Abstract: An optical pickup calibrating apparatus for calibrating the laser emitting direction of an optical pickup supported on a guiding rod is provided. The optical pickup calibrating apparatus has a base and a holder. The holder, which is pivotally assembled to the base, has a trench formed on a sidewall thereof and encircling the holder. The latitude of the trench is uneven. The guiding rod has a first end slidably assembled in the trench. The rotation of the holder results a motion of the first end perpendicular to the base for adjusting the tilt of the guiding rod.

Abstract: There is provided an optical disc recording/reproduction device capable of accurately performing the focus offset and spherical aberration correction even for an optical disc having no data recorded. The optical disc recording/reproduction device includes: an optical pickup having a spherical aberration corrector for correcting the spherical aberration of an objective lens; and various control units; and can generate a tracking error signal (TE) at least by a push-pull signal by the push-pull method. When an optical disc mounted is in an unrecorded state, the spherical aberration correction amount and the objective lens focus offset amount are adjusted according to the push-pull signal, predetermined data is recorded on the optical disc, and the reproduction signal obtained by the data is used to adjust the spherical aberration correction amount in the spherical aberration corrector of the optical pickup and the focus offset amount of the objective lens.

Abstract: A method for generating a calibration value for a tracking error signal in an optical disc drive comprises the steps of performing a plurality of N jumps towards respective target tracks of an optical disc inserted in said optical disc drive; in each jump, calculating a one-jump normalization value; calculating a multi-jump calibration value on the basis of the plurality of N one jump normalization values obtained from the respective jumps. A control signal for controlling the radial actuator of the optical disc drive is generated on the basis of a normalized tracking error signal, which is calculated on the basis of the tracking error signal and the multi jump calibration value.

Abstract: An apparatus according to the present invention includes a write compensation section, which generates a write signal to write information on an information storage medium, and a writing section for irradiating the information storage medium with a pulsed beam based on the write signal generated by the write compensation section. The information storage medium includes a recording layer, which has an optical constant that changes continuously with the total quantity of light received. The writing section radiates and condenses multiple pulsed beams on the recording layer at an interval that is shorter than the diameter of the pulsed beams on the recording layer. The write compensation section generates the write signal such that the each sum of variations in the optical constant at each irradiated spot of the pulsed beam on the recording layer through the end of a write operation forms a predetermined variation pattern.

Abstract: A method and system for removing periodic disturbances pertaining to turntable and spindle motor errors during recording of a blank optical information carrier. The periodic disturbances are determined in advance and removed only during recording by a repetitive control/learning feedforward control circuit (88).

Abstract: There is provided a disk recording apparatus capable of minimizing a servo error and recording in the last zone at the maximum one of the recording speeds specified in the apparatus or disk recording medium even if the disk recording medium is in poor condition. At any position during disk activation, an axial-run-out and eccentricity measuring circuit (115) measures the eccentricity of the disk recording medium. A CPU (101) calculates the upper-limit rotation speed from the measurement, divides the recording area into zones in such a manner that the disk recording medium rotates at speeds lower or equal to the upper-limit rotation speed, determines the maximum one of the recording speeds specified in the apparatus and supported by the disk recording medium for each zone, sets a zone CLV table, and stores the table in a RAM (102). Then, the recording speeds are changed at zone boundaries according to the zone CLV table set based on the upper-limit rotation speeds calculated from the eccentricities.

Abstract: An information carrier apparatus for accessing an information carrier having at least one track formed therein includes a times crossed detection section for detecting the number of times that a head structured to access the information carrier has crossed the track; an eccentricity direction detection section for detecting an eccentricity direction of the information carrier based on the number of times; an eccentricity distance detection section for detecting an eccentricity distance of the information carrier based on the eccentricity direction and the number of times; and an eccentricity correction section for correcting eccentricity of the information carrier based on the eccentricity direction and the eccentricity distance.

Abstract: A method and an apparatus of adjusting the tilt-angle of the lens in the optical pick-up head. The apparatus includes a position detecting unit for detecting a position deviation of the lens against the sled, a parameter generating unit for generating a tilt control parameter according to the position deviation, and a tilt control unit for controlling the lens according to the tilt control parameter so that the lens maintains horizontal with reference to the sled.

Abstract: A method and system for improving reliability in an optical storage system (100) is disclosed. A time shift measurement between two streams of information (150, 151) is performed during a writing operation of said optical storage system (100) to an optical storage medium (101), such as a CD, DVD or BluRay Disc (BD). Writing operation of the optical storage system is interrupted when the time shift measurement is greater than a predetermined level for detecting an irregularity in said optical storage system (100) during said writing operation, e.g. caused by a tangential shock, vibration, eccentricity or unbalance of the optical storage medium (101). Thus the irregularity, causing a faulty writing operation, the optical storage system (100) is quickly detected in order to prevent wasting a disc by interrupting recording as soon as a shock, vibration, etc. is detected by means of the measurement.

Abstract: A multiplexing optical system includes collimator lenses, a first condensing lens, a second condensing lens and an optical fiber. The collimator lenses collimate divergent laser beams that have been emitted from semiconductor lasers. The first condensing lens condenses laser beams transmitted through the collimator lenses in only one of a plane including the stripe width direction of the semiconductor lasers and a plane including a direction perpendicular to the stripe width direction. The second condensing lens condenses laser beams transmitted through the first condensing lens. The optical fiber is arranged in such a manner that the condensed laser beams enter the optical fiber. In the multiplexing optical system, an anamorphic lens is used as the second condensing lens, and the anamorphic lens condenses the laser beams in the two planes in cooperation with the first condensing lens.

Abstract: A detection signal S1 outputted from a light reception unit (11A) of detection elements (11) formed by four-division light reception element is added to a detection signal S4 outputted from a light reception unit (11D) so as to obtain an addition signal S14 and a phase difference signal P1 indicating the phase difference between the addition signal S14 and the detection signal S1. Furthermore, a phase difference signal P4 indicating the phase difference between the addition signal S14 and the detection signal S4 is obtained. The phase difference signal P4 is subtracted from the phase difference signal P1 so as to generate a tracking error signal TE1.

Abstract: The present invention is provides a method and apparatus for slip protection of DVD-RAM drive's seek control, comprising a slip end velocity controller, a re-seek controller, and a slip detector. Among them, the slip end velocity controller is used for providing a first control signal to direct a driver to control the slip end velocity of the optical head while seeking. The re-seek controller is capable of providing a second control signal to the seek controller for directing the seek controller to control the driver driving the optical head for re-seeking. The slip detector is used for receiving the TE signal sent from the preamplifier to determine if the optical head is slipping and to switch the input signal of the driver.

Abstract: In an information recording medium recording method, recording is interrupted, in recording on an information recording medium, when a predetermined interruption condition is met. A signal recorded in a recorded area is played back and a recording signal playback waveform signal is obtained. Error information indicating an error between a reference waveform signal derived by partial response equalization of a data string and the recording signal playback waveform signal is obtained. A recording condition is corrected on the basis of the error information. A recording/playback apparatus and information recording medium are also disclosed.

Abstract: An optical disk drive capable of detecting a surface deviation of a disk during a very short period includes an analog-to-digital converter (ADC) converting a focus error signal output from a pickup into digital data, and a central processing unit (CPU) writing an output of the ADC to a memory during one rotation of a motor according to a timing of a pulse signal output from a spindle motor. After that, the CPU reads data written to the memory and obtains a sine curve that minimizes the sum of squares of errors among data by a least square method. The CPU obtains a peak-to-peak value of the obtained sine curve and compares the peak-to-peak value to a predetermined threshold value, thereby determining the existence of the surface deviation of the disk.

Abstract: An optical pickup includes an objective lens for focusing a light beam onto an optical disc surface, a bobbin for supporting the objective lens, the bobbin having a first side face and a second side face on the opposite side of the bobbin with respect to the first side face, a first pair of suspension wires and a second pair of suspension wires, each wire having a first end and a second end, each of the first pair of suspension wires being attached to the first side face of the bobbin at the first end, and each of the second pair of suspension wires being attached-to the second side face of the bobbin at the first end, and a base to which each of the first and second pair of suspension wires is attached at the second end, for supporting the bobbin so that the bobbin can swing on the base. The first and second pair of suspension wires are plated in accordance with at least one different plating requirement between the first pair of suspension wires and the second pair of suspension wires.

Abstract: A method for calibrating a recording track offset of an optical storage device accessing an optical storage medium of a land and groove recording/reproduction type includes: setting at least one control parameter of a track offset control loop of the optical storage device to drive the track offset control loop to enter an first state; and recording data onto the optical storage medium with the track offset control loop being enabled to derive the latest value of the recording track offset, where the track offset control loop is utilized for controlling the recording track offset. The method further includes setting the control parameter to drive the track offset control loop to enter a second state, where a loop response of the track offset control loop in the first state is different from that in the second state.

Abstract: A digital video recorder writes data on a selected one of a first storage medium and a second storage medium. The recorder includes an abnormal state detector for detecting any abnormal event that possibly occurs while the recorder is writing the data on the first storage medium. If the abnormal state detector senses the abnormal event while the recorder is writing the data on the first storage medium, then the recorder stops writing the data on the first storage medium and starts writing the data, which should have been written on the first storage medium only, on the second storage medium instead.

Abstract: A tilt detection system includes an optical disk having a series of data recorded therein, the series of data having a pulse width smaller than the minimum pulse width of data recorded in an ordinary optical disk; a reproducing part reproducing a signal from the optical disk by emitting a light beam onto the optical disk; and a tilt detecting part detecting a tilt of the light beam with respect to the optical disk based on a reproduced RF signal provided by the reproducing part when the series of data having the smaller pulse width is reproduced.

Abstract: A method for controlling a tilt servo in an optical disc device is provided. The method includes (a) detecting a specific signal associated with a focus servo, and (b) generating a tilt servo control signal for an objective lens according to a variation amount of the specific signal.

Abstract: An optical disk apparatus includes a rotary driving unit rotating an optical disk which is flexible, an optical pickup irradiating light upon a recording surface of the optical disk on which writing/reading of information is performed, a stabilizing unit stabilizing vibration of the optical disk in a rotary axial direction by using pressure difference of air flow at least on a portion where writing/reading is performed, and being disposed on a side of the optical disk opposite to a side on which the recording surface is provided, and a control-adjustment unit analyzing a value of a tracking error signal of the optical disk obtained by scanning along a groove of the optical disk with use of the optical pickup, comparing the analyzed value of the tracking error signal of the optical disk and a value priorly obtained by scanning along a groove of a standard disk prepared beforehand, and adjusting a positional relation between the optical disk and the stabilizing member in a three dimensional space according to t

Abstract: A method and system for cross-talk cancellation in a three-spots push-pull tracking error signal in an optical disc system is disclosed. A tracking error signal (TES) is determined from a plurality of error signals (PPa, PPb, PPC). A noise signal (N) is determined from at least two of the plurality of error signals. The noise signal is filtered in a first filter (406).

Abstract: A method and apparatus for preventing a malfunction of a disc drive due to an operation error of a correction function for a minimum pit length by selectively performing the correction function based on an operative state of the disc drive. The method includes a first monitoring operation determining whether an operative state of the disc drive is stable when a disc is loaded into the disc drive, controlling a turning on of a correction function for a minimum pit length if the operative state of the disc drive is stable, and a second monitoring operation determining whether the operative state of the disc drive is stable after turning the correction function for the minimum pit length on and turning the correction function off if the operative state of the disc drive is determined to be unstable based on the second monitoring result.

Abstract: A method of reproducing an optical disk that that shortens the time between optical disk insertion and implementation of a standby mode enabling reproduction is provided that comprises a step of reading parameters stored in a nonvolatile memory, a step of deciding whether the optical disk can be properly reproduced using the read parameters, a step of, when it is found that the optical disk cannot be properly reproduced using the parameters, conducting a focusing search, reflection level detection, tracking error signal amplitude measurement and the like with respect to the optical disk, a step of specifying new parameters based on the result, and a step of storing the new parameters in the volatile memory.

Abstract: A noise canceling system includes a signal generator module that generates a set point signal based on a desired position signal and a position feedback signal, a summation module that generates an output control signal based on the set point signal and a correction signal, and a filter module that generates the correction signal based on a disturbance signal and that minimizes a correlation between the disturbance signal and an error signal. The error signal represents a difference between the desired position signal and the position feedback signal.

Abstract: According to one embodiment, an optical head device provides a signal processing circuit which sets a control amount to move an objective lens so that a distance between the objective lens and a given recording layer of the an optical disc coincides with a focal position, an optical path length correction mechanism which corrects an influence of an aberration component producing an error in the focal distance, a thickness difference detection circuit which finds an amount of correction to be made by the optical path length, and an aberration correction circuit which generates a correction signal to correct the influence of the aberration component producing the error in the focal distance detected by the thickness difference detection circuit, and supplies the correction signal to the optical path length correction mechanism.

Abstract: A Bemf detect circuit is configured for modeling Bemf error via calculation of time correlations associated with two or more different non-calibrated sense resistor gain values to derive a calibrated sense resistor gain value. A method is provided for calibrating a Bemf detector circuit by setting a sense resistor gain to a plurality of different gain values, observing Bemf sample values for each of the gain values, and deriving a calibrated gain value by non-iteratively modeling the relationship between the gain values and the associated Bemf sample values.

Abstract: An information recording apparatus according to one aspect of this invention comprises a detection unit configured to detect a manufacturing error unique to an information storage medium, a transmission unit configured to transmit the manufacturing error detected by the detection unit to an external apparatus, a reception unit configured to receive a recordable capacity which is calculated by the external apparatus on the basis of the manufacturing error transmitted from the transmission unit, a limitation unit configured to limit data to be supplied on the basis of the recordable capacity received by the reception unit, and a recording/aborting unit configured to record the recording data, supply of which is limited by the limitation unit, or to abort recording of the recording data.

Abstract: A light sensing area of a light sensing element is comprised of A1 region, A2 region, B1 region, B2 region and N region. A tilt detector carries out a tilt detection in accordance with a first difference signal, which is a difference signal between a signal obtained from the A1 region and a signal obtained from the B1 region, and a second difference signal, which is difference signal between a signal obtained from the A2 region and a signal obtained from the B2 region. Accordingly, an optical-disk tilt detecting signal having a little influence of defocusing can be obtained even at boundaries between recorded information tracks and non-recorded information tracks.

Abstract: An optical pickup records information on an optical recording medium and retrieves information from the optical recording medium by radiating a light beam on the optical recording medium. The optical pickup includes a light source which emits the light beam. The optical pickup also includes an object lens which directs the convergent light beam to a recording layer of the optical recording medium. The optical pickup further includes an aberration correction lens assembly located between the light source and the object lens. The aberration correction lens assembly includes at least one movable lens which is movable in an optical axis direction. The aberration correction lens assembly moves the movable lens to convert the light beam to a convergent light beam or a divergent light beam so as to correct spherical aberration.

Abstract: Astigmatism of a beam of first laser light is cancelled at a position separated from first optical element by a predetermined distance on an optical axis of the beam of first laser light by refracting to transmit the beam of the first laser light by being refracted by rotating by a predetermined angle around an axis orthogonal to the optical axis of the beam of the first laser light, refracting a beam of second laser light to coincide with the optical axis of the beam of the first laser light and rotating by a predetermined angle around a second axis orthogonal thereto.

Abstract: A method for detecting and controlling disc tilt in an optical disc mechanism comprising the steps of (A) measuring a 2-dimensional displacement of an optical lens of the optical disc mechanism, (B) extracting an absolute value of a disc tilt angle in the optical disc mechanism based upon the 2-dimensional displacement and (C) controlling deflection of a tilt moving coil according to the absolute value of the disc tilt angle.

Abstract: A focusing control method of an optical information storage media recording and/or reproduction apparatus controlling a focusing operation by moving an objective lens upwards or downwards in a direction towards or away from an optical information storage medium having a plurality of data layers includes receiving a focusing lead-in command signal to focus an optical beam on a target data layer, compensating for spherical aberration with respect to the target data layer, detecting a focus error signal based on an intensity of the optical beam reflected from the optical information storage medium and condensed by an optical detector, identifying the target data layer using an amplitude or a frequency of the focus error signal, and focusing the optical beam on the target data layer by moving the objective lens in an opposite direction from a direction in which the objective lens is initially moved.

Abstract: In an optical head device and an optical information recording/reproducing device using the optical head device, by driving a liquid crystal panel 4a, the liquid crystal panel 4a produces wave aberration for light on a going path and light on a returning path likewise. Accordingly, when the substrate-thickness deviation or tilt of the disc 7 is corrected, the wave aberration due to the substrate-thickness deviation or tilt of the disc 7 and the wave aberration produced by the liquid crystal panel 4a are canceled by each other for both of the light on the going path and the light on the returning path, so that no wave aberration remains for the light on the returning path and the phase distribution is not varied.

Abstract: A focus servo method used in an optical disc drive which is capable of accurately recording data to an optical disc just after starting recording of data to the optical disc is provided. The method includes a step of detecting a command signal for recording data to an optical disc; adding a predetermined amount of an offset component to a focus error signal for displacing an objective lens to a proper position for recording the data to the optical disc; starting recording the data to the optical disc after the offset component has been added; and decreasing the amount of the added offset component from the focus error signal after staring the recording of the data to the optical disc. The detecting step and the adding step are sequentially carried out in a region indicated by “B” in FIG. 1 and the step of starting recording of data and the step of decreasing the offset are sequentially carried out in a region indicated by “C” in FIG. 1.

Abstract: A tilt adjustment device for adjusting tilt of a left guide bar with respect to a right guide bar, and includes a holding seat and a cylindrical-shaped bushing disposed rotatably within the holding seat. The bushing defines a bar-retention hole to permit extension of the left guide bar therethrough, and has a turning portion defining a first axis and an insert portion that extends eccentrically from the turning portion and that defines a second axis parallel to the first axis. Rotation of the cylindrical-shaped bushing relative to the holding seat results in a radial movement of the turning portion, which, in turn, moves the first axis toward and away from the second axis of the insert portion.

Abstract: An optical disc apparatus is provided, which comprises a lens tilting section for tilting an objective lens to correct coma aberration occurring in a light beam spot focused on an information surface of an optical disc, a spherical aberration correcting section for correcting spherical aberration occurring in a light beam spot focused on the information surface, and a lens tilt-spherical aberration correction control section for controlling the spherical aberration correcting section to change an amount of spherical aberration correction performed by the spherical aberration correcting section depending on a tilt of the objective lens tilted by the lens tilting section.

Abstract: Provided is an optical disc device and a control method for the same that are capable of shortening processing time for spherical aberration correction amount adjustment. The optical disc device includes: a spherical aberration corrector that corrects spherical aberration of a light beam on an optical disc; and a tracking controller that performs tracking control based on a tracking error signal. In the spherical aberration correction amount adjustment by the spherical aberration corrector, the spherical aberration corrector is arranged so that: it holds a tracking error signal immediately before an spherical aberration correction amount is changed, and performs the tracking control based on the held tracking error signal while the spherical aberration corrector is changing the spherical aberration correction amount; or it moves a light beam scanning position on the optical disc to a predetermined track while the spherical aberration corrector is changing the spherical aberration correction amount.

Abstract: Even in the case where there is used technique such as “high NA”, “multi-layer recording”, etc., in order to carry out optimum correction of wave front aberration produced thereby with a simple technique, such an aberration correcting element to vary variable A and variable B(A?B) of phase distribution formula A(?r4)?B(?r2) as phase correction pattern by aberration correcting element is realized by using a liquid crystal element (30). The liquid crystal element (30) forms such an electrode pattern to generate phase distribution corresponding to spherical aberration at one transparent electrode (31A), and forms such an electrode pattern to generate defocus pattern at the other transparent electrode (31B). In addition, by controlling applied voltages with respect to these electrodes, it becomes possible to independently carry out variable control of the above-described variables A and B.

Abstract: The present invention provides a device and method for compensating signal in a light-scribe system. A light processing unit processes the reflection received by a light emitter to form a pulse wave. A microprocessor receives the pulse signal and detects the loss of pulse wave with a detector. A timer counts the interruption time of the pulse wave. A comparator compares the interruption time to a threshold. If the interruption time is greater than the threshold, a pulse generator produces a replacing pulse wave. A logical circuit receives the pulse wave and the replacing pulse wave, outputs the pulse wave from the light processing unit if there is loss of pulse wave, and outputs the replacing pulse wave if there is no pulse wave loss.

Abstract: A position sensor detects a position of an objective lens for irradiating light onto an optical disk. An output adjustment of the position sensor is used for correcting characteristics change due the change with the passage of time. The position of an objective lens and the output of a position sensor are measured at a reference time, the ratio at the neutral point is determined in advance, and when the device is used, the position of the objective lens and the output of the position sensor are measured. The output level at the neutral point during using the device is calculated from the measurement result and the ratio at the neutral point.

Abstract: A method for adjusting a tilt angle of a light beam emitted by an optical pickup unit of an optical disc drive, the method includes steps of adjusting the tilt angle of the light beam according to test parameters preinstalled in the optical disc drive; detecting focusing error signals, the focusing error signals being generated based on the light beam reflected from an optical disc; generating current parameters based on the focusing error signals; storing the current parameters; adjusting the tilt angle of the light beam according to the current parameters.

Abstract: A method for controlling write parameters in a data-write process includes steps of: emitting a laser beam to be focused on a disc to write data onto the disc; determining whether a check-point predetermined for the disc is detected; at occurrence of the check-point is detected, pausing the data-write process and starting to detect a quality of the data; judging whether a block error rate of the data exceeds a predetermined rate; calculating a write speed based on the block error rate; and adjusting the write parameters based on the quality and the write speed.

Abstract: A weighted defect estimating apparatus and a related method for determining a defect estimation value are disclosed. The weighted defect detecting apparatus includes: a defect detecting unit for generating a defect value when a defect in a predetermined region of an optical disc is detected; a weighting circuit, electrically connected to the defect detecting unit, to generate a weighted defect value according to the defect value and a weighting factor corresponding to a location of the defect on the optical disc; and a computing module, electrically connected to the weighting circuit, for computing the defect estimation value according to a plurality of weighted defect values corresponding to the predetermined region.

Abstract: An optical head with excellent optical characteristics even when using a light source that substantially has a wavelength broadening is provided. The optical head includes a light source, an objective lens for focusing a light beam emitted from the light source on an information recording medium and a photodetector for detecting the light beam reflected from the information recording medium, wherein defocusing correction means and spherical aberration correction means are provided in an optical path between the light source and the information recording medium. Since both the defocusing correction means and the spherical aberration correction means are provided, while defocusing of a focused spot on the information recording medium caused by a wavelength broadening of the light source and chromatic aberration of the optical system can be corrected, the spherical aberration of the optical system caused by wavelength difference between a design wavelength and an incident wavelength also can be corrected.

Abstract: An apparatus and a method for reducing a lead-in time of a disc, on which data is always recorded, and detecting exactly a tilt of the disc. The apparatus includes a pickup, and a system controller. Even if the disc is a blank disc which is devoid of user data, control data is recorded on the disc. The pickup can record data on the disc or reproduce data from the disc. If a seek command is received, the system controller detects the tilt of the disc once in each of a plurality of zones while the pickup is moving.

Abstract: A method is provided, which includes reading data from a data storage medium. Reading data from the medium causes the data to be erased. The method further includes determining a desired position to rewrite the data by computing a position error signal based on the data signal and compensating the position error signal for non-zero bias. The data is then rewritten non-synchronously. An apparatus is also provided, including a data storage medium with a data communication transducer configured to receive data from the medium. Data is erased after it is read. The data communication transducer is configured to rewrite the read data back onto the data storage medium in a non-synchronously. A non-zero bias compensator is provided to compensate data received by the data communication transducer to determine a desired position to rewrite the previously read data back onto the medium.

Abstract: A liquid crystal lens element having a lens function is provided, which is small sized without having moving part, and which can stably carry out correction of spherical aberration containing a power component corresponding to focal point change of incident light.

Abstract: [Problem to be Solved] It has been a problem that, with focusing servo control based on a focus error signal according to a conventional astigmatism method, due to a positional deviation of a received light beam on the light-receiving plane of a photodetector or an offset caused by asymmetry in the intensity distribution of reflected light, an error occurs in the focus error signal, whereby the focusing servo cannot correctly be performed.

Abstract: When an optical recording medium having a plurality of data layers is being read from and/or written to, the input beam experiences an aberration, inter alia in the top layers of the data layers. In order, nevertheless, to achieve a high data density, a device for correcting the spherical aberration is located in the beam path of the input beam. In the case of the use of an optical diode in which the input beam and the reflected beam have directions of polarization perpendicular to one another, such a device is expensive to implement and associated with a reduced optical efficiency. It is an object of the invention to propose an apparatus for reading from and/or writing to optical recording media, in the case of which a high optical efficiency and balancing of the spherical aberration are achieved with low outlay.

Abstract: An optical information recording/reproducing apparatus and are provided under a state where a focus servo is driven, a tracking error signal recorded on the recording medium or a sum signal of a photodetector is generated from a pencil of light guided onto the photodetector. Then, the signal amplitude of the tracking error signal or the sum signal of the photodetector is measured. Next, the relative tilt between the recording medium and the objective lens is roughly corrected until the signal amplitude reaches a threshold value determined in advance. After the rough correction, under a state where a tracking servo is driven on a predetermined track, tracking is performed on the predetermined track, detecting a tilt detection signal, and the relative tilt between the recording medium and the objective lens is finely corrected based on the tilt detection signal.