JP5624165B2 - Optical component bonding method and optical component - Google Patents

Description

The present invention relates to an adhesive how you and the optical components of the optical components.

As an adhesive method for optical parts, there are balsam, epoxy resin, methacrylic resin, polyester resin, ultraviolet curable resin, heat fusion and the like as an adhesive. However, these adhesives are all for visible light and cannot be used in the ultraviolet region below 250 nm.
On the other hand, in heat fusion, thermal strain remains in the optical material and cannot be used as an optical waveguide. For this reason, there is no method other than air contact for joining optical components. However, air contact is not possible with nonlinear optical crystals with high deliquescence. Furthermore, since the harmonic wave of the nonlinear optical crystal extends to the vacuum ultraviolet region, a transparent adhesive is desired even in the vacuum ultraviolet region.

Regarding bonding of optical materials, Patent Document 1 “Method of manufacturing optical element” describes a method of bonding two lenses, and after dropping a tetraisocyanate compound or a chlorosilane compound on a glass lens, it is rotated at a high speed. The solution is uniformly diffused, heated by an infrared heater from above the uniformly diffused solution to form a SiO ₂ film having a three-dimensional crosslinked structure by hydrolysis, and then slowly cooled to room temperature. Then, after applying an acrylate-based ultraviolet curable transparent resin adhesive on the SiO ₂ film, another glass lens is pressed on the SiO ₂ film, and ultraviolet rays are irradiated from above the glass lens to cure the resin. A complex is formed.
The SiO ₂ film formation by this method is based only on hydrolysis by overheating with infrared rays. In this method, a tetraisocyanate compound or chlorosilane compound is applied to the surface of one optical material, and then a flat surface that is completely vitrified by thermal hydrolysis is formed. An ultraviolet curable resin is applied to this surface, and the other optical material surface is applied. Joining is disclosed.
However, this is only a means for shaping the first optical system, not a joint with the second lens. An acrylate-based UV curable transparent resin adhesive is used for bonding between the two lenses and is cured by photoexcitation with UV rays of 350 to 380 nm, but the cured adhesive layer has almost no transmission of 250 nm or less, and a wavelength of 250 nm or less. It cannot be used in the area.
On the other hand, there is no strong adhesive other than heat fusion that does not require light transmission of 250 nm or less directly at the joint, but requires resistance to 300 ° C. or higher and does not generate gas in a vacuum. However, thermal fusion leaves thermal strain on the material surface. On the other hand, materials such as KDP are cracked inside and are not practical at temperatures above 100 ° C.

  Conventionally, in order to protect highly deliquescent nonlinear optical crystals such as KDP, KTP, BBO, and CLBO from moisture, there is no method other than forming a protective film by immersing the crystals in a Teflon-based solution and pulling them up. It was. Generally, there are vacuum deposition, ion plating, sputtering, CVD method, etc. as coating methods for optical parts, but these coating films are thin and most of them have a multilayer film structure. The film adhesion to was weak.

Regarding film thickness coating of optical materials, the present invention is a method of laminating transparent SiO ₂ at room temperature by irradiating ArF laser or Xe excimer lamp light in the presence of mixed gas of NF ₃ and O ₂ and Si wafer. These are disclosed in Patent Documents 2 and 3. However, even this method cannot produce a hard film that can be used at wavelengths shorter than 250 nm.

Regarding the formation of hard films, see ArF excimer laser in an oxygen atmosphere on a glass substrate coated with dimethylsiloxane silicone monomer (SiO (CH ₃ ) ₂ ) n (dimethylsiloxane silicone oil). Irradiate light to photodissociate methyl groups from siloxane bonds, and oxygen atoms in the ground state O (3P) generated by photoexcitation of oxygen bind to Si dangling bonds to form transparent SiO ₂ hard with a thickness of 2 μm. It is disclosed that a film is formed.
Further, claims 2 and 4 of Patent Document 4 by the inventor of the present application are coatings for nonlinear crystals such as LBO, BBO, CLBO, KDP, and KTP, and Patent Document 5 is a method for forming a densified film under gas pressure. Is disclosed. Non-Patent Document 2 states that a KDP nonlinear crystal coated with dimethylsiloxane silicone oil is subjected to a water resistance test in water to reveal that it is water resistant.

Regarding the method of forming an amorphous SiO ₂ film by irradiating an ultraviolet ray on a silicone oil in an oxygen atmosphere, the inventors of the present application describe Non-Patent Document 1 “Dimethylsiloxane silicone monomer (SiO (CH ₃ ) ₂ ) n (dimethylsiloxane silicone oil). ) Is irradiated with ArF excimer laser light in an oxygen atmosphere to photodissociate the methyl group from the siloxane bond, and the oxygen atom O (3P) in the ground state generated by photoexcitation of oxygen is Si. A transparent SiO ₂ hard film having a thickness of 2 μm was formed by bonding with danglin bonds ”. Patent Document 6 discloses that a nonlinear optical material is optically bonded with silicone oil in claim 2.

In addition to nonlinear optical crystals, oxides such as MgO, quartz, sapphire and rutile, chalcogenides such as ZnSe and CdS, phosphides such as GaP, GaAs, GaN, InP and InP, calcite, calcium fluoride, There are optical crystals such as halides such as magnesium fluoride, barium fluoride, LiF, NaCl, KCl, KBr, and KI.
Also, for laser components such as YAG laser, ruby laser, glass laser, ceramic laser, lens, optical window, mirror, prism, filter, polarizer, or optical components such as optical fiber, image intensifier, detector, plastic lens The development of anti-reflective coatings, hard coatings of reflective coatings, and laser resistant coatings is progressing. However, these coating films are vulnerable to moisture, and the dust adhering to the films absorbs laser light and changes to heat, which often leads to film destruction.

Japanese Patent Application No. 2-410824 (Japanese Patent Laid-Open No. 4-219349) Japanese Patent Application No. 3-260651 (Japanese Patent Laid-Open No. 5-102130) Japanese Patent Application No.6-222049 (Japanese Patent Laid-Open No. 8-088222) Japanese Patent Application No. 2003-298124 (Patent Publication 2005-70243) Japanese Patent Application No. 2005-035353 (Patent Publication 2006-219610) Japanese Patent Application No. 2003-298158 (Patent Publication 2005-70245) Japanese Patent Application No. 02-123760 (Japanese Patent Laid-Open No. 4-021540) Japanese Patent Application No. 2-250225 (Japanese Patent Laid-Open No. 4-130031) Japanese Patent Application No. 53-024972 (Japanese Patent Laid-Open No. 54-118196)

Masataka Murahara Plasticity and Processing (Journal of the Japan Society for Technology of Plasticity) Vol. 27, No. 307, 934-942 (1986) Murahara Masataka et al. Optics Letters, 30 (24), 3416-3418 (2005) Murahara Masataka Ceramics, 41 (6), 440-443 (2006) Shin-Etsu Chemical Co., Ltd. Technical data KF96 silicone oil performance test results (2003) Masataka Murahara Optics (Applied Physics Society), 20 (8), 30-35 (1991)

Non-linear optical crystals and chloride crystals have strong deliquescence, so there is no other way to prevent moisture adsorption, except that the crystals are always heated or dipped with a device in a Teflon solution. There were no attempts to use it underwater.
However, the input of high-density laser light is indispensable for developing a nonlinear phenomenon, and thermal destruction occurs when the intensity of the laser light is high. Accordingly, one of the problems to be solved by the present invention is to operate the nonlinear optical element in the cooling water in order to prevent thermal destruction.

  Reflects on optical elements such as laser elements such as YAG laser, ruby laser, glass laser, ceramic laser, lens, optical window, mirror, prism, filter, polarizer, or optical fiber, image intensifier, detector, plastic lens Although a hard coating film of a prevention film, a reflection film, and a laser resistant film are deposited, these coating films are vulnerable to moisture and inferior in laser resistance. This is because the deposited film is extremely thin, and the dust adhering to the film absorbs the laser beam, and the film is destroyed by the high temperature generated when it changes to heat. It is a problem to be solved by the present invention to impart laser resistance to the surfaces of these optical components.

A coating is suitable for protecting the nonlinear optical crystal from moisture, but it took too much time to coat the end faces of the device one by one. Therefore, in the present invention, a nonlinear optical crystal and a fluoride crystal or quartz glass are photochemically bonded with an organic silicone oil, and then changed to SiO ₂ that is an inorganic material by photooxidation. Another object of the present invention is to provide a nonlinear optical element having high strength and heat resistance.

  As a result of diligent research to achieve the above object, the present inventor has found that a nonlinear optical crystal after optical polishing, an optical crystal, a laser element, a lens, an optical window, a mirror, a prism, a filter, a polarizer, an optical fiber, an image intensity, Quartz glass, crown glass, flint glass, white plate glass, BK-7 (registered trademark), Tempax (registered trademark), Pyrex (registered trademark) polished to flat or spherical surfaces with optical components such as fire, detector, and plastic lens Silicone oil, which is an organic material, at the interface between optical glass such as Fluorine and Neoceram (registered trademark) and thin crystals such as calcium fluoride, magnesium fluoride, barium fluoride, LiF, NaCl, KCl, KBr, and KI Can be used even at wavelengths below 250 nm, and can be used for hardness, water resistance or moisture resistance. As the protective wall, and the bonding strength was found to withstand the use as a strong optical element heat resistance. In order to achieve this, the methods disclosed in Patent Document 6 and Non-Patent Document 3 by the inventors of the present application are used.

  In general, when silicone oil is applied to the surface of a substance, it is said that a release action is exhibited, and other substances are prevented from sticking, and at the same time, the stability against thermal oxidation is very excellent. However, when this silicone oil is irradiated with vacuum ultraviolet light, it can work photochemically as an adhesive. Utilizing this photochemical property is the aim of the present invention.

Non-patent by the inventors of the present application that the organic silicone oil is bonded to quartz by ultraviolet irradiation, and that the organic silicone oil itself is changed to quartz having a siloxane bond that is an inorganic glass by ultraviolet irradiation in the presence of an oxidizing agent. Reference 1 states that “A glass substrate coated with dimethylsiloxane silicone monomer (SiO (CH ₃ ) ₂ ) n (dimethylsiloxane silicone oil) is irradiated with ArF excimer laser light in an oxygen atmosphere to light the methyl group from the siloxane bond. The oxygen atom O (3P) in the ground state generated by dissociation and photoexcitation of oxygen was bonded to the Si dangling bond to form a transparent SiO ₂ hard film having a thickness of 2 μm ”.

According to Non-Patent Document 4, many types of representative silicone oil KF96 (Shin-Etsu Chemical Co., Ltd.) are commercially available from low viscosity 1 cs to high viscosity 1 million cs depending on the viscosity. This viscosity means a molecular weight, and the viscosity is equivalent to 200 to 100,000 when expressed in terms of molecular weight. In the present invention, these silicone oils having different molecular weights are used to polish polished optical component surfaces and halide crystals or quartz glass, crown glass, flint glass, white plate glass, BK-7 (registered trademark), Tempax (registered trademark). When the Xe ₂ excimer lamp light having a wavelength of 172 nm is irradiated between the optical glasses such as Pyrex (registered trademark) and Neoceram (registered trademark), the adhesive strength increases as the molecular weight of the silicone oil increases.

  According to Non-Patent Document 4, silicone oil generally contains 200 ppm of water inside and outside, and can dissolve air, oxygen, carbon dioxide gas, ozone, and the like. Thermally stable up to 150 ° C, thermal oxidation starts when the temperature exceeds 200 ° C and combustion begins at 450 ° C. Furthermore, the viscosity of silicone oil is lowered by heating, and the molecular weight is reduced.

The adhesion of the present invention is to photo-oxidize the organic silicone oil and change it to inorganic glass. For this reason, an oxygen source is required in the photoreaction process. The oxygen source is oxygen adsorbed on the sample surface, oxygen mixed in the silicone oil, water or carbon dioxide, air or oxygen supplied during the reaction, carbon dioxide gas or ozone. Therefore, the sample surface is previously subjected to plasma treatment or ultraviolet treatment in an oxygen atmosphere to increase the oxygen atom density on the sample surface. This treatment greatly affects the improvement of the ultraviolet transmittance after bonding. On the other hand, since silicone oil can dissolve air, oxygen, carbon dioxide gas, etc., in order not to lower the viscosity of the silicone oil, the silicone oil should be heated at room temperature, and when the viscosity should be lowered, it should be heated at 200 ° C or lower. After vacuum degassing, oxygen, ozone, etc. are dissolved again to promote the SiO ₂ formation of the adhesive layer.
However, when these oxidizing agents are excessive, the adhesive layer may become cloudy. The transmittance below 250 nm is somewhat reduced, but there is no white turbidity, and when maintaining transparency from visible light to near-ultraviolet region, reduce the viscosity by reducing the viscosity of the silicone oil at room temperature. Is heated at 200 ° C. or lower, vacuum degassed, and silicone oil from which contaminants such as oxygen, carbon dioxide, and water are excluded is applied to the surfaces to be joined.
However, in this case, the photochemical reaction is unlikely to occur because ultraviolet rays having a wavelength of 300 nm to 150 nm, which are the oxidants of the photochemical reaction, inhibit entry into the adhesive layer. For this reason, it is necessary to make the adhesive layer very thin and to increase the amount of incident ultraviolet rays.

In general, in a large area or uniform joining, uniformity and thinness of the thickness of the adhesive layer are required. For this reason, an ultra-low viscosity UV curable adhesive of 8 cps has been developed compared to the conventional 10 cps. However, the viscosity showing the strongest adhesive strength with silicone oil is about 10,000 cs, but the viscosity may be low because there is no need for high-strength adhesion in the adhesive instead of the coating. Therefore, in order to reduce the thickness of the adhesive layer and improve the uniformity, the surfaces of the materials to be joined are superposed in a high temperature atmosphere, and the gas is pressurized from 0 to 30 kg / cm ² from the pressure side, The bonded portion is depressurized and loaded with the differential pressure.
Here, in order to make the adhesive layer transparent, have high adhesive strength, have no adhesive stress distortion, and have a uniform thickness, both the surfaces to be bonded are cleaned and oxygen is adsorbed. It is desirable to perform cleaning processing such as plasma cleaning, ultraviolet cleaning in an oxidizing gas atmosphere, cleaning by direct injection of a cooling gas such as CO2 snow or ozone snow, or oxygen ion implantation.
In order to apply a uniform load to the adhesive layer, it is desirable to reduce the pressure in the inner pressure chamber and adjust the pressure difference between the outer pressure chambers, and the oxidant gas introduced into the inner pressure chamber is diluted with nitrogen or an inert gas. Instead of a mixed gas, dry, pure O2 gas, O3 gas, CO2 gas, etc. are introduced under reduced pressure. If a uniform load can be obtained, mechanical pressurization without the external pressure chamber may be used.

  CLON, BBO, LBO, BIBO, CBO, KDP, DKDP, KTP, KLN, KBBF, SBBO, and other non-linear crystals such as the excitation laser light incident surface and the harmonic output surface are both optically polished and then filled with silicone oil. In a state where the fluoride crystal or quartz glass thin plate is pressed and adhered with high pressure gas or machine, vacuum ultraviolet light such as Xe2 excimer lamp is incident and bonded from both or one of the fluoride crystal or quartz glass plate side.

When the fundamental wave of high-power laser light is incident on the nonlinear optical crystal surface, the tensile stress between the nonlinear crystal plane and the fluoride crystal or quartz glass interface, that is, the amorphous glass adhesive layer formed by photo-oxidation and the nonlinear optical crystal surface As a result, distortion may occur in the crystal plane. In order to avoid this, the excitation laser light incident surface and the harmonic wave emission surface sandwiched between a thin plate such as a fluoride crystal plate or a quartz glass plate and the nonlinear crystal surface are not bonded, leaving silicone oil and surrounding them. It is good to glue.
For this reason, with the quartz glass plate pressed and adhered to the crystal surface via silicone oil, the laser light incident surface and the light exit surface are covered with a mask, and the entire crystal surface is covered with ultraviolet rays such as an Xe2 excimer lamp. When irradiated, only the exposed part can be bonded, and the unexposed part is restrained with silicone oil, and only its periphery can be bonded. In this case, however, it should be noted that if the incident laser beam is too strong, the silicone oil is altered and solidified by heat, so that it cannot be used for a strong laser.

  In the nonlinear optical crystal, the laser beam incident surface and the harmonic output surface may be optically polished. For this reason, the periphery of the nonlinear optical crystal sandwiched between the fluoride crystal or the quartz glass plate as the optical surface is covered with an amorphous glass coating layer obtained by photo-oxidizing silicone oil, or the four surrounding surfaces are bonded with quartz glass. Yes, but not necessarily. As a simple method, it can be shielded from moisture and water by a silicon oxide film formed by ultraviolet irradiation in an oxygen atmosphere after application of pitch, a hydrophilic adhesive or silicone rubber.

A nonlinear optical crystal is placed in a cylindrical or rectangular tube-shaped container having one or a plurality of small holes on the side of a cylinder having the same length as that of the nonlinear optical crystal, and both ends of the cylinder are irradiated with and emitted from the laser beam. Both of the polished surfaces are photo-bonded under pressure with a thin plate of fluoride crystal or quartz glass through silicone oil, and then the nonlinear optical crystal inside the cylinder is dried in air or vacuum or one small hole on the side of the cylinder After flowing helium gas through the other small hole and heating it between 100 and 300 ° C, or by heating only with one small hole, the helium gas is enclosed and heated, and then evacuated to remove moisture inside the nonlinear optical crystal. After that, silicone oil or silicone resin is filled into the gap between the inside of the cylinder and the nonlinear optical crystal through a small hole on the side surface of the cylinder.
The method disclosed in Patent Documents 7 and 8 and Non-Patent Document 5 by the present inventors is used as a method of removing the moisture inside the substance by flowing helium gas in this high temperature atmosphere.
Here, a silicone oil that has been vacuum degassed and dehydrated in an atmosphere of 100 ° C. or higher is used. The reason why silicone oil is sealed in the cylinder is that the silicone oil absorbs the moisture inside the nonlinear optical crystal, and prevents the nonlinear optical crystal from coming into direct contact with the outside air even if it touches the outside air for some reason. is there. Therefore, it is necessary to completely seal the hole of the tube. For sealing the holes, it is desirable to use a quartz glass lid and photo-oxidation adhesion of silicone oil.
On the other hand, a silicone resin that does not generate gas during curing may be used and may be a room temperature curing type, but a high temperature curing method is desirable. Silicone resins such as RTV rubber are relatively elastic and are convenient for softly fixing the nonlinear optical crystal in the cylindrical container. However, since silicone resin is breathable, it is necessary to completely seal the hole in the cylinder. For sealing the holes, it is desirable to use a quartz glass lid and photo-oxidation adhesion of silicone oil.
In particular, when silicone oil or silicone resin is filled from a small hole into the gap between the inside of the cylinder and the nonlinear optical crystal, bubbles are restrained in the silicone oil or silicone resin when the inside of the cylinder is insufficiently deaerated. For this reason, it is desirable to avoid silicone oil or silicone resin press-fitting and to let it flow naturally with the inside of the cylinder being evacuated.
Since the nonlinear optical crystal element manufactured in this way does not allow moisture to enter the crystal, it can be used anywhere, and when the element is cooled, it can be cooled with water, air, or a Peltier refrigeration element. I can do it. As a method of electronically cooling an optical element that requires heat absorption with a Peltier refrigeration element, the method disclosed in Patent Document 9 by the present inventors is used.

It is also possible to float the nonlinear optical crystal in silicone oil without optically bonding the nonlinear optical crystal whose both the laser incident surface and the exit surface are optically polished with a thin plate such as a fluoride crystal or quartz glass. Therefore, the cylinder is placed in a cylinder or a rectangular tube container having a small hole on the side of the cylinder that is the same as or slightly longer than the nonlinear optical crystal, and only the both end faces of the cylinder are irradiated with a thin plate such as a fluoride crystal or quartz glass. Adhesive creates a nonlinear optical crystal storage container, and fills the gap between the inside of the cylinder and the nonlinear optical crystal with silicone oil from a small hole.
However, in this case, there is a methyl group in silicone oil that has not been photo-oxidized and vitrified, so in the case of strong laser input, it is deformed by the heat absorbed by the silicone oil, producing a fine glassy substance, When incident laser light is scattered and the temperature rises further, carbon of the methyl group is liberated and the entrance of incident light is inhibited. For this reason, this method is not suitable for a wavelength converter for a high-power laser.

Laser light is efficiently incident on optical components such as nonlinear optical crystals, optical crystals, laser elements, lenses, optical windows, mirrors, prisms, filters, polarizers, or optical fibers, image intensifiers, detectors, plastic lenses, In order to prevent the output harmonics from being reflected again into the crystal, it is desirable to deposit an antireflection film.
Generally, vacuum deposition may be performed on the surface of a thin plate that has been bonded. However, a reflection film or an optical film such as an antireflection film, metal, multilayer film, or interference filter may be applied to the surface of the optical component before bonding. .
However, the transmission wavelength range of calcium fluoride is 130 to 12000 nm and the refractive index is 1.4888 at 1000 nm, and the transmission wavelength range of magnesium fluoride is 110 to 9000 nm and the refractive index is 1.3778 at 1000 nm and 1.43975 at 178 nm. Both have low refractive index, especially magnesium fluoride can be used as an anti-reflection optical component in air, and calcium fluoride can be used as an optical component for anti-reflection in water.

To mass-produce nonlinear optical crystal elements for generating harmonics, after polishing the laser light incident surface and exit surface of a large crystal, both surfaces are made of thin plate such as large area halide crystal or quartz glass plate via silicone oil. Adhere light.
After bonding, the strip-shaped element is cut out with a diamond cutter in silicone oil, and the cut surface is further optically bonded to quartz glass via silicone oil, and then divided into a plurality of elements again with a diamond cutter in silicone oil. Thereafter, these elements are heated in dry air, in a vacuum, or in a helium gas atmosphere at 100 to 300 ° C., and then the two surfaces where the nonlinear crystals are exposed are optically bonded with quartz glass or optical glass to form an optical crystal. Shut off the entire surface from the atmosphere.
The non-linear optical crystal is cut with a diamond cutter using silicone oil as a cutting oil, thereby preventing the non-linear optical crystal from touching water or air during cutting.

  According to the present invention, an optical component and a thin plate such as a halide crystal or quartz glass are photochemically bonded using silicone oil as an adhesive, and an optical component having excellent ultraviolet light transmittance and resistance to moisture and moisture is obtained. The production and the nonlinear optical element for generating a harmonic wave can be mass-produced.

Nonlinear optical crystal bonding method and device fabrication procedure diagram Method for forming water-resistant protection of remaining 4 surfaces of CLBO nonlinear optical crystal with 2 surfaces bonded by fluoride crystal thin plate Nonlinear optical crystal bonding method and element fabrication procedure diagram to leave silicone oil around the optical axis Working gas pressure exposure equipment schematic Schematic diagram of a working gas pressurizing exposure apparatus with an internal pressure chamber in the external pressure chamber Schematic diagram of mechanical pressure exposure equipment Explanation for mass production of elements after batch bonding of nonlinear optical crystals for harmonic generation Explanatory drawing for mass production of elements after double-sided bonding of nonlinear optical crystals for generating harmonics after batch bonding and cutting into strip-shaped elements Schematic of a fluoride crystal plate bonded to a high-power laser mirror Schematic diagram of a laser resonator in which a fluoride crystal thin plate is optically bonded to the reflective film deposited on the resonator part of a solid laser rod, and an amorphous glass film is evaporated or a quartz glass plate is bonded to the excitation light incident part Schematic diagram of disk type laser amplifier Schematic of nonlinear optical crystal stored in a cylindrical container

The feature of the present invention is that, in the joining of optical components and thin plates such as halide crystals and optical glass, a silicone oil having a molecular weight of 200 to 120,000 is changed to SiO ₂ that is an inorganic material by photo-oxidation, so that the wavelength is 250 nm or less. However, it is to form an optical component that can be used and has high bonding strength.

Therefore, in the present invention, between a nonlinear crystal such as CLBO, BBO, LBO, KDP, DKDP, KTP, KLN, KBBF, and SBBO and a thin plate such as a fluoride crystal such as magnesium fluoride and calcium fluoride or a quartz glass. Apply silicone oil with a molecular weight between 200 and 120,000, and pressurize with mechanical pressure such as hydraulic pressure or water pressure, or dilute nitrogen gas, carbon dioxide gas, helium, air, oxygen, or oxygen or ozone gas with nitrogen gas or helium. Pressurize in the range of 0 to 30 kg / cm ² by pressurizing atmospheric gas such as mixed gas, Xe ₂ excimer lamp light, ArF excimer laser light, KrF excimer laser light, XeCl laser light, F ₂ laser light, harmonic laser light by nonlinear optical element, KrCl excimer lamp light, XeCl excimer lamp light, Hg lamp light, Hg-Xe lamp light, deuterium Surface bonding is performed photochemically by irradiating ultraviolet light having a wavelength of 300 nm to 150 nm obtained by lamp light, halogen lamp light, gas arc, corona or silent discharge in an oxidizing gas atmosphere.

In order to perform strong adhesion of silicone oil in a room temperature atmosphere, a molecular weight of 30,000 to 120,000 is required, and among these, 60,000 inside and outside has the highest adhesive strength. Therefore, in order to satisfy the uniformity and thinness of the thickness of the adhesive layer, the surfaces of the materials to be joined are superposed in a high temperature atmosphere and pressed in the range of 0 to 30 kg / cm ² .
Xe2 excimer lamp light, ArF excimer laser light, F2 laser light, harmonic laser light by nonlinear optical element, KrCl excimer lamp light, Hg lamp light, Hg-Xe lamp light, deuterium lamp light, halogen UV light having a wavelength of 300 nm to 150 nm obtained by lamp light or gas arc, corona or silent discharge is incident.
In addition, if methylphenyl silicone oil containing a small amount of hydrogen peroxide is used as the oxidizing agent, the absorption band peculiar to the phenyl group is around 250 nm, so KrF excimer laser, KrCl excimer lamp light, or XeCl excimer lamp light is used as excitation light. Etc. can be used.
When the oxygen in these silicone oils is excited by ultraviolet rays, some of them are used as carbon abstraction atoms, and the products are diffused out of the reaction system as CO ₂ gas. Other remaining active oxygen atoms are substituted after the removal of the methyl group, forming SiO ₂ and vitrified by sequential reaction.

  Prior to photobonding with silicone oil, plasma or ultraviolet light is applied to the surface to be bonded in an oxidizing gas atmosphere such as argon, xenon, or inert gas such as helium with air, oxygen, ozone, or trace amounts of oxygen. When the silicone oil is applied in a state where the surface to be bonded of the glass material is excessive in oxygen, and then irradiated with ultraviolet rays, the oxidation reaction of the silicone oil is carried out efficiently, and it is transparent in the ultraviolet region and has strong adhesive strength. Is obtained.

  Silicone oil is degassed under reduced pressure to remove contaminants such as large amounts of oxygen, carbon dioxide, and water, and then silicone oil with an appropriate amount of oxygen, ozone, carbon dioxide, water vapor, or other oxidizing agent added is used as an adhesive. If used, the photoreaction can be completed without an oxidant atmosphere. If silicone oil is heated and degassed in a state where the viscosity is lowered, more effective adhesion can be achieved.

  If silicone oil is applied to the material to be adhered and ultraviolet irradiation is performed while applying pressure in a carbon dioxide atmosphere, the polymerization is remarkable and strong adhesion can be achieved in a short time. More effective adhesion can be achieved by using degassed silicone oil as an adhesive.

A plastic or rubber bag with a synthetic quartz glass window or a container such as an envelope or the like, in contact with both quartz glasses coated with the silicone oil, isolated with O-ring and quartz glass while irradiating the bonded interface with ultraviolet rays By exhausting air or oxygen in the bonded portion and the light irradiation portion to a low pressure, photochemical bonding can be performed while uniformly applying a differential pressure between the atmospheric pressure and the internal pressure of the container to the joint portion of the material.
When the pressure is controlled by gas, a container such as a plastic film having a synthetic quartz glass window or a rubber envelope may be provided with a structure that can freely expand and contract such as a bellows or an O-ring.

In the case of photoadhesion with a uniform pressure mechanism, the reaction vessel is covered with an outer box having a fluoride crystal or quartz glass window, and this outer box is inert such as nitrogen gas, argon gas, xenon, carbon dioxide or helium gas. When pressurized with gas, a uniform load can be applied to the joint of the optical component. In this case, an internal pressure chamber is located in the external pressure chamber, the internal pressure chamber and the external pressure chamber are blocked by two ultraviolet incident windows, and an O-ring or bellows is provided between the ultraviolet incident window and the internal pressure chamber. Add.
As a result, the internal pressure gas and the external pressure gas are blocked, and the pressure in the external pressure chamber can be evenly transmitted to the internal pressure chamber. The thin plate with silicone oil sandwiched between one or both sides of the optical component is inserted between the two ultraviolet incident window plates, and at least one of the two ultraviolet incident window plates is made of quartz glass or a fluoride crystal plate.
When the ultraviolet transmittance of the optical component is high, the ultraviolet incident window may be provided at one location. This is because the vacuum ultraviolet light incident from one incident surface repeats internal reflection in the optical component, so if the fluoride crystal or optical glass plate is in close contact with the remaining surface via silicone oil, it can be Two or more spots can be bonded by irradiation. Here, the internal pressure chamber is provided with a cock capable of exchanging oxidant gases such as diluted oxygen, ozone, carbon dioxide, and water vapor, so that the photo-oxidation conditions are selected and the optical surface can be bonded in a short time.

  The reaction vessel with a quartz glass window is separated into two chambers with rubber plates. One synthetic quartz glass window is a sample chamber, the other is a mechanical pressurization chamber using hydraulic pressure or water pressure, and the sample chamber is heated with a vacuum exhaust valve. A heater is provided, and an adherend glass material coated with silicone oil is brought into contact with the quartz glass window side of the sample chamber, and UV irradiation is performed while applying mechanical pressure through a rubber plate to perform photoadhesion. After removing contaminants such as oxygen, carbon dioxide, and water in the silicone oil applied to the surface of the glass to be bonded with the vacuum exhaust valve provided in the sample chamber, oxygen, carbon dioxide, ozone, etc. are sealed at low pressure. , The adhesion effect can be enhanced. Furthermore, if the viscosity of the silicone oil is lowered by heating a film heater attached on a rubber plate, the adhesive layer can be made extremely thin.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 illustrates a method for bonding a nonlinear optical crystal and a device manufacturing procedure according to the present invention. The CLBO nonlinear optical crystal 1 whose two surfaces are optically polished is covered with a fluoride crystal thin plate 3 such as calcium fluoride or magnesium fluoride via a silicone oil 2, pressurized 4, and then irradiated with vacuum ultraviolet light 5. . By this light irradiation, the silicone oil 2 is transformed into an amorphous glass 6 to form a CLBO nonlinear optical crystal element 7 in which two glass surfaces are bonded.

  FIG. 2 is an explanatory diagram of a method for forming a water-resistant protection on the remaining four surfaces of a CLBO nonlinear optical crystal having two surfaces bonded with a fluoride crystal thin plate. A quartz glass plate 8 is bonded to the remaining four surfaces of the CLBO nonlinear optical crystal element 7 having two surfaces bonded by a fluoride crystal thin plate 3 by photooxidation adhesion of silicone oil, or a water-repellent adhesive 9 such as pitch is applied. Moisture and water are blocked by coating or by coating the silicone resin and irradiating with ultraviolet rays in the air to oxidize and vitrify the surface. The silicone resin coating alone has water resistance, but is inferior in moisture resistance because gas or water vapor enters.

FIG. 3 is a non-linear optical crystal bonding method for leaving silicone oil around the optical axis and a device manufacturing procedure diagram. The non-linear optical crystal 1 whose two surfaces are optically polished is covered with a quartz glass thin plate 10 (Supurasil (registered trademark) -310) through silicone-il 2, pressurized 4, and then subjected to vacuum ultraviolet light (Xe 2 through a shadow mask 11). Excimer lamp light irradiation) 5 is performed.
By this light irradiation, the unexposed part under the shadow mask 11 remains the silicone oil 2, but the part exposed by the vacuum ultraviolet light 5 is changed to amorphous glass 6, and the periphery is adhered and the periphery of the optical axis is not always present. A stress nonlinear optical element 12 is formed.

FIG. 4 is a schematic view of a working gas pressure exposure apparatus. A quartz glass thin plate 10 (Supurasil (registered trademark) -310) is covered with silicone oil 2 on the KDP nonlinear optical crystal 13 whose two surfaces are optically polished, and pressurized with gas. In the working gas pressurizing exposure apparatus 14, an ultraviolet light incident window 21 is passed through the exposure apparatus 14 while gas is pressurized to separate the gas pressurizing chamber 15 and the gas suction chamber 16 in order to generate a differential pressure due to the gas. In order to irradiate the vacuum ultraviolet ray 5, a quartz glass pressure plate 18 with an O-ring 17 around it is provided in order to prevent the gas from leaking, and an ultraviolet ray such as nitrogen gas, carbon dioxide gas, and helium from the gas input valve 19. The permeated gas is sealed, and first, the gas suction / disposal valve 20 is gradually depressurized while sealing the gas, such as air, oxygen, or a mixed gas pressurizing gas obtained by diluting oxygen or ozone gas with nitrogen gas or helium. A differential pressure is applied in the range of 0 to 30 kg / cm ² , and Xe2 excimer lamp light irradiation is performed through the vacuum ultraviolet ray incident window 21 while maintaining the differential pressure. By this light irradiation, the silicone oil 2 is transformed into amorphous glass, and the two quartz glass thin plates 10 are bonded.

FIG. 5 is a schematic view of a working gas pressurizing exposure apparatus having an internal pressure chamber in an external pressure chamber. The CLBO nonlinear optical crystal 1 whose two surfaces are optically polished is covered with a fluoride crystal thin plate 3 such as magnesium fluoride or calcium fluoride via a silicone oil 2 and pressurized with gas. A reaction vessel 22 having a uniform pressurization mechanism is covered with an external pressure chamber (outer box) 23 having a fluoride crystal or quartz glass window, and this external pressure chamber 23 is not filled with nitrogen gas, argon gas, xenon, carbon dioxide or helium gas. When pressurized with active gas, a uniform load can be applied to the joint of the optical component.
In this case, the internal pressure chamber 24 is located in the external pressure chamber 23, and the internal pressure chamber 24 and the external pressure chamber 23 are blocked by two ultraviolet incident windows / pressurizing plates 25 such as fluoride crystals or quartz glass. An O-ring 17 or a bellows is attached between the window / pressure plate 25 and the inside of the internal pressure chamber. As a result, the internal pressure gas and the external pressure gas are blocked, and the pressure in the external pressure chamber 23 can be evenly transmitted to the internal pressure chamber 24. Inserted between these two ultraviolet light incident window plates 25 is an optical component or a fluoride crystal thin plate 3 such as quartz glass or magnesium fluoride or calcium fluoride with a silicone oil 2 sandwiched on one or both sides of the CLBO nonlinear crystal 1. At least one of the two ultraviolet incident windows / pressure plates 25 is made of quartz glass or a fluoride crystal plate.
When the ultraviolet transmittance of the optical component is high, the ultraviolet incident window may be provided at one location. This is because the vacuum ultraviolet light incident from one incident surface repeats internal reflection in the optical component, so if the fluoride crystal or optical glass plate is in close contact with the remaining surface via silicone oil, it can be Two or more spots can be bonded by irradiation. Here, the internal pressure chamber 24 is provided with a cock 20 that can exchange oxidizing gases such as diluted oxygen, ozone, carbon dioxide, and water vapor. From the gas input valve 19 provided in the external pressure chamber 23, nitrogen gas, carbon dioxide gas, helium, etc. The high-pressure pressurization is performed by enclosing the UV-transmitting gas.
Here, in order to allow a uniform load on the adherend in the internal pressure chamber 24 in the range of 0 to 30 kg / cm ² , the ultraviolet incident window / pressurizing plate 25 between the internal pressure chamber 24 and the external pressure chamber 23 is The screwed holding frame 26 is not fixed through the O-ring 17 and is fixed. Thereby, an external pressure higher than the initial pressure can be applied. Vacuum ultraviolet light for photobonding is incident on the external pressure chamber 23. In order to generate a differential pressure due to the gas in the working gas pressurizing exposure apparatus 14, the gas pressurizing chamber 15 and the gas suction chamber 16 are separated. Thereby, it is possible to irradiate ultraviolet rays while applying gas pressure.
Here, in order to prevent gas from leaking, a quartz glass pressure plate 18 having an O-ring 17 around it is provided. First, air, oxygen, or oxygen or ozone gas is introduced into the gas suction / disposal valve 20 with nitrogen gas or helium. The pressure is gradually reduced while enclosing a gas such as pressurized mixed gas diluted by the pressure, and the pressure difference is increased in the range of 0 to 30 kg / cm ² , and the vacuum pressure is applied through the ultraviolet incident window 21 while maintaining the pressure difference. Light (Xe2 excimer lamp light) 5 irradiation is performed. By this light irradiation, the silicone oil 2 is transformed into amorphous glass and photoadhesion is performed. Here, the ultraviolet incident window 21 is fixed to the reaction vessel 22 having a uniform pressurizing mechanism by an attachment frame 27.

FIG. 6 is a schematic view of a mechanical pressure exposure apparatus. The nonlinear optical crystal 1 such as CLBO or KDP whose surfaces are optically polished is covered with a quartz glass thin plate 10 via a silicone oil 2, and pressure is applied by a mechanical pressure exposure device 28. The pressure is adjusted by uniformly tightening the bolt 29 with the nut 30. Pressurization is performed in the range of 0 to 30 kg / cm ² , and irradiation of vacuum ultraviolet light (Xe2 excimer lamp light) 5 is performed through an ultraviolet incident window 21 as a quartz glass pressure plate while maintaining the pressure.
By this light irradiation, the silicone oil 2 is transformed into amorphous glass and photoadhesion is performed. Here, the bonding portion has a structure of the internal pressure chamber 24, and the internal pressure chamber 24 is blocked from the outside air by the O-ring 17. The internal pressure chamber 24 is provided with a cock 20 that can exchange oxidizing gases such as diluted oxygen, ozone, carbon dioxide, and water vapor.

  FIG. 7 is an explanatory diagram for mass production of elements after collectively bonding nonlinear optical crystals for generating harmonics. After the opposing surfaces of the large nonlinear optical crystal 1 such as CLBO or KDP are polished, both surfaces thereof are bonded with the fluoride crystal thin plate 3 or the quartz glass thin plate 10 via the silicone oil 2. After bonding, the substrate is cut by a diamond cutter cutting line 31 and divided into a plurality of nonlinear optical crystal elements 32. The nonlinear optical crystal element 32 (7), in which the two cut surfaces are bonded by a quartz glass window, the remaining four surfaces are made of water-repellent adhesive 9 such as a pitch, or the remaining four surfaces are fused by photooxidation bonding of silicone oil. It is cut off from moisture and water by pasting 8.

FIG. 8 is an explanatory diagram for mass-producing a double-sided element after bonding the two-sided non-linear optical crystal after it is bonded together and cut into a strip-shaped element. After the opposing surfaces of the large nonlinear optical crystal 1 such as CLBO or KDP are polished, both surfaces are bonded with the fluoride crystal thin plate 3 or the quartz glass thin plate 10 via the silicone oil 2. After bonding, the substrate is cut by a diamond cutter cutting line 31 to form a rectangular nonlinear optical element 33. The quartz glass plate 8 is optically bonded to the cut surface via silicone oil, and then divided into a plurality of nonlinear optical crystal elements 32. .
Next, these elements are heated in dry air, in a vacuum, or in a helium gas atmosphere at 100 to 300 ° C., and then the two surfaces where the nonlinear crystals are exposed are photobonded with the quartz glass plate 8 to nonlinear optics. The entire surface of the crystal element 32 is shielded from moisture, water, or air.

  FIG. 9 is a schematic view in which a fluoride crystal plate is bonded to a high-power laser mirror. The fluoride crystal thin plate 3 was photoadhered to the deposition surface of the reflective film 34 of the laser mirror substrate 35 on which the reflective film 34 was applied via the silicone oil 2. Thereby, it becomes a mirror satisfying water resistance, moisture resistance, high antireflection property and laser resistance.

FIG. 10 is a schematic diagram of a laser resonator in which a fluoride crystal thin plate is optically bonded to a reflective film deposited on a resonator portion of a solid laser rod, and an amorphous glass film is evaporated or a quartz glass plate is bonded to an excitation light incident portion. is there.
(A) is a cylindrical laser rod, (B) is a slab type laser rod. After coating the outer wall of the cylindrical solid laser rod with silicone oil, an amorphous glass film 37 is formed by irradiating excimer lamp light in an air atmosphere. This amorphous glass film 37 protects the laser rod from the high-speed cooling water of the laser rod, and since this protective film is transparent in the ultraviolet region, it can be photoexcited through the cooling water. In particular, when the laser rod is phosphoric acid, erosion by water can be prevented.
On the other hand, the fluoride crystal thin plate 3 is optically bonded to the light emitting surface side of the laser resonator of the cylindrical laser rod 36 of FIG. After photoadhering the fluoride crystal thin plate 3, a reflective film 34 is deposited to enhance laser resistance.
On the other hand, in the case of the (B) slab type laser rod 38, the quartz glass plate 8 is optically bonded to the incident surface and side surface of the laser excitation light via the silicone oil 2 to protect the laser rod from the high-speed cooling water, Moreover, since this protective film is transparent in the ultraviolet region, it can be photoexcited through cooling water.

  FIG. 11 is a schematic diagram of a disk type laser amplifier. The fluoride crystal thin plate 3 is photobonded to both surfaces of the disk type laser head 39 through the silicone oil 2 and is excited by excitation light 40 such as a semiconductor laser or a flash lamp to output laser light 41. Here, the fluoride crystal thin plate 3 has high hardness and protects the laser rod from the high-speed cooling water. Further, since this protective film is transparent in the ultraviolet region, it can be photoexcited through the cooling water.

FIG. 12 is a schematic view in which a nonlinear optical crystal is stored in a cylindrical container. The CLBO nonlinear optical crystal 1 is placed in a cylindrical container 42 having a small hole 44 on the side surface of the cylinder 42 having the same length as that of the nonlinear optical crystal 1, and both end faces of the cylinder 42 and both polished surfaces of the nonlinear optical crystal 1 are both included. After a thin plate such as fluoride crystal 3 or quartz glass 8 is photobonded with silicone oil in a pressurized state, helium gas is removed from dry air or vacuum or from one small hole on the side of the cylinder. After heating from 100 to 300 ° C. while exhausting from the other small hole, silicone oil 2 or silicone resin 43 is filled into the gap between the inside of the cylinder and the nonlinear optical crystal from the small hole 44 on the side surface of the cylinder.
The silicone oil to be injected here is one that has been vacuum degassed and dehydrated in a temperature atmosphere of 100 ° C. or higher and 200 ° C. or lower. Thereafter, the small hole 44 is closed by photooxidation adhesion of a quartz glass lid and silicone oil.

  According to the present invention, since the nonlinear optical crystal that has been used by using nerves for moisture can be used in the atmosphere or in cooling water, it can be provided for industrial use.

  According to the present invention, most optical such as optical crystal, laser element, lens, optical window, mirror, prism, filter, polarizer, or optical fiber, image intensifier, detector, plastic lens as well as nonlinear optical crystal. Since the parts have moisture resistance, water resistance, or strong laser resistance, they are not limited to the use environment as compared with conventional coatings, so that they can be greatly expected for industrial use.

(A) Cylindrical laser rod (B) Slab type laser rod 1 Nonlinear optical crystal (CLBO, KDP, BBO, etc.) or optical component 2 Silicone oil 3 Fluoride crystal thin plate (Calcium fluoride, Magnesium fluoride, etc.)
4 Pressurization 5 Vacuum ultraviolet light (Xe2 excimer lamp)
6 Amorphous glass (adhesive layer)
7 Nonlinear optical crystal bonded with two thin plates such as fluoride crystal or quartz glass 8 Quartz glass plate 9 Hydrophilic adhesive such as silicone rubber and pitch 10 Quartz glass thin plate 11 Mask (for unexposed part)
DESCRIPTION OF SYMBOLS 12 Nonlinear optical element 13 KDP nonlinear optical crystal 14 Working gas pressurization exposure apparatus 15 Gas pressurization chamber 16 Gas suction chamber 17 O ring 18 Pressure plate made of quartz glass 19 Gas input valve 20 Gas suction / disposal valve 21 Vacuum ultraviolet incident window 22 Reaction vessel having uniform pressurization mechanism 23 External pressure chamber 24 Internal pressure chamber 25 UV incident window / pressurization plate 26 Screw holding frame 27 Mounting frame 28 Mechanical pressure exposure device 29 Bolt 30 Nut 31 Diamond cutter cutting line 32 Divided by diamond cutter Nonlinear optical element 33 Rectangular nonlinear optical element 34 Reflective film 35 Laser mirror substrate 36 Cylindrical laser rod 37 Amorphous glass film 38 Slab type laser rod 39 Disc type laser head 40 Excitation light 41 Laser light 42 Cylinder (Cylinder, Square cylinder) )
43 Silicone resin (RTV rubber)
44 Small hole (degassing, gas filling, silicone oil or silicone resin press fitting)

Claims (7)

At least one member of a mirror or a thin plate made of a fluoride crystal plate or quartz glass is transparent to ultraviolet rays,
In oxidizing gas atmosphere, sandwiching silicone oil between the mirror and the sheet,
Then, by optical adhesive incident ultraviolet ultraviolet transparent member side in a state of evenly pressurized consolidating wearing them by utilizing the differential pressure between the external pressure due to the oxidation gas, only in the air A method for optically bonding optical components, characterized in that an optical component that can be used even in cooling water is produced . At least one member of a laser element or a thin plate made of a fluoride crystal plate or quartz glass is transparent to ultraviolet rays,
In oxidizing gas atmosphere, sandwiching silicone oil between the the laser element sheet,
Then, by optical adhesive incident ultraviolet ultraviolet transparent member side in a state of evenly pressurized consolidating wearing them by utilizing the differential pressure between the external pressure due to the oxidation gas, only in the air A method for optically bonding optical components, characterized in that an optical component that can be used even in cooling water is produced . In an oxidizing gas atmosphere, silicone oil is sandwiched between a mirror and a thin plate made of a fluoride crystal plate or quartz glass, and these are uniformly press-contacted using the pressure difference between the pressure of the oxidizing gas and the external pressure. An optical component that is photo-adhered with ultraviolet rays incident thereon,
A mirror having a reflective film on the adhesive surface;
Wherein a thin plate that is bonded via the silicone oil to the mirror,
And have a optical component, characterized in that the can be used in the cooling water as well as the atmosphere. In an oxidizing gas atmosphere, silicone oil is sandwiched between a laser element and a thin plate made of a fluoride crystal plate or quartz glass, and these are uniformly press-fitted using the differential pressure between the pressure of the oxidizing gas and the external pressure. An optical component optically bonded by entering ultraviolet rays in a state where
A laser element having a reflective film on the adhesive surface;
Wherein a thin plate that is bonded via the silicone oil to the laser device,
And have a optical component, characterized in that the can be used in the cooling water as well as the atmosphere. The thin plate is a fluoride crystal plate,
The optical component according to claim 3 or 4, wherein a reflective film is deposited on a mirror or a laser element.   5. The optical component according to claim 4, wherein the laser element is a disk type laser head. The optical component according to claim 3 or 4, wherein the thin plate is made of quartz glass.

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