KR20080099455A - Apparatus for recoding optical information, apparatus for reproducing optical information, method for recoding optical information and method for reproducing optical information - Google Patents

Abstract

An optical information recording apparatus, an optical information readout device, an optical data recording method and an optical information reproducing apparatus are provided to reduce a bit error rate(BER) of an optical information storage medium by detecting a tracking error with track servo beam and correcting the tracking error with a refraction part refracting reference beam. An optical information recording apparatus includes a light source(110); a reference beam optical system(150) projecting reference beam for optical data recording which is separated from the light emitted from the light source to an optical information storage medium in which a track is formed by an interference pattern of reference beam for and servo beam for track recording; a sensor sensing the track servo beam generated as the reference beam for optical data recording is projected to the track; and a signal beam optical system(130) which loads signal beam separated from the light emitted from the light source with optical information and projects the signal beam to intersect with the reference beam for optical data recording in the sensed track.

Description

Optical information recording apparatus, optical information reproducing apparatus, optical information recording method and optical information reproducing method {Apparatus for recoding optical information, apparatus for reproducing optical information, method for recoding optical information and method for reproducing optical information}

1 is a block diagram showing an optical information recording and reproducing apparatus according to an embodiment of the present invention.

2 is a block diagram showing an optical information recording and reproducing apparatus at the time of optical information reproduction.

3 is a block diagram illustrating a correction unit of a tracking error according to an embodiment of the present invention.

4 is a block diagram illustrating an operating state of a compensator, according to an exemplary embodiment.

5 is a block diagram illustrating an operating state of a correction unit according to another exemplary embodiment.

6 is a flowchart illustrating an optical information recording method according to an embodiment of the present invention.

7 is a flowchart illustrating a method of reproducing optical information according to an embodiment of the present invention.

8 is a graph illustrating a tracking error due to vibration.

9 is a graph illustrating the tracking error corrected by the correction unit.

<Description of Symbols for Main Parts of Drawings>

110: light source

120: optical separation unit

130: signal light optical system

140: servo light optical system

150: reference light optical system

160: correction unit

170: optical information storage medium

The present invention relates to an optical information recording apparatus, an optical information reproducing apparatus, an optical information recording method, and an optical information reproducing method, and more particularly, an optical information recording apparatus, an optical information reproducing apparatus, and an optical information recording capable of correcting a tracking error. It relates to a method and a method for reproducing optical information.

Optical data processing apparatuses include Digital Versatile Disc (DVD), HD-DVD, Blu-ray Disc (BD), near field optical information processing apparatus, and holographic optical information processing apparatus.

The holographic optical information processing apparatus separates light having coherency generated by a laser light source into a signal beam and a reference beam carrying optical information and simultaneously enters both light into the optical information storage medium. In this case, a spatial interference pattern of two lights is recorded, and when only the reference light is incident on the optical information storage medium, the reference light is diffracted in the interference pattern to generate a reproduction light having optical information.

Unlike conventional methods such as DVD, which stores brightness information one by one for each specific coordinate to store optical information, the holographic optical information processing apparatus uses Fourier transform method to convert the entire information of the plane. It is a mass storage technology that uses a page-oriented memory method that records at one point.

In addition, the holographic optical information processing apparatus uses a multiplexing technique, which is a technique of overlapping recording and reproducing an interference pattern at the same point in order to increase the recording density of data. Multiplexing techniques include angle multiplexing, phase-coded multiplexing, wavelength multiplexing, and shift multiplexing.

Here, the angle multiplexing is to change the incident angle of the reference light incident on the optical information storage medium, the phase code multiplexing is to spatially modulate the phase, and the wavelength multiplexing is recorded on the optical information storage medium according to the wavelength change using a wavelength tunable laser. The interference pattern is changed, and shift multiplexing is recording while moving the optical information storage medium.

In the holographic optical information processing apparatus which records optical information at high density using a multiplexing technique or the like, servo control for accurately recording optical information and accurately reading the recorded optical information is very important.

Optical information storage media are usually manufactured in the form of discs, such as CD-ROMs. When the disk-type optical information storage medium is rotated at high speed, the reference light may not be properly incident on the track on which the optical information is recorded due to the rocking of the optical information storage medium and the swinging of the rotating motor. There is a need for a way to correct this.

An object of the present invention is to provide an optical information recording apparatus, an optical information reproducing apparatus, an optical information recording method, and an optical information reproducing method capable of correcting a tracking error.

An optical information recording apparatus according to an embodiment of the present invention for achieving this object is a light source, a reference light for recording the optical information separated from the light emitted from the light source tracks consisting of the reference pattern for the track recording and the interference pattern of the servo light A reference light optical system incident on the formed optical information storage medium, a detector for detecting a track servo light generated by the reference light for recording the optical information entering the track, and loading the optical information into a signal light separated from the light emitted from the light source. And a signal light optical system for injecting the signal light to intersect the reference light for recording the optical information in the track sensed by the sensing unit.

The optical information recording apparatus may further include a correction unit that corrects an error in which the reference light for recording the optical information deviates from the track.

The correction unit is a refraction unit for refracting the reference light for recording the optical information, the control unit for determining the rotation angle of the refraction unit by determining the error deviation of the reference light from the track with the track servo light detected by the detection unit The actuator may include an actuator for rotating the refraction unit.

The refractive portion may be a flat plate having a specific thickness and a specific refractive index.

The actuator may rotate the refraction unit about at least one of an X axis and a Y axis.

The detector may be at least one of a two segment detector, a four segment detector, and a position sensitive detector.

An optical information recording apparatus according to another embodiment of the present invention includes a light source, a signal light optical system which loads optical information into a signal light separated from the light emitted from the light source and enters the optical information storage medium, and is separated from the light emitted from the light source. A reference light optical system for injecting reference light to the signal information in the optical information storage medium, a servo light optical system for injecting servo light separated from the light emitted from the light source to intersect the reference light in the optical information storage medium, the reference light and the servo light And a detecting unit for detecting a track servo light reproduced from a track formed of an interference pattern of the optical signal, and a correcting unit correcting an error in which the reference light deviates from the track by refracting the reference light.

The corrector may include a refraction unit for refracting the reference light, a control unit for determining an angle of rotation of the refraction unit by determining an error that the reference light deviates from the track by the track servo light detected by the detection unit, and the refraction unit according to the determination of the control unit. It may include an actuator to rotate.

The refractive portion may be a flat plate having a specific thickness and a specific refractive index.

The actuator may rotate the refraction unit about at least one of an X axis and a Y axis.

An optical information reproducing apparatus according to another embodiment of the present invention provides a light source and a reference light for reproducing optical information emitted by the light source to an optical information storage medium having a track formed of an interference pattern of a reference light and a servo light for track recording. A detection unit for detecting track servo light reproduced from the track by a reference light optical system, a reference light for reproducing the optical information, and a detection unit for detecting optical information reproduction light reproduced from an interference pattern recorded along the track detected by the detection unit Include.

The optical information reproducing apparatus may further include a correction unit configured to correct an error in which the reference light for reproducing the optical information deviates from the interference pattern.

The correction unit is a refraction unit for refracting the reference light for reproducing the optical information, the control unit for determining the rotation angle of the refraction unit by obtaining an error that the reference light for reproducing the optical information from the track with the track servo light detected by the detection unit And an actuator for rotating the refraction unit according to the determination of the controller.

The refracting part may be a balance plate that refracts reference light for reproducing the optical information with a specific thickness and a specific refractive index.

The optical information recording method according to another embodiment of the present invention comprises the step of injecting the reference light for recording the optical information to the optical information storage medium is formed a track consisting of the reference pattern for the track recording and the interference pattern of the servo light, which is reproduced from the track Detecting a track servo light, obtaining an error in which the reference light for recording the optical information deviates from the track, correcting the error by refracting the reference light for the optical information recording, and the optical information storage medium And recording the interference pattern by incident the reference light for recording the signal light and the optical information.

The optical information recording method may further include recording a track by injecting the reference light and the servo light into the optical information storage medium before the reference light for the optical information recording into the optical information storage medium. Can be.

The step of correcting the error may be refracting the reference light for recording the optical information so that the traveling direction of the reference light before refracting and the traveling direction of the reference light after refracting are maintained in the same direction.

The optical information reproducing method according to another embodiment of the present invention comprises injecting reference light for reproducing optical information into an optical information storage medium on which a track comprising a reference light for track recording and an interference pattern of servo light is formed. Detecting a track servo light, obtaining an error in which the reference light for reproducing the optical information deviates from the track, correcting the error by refracting the reference light for reproducing the optical information, and recording along the track And injecting reference light for reproducing the optical information into the interference pattern, and detecting the reproducing light information reproduced from the interference pattern.

The correcting of the error may include refracting the reference light for reproducing the optical information such that the traveling direction of the reference light before refracting and the traveling direction of the reference light after refracting are maintained in the same direction.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

1 is a block diagram showing an optical information recording and reproducing apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the optical information recording and reproducing apparatus includes a light source 110, an optical separation unit 120, a signal light optical system 130, a servo light optical system 140, a reference light optical system 150, a correction unit 160, and a detection unit. 161 and the detector 180.

The light source 110 may use a laser oscillator capable of emitting a laser having good coherency. He-Ne laser, Ar laser, semiconductor laser, etc. can be used as a laser oscillator. The light emitted from the light source 110 may be a blue beam having a wavelength between 450 nm and 500 nm or a green beam having a wavelength between 500 nm and 570 nm. This is not a limitation, and light having a wavelength of 500 nm or less or a wavelength of 600 nm or more may be applied.

The light splitter 120 includes a first light splitter 121 and a second light splitter 122. The first light splitter 121 may be a non-polarizer beam splitter. The first light splitter 121 includes a semi-transmitting film that partially reflects and partially transmits the light emitted from the light source 110. The transmittance of the semi-transmitting film can be controlled by varying the proportion of constituents. The second light splitter 122 may be a polarizer beam splitter. The second light splitter 122 transmits the P-polarized light of the light transmitted through the first light splitter 121 and reflects the S-polarized light. The first light reflected by the first light splitter 121 is used as a signal beam S. The second light reflected by the second light splitter 122 is used as a servo beam (T). The light transmitted through the second light splitter 122 is used as a reference beam (R).

The signal optical system 130 includes a first shutter 131, a beam expander 132, a first reflecting mirror 133, a first polarizing plate 134, a spatial light modulator 135, and a Fourier transform lens. lens, 136). The first shutter 131 is opened at the time of recording the optical information to pass the signal light S, and closed at the time of reproducing the optical information to block the signal light S. FIG. The beam expander 132 extends the signal light S to an appropriate size for loading optical information. The first reflection mirror 133 reflects the signal light S to the optical information storage medium 170. The first polarizer 134 may be a half wave plate (HWP). The first polarizing plate 134 transmits only the S-polarized light of the signal light S. The signal light S transmitted through the first polarizing plate 134 is incident to the spatial light modulator SLM 135.

The spatial light modulator 135 is composed of a thin film transistor liquid crystal (TFT LC), a super twisted nematic liquid crystal (STN LC), a ferroelectric liquid crystal (LC), a polymer dispersed liquid crystal (PDLC) of a passive matrix, It may be provided with a transmissive spatial light modulator such as a plasma driven liquid crystal (PALC). The spatial light modulator 135 loads the optical information into the signal light (S). The Fourier transform lens 136 performs Fourier transform on the signal light S loaded with the optical information and enters the optical information storage medium 170.

The servo light optical system 140 includes a second shutter 141, a second reflecting mirror 142, and an aperture 143. The second shutter 141 is opened when the track is recorded on the optical information storage medium 170, passes through the servo light T, and is closed when the optical information is reproduced to block the servo light T. The second reflection mirror 142 reflects the servo light T onto the optical information storage medium 170. The diaphragm 143 reduces the diameter of the servo light T.

The reference light optical system 150 includes a third reflecting mirror 151, a second polarizing plate 152, and a lens for reference light 153. The third reflection mirror 151 reflects the reference light R to the optical information storage medium 170. The third reflection mirror 151 may be a galvano mirror that vibrates or rotates at a high speed of several micrometers. The second polarizer 152 may be a half wave plate (HWP). The second polarizing plate 152 changes the reference light R of P polarized light into S polarized light. The reference light lens 153 reduces the diameter of the reference light R incident on the optical information storage medium 170.

The optical information storage medium 170 is made of a material in which interference patterns of the signal light S, the servo light T, and the reference light R can be recorded. As the optical information storage medium 170, a photopolymer, which is a photocurable polymer in which an interference pattern is recorded, may be used as a monomer turns into a polymer. In addition, the optical information storage medium 170 may be a silver salt photosensitive plate, dichromatic gelatin (DCG), thermoplastic, photochromic material, and the like.

The detector 180 is positioned on the optical path of the signal light S transmitted through the optical information storage medium 170. The detector 180 may employ an image sensing device having a pixel array such as a charge-coupled device (CCD) and a complementary metal-oxide semiconductor (CMOS).

The detector 161 is positioned on the optical path of the servo light T passing through the optical information storage medium 170. The detector 161 may detect a change in the amount of light incident on the light as a two split detector or a four split detector. In addition, the detector 161 may be a detector that detects a position of incident light, such as a position sensitive detector (PSD). As the sensing unit 161, a PN photodiode, an avalanche photodiode, or the like, which is an optical sensor that converts light energy into electrical energy, may be used.

The corrector 160 includes a controller 162, an actuator 163, and a refraction unit 164. The controller 162 calculates the degree to which the reference light R deviates from the track by the change in the amount of light detected by the detector 161. The control unit 162 determines the rotation angle of the refracting unit 164 to correct the degree of deviation of the reference light R from the track. The actuator 163 rotates the refracting portion 164 by the determined rotation angle.

The refraction unit 164 may be optical glass having a specific thickness and a specific refractive index. The refraction unit 164 may be a flat plate that transmits the reference light R that is incident vertically as it is. The refracting unit 164 may be rotated at a specific angle by the actuator 163, and the reference light R may be incident to the refracting unit 164 at a specific incident angle. The reference light R incident on the refraction unit 164 at a specific incident angle is refracted and incident on the optical information storage medium 170. At this time, the optical path of the reference light R is moved by the refraction to enter the optical information storage medium 170.

2 is a block diagram showing an optical information recording and reproducing apparatus at the time of optical information reproduction.

Referring to FIG. 2, when reproducing optical information, the first shutter 131 and the second shutter 141 are closed to block the signal light S and the servo light T. The reference light R is incident on the interference pattern recorded on the optical information storage medium 170 to generate reproduction light. The interference pattern may be an interference pattern recorded by the interference between the signal light S and the reference light R, and a track recorded by the interference between the servo light T and the reference light R. The reference light R is diffracted by the interference pattern recorded as the interference between the signal light S and the reference light R to generate the optical information reproduction light Sr. The optical information reproduction light Sr is incident to the detector 180. The reference light R is diffracted by the track recorded by the interference of the servo light T and the reference light R to generate the track servo light Tr. The track servo light Tr is incident to the detector 161.

The optical information recording and reproducing apparatus has been described above, but the optical information recording and reproducing apparatus except for the detection unit 180 can be configured. The optical information storage medium 170 may have a track including an interference pattern of the servo light T and the reference light R in advance. The optical information recording apparatus for recording optical information on the optical information storage medium 170 having a track may be configured to exclude the servo optical system 140 and the detector 180. In addition, the optical information reproducing apparatus may be configured by the light source 110, the reference light optical system 150, the detecting unit 180, and the detecting unit 161, which are parts necessary for reproducing the optical information.

3 is a block diagram illustrating a correction unit of a tracking error according to an embodiment of the present invention. The reference light R is out of the track.

Referring to FIG. 3, the refraction portion 164 may be a balance plate having a specific thickness d and a specific refractive index n. One side of the refracting portion 164 is connected to the actuator 163 and the connecting portion 165.

When the reference light R enters the refracting portion 164 vertically, the reference light R is not refracted and passes through the refracting portion 164 as it is. The reference light R passing through the refraction unit 164 enters the track of the optical information storage medium 170. The track servo light Tr is generated by the interference pattern of the track. The track servo light Tr enters the sensing unit 161.

The reference light R may not enter the track correctly and may deviate from the track. The error x 'in which the reference light R deviates from the track is called a tracking error. The amount of light of the track servo light Tr incident on the sensing unit 161 in the tracking error state is not uniformly detected. For example, when the sensing unit 161 is a two-segment detector having an A sensing area and a B sensing area, the track servo regeneration in which the amount of light of the track servo reproducing light Tr entering the A sensing area is incident to the B sensing area. The amount of light Tr may be greater than the amount of light. The controller 162 can obtain a difference between the electric energy generated in the A sensing region and the electric energy generated in the B sensing region, and calculates an error x 'in which the reference light R deviates from the track.

4 is a block diagram illustrating an operating state of a compensator, according to an exemplary embodiment. This indicates a state in which the reference light R corrects the error x 'deviated from the track.

Referring to FIG. 4, the control unit 162 determines the rotation angle α of the refracting unit 164 according to the error x ′ in which the reference light R deviates from the track. When the refracting portion 164 is rotated by the rotation angle α, the incident angle at which the reference light R is incident on the refracting portion 164 becomes α. The reference light R incident on the refracting portion 164 at the incident angle α travels with the refracting angle of β within the refracting portion 164. Generally α> β. The reference light R traveling in the refraction portion 164 with a refraction angle of β is refracted at an angle of α when exiting the refraction portion 164. Therefore, the reference light R transmitted through the refraction unit 164 proceeds in the same direction as the reference light R incident to the refraction unit 164 but moves only in position.

The optical path of the reference light R refracted by the refraction unit 164 is determined by a distance x that is moved according to the rotation angle α of the refraction unit 164. The relationship between the moving distance x of the optical path and the rotation angle α of the refraction unit 164 may be expressed by Equation 1 below.

으로 나타낼 수 있다. Where x is the moving distance of the optical path, d is the thickness of the refracting portion 164, n is the refractive index of the refracting portion 164, α is the rotation angle of the refracting portion 164 (incidence angle of the reference light R), β Denotes the angle of refraction of the reference light R incident into the refraction portion 164. β is determined according to the refractive index n of the refraction unit 164 and the rotation angle of the refraction unit 164,

It can be represented as

The refractive index n of the refraction portion 164 is determined according to the type of the refraction portion 164. For example, when the refraction portion 164 is the borosilicate crown glass BK7, the refractive index is determined by a constant of 1.516. The thickness d of the refraction portion 164 may be determined in advance in consideration of the interval between tracks and the degree of tracking error.

The movement distance x of the optical path increases as the rotation angle α of the refraction unit 164 increases. For example, assuming that n = 1.5 and d = 500 μm of the refraction unit 164, the moving distance x of the optical path of the reference light R is the rotation angle α of the refraction unit 164. As shown in Table 1.

Rotation angle (α °) Travel distance (x ㎛) Rotation angle (α °) Travel distance (x ㎛) 0 5 10 15 20 25 30 0 14.6 29.4 44.8 61.0 78.2 96.9 0 -5 -10 -15 -20 -25 -30 0 -14.6 -29.4 -44.8 -61.0 -78.2 -96.9

Here, the negative sign means that the optical path of the reference light R moves in the opposite direction when the refracting portion 164 is rotated in the opposite direction. By rotating the refracting portion 164 by 30 degrees, the optical path of the reference light R may be moved by about 100 μm. This is merely an example and is not a limitation. The refractive index n and the thickness d of the refraction portion 164 may be variously selected, and accordingly, the rotation angle α and the moving distance x of the optical path of the refraction portion 164 may be variously changed. Can be. In addition, although the refractive unit 164 has been described as a flat plate, the refractive unit 164 may have a convex lens shape, a concave lens shape, or the like, and may have a layered structure of a plurality of materials having different refractive indices. There will be.

5 is a block diagram illustrating an operating state of a correction unit according to another exemplary embodiment.

Referring to FIG. 5, the actuator 163 may rotate the refracting unit 164 about an X axis center and a Y axis center. That is, in FIG. 4, the refraction unit 164 is rotated around the actuator 163 as the central axis, but as shown, the refraction unit 164 may be rotated around the connection unit 165.

The actuator 163 is assumed to be the X axis and the connecting portion 165 is assumed to be the Y axis. When the refraction unit 164 is rotated around the Y axis, the movement distance x of the optical path of the reference light R may be represented as described with reference to FIG. 4.

However, the movement direction of the optical path when the refraction unit 164 is rotated around the Y axis is the direction perpendicular to the movement direction of the optical path when the refraction unit 164 is rotated around the X axis. . When the refraction unit 164 is rotated around the X axis, the optical path moves along the Y axis, and when the refraction unit 164 is rotated around the Y axis, the optical path moves along the X axis. As such, the refraction unit 164 may be rotated with respect to any one of the X axis and the Y axis.

The refraction unit 164 may be rotated around both the X axis and the Y axis. When the refracting portion 164 is rotated around the X and Y axes, the optical path of the reference light R moves on the XY plane. When the refraction unit 164 is rotated around the X and Y axes, the reference light R can correct an error that deviates from the spot of the interference pattern recorded on the optical information storage medium 170. In this case, the quadrature detector or a position sensitive detector (PSD) may be adopted as the detector 161 to obtain an error in which the reference light R deviates from the spot of the interference pattern.

The correction unit 190 that moves the optical path by using the refraction unit 164 is not only a holographic data storage (HDS) optical information processing device, but also an optical measuring device such as a 3D scanner, a micro processing device using a laser, and light. It may be implemented by various modifications or changes to the device and parts of the device using the light, such as the image forming apparatus and the inspection device of the printed circuit board.

6 is a flowchart illustrating an optical information recording method according to an embodiment of the present invention.

Referring to FIG. 6, first, optical paths of the signal light S, the servo light T, and the reference light R will be described. The light emitted from the light source 110 is split into the signal light S and the temporary light in the first light splitter 121. The temporary light is split into the servo light T and the reference light R in the second light splitter 122.

The signal light S passes through the first shutter 131 and extends in the beam expander 132. The extended signal light S is reflected by the first reflection mirror 133 and enters the spatial light modulator 135 through the first polarizing plate 134. In this case, while the signal light S passes through the first polarizing plate 134, only the S polarization component is incident on the spatial light modulator 135. The signal light S loaded with the optical information from the spatial light modulator 135 is incident on the optical information storage medium 170 through the Fourier transform lens 136. The servo light T is reflected by the second reflection mirror 142 through the second shutter 141 as the S polarization component. The servo light T reflected by the second reflection mirror 142 passes through the aperture 143 and enters the optical information storage medium 170. The reference light R is reflected by the third reflecting mirror 151 and converted into the S polarization component while passing through the second polarizing plate 152. The reference light R of the S-polarized component passes through the lens 153 for reference light and enters the optical information storage medium 170.

The reference light R forms an interference pattern with the signal light S and the servo light T in the optical information storage medium 170. The interference pattern between the reference light R and the signal light S includes optical information. The interference pattern between the reference light R and the servo light T becomes a track for correcting the tracking error.

When recording the optical information, the track may be first recorded on the optical information storage medium 170, and the interference pattern of the reference light R and the signal light S may be recorded along the track. The signal light S is blocked by the first shutter 131, and the servo light T and the reference light R are incident on the optical information storage medium 170 to record the track (S110). The reference light R at this time may be referred to as the reference light R for track recording. The track serves as a reference for the interference pattern of the reference light R and the signal light S to be recorded in the optical information storage medium 170. The track may be recorded in advance in the optical information storage medium 170. If the track is recorded in advance in the optical information storage medium 170, the recording process of the track (S110) can be omitted.

After the track is formed on the optical information storage medium 170, the reference light R is incident on the track of the optical information storage medium 170 (S120). The detector 161 detects the track servo light Tr reproduced from the track by the reference light R (S130). The reference light R at this time may be referred to as the reference light R for recording optical information.

The control unit 162 obtains an error from the track servo light Tr detected by the sensing unit 161, in which the reference light R for recording the optical information deviates from the track (S140). The controller 162 determines the rotation angle of the refraction unit 164 according to this error. The actuator 163 rotates the refracting portion 164 according to the determined rotation angle. The optical path of the reference light R for recording the optical information refracted by the rotated refraction unit 164 is moved in parallel to correct an error in which the reference light R for the optical information recording deviates from the track (S150). At this time, the advancing direction of the reference light R before refracting by the refracting unit 164 and the advancing direction of the reference light R after refracting by the refracting unit 164 are maintained in the same direction, and the reference light for optical information recording ( The position of the light path of R) is moved.

Signal light S and reference light R for recording the optical information are incident on the optical information storage medium 170 while the reference light R for the optical information recording is offset from the track, and the interference includes the optical information. The pattern is recorded (S160).

On the other hand, when recording the optical information, the interference pattern of the signal light (S) and the reference light (R) and the tracks of the servo light (T) and the reference light (R) can be recorded at the same time. The first shutter 131 and the second shutter 141 are opened to enter the signal light S, the servo light T, and the reference light R into the optical information storage medium 170. An interference pattern of the signal light S and the reference light R and a track of the servo light T and the reference light R are recorded in the optical information storage medium 170.

7 is a flowchart illustrating a method of reproducing optical information according to an embodiment of the present invention.

Referring to FIG. 7, the reference light R emitted from the light source 110 passes through the refraction unit 164 and enters the track of the optical information storage medium 170 (S210).

When the reference light R is incident on the track of the optical information storage medium 170, the track servo light Tr is generated. The generated track servo light Tr is incident to the detector 161. The detector 161 detects the track servo light Tr (S220). The reference light R at this time may be referred to as reference light R for reproducing optical information.

The detector 161 generates an electrical signal by measuring the amount of light of the track servo regenerated light Tr. The controller 162 converts an electrical signal into a voltage signal and amplifies it. The controller 162 removes high frequency noise from the voltage signal, and calculates an error x ′ in which the reference light R for reproducing optical information from the voltage signal deviates from the track (S230).

The control unit 162 determines the rotation angle α of the refraction unit 164 according to the error x 'of the reference light R for reproducing the optical information from the track. The actuator 163 rotates the refracting portion 164 by the determined rotation angle α. The reference light R for reproducing the optical information transmitted through the rotated refraction unit 164 is refracted to move the optical path by x, and the error x 'that the reference light R for the optical information reproducing from the track is corrected is corrected. It becomes (S240). At this time, the advancing direction of the reference light R before refracting by the refracting unit 164 and the advancing direction of the reference light R after refracting by the refracting unit 164 are maintained in the same direction, and the reference light for reproducing optical information ( The position of the light path of R) is moved.

In operation S250, the reference light R for reproducing the optical information is incident on the optical information storage medium 170 in the state in which the error x ′ of the deviation from the track is corrected (S250). The optical information reproducing light Sr is generated from the interference pattern recorded on the optical information storage medium 170 and is incident to the detector 180. The detector 180 detects the optical information reproduction light Sr (S260).

The process of correcting the tracking error may be repeatedly performed along with the process of detecting the optical information reproduction light Sr. By repeatedly correcting the tracking error due to the shaking of the device together with the detection of the optical information reproduction Sr, it is possible to increase the detection efficiency of the optical information reproduction light Sr.

8 is a graph illustrating a tracking error caused by the shaking of the device. 9 is a graph illustrating the tracking error corrected by the correction unit. 8 illustrates a case in which the tracking error is not corrected, and FIG. 9 illustrates a case in which the tracking error is corrected by the correction unit 160.

8 and 9, when the tracking error is not corrected, it can be seen that the error x 'that the reference light R deviates from the track appears. It can be seen that the position error signal (PES) measured by the sensing unit 161 varies between -100 μm and +100 μm. This may be a tracking error due to vibration of the device or vibration from the outside. Due to this tracking error, the shape of the data page reproduced by the detector 180 may be unevenly detected. This causes a decrease in the optical information reproduction efficiency.

When the tracking error is corrected by the correction unit 160, it can be seen that the PES measured by the detection unit 161 appears to be nearly zero. Tracking errors due to vibration of the device or vibration from the outside can be corrected to increase the optical information reproduction efficiency.

As mentioned above, preferred embodiments of the present invention have been described in detail, but those skilled in the art to which the present invention pertains should understand the present invention without departing from the spirit and scope of the present invention as defined in the appended claims. It will be appreciated that various modifications or changes can be made. Therefore, changes in the future embodiments of the present invention will not be able to escape the technology of the present invention.

As described above, according to the present invention, a track servo light reproduced at the optical information storage medium with the interference pattern of the servo light and the reference light can be used to detect a tracking error in which the reference light deviates from the track by the track servo light reproduced at the time of optical information recording and reproduction of optical information. have. By correcting the detected tracking error by using a refraction unit that refracts the reference light, the bit error rate BER due to the fluctuation of the optical information storage medium or the fluctuation of the device can be reduced.

Claims (19)

Light source; A reference light optical system for inputting a reference light for recording optical information separated from the light emitted from the light source into an optical information storage medium having a track formed of an interference pattern of reference light and servo light for track recording; A detector for detecting a track servo light generated by the reference light for recording the optical information into the track; And And a signal light optical system which loads the optical information into the signal light separated from the light emitted from the light source, and injects the signal light to intersect the reference light for recording the optical information in the track detected by the sensing unit. Device. The optical information recording apparatus according to claim 1, further comprising a correction unit for correcting an error in which the reference light for recording the optical information deviates from the track. 3. The apparatus of claim 2, wherein the correction unit comprises: a refraction unit for refracting a reference light for recording the optical information; A controller configured to determine a rotation angle of the refraction unit by obtaining an error in which the reference light deviates from the track by the track servo light detected by the detection unit; And And an actuator for rotating the refraction unit according to the determination of the controller. 4. The optical information recording apparatus according to claim 3, wherein the refraction portion is a flat plate having a specific thickness and a specific refractive index. 4. The optical information recording apparatus according to claim 3, wherein the actuator rotates the refraction unit about at least one of an X axis and a Y axis as a central axis. The optical information recording apparatus of claim 1, wherein the sensing unit is at least one of a two-segment detector, a four-segment detector, and a position sensitive detector. Light source; A signal light optical system for loading optical information into signal light separated from the light emitted from the light source and incident the optical information onto an optical information storage medium; A reference light optical system for incident a reference light separated from the light emitted from the light source to cross the signal light in the optical information storage medium; A servo light optical system for incident the servo light separated from the light emitted from the light source to cross the reference light in the optical information storage medium; A detector for detecting a track servo light reproduced from a track comprising an interference pattern of the reference light and the servo light; And And a correction unit for refracting the reference light to correct an error in which the reference light deviates from the track. The apparatus of claim 7, wherein the correcting unit comprises: a refracting unit refracting the reference light; A controller configured to determine a rotation angle of the refraction unit by obtaining an error in which the reference light deviates from the track by the track servo light detected by the detection unit; And And an actuator for rotating the refraction unit according to the determination of the controller. 9. The optical information recording apparatus according to claim 8, wherein the refraction portion is a flat plate having a specific thickness and a specific refractive index. 9. The optical information recording apparatus according to claim 8, wherein the actuator rotates the refraction unit about at least one of an X axis and a Y axis as a central axis. Light source; A reference light optical system for inputting a reference light for reproducing optical information emitted by the light source into an optical information storage medium having a track formed of an interference pattern of a reference light for servo recording and a servo light; A detector for detecting a track servo light reproduced from the track by reference light for reproducing the optical information; And And a detection unit for detecting the optical information reproduction light reproduced from the interference pattern recorded along the track detected by the detection unit. 12. The optical information reproducing apparatus according to claim 11, further comprising a correction unit for correcting an error in which the reference light for reproducing the optical information is out of the interference pattern. 13. The apparatus of claim 12, wherein the correction unit comprises: a refraction unit that refracts reference light for reproducing the optical information; A control unit for determining a rotation angle of the refraction unit by obtaining an error in which the reference light for reproducing the optical information is separated from the track by the track servo light detected by the detection unit; And And an actuator for rotating the refraction unit according to the determination of the controller. The optical information reproducing apparatus according to claim 13, wherein the refraction unit is a balance plate that refracts the reference light for reproducing the optical information with a specific thickness and a specific refractive index. Injecting the reference light for optical information recording into an optical information storage medium having a track formed of a reference light for track recording and an interference pattern of servo light; Detecting track servo light reproduced from said track; Obtaining an error in which the reference light for recording the optical information deviates from the track in the detection result; Refracting the error by refracting the reference light for recording the optical information; And And recording an interference pattern by injecting a signal light and a reference light for recording the optical information into the optical information storage medium. 16. The method of claim 15, further comprising: recording a track by injecting the reference light and the servo light into the optical information storage medium before the reference light for the optical information recording into the optical information storage medium. Optical information recording method, characterized in that. The optical information of claim 15, wherein the correcting of the error comprises refracting the reference light for recording the optical information such that the traveling direction of the reference light before refracting and the traveling direction of the reference light after refracting are maintained in the same direction. How to record. Injecting the reference light for optical information reproduction into an optical information storage medium having a track formed of a reference light for track recording and an interference pattern of servo light; Detecting track servo light reproduced from said track; Obtaining an error in which the reference light for reproducing the optical information deviates from the track in the detection result; Correcting the error by refracting the reference light for reproducing the optical information; Injecting reference light for reproducing the optical information with the interference pattern recorded along the track; And Detecting optical information reproduction light reproduced from the interference pattern. The optical information of claim 18, wherein the correcting of the error comprises refracting the reference light for reproducing the optical information such that the traveling direction of the reference light before refracting and the traveling direction of the reference light after refracting are maintained in the same direction. How to play.

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