JP3600016B2 - Optical information recording / reproducing device and optical pickup - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical information recording / reproducing apparatus for recording and reproducing information on a recordable optical disk and an optical pickup used for the apparatus.
[0002]
[Prior art]
Write-once optical disks and rewritable optical disks are known as optical disks on which a user can arbitrarily record information. Generally, a dye-based or metal-based optical disk is used as a write-once type, and a magneto-optical optical disk, a phase-change type optical disk, or the like is used as a rewritable type. This is an optical disk of a type in which information pits are formed by heat corresponding to the information and information is recorded. Therefore, it is very important to record information with an optimal laser power for accurate information recording.
[0003]
[Problems to be solved by the invention]
However, the determination of the optimum laser power at the time of recording presupposes that recording is performed under the same conditions and environment for all recording portions of the optical disk. Therefore, when recording is performed under a condition different from that at the time of determining the recording power, the power at the time of the actual recording operation is not always the optimum value. For this reason, pits of sufficient quality may not be formed, and the reproduction signal is degraded.
[0004]
The main reason why the recording power does not reach the optimum value is that the optical axis of the laser beam does not become perpendicular to the recording surface of the optical disk due to warpage, distortion, inclination, or the like of the optical disk. That is, when there is an inclination angle (hereinafter, referred to as a tilt angle) of the laser beam on the recording surface of the optical disk with respect to the optical axis, a wavefront aberration (mainly coma aberration) occurs in the laser light. Since the laser cannot be uniformly focused on the recording surface due to the influence of the wavefront aberration caused by the tilt angle, the laser power is not evenly applied to the recording surface, and pits are not sufficiently formed or the pits are deformed. Problems arise. A similar problem also occurs due to spherical aberration caused by a difference in substrate thickness and astigmatism caused by an optical system in the optical pickup.
[0005]
Accordingly, it is an object of the present invention to provide an optical information recording / reproducing apparatus capable of correcting the influence of wavefront aberration and always performing good recording and reproducing. It is another object of the present invention to provide an optical pickup capable of reducing the influence of wavefront aberration generated during reproduction or recording of an optical disc and performing good recording and reproduction.
[0006]
[Means for Solving the Problems]
According to an aspect of the present invention, there is provided an optical information recording / reproducing apparatus for recording / reproducing information on / from an optical disk, wherein a laser for irradiating the optical disk with a laser beam and a tilt angle of the optical disk are detected. driving a detector, an aberration correcting means for correcting the wavefront aberration due to the tilt angle by giving a predetermined phase difference to said laser beam, said aberration correcting means based on said tilt angle detected and driving means, the compensation power to compensate for the decrease of the recording power by the residual wavefront aberration can not be corrected by the aberration correcting means, adding to be applied to the optimal power at the time of recording in accordance with the tilt angle detected Laser control means.
[0007]
According to the operation of the first aspect of the invention, good recording or reproduction can be always performed regardless of the tilt angle of the optical disk. Furthermore, since the wavefront aberration caused by the tilt angle is compensated by increasing the laser power only by the decrease in the recording power due to the residual wavefront aberration that cannot be completely corrected by the aberration corrector, it is not necessary to increase the laser power more than necessary and to reduce the power. Power drive becomes possible.
[0008]
According to a second aspect of the present invention, there is provided the optical information recording / reproducing apparatus according to the first aspect, wherein the aberration correction unit is divided into a shape corresponding to a wavefront aberration distribution caused by the tilt angle. And a liquid crystal layer whose refractive index changes according to an applied voltage.
[0009]
According to the operation of the second aspect of the invention, it is possible to efficiently correct the wavefront aberration caused by the tilt angle of the optical disk. Furthermore, since a mechanism for moving the optical pickup itself to eliminate the tilt angle is not required, the size of the optical pickup can be reduced.
[0012]
The invention of claim 3, wherein in order to solve the above described problems is the optical information reproducing apparatus according to claim 1, further comprising a storage means for storing laser control amount corresponding to the tilt angle, the laser control unit, The power of the laser is controlled based on a laser control amount corresponding to the detected tilt angle stored in the storage unit.
[0013]
According to the third aspect of the invention, the laser power according to the tilt angle can be easily calculated.
[0014]
According to a fourth aspect of the present invention, there is provided a laser, an objective lens, a liquid crystal panel for correcting a wavefront aberration, a liquid crystal panel control unit for controlling the liquid crystal panel, and a laser control for controlling the laser. and means, wherein the laser control means, the compensation power to compensate for the decrease of the recording power by the residual wavefront aberration can not be corrected by the liquid crystal panel is added to the optimal power at the time of recording in accordance with the tilt angle And controlling the output of the laser by applying the laser beam.
[0015]
According to the operation of the fourth aspect of the present invention, compensation is made by increasing the laser power only by the decrease in the recording power due to the residual wavefront aberration that cannot be completely corrected by the aberration correcting means. Therefore, compared with the case where no liquid crystal panel is used, it is not necessary to increase the laser power, and low-power driving can be performed.
[0016]
According to a fifth aspect of the present invention, there is provided an optical pickup according to the fourth aspect, wherein the liquid crystal panel has a transparent electrode divided corresponding to a wavefront aberration distribution on a pupil plane of the objective lens. It is characterized by.
[0017]
According to the operation of the fifth aspect of the present invention, it is possible to simplify the production of the liquid crystal panel and to efficiently correct the wavefront aberration.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment according to the present invention will be described with reference to FIGS. The embodiment described below is an embodiment for correcting a wavefront aberration caused by a tilt angle of an optical disc in a radial direction.
[0019]
First, the overall configuration of the optical information recording / reproducing apparatus according to the embodiment will be described with reference to FIG.
[0020]
As shown in FIG. 1, the optical information recording / reproducing apparatus S of the embodiment includes a spindle motor 8 for rotating the optical disk 4 at a predetermined rotation speed, and a light beam while correcting the generated wavefront aberration using a liquid crystal panel. And an optical pickup 13 that outputs a detection signal Sr corresponding to the recording information on the optical disk 4 based on the reflected light, and a reproducing unit that reproduces the recording information based on the detection signal Sr and outputs it as a reproduction signal Sp. And a reproduction control unit 20.
[0021]
The optical pickup 13 includes a laser diode 1 as a light source, a beam splitter 2, an objective lens 3, a condenser lens 6, a light receiver 7 as a light receiving unit, a liquid crystal panel 10 as an aberration correcting unit, a light beam And a tilt sensor 5 as detecting means for detecting a tilt angle of the optical disc 4 to which the light is irradiated.
[0022]
On the other hand, the reproduction control unit 20 includes a CPU 21 that decodes the received light output Sr and encodes a recording signal Sw supplied from the outside, an A / D converter 22 that digitizes the output of the tilt sensor 5, and a liquid crystal panel. The control unit 10 includes a liquid crystal panel control unit 23 for controlling the power supply 10 and a laser control unit 24 for controlling the output power of the laser diode 1.
[0023]
Next, the overall operation will be described.
[0024]
The optical disk 4 is driven to rotate at a predetermined rotation speed by a spindle motor 8. At this time, the light beam emitted from the laser diode 1 is partially reflected by the beam splitter 2 and enters the liquid crystal panel 10. Then, a phase difference for correcting the wavefront aberration when transmitting through the liquid crystal panel 10 is given, and thereafter, the light is focused on the information recording surface of the optical disc 4 by the objective lens 3.
[0025]
Next, the light beam reflected on the information recording surface of the optical disk 4 passes through the objective lens 3 and the liquid crystal panel 10 again, passes through the beam splitter 2, and is collected on the light receiver 7 via the condenser lens 6. Is lighted. The reflected light of the light beam received by the light receiver 7 is converted into a detection signal Sr, which is an electric signal, by the light receiver 7 and supplied to the CPU 21. After that, the CPU 21 performs a predetermined demodulation process or the like, and outputs a reproduction signal Sp corresponding to the recorded information recorded on the optical disc 4 to a reproduction circuit (not shown).
[0026]
The recording signal Sw supplied from the outside is supplied to the CPU 21. The CPU 21 controls the laser diode 1 through the laser control unit 24 based on Sw to modulate the laser light.
[0027]
In parallel with the above operation, the tilt angle in the radial direction of the optical disc 4 is detected by the tilt sensor 5 and output as a tilt detection signal Stil which is an analog signal. Then, the tilt detection signal Stil is digitized in the A / D converter 22 and input to the CPU 21.
[0028]
Here, the tilt sensor 5 has one light emitting unit and two light receiving units, and is arranged to detect a tilt angle of the optical disc 4 in the radial direction. The liquid crystal panel control unit 23 cancels a radial aberration correction amount (that is, a wavefront aberration caused by a tilt angle in the radial direction) for each region described later of the liquid crystal panel 10 based on the tilt detection signal Stil supplied from the CPU 21. Therefore, a phase difference to be given to the light beam passing through the liquid crystal panel 10 is calculated. The detailed configuration of the liquid crystal panel control unit 23 will be described later.
[0029]
The laser controller 24 calculates the output power of the laser diode 1 based on the tilt detection signal Stil supplied from the CPU 21. The detailed configuration of the laser control unit 24 will also be described later.
[0030]
Next, the configuration and operation of the liquid crystal panel 10 of the present invention will be described with reference to FIGS.
[0031]
FIG. 2 is a longitudinal sectional view of the liquid crystal panel 10. In the liquid crystal panel 10 as the aberration correcting means of the embodiment, the alignment films 10e and 10f for giving a predetermined molecular alignment to the liquid crystal 10g are formed with the liquid crystal 10g containing the liquid crystal molecules M interposed therebetween. A pair of transparent electrodes 10c and 10d made of ITO (Indium-tin Oxide; indium tin oxide) and the like are formed on the outside of each of 10f. Further, glass substrates 10a and 10b as protective layers are formed on the outermost sides.
[0032]
The transparent electrode 10c is divided into regions corresponding to the distribution of the wavefront aberration caused by the tilt angle of the optical disc as described later, and is an electrode for correcting the wavefront aberration caused by the tilt angle in the radial direction.
[0033]
The liquid crystal 10g has a so-called birefringence effect, in which the refractive index differs between the optical axis direction of the liquid crystal molecules M and the direction perpendicular thereto, and a voltage applied to the transparent electrodes 10c and 10d is used. By changing the value, as shown in FIGS. 2A to 2C, the direction of the liquid crystal molecules M can be freely changed from the horizontal direction to the vertical direction.
[0034]
Next, the configuration of the transparent electrodes 10c and 10d will be described with reference to FIG. The transparent electrode 10c is divided into five regions 30a, 30b, 31a, 31b and 32 arranged in line symmetry as shown in FIG. 3, and the respective regions are insulated from each other. In these regions, the regions 30a and 30b are driven by the same drive signal Slp, and the regions 31a and 31b are driven by the same drive signal Slp. The reason why the transparent electrode 10c is divided into the shapes shown in FIG. 3 is to make the shape substantially the same as the distribution of the wavefront aberration caused by the tilt angle of the optical disc.
[0035]
The size of the entire transparent electrode 10c is set so that the incident range SP of the light beam to the transparent electrode 10c becomes the range shown in FIG. The transparent electrode 10d is an undivided counter electrode and is grounded.
[0036]
FIG. 4 shows a wavefront aberration distribution on the pupil plane of the objective lens when the recording surface of the optical disk is tilted by 1 degree with respect to the optical axis of the laser beam. In FIG. 4, reference numeral 11 denotes a beam diameter of the laser beam, and a wavefront aberration distribution on the pupil plane of the objective lens is set to a range of 50 nm above and below the area A having a range of the wavefront aberration difference value Wrms from −25 nm to +25 nm. This is divided into regions A to K indicated by width.
[0037]
X 2 ′ -X 2 in the figure is an axis corresponding to the tilt direction of the optical disc, and when a tilt angle occurs in the radial direction of the optical disc, X 2 ′ -X 2 is the radial direction of the optical disc; When a tilt angle occurs in the tangential direction of the optical disk, X2'-X2 is the tangential direction of the optical disk.
[0038]
FIG. 5 shows the amount of wavefront aberration on the X2'-X2 axis in FIG. The distribution of the wavefront aberration itself has a constant distribution irrespective of the magnitude of the tilt angle, and the amount of the wavefront aberration changes according to the magnitude of the tilt angle. Referring to FIG. 5, the peak value of the curve shown in FIG. 5 increases as the tilt angle increases, and decreases as the tilt angle decreases.
[0039]
In the present embodiment, the divided shape of the transparent electrode 10c is a shape similar to the wavefront aberration distribution in FIG. Thus, by applying an appropriate voltage to each area of the transparent electrode 10c so as to cancel the wavefront aberration caused by the tilt angle of the optical disc, a phase difference is given to the light beam, and the influence of the wavefront aberration caused by the tilt angle is reproduced. To a range that does not affect. That is, voltage control is performed for each divided region of the transparent electrode 10c to change the direction of the liquid crystal molecules M, and the refractive index of each divided region is changed to give a phase difference to the light beam, thereby generating a wavefront generated when the disk 5 is tilted. It corrects the aberration. The principle of the correction of the wavefront aberration caused by the tilt angle of the optical disk is described in detail in JP-A-10-20263.
[0040]
As described above, the shape of each area shown in FIG. 3 is set based on the wavefront aberration distribution when the recording surface of the optical disc 4 shown in FIG. 4 is tilted. There are five regions corresponding to the case where the aberration is approximated by five values.
[0041]
The region corresponding to the region 32 is a region including a region where the value of the wavefront aberration is 0, and the region of the transparent electrode 10c corresponding to the region 31b and the region of the transparent electrode 10c corresponding to the region 30b have symmetric shapes. And the value of the phase difference given to the transmitted light beam has the opposite polarity. Further, the area of the transparent electrode 10c corresponding to the area 30a and the area of the transparent electrode 10c corresponding to the area 31a have symmetric shapes, and the values of the phase difference given to the transmitted light beam have opposite polarities.
[0042]
If the number of divisions of the transparent electrode 10c (that is, the number of the regions) is further increased and the transparent electrode 10c is subdivided, the wavefront aberration caused by the tilt angle of the optical disk 4 can be completely canceled. However, if the number of divisions is increased by, for example, dividing the transparent electrode 10c in a grid pattern, it is necessary to control and apply a drive signal for each of the divided areas, and to create the transparent electrode 10c and to apply lead lines and the like. It becomes difficult to create wiring.
[0043]
Therefore, in the liquid crystal panel 10 of the present invention, the transparent electrode 10c can be easily formed by making the divided shape similar to the wavefront aberration distribution as shown in FIG. The wavefront aberration is configured to be corrected efficiently.
[0044]
Next, the driving of the liquid crystal 10g by applying the driving signal Slp to each transparent electrode 10c will be described with reference to FIGS.
[0045]
First, the configuration of the liquid crystal panel control unit 23 will be described. FIG. 6 is a block diagram showing the configuration of the liquid crystal panel control unit 23. The liquid crystal panel control unit 23 outputs a liquid crystal driver 230 that calculates a voltage to be applied to the liquid crystal panel according to the magnitude of the tilt angle supplied from the CPU 21 and a drive signal Slp having an amplitude corresponding to the input voltage. And a GND 232 which is a ground terminal of the transparent electrode 10d.
[0046]
The liquid crystal driver 230 outputs Vc as a reference voltage and Va and Vb as voltages according to the tilt angle. The liquid crystal driver 230 has a memory in which the relationship between the tilt angle and the voltage corresponding to the tilt angle is stored in advance, and Va and Vb are determined by referring to the contents of this memory. Note that Va and Vb are set so as to give a wavefront aberration having a polarity opposite to the wavefront aberration distribution when the recording surface of the optical disc 4 is inclined.
[0047]
Va output from the liquid crystal driver 230 becomes a voltage applied to the regions 30a and 30b of the transparent electrode 10c, and Vb becomes a voltage applied to the regions 31a and 31b of the transparent electrode 10c and is supplied to the amplitude modulator 231. The reference voltage Vc becomes a voltage supplied to the area 32 of the transparent electrode 10c and is supplied to the amplitude modulator 231.
[0048]
The amplitude modulator 231 outputs a rectangular wave having an amplitude according to the input voltage. This rectangular wave is applied as a drive signal Slp to the regions 30a, 30b, 31a, 31b, 32 of the transparent electrode 10c, respectively. The amplitude modulator 231 outputs a rectangular wave with a large amplitude when the input voltage is large, and outputs a rectangular wave with a small amplitude when the input voltage is small.
[0049]
FIG. 7 shows the amount of phase difference given by the liquid crystal panel 10 on the X2'-X2 axis when the wavefront aberration caused by the tilt angle of the optical disk is that shown in FIG.
[0050]
In FIG. 7, the solid line shows the wavefront aberration caused by the tilt angle of the optical disc on the pupil plane of the objective lens, and is the same as FIG. The dotted line is the phase difference provided by the liquid crystal panel 10. From the dotted line on the X2 side on the left side of the drawing, (1) is a phase difference given by the region 30b of the liquid crystal panel 10, and (2) is a phase difference given by the region 31a of the liquid crystal panel 10. (3) is the phase difference given by the region 30a of the liquid crystal panel 10, and (4) is the phase difference given by the region 31b of the liquid crystal panel 10.
[0051]
FIG. 8 shows a wavefront aberration distribution on the pupil plane of the objective lens when the liquid crystal panel 10 is driven. It can be seen that the wavefront aberration caused by the tilt angle of the optical disk is canceled by the phase difference given by the liquid crystal panel 10.
[0052]
8 indicate residual wavefront aberrations that could not be corrected by the liquid crystal panel 10. This residual wavefront aberration is due to the fact that the divisional shape of the transparent electrode 10c of the liquid crystal panel 10 does not match the actual wavefront aberration distribution (the wavefront aberration distribution on the pupil plane of the objective lens shown in FIG. 4).
[0053]
This residual wavefront aberration does not cause any particular problem when reproducing the optical disk, but causes a decrease in the recording power of the light beam when recording information on the optical disk.
[0054]
FIG. 9 is a diagram showing the relationship between the tilt angle of the optical disc and the energy of the recording beam. The horizontal axis indicates the tilt angle [deg] of the optical disc, and the vertical axis indicates the recording beam energy and the tilt angle is 0 deg. Is set to 1. The NA of the objective lens is 0.6, and the wavelength of the laser beam is 635 nm.
[0055]
In FIG. 9, the solid line indicates a case where the liquid crystal panel does not perform the wavefront aberration correction, and the dotted line indicates a case where the liquid crystal panel performs the wavefront aberration correction. By correcting the wavefront aberration by the liquid crystal panel, the energy of the recording beam that can be used for recording is greatly improved. However, since the transparent electrodes of the liquid crystal panel do not have the same pattern as the actual wavefront aberration distribution, even when the liquid crystal panel is used, the recording energy decreases as the tilt angle increases. A decrease in recording power leads to an increase in jitter because an appropriate recording mark (pit) cannot be formed.
[0056]
In the present invention, the decrease in recording power due to residual wavefront aberration that cannot be completely corrected by the liquid crystal panel is eliminated by adjusting the laser output. That is, most of the wavefront aberration is corrected using the liquid crystal panel (from the solid line to the dotted line in FIG. 9), and the decrease in the recording power due to the residual wavefront aberration that cannot be corrected by the liquid crystal panel is compensated by adjusting the laser output. This is done (from the dotted line in FIG. 9 to 1.0).
[0057]
Hereinafter, laser output control according to the laser tilt angle will be described.
[0058]
FIG. 10 is a block diagram showing a configuration of the laser control unit 24 of FIG. The laser control unit 24 calculates the optimum power of the laser beam according to the control signal supplied from the CPU 21 and the liquid crystal panel according to the tilt angle supplied from the CPU 21. A compensating power calculating unit 241 for calculating a compensating power for compensating for a decrease in recording power due to a residual wavefront aberration that cannot be completed; an adder 242 for adding outputs of the optimal power calculating unit 240 and the compensating power calculating unit 241; And a laser driver 243 that outputs a laser control signal Sld based on the output from the adder 242.
[0059]
Next, the operation will be described.
[0060]
The optimum power calculation unit 240 calculates the optimum recording power at the time of recording or reproduction based on the control signal supplied from the CPU 21. The compensation power calculator 241 calculates compensation power according to the tilt angle based on the information on the tilt angle supplied from the CPU 21. When the tilt angle is 0 deg, there is no reduction in recording power due to wavefront aberration caused by the tilt angle, so that no compensation power is required. Also, no compensation power is required when reproducing the optical disk.
[0061]
Further, the compensation power calculation unit 241 includes a memory in which the relationship between the tilt angle and the compensation power is stored in advance, and the compensation power corresponding to the tilt angle supplied from the CPU 21 is obtained by referring to the memory.
[0062]
FIG. 11 shows the relationship between the tilt angle and the compensation power stored in the memory. FIG. 11 (a) is for changing the compensation power linearly according to the tilt angle, and the compensation power monotonically increases as the tilt angle increases. Further, as shown in FIG. 11B, the compensation power may be set stepwise as the tilt angle increases.
[0063]
The optimum power and the compensation power calculated by the optimum power calculation unit 240 and the compensation power calculation unit 241 are added by the adder 242 and supplied to the laser driver 243. Therefore, the laser driver 243 outputs the laser control signal Sld for driving the laser diode 1 with the recording power that allows for the decrease in the recording power due to the wavefront aberration caused by the tilt angle.
[0064]
By controlling the liquid crystal panel and the laser diode as described above, good recording can always be performed regardless of the tilt angle of the optical disc during recording. Further, since most of the wavefront aberration can be corrected by the liquid crystal panel, the laser power for compensating for the decrease in the recording power due to the residual wavefront aberration that cannot be completely corrected by the liquid crystal panel can be reduced.
[0065]
In this embodiment, the tilt angle is detected by the tilt sensor. However, the tilt angle may be detected by using a reproduction signal (Sr or Sp) from an optical disk as disclosed in Japanese Patent Application Laid-Open No. H10-97728.
[0066]
Furthermore, the present invention has been described with respect to the case where the liquid crystal panel for correcting the wavefront aberration caused by the tilt angle is used, but not only the wavefront aberration caused by the tilt angle but also the spherical aberration caused by the thickness of the substrate of the optical disc. The present invention can be applied to a liquid crystal panel for correcting astigmatism caused by an optical system in an optical pickup.
[0067]
【The invention's effect】
According to the first aspect of the present invention, the power of the laser is changed based on the detected tilt angle, so that good recording or reproduction can always be performed regardless of the tilt angle of the optical disk. Furthermore, since the wavefront aberration caused by the tilt angle is compensated by increasing the laser power only by the decrease in the recording power due to the residual wavefront aberration that cannot be completely corrected by the aberration corrector, it is not necessary to increase the laser power more than necessary and to reduce the power. Power drive becomes possible.
[0068]
According to the second aspect of the present invention, it is possible to efficiently correct the wavefront aberration caused by the tilt angle of the optical disc. Further, since a mechanism for moving the optical pickup itself to eliminate the tilt angle is not required, the size of the optical pickup can be reduced.
[0070]
According to the operation of the third aspect of the invention, the laser power according to the tilt angle can be easily calculated.
[0071]
According to the fourth aspect of the present invention, the compensation is made by increasing the laser power only by the decrease in the recording power due to the residual wavefront aberration that cannot be completely corrected by the liquid crystal panel. Therefore, it is not necessary to increase the laser power as compared with when a liquid crystal panel is not used, and low-power driving is possible.
[0072]
According to the fifth aspect of the present invention, it is possible to simplify the production of the liquid crystal panel and to efficiently correct the wavefront aberration.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of an optical information recording / reproducing apparatus according to an embodiment.
FIGS. 2A and 2B are vertical cross-sectional views illustrating a configuration of a liquid crystal panel. FIG. 2A is a vertical cross-sectional view illustrating a liquid crystal in which liquid crystal molecules are in a horizontal state, and FIG. (C) is a longitudinal sectional view showing a liquid crystal in which liquid crystal molecules are vertical.
FIG. 3 is a plan view illustrating a configuration of a transparent electrode according to the embodiment.
FIG. 4 is a plan view showing a distribution of wavefront aberration caused by a tilt angle of the optical disc.
FIG. 5 is a diagram illustrating the magnitude of wavefront aberration caused by a tilt angle of an optical disc.
FIG. 6 is a block diagram illustrating a configuration of a liquid crystal panel control unit.
FIG. 7 is a diagram showing the magnitude of a wavefront aberration caused by a tilt angle of an optical disc and a phase difference given by a liquid crystal panel.
FIG. 8 is a diagram illustrating the magnitude of residual wavefront aberration that cannot be corrected by a liquid crystal panel.
FIG. 9 is a diagram illustrating a relationship between a tilt angle of an optical disc and recording beam energy.
FIG. 10 is a block diagram illustrating a configuration of a laser control unit.
FIG. 11 is a diagram illustrating a relationship between a tilt angle and compensation power.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Laser diode 2 ... Beam splitter 3 ... Objective lens 4 ... Optical disk 5 ... Tilt sensor 6 ... Condensing lens 7 ... Light receiver 8 ... Spindle motor 10 ... Liquid crystal panel 13 ... Optical pickup 20 ... Reproduction control part 21 ... CPU
22 A / D converter 23 Liquid crystal panel controller 24 Laser controllers 10a and 10b Glass substrates 10c and 10d Transparent electrodes 10e and 10f Alignment film 10g Liquid crystals 30a, 30b, 31a, 31b, 32 ... SP: light spot M: liquid crystal molecule Sr: detection signal Sw: recording signal Sp: reproduction signal Sld: laser control signal Slp: driving signal

Claims (5)

In an optical information recording / reproducing apparatus for recording / reproducing information on / from an optical disk, a laser for irradiating the optical disk with a laser beam, a detecting unit for detecting a tilt angle of the optical disk, and a predetermined phase difference to the laser beam are provided. an aberration correcting means for correcting the wavefront aberration due to the tilt angle, and drive means for driving the aberration correcting means on the basis of the tilt angle detected residual wavefront aberration can not be corrected by the aberration correcting means by the compensation power to compensate for the decrease in the recording power, the detected optical information recording and having a laser control means for applying by adding the optimal power at the time of recording in accordance with the tilt angle Playback device. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the aberration correction unit includes an electrode divided into a shape corresponding to a wavefront aberration distribution due to the tilt angle, and a liquid crystal whose refractive index changes according to an applied voltage. An optical information recording / reproducing apparatus comprising at least a layer. In the optical information reproducing apparatus according to claim 1, further comprising a storage means for storing laser control amount corresponding to the tilt angle, the laser control unit, the tilt angle detected is stored in the storage means An optical information recording / reproducing apparatus, wherein the power of the laser is controlled based on a corresponding laser control amount. A laser, an objective lens, a liquid crystal panel for correcting wavefront aberration, a liquid crystal panel control unit for controlling the liquid crystal panel, and a laser control unit for controlling the laser, wherein the laser control unit includes the liquid crystal panel. the compensation power for by residual wavefront aberration in can not be corrected compensate for the decrease of the recording power, controls the output of the laser by applying by adding the optimal power at the time of recording in accordance with the tilt angle, that Optical pickup featured. 5. The optical pickup according to claim 4, wherein the liquid crystal panel has a transparent electrode divided according to a wavefront aberration distribution on a pupil plane of the objective lens.

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