JPH10241212A - Phase transition type optical disk initialization device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase transition type optical disk initialization device keeping a precise focal state and performing uniform initialization ranging to a whole disk surface by preventing initializing high output laser beam from entering a focus controlling optical system. SOLUTION: For crystallizing the recording layer 103 of the optical disk 10 and initializing it, the initializing laser beam outgoing from a high output semiconductor laser 1 is made parallel light by a collimate lens 2, and luminous flux is expanded in the direction parallel to the activated layer of the semiconductor laser by an anamorphic optical system 3, and is focused on the optical disk 10 by an objective lens 9. For controlling this focal state, controlling laser beam outgoing from a low output semiconductor laser 4 is used. At this time, an angle between the optical axis of the initializing laser beam and the optical axis of the controlling laser beam is made toe prescribed angle to be made to image-form on different positions of the optical disk. By such a constitution, the uniform disk initialization enhancing light convergent efficiency while keeping the precise focal state becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk initialization apparatus for a phase-change type recording layer, and more particularly to an apparatus for initializing a large-capacity optical disk having a phase-change type recording layer.

[0002]

2. Description of the Related Art An optical disk having a phase change type recording layer is
The crystal layer of the recording material is irradiated with light to change the light-irradiated portion to an amorphous phase and record. Therefore, the recording layer must be a “crystal layer” in an initial state (a state where optical recording is possible). Since this recording layer is generally formed by sputtering or the like, the recording layer is in an “amorphous phase” at the stage of manufacture, and “initialization processing” for crystallizing the entire recording layer is necessary. In Japanese Patent Publication No. 7-52526,
There is disclosed a technique in which a laser beam is divided into two and then converged on an optical disk as a superposed interference beam. Here, the direction of the interference fringes is parallel to the circumferential direction of the disk, and the pitch of the interference fringes is set to 20 μm or less. As an effect, it is possible to prevent the occurrence of microcracks in the heat insulating layer during initialization. Also, light from a high-power semiconductor laser
It is focused on the recording layer as a light spot of 2 μm × 95 μm,
It has been reported that good initialization is possible by scanning the optical disk in the radial direction while rotating the optical disk (5th Phase Change Recording Research Group: Symposium Proceedings P
30, 1993).

On the other hand, there are the following optical disk initialization devices according to the prior art. While rotating a phase-change type optical disk, the light beam from the high-power semiconductor laser is converted into a parallel light beam by a collimating lens, and the anamorphic optical system expands the light beam only in the direction parallel to the active layer of the high-power semiconductor laser. While the focusing is being controlled by the optical disk, the light is focused on the optical disk by the objective lens, and the optical disk is moved in the radial direction by the feed mechanism. The parallel direction (longitudinal direction) of the active layer in the high-power semiconductor laser corresponds to the track orthogonal direction of the optical disk.

As a method using an optical system for focus control (wavelength λ ₁ ) and a high-power laser optical system for initialization (wavelength λ ₂ ), a method shown in FIG. Known as the technology. Figure 3 is a conceptual configuration diagram for explaining an example of a conventional phase change optical disk initialization apparatus in FIG, 10 is an optical disk, 80 a high transmittance mirror, 90 a condenser lens, L ₁ is the wavelength λ focus control optical system according to _one of the light beam, L ₂ is an optical system for initialization by the light flux of wavelength lambda _2. This method reflects a high transmittance mirror 80 that reflects at wavelength λ _{1 and} transmits at wavelength λ ₂ .
Irradiating the optical disc 10 with a high-power laser beam and a low-power laser beam for focusing using a condenser lens 90,
The initialization is performed while the optical disc 10 is in a focused state by the focus control in accordance with the relative movement of the optical disc 10 in the radial direction.

[0005]

SUMMARY OF THE INVENTION The aforementioned Japanese Patent Publication No. Hei 7-5
In the technique described in Japanese Patent No. 2526, a laser for focus control and a high-power laser for initialization are used, and laser beams having different laser wavelengths are used. Since a configuration is used in which light is condensed and interfered with a surface, a complicated optical system is required, which is a major problem.

Further, in the method using the focus control optical system and the initialization high-power laser optical system according to the configuration shown in FIG. 3, if λ ₁ and λ ₂ are not significantly different wavelengths, λ ₁ and λ ₂ are set. It becomes difficult to realize a high transmittance mirror for separation, and λ ₂ enters the focus control optical system, making it impossible to focus. Further, even if λ ₁ and λ ₂ are largely different, it is difficult to provide a high transmittance mirror that transmits 100% of λ ₂ , and reflects up to about 1%. Therefore, the output light of the high-power semiconductor laser light is ~ 2W
In the case of, if the reflectivity of the optical disk 10 is 〜１０10%,
Approximately ₂ mW of light of λ ₂ enters the focus control optical system, causing a focus control malfunction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and prevents a high-power laser beam for initialization from entering a focus control optical system using a low-power laser beam, thereby achieving focus control. It is an object of the present invention to provide a phase change type optical disk initialization apparatus capable of performing uniform initialization (crystallization of a recording layer) over the entire surface of a disk while achieving an accurate focusing state by an optical system.

[0008]

According to the first aspect of the present invention, there is provided a phase change type optical disk initialization apparatus for crystallizing a recording layer of a phase change recording type optical disk for initialization.
Rotating means for rotating while holding the optical disc;
A high-power semiconductor laser for oscillating the crystallization laser light for performing the crystallization, a collimating lens for collimating the oscillated crystallization laser light, and combining the collimated crystallization laser light with the optical disc. An objective lens for focusing, a low-output semiconductor laser that oscillates a control laser beam, focusing means for controlling the focusing using the control laser beam, and a relative position of the optical disc with respect to the objective lens. A phase change type optical disc initialization apparatus comprising: a feeding means for displacing a proper position in a radial direction of the optical disc, wherein a parallel direction of an active layer of the high-power semiconductor laser corresponds to a radial direction of the optical disc. The optical axis of the control laser beam and the optical axis of the crystallization laser beam make a predetermined angle with each other; It is characterized by the fact that the reflected light of the high power semiconductor laser is reflected by the high transmission mirror and enters the focus control optical system without disturbing the focus control operation. The initialization can be executed effectively while the in-focus state is maintained.

According to a second aspect of the present invention, in the first aspect, the optical axis of the objective lens and the optical axis of the crystallization laser beam incident on the objective lens form a predetermined angle with each other. It is characterized by the fact that the reflected light of the high-power semiconductor laser is reflected by the high transmission mirror and enters the focus control optical system to disturb the focus control operation,
The initialization can be executed effectively while an accurate focus state is maintained over the entire surface of the optical disk.

According to a third aspect of the present invention, in the second aspect of the present invention, the optical axis of the crystallization laser beam incident on the objective lens is set to be different from the optical axis of the objective lens by the crystallization laser beam on the optical disk surface. It is characterized by being inclined in the direction perpendicular to the longitudinal direction of the light imaging spot, so that the entire irradiation beam can be accurately focused, and uniform initialization over the entire surface of the disk can be executed more effectively It is made possible.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the crystallization laser beam is supplied to the high-power semiconductor laser in an optical path between the high-power semiconductor laser and the objective lens. An anamorphic optical system that expands in the direction corresponding to the parallel direction of the active layer is provided.The imaging spot shape becomes smaller in the longitudinal direction, and the optical power density increases, so initialization is easier. Can be executed.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the anamorphic optical system corresponds to the crystallization laser beam in an optical path in a direction parallel to an active layer of the high-power semiconductor laser. Characterized by using a pair of prisms refracted only in the direction of
Since the shape of the imaging spot becomes smaller in the longitudinal direction and the optical power density increases, initialization can be performed more easily.

According to a sixth aspect of the present invention, in the fourth or fifth aspect of the invention, the anamorphic optical system includes
Anamorphic optics, wherein a plurality of interchangeable optical elements having different light beam magnifications in a range of 4 times are provided, and any one of the plurality of optical elements is selected and used; The magnification of the system can be appropriately selected, so that more appropriate initialization can be performed.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the focal length of the collimating lens is in a range of 1 to 2 times the focal length of the objective lens. It is characterized by a synergistic effect of the magnification of the anamorphic optical system and the magnification of the imaging system by the collimating lens and the objective lens, which can improve the light collection efficiency on the optical disk, shorten the initialization processing time, and improve the quenching structure. The required optical disk can be effectively initialized.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, a rotating mechanism based on a CLV rotation method is used as the rotating means.
Since the output of the high-power semiconductor laser is set to be constant and uniform crystallization energy can be given to the entire surface of the optical disk to be initialized, crystallization can be performed uniformly over the entire surface of the disk.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects of the present invention, the optical disc comprises a lower protective layer, which is a dielectric layer, on a polycarbonate substrate;
a recording layer that is a b-Te layer, an upper protective layer that is a dielectric layer,
And a reflective layer, which is an alloy layer, is formed in this order, so that initialization can be performed more efficiently.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment) FIG. 1 shows an initialization apparatus according to the present invention. FIG. 1 is a conceptual diagram for explaining an embodiment of a phase change type optical disk initialization apparatus according to the present invention. In FIG. 1, 1 is a high-power semiconductor laser, 2 is a collimating lens, 3 is an anamorphic optical system, 4 is a low output semiconductor laser, 5 is a collimating lens, 6 is a polarization beam splitter, 7 is a 1/4 wavelength plate, 8 is a high transmittance mirror, 9 is an objective lens, 10 is an optical disk, 11 is a focus signal generating element, 12 Is an actuator, 13 is a rotation mechanism, 14 is a feed mechanism, 101
Is a polycarbonate substrate, 102 is a lower protective layer, 103
Is a recording layer, 104 is an upper protective layer, 105 is a reflective layer, S ₁
The imaging spot of the focus control laser beam, S ₂ is the image spot for initialization (for crystallization) laser beam.

High power semiconductor laser 1 (hereinafter high power LD)
) Is incident on the optical axis of the objective lens 9 while being inclined with respect to the optical axis of the objective lens 9 to form an image on the optical disk 10, and the entire recording layer of the optical disk 10 is rotated by rotation of the optical disk and relative movement in the radial direction. initialize. Optical disk 10
Has a phase change type recording layer 103 formed by sputtering film formation. Before the initialization, the recording layer is in an amorphous state, but changes to a crystalline state by the initialization. At the time of this initialization, the light beam from the low-power semiconductor laser 4 is made incident on the objective lens 9 using the high transmittance mirror 8 and focused on the optical disk 10 to perform the focus control. The in-focus state is maintained with the relative movement in the radial direction. At this time, the adjustment is performed so that the optical axis of the optical system for performing the focus control and the optical axis of the objective lens 9 coincide with each other.

The initialization device includes an optical disk rotation mechanism 13
, A high-power LD 1, a collimating lens 2 for collimating a light beam from a high-power semiconductor laser, an anamorphic optical system 3 having a lens function only in one direction, and a high-power LD 1 by the anamorphic optical system 3. The objective lens 9 for expanding the light beam in the parallel direction (longitudinal direction) of the active layer and condensing the parallel light beam from the anamorphic optical system 3 on the recording layer 103 of the optical disc 10 and the condensing position of the objective lens 9 are recorded. It has a focusing mechanism for adjusting to the layer 103 and a disk feed mechanism.

As an embodiment, it is needless to say that the anamorphic optical system 3 described above may be omitted (not shown, claims 1 and 2). Here, the parallel light beam from the anamorphic optical system 3 or the parallel light beam from the collimating lens 2 when the anamorphic optical system 3 is not provided is inclined with respect to the optical axis of the objective lens 9,
The light enters the objective lens 9 and is focused on the recording layer 103 of the optical disc. On the other hand, the light beam from the low-power semiconductor laser 4 for performing the focus control is mostly reflected by the high transmittance mirror 8 (high transmittance for the wavelength of the high-power semiconductor laser to 810 nm) (wavelength of the low-power semiconductor laser). Is incident on the objective lens 9 and forms an image on the surface of the recording layer 103 of the optical disc 10. At this time,
The imaging spot S _{1 of the} laser light for focus control and the imaging spot S ₂ of the laser light for initialization (for crystallization) form images at different positions on the surface of the recording layer 103 of the optical disk. The high-power LD 1 is used as a source of heat energy required for crystallization, and has a length in the direction parallel to the active layer (a direction corresponding to the minor axis direction in the elliptical far-field pattern) as compared with the low-power semiconductor laser 4. ) Is long.

FIG. 2 is a view showing an imaging spot of a laser beam for focus control and initialization according to the present invention. In FIG. 2, D is the radial direction of the optical disk, and S ₁ and S ₂ are those shown in FIG. Similarly, these are an imaging spot of a laser beam for focus control and an imaging spot of a laser beam for initialization (for crystallization). As shown, imaging spots S ₂ of the initialization laser beam radially of the optical disk 10, that is, long in the direction perpendicular to the track. The inclination direction of the parallel light beam from the high-power LD 1 with respect to the optical axis of the objective lens is most preferably inclined in a direction orthogonal to the longitudinal direction of the imaging spot of the initialization laser light, so that the entire irradiation beam is focused. (Claim 3). On the other hand, if the laser beam for initialization is inclined in the direction parallel to the longitudinal direction of the imaging spot, it becomes difficult to focus on the entire longitudinal direction of the irradiation beam.

More specifically, the rotating mechanism 13 shown in FIG. 1 holds and rotates a phase-change optical disk to be initialized, and the feed mechanism 14 controls the optical disk to be initialized with respect to the image forming position by the objective lens 9. 10 is relatively moved in the radial direction of the disk. A focusing mechanism using a low-power semiconductor laser including the focus signal generating element 11 and the actuator 12 performs focusing control for focusing a light beam from the high-power LD 1 on the recording layer of the optical disc. The anamorphic optical system 3 may be a combination of a pair of cylinder lenses having a lens function only in the parallel direction (longitudinal direction) of the active layer of the high-power LD 1 so as to form an afocal system. And a pair of prisms having a refraction function only in the direction parallel to the active layer of the high-power LD1.

Although the anamorphic optical system 3 can be fixedly incorporated with a single optical system in the apparatus, the anamorphic optical system 3 has different light fluxes within a range of about 2 to 4 times that can be exchanged with each other. It can be composed of a plurality of optical elements having a magnification. (Claim 6). The focal length of the collimator lens 2 for converting the laser beam from the high-power LD 1 into a parallel beam is preferably in the range of 1 to 2 times the focal length of the objective lens 9 (claim 7). The rotation mechanism 13 for rotating the optical disk 10 is preferably of a CLV (Constant Linear Velocity) rotation direction type. The initialization apparatus of the present invention can initialize various phase-change optical disks, and can initialize a phase-change optical disk 10 having a recording portion formed on a polycarbonate substrate 101, for example, as shown in FIG.
In this case, as a layer configuration of the recording unit, a lower protective layer 102 which is a dielectric layer of ZnS—SiO ₂ having a thickness of 1800 ° and an A layer having a thickness of 200 ° are formed on a polycarbonate substrate 101.
Recording layer 103 which is a g-In-Sb-Te layer, thickness: 2
Upper protective layer 104 which is a dielectric layer of ZnS-SiO ₂ of 50 °, reflective layer 1 which is an Al alloy layer having a thickness of 1000 °
The optical disk 10 having the optical disk 05 can be satisfactorily initialized (light for initialization is incident from the polycarbonate substrate side. Claim 9).

Next, the operation of the present invention will be described. The beam waist diameter when condensing a laser beam is inversely proportional to the beam system incident on the optical system. The larger the beam size, the smaller the focused beam waist diameter. . In semiconductor lasers, the length in the parallel direction of the active layer is larger than the width in the vertical direction,
The opening angle of the emitted light beam is small in the direction parallel to the active layer.
For this reason, when the laser beam from the semiconductor laser is made parallel by the collimating lens, the diameter of the parallel beam becomes large in the direction perpendicular to the active layer and becomes small in the parallel direction. Therefore, the shape of the image spot obtained by condensing the parallel light beam as it is by the objective lens is generally an elliptical shape whose major axis is in the parallel direction of the active layer. If the length in the longitudinal direction of the shape of the imaging spot becomes extremely long, the energy density of the light spot will decrease. As a result, in order to increase the energy density, an LD with high output power is required for initialization.
Therefore, in the present invention, an anamorphic optical system is arranged between the collimator lens and the objective lens, and the beam diameter in the parallel direction of the active layer is enlarged, so that the longitudinal length of the imaging spot is reduced. , The energy density increases. Further, since the optical disk initialization apparatus of the present invention has a focusing mechanism for each objective lens, each recording layer can always be irradiated with a spot of an appropriate size. Fluctuations are very small.

Hereinafter, a specific embodiment in which the parallel light beam from the high-power LD 1 is incident on the optical axis of the objective lens 9 at an angle of 10 ° in a direction orthogonal to the longitudinal direction of the image forming spot of the irradiation light beam will be described. I do. In FIG. 1, an optical disk 10 of a phase change type is held by a rotation mechanism 13 and rotates around a central axis. The rotation method of the rotation mechanism 13 is CLV.
The optical disk 10 is rotated so that the linear velocity at the image spot position accompanying the rotation is always constant (claim 7). The rotation mechanism 13 holding the optical disk 10 is fed at a constant speed in the radial direction of the optical disk 10 by the feed mechanism 14 together with the optical disk 10. The high-power LD 1 shown in FIG. 1 has an active layer having a vertical width of 1 μm and a parallel length of 200 μm, and has an output of 2 W. The high-power LD 1 is arranged so that the parallel direction of the active layer is in the radial direction of the optical disk 10 (the direction perpendicular to the track). The collimating lens 2 collimates the laser beam from the high-power LD 1 and has a focal length of 4.3 mm and an NA of 0.5. The anamorphic optical system 3 is composed of a pair of prisms having a refraction function only in the direction parallel to the active layer of the high-power LD 1 (left-right direction in FIG. 1). The light beam diameter is enlarged only in the parallel direction of the active layer.

An embodiment in which the parallel light beam from the collimator lens 2 is directly condensed by the objective lens 9 without using the anamorphic optical system 3 can be considered (not shown, claims 1 and 2). The high transmittance mirror 8 is a high transmittance mirror that transmits 99% of the laser beam from the high power LD 1.
The objective lens 9 focuses a parallel light beam on each recording portion of the optical disk 10, and has an effective diameter of 4 mm, a focal length of 4.3 mm, and an NA of 0.5. The semiconductor laser 4 has a low output, and a light beam emitted from the laser is converted into a parallel light beam by a collimating lens 5, and is combined by a polarizing beam splitter 6, a 板 wavelength plate 7, a focus signal generating element 11, and an actuator 12. Focus control is performed. When the focusing is performed by, for example, the astigmatism method, the focus signal generating element 11 includes an astigmatism generating optical element including a cylinder lens and a condensing lens and a four-division light receiving element. Initialization of the optical disc 10 is performed by turning on the high-power LD 1 while operating the focusing mechanism while the optical disc 10 is rotated by the rotating mechanism 13, condensing the laser light on the recording unit, and simultaneously sending the laser light by the feed mechanism 14. This is performed by feeding the optical disk 10 at a constant speed in the radial direction of the disk.

Next, a specific example in which an optical system with a magnification of 4 is used as the anamorphic optical system 3 will be described. The shape of the imaging spot of the laser beam for initialization from the high-power LD 1 focused on the optical disk 5 is 2 μm in the vertical direction of the active layer and 50 μm in the parallel direction as measured by a CCD camera.
Met. The linear velocity of the optical disk 10 at the position of the imaging spot of the initialization laser beam is set to 4 m / s, the initialization power by the high-power LD 1 (power on each recording unit: mW) and the optical disk by the feed mechanism 14 The initialization characteristics were examined by changing the feed rate of 10 (displacement in the radial direction per rotation: μm / r). Wavelength 780 after initialization
The semiconductor laser of nm, linear velocity 1.3 m / s, the recording frequency: recorded at f ₁ = 0.4 MHz, then, f ₂ =
C / N (d when overwriting at 0.72 MHz
B) and the erasure ratio (dB) were measured, and the state after initialization was observed with a microscope. The recording power at this time is 12
mW and bias power are 5 mW. The maximum output of the high-power LD1 corresponds to 700 mW in each recording section on the optical disk. Table 1 shows the results.

[0028]

[Table 1]

From these results, it was found that up to a feed speed of 30 μm / r, good initialization could be performed within the range of the output capability of the high-power LD1.

Next, a specific example in which an optical system with a magnification of 3 is used as the anamorphic optical system 3 will be described. The embodiment of the imaging spot with a CCD camera is 2 μm × 70 μm. Initialization characteristics were examined in the same manner as in the above example. Table 2 shows the results.

[0031]

[Table 2]

From this result, if the output of the high-power LD1 is maximized (700 mW in each recording section of the optical disk), good initialization can be performed for both layers even at a feed rate of 50 μm / r, and at least 40 μm / r. Can be surely initialized.

Next, a specific example in which an optical system with a magnification of 2 is used as the anamorphic optical system 3 will be described. The measured value of the light spot by the CCD camera is 2 μm × 95 μm. Initialization characteristics were examined in the same manner as in the above example. Table 3 shows the results.

[0034]

[Table 3]

From this result, if the output of the high-power LD1 is set to the maximum (700 mW in each recording unit), the feed speed becomes 70
Good initialization is possible for both layers even at μm / r, and initialization at least at 60 μm / r can be reliably performed.

In the above three embodiments, the focal lengths of the collimating lens 2 and the objective lens 9 are both 4.3 mm, so that the imaging magnification of the imaging system composed of the collimating lens 2 and the objective lens 9 is equal. Double the optical disk 1
The length of the imaging spot focused on zero is determined by the length of the active layer and the magnification of the anamorphic optical system 3 in the direction parallel to the active layer of the high-power LD 1. Accordingly, if the focal length of the collimating lens 2 is made longer than the focal length of the objective lens 9, the magnification of the imaging system becomes large.
Even if the magnification of the anamorphic optical system 3 is the same as the above three specific examples, it is possible to further enhance the light-collecting property of the image-forming spot focused on the optical disk and further increase the energy of the light spot.

Next, a specific example will be described in which an anamorphic optical system 3 having a magnification of 2 is used and a lens having a focal length of 8.6 mm and an NA of 0.5 is used as the collimating lens 2. The measured value of the imaging spot by the CCD camera is 2 μm × 51 μm, which is almost the same as the first specific example. Initialization characteristics were examined in the same manner as in the above example. Table 4 shows the results.

[0038]

[Table 4]

From this result, if the output of the high-power LD 1 is increased (550 mW or more in each recording section), the feed speed is 4
Good initialization is possible at 0 μm / r. By making the focal length of the collimating lens 2 larger than the focal length of the objective lens 9 in this way, the magnification of the imaging system is increased,
Further, by combining the magnification of the anamorphic optical system 3 with the magnification, it is possible to increase the light collection efficiency on the optical disk 10. However, if the focal length of the collimator lens 2 is too large, the proportion of the component of the light beam emitted from the high-power LD 1 that is converted into a parallel light beam becomes small, so that it is not possible to provide sufficient optical energy to the optical disc.
Therefore, the focal length of the collimating lens 2 is
Is preferably in the range of 1 to 2 times the focal length of (7).

Next, when the anamorphic optical system 3 is not used, the focal length is 8.6 as the collimating lens 2.
A specific example when a lens of mn, NA: 0.5 is used will be described. In this case, the measured value of the imaging spot by the CCD camera was 2 μm × 9.8 μm, and the initialization characteristics were examined in the same manner as in the above example. Table 5 shows the results.

[0041]

[Table 5]

From this result, if the output of the high-power LD1 is increased (650 mW or more in each recording section), the feed speed:
Good initialization is possible at 30 μm / r. In the specific example described above, the rotation mechanism 13 is a CLV rotation method,
Since the relative speed due to the rotation of the optical disk 10 with respect to the imaging spot is always constant, it is possible to always provide uniform light energy over the entire initialization area. Also,
The rotation speed of the optical disk 10 by the rotation mechanism 13 may be an equal angular speed, but in that case, the relative speed associated with the rotation of the optical spot and the optical disk becomes slower toward the inner circumference side of the disk. It is necessary to set the output of the high-power LD 1 so as to obtain energy for use.

In the embodiment described so far, the feed mechanism 1
Although the optical disk 10 is sent to the objective lens 9 in the radial direction of the disk by 4, the optical system for initialization may be displaced in the radial direction of the optical disk with respect to the optical disk. In order to reduce the time required for the initialization, it is preferable to use a higher output semiconductor laser as the high output LD1.

[0044]

【The invention's effect】

The optical axis of the laser beam for initialization of the high-power semiconductor laser and the optical axis of the laser beam for focus control are inclined, so that the reflected light of the high-power semiconductor laser is reflected by the high transmission mirror. The incident light does not enter the focus control optical system and disturbs the focus control operation, and the initialization can be executed effectively while maintaining the accurate focus state over the entire surface of the optical disc.

According to the third aspect of the present invention, the tilting direction of the optical axis of the initialization laser beam from the high-power semiconductor laser with respect to the optical axis of the objective lens is set to the direction orthogonal to the longitudinal direction of the imaging spot for initialization. The entire beam can be accurately focused, and uniform initialization over the entire surface of the disk can be performed more effectively.

According to the fourth and fifth aspects, since the luminous flux in the parallel direction of the active layer of the high-power semiconductor laser is expanded by the anamorphic optical system, the shape of the image spot becomes smaller in the longitudinal direction, and the optical power becomes higher. Due to the increased density, initialization can be performed more easily.

According to the sixth aspect, the magnification of the anamorphic optical system can be properly selected, and more appropriate initialization can be performed.

According to a seventh aspect of the present invention, the synergistic effect of the magnification of the anamorphic optical system and the magnification of the imaging system by the collimator lens and the objective lens can increase the light-collecting efficiency on the optical disk and shorten the initialization processing time. Also, it is possible to effectively execute the initialization of an optical disk that requires a more rapid cooling structure.

According to the eighth aspect of the present invention, since the output of the high-power semiconductor laser is set to be constant and uniform crystallization energy can be given to the entire surface of the optical disk to be initialized, the crystallization can be performed uniformly over the entire surface of the disk. it can.

The effect of claim 9: In particular, the recording layer has a high sensitivity A
Since g-In-Sb-Te is used, initialization can be performed more efficiently.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating an embodiment of a phase change type optical disk initialization apparatus according to the present invention.

FIG. 2 is a diagram showing imaging spots of laser light for focus control and initialization for the present invention.

FIG. 3 is a configuration conceptual diagram for explaining an example of a conventional phase-change optical disk initialization device.

[Explanation of symbols]

1. High power semiconductor laser, 2. Collimating lens, 3.
... anamorphic optical system, 4 ... low power semiconductor laser, 5 ... collimating lens, 6 ... polarizing beam splitter, 7 ... 1/4 wavelength plate, 8 ... high transmittance mirror, 9 ... objective lens, 10 ... optical disk, 11 ... Focus signal generating element, 12 ... Actuator, 13 ... Rotating mechanism, 14
.., Feed mechanism, 80, high transmittance mirror, 90, condenser lens, 101, polycarbonate substrate, 102, lower protective layer, 103, recording layer, 104, upper protective layer, 105, reflective layer, L _1, wavelength λ ₁ , A focus control optical system using a light beam of L ₂ , an initialization optical system using a light beam of a wavelength λ ₂ , S ₁ …
Focusing laser beam imaging spot, S ₂ … Initialization (crystallization) laser beam imaging spot.

Claims (9)

[Claims] 1. A phase change type optical disc initialization apparatus for crystallizing and initializing a recording layer of a phase change recording type optical disc, comprising: a rotating unit for rotating the optical disc while holding the optical disc; A high-power semiconductor laser that oscillates a crystallization laser beam for performing a laser beam, a collimating lens that collimates the oscillated crystallization laser beam, and a laser beam for focusing the collimated crystallization laser beam onto the optical disc. An objective lens, a low-power semiconductor laser that oscillates a control laser beam, focusing means for controlling the focusing using the control laser beam, and a relative position of the optical disc with respect to the objective lens. Feed means for displacing the optical disk in a radial direction, wherein the parallel direction of the active layer of the high power semiconductor laser is In a phase change type optical disk initialization device corresponding to a disk radial direction, an optical axis of the control laser light and an optical axis of the crystallization laser light form a predetermined angle with each other and are different from each other on the optical disk. A phase change type optical disk initialization device characterized in that a position is illuminated. 2. The phase according to claim 1, wherein an optical axis of the objective lens and an optical axis of the crystallization laser beam incident on the objective lens form a predetermined angle with each other. Changeable optical disk initialization device. 3. The optical axis of the crystallization laser beam incident on the objective lens is set in a direction perpendicular to the longitudinal direction of the imaging spot of the crystallization laser beam on the optical disk surface with respect to the objective lens optical axis. 3. The apparatus according to claim 2, wherein the apparatus is tilted. 4. An anamorphic device for expanding the crystallization laser beam in a direction corresponding to a direction parallel to an active layer of the high-power semiconductor laser in an optical path between the high-power semiconductor laser and the objective lens. 4. An apparatus according to claim 1, further comprising an optical system. 5. A pair of prisms as the anamorphic optical system, wherein the crystallization laser light in the optical path is refracted only in a direction corresponding to a direction parallel to an active layer of the high-power semiconductor laser. 5. The phase-change type optical disk initialization device according to claim 4, wherein said device is used. 6. An anamorphic optical system comprising:
5. A method according to claim 4, wherein a plurality of interchangeable optical elements having different light beam magnifications in a range of up to 4 times are prepared, and any one of the plurality of optical elements is selected and used. Or a phase change type optical disk initialization apparatus according to 5. 7. The collimating lens according to claim 1, wherein a focal length of the collimating lens is in a range of one to two times a focal length of the objective lens.
The phase change type optical disk initialization device according to the above. 8. The phase-change type optical disk initialization apparatus according to claim 1, wherein a rotation mechanism based on a CLV rotation method is used as said rotation means. 9. The optical disk according to claim 1, wherein a lower protective layer, which is a dielectric layer, is formed on a polycarbonate substrate by using a Ag-In-Sb-
9. The phase change optical disk according to claim 1, wherein a recording layer as a Te layer, an upper protective layer as a dielectric layer, and a reflective layer as an alloy layer are formed in this order. Device.