JPH0528542A - Stamper inspection device for optical device - Google Patents

Abstract

PURPOSE:To provide a stamper inspection device for an optical disk which can accurately measure the factors of the depth and the width, etc., of a sector mark pit or the channel shape, etc., of a stamper, which affects the fluctuation of the signal level of a sector mark. CONSTITUTION:This device has an optical pickup head(PUH)7 provided with two signal detection system having a light source of different two wavelengths and a similar detection organization to accurately measure the factor of the depth and the width of the sector mark pit or the channel shape which affects the fluctuation at the time of measuring the signal level of the sector mark of the stamper 6. As the light source and the detection organization of the different two wavelengths in one PUH 7, the difference of the size of a sector mark signal owing to the difference of the wavelengths can simultaneously measured so that it becomes possible to accurately measure the factor of the depth(dp) and width(dw),etc., of the sector mark pit. Thus, the inspection accuracy of the stamper can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk stamper inspection device for inspecting various characteristics and defects of an optical disk stamper.

[0002]

2. Description of the Related Art Optical disc manufacturing processes can be roughly divided into a mastering process (master disc manufacturing process) and a replication process (duplicating process). The mastering process is a process for producing a stamper, and the replication process uses the stamper. This is a process of manufacturing an optical disc by injection molding. Therefore, the quality of the stamper manufactured in the mastering process has a great influence on the quality of the disc, so that it is important to inspect various characteristics such as optical characteristics, defects, and signal modulation degree of the stamper.

Therefore, conventionally, an optical disk stamper inspection apparatus for inspecting various characteristics of the stamper has been developed (for example, "optical disk stamper inspection apparatus", Toshiba Review, Vol. 44, No. 5, P420 to P422 (1989)). The optical pickup head of the conventional optical disk stamper inspection device (hereinafter,
For PUH, a product equivalent to an ordinary optical pickup head for recording / reproducing is used, and the PUH is composed of a sensor unit and a sensor drive unit. As shown in FIG. 17, the sensor unit is composed of a semiconductor laser light source, an optical system, a four-division photodiode that detects reflected light from the stamper, and the like. The sensor driving unit is a control unit such as a drive unit. It is composed of a drive coil system for driving the sensor unit in the vertical (focus) and the horizontal (tracking) directions according to the signal.

[0004]

By the way, the conventional optical disk stamper inspection apparatus has only one type of light source wavelength and has only one PUH system. Track cross signal,
Push-pull signal and header (sector mark)
The amplitude modulation degree (hereinafter referred to as a sector mark signal) and the like are measured, and other defect inspections are performed to evaluate the optical disc in accordance with the ISO standard. On the other hand, here, the sector mark signal (| I _sm | / I ₀ ;
Considering I ₀ : reflected light intensity of the mirror portion, and _Ism : reflected light intensity of the sector mark portion, the intensity is the depth (d of the pit 35 of the sector mark portion of the stamper 34 shown in FIG. 3 (d
p) and width (wp), the depth, width, and pitch of the groove 36, the light source wavelength of the PUH, the state of the spot 37, and the like.

Therefore, a case where the condition of the groove portion 36 is made constant will be considered here. For example, set the width of the groove 36 to 0.
5 μm, depth 0.175 × λ / n (λ: light source wavelength, n refractive index), spot diameter 1.6 μm (1 / e ² ),
Calculate the relationship between pit depth and sector mark signal strength when the sector pit width is 0.3 μm, 0.5 μm, and 0.7 μm. The graph of FIG. 4 shows the calculation result.
Looking at this graph, for example, when the depth (dp) of the pit 35 in units of λ / n hits the peaks and valleys of the characteristic curve in the vicinity of 0.3 and 0.5, the sector mark signal changes in response to changes in the depth (dp). (|
There is not much change in I _sm | / I ₀ ). On the contrary, the depth (dp) is 0.
In the vicinity of 4, the change of the sector mark signal (| I _sm | / I ₀ ) appears remarkably with respect to the change of the depth (dp).

[0006] In optical discs, those of the same standard are usually the same pit depth (dp) and pit width (wp), and the conditions are the optical disc substrate (polycarbonate (PC)).
Etc.) is determined to be optimum. Here, with the optical disk stamper 34, the pit depth d
If p = 260 nm and PUH wavelength λ is 830 nm (n =
1), and the depth of the pit in units of λ / n is 260/830 = 0.
31. As described above, in the vicinity of dp = 0.31 (× λ / n), even if dp varies, the sector mark signal (| I _sm | / I
₀ ) does not change much. However, assuming that the light source wavelength λ of PUH is 670 nm, the pit depth in units of λ / n is 260/670 = 0.39, and here, the variation of dp is due to the sector mark signal (| I _sm | / I ₀ ). Will be reflected in the fluctuation of. Therefore, when the sector mark signal (| I _sm | / I ₀ ) is detected by using the light sources of two different wavelengths in this way, the depth (dp) and the width (wp) of the sector mark pit can be accurately obtained. I understand that it will be done. However, since the conventional optical disk stamper inspection device is equipped with only one system of PUH having only one light source wavelength, the factors such as the depth and width of the sector mark pit that affect the fluctuation of the signal level of the sector mark are accurately determined. Could not be measured.
Therefore, it is a first object of the present invention to provide an optical disk stamper inspection apparatus capable of accurately measuring factors such as the depth and width of sector mark pits that affect the fluctuation of the signal level of the sector mark.

By the way, when reproducing an optical disk substrate as a product, the laser beam emitted from the PUH and focused is an optical disk substrate (polycarbonate (PC)).
Alternatively, the grooves (or pits) are irradiated through polymethyl methacrylate (PMMA) or the like. On the other hand, in the optical disc stamper, the laser beam emitted from the PUH and focused is directly (through the air) irradiated. Therefore, the optical depth of the groove (or pit) varies depending on the difference in the refractive index thereof. Therefore, the signals (levels) obtained from the optical disk stamper and the optical disk substrate are different. However, if there is a correlation between each signal (level) obtained from the stamper and the optical disk substrate, if each signal (level) of the stamper is measured, it is possible to judge the pass / fail and to evaluate the stamper. However, in reality, it is difficult to correlate the signal (level) obtained from the stamper and the optical disk substrate. Therefore, simply measuring the signal (level) of the stamper does not mean that the stamper is evaluated. Therefore, in the present invention, in order to evaluate the optical disk stamper, each factor of the groove shape (sector mark pit depth: Dp, sector mark pit width: Wp, groove depth: Dg, groove width: Wg, from the signal (level) is used. The second object is to provide an optical disk stamper inspection device capable of accurately measuring

[0008]

In order to achieve the first object, the stamper inspection apparatus for an optical disk according to claim 1 has a sector mark which influences the fluctuation of the signal level of the sector mark of the stamper. In order to accurately measure the factors of the depth and width of the pit, the optical pickup head is equipped with two signal detection systems having light sources of different two wavelengths and a similar detection mechanism. . Further, the optical disk stamper inspection apparatus according to claim 2 has the same mechanism for accurately measuring the factors of the depth and width of the sector mark pits that affect the variations when measuring the signal level of the sector mark of the stamper. It has two optical pickup heads provided with light sources having different wavelengths.

In order to achieve the second object, the optical disk stamper inspection device according to the third aspect of the invention has a groove shape (sector mark pit depth: Dp, sector mark pit width: Wp, groove depth: Dg, groove width:
In order to measure Wg), it is characterized by having an optical pickup head provided with light sources of two different wavelengths and two signal detection systems having a similar detection mechanism. Further, the optical disk stamper inspection device according to claim 3 is
Two optical pickups with the same mechanism and light sources with different wavelengths for measuring the groove shape (sector mark pit depth: Dp, sector mark pit width: Wp, groove depth: Dg, groove width: Wg) It is characterized by having a head.

[0010]

The optical pickup head (PUH) of the optical disk stamper inspection apparatus according to claim 1 of the present invention is different in that
Sector mark signals (| I _sm | / I ₀ ) of the stamper at the light source wavelengths of wavelengths (eg, λ ₁ = 830 nm, λ ₂ = 670 nm)
Therefore, the width (wp) of the sector mark pit is calculated from the λ ₁ signal, and the depth is calculated from the λ ₂ signal.
By the procedure of obtaining (dp), the factors such as the depth (dp) and the width (wp) of the sector mark pit can be accurately measured. Further, in this case, the same position of the stamper can be measured at the same time. Further, the optical disk stamper inspection apparatus according to the second aspect is an example in which two PUHs having different light source wavelengths are provided in order to prevent the structure of the PUH from becoming complicated and making assembly and adjustment difficult. When two PUHs with different light source wavelengths are provided in this way, it is possible to measure 180 ° opposite positions at the same time. Further, both of the optical disk stamper inspection apparatuses according to claims 1 and 2 are capable of measuring once at each wavelength in two steps, and the depth (dp) and width ( The factor of wp) can be measured more accurately.

Next, in order to achieve the second object, in the invention described in claim 3, the PUH is provided with light sources of two different wavelengths and two signal detection systems having a similar detection mechanism.
In addition, in the invention described in claim 4, two PUHs each having a light source of a different wavelength are used. Here, how is actually obtained each factor of the groove shape? Will be explained. First, Wp and Wg are obtained. The symbols used in the description are as follows: I ₀ : intensity of reflected light from the mirror portion, I ₁ : intensity of reflected light on one side of the track (groove), I ₂ : intensity of reflected light on the other side of the track (groove). , I _sm: reflected light intensity on the sector mark, wg, wp: shows the groove, a pit portion groove width of the respective factors, respectively, also, d
g and dp are standardized groove depths of the groove and pit portions, respectively, and are multiplied by a coefficient (λ (wavelength) / n (refractive index)) to obtain actual optical groove depths. Also, Wg, Wp, Dg, Dp
Is the actual (specific) value of the optical disk stamper (n = 1
In).

12, FIG. 13 and FIG. 14, FIG. 12 shows the relationship between wg, dg and the push-pull (tracking error) signal strength on the groove (track). Therefore, the tracking error signal of the stamper is measured at the wavelengths of λ ₁ and λ ₂ by the device of the present invention. The data at λ ₁ is Tr1 and the data at λ ₂ is Tr2. Where dg in FIG. 12 is λ ₁ ,
Consider the actual relationship of Dg by multiplying each by λ ₂ (n = 1). As an example, wg = 0.7, λ ₁ = 830 nm, λ ₂ = 67
The graph of FIG. 13 shows the relationship at 0 nm. That is, such a relationship is required for each wg, but from the relationship and the data of Tr1 and Tr2, W
Calculate g and Wg. For example, if Wg = 0.7 μm, then in FIG. 13, Tr1 and Tr2 are on the same Dg value on the curves of λ ₁ and λ _2, respectively. Similar relations are established even when Wg has different values, and therefore Wg and Dg satisfying the above relation can be obtained from Tr1 and Tr2. However, there are cases where the relationship between Tr1 and Tr2 is the same in two places (in the example of FIG. 13, λ ₁
And occurs near the intersection of the λ ₂ curves). In such a case, the value of Dg (or Wg) cannot be determined, so at this time, the on-track signal (R
Fg (RFg1, RFg2)) is measured. FIG. 14 shows the relationship between the on-track signal (RFg) and wg and dg. Applying RFg1 and RFg2 to this relationship, W
The values of g and Dg can be determined.

Next, Wp and Dp are obtained. At this time, Wg and Dg have already been obtained (the track pitch has already been obtained by another method), and the push-pull signal strength (Trp) on the sector mark pit and wp and dp for them have been obtained.
Relationship (FIG. 15) and the sector mark signal strength (R
There is a relation between F) and wp, dp (previous FIG. 4), and it is obtained from these. First, Trp1 and Trp2 at wavelengths λ ₁ and λ ₂ are measured by the apparatus of the present invention, and Wp and Dp are obtained from FIG. 15. At this time as well, λ ₁ , λ ₂ from FIG. Is multiplied by dp and Dp is plotted on the horizontal axis, the conversion is performed. As an example, wp = 0.5 μm, λ ₁ = 830
FIG. 16 shows the case where nm and λ ₂ = 670 nm. Also at this time,
If Wp = 0.5 .mu.m, Trp1 and Trp2 will be on the same Dp value on the curve of each wavelength. Although Wp and Dp are obtained by this, two solutions may be obtained at this time as well, so at this time, RF at λ ₁ and λ ₂
1 and RF2 are measured and fitted to the relationship of FIG. 4, Wp, Dp
To decide. From the above, Wg, Dg, Wp, and Dp are obtained, and the groove shape of the stamper is found. These cannot be obtained by the optical disk stamper inspection device equipped with only the PUH of the light source of one wavelength as in the conventional example. Note that the relationships in FIGS. 12, 14, 15, and 4 are obtained by simulation, and the contents thereof are described in the literature (“Optimal design of pregroove and prepit shape in push-pull tracking servo system”, Shimizu,
(Optical Memory Symposium '90)).

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a schematic configuration diagram showing an embodiment of an optical disk stamper inspection apparatus according to claim 1, and FIG. 2 is a schematic configuration diagram showing an embodiment of the optical pickup head (PUH). Further, FIG. 3 is a detailed view of the shapes of spots and pits in the sector mark portion of the stamper as viewed from A of FIG. Also, as described above, FIG. 4 shows the depth (dp) of the sector mark pit and the sector mark signal (| I _sm |
/ I ₀ ), the graph of FIG. 5 is a schematic diagram showing an embodiment of the optical disk stamper inspection device according to claim 2, and FIG. 6 is an embodiment of the optical pickup head (PUH). It is a schematic block diagram.

First, an embodiment of the optical disk stamper inspection apparatus according to claim 1 will be described. In the optical disk stamper inspection apparatus having the configuration shown in FIG. 1, reference numeral 1 is a surface plate, 2 is a motor, 3 is a spindle, 4 is a vacuum hole for stamper chucking, 5 is a turntable, 6 is an optical disk stamper to be inspected, and 7 is Optical pickup head (PU
H), 8 is a slider for moving in the Z-axis direction, 9 is a slider for moving in the X-axis direction, 10 is an X-axis direction feed motor, 11 is an output terminal for RF signal, focus error signal, tracking error signal, and 12 is a focus servo unit. , 13 is a tracking servo unit, 14 is a Z-axis feed controller, 15 is an X-axis feed controller, 16 is a rotation control system for the turntable rotation motor 2, and 17 is a system controller including a control personal computer or the like. .

Next, an outline of the PUH 7 will be described with reference to FIG. In FIG. 2, reference numerals 18 and 19 denote semiconductor lasers (LD), which are semiconductor lasers 18 as examples.
Is a semiconductor laser with a wavelength of λ ₁ = 830 nm.
Emits a laser beam having a wavelength λ ₂ = 670 nm and is arranged as shown in the figure. In FIG. 2, reference numerals 20 and 21 are collimator lenses, 22 and 23 are polarization beam splitters (PBS) for laser light of wavelength λ ₁ and
1/4 wave plate, 24 and 25 are PBS and 1/4 wave plate in the laser beam of wavelength λ ₂ , and 26 is a dichroic cube mirror which transmits the laser beam of wavelength λ ₁ and reflects the laser beam of wavelength λ ₂ . Reference numeral 33 is an objective lens (NA =
0.5), 34 is the surface of the stamper to be inspected. Also, the code 2
Reference numerals 7 and 28 are condenser lenses, 29 and 29 'are knife edges with a reflection mirror, 30a and 31a are tracking split pin photodiodes, and 30b and 31b are tracking split pin photodiodes 30a and 31a, respectively. FIG. 3 is a plan view showing a spot state. Also, 32 and 32 'are for focus 2
It is a split pin photodiode. P having the configuration shown in FIG.
In the UH, the RF signal is taken out as the sum of the output voltages of the tracking two-divided pin photodiode 30a and the focusing two-divided pin photodiode 32 for the laser light of wavelength λ ₁ , and for the laser light of wavelength λ _2. That is, it is extracted as the sum of the output voltages of the tracking two-divided pin photodiode 31a and the focusing two-divided pin photodiode 32 '.

Next, FIG. 3 is a sectional shape of the sector mark pit portion of the stamper 6 as seen from the direction of arrow A in FIG. 2 as described above. Reference numeral 35 is a sector mark pit portion, 36 is a groove portion, and a sector mark. Pit width and depth wp, d
It is defined as p. Further, FIG. 4 shows that when the groove width is 0.5 μm, the depth is 0.175 × λ / n (λ: light source wavelength, n refractive index), and the spot diameter is 1.6 μm, the sector pit width wp is 0.3 μm. , 0.5 μm, 0.7 μm, pit depth dp and sector mark signal strength (| I _sm | /
It is a graph which calculated the relationship of _I0 ). As already described with reference to FIGS. 3 and 4 in the above-mentioned problem section, the sector mark signal (| I _sm | /
I ₀ ), the sector mark pit depth (d
p) and width (wp) can be accurately obtained, but the PUH7 of the optical disk stamper inspection device having the configuration shown in FIGS.
Then, two different wavelengths (eg, λ ₁ = 830 nm, λ ₂ = 670)
nm) light source and two signal detection systems having a similar detection mechanism, the sector mark signal (| I _sm | / I ₀ ) of the stamper can be simultaneously measured with laser lights of two different wavelengths. it can. Therefore, seeking sector mark pit width (wp) from lambda ₁ of the signal, the depth from the lambda ₂ signal of
By the procedure of obtaining (dp), the factors such as the depth (dp) and the width (wp) of the sector mark pit can be accurately measured. In this case, the same position of the stamper 6 can be measured at the same time.

Next, an embodiment of the optical disk stamper inspection device according to the second aspect will be described. The optical disk stamper inspection device having the configuration shown in FIG. 5 includes two PUHs 44 and 45 having the same mechanism and light sources having different wavelengths. The light source wavelength of each PUH 44 and 45 is, for example, λ ₁ = 830 nm, It is set such that λ ₂ = 670 nm.
Further, the PUHs 44 and 45 have the same configuration, and are configured as shown in FIG. 6, for example. In FIG. 5, reference numerals
38: surface plate, 39: motor, 40: spindle, 41: vacuum hole for stamper chucking, 42: turntable, 43
Is an optical disk stamper to be inspected, 46 and 47 are sliders for moving in the Z-axis direction, 48 and 49 are sliders for moving in the X-axis direction, and 50 and 51.
Is an X-axis feed motor, 57 'and 58' are RF signal, focus error signal, and tracking error signal output terminals, 5
Reference numerals 7 and 58 are a focus servo unit and a tracking servo unit, 53 and 54 are Z-axis direction feed controllers, 55 and 56 are X-axis direction feed controllers, 52 is a rotation control system of a turntable rotation motor 39, and 59 is a control unit. A system controller including a personal computer or the like. Further, in FIG. 6, reference numeral 60 is an LD for emitting a laser beam having a wavelength λ ₁ or λ ₂ , 61 is a collimator lens, 62 is a PBS, 63 is a ¼ wavelength plate, 64 is an objective lens, and 65 is a stamper to be inspected. 66
Is a condenser lens, 67 is a knife edge with a reflection mirror, 68 is a 2-pin pin photodiode for focusing, 69a is a 2-pin pin photodiode for tracking, and 69b is a light-receiving surface and a spot state of the 2-pin pin photodiode for tracking 69a. It is a top view shown.

In the optical disk stamper inspection device having the structure shown in FIG. 5, the structure of the PUH 7 having the structure shown in FIG.
Two PUH44s with the same mechanism and light sources with different wavelengths,
This is an example in which 45 is provided, and 2 provided with different light sources in this way
If two PUHs 44 and 45 are provided, the sector mark signal (| I _sm | / I ₀ ) of the stamper can be measured at the same time by laser beams of two different wavelengths, as in the device shown in FIGS. . Therefore, the depth (dp) and width of the sector mark pit can be calculated by the procedure of obtaining the width (wp) of the sector mark pit from the signal of λ _{1 and} the depth (dp) from the signal of λ _2.
The factor of (wp) can be accurately measured. Further, when two PUHs 44 and 45 having different light source wavelengths are provided in this way, the sliders 48 and 49 for moving the PUH 44 and the PUH 45 in the X-axis direction can be operated in synchronism, and the stamper 43 can be operated in the same groove. It is possible to track the position opposite 180 °.

Next, FIG. 7 is a schematic configuration diagram showing an embodiment of an optical disk stamper inspection device according to claim 3, and FIG. 8 is a schematic configuration diagram showing an embodiment of the optical pickup head (PUH). . FIG. 9 is a schematic enlarged sectional view of the sector mark pits and grooves, in which the focused spot of the sector mark portion of the optical disk stamper is irradiated, as viewed from A in FIG. 10 is a schematic configuration diagram showing an embodiment of the optical disk stamper inspection device according to claim 4, and FIG. 11 is a schematic configuration diagram showing an embodiment of the optical pickup head (PUH). First, claim 3 of FIG.
An embodiment of the described optical disk stamper inspection device will be described. In FIG. 7, reference numeral 101 is a surface plate, 102 is a motor, 103 is a spindle, 104 is an air exhaust hole for stamper vacuum chucking, 105 is a turntable, 106 is an optical disc stamper to be inspected, and 107 is an optical pickup head (PU).
H), 108 is a PUH vertical feed mechanism, 109 is a PUH horizontal feed mechanism, 110 is a horizontal feed motor, 111 is an output terminal for RF signal, focus error signal and tracking error signal, 112 is a focus servo section, 113 is Tracking servo unit, 114 vertical feed control system, 115 horizontal feed control system, 116 turntable rotation motor 102
Is a rotation control system, and 117 is a system controller including a control computer and the like.

Next, an outline of the PUH 107 will be described with reference to FIG. In FIG. 8, reference numerals 118 and 119 are semiconductor lasers (LD) having wavelengths λ ₁ and λ ₂ , 120 and 121 are collimator lenses (CL), 122 and 123 are polarization beam splitters (PBS), and 124 and 125 are 1/4 wave plate, 1
A dichroic cube mirror 26 transmits a laser beam having a wavelength λ ₁ and reflects a laser beam having a wavelength λ ₂ . Reference numeral 127 is an objective lens, 128 and 129 are condenser lenses, and 13
0 and 131 are knife edges, half of the light flux is reflected, and 132 and 1
It is incident on the two-division photodetector 33. Reference numerals 137 and 138 are plan views showing the dividing direction of the light receiving surface and the spot state. Reference numerals 134 and 135 are two-division photo detectors for focus error detection.

Here, FIG. 9 is a schematic enlarged sectional view of the stamper 106 near the focal position of the objective lens as seen from the direction of arrow A in FIG. In FIG. 9, 139 is the ray of the beam, 140
Is the sector mark pit and 141 is the groove (track)
Is. In each of the signals described above, I ₀ and I _sm are wavelengths λ ₁
Is the sum of the outputs of the 132 and 134 two-divided photodetectors, and I ₁ and I ₂ are the respective outputs of the 137 divided pieces. Similarly, in the case of the wavelength λ ₂ , I ₀ and I _sm are 133 and 13 respectively.
5 is the sum of the outputs of the two-division photo detector, and I ₁
And I ₂ are the respective outputs of each of the 138 pieces. As already explained in the above section of action, two different wavelengths λ
_If I ₁ , I ₂ , I ₀ , and _Ism are detected using the light sources of ₁ and λ ₂ , the groove shape of the optical disk stamper of FIG. 9, that is, the actual depth Dp and width Wp of the sector mark pit 140, The actual depth Dg and width Wg of the groove 139 can be accurately determined. Further, in the PUH107 of the optical disk stamper inspection device having the configuration shown in FIGS. 7 and 8, two different wavelengths λ ₁ and λ _{2 are used.}
It is possible to measure the same place of the stamper at the same time by using the laser light of two different wavelengths, since it is equipped with the above light source and two signal detection systems having a similar detection mechanism.

Next, an embodiment of the optical disk stamper inspection apparatus according to claim 4 will be described. The optical disk stamper inspection device having the configuration shown in FIG. 10 includes two PUHs 147 and 148 having the same mechanism and light sources having different wavelengths, and each PUH 147 and 148 has the same configuration. It is configured as shown in. Figure 10
Reference numeral 155 is a surface plate, 142 is a motor, 143 is a spindle, 144 is an air exhaust hole for stamper vacuum chucking, 145 is a turntable, 146 is an optical disc stamper to be inspected, 147 and 148 are optical pickup heads (PUH), 14
9, 150 is a PUH vertical feed mechanism, 151, 152 is a PUH horizontal feed mechanism, 153, 154 are horizontal feed motors, 157, 158
Are output terminals for RF signal, focus error signal, tracking error signal, 159 and 160 are focus servo units, 16
1 and 162 are tracking servo units, 163 and 164 are vertical feed control systems, 165 and 166 are horizontal feed control systems, 156 is a turntable rotation motor 142 rotation control system, and 167 is a control computer. It is a system controller. Further, in FIG. 11, reference numeral 168 is a semiconductor laser (LD) having a wavelength λ ₁ or λ ₂ , 169 is a collimator lens (CL), 170 is a polarization beam splitter (PBS),
171 is a quarter wavelength plate, 172 is an objective lens, 173 is a condenser lens, 174 is a knife edge, and half of the light flux is reflected 175
It is incident on the two-division photo detector. 177 is part 2
It is a top view which shows the division | segmentation direction and the spot state of the light-receiving surface of a division | segmentation photodetector. Further, reference numeral 176 is a two-division photo detector for detecting a focus error.

In the optical disk stamper inspecting apparatus having the configuration shown in FIG. 10, the PUH107 having the configuration shown in FIG. Two PUHs with different light sources
This is an example in which 147 and 148 are provided. If two PUHs 147 and 148 provided with different light sources are provided in this manner, similar to the device shown in FIGS. I ₁ , I ₂ , I ₀ , _Ism can be detected, and the groove shape of the stamper for the optical disk of FIG. 9, that is,
The depth Dp and width Wp of the sector mark pit 140 and the depth Dg and width Wg of the groove 139 can be accurately obtained. That is, when two PUHs 147 and 148 having different light source wavelengths are provided in this way, it becomes possible to operate the horizontal feed mechanisms 151 and 152 of the PUH 147 and PUH 148 in synchronization.
PUH on the same track of optical disk stamper 146
The signals at λ ₁ and λ ₂ are measured so that the positions facing each other by 180 ° are tracked, data processing is performed by the system controller unit 167, and the groove shape of the optical disk stamper is calculated and obtained.

[0025]

As described above, in the optical disk stamper inspection device according to the first aspect, the light source and the detection optical system of two different wavelengths are provided in one PUH.
The difference in the size of the sector mark signal due to the difference in wavelength can be measured at the same time, which makes it possible to accurately measure the factors such as the depth (dp) and width (wp) of the sector mark pit. The inspection accuracy can be improved. Further, the optical disk stamper inspection device according to claim 2 has the same effect as that of the optical disk stamper inspection device according to claim 1, and further, PUH
Since it is divided into two parts, there is an advantage that each PUH optical system can be implemented with a simple configuration. Further, in the optical disk stamper inspection device according to claim 3, by providing the light source and the detection optical system of two different wavelengths in one PUH,
The groove shape of the stamper for an optical disk can be obtained from each signal of each wavelength. Further, the optical disk stamper inspection device according to claim 4 has the same effect as that of the optical disk stamper inspection device according to claim 3, and since the PUH is divided into two, each PUH is
The optical system of 1 has an advantage that it can be implemented with a simple configuration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an optical disk stamper inspection device according to claim 1.

FIG. 2 is an optical pickup head (PU of the apparatus shown in FIG.
It is a schematic block diagram which shows one Example of H).

FIG. 3 is a detailed view of the shapes of spots and pits in the sector mark portion of the stamper as viewed from A of FIG.

FIG. 4 is a graph showing a relationship between a depth (dp) of a sector mark pit and a sector mark signal (| I _sm | / I ₀ ).

FIG. 5 is a schematic configuration diagram showing an embodiment of an optical disk stamper inspection device according to claim 2;

6 is an optical pickup head (PU of the apparatus shown in FIG.
It is a schematic block diagram which shows one Example of H).

FIG. 7 is a schematic configuration diagram showing an embodiment of an optical disk stamper inspection device according to claim 3;

FIG. 8 is an optical pickup head (PU of the apparatus shown in FIG.
It is a schematic block diagram which shows one Example of H).

9 is an enlarged schematic cross-sectional view of the stamper in the vicinity of the focal position of the objective lens as viewed in the direction of arrow A in FIG.

FIG. 10 is a schematic configuration diagram showing an embodiment of an optical disk stamper inspection device according to claim 4;

11 is a schematic configuration diagram showing an embodiment of an optical pickup head (PUH) of the apparatus shown in FIG.

FIG. 12 is a graph showing the relationship between the groove depth and width factors dg and wg and the push-pull (tracking error) signal strength on the groove (track).

FIG. 13: Actual groove depth Dg and groove (track) when Wg = 0.7 μm, λ ₁ = 830 nm, λ ₂ = 670 nm
It is a graph which shows the relationship of the above push pull (tracking error) signal strength.

FIG. 14 is a graph showing a relationship between groove depth and width factors dg and wg and an on-track signal.

FIG. 15: Factor d of depth and width of sector mark pit
It is a graph which shows the relationship between p and wp and the push pull signal strength on a sector mark pit.

FIG. 16 is a graph showing the relationship between the actual depth Dp of the sector mark pit and the push-pull signal strength on the sector mark pit when Wp = 0.5 μm, λ ₁ = 830 nm, and λ ₂ = 670 nm.

FIG. 17 is an explanatory diagram of an optical pickup head of a conventional optical disc stamper inspection device.

[Explanation of symbols]

6,34,43,65,106,146 ... Stamper 7,44,45,107,147,148 ... Optical pickup head
(PUH) 18, 19, 60, 118, 119, 168 ・ Semiconductor laser light source 35, 140 ・ ・ ・ ・ Sector mark pits 36, 141 ・ ・ ・ ・ Grooves dp ・ ・ ・ ・ Sector mark pits Depth wp ・ ・ ・ Sector mark pit width dg ・ ・ ・ Groove depth wg ・ ・ ・ Groove width Dp ・ ・ ・ Actual sector mark pit depth Wp ・ ・ ・ Actual sector Width of mark pit Dg ... Depth of actual groove Wg ... Depth of actual groove

Claims (4)

[Claims] 1. An optical disc stamper inspection device for inspecting optical characteristics and defects of an optical disc stamper, wherein factors such as the depth and width of sector mark pits that affect variations in the signal level of sector marks of the stamper are measured. In order to accurately measure the above, an optical disk stamper inspection device having an optical pickup head provided with two signal detection systems having different wavelength light sources and a similar detection mechanism. 2. An optical disc stamper inspection device for inspecting optical characteristics and defects of an optical disc stamper, wherein factors such as depth and width of sector mark pits that affect fluctuations in the signal level of sector marks of the stamper are measured. In order to accurately measure the optical disc stamper inspection device, the optical disc stamper inspection device has two optical pickup heads having the same mechanism and light sources having different wavelengths. 3. An optical disk stamper inspection device for inspecting optical characteristics and defects of an optical disk stamper, the groove shape (sector mark pit depth: Dp, sector mark pit width: Wp, groove depth: Dg, groove). An optical disk stamper inspection device having an optical pickup head equipped with two signal detection systems having different two wavelength light sources and a similar detection mechanism for measuring the width (Wg). . 4. An optical disk stamper inspection device for inspecting optical characteristics and defects of an optical disk stamper, the groove shape (sector mark pit depth: Dp, sector mark pit width: Wp, groove depth: Dg, groove). An optical disk stamper inspection device having two optical pickup heads having light sources of different wavelengths with the same mechanism for measuring width (Wg).