JP2002118307A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser light source which has stable output even if the temperature changes, and is excellent in durability to temperature change. SOLUTION: This is an optical device where an alicyclic epoxy compound having an epoxy group, a compound having an oxycetanyl group, and an adhesive composition containing an onium salt photoreaction initiator as much as a catalyst and a photosensitizer are inserted between adherends consisting of a plurality of optical parts so that the thickness of adhesion may be not less than 0.05 μm and not more than 5 μm, and then they are hardened by visible beam 390-500 nm in wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical device, and more particularly, to a laser light source. The laser light source includes a laser diode-excited solid-state laser that excites a solid-state laser crystal with a semiconductor laser (laser diode).

[0002]

2. Description of the Related Art In order to record and reproduce information by light and to improve the recording density, a small light source capable of obtaining a short wavelength is required. Converting laser light sources are becoming increasingly important. This laser-diode-pumped solid-state laser and a method for manufacturing the same are known, for example, from Japanese Patent Application Laid-Open No. 8-186308.
A laser diode-pumped solid-state laser that excites a solid-state laser crystal to which a rare earth element such as neodymium is added by light emitted from a semiconductor laser is disclosed. Often this type of laser has a cavity
A Fabry-Perot resonator consisting of two resonator mirrors is used.

In this type of laser light source, in order to maintain stable laser oscillation, it is necessary that the length of the resonator (the distance between the mirror surfaces of the two resonator mirrors) does not change significantly due to a change in ambient temperature. This is because, if the resonator length changes, the laser output and the longitudinal mode change, or noise is generated. More specifically,
It is necessary to suppress the change in the cavity length to at least 1/4 or less of the oscillation wavelength. Considering that the oscillation wavelength of many laser diode-pumped solid-state lasers is around 1 μm, ideally, the change in the cavity length is approximately 0 μm. .25 μm or less. JP-A-8-186308 discloses that the layer thickness of the adhesive for fixing the resonator mirror to the holder is 5 μm or less. An example of the adhesive is a two-part mixed / room temperature curing type epoxy adhesive, but this adhesive has insufficient bonding speed and bonding durability. JP-A-9-291267 and the like disclose the use of an ultraviolet-curable adhesive composition. However, even if the adhesive compositions disclosed in these publications are used, improvement is insufficient. there were. The present inventors have considered that in an optical device such as a laser light source, in view of the importance of an adhesive composition for bonding and fixing an optical component, it is possible to adhere to a member that does not substantially transmit ultraviolet light, The present inventors have intensively searched for an improved adhesive composition and an improved bonding method which are excellent and have excellent durability by a temperature cycle test and the like, and have led to the present invention.

[0004]

The first object of the present invention is to provide an optical device having one or more optical components such as a light source, a lens, a mirror, etc. Improving sex, second,
An object of the present invention is to provide an improved method for manufacturing an optical device. The third object of the present invention is to provide a laser light source which has a stable output even when the temperature changes and has excellent durability against the temperature change. Fourth, improvement of optical components of the laser light source. To provide a customized mounting method. Another object of the present invention is to provide an adhesive composition for an optical component having excellent adhesive strength, and still other objects are
It will be clear from the following description.

[0005]

SUMMARY OF THE INVENTION The above objects of the present invention are as follows.
This has been achieved by the following configuration. Item 1) An adhesive composition containing an alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, a catalytic amount of an onium salt photoinitiator, and a photosensitizer is coated with a plurality of optical components. Adhesion thickness of 0.05μ between clothes
m and 5 μm or less.
An optical device characterized by being cured by visible light of up to 500 nm (hereinafter also referred to as "short wavelength visible light"). Item 2) The optical device according to Item 1), wherein the adhesive composition contains imide acrylate or imide methacrylate represented by the following general formula (1). A— (CH ₂ —CH ₂ —O) _n —B (1) In the formula, A represents an imide group, n represents an integer of 1 or 2, and B represents an acryloyl group or a methacryloyl group. Item 3) The optical device according to Item 1), wherein the adhesive composition contains a silane coupling agent. Item 4) The optical device according to Item 1) or 2), wherein the adhesive composition contains spherical silica particles having an average diameter of 0.1 µm or more and 1.0 µm or less. Item 5) The optical device according to Item 1) or Item 2), wherein the adherend is an inorganic member that does not substantially transmit a metal member and ultraviolet rays and transmits visible light having a wavelength of 390 to 500 nm. Item 6) The optical device according to any one of Items 1) to 5), wherein the compound having an oxetanyl group is represented by the following general formula (2).

Embedded image In the formula (2), R ₁ represents a methyl group or an ethyl group. R
₂ represents a hydrocarbon group having 6 to 12 carbon atoms. Item 7) The optical device according to any one of Items 1) to 6), wherein the optical device is a laser-diode-pumped solid-state laser having a Fabry-Perot resonator constituted by two resonator mirrors. Item 8) The composition contains an alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, a catalytic amount of an onium salt photoinitiator, and a photosensitizer, and has a viscosity at room temperature of 10 mPa · S or more and 1,000 mPa · S or less, and the adhesive composition having a contact angle with the adherend of 40 degrees or less such that the adhesive thickness between the adherends composed of a plurality of optical components is 0.05 μm or more and 5 μm or less. After inserting into
A method for producing an optical device, comprising curing with visible light having a wavelength of 390 to 500 nm.

Hereinafter, the present invention will be described in detail. In the present invention, the optical device refers to an apparatus having at least one optical component selected from the group consisting of optical components such as a light source, a lens, a plane reflecting mirror, a concave mirror, a convex mirror, and a diffraction grating. In addition, the optical component is often made of a single-crystal silicon or the like, in addition to an adherend (a metal member such as copper, a copper alloy, or aluminum) such as a holder for bonding and fixing these optical components. ), The optical device of the present invention is composed of a plurality of optical components. Specific examples of the optical device of the present invention include components such as a laser light source, an optical reader, an optical pickup, and a final product using these components. This end product includes digital printers that make color prints from the recording media of photographic films and electronic still cameras.

In the present invention, "substantially does not transmit ultraviolet light" means that the transmittance in the wavelength range of 200 to 335 nm is 10% or less, and the transmittance in the wavelength range of 360 to 365 nm is 10% or less. Yes, and 365
It means that the transmittance in the wavelength range of 370 nm is 30% or less. In addition, this "substantially does not transmit ultraviolet light"
Preferably, the transmittance in the wavelength range of 200 to 335 nm is 1% or less, the transmittance in the wavelength range of 360 to 365 nm is 2% or less, and 365 to 3 nm.
It means that the transmittance in the wavelength range of 70 nm is 25% or less.

The adhesive composition of the present invention contains, as essential components, an alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, a catalytic amount of an onium salt photoreaction initiator, and a photosensitizer. These compounds, initiators,
Each of the photosensitizer and the photosensitizer may be a single type or a mixture of two or more types.

In the present invention, an epoxy compound having two or more epoxy groups in one molecule can be used. As the epoxy compound, an alicyclic structure having two or more epoxy groups in one molecule can be used. Than glycidyl compounds without
An alicyclic epoxy compound having two or more epoxy groups in one molecule is preferably used. The “alicyclic epoxy compound having an epoxy group” refers to one molecule of a partial structure obtained by epoxidizing a double bond of a cycloalkene ring such as a cyclopentene group or a cyclohexene group with an appropriate oxidizing agent such as hydrogen peroxide or peracid. Refers to a compound having two or more. As the alicyclic epoxy compound having an epoxy group of the present invention, a compound having two or more cyclohexene oxide groups or cyclopentene oxide groups in one molecule is preferable. Specific examples of such alicyclic epoxy compounds include 4-vinylcyclohexenedioxide, (3,4-epoxycyclohexyl) methyl-3,4-epoxycyclohexylcarboxylate, and di (3,4-epoxycyclohexyl) adipate. , Di (3,4-epoxycyclohexylmethyl) adipate, bis (2,3-epoxycyclopentyl) ether, di (2,3-epoxy-6-methylcyclohexylmethyl) adipate, dicyclopentadienedioxide. One type of alicyclic epoxy compound having an epoxy group may be used, or a mixture of two or more types may be used. Various alicyclic epoxy compounds are commercially available, Union Carbide Japan Co., Ltd.
Available from Daicel Chemical Industries, Ltd. and others.

A glycidyl compound having two or more epoxy groups in one molecule and having no alicyclic structure can be used in combination with the alicyclic epoxy compound of the present invention in an amount equal to or less than about the same weight. Examples of such a glycidyl compound include a glycidyl ether compound and a glycidyl ester compound, and it is preferable to use a glycidyl ether compound in combination. Specific examples of the glycidyl ether compound include 1,3-bis (2,3-epoxypropoxy) benzene, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, and cresol novolak. Glycidyl ether compounds such as epoxy resin, trisphenol methane type epoxy resin, aromatic glycidyl ether compounds, 1,4-butanediol glycidyl ether, glycerol triglycidyl ether, propylene glycol diglycidyl ether, trimethylolpropane tritriglycidyl ether Compounds. The glycidyl ester includes a glycidyl ester of linolenic acid dimer. The glycidyl compound used in combination with the alicyclic epoxy compound may be one kind or a mixture of two or more kinds. Glycidyl ethers are commercially available from Yuka Shell Epoxy Co., Ltd.

The compound having an oxetanyl group of the present invention (hereinafter, also simply referred to as "oxetane compound") is 1
It is a compound having one or more oxetanyl groups in the molecule. The oxetanyl group-containing compound is roughly classified into a compound having one oxetanyl group in one molecule and a compound having two or more oxetanyl groups in one molecule.

The monofunctional oxetane compound having one oxetanyl group in one molecule is represented by the following general formula (2)
The compound represented by is preferred.

Embedded image In the formula (2), R ₁ represents a methyl group or an ethyl group. R
₂ represents a hydrocarbon group having 6 to 12 carbon atoms. As the hydrocarbon group for R ₂ , a phenyl group or a benzyl group can be used, but an alkyl group having 6 to 8 carbon atoms is preferable, and a branched alkyl group such as a 2-ethylhexyl group is particularly preferable. R
Examples of the oxetane compound in which ₂ is a phenyl group are described in JP-A-11-140279. Examples of oxetane compounds in which R ₂ is a benzyl group which may be substituted are described in JP-A-6-16804. Oxetane compounds in which R ₁ is an ethyl group and R ₂ is a 2-ethylhexyl group are preferably used in the present invention as excellent diluents, curing accelerators, softeners, and surface tension lowering agents. .

In the present invention, a polyfunctional oxetane compound having two or more oxetanyl groups in one molecule can be used. A preferred compound group is represented by the following general formula (3).

Embedded image In the formula (3), m represents a natural number of 2, 3 or 4, and Z represents an oxygen atom, a sulfur atom, or a selenium atom. R ₃ is a hydrogen atom, a fluorine atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a fluoroalkyl having 1 to 6 carbon atoms, an allyl group, a phenyl group or a furyl group. R
₄ is an m-valent linking group, preferably a group having 1 to 20 carbon atoms, which may contain one or more oxygen atoms and sulfur atoms. Z is preferably an oxygen atom, R ₃ is preferably an ethyl group, m is preferably 2, and R ₄ is preferably a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched poly (alkyleneoxy) group. Compounds obtained by combining any two or more of the preferable examples for R ₃ , R ₃ , R ₄ , Z, and m are more preferable.

The onium salt photoreaction initiator of the present invention refers to an onium salt which is considered to generate an active chemical species by irradiating the adhesive composition with active visible light in the presence of a photosensitizer. . As the onium salt photoreaction initiator, an aromatic iodonium salt, an aromatic sulfonium salt and the like are preferable because they are relatively stable thermally. Here, the active visible light is light in a visible region capable of generating a chemically active species (cationic species such as Lewis acid and Bronsted acid) capable of initiating a chemical reaction by acting on an onium salt, and having a wavelength of 390 n.
Visible light of m to 500 nm is preferably used.

When an aromatic sulfonium salt or an aromatic iodonium salt is used as an onium salt photoinitiator, BF ₄ ⁻ , AsF ₆ ⁻ , Sb
F ₆ ⁻ , PF ₆ ⁻ , PF ₆ ⁻ , B (C ₆ F ₅ ) ₄ ^{− and the} like. As the initiator, a PF ₆ salt or an SbF ₆ salt of an aromatic sulfonium can be preferably used because it has solubility and moderate polymerization activity. Further, in order to improve solubility, one or more alkyl groups or alkoxy groups having 1 to 10 carbon atoms are introduced into an aromatic group of an iodonium salt or an aromatic sulfonium salt, usually a phenyl group. Chemical structures are preferred. The PF ₆ salt or SbF ₆ salt of an aromatic sulfonium salt is commercially available from Union Carbide Japan Co., Ltd. or the like. Asahi Denka Kogyo Co., Ltd. also sells PF ₆ salt of aromatic sulfonium under the trade name of ADEKA OPTOMER SP series. Nippon Soda Co., Ltd. also sells a PF ₆ salt of aromatic sulfonium under the trade name of the cationic polymerization initiator “CI series”. Aromatic sulfonium salts have an absorption up to about 360 nm and aromatic iodonium salts have an absorption up to about 320 nm.

Among the chemical structural formulas shown below, sulfonium salts PI-3 and PI-4 are preferably used in the present invention.

[0017]

Embedded image

[0018]

Embedded image

As the photosensitizer, an adhesive composition containing an onium salt photoinitiator can be used in a visible light, preferably 390-500.
It is a compound for making the present composition curable with respect to visible light in the range of nm. It is considered that the light energy absorbed by the photosensitizer is transferred to a coexisting photoreaction initiator to generate a cation species and / or a radical cation species for initiating a curing reaction in the photoreaction initiator. As another initiation mechanism, it is considered that the photosensitizer generates an active chemical species from an excited state and generates a reaction initiating species of a photoinitiator. The photosensitizer preferably used in the present invention includes thioxanthones, acetophenones, benzophenones, and 9.1, which have absorption at 390 to 500 nm.
0-dialkoxyanthracenes, among which 9.1
0-Dialkoxyanthracenes are particularly preferred. Specific examples of this compound are described in JP-A-11-329552. Hereinafter, specific examples of the photosensitizer of the present invention will be described.

[0020]

Embedded image

The onium salt photoreaction initiator of the present invention generates an active cation species or a cation radical species by using light energy absorbed by a photosensitizer to form an alicyclic epoxy compound or an oxetanyl group. A compound having
It is considered that the adhesive composition of the present invention is cured by polymerizing imide acrylate or imide methacrylate.

In the adhesive composition of the present invention, the weight ratio of the alicyclic epoxy compound and the oxetane compound is (95
To 40) parts by weight to (5 to 60) parts by weight;
Preferably, (80 to 60) parts by weight to (20 to 40) parts by weight. If the amount of the monofunctional oxetane compound is too small, the liquid properties such as the viscosity and surface tension of the adhesive composition are not good. Conversely, if the amount of the monofunctional oxetane compound is too large, the cured product becomes too flexible, and the adhesive strength becomes too high. Decrease.
Also, the onium salt photoreaction initiator may be used in a catalytic amount,
The photosensitizer may be any amount that is sufficient to absorb visible light of 390 to 500 nm and start a curing reaction of the composition. Total 10 of cyclic epoxy compound and oxetane compound
0.3 to 10 parts by weight with respect to 0 parts by weight,
0.5 to 5 parts by weight is a preferred range.

The adhesive composition of the present invention can contain imide acrylate or imide methacrylate. The imide group portion of these imide (meth) acrylates (imide acrylate or imide methacrylate) is represented by the formulas (3) to (7). The imide (meth) acrylate that can be used in the present invention is disclosed in JP-A-10-36462.
And No. 11-21470.

[0024]

Embedded image

However, in the formulas (3) to (7), R ₁
To R ₄ are a hydrogen atom, a halogen atom or C _n H _{2n + 1} , and n =
R _{1 to} R _{4 in} one molecule may be the same or different. Examples of the halogen atom include fluorine, chlorine, bromine and iodine atoms.

The imide (meth) acrylate compounds containing imide groups represented by the formulas (3) to (7) can be synthesized by the methods described in the following documents and patents. -Kiyoshi Kato et al., Journal of the Society of Synthetic Organic Chemistry, 30 (10), 89
7, (1972)-Javier de Abajo et al., Polymer, vol33.
(5), (1992)-JP-A-56-53119,-JP-A-1-242569.

In particular, the imide (meth) acrylate compounds containing imide groups represented by formulas (3) to (7), which are preferably used in the present invention, can be synthesized in one pot. For example, these compounds are a dehydration condensate of an N-hydroxyalkylphthalimide derivative, an N-hydroxyalkylhexahydrophthalimide derivative, an N-hydroxyalkylsuccinimide derivative or an N-hydroxyalkyltetrahydrophthalimide derivative with (meth) acrylic acid It can be obtained in one pot by the reaction. Further, the compounds represented by the formulas (3), (4), (6) and (7) are obtained by converting the starting N-hydroxyalkylphthalimide derivative, N-hydroxyalkylhexahydrophthalimide derivative or N-hydroxyalkyltetrahydrophthalimide derivative. Phthalic anhydride, hexahydrophthalic anhydride or tetrahydrophthalic anhydride derivative, and the addition reaction of amino alcohols and the subsequent dehydration reaction, can be synthesized in one pot without protecting the unsaturated group. The reaction proceeds quantitatively.

Preferred examples of the imide (meth) acrylate having an imide group of the formulas (3) to (7) are as follows.

[0029]

Embedded image

In the optical device and the method of manufacturing the same according to the present invention, the adhesive composition is inserted between adherends comprising a plurality of optical components so that the adhesive thickness is 0.05 μm or more and 5 μm or less. If the thickness is less than the thickness, the adhesive strength is insufficient. If the thickness is more than the thickness, the adhesive tends to be adversely affected by curing shrinkage. A bond thickness of 0.05 μm or more and 2 μm or less is preferable, and a bond thickness of 0.2 μm or more and 1 μm or less is particularly preferable.

It is preferable to further add a silane coupling agent to the adhesive composition of the present invention. It is considered that the silane coupling agent has a property of chemically bonding the adhesive composition with an inorganic member or a metal member as an optical component and an adherend thereof. The combined use of the silane coupling agent can improve the adhesive strength and the adhesive durability. As the silane coupling agent used in the present invention, epoxysilanes having an epoxy group and a trimethoxysilyl group in one molecule are preferably used. Such coupling agents are available from Shin-Etsu Chemical Co., Ltd.
It is available under trade names such as M303, KBM403 and KBE402. The preferred use range of the silane coupling agent is 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, based on 100 parts by weight of the total of the alicyclic epoxy compound and the oxetane compound.

It is preferred that the adhesive composition of the present invention contains spherical silica particles. Silica particles are 0.1μ
It is preferred that they have a diameter of m to 2 μm and the particle size distribution is as uniform as possible. Average particle size is 0.2μm or more and 0.8μm
The following particles are preferably used in the present invention, and silica particles having a shape close to a true sphere and containing few ionic impurities are particularly preferably used. By adding the silica particles, the heat durability of the cured adhesive composition can be improved. The amount of the spherical silica particles added is determined by the adhesive composition 1.
It can be appropriately selected within the range of 1 to 20 parts by weight with respect to 00 parts by weight. Synthetic quartz spherical silica is commercially available from Tatsumori Corporation.

The adhesive composition of the present invention comprises an inorganic transparent member such as a lens and a reflecting mirror and a metal (copper, copper,
It is preferably used for bonding to metal members such as a holder made of copper alloy, aluminum, etc.).

The present inventors have conducted intensive studies and found that the viscosity of the adhesive composition at room temperature (25 ° C.) was 10 mPa · s or more,
It is preferable to adjust the pressure to 1,000 mPa · s or less,
More preferably, the viscosity is adjusted to 80 mPa · s or more and 300 mPa · s or less, and in addition, the contact angle between the adhesive composition and the adherend is 40 ° or less, more preferably 30 ° or less. Has been found to give good adhesive fixation. In order to adjust the viscosity of the composition, it is effective to add a monofunctional oxetane compound. or,
If necessary, the contact angle can be adjusted by adding a fluorine-based surfactant. The fluorinated surfactant is a surfactant having fluorocarbon as a hydrophobic group, and there are three kinds of anions, cations and nonions,
In the present invention, it is preferable to use a fluorinated alkyl ester-based nonionic surfactant. The addition amount of the nonionic surfactant is 0.1 to 1 part by weight based on 100 parts by weight of the adhesive composition. This nonionic surfactant was obtained from Sumitomo 3M Co., Ltd. and others using Florad (FC170C, 1).
71, 430, 431, etc.).

Inert components such as dyes and pigments can be appropriately added to the adhesive composition of the present invention in addition to the above-mentioned additives. In addition, for the purpose of improving photocurability, pyrene,
Perylene, acridine orange, thioxanthone, 2-
Photosensitizers such as chlorothioxanthone and benzopyran may be added. Various light sources can be used as a short-wavelength visible light source for curing the adhesive composition of the present invention, for example, a metal halide light source, an ultra-high pressure mercury lamp, a mercury arc lamp, a xenon arc lamp, a carbon arc lamp, and a tungsten-light source. Halogen copy lamps.

The method for manufacturing an optical device according to the present invention will be described below with reference to a method for manufacturing a laser diode pumped solid-state laser. According to an embodiment of the manufacturing method of the present invention, when the optical component for determining the resonator length of the laser diode-pumped solid-state laser is adhesively fixed to a component mounting surface that intersects the resonator axis of the holder, the component mounting surface After the optical components are brought into close contact with each other, the adhesive is allowed to penetrate through the gap between the two, and then the wavelength is 390 nm to 500 nm.
Is irradiated with visible light containing the short-wavelength visible light component. In the method for producing an optical device of the present invention, the composition contains an alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, and a catalytic amount of an onium salt photoinitiator, and has a viscosity at room temperature of 10 mPa · S or more. 1,
000 Pa · S or less, and the contact angle with the adherend is 30
After the adhesive composition having a degree of adhesion of not more than 0.05 is inserted between adherends comprising a plurality of optical components so that the adhesion thickness becomes 0.05 μm or more and 5 μm or less, the composition is cured with active energy rays. After insertion so that the adhesive thickness becomes 0.05 μm or more and 2 μm or less, it is preferable to cure.

[0037]

When the adhesive composition of the present invention is used for bonding a resonator mirror, the curing shrinkage rate (linear shrinkage rate) when the adhesive is cured.
Is about 2%. Therefore, if the thickness of the adhesive layer on the mirror mounting surface is adjusted to 5 μm or less, the shrinkage of the uncured portion of the adhesive layer is 5 × even if the curing shrinkage proceeds.
0.02 = about 0.1 μm. Therefore, even when considering the sum of the two mirror mounting surfaces, the curing shrinkage of the adhesive layer (that is, the change over time of the resonator length) is about 0.2 μm, which is twice as large as the above, and is 0.25 μm or less as described above. It will be suppressed.

In this manner, the change over time of the resonator length becomes 1/4 or less of the oscillation wavelength (around 1 μm), and it is possible to prevent the laser output and the longitudinal mode from fluctuating or generating noise. Further, the adhesive composition of the present invention is capable of penetrating uniformly even when the distance between an optical component and a metal adherend or the like is reduced to about 1 μm, and is strong even after being cured by short wavelength visible light or the like. In order to produce a flexible cured product,
In a wide temperature range from a low temperature (−25 ° C.) to a high temperature (70 ° C.), adhesion without peeling can be realized, and the adhesive strength is higher than the adhesive strength obtained by ultraviolet irradiation.

By making the surface roughness of the mirror mounting surface less than the oscillation wavelength, the adhesive can be easily spread uniformly and widely. Therefore, by making the adhesive layer thinner to about 0.3 to 0.6 μm, The amount of change in the resonator length can be further reduced.

[0040]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a laser diode-pumped solid-state laser according to one embodiment of the present invention. This laser diode pumped solid-state laser is a semiconductor laser in a chip state that emits a laser beam 10 as pumping light.
A condensing lens 12 for converging the laser beam 10 which is divergent light; and a YAG crystal (hereinafter, Nd: YA) which is a solid-state laser medium doped with neodymium (Nd).
(Referred to as a G crystal) 13 and a resonator mirror 14 disposed on the front side (right side in the figure) of the Nd: YAG crystal 13.

The resonator mirror 14 and Nd: YA
Between the G crystal 13 and the Nd: YAG crystal 13 side,
A KNbO ₃ crystal (hereinafter, referred to as a KN crystal) 15, which is a nonlinear optical material, and an etalon 16 made of a quartz plate are arranged.

The semiconductor laser 11 has a wavelength of 809n.
Those that emit a laser beam 10 of m are used.
The Nd: YAG crystal 13 excites neodymium ions by the incident laser beam 10 and emits light having a wavelength of 946 nm. End face 13 of Nd: YAG crystal 13 on excitation light incident side
In a, light having a wavelength of 946 nm is well reflected (reflectance
99.9%), laser beam for excitation with wavelength 809nm
10 is provided with a coating that allows good transmission (a transmittance of 99% or more). On the other hand, the mirror surface 14a of the resonator mirror 14 made of quartz is provided with a coating that reflects light having a wavelength of 946 nm well and transmits light having a wavelength of 473 nm described below.

Accordingly, light having a wavelength of 946 nm is confined between the surfaces 13a and 14a to cause laser oscillation.
The second harmonic 19 having a wavelength of 1/2, that is, 473 nm
And the second harmonic 19 is emitted from the resonator mirror 14.

The semiconductor laser 11 and the condenser lens 12 are fixed to a holder 20, while the Nd: YAG crystal 13, the KN crystal 15, the etalon 16 and the resonator mirror 14 are provided in another holder.
21 and these holders 20 and 21 are
It is fixed to. The reference plate 22 is fixed on the Peltier element 24 joined to the heat sink 23.

As described above, in this embodiment, N
d: A Fabry-Perot resonator is constituted by the YAG crystal 13 and the resonator mirror 14, and the portion of the resonator, the semiconductor laser 11, and the condenser lens 12 are driven by a temperature control circuit (not shown) by the Peltier element 24. By being controlled, a predetermined temperature is maintained.

Next, the mounting structure of the laser component to the holder 21 will be described. The holder 21 is made of, for example, copper and is formed in a substantially rectangular tube shape, and both end surfaces thereof are polished so as to be perpendicular to the resonator axis to be mirror mounting surfaces 21a and 21b. The Nd: YAG crystal 13, which also functions as a resonator mirror, has one light passing end face 13 thereof.
b is bonded to the mirror mounting surface 21a so that the holder
Fixed to 21. On the other hand, the resonator mirror 14 is fixed to the holder 21 by adhering a surface 14b following the mirror surface 14a on the outer peripheral side to the mirror mounting surface 21b. Further, the KN crystal 15 and the etalon 16 are adhered to the peripheral wall of a through hole extending in the resonator axis direction in the holder 21 to form the holder 21.
It is fixed to. The adhesive surface 14b of the resonator mirror 14 was brought into close contact with the adhesive surface 21b of the holder, and the adhesive composition of the present invention, which will be described in detail below, was inserted into the gap, and then cured by irradiation with short-wavelength visible light.

(Examples 1 to 11) Adhesive composition of Example 1: UVR 612835 parts manufactured by Union Carbide Japan Co., Ltd. as an alicyclic epoxy compound, and Yuka Shell Epoxy Co., Ltd. as a bisphenol F type epoxy resin Using 80635 parts of Epikote manufactured by Toa Gosei Co., Ltd. as a monofunctional oxetane compound.
212 (EHOX) 30 parts, and using CI 28554 parts manufactured by Nippon Soda Co., Ltd. as a photoreaction initiator,
Using 1 part of DETX-S manufactured by Nippon Kayaku Co., Ltd. as a photosensitizer and 3032 parts of KBM 3030 manufactured by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent. Composition Example 1 was prepared.

The adhesive compositions of Examples 2 to 11 were subjected to a detailed test of an adhesive composition to which imide acrylate was added (hereinafter, also referred to as a “hybrid type”). The test was conducted by changing the type of epoxy resin and the amount of oxetane added.
In the same manner as in Example 1, the components shown in Table 1 were blended in parts by weight as shown in the table to prepare adhesive compositions of Examples 2 to 11. The chemical structures of the used materials are shown in Chemical formulas 10 to 12. Table 1 summarizes the contents of the compounding materials used in Examples 1 to 11, and Tables 2 and 3 together with the obtained adhesive strength results.
Shown in

[0049]

[Table 1]

[0050]

Embedded image

[0051]

Embedded image

[0052]

Embedded image

For the adherend, tellurium copper and quartz glass were used, the thickness of the adhesive between tellurium copper and quartz glass was adjusted to about 2 μm, and a UV spot light source (L5662-01: manufactured by Hamamatsu Photonics KK) was used as a light source. ) Or visible light source (HYPER
Using SPOT (manufactured by Toa Gosei Co., Ltd.), light was applied from the quartz glass side to prepare an adhesive sample. The bonding area was 5 mm × 5 mm. The irradiation conditions were L5662-01.
Distance between the end of the single light guide and tellurium copper is 60m
m, the distance between the single light guide end of HYPER SPOT and tellurium copper was 10 mm, and the irradiation time was 1
50 seconds. The bond strength was determined as follows: 30 ° C.-1 day after bonding, and then a temperature cycle test: −25 ° C.⇔80 ° C.
(Temperature rising and falling = 1 ° C / min, hold at -25 ° C and 80 ° C for 1 hour) × After repeating 6 times, tellurium copper and quartz glass are pulled vertically by a tensile tester, and the strength when they come off Was measured. Table 2 and Table 3 collectively show the measured values of the adhesive strength by ultraviolet (UV) irradiation (UV adhesive strength Kg) and the adhesive strength by short-wavelength visible light irradiation (visible light adhesive strength Kg).

[0054]

[Table 2]

[0055]

[Table 3]

As shown in Tables 2 and 3, Examples 1 to 1
In No. 1, the visible light adhesive strength was larger than the UV adhesive strength. Toagosei Co., Ltd. as imido acrylate
Among the formulations containing TO1429, Examples 2, 3,
And 4 gave particularly high bond strengths. In Example 11, the UV adhesive strength was extremely low, but surprisingly, the visible light adhesive strength was high.

(Examples 20 to 22 and Comparative Example 1) Table 4 shows the formulation and adhesive strength. Photoinitiator CI2855, S
P152 and UVI6990 each have 340n
m, absorption only up to 360 nm and 370 nm, but about 4 nm by photosensitizers DETX-S and SP100.
Photosensitization that can be cured even by visible light up to 20 nm was confirmed, and it was confirmed that curing was possible even with visible light.

[0058]

[Table 4]

CI2855, SP152, UVI699
0 of any photoinitiator is DETX-S, SP100
In the presence of any photosensitizer, from the UV adhesion strength,
It was confirmed that the visible light adhesive strength was increased.

(Examples 23 to 25) Based on Example 22, a test was conducted by changing the epoxy type and the oxetane type.
As shown in Table 5, although the visible light adhesive strength was low in Example 11, high adhesive strength was obtained by adding oxetane.

[0061]

[Table 5]

(Examples 12 to 14) Based on Example 1, the effect of adding TO1429, which is an imide acrylate, was tested as a hybrid test. Table 6 shows the results.

[0063]

[Table 6]

The results of a hybrid test based on Example 1 show that the addition of T01429 (imide acrylate), which is a substance capable of radical polymerization, was investigated. In particular, the visible light adhesive strength was remarkably improved. It has been found that there is an addition amount that maximizes the adhesive strength, and it is considered that the addition amount of T01429 is preferably about 5 to 40 parts, and particularly preferably 10 to 35 parts.

(Examples 15 and 16) A hybrid system was tested based on Example 1. When M210 (a special acrylate manufactured by Toagosei Co., Ltd.) was added as a radical polysynthetic material, as shown in Table 7,
Although visible light adhesive strength larger than V adhesive strength was obtained,
No remarkable improvement in adhesive strength comparable to TO1429 was observed.

[0066]

[Table 7]

The mirror mounting surfaces 21a and 21b are mirror-polished so that the surface roughness is smaller than the oscillation wavelength of the solid-state laser, that is, 946 nm. It should be noted that an ultra-precision cutting finish or the like may be applied instead of the mirror polishing finish. On the other hand, the bonding surface 13b of the Nd: YAG crystal 13 and the bonding surface 14b of the resonator mirror 14 to the mirror mounting surfaces 21a and 21b are also perpendicular to the optical axis so that the surface roughness is smaller than the oscillation wavelength. Had been finished.

Similarly, the bonding surface of the Nd: YAG crystal 13 is
After bringing 13b into close contact with the mirror mounting surface 21a of the holder 21,
By penetrating the adhesive through the gap between these two,
It is adhesively fixed to the holder 21. After allowing the adhesive to penetrate between the bonding surfaces, the adhesive was irradiated with short-wavelength visible light and cured.

After curing, the mirror mounting surface 21a and N
d: The thickness of each adhesive layer between the YAG crystal 13 and the mirror mounting surface 21b and the resonator mirror 14 was measured to be about 0.3 to 0.6 μm. This is the same as the 5μ
m or less. This adhesive has a volume curing shrinkage of 4 to 5% and a temperature of -25 ° C to 7%.
The change in thickness of each adhesive layer after performing the storage test at 0 ° C. was suppressed to 0.03 μm or less.

Therefore, the change in the resonator length (the distance between the end face 13a of the Nd: YAG crystal 13 and the mirror surface 14a of the resonator mirror 14) due to the change in the thickness of the adhesive layer is 0.1 mm.
It becomes 2 μm or less. This is the solid laser oscillation wavelength 94
Since it is 1/4 or less of 6 nm, fluctuation of the laser output and the longitudinal mode and generation of noise are surely prevented. In this example, the change in the oscillation wavelength was 0.01 nm or less.

As described above, Nd: YA is used as a solid laser crystal.
Although embodiments have been described using a G crystal and converting a solid state laser beam to a second harmonic, the invention is not limited to laser diode pumped solid state lasers using other solid state laser crystals, or In particular, the present invention can be similarly applied to a laser diode-pumped solid-state laser that does not perform wavelength conversion, and has the same effect.

Such a bonding method is not limited to a case where a resonator mirror in a solid-state laser is bonded to a mirror mounting surface, and generally includes optical components such as a light source, a lens, a mirror, a half mirror, a concave mirror, a convex mirror, and a diffraction grating. The present invention can be similarly applied to an optical device having such an optical device, which is applied when the optical device is bonded and fixed to a component mounting surface such as a holder for fixing them. By using the adhesive composition of the present invention, the adhesive layer is made thinner, and the change in the curing rate thereof and the change in the thickness of the adhesive layer caused by stress are reduced, thereby providing an effect of improving the durability. . The adhesive durability of the present invention can also be improved by applying and curing the adhesive composition of the present invention to an electronic device such as a solid-state imaging device (CCD) and its manufacture.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an embodiment of the present invention.

[Explanation of symbols]

 10 Laser beam (excitation light) 11 Semiconductor laser 12 Condensing lens 13 Nd: YAG crystal 13a Nd: YAG crystal coating surface 13b Nd: YAG crystal bonding surface 14 Resonator mirror 14a Resonator mirror mirror surface 14b Resonator mirror Bonding surface of 15 KN crystal 16 Etalon 18 Solid laser beam 19 Second harmonic 20, 21 Holder 21a, 21b Mirror mounting surface of holder 22 Reference plate 23 Heat sink 24 Peltier element

Claims (4)

[Claims] 1. An adhesive composition comprising an alicyclic epoxy compound having an epoxy group, a compound having an oxetanyl group, a catalytic amount of an onium salt photoinitiator, and a photosensitizer, is prepared from a plurality of optical components. Between the adherends having a thickness of 0.05 μm or more and 5 μm or less,
An optical device characterized by being cured with visible light having a wavelength of 390 to 500 nm. 2. The optical device according to claim 1, wherein the adhesive composition contains an imide acrylate or imide methacrylate represented by the following general formula (1). A— (CH ₂ —CH ₂ —O) _n —B (1) In the formula, A represents an imide group, n represents an integer of 1 or 2, and B represents an acryloyl group or a methacryloyl group. 3. The optical device according to claim 1, wherein the adherend is a metal member and an inorganic member that does not substantially transmit ultraviolet light and transmits visible light having a wavelength of 390 nm to 500 nm. 4. The optical device according to claim 1, wherein the compound having an oxetanyl group is represented by the following general formula (2). Embedded image In the formula (2), R ₁ represents a methyl group or an ethyl group. R
₂ represents a hydrocarbon group having 6 to 12 carbon atoms.