JP2001043574A - Reference disk, method for adjusting optical pickup and method for adjusting disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify an adjusting operation by forming two information recording surfaces corresponding to thicknesses of two light transmission layers having thicknesses different from each other which are provided in a first and second region which are formed by dividing an original information recording surface into two concentric circular parts. SOLUTION: A rugged shape 2 and a reflection film 3 are formed on an outer peripheral region AR1 on one surface of A glass master disk 1 having the same thickness as a thickness of a light transmission layer of a DVD and a diameter having the same length as a length of a diameter of the DVD. A rugged shape 5 and a reflection film 6 are formed on one surface of a disk substrate 4 having a diameter having the same length as a length of a diameter of a compact disk and a thickness equal to a thickness obtained by subtracting a thickness of the glass master disk 1 from a thickness of a light transmission layer of the compact disk. A UV-ray effect resin is dropped onto the disk substrate 4 and the glass master disk 1 is closely adhered to the disk substrate 4. And then the disk substrate 4 and the glass master disk 1 are integrated by an ultraviolet ray UV. Therefore, a standard disk 11 is obtained, having two light transmission layers having thicknesses different from each other in two regions AR1 and AR2 which an information recording surface is concentric circularly divided into.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a reference disk and an optical pickup and an adjustment method for an optical disk device, for example, to an optical pickup device used for reproducing a compact disk and a DVD, and to an adjustment process for an optical disk device. Can be. The present invention provides a reference disk by making the thickness of the light transmission layer different in a region where the information recording surface is concentrically divided, and by adjusting an optical pickup and an optical disk device using the reference disk. In addition, the operation of adjusting the optical pickup and the optical disk device is simplified.

[0002]

2. Description of the Related Art Conventionally, in a manufacturing process of an optical pickup, a manufacturing process of a compact disk player, and the like, an optical system is adjusted using a predetermined reference disk.

That is, in an actual compact disk, a disk substrate is prepared by, for example, injection molding a transparent resin, and a reflective film and a protective film are formed on the disk substrate. As a result, the compact disk has birefringence, and unavoidable occurrence of warpage, eccentricity, and the like.

On the other hand, the reference disk is made of a material having no birefringence, such as a disk substrate, and is made of a glass plate that is not easily damaged by the collision of an optical pickup during adjustment. The glass substrate is polished to ensure sufficient accuracy as an adjustment standard.

[0005]

In an optical disk apparatus for reproducing this type of optical disk, it is conceivable to switch the operation of one optical pickup to reproduce a compact disk and a DVD.

However, in the case of a compact disc,
While the thickness of the light transmitting layer is 1.2 mm, the DV
In the case of D, since the thickness of the light transmitting layer is 0.6 [mm], an optical pickup used for reproducing such a compact disc and a DVD has a reference disc for the compact disc and a DVD. It is necessary to make adjustments using a reference disc for each. Therefore, this type of optical pickup has a problem that the adjustment work becomes complicated.

In addition, this kind of reference disk requires time and labor to create, and if a reference disk is prepared for each of a compact disk and a DVD, there is a problem that management and arrangement become complicated accordingly.

Particularly, the DVD has a structure in which a substrate having a thickness of 0.6 mm is bonded, so that a glass substrate having a thickness smaller than that of a compact disk can be processed with high precision even in a reference disk ( 0.6 ± 10 [μ
m] The following accuracy) and lamination are required, which requires time and labor to create.

Further, in this type of reference disk, the pit shape of the stamper is transferred, and the pit shape is formed. Eventually, the work must be done manually, which also requires time and effort to create.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and provides an optical pickup for accessing different types of optical disks, a reference disk capable of simplifying the adjustment work of an optical disk device, an optical pickup adjustment method, and an optical disk. It is intended to propose a method for adjusting the device.

[0011]

According to a first aspect of the present invention, there is provided a first information processing apparatus which is applied to a reference disk and has an information recording surface formed by concentrically dividing an information recording surface.
In the second region, a light transmitting layer is formed with a different thickness, and an information recording surface corresponding to the thickness of the light transmitting layer is formed.

According to the seventh aspect of the present invention, the thickness of the light transmitting layer in the first and second regions formed by concentrically dividing the information recording surface is applied to the method of adjusting the optical pickup. The optical system is adjusted by sequentially seeking the first and second areas with respect to a reference disk formed so as to be different.

According to the ninth aspect of the present invention, the thickness of the light transmitting layer is adjusted in the first and second regions formed by concentrically dividing the information recording surface by applying the method of adjusting the optical disk device. The first and second areas are sequentially sought for a reference disk formed differently from the reference disk to adjust characteristics of a servo system for controlling the optical pickup.

According to the first aspect of the present invention, the light transmitting layer is formed with different thicknesses in the first and second regions formed by dividing the information recording surface into concentric circles by applying to the reference disk. By forming an information recording surface corresponding to the thickness of the light transmitting layer, in an optical pickup and an optical disk device for accessing different types of optical disks, various adjustment operations can be performed using one reference disk. Can be executed, and the adjustment work can be simplified accordingly.

According to the seventh aspect of the present invention, the thickness of the light transmitting layer in the first and second regions formed by concentrically dividing the information recording surface is applied to the method of adjusting the optical pickup. Are different from the reference disk formed differently.
By adjusting the optical system by sequentially seeking the second area, the skew can be adjusted, for example, with a single reference disk even in an optical pickup that accesses optical disks of different types.

According to the ninth aspect of the present invention, the thickness of the light transmitting layer is adjusted in the first and second regions formed by dividing the information recording surface into concentric circles by applying the method for adjusting the optical disk device. Are different from the reference disk formed differently.
By sequentially seeking the second area and adjusting the characteristics of the servo system for controlling the optical pickup, even in an optical disc apparatus accessing different types of optical discs, for example, tracking control, The control target of the focus control can be adjusted.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment (1-1) Configuration of First Embodiment FIG. 1 is a process chart showing a reference disk forming process according to a first embodiment of the present invention. is there. In the process of making the reference disk, the thickness is 0.6, which is the thickness of the light transmitting layer of the DVD.
[Mm], the surface of the glass master 1 whose diameter is the diameter of a DVD is polished and washed, and then fine irregularities 2 are formed on one surface and the outer peripheral area AR1 of the glass master 1 by the so-called 2P method (FIG. 1 (A1)). Here, the fine concave-convex shape 2 forms a pit row serving as various adjustment standards for a DVD reproducing device and a DVD optical pickup.

In the subsequent step, the area AR1 where the fine unevenness 2 is formed is formed.
Then, a reflection film 3 is formed (FIG. 1 (B1)). Here, as shown in FIG. 2, the mask M covers the glass master 1 from the outer peripheral side so that only the area AR1 is exposed.
1 and a mask M2 for covering the inner peripheral side of the glass master 1 are set on the glass master 1 (FIG. 2A), and then Ag, Al or Au is deposited or sputtered on the glass master 1 (FIG. B)), whereby the reflection film 3 is selectively formed in this area AR1 (FIGS. 2 (C1) and (C2)). Note that this area AR1 has an inner diameter d1 = 45 [mm] to an outer diameter d.
2 = 58 [mm].

This manufacturing step (FIG. 1) is different from the processing step of the glass master 1 in that the diameter is the diameter of the compact disk and the thickness is the thickness of the light transmitting layer of the compact disk by injection molding. Disk substrate 4 having a thickness of 0.6 [mm] excluding the thickness of glass master 1
(FIG. 1 (A2)). Here, the disk substrate 4 is formed using a transparent resin such as polycarbonate, for example, and fine irregularities 5 are formed on one surface. Here, this fine uneven shape is used for compact disc playback devices and compact disc optical pickups.
A pit row is formed as a reference for various adjustments.

Subsequently, in this forming step, a reflective film 6 is formed on the surface on which the fine irregularities 5 are formed (FIG. 1 (B1)). Here, this step is performed as shown in FIG.
As in the case of the compact disk, the reflection film 6 is formed except for the inner peripheral side partial area and the outer peripheral side edge.

In this manufacturing step (FIG. 1), the ultraviolet curable resin 7 is dropped on the surface of the disk substrate 4 opposite to the side where the fine unevenness 5 is formed (FIG. 1 (C)). ), The glass master 1 is adhered so that the surface on which the ultraviolet curable resin is dropped is the side on which the uneven shape 2 is formed.
Thereafter, as shown by arrow A, these disk substrates 4
Then, the glass master 1 is rotated integrally to shake off the extra ultraviolet curable resin 7 (FIG. 1 (D)), and the ultraviolet curable resin 7 is cured by irradiating ultraviolet rays to integrate the disk substrate 4 and the glass master 1. (FIG. 1E).

Thus, the production process is performed in the glass master 1
In the area AR1 in which the reflection film 3 is formed on the substrate, the DVD is formed by the fine irregularities 2 of the glass master 1 and the reflection film 3.
And an optical recording layer having a thickness of 0.6 mm is formed on the information recording surface. In the area AR2 on the inner peripheral side, an information recording surface for a compact disk is formed by the fine unevenness 5 of the disk substrate 4 and the reflection film 6, and the glass master 1 and the disk substrate are placed on the information recording surface. A light transmitting layer having a thickness of 1.2 [mm] is obtained by adding the thickness of the light transmitting layer to the thickness of the light transmitting layer.

Thus, in this embodiment, the thickness of the light transmitting layer is made different in the first and second regions AR1 and AR2 where the information recording surface is divided concentrically, and the thickness of the light transmitting layer is further changed. An information recording surface corresponding to each area is created in each of the areas AR1 and AR2, and the compact disc and the D
A reference disk 11 that can be used for adjusting an optical pickup and an optical disk device together with the VD is created.

That is, in the reference disk 11, the area AR1 on the outer peripheral side is allocated to the area for DVD, and a laser beam is irradiated from the glass master 1 side to D.
While it can be used for adjustment of an optical pickup for VD and an optical disk device, the inner area AR2 of this area AR1 is allocated to an area for a compact disk, and similarly a laser is applied from the glass master 1 side. It is designed to be used for adjustment of an optical pickup for a compact disk and an optical disk device by irradiating a beam.

That is, in the manufacturing process of the optical pickup, after setting the optical pickup in a jig on which the reference disk 11 is arranged, if the optical pickup is an optical pickup for a compact disk, the inner area AR2 Then, the optical pickup is sought, and the skew amount and the like are confirmed by observing a reproduced signal waveform or the like. Here, when an abnormality is detected, in the optical pickup manufacturing process, the optical pickup is removed from the jig and the process proceeds to a repairing process.

On the other hand, this optical pickup is a DVD
In the case of the optical pickup, in the manufacturing process of the optical pickup, the optical pickup is sought to the outer peripheral area AR1 to detect a skew amount by observing a reproduced signal waveform or the like. Adjust the tilt of the lens.

On the other hand, this optical pickup is a DVD
In the case of an optical pickup used for reproducing both a DVD and a compact disc, the operation of this optical pickup is switched to an operation of reproducing a DVD, and the optical pickup is sought to an outer peripheral area AR1 to detect a skew amount. The inclination and the like of the objective lens are adjusted so that the skew amount falls within a predetermined standard value. Subsequently, in this manufacturing process, the operation of the optical pickup is switched to the operation of reproducing a compact disk, and the optical pickup is sought to the inner peripheral area AR2 to check the skew amount and the like. Switching between the operation of reproducing a DVD and the operation of reproducing a compact disk is performed by, for example, switching the wavelength of a laser beam applied to the reference disk 11 and returning light obtained by applying the laser beam to the reference disk 11. Is executed by switching the processing of the light reception result.

When the optical pickup holds a skew sensor, the inclination of the skew sensor is adjusted using the reference disk 11. Here, the skew sensor is a sensor that detects the tilt of the optical disk used for reproduction. In an optical disk device that performs control using the skew sensor, the tilt of the optical pickup is corrected based on the detection result of the skew sensor. It is designed to reduce bit errors due to skew.

In the manufacturing process of the optical disk, when manufacturing a compact disk player, the reference disk 11 is loaded in place of the conventional reference disk for the compact disk to access the inner peripheral area AR2, and the compact disk player is accessed. The predetermined adjustment items are adjusted so as to correct various characteristics that change due to the variation in.
That is, by setting the bias of the tracking control and the focus control, which are the adjustments of the characteristics of the servo system for controlling the optical pickup, the control targets of the tracking control and the focus control are adjusted, and the signal level of the reproduction signal is adjusted as necessary. The gain correction amount of the automatic gain control circuit to be corrected is adjusted.

On the other hand, in the case of manufacturing a DVD reproducing apparatus, instead of the conventional DVD reference disk, the reference disk 11 is loaded and the outer peripheral area AR1 is accessed, and the same adjustment items are set. adjust.

On the other hand, a compact disc and a DV
In the case of manufacturing a reproducing apparatus capable of reproducing both D and D, the entire operation is switched between the case of reproducing a compact disk and the case of reproducing a DVD, respectively, to switch the area AR2.
And access to the area AR1 to adjust the bias and the like of the tracking control and the focus control.

(1-2) Operation of the First Embodiment In the above configuration, in the step of creating the reference disk (FIG. 1), the glass master 1 in which the information recording surface for DVD is partially created. Similarly, the first and second regions in which the information recording surface is concentrically divided by bonding and integrating the disk substrate 4 on which the information recording surface for a compact disk is partially formed. In AR1 and AR2, a reference disk 11 in which the thickness of a light transmitting layer corresponds to a DVD and a compact disk, respectively, and an information recording surface corresponding to the thickness of the light transmitting layer is formed in each area AR1 and AR2. Created.

As a result, in the reference disk 11, the area AR1 on the outer peripheral side is allocated to the area for DVD, and the laser beam is irradiated from the glass master 1 to D.
While it can be used for adjusting a VD optical pickup and an optical disk device, the inner peripheral area AR2 of this area AR1 is allocated to the area for a compact disk, and similarly, the glass master 1 By irradiating a laser beam from the side, it can be used for adjustment of an optical pickup for a compact disc and an optical disc apparatus.

In the process of adjusting the optical pickup and the manufacturing process of the optical disk device, only the reference disk 11 is managed and used, and the optical pickup for a compact disk, the optical pickup for a DVD, and the combined use of a compact disk and a DVD are used. The optical pickup can be adjusted, and the management and arrangement of the reference disk can be simplified accordingly.

In the process of making the reference disk,
Since there is no need to create a reference disc for a compact disc and a reference disc for a DVD, management and arrangement can be simplified by that much, and the time required for creation can be reduced.

In particular, with respect to an optical pickup and an optical disk device that are used for both DVDs and compact disks, it is possible to perform one-time adjustment without changing the reference disk.
Since the adjustment operation for the compact disk and the adjustment operation for the DVD can be executed by switching the seek destination by the reference disks, the adjustment operation can be simplified accordingly.

That is, in the adjustment of the optical pickup, the skew which is the inclination of the laser beam with respect to the optical disk due to the inclination of the optical system or the like is adjusted. In the adjustment of the optical disk device, the control of the tracking control and the focus control is performed. It is possible to simplify the work of adjusting the characteristics of various servo systems, which are targets and the like.

As described above, in the reference disk 11 used for various adjustments, the transparent plate-like member constituting the light transmitting layer on the side where the laser beam is incident is made of a glass material. Among the transparent plate-like members constituting the transmission layer, a member made of a material which is hardly damaged is arranged on the outermost side. This prevents the reference disk 11 from being damaged by use.

(1-3) Effects of the First Embodiment According to the above configuration, concentrically divided areas of the information recording surface are set for a compact disc and a DVD, respectively. By making a reference disk with a different thickness of the transmission layer, it is possible to adjust a compact disk, a DVD optical pickup, and an optical disk device with one reference disk, thereby simplifying these adjustment operations. It is also possible to simplify the management of the process and the arrangement of the reference disk.

At this time, a reference disk is prepared by laminating transparent plate members having an information recording surface formed locally, and the transparent plate member on the side where the laser beam is incident is formed of a glass material. Damage to the reference disk can be reduced.

(2) Second Embodiment FIG. 4 is a side view showing a reference disk according to a second embodiment. This reference disk 21 has the same configuration as that of the reference disk 11 according to the first embodiment, except that a part of the shape of the glass master is different, and is similarly prepared. In the configuration shown in FIG. 4, the same components as those of the reference disk 11 described above with reference to FIG. 1 are denoted by the corresponding reference numerals, and redundant description will be omitted.

Here, in the glass master 22, on the side where the information recording surface is not formed, a taper is formed in the peripheral portion 22 A by polishing, whereby the outer peripheral side of the area AR 1 where the information recording surface for DVD is formed is formed. It is formed so that the thickness of the light transmitting layer gradually decreases toward the outer peripheral side.

In the reference disk 21, the operation of the skew servo is confirmed in the step of adjusting the optical pickup and the step of adjusting the optical disk apparatus by using the area where the thickness of the light transmitting layer gradually decreases. The servo circuit can be adjusted.

According to the configuration shown in FIG. 4, the glass substrate is formed such that the thickness of the light transmitting layer is gradually reduced toward the outer peripheral side of the area AR1 where the information recording surface for DVD is formed. In addition to the effect of the first embodiment, the operation of the skew servo can be confirmed and further adjusted by the reference disk 21, thereby further simplifying the adjustment work. Can be.

(3) Third Embodiment FIG. 5 is a process diagram showing a process of creating a reference disk according to a third embodiment. The thickness of the reference disc was 0.1 mm in comparison with the thickness of the light transmitting layer of the DVD.
The surface of the glass master 31 having a thin thickness of 0.5 [mm] and the diameter of a DVD is polished and washed, and then fine irregularities 32 are formed on one side and the outer peripheral area of the glass master 1 by the so-called 2P method. (FIG. 5 (A1)). Here, this fine uneven shape 32 is used for an optical disk having a higher recording density than that of a DVD.
A pit row is formed as a reference for various adjustments of the optical pickup.

Further, in the following step, in a subsequent step, a reflection film 33 is formed in a region where the fine irregularities 32 are formed (FIG. 5 (B1)). The reflection film is formed in the same manner as described in the first embodiment.

The production process is performed by using the glass master 31
In a step separate from the processing step described above, the diameter is the diameter of the compact disc by injection molding, and the thickness is 0.5 [m
m] (FIG. 5 (A2)).
Here, the disk substrate 4 is formed using a transparent resin such as polycarbonate, for example, and fine irregularities 35 and 36 are formed on both surfaces. Here, when these fine irregularities 35 and 36 are superimposed on the glass master 31,
The glass master 31 is formed on the inner peripheral side of the disk substrate 34 so as not to overlap with the region where the irregularities 32 are formed, and further so that the region created between the irregularities 35 and 36 does not overlap. . The uneven shapes 35 and 3
Numeral 6 constitutes a pit array serving as various adjustment standards for DVD and compact disk reproducing devices and their optical pickups.

Subsequently, in this forming step, reflective films 37 and 38 are formed so as to cover the fine irregularities 35 and 36 (FIG. 5B2). Here, the uneven shape 35 for DVD
The reflection film 37 is formed using the same mask as described above with reference to FIG. 2 so that the reflection film is formed only in the region where the uneven shape 35 is formed. The reflection film 38 is formed on the entire surface on the side where the irregularities 36 are formed.

This manufacturing step is followed by the disk substrate 34
After the UV curable resin 7 was dropped on the side where the unevenness 35 for DVD was formed (FIG. 5C), no unevenness of the glass master 31 was formed on the surface where the UV curable resin was dropped. Adhere the side surfaces. Further, after the ultraviolet curable resin 7 is dropped on the surface of the glass master 31 on which the uneven shape is formed, a transparent sheet material 39 having a thickness of 0.1 [mm] is adhered. Then, after the excess ultraviolet curable resin 7 is shaken off, the ultraviolet curable resin 7 is cured by irradiating ultraviolet rays, and the disk substrate 34, the glass master 31, the sheet material 39
(FIG. 1E).

Thus, in this step, various adjustment operations and confirmation operations can be performed with a single reference disk in addition to DVDs and compact disks, as well as higher-density optical disks.

According to the structure shown in FIG. 5, three types of optical disks can also be used as a reference disk, so that management and arrangement can be further simplified, and adjustment work of an optical pickup and an optical disk device can be performed. Can be simplified.

(4) Other Embodiments In the first embodiment, the transparent plate member on the side where the laser beam is incident is made of a glass material. In the second embodiment, a DVD is used. Although the case where the transparent plate-shaped member on the side where the laser beam of the information recording surface for incidence is made of a glass material has been described, the present invention is not limited to this, and instead of these members as necessary, or In addition to the above members, a disk substrate made of plastic, which is another transparent plate member, may be made of a glass material. In this case, if the thickest transparent plate member among these transparent plate members is made of a glass material, the influence of the resin on the birefringence can be reduced as much as the entire reference disk.

On the contrary, if all the transparent plate-like members are made of plastic, a reference disk can be easily made.

In the above-described embodiment, each of the concentrically divided areas is used for a compact disc.
Although the case of allocating to a DVD or the like has been described, the present invention is not limited to this. For example, as shown in FIG. 6, concentrically divided areas are combined, for example, information for a compact disk (for CD) and information for DVD The recording surfaces may be created on the inner circumference side and the outer circumference side of the reference disk.

Further, in the above-described embodiment, the case where the reference disk is formed by laminating the transparent plate members has been described. The transmissive layer and the information recording surface may be concentrically arranged to serve as a reference disk.For example, by forming a reflective film on a disk substrate formed so that the plate thickness changes stepwise in the radial direction, A different kind of reference disk may be created.

Further, in the above-described embodiment, the case has been described where the information recording surface is formed by forming the reflection film in the minute uneven shape for forming the pits and forming the information recording surface. However, the present invention is not limited to this. For example, in place of the minute uneven shape and the reflection film that form the pit, the minute uneven shape and the phase change film or the magnetic film that form the groove are arranged to enable recording and reproduction. An information recording surface may be created. In this way, a reference disk for a recording / reproducing apparatus or the like can be obtained.

[0058]

As described above, according to the present invention, a reference disk is prepared by making the thickness of the light transmitting layer different in a region where the information recording surface is divided concentrically. By adjusting the optical pickup and the optical disk device by using the optical pickup, it is possible to simplify the adjustment work of the optical pickup for accessing different types of optical disks and the optical disk device using the optical pickup.

[Brief description of the drawings]

FIG. 1 is a process diagram showing a process of creating a reference disk according to a first embodiment of the present invention.

FIG. 2 is a process diagram showing a process of forming a reflection film on the glass master disk side in FIG.

FIG. 3 is a plan view for explaining a reflection film of the disk substrate of FIG. 1;

FIG. 4 is a side view showing a reference disk according to a second embodiment of the present invention.

FIG. 5 is a process diagram showing a process of creating a reference disk according to a third embodiment of the present invention.

FIG. 6 is a side view showing a reference disk according to another embodiment of the present invention.

[Explanation of Reference Codes] 1, 22, 31 ... Glass master disk, 2, 5, 32, 35,
36 ... uneven shape, 3, 6, 33, 37, 38 ... reflective film, 4, 34 ... disk substrate, 7 ... ultraviolet curable resin, 11, 21, 41 ... reference disk, 39 ... sheet material

Continued on the front page F-term (reference) 5D118 AA06 BA01 BB01 CA11 CA13 5D119 AA38 BA01 BB01 DA05 EA02 EA03 JC07 5D121 AA02 AA05 AA13 HH19

Claims (10)

[Claims] 1. A light transmission layer having different thicknesses in first and second regions formed by concentrically dividing an information recording surface, and information recording corresponding to the thickness of the light transmission layer. A reference disk having a surface formed. 2. The reference according to claim 1, wherein a transparent plate member on which the information recording surface is locally formed is laminated corresponding to the first and second areas. disk. 3. The reference disk according to claim 2, wherein the transparent plate-like member on the side where the laser beam is incident is made of a glass material. 4. The reference disk according to claim 2, wherein the thickest transparent plate-like member is made of a glass material. 5. The reference disk according to claim 1, wherein the information recording surface is formed by forming a reflective film on a fine unevenness of the light transmitting layer. 6. The thickness of the light transmitting layer in the first region is 0.6 mm, and the thickness of the light transmitting layer in the second region is 1.2 mm.
2. The reference disk according to claim 1, wherein the reference disk is [mm]. 7. A reference disk formed so that the thickness of a light transmitting layer is different between first and second regions formed by concentrically dividing an information recording surface, wherein the first and second regions are formed. 2. A method for adjusting an optical pickup, wherein the optical system is adjusted by sequentially seeking the area No. 2. 8. The method according to claim 7, wherein the adjustment of the optical system is a skew adjustment. 9. A first and second reference discs having different thicknesses of a light transmitting layer in first and second areas formed by dividing an information recording surface into concentric circles. 2. An adjustment method for an optical disk device, wherein a servo system for controlling an optical pickup is adjusted by sequentially seeking the area No. 2. 10. The method according to claim 9, wherein the adjustment of the servo system is an adjustment relating to a control target of tracking control and / or focus control.