Abstract: By utilizing the fact that the observation object has a three-dimensional shape and the boundary surface can be regarded as a plane surface, phase or intensity distribution is applied into a luminous flux of reference light, thereby selectively attenuating the influence of the reflected light from the boundary surface so as to obtain a high-quality OCT image.

Abstract: An error correction encoding device 1 includes a sparse matrix computing unit 2 that computes exclusive OR of a submatrix, in a parity-check matrix, corresponding to an information bit sequence, and the information bit sequence on the basis of the position of 1 in the submatrix to calculate a vector, a fundamental matrix operator 3 that calculates a predetermined matrix by performing a predetermined fundamental matrix operation on a submatrix, in the parity-check matrix, corresponding to a parity bit sequence, and a matrix multiplier 4 that calculates the parity bit sequence by multiplying the predetermined matrix which the fundamental matrix operator 3 calculates, and the vector which the sparse matrix computing unit 2 calculates.

Abstract: An electromagnetic wave emission device includes a nonlinear crystal which receives exciting light Lp having two wavelength components ?1 and ?2, and outputs terahertz waves L1-L6, a total reflection layer which is in contact with the nonlinear crystal, and totally reflects the terahertz waves L2, L4, and L6 output from the nonlinear crystal, a substrate which mounts the total reflection layer, and top clads which are placed on an opposing surface of the nonlinear crystal, and transmit the terahertz waves L1-L6.

Abstract: Determining a parameter associated with whether a portion of a storage device is defective is disclosed. Determining comprises: obtaining known data associated with the portion; reading back from the portion to produce a read-back waveform; decoding the read-back waveform, including producing statistical information; and determining a parameter associated with whether the portion is defective based at least in part on the statistical information.

Abstract: Aspects of the disclosure provide a sync mark detector. The sync mark detector includes a first unit configured to decay over time a value indicating a length of a bit format, a second unit configured to compare the decayed value with a detected length of the bit format to determine a new length, and a third unit configured to detect a sync mark based on the detected length and the new length.

Abstract: There is provided a light source including a mode-lock laser unit that includes a semiconductor laser and an external resonator unit and emits a laser beam having a predetermined frequency, the semiconductor laser including a saturable absorber unit that applies a reverse bias voltage and a gain unit that applies a gain current, a semiconductor optical amplifier that performs amplification modulation on the laser beam emitted from the mode-lock laser unit, a laser clock generating unit that generates a laser clock synchronized with the laser beam based on a signal detected from the saturable absorber unit when the laser beam oscillates in the mode-lock laser unit, and a modulating unit that generates a driving current synchronized with the laser clock and applies the driving current to the semiconductor optical amplifier.

Abstract: The present invention is directed to system(s), method(s), and apparatus for accurate fast forward rate when performing trick play with variable distance between frames. In one embodiment, there is presented a circuit for providing a fast forward video sequence. The circuit comprises a system time clock for providing a time reference, said time reference incremented at a predetermined fast forward rate; a comparator for comparing the time reference with timing information associated with a picture; and a controller for determining whether to display the picture based at least in part on the comparison between the timing information and the time reference.

Abstract: In a system of detecting an interference light with a light not irradiated onto an optical disc to increase the S/N ratio, it is difficult to stably acquire a reproduced signal with a simple configuration. Since the recording density is not improved, an improvement in transfer rate is difficult. In an optical information recording/reproducing apparatus where two optical beams face each other and are focused at the same place of a recording medium to record a standing wave developed by interference of the two optical beams, a phase difference of the two optical beams is modulated in a multiple stage and recorded. During reproduction, an interference light of a reproduced light from the recording medium and another reproduction reference light is detected as a reproduced signal, and a phase servo control stabilizing the phase of interference during reproduction by using a low frequency component of the reproduced signal is conducted.

Abstract: A record carrier has a servo track indicating an information track intended for recording information blocks, which servo track has a variation of a physical parameter, referred to as wobble. The wobble is modulated for encoding record carrier information, such as addresses. The servo track is subdivided in non-modulated and parts modulated parts in which the frequency and/or phase of the variation deviates from the wobble frequency. The slope of the wobble is substantially continuous at transitions between the modulated and non-modulated parts by using wobbles starting at the maxima or minima of the wobble.

Abstract: Aspects of the disclosure provide a sync mark detector. The sync mark detector includes a first unit configured to decay over time a value indicating a length of a bit format, a second unit configured to compare the decayed value with a detected length of the bit format to determine a new length, and a third unit configured to detect a sync mark based on the detected length and the new length.

Abstract: An optical tape decoding system includes a decoder that may apply a matched pattern signal representing an address index to a track address signal including a multi-cycle wobble block representing the address index such that a signal is output having a peak corresponding to the multi-cycle wobble block. The decoder may also identify the address index based on an amplitude of the peak.

Abstract: In step S1, the address generator generates address information composed of a sync signal which is recorded on an optical disc, address data and an error correction code for the address data, pre-encodes and supplies it to a modulator. At the same time, a carrier signal generator generates a carrier signal which is to carry the address information, and supplies it to the modulator. In step S2, the modulator makes MSK modulation of the carrier signal supplied from the carrier signal generator on the basis of the pre-encoded address information supplied from the address generator, and supplies a resultant MSK modulation signal to a wobbling unit. In step S3, the wobbling unit forms, on the optical disc, a spiral groove wobbled adaptively to the MSK modulation signal supplied from the modulator. In this optical disc, a given address can be accessed quickly and accurately.

Abstract: Provided is an optical disk recording device including: a recording pulse information generation unit that generates, from a recording signal, recording pulse information corresponding to a power level of laser light; a recording code generation unit that generates a recording code by encoding the recording pulse information; and a decoded code generation unit that decodes the recording code. The recording code generation unit generates the recording code based on a cyclic cede representing each transmission of the power level by using a Gray code. The decoded code generation unit decodes the recording code by using a recording code corresponding to a power level at a predetermined timing and a recording code corresponding to a power level immediately prior to the power level at the predetermined timing.

Abstract: According to one embodiment, an information storage medium in which layer 0 and layer 1 are arranged from a read surface, a system lead-in area, data lead-in area, data area, and middle area are arranged from an inner circumference of the layer 0, and a system lead-out area, data lead-out area, data area, and middle area are arranged from an inner circumference of the layer 1. A guard track zone is arranged on a side of the data area in the data lead-out area, and a reference code zone, R physical format information zone, recording management zone, and drive test zone are arranged in the data lead-in area of the layer 0 and padding of the guard track zone of the data lead-out area is performed after padding of the drive test zone of data lead-in area and recording of the recording management zone.

Abstract: According to an embodiment, a storage medium includes a transparent resin substrate having a concentric or spiral groove and a recording film formed on the groove on the transparent resin substrate, a recording mark being formed by irradiation of a laser beam, wherein a reproduction durability count in a case where reproduction is continuously carried out by a laser beam is 1,000,000 or more.

Abstract: A data recovery device including an analog to digital converter (ADC), a filtering-equalizing unit, a zero crossing detector, a data phase locked loop, a data mapping unit and an estimation unit is provided. The ADC converts a radio frequency signal to a plurality of sampling data points. The sampling data points are converted to a plurality of retiming data points and a clock signal by the filtering-equalizing unit, the zero crossing detector and the data phase locked loop. The data mapping unit selects a plurality of maximum data points and minimum data points from the returning data points, and determines whether to map the maximum data points and the minimum data points to other levels for partially reconstructing the retiming data points. The estimation unit recovers the reconstructed retiming data points to a modulation signal.

Abstract: A recording apparatus for recording information on an optical recording medium includes a mode-locked laser unit that includes a semiconductor laser emitting a laser beam for recording the information on the optical recording medium, and an external resonator, an optical modulation unit that amplifies and modulates the laser beam emitted from the mode-locked laser unit, a recording signal generation unit that generates a recording signal based on a reference signal from a drive of the optical recording medium, and a modulation unit that generates a modulation signal for driving the optical modulation unit by latching the recording signal using a laser clock generated by an oscillation pulse of the laser beam emitted from the mode-locked laser unit.

Abstract: In a method of modulating/demodulating a signal, a transmission signal is generated from an input data signal including data information by combining a plurality of input shift clock signals, which are modulated based on input clock signal during an interval period of the input clock signal, during 2 interval periods of the input clock signal. An output clock signal is detected and an output clock signal is generated from the transmission signal by combining a plurality of output shift clock signals, demodulated based on the output clock signal during an interval period of the output clock, during 2 interval periods of the output clock signal, to restore the data information.

Abstract: A data recovery device including a filter, a tilt detection unit, a tilt cancellation unit and a data conversion unit is provided. The filter filters a radio-frequency data stream to generate an original data stream. The tilt detection unit synthesizes a tangential push-pull data stream by employing a first to a fourth data streams, and generates a tilt direction signal according to symmetry of a curve composed by the tangential push-pull data stream. The tilt cancellation unit detects a plurality of rising areas and falling areas of the original data stream, and reconstructs a plurality of data points corresponding to the rising areas or falling areas in the original data stream so as to generate a tilt repair data stream. The data conversion unit recovers the tilt repair data stream to a modulation signal.

Abstract: The present invention achieves an optical recording and reproducing apparatus focusing two opposed beams of light at a same place in an optical recording medium to record a standing wave generated by interference of the two beams of light. In the apparatus, phase information is recorded in the optical recording medium by a phase modulating means for modulating phase of one of the two beams of light. The reproduction reference light generated from a light source is allowed to interfere with reproduced light generated by projecting one of the two beams of light onto the optical recording medium to generate three or more beams of interfering light having different interference phases are simultaneously generated. The three or more beams of interfering light are then detected, and the phase modulated by the phase modulating means is demodulated from an output of the detector.

Abstract: In a medium of the phase change type, a power ratio and modulation degree for use in recording are determined from a recommended pulse width value in the recommended write strategy parameters recorded in the optical disk, the recommended power ratio value, the recommended recording power value, and the characteristics of the optical recording device, and recording is carried out on the optical disk according to the power ratio value and modulation degree value thus determined. Optimal recording can be carried out even on an optical disk for which the optimal write strategy information has not been determined in advance, without the need to store write strategy information suitable for each and every optical disk.

Abstract: An optical disc apparatus includes an optical pickup including: a light source; an objective lens for converging a light flux emitted from the light source and forming an optical spot on an information recording plane of an optical disc; and an optical modulation unit divided into a plurality of areas for modulating an area containing a main beam of the light flux to change a shape of the optical spot, wherein data is reproduced by converting a reproduction signal read from the optical disc with the optical pickup into an NRZI signal of a predetermined modulation rule by a PRML method. An optical spot shape, laser power setting and PRML setting are changed with each optical disc and each drive operation state.

Abstract: A method of modulating and demodulating a signal includes modulating data information included in an input data signal provided from an external source and clock information included in an input clock signal provided from the external source into a transmission signal, using (n+1) delay clock signals generated based on the input clock signal, where n is a natural number. The transmission signal is demodulated into an output clock signal including restored clock information and an output data signal including restored data information, using (m+1) delay clock signals generated based on the clock information, where m is a natural number less than n.

Abstract: In one embodiment the present invention includes a circuit comprising a switch and a switch driver. The switch is configured to provide synchronous rectification switching of a back-EMF voltage. The synchronous rectification switching produces a source voltage. The switch driver is configured to receive the back-EMF voltage and the source voltage. The switch driver provides a control signal to a control terminal of the switch. The control signal has a frequency. The frequency is used to control an amount of the synchronous rectification switching. Accordingly, the frequency reduces a dissipated power associated with the synchronous rectification switching.

Abstract: Circuits, architectures, systems, methods, software, and algorithms for detecting a modulation transition (e.g., a change from a written portion containing RF-modulated data to an unwritten portion containing only a wobble signal modulation) on an optical storage medium. The method generally includes steps of focusing a first spot of light onto an optical storage medium, wherein the first spot is substantially centered on a first track of the optical storage medium, focusing a satellite spot of light onto an optical storage medium, wherein the satellite spot at least partially overlaps a track adjacent to the first track, generating a satellite signal from light reflected from the optical storage medium from the satellite spot, and detecting the modulation transition by detecting a change in a level of the satellite signal.

Abstract: An integrated circuit is provided in an optical disc apparatus for drawing a visible image on an optical disc including a discoloration layer which is discolored by heat or light by irradiating the optical disc with laser light. The integrated circuit includes a tracking direction displacement section configured to execute, when the visible image is drawn, oscillation control to oscillate a position irradiated with the laser light in a radial direction of the optical disc, and a laser modulation section configured to change, when the visible image is drawn, an intensity of the laser light so that the higher a displacement rate of the position irradiated with the laser light in the radiation direction is, the higher the intensity of the laser light becomes.

Abstract: A digital recording apparatus for recording 1-bit digital audio data of a first sampling frequency on a recording medium in accordance with the recording format of multi-bit PCM data of a second sampling frequency includes a storage section to which input 1-bit digital audio data of the first sampling frequency is written; an encoder configured to read, from the storage section, the 1-bit digital audio data at a clock synchronized with the second sampling frequency and configured to convert the 1-bit digital audio data in such a manner that bits of the 1-bit digital audio data are arrayed in a 1-bit data area provided in the multi-bit PCM data that is in accord with the recording format; and a recorder configured to record data output from the encoder on the recording medium in accordance with the recording format.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit is discussed that includes a summation circuit, a data detector circuit, an error feedback circuit, and an error calculation circuit. The summation circuit subtracts a low frequency offset feedback from an input signal to yield a processing output. The data detector circuit applies a data detection algorithm to a derivative of the processing output and provides an ideal output. The error feedback circuit includes a conditional subtraction circuit that conditionally subtracts an interim low frequency offset correction signal from a delayed version of the derivative of the processing output to yield an interim factor. The error calculation circuit generates an interim low frequency offset correction signal based at least in part on the interim factor and a derivative of the ideal output.

Abstract: A method and apparatus for stably encoding/decoding data, and a method and apparatus for recording/reproducing data are disclosed. The method inserts decoding information into a data section including several predetermined-bit data, determines encoding values of the data according to a transition state of the data and a value of corresponding data, and generates the decoding information and the determined encoding values in units of the data section.

Abstract: An optical storage medium can be provided by which illegal usage of the optical storage medium involving an infringement on the copyright can be prevented effectively without impairment of the functions for reproducing physical format information and optical storage medium manufacturing information. The optical storage medium includes a main information region in which encrypted data information is recorded as a pit row that is capable of being read out by means of light and a control data region. In the control data region, key information for decoding the encryption of the data information, the physical format information and the optical storage medium manufacturing information are recorded by wobbling a groove.

Abstract: An optical recording/reproducing system 1 reads a recorded signal written to a recording track of a recording medium 3 by light. The light is modulated by a drive signal on which a frequency signal is superimposed. The light is scanned along the recording track at a predetermined scan velocity. The optical recording/reproducing system 1 includes a computer 13 and an LD driver 17 that control, based on the scan velocity, a superimposed magnitude of the frequency signal on the drive signal.

Abstract: A method for storing data on a storage medium is provided. The method includes receiving a modulated bitstream, wherein the modulated bitstream comprises a plurality of bits comprising a bitstate of 1 and 0. The method also includes secondary modulating each of the pluality of bits comprising the bitstate of 1 to output a plurality of secondary modulated bits. The method further includes forming a plurality of marks in the storage medium, the marks indicative of each of the plurality of secondary modulated bits and the plurality of bits comprising the bitstate of 0 in the modulated bitstream.

Abstract: An optical information recording reproducing apparatus precisely decides at least the time width of a recording pulse sequence so as to obtain a preferable signal quality by controlling a recording power and a pulse time width during a high-speed write. The apparatus includes: modulation instrument for generating a test pattern containing at least a first recording mark length; recording pulse sequence conversion instrument for converting the test pattern into a recording pulse sequence containing test recording pulses having different time widths corresponding to at least the first recording mark length; beam irradiation instrument; reproduced signal processing instrument for holding as a first signal index characteristic, the relation between a first signal index acquired according to the reproduced signal obtained from a predetermined area and the recording power; and recording condition calculation instrument for obtaining a desired time width of a recording pulse of the first recording mark length.

Abstract: A decoding apparatus includes a burst cutting area (BCA) signal interval measuring device which measures a signal interval of a BCA area and which outputs BCA signal interval information, a T converter which obtains T information from the BCA signal interval information, a sequencer which detects a space area based on a first threshold value and which outputs an output enable signal based on the T information and a detecting result, wherein the output enable signal shows that a signal is obtained from a data area of the BCA area, and the space area is a non-signal area of the BCA area, and a channel data converter which converts the T information into channel data based on the output enable signal from the sequencer.

Abstract: An information recording method, including detecting a synchronous signal and first address information from a recording medium, on which the synchronous signal and the first address information have been preformatted in a wobbled groove track, which is divided into a first unit with a predetermined length on the wobbled groove track. The method further includes constructing the track into second units, the second unit having a length different from the first unit with the predetermined length, and generating second address information indicating the constructed second units.

Abstract: A method of recording data onto an optical storage medium includes: before starting recording data onto the optical storage medium from an expected link point on the optical storage medium, setting a current recording condition corresponding to the expected link point according to at least one previous recording condition corresponding to the expected link point; and controlling an operation of recording the data onto the optical storage medium according to the current recording condition.

Abstract: The disclosure is a data modulation/encryption method used in a holographic storage system. The data modulation method includes steps of: receiving an original data sequence; arraying the original data sequence to a first matrix with n×n dimensions; multiplying the first matrix by a sparse matrix to generate a second matrix with n×n dimensions; executing a modulating and mapping procedure for generating a third matrix with (n+1)×n or n×(n+1) dimensions, wherein the third matrix is composed of a modulation part and an extra part; and, storing the third matrix; wherein the sparse matrix is a binary matrix, a total number of elements in each row of the sparse matrix is odd, all rows of the sparse matrix have a same even number of bit 1, all columns of the sparse matrix have a same even number of bit 1, and the sparse matrix has an inverse matrix.

Abstract: An apparatus and a method for generating ATIP data is provided. The apparatus generates ATIP data from a wobble signal of a re-writable compact disc. The apparatus includes a frequency demodulator for demodulating the wobble signal to generate an original ATIP data signal; an ATIP clock generating circuit for generating an ATIP clock signal based on the wobble signal; and a data generating circuit, coupled to the frequency demodulator and the ATIP clock generating circuit, for generating the ATIP data based on the number of measurement periods for which the original ATIP data signal is at a first logic level during one period of the ATIP clock signal. This apparatus uses this number and the bi-phase rule to precisely generate ATIP data.

Abstract: An optical recording/reproducing system 1 reads, based on a predetermined reproduction clock, information associated with a recording track of a recording medium by irradiating frequency light. The frequency light is scanned at a predetermined scan velocity. The optical recording/reproducing system includes a computer 13, a DSP 49, and a LD driver that modulate light by a drive signal on which a frequency signal is superimposed to thereby output the frequency light, and synchronizes a frequency of the frequency signal with a frequency of the reproduction clock according to the scan velocity.

Abstract: A digital data demodulator which can reduce a loss of decodable digital data, and increase capability of reproducing digital data inputted through a transmission line even when an error occurs in the transmission line. In the digital data demodulator, a specific pattern detector (113) detects a specific pattern to be included in a modulation code, from a bit string inputted through a transmission line (104). A modulation code identifying unit (117) generates a demodulation data strobe signal (119) according to a phase of the modulation code including the specific pattern. An error corrector (121) samples demodulation data (109) in response to the demodulation data strobe signal (119) and reproduces the data to the original digital data.

Abstract: In a system of detecting an interference light with a light not irradiated onto an optical disc to increase the S/N ratio, it is difficult to stably acquire a reproduced signal with a simple configuration. Since the recording density is not improved, an improvement in transfer rate is difficult. In an optical information recording/reproducing apparatus where two optical beams face each other and are focused at the same place of a recording medium to record a standing wave developed by interference of the two optical beams, a phase difference of the two optical beams is modulated in a multiple stage and recorded. During reproduction, an interference light of a reproduced light from the recording medium and another reproduction reference light is detected as a reproduced signal, and a phase servo control stabilizing the phase of interference during reproduction by using a low frequency component of the reproduced signal is conducted.

Abstract: An address format for appropriately controlling the recording linear density and the number of information recording layers is provided in order to increase the recording capacity of an information recording medium such as an optical disc or the like in a range in which a necessary S/N ratio can be guaranteed. An optical disc includes an information recording layer having a concentric or spiral track, and has a format for describing a track address, which is pre-recorded on the track or is to be added to data that is to be recorded on the information recording layer. The format includes layer information regarding the information recording layer and address information regarding the track address.

Abstract: A big pattern for a run-in area which allows data reproduction to be performed stably even when the recording density of an optical disc is increased is provided. An optical disc according to the present invention includes tracks, each of which divided into a plurality of recording blocks. Each of the plurality of blocks includes a run-in area and a data area. In the run-in area, a prescribed run-in bit pattern is recordable; and in the data area, bit patterns having a plurality of bit lengths obtained by modulating data as a recording target in accordance with a prescribed modulation rule are recordable. In this optical disc, at least one of spatial frequencies corresponding to the bit patterns having the plurality of bit lengths is higher than a cutoff frequency. The run-in bit pattern recordable in the run-in area includes the bit patterns having the plurality of bit lengths, from which the bit pattern corresponding to the frequency higher than the OTF cutoff frequency has been excluded.

Abstract: An aligned write signal generator with alignment calibration utilizes an alignment unit to align a plurality of write signal. The aligned write signal generator includes a write signal generator for receiving an EFM signal and converting the EFM signal into a plurality of write signals according to a write strategy waveform generating rule, an alignment unit for receiving the plurality of write signals, aligning the write signals and outputting phase adjusted write signals, and a phase calibration unit for receiving the phase adjusted write signals, detecting phase error between the phase adjusted write signals, and outputting phase control signals. The alignment unit further receives the phase control signals to adjust the delay time of each write signal.

Abstract: Provided is an optical disk apparatus which optimizes a frequency of a high frequency superimposing operation upon reproduction so that good reproduction performance is realized in a wide irradiation power range of a laser power. The optical disk apparatus includes: a semiconductor laser device; an optical disk discrimination circuit for performing laser discrimination; a driver device including a drive circuit for supplying direct drive current to the semiconductor laser device and a high frequency superimposing circuit for superimposing high frequency current on the drive current; and a high frequency superimposing variable circuit for changing a frequency of the high frequency current in which when information is reproduced, the high frequency superimposing variable circuit sets the frequency of the high frequency current for reproducing a multi-layer disk to be higher than the frequency of the high frequency current for reproducing a single-layer disk.

Abstract: A pre-treating circuit for accessing the disc and a method thereof, which are especially used for treating the signal waveform that violates the encoding rule of the disc information, are provided. The present invention can modulate the signal waveform that violates the encoding rule, so that the waveform is not changed during at least 3 continuous periods of the clock signal. The present invention also replaces any wrong 16-bit data which violate the encoding rule, with approximated 16-bit data before they are decoded, or receives approximated 8-bit data which correspond to the incorrect 16-bit data, by directly referring to a table. Therefore, the subsequent decoding module can acquire more data for continuous processing, so as to improve the data reading reliability and to prevent the “picky disc” or “disc error reading” problem from happening.

Abstract: A record carrier (1) has a servo track (4) indicating an information track (9) intended for recording information blocks. The servo track (4) has a periodic variation of a physical parameter at a predetermined frequency, usually called wobble. The servo track has modulated parts for encoding position information according to a predetermined type of modulation. The record carrier includes a management area in which the servo track includes permanent data. The permanent data is encoded using a different type of modulation, but using the variations of the same physical parameter. Direct digital modulation (41) is proposed for the different type of modulation.

Abstract: A record carrier (1) has a servo track (4) indicating an information track (9) intended for recording information blocks. The servo track (4) has a periodic variation of a physical parameter at a predetermined frequency, usually called wobble. The servo track has modulated parts for encoding position information according to a predetermined type of modulation. The record carrier includes a management area in which the servo track includes permanent data. The permanent data is encoded using a different type of modulation, but using the variations of the same physical parameter. Direct digital modulation (41) is proposed for the different type of modulation.

Abstract: A record carrier has substantially parallel tracks having first variations of a first physical parameter and second variations of a second physical parameter of the track. The first variations represent information recorded on the record carrier, this information being recoverable by a controllable type of data processing. A modulation pattern of the second variations represents a code for controlling the type of data processing. In respect of a code track that includes the modulation pattern, the modulation pattern in the left neighboring track is aligned to the modulation pattern in the right neighboring track. Thereby crosstalk due to the second variations is decreased, and at least two tracks have the same modulation pattern. The playback device has a demodulator (50) and a control unit (56) for retrieving the code from at least two tracks.

Abstract: An information system according to the invention comprises a record carrier and a playback apparatus. The record carrier has information marks along a track thereof and exhibits first variations caused by existence and nonexistence of the information marks along the track. The first variations represent an information signal recorded on said record carrier. The record carrier further exhibits second variations caused by variations associated with the information marks. The phase of the second variations is coupled to the phase of the first variations.