KR100767934B1 - Tracking error detection method and optical information reproducing apparatus using same - Google Patents

Abstract

A tracking error detection method for detecting a tracking error for a current track is provided. The tracking error detection method irradiates reference light over the current track, a first peripheral track adjacent to the current track, and a second peripheral track. The first ambient light corresponding to the first peripheral track side and the second ambient light corresponding to the second peripheral track side are detected by being separated from the reproduction light reproduced by the reference light. Next, a tracking error is detected using the light intensity of the first ambient light and the light intensity of the second ambient light.

Description

Tracking error detecting method and optical information reproducing apparatus using the same}

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

2 is an exemplary diagram illustrating a region where a track and a reference light are incident on an optical information recording medium.

3 is a schematic diagram showing the reproduction light detected through the photo detector when there is no tracking error.

4 is a schematic diagram illustrating reproduction light detected through a photo detector when there is a tracking error.

5 is a diagram illustrating a function of light intensity when the tracking error of FIG. 4 occurs.

6A to 6C are diagrams showing the light intensity detected by each photodiode of the photodetector.

7A to 7C are graphs showing tracking errors.

8A to 8C are graphs showing each tracking error when the efficiency is different.

9A to 9C are graphs showing each tracking error when the efficiency is different.

10 is a schematic diagram showing an optical information recording and reproducing apparatus according to another embodiment of the present invention.

** Explanation of symbols in main part of drawing **

110: optical system

150: ambient light separator

160: optical information detector

170: light detector

180: signal processing unit

The present invention relates to a tracking error detecting method and an optical information reproducing apparatus using the same, and more particularly, to a tracking error detecting method using a peripheral track and an optical information reproducing apparatus using the same.

Recently, the information and communication industry and the multimedia industry, which are rapidly growing, require a large storage device for contents of high-capacity images and videos as well as existing text data. As a result, optical information processing apparatuses using holography, which have high storage capacity and can access information at high speed, have attracted attention.

Optical information processing apparatus using holography is a page-oriented memory in principle of recording and reproducing image information. This can speed up the data rate. In addition, the storage density can be dramatically improved through a multiplexing technique in which image information is superimposed on the same place on the recording medium.

A general optical information processing apparatus using holography uses an optical information recording medium in the form of a disk. As the optical pickup moves along the track of the optical information recording medium, data is recorded in the recording area included in each track or data is reproduced from the recording area.

In order to increase the reliability of the optical information processing apparatus using holography, it is necessary to minimize the bit error rate (BER), which is an error rate during data reproduction. In order to minimize BER, a reference beam must accurately follow the center of the track on which data is recorded.

An example of a tracking error detection method has been disclosed by H. Horimai in US Patent Application Publication No. 2005/0030875 entitled "Optical information recording apparatus and optical information reproducing apparatus." According to Horimai, a light source for reproducing data and a light source for obtaining a servo signal are used separately. The light reflected on the pit previously recorded on the optical information recording medium is detected by a photo diode or the like to obtain a tracking error signal.

Another example of a tracking error detection method has been disclosed by Zhou et al. In US Pat. No. 5,982,513 entitled "Method and system to align holographic images." According to Enzo et al., When recording a data image on an optical information recording medium, the servo image which is configured separately from the data is also recorded. The servo image is detected from the data image reproduced by the reference light with a photodiode or the like to obtain a tracking error signal.

There is a need for a method for accurately detecting tracking errors. The tracking error signal obtained through the amount of light detected in the light reproduced or reflected from the optical information recording medium may vary in sensitivity depending on diffraction efficiency or ambient influence in the recording area. In addition, if the tracking error signal is not symmetrical about the origin (if there is no track error), complex computational and calibration procedures are required to determine the tracking error.

Therefore, tracking error detection with low sensitivity and symmetry is required.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a reliable tracking error detection method and an optical information reproducing apparatus using the same.

Another object of the present invention is to provide a tracking error detection method using reproduction light reproduced from surrounding tracks and an optical information reproducing apparatus using the same.

According to an aspect of the present invention, there is provided a tracking error detection method for detecting a tracking error for a current track. The tracking error detection method irradiates reference light over the current track, a first peripheral track adjacent to the current track, and a second peripheral track. The first ambient light corresponding to the first peripheral track side and the second ambient light corresponding to the second peripheral track side are detected by being separated from the reproduction light reproduced by the reference light. Next, a tracking error is detected using the light intensity of the first ambient light and the light intensity of the second ambient light.

According to another aspect of the present invention, a tracking error detection method is provided. The tracking error detection method detects a first ambient light by a first track of an optical information recording medium and a second ambient light by a second track of the optical information recording medium, and detects an optical intensity error of the first ambient light and the first ambient light. The value obtained by dividing the sum of the light intensities of the two ambient lights by the sum of the light intensities of the first ambient light and the light intensities of the second ambient light is detected as a tracking error.

According to still another aspect of the present invention, there is provided an optical information reproducing apparatus for reproducing optical information from an optical information recording medium including a plurality of tracks. The optical information reproducing apparatus includes: a current track including a recording area in which data to be reproduced is recorded; an optical system for irradiating reference light over a first peripheral track and a second peripheral track adjacent to the current track; Dividing the optical information into a main reproduction light reproduced in the recording area, a first ambient light by the first peripheral track and a second ambient light by the second peripheral track, and the optical information from the main reproduction light. A light information detector for detecting, a first photo detector for detecting the first ambient light, a second photo detector for detecting the second ambient light, and received light intensity values detected by the first and second photo detectors, The sum of the light intensity error of the first ambient light and the light intensity error of the second ambient light divided by the sum of the light intensity of the first ambient light and the light intensity of the second ambient light is detected as a tracking error. Includes a signal processor.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like numbers refer to like elements throughout.

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

Referring to FIG. 1, the optical information reproducing apparatus 100 includes an optical system 110, an ambient light separator 150, an optical information detector 160, an optical detector 170, and a signal processor 180.

The optical system 110 includes a light source 112 and a multiplexer 114. The reference light generated by the light source 110 is incident on the optical information recording medium 200 via the multiplexer 114. The multiplexer 114 adjusts the angle at which the reference light is incident on the optical information recording medium 200 to implement angle multiplexing. The multiplexer 114 may be a rotating mirror such as a galvano mirror.

The optical information recording medium 200 includes a recording area in which optical information is recorded (or to be recorded). When the reference light is incident on the recording area, the reference light is diffracted on the interference pattern formed in the recording area to generate reproduction light. The optical information recording medium 200 includes a plurality of tracks arranged in concentric circles in the form of a disc. Each track includes a plurality of recording areas.

2 is an exemplary diagram illustrating a region where a track and a reference light are incident on an optical information recording medium.

Referring to FIG. 2, an L2 track, an L track, a current track, an R track, and an R2 track are sequentially disposed from the center of the optical information recording medium 200 to the outside.

The current track refers to a track including a recording area Rc for reproducing the current data, and is a track to follow the correct position by detecting the current tracking error. The current track may correspond to any of the tracks of the optical information recording medium 200.

Surrounding tracks are located to the left and right of the current track. L tracks (first peripheral tracks) and L2 tracks are sequentially arranged on the left side of the current track, and R tracks (second peripheral tracks) and R2 tracks are sequentially arranged on the right side. Here, the left side is one side of the current track, and the right side is the other side of the current track, and is not necessarily limited to the illustrated direction.

In each track, respective recording areas Rc, R _L , R _L2 , R _R and R _R2 are formed. 2 shows one recording area Rc, R _L , R _L2 , R _R , and R _R2 , but a plurality of recording areas Rc, R _L , R _L2 , R _R , and R _{R2 are} provided along each track. Is formed. In the recording areas Rc, R _L , R _L2 , R _R , and R _R2 , interference patterns by reference light and information light are recorded. When the reference light is irradiated to the recording areas Rc, R _L , R _L2 , R _R , and R _R2 , the reference light is diffracted by the interference pattern to generate the same reproduction light as the information light used for recording.

In order to reproduce the original data, the reference light only needs to be irradiated to the recording area Rc of the current track. However, in the present invention, the reference light is irradiated to include not only the current track but also its surrounding track. I.e., reference light is the current is incident over a track and its adjacent tracks, which are the L track, R the track, the recording area of the L track as well as the recording region (Rc) of the current track (R _L), the recording region (R _R) of the R track Investigate all at once.

However, the reference light does not necessarily need to be irradiated including the recording area R _L of the L track or the recording area R _R of the R track, but is incident on the surrounding tracks wider than the recording area Rc of the current track. . In one embodiment, the reference light may be irradiated over part of the L track or part of the R track. In another embodiment, the reference light can be incident over an L2 track outside of the L track or an R2 track outside of the R track.

Since the reference light is irradiated wider than the recording area Rc of the current track, the reproduction light reproduced by the reference light includes not only the reproduction light by the recording area Rc of the current track, but also the reproduction light by the surrounding tracks. In other words, when the reference light is incident on the L track and the R track, the reproduction light is generated by the reproduction light by the recording area Rc of the current track, the recording area R _L of the L track, or the recording area R _R of the R track. Includes reproduction light. In the following description, the reproduction light in the recording area Rc of the current track among the reproduction light is called the main reproduction light, and the reproduction light in the recording area of the peripheral track except the main reproduction light is referred to as ambient light.

Referring back to FIG. 1, the reproduced light reproduced by the reference light is incident to the polarized light separator 124 after passing through the first lens 122. Polarized light separator 124 passes P-polarized light and reflects S-polarized light. Here, P polarization and S polarization mean polarization states perpendicular to each other, and do not mean absolute polarization states.

When the regenerated light has P polarization, it is converted to circular polarization while passing through a polarization light separator 124 and a wave wave plate 126. Subsequently, the regenerated light is collected by the second lens 128 and proceeds to the ambient light separator 150.

An aperture 155 is formed in the ambient light separator 150 to pass only the main reproduction light of the reproduction track by the recording area Rc of the current track. The ambient light separator 150 is a kind of Nyquist filter.

The main reproduction light passing through the opening 155 is detected by the optical information detector 160 via the third lens 165. The optical information detector 160 is configured of a pixel array such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) to detect optical information included in main reproduction light. Accordingly, the optical information detector 160 detects a data page for the recording area Rc of the current track.

On the other hand, the reflection surface 156 reflecting the reproduction light is formed on the surface except the opening 155 among the surface where the reproduction light is incident to the ambient light separator 150. In the absence of a tracking error, only the main reproduction light passes through the opening 155 and the ambient light is reflected by the reflecting surface 156. The regenerated light that does not pass through the opening 155 is reflected by the reflecting surface 156 and is incident to the second lens 128 again.

The reflected regenerated light is converted from circularly polarized light to S-polarized light while passing through the second lens 128 and passing through the wave plate 126. Accordingly, the S-polarized regenerated light is reflected by the polarized light separator 124 and travels toward the fourth lens 129. The regenerated light passing through the fourth lens 129 is incident to the photo detector 170.

The photo detector 170 detects the light intensity of the reproduction light. The photo detector 170 may be configured as a photo diode or a photo diode array. The signal processor 180 receives the light intensity of the reproduction light obtained through the photo detector 170 and detects a tracking error.

3 is a schematic diagram showing the reproduction light detected through the photo detector when there is no tracking error.

Referring to FIG. 3, the regenerated light passing through the fourth lens 129 is detected by the photo detector 170 in the form of a spot. Here, the S _L2 spot is a spot caused by the reproduction light for the recording area R _L2 of the L2 track, the S _L spot is a spot caused by the reproduction light for the recording area R _L of the L track, and the Sc spot is currently The spot by the reproduction light to the recording area Rc of the track, the S _R spot is the spot by the reproduction light to the recording area R _R of the R track, and the S _R2 spot is the recording area (R _R2) of the R2 track. Is the spot caused by the regenerated light.

The photo detector 170 is separated into a first photo detector 172 and a second photo detector 172 so that the first photo detector 172 detects the S _L spot and the second photo detector 174 is S _R. Spot is detected.

The first photodetector 172 includes two photodiodes A and B divided into two. The first photodetector 172 is divided into two in the rotational direction (or track direction) of the optical information recording medium 200. The position error of the S _L spot can be known through the light intensity error due to the light intensity P _A detected by the photodiode A and the light intensity P _B detected by the photodiode B. That is, when there is no tracking error, if the light intensity error is P _A -P _B = 0, the position error of the S _L spot can be known through the value and the sign of the light intensity error P _A -P _B.

The second photo detector 174 includes two photodiodes C and D divided into two. By detecting the light intensity P _C detected by the photodiode C and the light intensity P _D detected by the photodiode D, the position error of the S _R spot can be known.

The photo detector 170 includes first and second photo detectors 172 and 174, but the photo detector 170 is not limited thereto and may be configured as one photo detector. In addition, the photo detector 170 may be configured through not only a photodiode but also other photodetectors for detecting light intensity.

Using the light intensity of the reproduced light detected by the photo detector 170, the signal processor 180 calculates a tracking error TE as shown in Equation 1 below.

In the present invention, the tracking error is obtained through the difference in the light intensity by the ambient light. The ambient light includes reproduction light by two different tracks. The light intensity of the ambient light due to the L track (P _A +) is the sum of the error of the light intensity of the ambient light due to the L track (P _A -P _B ) and the error of the light intensity of the ambient light due to the R track (P _C -P _D ) The tracking error is obtained by dividing the sum of P _B ) and the light intensity (P _C + P _D ) of the ambient light by the R track.

In the absence of a tracking error, the Sc spot passes through the opening 155 and is not reflected by the reflective surface 156 so that it is not detected by the photodetector 170. In addition, only the S _L spot among the spots caused by the ambient light is detected through the first photo detector 172, and only the S _R spot is detected through the second photo detector 174. In this case, since P _A -P _B = 0 and P _C -P _D = 0, TE = 0 in Equation 1.

4 is a schematic diagram illustrating reproduction light detected through a photo detector when there is a tracking error.

Referring to FIG. 4, when a tracking error occurs, the reference light does not enter the correct point of the current track. Therefore, all of the reproduced light to be reproduced does not pass through the opening portion 155 and part of the reproduced light is reflected by the reflecting surface 156. In addition, due to the tracking error, the positions of the S _L2 spot, the S _L spot, the Sc spot, the S _R spot, and the S _R2 spot detected by the photodetector 170 are changed. Accordingly, since P _A -P _B ≠ 0 and P _C -P _D ≠ 0, it becomes TE ≠ 0 in Equation 1. The tracking error can be controlled by moving the optical pickup through the obtained TE value.

Hereinafter, Equation 1 for obtaining a tracking error will be described in detail.

To be suitable for finding tracking errors, symmetry about the origin must be ensured. Here, the origin refers to a case where there is no tracking error. Symmetry with respect to the origin indicates that the tracking error has the same shape, even if a tracking error occurs to the left or right of the current track. If the symmetry with respect to the origin is not guaranteed, the amount of movement of the optical pickup must be determined separately according to the sign of the tracking error, which makes the tracking control complicated.

In addition, in order to obtain a tracking error, the sensitivity must be small for the efficiency of reproduction light. Or it must be robust against variations in light intensity. That is, in the optical information processing apparatus using holography, the reproduction light is generated by diffraction by the reference light and the interference pattern, so the efficiency of the reproduction light detected by the photodetector 170 is not constant according to the interference pattern. If the tracking error value varies depending on the efficiency of the reproduction light, the tracking error must be re-specified according to the efficiency of the reproduction light, thereby complicating the tracking control.

The function of light intensity of each spot detected by the photo detector 170 is called f (x). Here, the function of light intensity for S _L2 spot is f _L2 (x), the function of light intensity for S _L spot is f _L (x), and the function of light intensity for Sc spot is fc (x) , The function of light intensity for the S _R spot is f _R (x) and the function of light intensity for the S _R2 spot is f _R2 (x).

The function of the light intensity for each spot can be assumed to be the same as the reproduction light passes through the fourth lens 129 which is a Fourier transform lens. F (x) = f _L2 (x) = f _L (x) = fc (x) = f _R (x) = f _R2 (x). In addition, the function of the light intensity is an even function in which the relation f (x) = f (-x) holds because of the Fourier transform.

5 is a diagram illustrating a function of light intensity when the tracking error of FIG. 4 occurs.

Referring to FIG. 5, a tracking error occurs when the spot moves by x0. In this case, an area is specified for the function of light intensity as shown in Equation 2 below.

Where x0 is the moving distance of the reproduced spot and a is the radius of the spot.

The direction of movement of the spot varies depending on the sign of x0. In the present embodiment, if the sign of x0 is positive, the spot moves to the right side with respect to the origin, and if the sign of x0 is negative, the spot moves to the left side with respect to the origin. Therefore, the movement of the spot shown in FIGS. 4 and 5 is a case where x0 is negative.

The light intensity detected by the photodiodes A, B, C, and D of the first and second photodetectors 172 and 174 according to the sign of x0 is represented by the efficiency of each spot and the region of equation (2). Can be.

When x0 is positive, the light intensity detected by the photodiodes A, B, C, and D is expressed by Equation 3 below.

Where η _L2 is the efficiency for the S _L2 spot, η _L is the efficiency for the S _L spot, ηc is the efficiency for the Sc spot, η _R is the efficiency for the S _R spot, and η _R2 is the efficiency for the S _R2 spot . Here, the superscript amount (+) represents the sign of x0.

When x0 is negative, the light intensity detected by the photodiodes A, B, C, and D is expressed by Equation 4.

,

으로 둘 수 있다. 또한, TE₁ = P_A - P_B, TE₂ = P_C - P_D 로 하면 수학식 3과 수학식 4를 다음의 수학식 5와 같이 나타낼 수 있다.If the reference light among the spots detected by the photo detector 170 is mostly irradiated only over the L track and the R track, the S _L2 spot and the S _R2 spot are hardly detected. therefore

,

Can be placed. Further, when TE ₁ = P _A -P _B and TE ₂ = P _C -P _D , Equations 3 and 4 can be expressed as in Equation 5 below.

으로 인해 대칭성이 없다. Tracking error of equation (5)

There is no symmetry.

In order to ensure symmetry, a new tracking error TE ₃ is defined as in Equation 6 below.

When TE ₃ of Equation 6 is again obtained from Equation 4, Equation 7 is obtained.

That is, regardless of the sign of x0, TE ₃ has the same absolute value. Thus, the symmetry of the tracking error is ensured.

Hereinafter, a tracking error according to the efficiency of the reproduction light will be described.

The tracking error (TE ₃ ) by equation (6) is not robust to variations in light intensity. That is, the efficiency η _L2 , η _L , η _R , and η _R2 for each spot may be represented by the efficiency η c for the Sc spot as shown in Equation 8 below.

Where k _L2 , k _L , k _R , k _R2 are constants. Substituting this into Equation 7, the following Equation 9 is obtained.

가 된다. 이를 수학식 9에 대입하면 다음의 수학식 10과 같다.The variation in the light intensity means that the efficiency of the regenerated light is changed so that the constants k _L2 , k _L , k _R , k _R2 change. In other words

Becomes Substituting this in Equation 9 is the same as Equation 10 below.

이다. 수학식 10으로부터

이다. TE₃'은 원점에 대해 대칭이기 때문이다. ΔTE₃는 Δk_LR에 의해 좌우되므로(dependant), TE₃'은 비록 원점에 대해 대칭이지만 재생광의 효율에 따라 값이 달라진다.here,

to be. From equation (10)

to be. This is because TE ₃ 'is symmetric about the origin. Since ΔTE ₃ is dependent on Δk _LR , TE ₃ ′, although symmetric about the origin, depends on the efficiency of the reproduction light.

Substituting the relationship of Equation 8 to the tracking error TE of Equation 1 is as follows.

At this time, the error of the tracking error according to the efficiency of the reproduction light is as follows.

here,

Since the phosphorus relation is established, it can be expressed as Equation 13 in Equation 12 below.

이므로, 결과적으로 재생광의 효율에 따른 트랙킹 에러의 오차 ΔTE 는 다음의 수학식 14와 같이 나타낼 수 있다.here,

As a result, the error ΔTE of the tracking error according to the efficiency of the reproduction light may be expressed as in Equation 14 below.

In other words, the upper bound of ΔTE is independent of the deviation Δk of the efficiency η of the reproduced spot, so the sensitivity is less sensitive to the efficiency of the reproduction light, so that even if the deviation occurs in the light intensity, it hardly affects the tracking error.

Hereinafter, simulation results for tracking error detection according to the present invention will be described.

6A to 6C are diagrams showing light intensity detected by each photodiode A, B, C, and D of the photodetector 170. The efficiency for each spot is all one. That is, η _L2 = η _L = η _R = η _R2 = 1.

6A shows that there is almost no difference in light intensity between the two photodiodes A and B of the first photodetector 172 when there is no tracking error, and the two photodiodes C, There is also almost no difference in light intensity detected in D).

6B illustrates the case where x0 is negative. Spots are detected biased to the left. In this case, part of the Sc spot caused by the main reproduction light is detected by the photodiode B.

6C shows the case where x0 is positive. Spots are detected biased to the right. In this case, part of the Sc spot caused by the main reproduction light is detected by the photodiode C.

7A to 7C are graphs showing tracking errors. FIG. 7A shows TE ₁ , FIG. 7B shows TE ₃ of Equation 7, and FIG. 7C shows TE of Equation 1.

Referring to Figure 7a to 7c, as x is changed in comparison to the asymmetric inde TE ₁ will depend on the origin, TE and TE ₃ is symmetrical about the origin.

8A to 8C are graphs showing each tracking error when the efficiency is different. At this time, it was set as (eta) _L2 = 1, (eta) _L = 0.4, (eta) _R = 0.7, (eta) _R2 = 1. FIG. 8A shows TE ₁ , FIG. 8B shows TE ₃ of Equation 7, and FIG. 8C shows TE of Equation 1.

8A to 8C, TE ₁ is asymmetrical from side to side with respect to the origin as x changes. Although TE ₃ is symmetric about the origin, there is a large difference in size due to the different efficiency compared to FIG. 7B. In contrast, TE is hardly changed in size compared to FIG. 7C. Therefore, it is not sensitive to the efficiency of reproduction light.

9A to 9C are graphs showing each tracking error when the efficiency is different. At this time, it was set as (eta) _L2 = 1, (eta) _L = 1.6, (eta) _R = 0.8, (eta) _R2 = 1. FIG. 9A shows TE ₁ , FIG. 9B shows TE ₃ of Equation 7, and FIG. 9C shows TE of Equation 1.

9A to 9C, as in the results of FIGS. 8A to 8C, TE is symmetric about the origin, and even if the efficiency is different, no big difference occurs.

Unlike the above-described embodiment, the present invention can be implemented in various modifications. For example, two or more light sources may be used without generating the reference light by one light source. In this case, the reference light may enter the recording area of the current track and other light sources may enter the recording area of the surrounding track to generate reproduction light. .

10 is a schematic diagram showing an optical information recording and reproducing apparatus according to another embodiment of the present invention. The same configuration as the embodiment of FIG. 1 is given the same reference numeral.

Referring to FIG. 10, the optical information recording and reproducing apparatus 300 includes an optical system 310, an ambient light separator 150, an optical information detector 160, an optical detector 170, and a signal processor 180. In the embodiment of FIG. 1, the other configuration for reproducing optical information except for the optical system 310 is the same, and thus, the optical system 310 will be described below.

The optical system 310 includes a light source 312, a light separator 313, a multiplexer 314, and a spatial light modulator 318. The light emitted from the light source 312 passes through the light separator 313 and is separated into reference light and information light. The reference light is reflected by the multiplexer 314 and incident on the optical information recording medium 150 at a predetermined angle.

The path of the information light is changed by the reflector 316 and is incident on the spatial light modulator 318. The spatial light modulator 140 optically modulates the input data information to generate a two-dimensional imaged data page, and projects the data page onto the incident information light to enter the optical information recording medium 200. When the reference light and the information light are incident at the same time, the resulting interference pattern is recorded on the optical information recording medium 200.

In order to reproduce data, when the information light is closed and only the reference light is incident, the reproduction light due to the interference pattern is generated.

As described above, according to the present invention, it is possible to detect a tracking error that is symmetrical with respect to the origin and sensitive to reproduction light efficiency. As a result, the BER due to optical information reproduction can be lowered, and the reliability of the optical information processing apparatus using holography can be improved.

Claims (8)

A tracking error detection method for detecting a tracking error from an optical information recording medium including a plurality of tracks, the method comprising: Irradiating reference light over a current track including a recording area in which data to be reproduced of the optical information recording medium is recorded, and a first peripheral track and a second peripheral track adjacent to the current track; Detecting first ambient light corresponding to the first peripheral track side and second ambient light corresponding to the second peripheral track side by being separated from the reproduction light reproduced by the reference light; And And a tracking error is detected by using the light intensity of the first ambient light and the light intensity of the second ambient light. The method of claim 1, Detecting the tracking error Tracking error detection for detecting the sum of the light intensity error of the first ambient light and the light intensity error of the second ambient light divided by the sum of the light intensity of the first ambient light and the light intensity of the second ambient light as the tracking error. Way. The method of claim 2, The light intensity error of the first ambient light is the light intensity difference of the first ambient light divided by two, And a light intensity error of the second ambient light is a difference in light intensity of the second ambient light divided by two. The method of claim 1, The first peripheral track is disposed on one side of the current track, And the second peripheral track is disposed on the other side of the current track. Detecting first ambient light by a first track of an optical information recording medium and second ambient light by a second track of the optical information recording medium; And Detecting as a tracking error a value obtained by dividing the sum of the light intensity of the first ambient light and the light intensity of the second ambient light by the sum of the light intensity error of the first ambient light and the light intensity error of the second ambient light. Tracking error detection method. The method of claim 5, And a track is disposed between the first track and the second track. An optical information reproducing apparatus for reproducing optical information from an optical information recording medium including a plurality of tracks, An optical system for irradiating reference light over a current track including a recording area in which data to be reproduced is recorded and a first peripheral track and a second peripheral track adjacent to the current track; An ambient light separator for separating the reproduction light reproduced by the reference light into main reproduction light reproduced in the recording area, first ambient light by the first peripheral track, and second ambient light by the second peripheral track; An optical information detector for detecting the optical information from the main reproduction light; A first photodetector for detecting the first ambient light; A second photodetector for detecting the second ambient light; And Receive the light intensity values detected by the first and second photodetectors, the light intensity of the first ambient light and the light intensity error of the second ambient light to the sum of the light intensity error of the first ambient light and the second ambient light And a signal processing unit for detecting a value obtained by dividing the sum of the light intensities of the lights with a tracking error. The method of claim 7, wherein And the ambient light separator passes the main reproduction light and reflects the first and second ambient light.

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