JP2986737B2 - Optical component bonding method and optical pickup device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which a surface subjected to fine processing such as a diffraction grating and another optical component surface are bonded stepwise with a reaction-curable adhesive, and the adhesive strength and the optical strength are improved. The present invention relates to an optical component bonding method and an optical pickup device for ensuring characteristics.

[0002]

2. Description of the Related Art Conventionally, bonding between a flat surface, such as a diffraction grating, and a flat surface of a part of an optical component has been performed to prevent the adhesive from penetrating into the fine processing portion. Adhesion is performed on the side surfaces, not on the surfaces in contact with each other. For example, as shown in FIG. 6, an adhesive having a high viscosity is dropped on a side surface of the optical component A and the optical component B, that is, so-called overlay bonding is performed. That is,
This high-viscosity adhesive prevented the adhesive from seeping into the diffraction grating.

[0003]

However, in the prior art as shown above, since the bonding from the side is partial and not surface bonding, sufficient bonding strength cannot be secured. Due to the curing of the adhesive, there is a problem that an optical distortion is generated due to a shift between the optical components, and as a result, a wavefront aberration of the optical element is increased.

[0004] That is, if surface bonding is performed with a low-viscosity adhesive on a surface on which fine processing has been performed, the adhesive permeates the fine processing part. For example, if the microfabrication is a diffraction grating, if the adhesive is soaked where air is supposed to be, the refractive index will be high, and diffraction will not be possible within the target design range. was there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has an object to secure a bonding area by surface bonding between optical components to improve bonding strength, and to prevent an adhesive from penetrating into a fine processing region. The first object is to avoid this.

It is a second object of the present invention to reduce the wavefront aberration by realizing surface bonding of an optical element having a diffraction grating and reducing optical distortion.

[0007]

According to a first aspect of the present invention, there is provided a method for bonding an optical component, comprising the steps of: using a reactive curable adhesive which cures in response to specific light irradiation or heating; In an optical component bonding method of bonding an optical component using the optical component, fine processing is performed on a partial region of one of the first surface and the second surface of the optical component to be bonded,
A first step of applying the reactive curable adhesive to a plane of the optical component that has not been subjected to the fine processing and facing the plane excluding the fine processing area, and semi-curing the adhesive; A second step of joining the optical components which have been applied in the step and have been subjected to the fine processing to the surface in a semi-cured state, and a third step of completely curing the optical components joined in the second step And

That is, a reaction-curable adhesive that cures in response to specific light irradiation or heating is applied to an optical component surface different from the optical component surface on which microfabrication has been performed, and this is placed in a semi-cured state. After that, the optical component surfaces subjected to the fine processing are joined and completely cured, thereby realizing surface bonding and avoiding penetration into the fine processing region.

Further, in the optical component bonding method according to the present invention, the reactive curable adhesive may include an ultraviolet curable resin which cures in response to ultraviolet irradiation light, and / or a heating which cures by heating. A curable resin is used.

That is, in the first aspect, by using an ultraviolet curable resin and / or a heat curable resin as the reactive curable adhesive, the cured state of the adhesive can be controlled relatively easily. Bonding work is ensured.

According to a third aspect of the present invention, in the optical pickup device using an optical element having a diffraction grating, the optical element is disposed between two prisms and a slope of the prism. 2. A diffraction grating is applied to one of the surfaces of the parallel flat plate, wherein the prism inclined surface and the prism inclined surface are in contact with each other, and the prism inclined surface and the parallel flat plate are in accordance with claim 1. The bonding is performed based on the optical component bonding method.

That is, by bonding the hologram optical element portion of the optical pickup device using the diffraction grating to the surface using the above-described optical component bonding method, the bonding area can be secured in a larger range as compared with the conventional build-up bonding. Therefore, the optical distortion of the optical element can be suppressed to the minimum level.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical component bonding method and an optical pickup device according to the present invention will be described with reference to the accompanying drawings.
[Embodiment 1] and [Embodiment 2] will be described in detail in this order.

[Embodiment 1] First, Embodiment 1
The method of bonding the optical components will be described in the order of (bonding example 1), (bonding example 2) and (bonding example 3).

(Adhesion Example 1) Here, a case where a photocurable resin is used as an adhesive will be described by taking an ultraviolet curable resin generally used as an adhesive as an example.

FIG. 1 is an explanatory view showing an example of a bonding process of an optical component according to bonding example 1, wherein (1) is a first step,
(2) is the second step, and (3) is the third step. In the figure, 101 is an optical component A to be bonded, and 102 is another optical component B to be bonded.
In this example, in this example, the b surface of the optical component B is subjected to fine processing such as a diffraction grating.

First, in the first step of (1),
UV curable resin 1 on one surface (a surface) of optical component A101
03 is applied. The UV-curable resin used here has a low viscosity (for example, several hundred cp or less). Also, it is good to spread it thinly with a spinner or the like in order to apply it evenly on the a surface.

After the ultraviolet curable resin 103 is uniformly applied to the a surface of the optical component A101, the adhesive surface (a surface) is irradiated with ultraviolet light using an ultraviolet irradiation device 104. However, at this time, a semi-cured state in which the ultraviolet curable resin 103 is not completely cured is set.

Next, in the second step of (2),
The optical component A101 to which the adhesive prepared in the first step is applied, and the optical component B102 to which fine processing has been applied.
And are joined. In this case, the surfaces a and b are joined with an appropriate pressure.

Further, in the third step (3), ultraviolet rays are again radiated by using the ultraviolet irradiating device 104 in the state of bonding in the second step to completely cure the ultraviolet curable resin 103 portion. .

When the diffraction grating is provided on the surface a, the ultraviolet curable resin 103 is applied to the surface b and adhered in the same process as described above.

Here, the ultraviolet curable resin 10 of the bonding example 1 is used.
As No. 3, for example, XNR5 manufactured by Ciba-Geigy Japan
491 (ultraviolet curable adhesive) or 3042 (ultraviolet curable and heat curable adhesive) manufactured by Three Bond Co., Ltd. can be used.

(Adhesion Example 2) Here, an adhesion method using a heat-curable resin instead of the ultraviolet-curable resin 103 used in Adhesion Example 1 will be described. Therefore, FIG. 2 will be described with reference to FIG. 1 in which a heat-curable resin 201 is used instead of the ultraviolet-curable resin 103 and a heating device 202 is used instead of the ultraviolet irradiation device 104.

FIG. 2 is an explanatory view showing an example of a bonding process of an optical component according to the embodiment, wherein (1) shows a first step,
(2) is the second step, and (3) is the third step. In the figure, 101 is an optical component A to be bonded, and 102 is another optical component B to be bonded.
In this example, in this example, the b surface of the optical component B is subjected to fine processing such as a diffraction grating.

First, in the first step of (1),
Heat-curable resin 20 is applied to one side (a-side) of optical component A101.
1 is applied. The thermosetting resin 2 used here
01 has a low viscosity (for example, several hundred cp or less). Also, it is good to spread it thinly with a spinner or the like in order to apply it evenly on the a surface.

When the thermosetting resin 201 is uniformly applied to the a surface of the optical component A101, the heating device 202 is used to heat the adhesive surface (a surface). However, at this time, a semi-cured state in which the thermosetting resin 201 is not completely cured is set.

Next, in the second step of (2),
The optical component A101 to which the adhesive prepared in the first step is applied, and the optical component B102 to which fine processing has been applied.
And are joined. In this case, the surfaces a and b are joined with an appropriate pressure.

Further, in the third step (3), the heating device 2
Using 02, heating is performed again to completely cure the thermosetting resin 201 portion.

When the diffraction grating is applied to the surface a, the thermosetting resin 201 is applied to the surface b and adhered in the same process as described above.

Here, the thermosetting resin 201 of the bonding example 2 was used.
For example, 3042 (ultraviolet curable and heat curable adhesive) manufactured by Three Bond Co., Ltd. can be used.

(Adhesion Example 3) Next, in this adhesion example 3, the ultraviolet curable resin 103 and the heat curable resin 2 described above were used.
01 is used together. Here, when the heat-curable resin is used in combination with the ultraviolet-curable resin, the adhesive is irradiated with ultraviolet rays for the semi-curing (first step) and for the complete curing (third step).
Step (2).

As described above, in the three bonding examples, even if fine processing is performed on the bonding surface despite the surface bonding, the bonding is performed in a semi-cured state and the bonding is performed, so that the adhesive seeps into the processed area. Can be avoided. Further, it is also possible to perform surface bonding only on a necessary area.

Furthermore, the bonding area is larger than that of the so-called overlay bonding using an adhesive having a high viscosity on the side surfaces of the two optical components without surface bonding. For this reason, the distortion at the time of curing the adhesive is dispersed over a wide area, and as a result, the optical distortion can be reduced. If the optical distortion is small,
Wavefront aberration is also reduced.

[Second Embodiment] Next, the first embodiment will be described.
An example of an optical bipping-up device using the bonding method described above will be described.

(Configuration of Second Embodiment) FIG. 3 is an explanatory diagram showing a configuration of an optical pickup device according to a second embodiment. This optical pickup device includes an LD (laser diode) 301 with a PD (photodetector), a hologram optical element 302 provided with a diffraction grating, a collimator lens 303, and an objective lens 304. Reference numeral 305 denotes an optical disk.

The hologram optical element 302 includes a quarter-wave plate 306 and two prisms 307 to 308.
And the parallel plate 309 are joined. The diffraction grating is provided on both sides of the parallel plate 309 or on the slopes of the two prisms 307 to 308.
Note that the collimating lens 303 can be omitted.

On the surface of the parallel plate 309 on the LD 301 side, there is one type of diffraction grating, and the quarter wavelength plate 306
There are at least three types of diffraction gratings on the side. Note that these diffraction gratings may be any diffraction grating as long as they do not affect this embodiment.

(Operation of Embodiment 2) Next, the operation of the optical pickup device configured as described above will be described. Light emitted from the LD 301 enters the hologram optical element 302. The light is incident on the diffraction grating by a parallel flat plate (or a prism slope). If the diffraction grating is a polarization-dependent diffraction grating, most of the light traveling toward the optical disk 305 can be transmitted. Incident light is 1/4
The light is converted into circularly polarized light by the wavelength plate 306, is converted into parallel light by the collimator lens 303, and is condensed on the optical disk 305 by the objective lens 304.

The reflected light from the optical disk 305 returns through the objective lens 304 and the collimating lens 303, and the direction of polarization of the original LD light is 90 ° by the quarter-wave plate 306.
The polarization direction is rotated by °, that is, the polarization direction is orthogonal to the original polarization direction. Further, the reflected light is diffracted by a diffraction grating, and each diffracted light enters each PD. In this embodiment, the knife edge method is used for focusing, and the push-pull method is used for tracking. However, other methods may be used as long as they do not affect the effects of the present invention.

The two prisms 307 to 308 and the parallel plate 309 among the components constituting the hologram optical element 302 of the optical pickup device are bonded using the bonding method described in the first embodiment.

That is, as shown in FIG. 4, when a diffraction grating is provided on both sides of the parallel plate 309, for example, the ultraviolet curable resin 103 is first applied to the slopes of the two prisms 307 to 308. Then, it is irradiated with ultraviolet rays to keep it in an incompletely cured state. These two parallel plates 309
It is sandwiched between the three prisms 307 to 308 and further irradiated with ultraviolet rays to be completely cured. The quarter-wave plate 30
6 may be bonded to the prism 307 in advance. The surface bonding in this case uses a normal bonding method.

As shown in FIG. 5, when a diffraction grating is formed on the slopes of the two prisms 307, first, the parallel plate 309 is coated with the ultraviolet curable resin 103. Then, it is irradiated with ultraviolet rays to keep it in an incompletely cured state.
Both sides of the parallel plate 309 are sandwiched between two prisms 307 to 308 provided with a diffraction grating, and further irradiated with ultraviolet rays to be completely cured. The quarter-wave plate 306 may be bonded to the prism 307 in advance. The surface bonding in this case uses a normal bonding method.

In the above-mentioned bonding example, the ultraviolet curable resin 103 was used as the above-mentioned adhesive. Of course, the above-mentioned bonding example 2 (heat-curable resin) and bonding example 3 (ultraviolet-curable resin and heat-curable resin) were used. May be used.

As described above, according to the optical component bonding method according to the present invention (claim 1), a specific light is applied to an optical component surface different from the optical component surface on which fine processing is performed. Applying a reactive curable adhesive that cures in response to irradiation or heating, and after making it a semi-cured state, joins the optical parts that have been subjected to microfabrication and completely cures them, realizing surface bonding In addition, it is possible to prevent penetration into the fine processing region.

Further, according to the optical component bonding method according to the present invention (claim 2), since the ultraviolet curable resin and / or the heat curable resin are used as the reactive curable adhesive in claim 1, The cured state of the agent can be controlled relatively easily, and the bonding operation is ensured.

Further, according to the optical pickup device of the present invention (claim 3), the hologram optical element portion of the optical pickup device using the diffraction grating is surface-bonded by using the above optical component bonding method. Since the bonding area is secured in a larger range as compared with the conventional build-up bonding, the optical distortion of the optical element can be suppressed to the minimum level, and the wavefront aberration of the optical element can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a bonding process of an optical component according to a bonding example 1 , (1) is a first step, (2) is a second step, and (3) is a third step.

FIG. 2 is an explanatory view showing an example of a bonding process of an optical component according to bonding example 2, (1) is a first step, (2) is a second step, and (3) is a third step.

FIG. 3 is an explanatory diagram illustrating a configuration of an optical pickup device according to a second embodiment.

FIG. 4 is an explanatory view showing a method of bonding a hologram optical element when diffraction gratings are provided on both sides of a parallel plate according to the second embodiment.

FIG. 5 is an explanatory diagram showing a method of bonding hologram optical elements when diffraction gratings are provided on the slopes of two prisms according to the second embodiment.

FIG. 6 is an explanatory view showing a conventional method of bonding optical components.

[Explanation of symbols]

 Reference Signs List 101 optical component A 102 optical component B 103 ultraviolet curable resin 201 heat curable resin 302 hologram optical element 307, 308 prism 309 parallel plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G11B 7/22 G11B 7/22 // B29L 11:00

Claims (3)

(57) [Claims] An optical component bonding method for bonding an optical component using a reactive curable adhesive that cures in response to specific light irradiation or heating, wherein the first surface of the optical component to be bonded and the second surface are bonded to each other. The reactive curable adhesive is applied to a plane of the optical component which has not been subjected to micro-machining and which has been subjected to micromachining on a partial area of one of the faces, and which faces a plane excluding the micromachining area. And then semi-curing the adhesive.
And a second step of joining the optical components which have been applied in the first step and which have been subjected to the fine processing to the semi-cured surface, and the optical components joined in the second step. A third step of completely curing the
An optical component bonding method, comprising: 2. The method according to claim 1, wherein the reactive curable adhesive is an ultraviolet curable resin that cures in response to ultraviolet irradiation light or a heat curable resin that cures by heating. The optical component bonding method according to the above. 3. An optical pickup device using an optical element having a diffraction grating, wherein the optical element is composed of two prisms and a parallel flat plate disposed between slopes of the prisms. 2. A diffraction grating is applied to one of the surfaces of the parallel plate that comes into contact with the slope, and the prism slope and the parallel plate are bonded based on the optical component bonding method according to claim 1. Optical pickup device.