JP2790648B2 - How to make dual grating - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a dual grating for forming gratings on both sides of a substrate.

2. Description of the Related Art Conventionally, as a method of forming a grating on the surface of an optical information recording medium such as an optical disk, for example, Japanese Patent Application Laid-Open No.
There is one disclosed in Japanese Patent Publication No. 116105. A method for producing this by a well-known ultraviolet curing method (2P method) using an optical disk as an example will be described with reference to FIGS. 8 to 10.

First, a stamper (die) 3 is fixed on a support plate 2 placed under the U-shaped arm 1, and an ultraviolet curable resin 4 is poured into the surface of the stamper 3. On the other hand,
The acrylic plate 7 is vacuum-chucked at the peripheral end of the holder 6 fixed to the upper cylinder 5, and air is introduced between the holder 6 and the acrylic plate 7 to make the acrylic plate 7 convex. Then, as shown in FIG. 9, the acrylic plate 7 is lowered in this state, pressed from above the ultraviolet curable resin 4 to bring the acrylic plate 7 into close contact with the stamper 3, and then the holder 6 is detached. Then, in a state where the acrylic plate 7 and the stamper 3 are brought into close contact with each other, as shown in FIG. 10, the acrylic plate 7 is exposed to ultraviolet (UV) light and cured, and then the stamper 3 is peeled off. As a result, a desired optical disk having the grating replicated on the surface of the acrylic plate 7 can be produced.

Problems to be Solved by the Invention In the case of the above-described apparatus, a grating can be easily formed on one side of an acrylic plate 7 (hereinafter, referred to as a substrate) by an ultraviolet curing method. In a dual grating that creates gratings on both sides, consider the case where this is applied to a signal detection unit for an optical pickup of a magneto-optical disk. The transmitted light generated by making light incident on the created dual grating is considered. Since the light receiving element is arranged at the position where the two lights of the light and the diffracted light arrive and the signal is detected by this, if the shape of the substrate is misaligned with the grating direction formed on the substrate, If the grating directions formed on both sides are shifted, the accuracy of the signal detection will be significantly reduced. Become.

In order to match the directions of the gratings formed on the front and back surfaces of the dual grating, Japanese Patent Application No. 1-53209 has filed a method for producing a dual type grating by the present applicant.
This will now be described with reference to FIGS. 11 and 12. A substrate 9 having a front surface grating 8 formed on one surface in advance is brought into close contact with an upper portion of a back surface stamper 11 having a back surface grating 10 formed thereon via an ultraviolet curable resin 12, and in this state,
A laser beam emitted from a laser light source 14 movably in a horizontal direction H or a vertical direction V attached to an upper portion of a support 13 is made incident on the upper surface of the substrate 9. And then
All of the light (reflected light, diffracted light) reflected by the front surface grating 8 and the back surface grating 10 is reflected on a straight line 16 drawn on a locus plane 15 disposed above. To reach. Thus, the position of the grating direction to be duplicated on both the front and back surfaces of the substrate 9 is adjusted to create a dual grating.

However, in this case, as shown in FIG. 12, the surface grating 8 has been duplicated on the substrate 9 in advance. For this reason, as shown in FIG. 13, if the shape of the substrate 9 and the direction of the surface grating 8 (groove direction) are duplicated in a shifted state, as described above in this state, When a dual grating is prepared by such a method, the direction of the front surface grating 8 and the direction of the back surface grating 10 that are duplicated on both the front and back surfaces of the substrate 9 are deviated. As a result, when the thus-developed dual grating is used as an optical separation means for detecting a signal for an optical pickup, a reduction in diffraction efficiency and a light demultiplexing rate is caused, and accurate signal detection cannot be performed. .
For this reason, it is necessary to adjust the shape of the substrate 9 and the direction of the surface grating 8 at the stage of duplicating the surface grating 8 on one side of the substrate 9.

Means for Solving the Problems According to the invention as set forth in claim 1, a stamper is mounted on a rotary stage, and the surface grating is placed at a symmetrical position on a straight line passing through the center of a circle of the stamper, and the groove direction thereof is aligned with the straight line. It is formed so as to be parallel or linear, and the laser beam emitted from the laser light source is incident on the surface grating, and the reflected light is reflected on a straight line drawn on a trajectory surface disposed above the stamper. Fine adjustment is performed by rotating only the stamper so as to reach the surface grating, and then, an ultraviolet curable resin on the surface grating is applied, and the substrate is closely contacted in a state where the substrate is oriented in a predetermined direction by the substrate positioning means. The surface grating was duplicated on the substrate side by performing ultraviolet exposure.

According to a second aspect of the present invention, a stamper is placed on a rotary stage, and the grating for the back surface is positioned at a symmetrical position on a straight line passing through the center of the stamper so that its groove direction is parallel to or perpendicular to the straight line. The stamper is formed such that a laser beam emitted from a laser light source is incident on the back surface grating and the reflected light reaches a straight line drawn on a trajectory surface disposed above the stamper. Rotate only to make fine adjustments, and then apply an ultraviolet curable resin on the back surface grating and adhere the back surface side of the duplicated substrate of the front surface grating, and then again by the laser light source from above the substrate. The laser beam is incident, and the light reflected by the grating for the front surface and the grating for the back surface all reaches the straight line drawn on the track surface. After the substrate was subjected to fine adjustment by rotating as was to replicate the back surface grating on the back side of the substrate with ultraviolet exposure.

According to the first aspect of the present invention, a laser beam is made incident on the surface grating formed on the surface stamper, and the reflected light reaches a straight line on the track surface. In this state, the substrate is positioned by the substrate positioning means. By determining the direction and bringing the surface grating into close contact, the surface grating can be duplicated on the surface of the substrate with the shape of the substrate and the direction of the surface grating matched.

According to the second aspect of the present invention, a laser beam is made incident on the back surface grating formed on the back surface stamper so that the reflection term reaches a straight line on the trajectory surface. By causing the laser beam to be incident again and causing the reflected light to reach a straight line on the track surface, the directions of the gratings formed on both the front and back surfaces of the dual grating can be made in a state where there is no deviation.

Embodiment First, an embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. The stamper 17 has a cylindrical shape and is arranged on a rotating stage (not shown).
On a plurality of straight lines 18 passing through the center A of the stamper 17, surface gratings 19 are formed symmetrically from the center A. Further, a stamper holder 20 is provided around the stamper 17, and a cover 21 serving as a substrate positioning means, which is located above the stamper 17, is detachably attached to one end of the stamper holder 20. . One end B of the cover 21 coincides with the direction of the straight line 18 of the stamper 17, and a concave portion 22 is formed at a position facing a part of the surface grating 19.

The laser beam 23 is attached via a laser holder 24 to a support plate 25 provided with a vertical rotation stage (not shown) that rotates in a plane in the vertical direction V. It is fixed to a support 27 via a horizontal rotating stage 26 that rotates inside.

In such a configuration, a method of duplicating the surface grating 19 on one side of the substrate 28 will be sequentially described below. First, the stamper 17 is arranged on the rotating stage. Next, a surface grating 19 is formed at a symmetrical position on a straight line 18 passing through the center A of the stamper 17 so that its groove direction is parallel to or perpendicular to the straight line 18. Next, the laser light source
When the laser beam emitted from 23 is made incident on the surface grating 19 on the stamper 17, the light reflected by the laser beam is divided into two lights of reflected light and diffracted reflected light. At this time, fine adjustment is performed by rotating only the stamper 17 using the rotating stage so that the reflected light and the diffracted reflected light reach the straight line 30 drawn on the trajectory surface 29 provided above. Next, after performing this adjustment, an ultraviolet curable resin 31 is applied on the surface grating 19, and the cover 21 is attached while slightly floating from the surface of the stamper 17. Since the cover 21 is located in the portion where the surface grating 19 is present and the recess 22 is formed, the substrate 28 is positioned in the recess 22 and is brought into close contact with the ultraviolet curable resin 31, and then the ultraviolet light is irradiated. By performing the exposure, the surface grating 19 can be duplicated on the substrate 28 side. Also, when duplicating the surface grating 19 formed in the plurality of other sectors 32 of the stamper 17, the duplication can be performed by the same means as the above-described production method.

As described above, by using the straight line 30 drawn on the trajectory surface 29, adjustment is performed so that the reflected light and the diffracted reflected light all reach the straight line 30, and the substrate 28 is moved along the recess 22 of the cover 21.
The gap between the shape of the substrate 28 and the direction of the surface grating 19 in the past.
Can be eliminated.

Next, an embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG. This is because, in the embodiment of the first aspect of the present invention, the surface grating is provided on one side.
The back surface grating 33 is duplicated on the opposite surface by using the 19 duplicated substrates 28, thereby creating a dual grating. Hereinafter, the method will be described step by step.

First, the stamper 17 is set on the rotating stage. A grating 33 for the back surface is formed at a symmetrical position on the straight line 18 passing through the center A of the stamper 17 so that its groove direction is parallel to or perpendicular to the straight line 18, and is emitted from the laser light source 23 to the grating 33 for the back surface. Incident laser beam. Thus, fine adjustment is performed by rotating only the stamper 17 so that the reflected light and the diffracted reflected light reach the straight line 30 drawn on the track surface 29 disposed above the stamper 17. The above-described method can be performed in the same manner as in the above-described embodiment of the first aspect of the present invention.

Next, after this adjustment, an ultraviolet curable resin 31 is applied on the back surface grating 33, and the back surface side of the copied substrate 28 of the front surface grating 19 is brought into close contact. A laser beam is incident. At this time, the incident light first passes through the front surface grating 19, is then reflected by the back surface grating 33, and passes through the front surface grating 19 again, so that the transmitted light (reflected light) and the diffracted light (diffraction Light) and 2 × 2 ×
It is split into 2 = 8 light beams. At this time, so that all eight lights reach the straight line 30 drawn on the trajectory surface 29,
The substrate 28 is rotated to perform fine adjustment. Next, a dual grating in which the front surface grating 19 and the back surface grating 33 are formed on both the front and back surfaces of the substrate 28 by performing ultraviolet exposure to duplicate the back surface grating 33 on the back surface side of the substrate 28 (see FIG. 7). ) Can be created.

As described above, using the straight line 30 drawn on the trajectory surface 29, the laser beam is made incident on the grating 33 for the back surface, adjustment is performed, and then the grating 19 for the front surface is overlaid on the grating 33 for the back surface again. By making the laser beam incident and adjusting so that all eight light beams reflected by these two gratings reach the straight line 30, the direction between the front surface grating 19 and the back surface grating 33 can be adjusted. A dual grating can be created in a state where "shift" does not occur.

According to the first aspect of the present invention, a laser beam is made incident on a surface grating formed on a surface stamper, and the reflected light reaches a straight line on a trajectory plane. Since the mounting direction of the substrate is determined and adhered, the surface grating can be duplicated on the surface of the substrate in the state where the shape of the substrate and the direction of the surface grating are matched without shifting as in the past, In addition, since the alignment in the grating direction can be performed simply by using a straight line drawn on the track surface, the adjustment operation can be easily performed.

According to the second aspect of the present invention, after the back surface grating formed on the back surface stamper is adjusted by the same means as the front surface grating, the substrate on which the front surface grating is duplicated is superposed in this state. Since the laser beam was incident again and all the reflected light reached the straight line on the trajectory plane, the adjustment was made.
A dual grating can be created in a state where the front-side grating and the back-side grating are completely matched without causing a direction shift, whereby the dual grating can be used as an optical separation means for detecting a signal for an optical pickup. However, the signal detection can be performed accurately even when the method is used.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the invention described in claim 1,
FIG. 2 is a plan view showing a state where a surface grating is formed on a stamper, FIG. 3 is a side view showing a state where a cover is attached to the stamper, FIG. 4 is a plan view thereof, and FIG. FIG. 6 is a side view showing a state in which the front surface grating is duplicated on the substrate side, FIG. 6 is a side view showing a state in which the rear surface grating is duplicated on the substrate side according to an embodiment of the present invention, and FIG. Is a side view showing a state of a dual grating in which gratings are duplicated on both the front and back surfaces of the substrate, FIGS. 8 to 10 are process diagrams showing a conventional one-sided grating preparation process, and FIG. 11 is a prior application filed by the present applicant. FIG. 12 is a side view showing a state in which a dual grating is produced by using the conventional example, and FIG. 13 is a view showing a shift generated between the direction of the surface grating and the shape of the substrate. Is a plan view showing the state. 17 Stamper, 18 Linear, 19 Grating for surface, 21 Substrate positioning means, 23 Laser light source, 28
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──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 7/26 G11B 7/135 G02B 5/18 B29D 17/00

Claims (2)

(57) [Claims] 1. A stamper is mounted on a rotary stage, and a surface grating is formed at a symmetrical position on a straight line passing through the center of the stamper so that its groove direction is parallel or perpendicular to said straight line. Rotating only the stamper so that a laser beam emitted from a laser light source is incident on the surface grating and the reflected light reaches a straight line drawn on a trajectory surface disposed above the stamper. Then, a fine adjustment is performed, and then, an ultraviolet curable resin is applied on the surface grating, and the substrate is brought into close contact with the substrate in a state where the substrate is oriented in a certain predetermined direction by a substrate positioning means, thereby performing the ultraviolet exposure. The method for producing a dual grating, wherein the surface grating is duplicated. 2. A stamper is mounted on a rotary stage, and a grating for a back surface is formed at a symmetrical position on a straight line passing through the center of the stamper so that its groove direction is parallel to or perpendicular to the straight line. Rotating only the stamper so that a laser beam emitted from a laser light source is incident on the back surface grating and the reflected light reaches a straight line drawn on a trajectory surface disposed above the stamper. After performing fine adjustment, after applying an ultraviolet curable resin on the back surface grating and bringing the back surface side of the copied substrate of the front surface grating into close contact, the laser light source is again irradiated from above the substrate by the laser light source. The light incident on and reflected by the grating for the front surface and the grating for the back surface is set so as to reach all the straight lines drawn on the track surface. After fine adjustment by rotating the substrate,
A method for producing a dual grating, wherein the grating for the back surface is duplicated on the back surface side of the substrate by ultraviolet exposure.