiation power and by applying an external magnetic field. A pulse pattern in the reading signal is analyzed. The analyzing result is compared with run length characteristics of the data stored in said storage layer. The radiation power and/or the magnetic field strength are controlled on the basis of the comparison result. Thus, much less or no disc capacity has to be reserved for radiation power and/or magnetic field calibration, since the user data can be used for this purpose.

Abstract: An optical disk drive has a pick-up head for generating a laser beam to record data on an optical disk and for detecting corresponding power of the laser beam, and a power control unit for adjusting power of the laser beam generated by the pick-up head. The power control method includes inputting a plurality of first control signals into the power control unit in order so that the power control unit generates a plurality of first control voltages related to the first control signals for sequentially driving the pick-up head to output a plurality of first test powers, and using the plurality of first test powers and the plurality of first control signals to establish a first mapping function. The optical disk drive uses the first mapping function to get a first predetermined output power and a corresponding first predetermined control signal according to the first mapping function.

Abstract: A phase error detection apparatus and method is disclosed whereby a data signal is played back at a high S/N ratio from a magneto-optical disk making use of a ghost signal by magnetic domain wall displacement detection while the playback laser poser is kept at an optimum level. First, the laser power is controlled so that the time delay of a ghost signal from a data signal may be equal to a fixed multiple of a data detection clock. Thereupon, a laser power control section searches for a point at which the amount of jitters generated is small based on a RF signal. Then, the playback laser power is adjusted so that the time delay amount of the ghost signal from the data signal may be the fixed multiple n=5 of the clock nearest to the phase delay amount set in advance of a ghost which appears in the isothermal region with a laser power with which an optimum signal characteristic is obtained.

Abstract: A reproducing laser output can be adjusted to an optimal level. To this end, a magneto-optical disk device includes a differential amplifier and a shortest recording mark identifier that detects a shortest recording mark reproducing signal corresponding to a component of a shortest recording mark in a reproducing signal obtained by reproducing a magneto-optical disk. In addition, an envelope detector detects an amplitude level of the shortest recording mark reproducing signal, a comparator compares the amplitude level with a reference voltage outputted from the reference voltage source, and a drive control section adjusts the reproducing laser beam to an output level at which the amplitude level is equal to or higher than the reference voltage, based on a comparison result from the comparator.

Abstract: A magneto-optical disk recording and reproducing device, which carries out recording and reproducing for a magnetic super-resolution magneto-optical disk including a recording layer and reproducing layer, has a recording data processing circuit which records long recording marks at different positions between adjacent tracks in a radius direction, each of the long recording marks being larger in diameter than an aperture formed on the reproducing layer by projecting thereon the light beam. According to this arrangement, it is possible to continuously reproduce a data recording area with high accuracy and optimum reproducing power without being affected by adjacent tracks.

Abstract: A power controller is provided which can control the emission power from a light source to follow an appropriate response property based on a target value. The power controller includes feedforward systems for allowing currents corresponding to target values set at target value setting units to be switched at a switching device and supplied as a power setting current to an adder. Also included are feedback systems for detecting the power of the laser beam emitted by a semiconductor laser serving as the light source and adjusting a feedback current to stabilize the deviation from the target values at a predetermined value. Further included are a switching device for allowing the target values to be switched and supplied to the aforementioned feedback systems, and the adder for adding a feedback current and the power setting current to thereby generate a drive current for driving the semiconductor laser.

Abstract: A recording medium for use with an information recording apparatus which has a timing adjusting controller to adjust a timing of a recording pulse having a disk-like substrate. At least one track is provided on the disk-like substrate and a zone is provided which includes the at least one track. The zone stores information relating to a predetermined timing of a pulse for the recording medium which is detected by the apparatus.

Abstract: A technique for determining the recording medium temperature, thereby enabling high track density in Hybrid recording. This allows compensation for changes in the ambient temperature and variations in the laser power over its life. Such a temperature measuring technique also enables laser power shaping of the spot size/thermal contour in the medium, providing smaller spot size definition with a given optical system. Baseline modulation is a sensitive probe of the temperature gradient between a magneto-resistive read element (anisotropic or giant) and the surface of a disk. By calibrating the temperature rise (above ambient) of the read element, this technique can be used to determine the disk surface temperature.

Abstract: An amplitude detection circuit detects the peak value of an output signal of a photo-detector amplified by a head amplifier. The peak value detected by the amplitude detection circuit is read into a drive controller, and compared with a target value suitable for coding in a binary format a detected signal. The gain of a variable gain amplifier is adjusted accordingly. Consequently, an analog signal processing circuit can stably codify the detected signal in a binary format. Under the control of the drive controller, a recording power level calculation circuit determines a test writing power level with which test writing is performed on a test track of a magneto-optical disk. The recording power level calculation circuit then calculates an actual record power for each zone of the magneto-optical disk according to the test writing power level.