JPH05242506A - Optical disk device - Google Patents

Abstract

PURPOSE:To obtain a device easy for adjusting and at a low cost by arranging masks provided with a pin hole respectively on the prescribed positions of light paths divided in a focus error detection method by a spot size method. CONSTITUTION:The mask provided with the pin hole 39 and the senser 40 are disposed between a beam splitter 34 and an image forming point 37 Further the mask provided with the pin hole 41 and the senser 42 are disposed backward than the image forming point 38 to the splitter 34. Thus, the transmission luminous flux of image forming beams 35 and 36 are limited by the pin holes 39, 41 respectively and the limited luminous flux are converted to electric signals by the sensers 40, 42 and inputted to an operational amplifier 45 and outputted as a focus error signal. Thus, a focus error is detected by finding the difference between light quantity passing through the pin holes 39, 41 and multi-divided senser is unnecessitated. Thus, the positional adjustment between the senser and the reflection beam is facilitated and a manufacturing cost is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device.

[0002]

2. Description of the Related Art In recent years, optical disk devices have come to be used for recording information in computers and the like.

A conventional focus error detection method using the spot size method (SSD method) of an optical disk device will be described below.

FIG. 13 is a block diagram of a focus error detector of a conventional optical disk device. In FIG. 13, 1 is a semiconductor laser that outputs laser light 2, 3 is a collimator that converts the laser light 2 output from the semiconductor laser 1 into parallel light 4, and 5 is a beam splitter, which is the parallel light converted by the collimator 3. The light from the objective lens 6 is reflected by the light passing through the lens 4. Reference numeral 7 is an optical disk board, 8 is a spot imaged on the optical disk board 7 by the objective lens 6, 9 is a light beam reflected by the optical disk board 7 and further reflected by the beam splitter 5, and 10 is a light beam 9 into an image forming light 11. An image forming lens for conversion, 24 is a beam splitter for splitting the image forming light 11 into two image forming lights 12, 13, 14 is an image forming point of the image forming light 12, 1
Reference numeral 5 denotes an image forming point of the image forming light 13. Reference numerals 16 and 17 denote sensors for detecting light. The sensor 16 is arranged in front of the image forming point 14 (on the side of the image forming lens 10).
5 is arranged on the rear side. Reference numeral 23 denotes a pickup base member, on which various optical parts such as the semiconductor laser 1, collimator 3, beam splitter 5, objective lens 6, imaging lens 10 and beam splitter 24 are positioned and fixed.

The operation of the optical disk device configured as described above will be described. In FIG. 13, a laser beam 2 emitted from a semiconductor laser 1 is converted into a parallel beam 4 by a collimator 3. After passing through the beam splitter 5, the parallel light 4 is passed through the objective lens 6 and then the optical disc board 7
An image is formed as a spot 8 on. The reflected light from the optical disk board 7 is reflected by the beam splitter 5 and becomes a light beam 9. An image forming lens 10 converts the light ray 9 into an image forming light 11. A beam splitter 24 divides the image forming light 11 into two image forming lights 12 and 13. The image forming point of the image forming light 12 is 14, and the image forming point of the other image forming light 13 is 1.
It is 5. The image forming light 12 and the image forming light 13 are converted into electric signals by the sensors 16 and 17, respectively. This sensor 16 is in front of the imaging point 14 (on the imaging lens 10 side)
And the sensor 17 is placed behind the imaging point 15. Here, details of the sensor 16 and the sensor 17 are shown in FIG. The sensor 16 has three parts 16a, 16
The sensor 17 is also divided into three parts 17a, 17b and 17c. When the relationship between the objective lens 6 and the optical disc board 7 is in the in-focus position, the spot shapes on the sensors 16 and 17 are
It has the shape shown in FIGS. In this state, the sensors 16a, 16b, 16c, 17a, 17
The signals of b and 17c are I (16a), I (16b), I
(16c), I (17a), I (17b), I (17
c), the sensors 16a, 16b, 16c, 17 are provided so that the relationship shown in the following (Equation 1) is established.
The shapes of a, 17b, and 17c are determined.

[0006]

[Equation 1]

When the relationship between the objective lens 6 and the optical disk board 7 is at the in-focus position, the differential output of the operational amplifier 22 is as shown in the following (Equation 2).

[0008]

[Equation 2]

Next, when the distance between the optical disc board 7 and the objective lens 6 becomes small and the relationship between the objective lens 6 and the optical disc board 7 deviates from the focused state, the spot shapes on the sensors 16 and 17 are 18a and 19a. And signal I (16
a), I (16b), I (16c), I (17a), I
The relationship between (17b) and I (17c) is as shown in (Equation 3) below.

[0010]

[Equation 3]

When the relationship between the objective lens 6 and the optical disc board 7 deviates from the in-focus position, the differential output of the operational amplifier 22 becomes as shown in the following (Equation 4).

[0012]

[Equation 4]

On the contrary, when the distance between the optical disk 7 and the objective lens 6 becomes large and the relationship between the objective lens 6 and the optical disk 7 deviates from the focused state, the spot shapes on the sensors 16 and 17 are 18b and 19b. And signal I (16
a), I (16b), I (16c), I (17a), I
The relationship between (17b) and I (17c) is as shown in (Equation 5) below.

[0014]

[Equation 5]

When the relationship between the objective lens 6 and the optical disk board 7 deviates from the in-focus position, the differential output of the operational amplifier 22 becomes as shown in the following (Equation 6).

[0016]

[Equation 6]

As described above, the direction of deviation from the focus can be detected by the positive and negative electric signals of the output of the operational amplifier 22.

Considering the assembling process of such a structure, first, the optical parts such as the semiconductor laser 1, the collimator 3, the beam splitter 5, the objective lens 6, the image forming lens 10 and the beam splitter 24 are included in the pickup base member 23. The positioning is adjusted and then the sensors 16, 17
Position adjustment is performed. This adjustment is very delicate in that the semiconductor laser 1 is driven to adjust the positional relationship between the sensors 16 and 17 and the reflected light from the optical disk board 7 or an alternative reflecting board. The position of the sensor is adjusted by the surfaces 23a and 23b of the pickup base member 23.
14 and mainly in the Z direction which is the dividing direction of the sensors 16 and 17 in FIG.

[0019]

However, in the above-mentioned conventional configuration, the positional relationship between the spots 18 and 19 and the sensors 16 and 17 (especially in the Z direction) in the in-focus state is expressed by (Equation 1).
It is necessary to make fine adjustments on the order of several microns or less so that the relational expression of is satisfied, and this adjustment time is generally long, which is several minutes, which hinders cost reduction. Further, this adjusted positional relationship must be kept stable for a long period of time even after production, and there is a problem in that durability is lacking.

[0020]

In order to solve the above problems, the present invention solves the above-mentioned problems by optical means for converging the reflected light from the optical disk board, dividing means for dividing the light from the optical means, and dividing means by the dividing means. A pinhole for transmitting a part of the light, which is arranged before the focus in the state where the focus on the optical disk board is best in the optical path through which the reflected light passes
Of the mask and the first mask split by the splitting means, and the light different from the light passing through the pinhole is disposed behind the focus on the optical disc in the optical path through which different light passes. Second mask having a pinhole for transmitting a part of the generated light, first detecting means for detecting the amount of light passing through the pinhole of the first mask, and pin of the second mask A second detection unit that detects the amount of light that has passed through the hole is provided, and focus control is performed based on the difference between the amount of light detected by the first detection unit and the amount of light detected by the second detection unit. It was composed.

[0021]

With the above structure, the present invention detects the light amount of the reflected light from the optical disc through the pinholes of the first mask and the second mask by the first detecting means and the second detecting means, respectively. The focus error can be detected by taking the difference in the amount of light that has passed through the pinholes of the first mask and the second mask.

[0022]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a focus error detection unit of an optical disk device according to a first embodiment of the present invention. In FIG. 1, 43 is a semiconductor laser that outputs laser light 59, 25 is a collimator that converts the laser light 59 output from the semiconductor laser 43 into parallel light 26, and 27.
Is a beam splitter, which transmits the parallel light 26 converted by the collimator 25 and reflects the light from the objective lens 28. 29 is an optical disk board, 30 is a spot imaged on the optical disk board 29 by the objective lens 28, 31 is reflected by the optical disk board 29, and the beam splitter 27
, 32 is an image forming lens for converting the light beam 31 into image forming light 33, and 34 is the image forming light 33,
5 and 36 are beam splitters, and 37 is the imaging light 3
An image forming point of 5 and an image forming point of the image forming light 36. Reference numeral 39 is a pinhole arranged between the beam splitter 34 and the image forming point 37, and 40 is a sensor having a sufficiently large detection area as compared with the luminous flux transmitted through the pinhole 39. Reference numeral 41 is a pinhole arranged behind the image forming point 38 with respect to the beam splitter 34, and 42 is a sensor having a sufficiently large detection area as compared with the light flux transmitted through the pinhole 41. These sensors 40 and 42 need not be specially divided sensors. Four
A pickup base member 4 includes a semiconductor laser 43, a collimator 25, a beam splitter 27, and an objective lens 2.
Optical components such as 8, the imaging lens 32, the beam splitter 34, the pinhole 39, and the pinhole 41 are positioned and fixed. Reference numeral 45 is an operational amplifier that inputs the signals from the sensors 40 and 42 through a resistor 46 and outputs the difference between the signals, 47 is a variable resistor that changes the magnitude of the signal input to the operational amplifier 45, and 70 is the output from the operational amplifier 45. Is a focus control unit for performing focus control.

The operation of the optical disk device configured as described above will be described. In FIG. 1, the laser light 59 emitted from the semiconductor laser 43 is converted into parallel light 26 by the collimator 25. After passing through the beam splitter 27, the parallel light 26 is imaged as a spot 30 on the optical disc board 29 by the objective lens 28. The reflected light from the optical disc board 29 becomes a light beam 31 by the beam splitter 27. Reference numeral 32 denotes an imaging lens, which is a ray 3
1 is converted into image forming light 33. Reference numeral 34 is a beam splitter that splits the image forming light 33 into two image forming lights 35 and 36.
The image forming point of the image forming light 35 is 37, and the image forming point of the other image forming light 36 is 38. Beam splitter 34 and image forming point 3
A pinhole 39 and a sensor 40 having a detection area that is sufficiently larger than the luminous flux that passes through the pinhole 39 are disposed between the pinhole 39 and the sensor 7. In addition, the beam splitter 34
On the other hand, a pinhole 41 and a sensor 42 having a detection area that is sufficiently larger than the luminous flux that passes through the pinhole 41 are provided behind the image formation point 38. Imaging light 3
5 and the imaging light 36 have their transmitted luminous fluxes limited by the pinhole 39 and the pinhole 41, respectively, and the limited luminous fluxes are converted into electric signals by the sensors 40 and 42 and input to the operational amplifier 45 via the resistor 46. It is output from the operational amplifier 45 as a focus error signal.
The focus control unit 70 controls the distance between the objective lens 28 and the optical disc board 29 based on this focus error signal.

Next, the assembly adjustment process in the first embodiment of the present invention will be described. First, the semiconductor laser 43, the collimator 25, the beam splitter 27, the objective lens 28,
Imaging lens 32, beam splitter 34, pinhole 3
Optical parts such as 9, 41 are positioned and fixed to the pickup base member 44. After that, the sensor 40,
42 are attached to the attachment surfaces 44a and 44b of the pickup base member 44, respectively. Since the detection areas of the sensors 40 and 42 are sufficiently large for position adjustment at this time, it is sufficient that the transmitted light fluxes from the pinholes 39 and 41 are included in the detection areas of the sensors 40 and 42, which is extremely delicate. No adjustment is necessary. Sensors 40, 42
The electric signals from the operational amplifier 45 are respectively transmitted through the resistor 46.
, And one input terminal of the operational amplifier 45 is grounded via a variable resistor 47.

Next, the semiconductor laser 43 is driven, and the reflected light from the optical disk board 29 is monitored as an electrical signal of the sensor 40 or 42, and the state where the signal waveform becomes clear is the relationship between the objective lens 28 and the optical disk board 29. Is in focus, the variable resistor 47 is adjusted so that the focus error signal becomes 0, that is, the output of the operational amplifier 45 becomes 0 at this time.

Next, the principle of detecting the focus error by the pinholes 39 and 41 will be described with reference to FIGS. 2 to 9 show the relationship between the pinholes 39 and 41 and the image forming lights 35 and 36, respectively.

First, FIG. 2 is a view showing a state at the time of focusing. In FIG. 2, reference numeral 48 denotes an image forming optical element, which has a function of a convex lens in which the objective lens 28 and the image forming lens 32 shown in FIG. 1 are combined. The light beam 49 directed to the spot 30 is reflected by the optical disc board 29 to become a light beam 50, which is incident on the imaging optical element 48 and becomes the imaging lights 35 and 36 which are focused on the imaging points 37 and 38. Here, pin holes 39, 4
The transmitted lights 51 and 52 from 1 are adjusted to have the same light amount in the focused state. How the light amounts of the transmitted lights 51 and 52 adjusted in this way change when the focus state deviates from the state in which the optical disc board 29 approaches the image forming optical element 48, moves away from the state in which the focus state is reached. The process will be described with reference to FIGS. 3 to 9, and the sensor 4 at that time will be described.
FIG. 10 shows changes in output signals from 0 and 42.

First, FIG. 3 is a diagram showing a relationship between the pinholes 39 and 41 and the image forming points 37 and 38 in a state where the optical disc board 29 is greatly approached from the focus position 53 to the image forming optical element 48 side. Light flux 49 emitted from the imaging optical element 48
Should originally be focused on the spot 30, but since the optical disc board 29 is close to the imaging optical element 48 side, the light flux 49 is reflected at the reflection point 54 and enters the imaging optical element 48, An image is formed at the image forming points 37, 38 farther from the image forming points 37, 38 at the time of focusing in FIG. In this state, the pinholes 39 and 41 are both located between the imaging optical element 48 and the imaging points 37 and 38. The optical disk board 29 in the state of FIG.
When moving away from 8 (approaching the in-focus position 53), the imaging light 3
5 and 36, since the area that passes through the pinholes 39 and 41 is relatively larger than the area that is blocked by the pinholes 39 and 41, the amount of transmitted light 51 and 52 from the pinholes 39 and 41 is increased. However, the increasing tendency of the transmitted light 52 continues to the state of FIG. 4, and the increasing tendency of the transmitted light 51 continues to the state of FIG. 7.

FIG. 4 shows a state where the optical disk board 29 approaches the focus position 53 from the state of FIG. 3 and all the light flux of the image forming light 36 just passes through the pinhole 41. From this state to the state of FIG. 5, the transmitted light 52 from the pinhole 41
Of the transmitted light 51 from the pinhole 39 continues to increase. Even in this state, the positions of the pinholes 39 and 41 are between the image forming optical element 48 and the image forming points 37 and 38 after the state of FIG.

In FIG. 5, the optical disk 29 is closer to the in-focus position 53 than in the state of FIG. 4, the image forming point 38 is between the image forming optical element 48 and the pinhole 41, and the image forming light 36 is formed. This shows a state in which all the light fluxes have just passed through the pinhole 41. From the state of FIG. 4 to the state of FIG. 5, the light amount of the transmitted light 52 from the pinhole 41 hardly changes. However, when the image forming point 38 further moves to the image forming optical element side 48 from the state of FIG. 5, the amount of transmitted light 52 starts to decrease. On the other hand, the position of the pinhole 39 is at the imaging optical element 48.
And the image formation point 37, the amount of transmitted light 51 from the pinhole 39 continues to increase.

FIG. 6 is the same as FIG. 2 and shows the case where the optical disc board 29 is in the in-focus position. The amounts of transmitted light 51, 52 from the pinholes 39, 41 are equal.

FIG. 7 shows the optical disc board 29 beyond the focusing position 53 and away from the imaging optical element 48, and the pinhole 39 is located between the imaging optical element 48 and the imaging point 37. At the same time, all of the light flux of the image forming light 35 just passes through the pinhole 39. From the state of FIG. 6 to the state of FIG. 7, transmitted light 51 from the pinhole 39
The amount of light increases. On the other hand, the image forming point 38 is formed by the image forming optical element 4.
8 and the pinhole 41, the amount of transmitted light 52 from the pinhole 41 decreases.

FIG. 8 shows the optical disc board 29 further away from the image forming optical element 48 than the state shown in FIG. 7, and the image forming point 37 is between the image forming optical element 48 and the pinhole 39, and the connection is made. This shows a state in which all of the luminous flux of the image light 35 has just passed through the pinhole 39. 7 to 8, the light amount of the transmitted light 51 is the vignetting caused by the light flux 50 protruding from the effective diameter of the imaging optical element 48.
There is almost no change except that the light amount of 5 itself slightly decreases. On the other hand, the image forming point 38 is between the image forming optical element 48 and the pinhole 41, and the amount of the transmitted light 52 from the pinhole 41 continues to decrease.

FIG. 9 shows the optical disk board 29 further away from the image forming optical element 48 than the state shown in FIG. 8, and the image forming points 37 and 38 are the image forming optical element 48 and the pinholes 39 and 41.
, And the amount of transmitted light 51, 52 decreases from the state of FIG. 8 to the state of FIG. This tendency continues if the optical disk board 29 is further away from the imaging optical element 48.

FIG. 10 shows changes in the transmitted light amounts 51 and 52 from FIG. 3 to FIG. 9 described above. Figure 1
0 (a) is the signal waveform of the sensor 42, FIG. 10 (b) is the signal waveform of the sensor 40, and FIG. 10 (c) is the signal waveform output from the operational amplifier 45 which is the difference signal between the sensor 42 and the sensor 40. 10 (a), 10 (b), and 10 (c), the signal change from FIG. 3 to FIG. 4 is the region (I), and the signal change from FIG. 4 to FIG. 5 is the region (I).
I), the signal changes from FIG. 5 to FIG. 7 are region (III),
The signal change from FIG. 7 to FIG. 8 is the region (IV), and the signal change from FIG. 8 to FIG. 9 is the region (V). What is used as the actual focus error detection is the straight section of the region (III). The gradient of the straight line in the region (III) may be optimally set by factors such as the numerical aperture of the imaging optical element 48, the positions of the pinholes 39 and 41, and the diameter.

As described above, the direction of deviation from the focus and the magnitude of the deviation are represented by the output of the operational amplifier 45,
It is output as a focus error signal.

(Embodiment 2) FIG. 11 is a block diagram of a focus error detecting portion of an optical disk device according to a second embodiment of the present invention, in which a pinhole 56 is printed on one end surface 55a of a beam splitter 55, a light-shielding film is deposited, etc. And the other end surface 5
The pinhole 57 is formed in 5b by the same method.

(Embodiment 3) FIG. 12 is a block diagram of a focus error detector of an optical disk device according to a third embodiment of the present invention. In the first embodiment of FIG. 1 and the second embodiment of FIG. Although the two sensors 40 and 42 are separately arranged, in the third embodiment of FIG. 12, the sensors 58a and 58b are arranged on one sensor base 58. On the upper surface of the rectangular parallelepiped glass member 60, two split image-forming lights 6 are formed.
A hologram 63 for generating 1 and 62 is formed, and a light shielding film 64 having two pinholes 64a and 64b is formed on the lower surface. In this case, two sensors 58
a and 58b need only detect the amount of light transmitted from the two pinholes 64a and 64b.
If the detection area of 58b is sufficiently larger than the luminous flux transmitted from the pinholes 64a and 64b, the position adjustment of the sensor is unnecessary. The hologram 63 is composed of two hologram areas having different image forming positions and different image forming distances. The image forming position of the image forming light 61 generated by the first region is 65 in the glass member 60, and the other image forming light 62 is formed.
The image forming position of is at 66 outside the glass member 60.

[0039]

According to the present invention, the optical means for converging the reflected light from the optical disc, the dividing means for dividing the light from the optical means, and the optical disc on the optical path through which the light divided by the dividing means passes. A first mask provided with a pinhole for transmitting a part of the light, which is arranged before the focus in the best focus state, and a pinhole of the first mask divided by the dividing means. A second mask having a pinhole for transmitting a part of the light arranged behind the focus in the best focus state on the optical disk board in the optical path through which light different from the transmitted light passes A first detecting means for detecting the amount of light passing through the pinhole of the first mask, and a second detecting means for detecting the amount of light passing through the pinhole of the second mask. Has and is detected by the first detection means The construction further performs focus control by the difference of the light amount and detected by the light amount and the second detecting means, the amount of reflected light from the optical disc board, first
Through the pinholes of the second mask and the second mask, and the first detecting means and the second detecting means respectively detect the difference, and obtain the difference in the amount of light that has passed through the first mask and the second mask pinholes. Since the focus error can be detected by this, the multi-division sensor is not required, the position adjustment between the sensor and the reflected light is easy, and it is less affected by dimensional changes due to aging, temperature change, etc. The cost can also be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a focus error detection unit of an optical disc device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a pinhole and an image formation point when focusing is performed on the optical disk device according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a pinhole and an image formation point in a state where the optical disk disc of the optical disc device according to the first embodiment of the present invention is much closer to the imaging optical element side than the focus position.

FIG. 4 is an explanatory view showing a state in which the optical disc board of the optical disc apparatus in the first embodiment of the present invention approaches the in-focus position from the state of FIG. 3, and all of the light flux of the imaging light just passes through the pinhole.

FIG. 5 is a view showing that the optical disk board of the optical disk device in the first embodiment of the present invention is closer to the in-focus position from the state of FIG. 4, and one image forming point is between the image forming optical element and the pinhole. Along with this, an explanatory view showing a state in which all of the luminous flux of the image forming light just passes through the pinhole.

FIG. 6 is an explanatory diagram showing a state in which the optical disc of the optical disc device according to the first embodiment of the present invention is in a focused position.

FIG. 7 is a view showing a state where the optical disc of the optical disc device in the first embodiment of the present invention is beyond the focusing position and away from the image forming optical element, and the position of one pinhole is the image forming optical element and the image forming point. And an explanatory view showing a state in which all of the luminous flux of the image-forming light just passes through the pinhole and

8 is a diagram illustrating a state where the optical disc of the optical disc device according to the first embodiment of the present invention is further away from the image forming optical element than the state of FIG. 7, and one image forming point is formed by the image forming optical element and the pinhole. Explanatory drawing showing a state in which all of the light flux of the image-forming light just passes through the pinhole while being in between

FIG. 9 is an explanatory diagram showing a state in which the optical disc board of the optical disc device in the first embodiment of the present invention is further away from the imaging optical element than the state of FIG.

FIG. 10 is a waveform diagram of a focus error signal of the optical disk device according to the first embodiment of the present invention.

FIG. 11 is a configuration diagram of a focus error detection unit of an optical disc device according to a second embodiment of the present invention.

FIG. 12 is a configuration diagram of a focus error detection unit of an optical disc device according to a third embodiment of the present invention.

FIG. 13 is a configuration diagram of a focus error detection unit of a conventional optical disc device.

FIG. 14 is an enlarged view of a sensor of a focus error detection unit of a conventional optical disc device.

[Explanation of symbols]

 25 Collimator 27 Beam Splitter 28 Objective Lens 29 Optical Disc Board 32 Imaging Lens 34 Beam Splitter 39 Pinhole 40 Sensor 41 Pinhole 42 Sensor 43 Semiconductor Laser 63 Hologram

Claims (4)

[Claims] 1. A condensing means for condensing light from a light source onto an optical disk board to be mounted, an optical means for condensing reflected light from the optical disk board, and a dividing means for dividing the light from the optical means. A first hole provided with a pinhole for transmitting a part of the light arranged before the focus on the optical disk board in the best focus state in the optical path through which the light divided by the dividing means passes The mask and the light that passes through the pinhole of the first mask divided by the dividing means are arranged behind the focus in the best focus state on the optical disc in the optical path through which different light passes. A second mask provided with a pinhole for transmitting a part of the provided light; first detecting means for detecting the amount of light having passed through the pinhole of the first mask; and the second mask. Come through the pinhole in the mask From the output means, second detection means for detecting the light quantity of light, output means for outputting the difference between the light quantity detected by the first detection means and the light quantity detected by the second detection means, and the output means An optical disc device comprising: 2. The optical disk device according to claim 1, wherein the first mask and the second mask are formed integrally with the dividing means. 3. The optical disk device according to claim 1, wherein the optical means and the dividing means are integrally formed by a hologram. 4. The optical means and the dividing means are integrally formed by a hologram and provided on one end face of a glass member, and the first mask and the second mask are provided on the other end face of the glass member. The optical disk device according to claim 1, wherein the optical disk device is provided.