JP2010102272A - Method of producing optical element, and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing an optical element, by which an optical element having high light resistance, high dimensional accuracy and a high light transmittance are produced by bonding two optical components to each other with a bonding film interposed therebetween, and an optical element produced by the method of producing an optical element. <P>SOLUTION: The method of producing an optical element includes: a step (first step) of preparing a first optical component 2 and a second optical component 4 and forming a bonding film 3 on a surface of the first optical component 2 by plasma polymerization; a step (second step) of exposing an edge (ineffective area) 3b of the bonding film 3 to plasma to thereby allow the edge 3b to develop adhesiveness, and irradiating an effective diameter (effective area) 3a with ultraviolet rays to thereby make the effective area 3a inorganic; and a step (third step) of bonding the first optical component 2 and the second optical component 4 to each other with the bonding film 3 interposed therebetween to thereby obtain the objective multilayer optical element 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an optical element and an optical element.

Conventionally, when two members (substrates) are joined (adhered), a method of using an adhesive such as an epoxy adhesive, a urethane adhesive, or a silicone adhesive is often used.
The adhesive can exhibit adhesiveness regardless of the material of the member. For this reason, members composed of various materials can be bonded in various combinations.
For example, a wavelength plate is known as an optical element having a function of causing a phase difference in transmitted light. The wave plate is a laminate of two birefringent crystal substrates such as quartz, and the substrates are bonded using an adhesive.
In this way, when the substrates are bonded to each other using the adhesive, a liquid or paste adhesive is applied to the bonding surface, and the substrates are bonded to each other through the applied adhesive. Thereafter, the adhesive is cured by the action of heat or light to bond the substrates together.

However, in such an optical element with light transmission, the optical characteristics of the adhesive affect the overall optical characteristics. For this reason, for example, in order to increase the light transmittance of the optical element, it is preferable that the refractive index of the substrate and the refractive index of the adhesive are close to each other, but the refractive index of the adhesive is In many cases, it is uniquely determined according to the composition, and it is difficult to adjust to an arbitrary value according to the refractive index of the substrate. Even if the refractive index of the adhesive is adjusted to the refractive index of the substrate, the resin component constituting the adhesive deteriorates with long-term light irradiation, causing discoloration of the adhesive, change in refractive index, adhesive strength. There is a risk of lowering the level.
Therefore, in Patent Document 1, a bonding material is applied to a portion of the optical isolator element other than the opening (inner portion) that is a light transmission surface, and the polarizers are laminated through the bonding material. Are disclosed.

In an optical element such as an optical isolator element, in general, its light transmission surface is often divided into an effective area where light transmission should be ensured and an invalid area where light transmission is not necessarily required. Therefore, the optical characteristics of the optical element need only be ensured in the effective area, and the ineffective area can be used as an area for bonding the substrates together. In the optical isolator element described in Patent Document 1, a region corresponding to the invalid region is set at the edge of the polarizer.
However, in the optical isolator element described in Patent Document 1, an air layer corresponding to the thickness of the bonding material is formed between the polarizers, whereby the difference between the refractive index of the polarizer and the refractive index of the air layer. An optical loss called “Fresnel reflection loss” occurs. As a result, this optical loss has caused a decrease in the light transmittance of the optical isolator element.

Japanese Patent Laid-Open No. 10-333095

  An object of the present invention is to provide an optical element manufacturing method capable of manufacturing an optical element having high light resistance, high dimensional accuracy, and high light transmittance by bonding two optical components to each other via a bonding film, and the method. An object of the present invention is to provide an optical element manufactured by an optical element manufacturing method.

Such an object is achieved by the present invention described below.
The optical element manufacturing method of the present invention provides a first optical component and a second optical component capable of forming an optical element by bonding together via a bonding film, and is provided on the surface of the first optical component. A first step of forming the bonding film including a Si skeleton having a random atomic structure including a siloxane (Si-O) bond and a leaving group bonded to the Si skeleton by a plasma polymerization method;
By irradiating the effective optical region of the optical element with ultraviolet rays in the bonding film, most of the leaving groups present in the effective region are desorbed from the Si skeleton, and the effective region is While chemically stabilizing, by giving energy to an ineffective region other than the effective region of the bonding film, the leaving group present on the surface of the ineffective region is desorbed from the Si skeleton, A second step of developing adhesiveness;
And a third step of bonding the first optical component and the second optical component via the bonding film exhibiting adhesiveness to obtain the optical element.
Thereby, by bonding two optical components together via the bonding film, an optical element having high light resistance and dimensional accuracy and high light transmittance can be manufactured.

In the method for producing an optical element of the present invention, among the atoms obtained by removing H atoms from all atoms constituting the bonding film, the total of the Si atom content and the O atom content is 10 to 90 atomic%. It is preferable.
Thereby, in the bonding film, Si atoms and O atoms form a strong network, and the bonding film itself becomes strong. Further, such a bonding film exhibits particularly high bonding strength with respect to the first optical component and the second optical component.

In the method for manufacturing an optical element of the present invention, the abundance ratio of Si atoms and O atoms in the bonding film is preferably 3: 7 to 7: 3.
As a result, the stability of the bonding film is increased, and the first optical component and the second optical component can be bonded more firmly.
In the method for producing an optical element of the present invention, the crystallinity of the Si skeleton is preferably 45% or less.
As a result, the Si skeleton particularly includes a random atomic structure. And the joining film excellent in dimensional accuracy and adhesiveness is obtained.

In the method for manufacturing an optical element according to the present invention, it is preferable that the bonding film includes a Si—H bond.
Si-H bonds are thought to inhibit the regular formation of siloxane bonds. For this reason, the siloxane bond is formed so as to avoid the Si—H bond, and the regularity of the Si skeleton is lowered. In this way, according to the plasma polymerization method, the Si skeleton having a low crystallinity can be efficiently formed by including the Si—H bond in the bonding film.

In the method for producing an optical element of the present invention, when the peak intensity attributed to the siloxane bond is 1, the peak intensity attributed to the Si—H bond in the infrared absorption spectrum of the bonding film including the Si—H bond. Is preferably 0.001 to 0.2.
As a result, the atomic structure in the bonding film becomes relatively random. For this reason, the bonding film is particularly excellent in bonding strength, chemical resistance and dimensional accuracy.

In the method for producing an optical element of the present invention, the leaving group is an H atom, a B atom, a C atom, an N atom, an O atom, a P atom, an S atom and a halogen atom, or each of these atoms is the Si skeleton. It is preferably composed of at least one selected from the group consisting of atomic groups arranged so as to be bonded to each other.
These leaving groups are relatively excellent in binding / leaving selectivity by applying energy. For this reason, the leaving group which leaves | separates comparatively easily and uniformly by providing energy is obtained, and the adhesiveness of the bonding film can be further enhanced.

In the method for producing an optical element of the present invention, the leaving group is preferably an alkyl group.
Thereby, a bonding film excellent in weather resistance and chemical resistance can be obtained.
In the method for producing an optical element of the present invention, in the infrared absorption spectrum of the bonding film containing a methyl group as the leaving group, when the peak intensity attributed to the siloxane bond is 1, the peak intensity attributed to the methyl group Is preferably 0.05 to 0.45.
As a result, the content ratio of the methyl group is optimized, and a necessary and sufficient number of active hands are generated in the bonding film while preventing the methyl group from unnecessarily inhibiting the formation of the siloxane bond. Adhesiveness is sufficient. Further, the bonding film exhibits sufficient weather resistance and chemical resistance due to the methyl group.

In the method for producing an optical element of the present invention, it is preferable that the bonding film has an active hand after the leaving group existing at least near the surface thereof is detached from the Si skeleton.
Thereby, the bonding film can be firmly bonded to the second optical component based on chemical bonding.
In the method for producing an optical element of the present invention, the active hand is preferably a dangling bond or a hydroxyl group.
As a result, particularly strong bonding is possible with respect to the second optical component.

In the method for producing an optical element of the present invention, the bonding film is preferably composed of polyorganosiloxane as a main material.
As a result, a bonding film superior in adhesiveness can be obtained. In addition, this bonding film has excellent weather resistance and chemical resistance, and is effectively used for bonding optical components that are exposed to chemicals and the like for a long time.

In the method for producing an optical element of the present invention, it is preferable that the polyorganosiloxane is mainly composed of a polymer of octamethyltrisiloxane.
Thereby, a bonding film having particularly excellent adhesiveness can be obtained.
In the method for producing an optical element of the present invention, in the plasma polymerization method, the high-frequency power density when generating plasma is preferably 0.01 to 100 W / cm ² .
Accordingly, it is possible to reliably form a Si skeleton having a random atomic structure while preventing the plasma gas from being added to the source gas more than necessary due to the high frequency power density.

In the method for producing an optical element of the present invention, the average thickness of the bonding film is preferably 1 to 1000 nm.
Thereby, these can be joined more firmly, preventing that the dimensional accuracy of the optical element which joined the 1st optical component and the 2nd optical component falls remarkably.
In the method for producing an optical element of the present invention, the bonding film is preferably a solid having no fluidity.
Thereby, the dimensional accuracy of the obtained optical element becomes remarkably high compared with the past. In addition, stronger bonding can be achieved in a shorter time than in the past.

In the method for manufacturing an optical element of the present invention, it is preferable that the refractive index of the bonding film after the ultraviolet irradiation of the effective region is 1.35 to 1.6.
Such a refractive index region has a refractive index relatively close to that of quartz or quartz glass, and is therefore preferably used, for example, in manufacturing an optical element having a structure in which the optical path penetrates the bonding film. .
In the optical element manufacturing method of the present invention, it is preferable that the invalid area of the bonding film is set at an edge of the optical element.
In general, almost no light strikes the edge of the optical element, so that the bonding film hardly deteriorates or deteriorates due to light at the edge. For this reason, a decrease in adhesiveness due to alteration and deterioration of the bonding film is suppressed, and an optical element that can maintain high reliability over a long period of time is obtained. Further, even if light hits the edge of the bonding film and a problem such as discoloration occurs, such a problem does not affect the light passing through the effective region, thereby causing a decrease in the optical characteristics of the optical element. There is no.

In the method for manufacturing an optical element according to the aspect of the invention, it is preferable that in the bonding film after the second step, the effective region is formed using silicon oxide as a main material.
As a result, the effective area of the bonding film has excellent transparency and excellent properties such as heat resistance, light resistance, chemical resistance, and mechanical strength.
In the method for producing an optical element of the present invention, the wavelength of ultraviolet light in the second step is preferably 126 to 300 nm.
According to the ultraviolet ray having such a wavelength, the leaving group in the bonding film can be reliably removed.

In the method for manufacturing an optical element of the present invention, it is preferable that the cumulative amount of ultraviolet light in the second step is 1 J / cm ² or more.
Thereby, the effective area | region of a joining film | membrane can be mineralized reliably.
In the method for manufacturing an optical element of the present invention, in the second step, the atmosphere in which the bonding film is irradiated with ultraviolet rays is preferably a dry atmosphere.
As a result, it is possible to prevent water vapor in the atmosphere from adsorbing to the cuts of the chemical bonds that have been cut by the irradiation of ultraviolet rays, and to prevent unintended changes in the composition of the bonding film.

In the method for manufacturing an optical element of the present invention, in the second step, the atmosphere in which the bonding film is irradiated with ultraviolet rays is preferably an inert gas atmosphere or a reduced pressure atmosphere.
As a result, it is possible to prevent the bonding film from being oxidized and altered or deteriorated with the irradiation of the bonding film with ultraviolet rays.
In the method for manufacturing an optical element of the present invention, it is preferable that the first optical component and the second optical component are each made of quartz glass or quartz.
As a result, the difference in refractive index between the first optical component and the second optical component and the bonding film is reduced, and the obtained optical element has a sufficiently suppressed light loss, and thus has excellent light transmittance. An optical element is obtained.
In the method for producing an optical element of the present invention, the application of the energy is performed by a method of exposing the bonding film to plasma,
The plasma is preferably atmospheric pressure plasma.
Thereby, it is possible to prevent the bonding film from being damaged and to obtain a bonding film excellent in adhesiveness and optical performance.

In the method for manufacturing an optical element of the present invention, in the first step, a bonding film similar to the bonding film is formed on the surface of the second optical component,
In the second step, after irradiating the bonding films with ultraviolet rays, in the third step, the bonding films are brought into close contact with each other so that the first optical component and the second optical component are in close contact with each other. Is preferably bonded to obtain the optical element.
Thereby, a 1st optical component and a 2nd optical component can be joined more firmly.
The optical element of the present invention has two optical components, which are joined by the method for manufacturing an optical element of the present invention.
Thereby, an optical element with high optical performance is obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical element manufacturing method and an optical element according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
<Optical element manufacturing method>
The optical element manufacturing method of the present invention is a method of bonding two optical components (the first optical component 2 and the second optical component 4) via the bonding film 3. According to this method, the two optical components 2 and 4 can be firmly bonded with high dimensional accuracy. The bonding film 3 is formed by a plasma polymerization method, and includes a Si skeleton having a random atomic structure including a siloxane (Si—O) bond and a leaving group bonded to the Si skeleton. .

When the edge portion of such a bonding film 3 is exposed to plasma, the leaving group existing near the surface of the bonding film 3 is detached from the Si skeleton, and adhesiveness is developed. By utilizing this adhesiveness, the two optical components 2 and 4 can be firmly bonded at the edge portion even at low temperatures via the bonding film 3, and a highly reliable laminated optical element can be obtained.
On the other hand, when the region inside the edge of the bonding film 3 is irradiated with ultraviolet rays having a predetermined integrated light amount, most of the leaving groups in the inner region are detached, and substantially only the Si skeleton remains. Thereby, an inner side area | region will be comprised only with the inorganic component substantially, and will become the thing excellent in light resistance. As a result, the obtained laminated optical element 5 has stable optical characteristics over a long period of time.

<< First Embodiment >>
Next, a first embodiment of the optical element manufacturing method of the present invention will be described.
1 and 2 are views (longitudinal sectional views) for explaining a first embodiment of a method for producing an optical element of the present invention. In the following description, the upper side in FIGS. 1 and 2 is referred to as “upper” and the lower side is referred to as “lower”.

  In the optical element manufacturing method according to the present embodiment, the first optical component 2 and the second optical component 4 are prepared, and the bonding film 3 is formed on the surface of the first optical component 2 by plasma polymerization. And a step of exposing the edge (invalid region) 3b of the bonding film 3 to plasma and irradiating the effective diameter (effective region) 3a with ultraviolet rays (second step). And the step of joining the first optical component 2 and the second optical component 4 via the bonding film 3 to obtain the laminated optical element 5 (third step). Hereinafter, each process will be described sequentially.

[1] First, the first optical component 2 and the second optical component 4 are prepared.
These optical components 2 and 4 are capable of forming a laminated optical element 5 having optical transparency by being bonded to each other through a bonding film 3. A specific laminated optical element 5 will be exemplified later.
The constituent material of the first optical component 2 may be a light transmissive material, for example, a polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), or cyclic polyolefin. , Modified polyolefin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide (eg, nylon 6, nylon 46, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6-12, nylon 6-66), Polyimide, polyamideimide, polycarbonate (PC), poly- (4-methylpentene-1), ionomer, acrylic resin, acrylonitrile-butadiene-styrene copolymer (ABS resin), acrylonitrile-styrene copolymer (AS resin) , Butazier -Polyester such as styrene copolymer, polyoxymethylene, polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycyclohexane terephthalate (PCT), Polyether, Polyetherketone (PEK), Polyetheretherketone (PEEK), Polyetherimide, Polyacetal (POM), Polyphenylene oxide, Modified polyphenylene oxide, Polysulfone, Polyethersulfone, Polyphenylenesulfide, Polyarylate, Aromatic polyester (Liquid crystal polymer), polytetrafluoroethylene, polyvinylidene fluoride, other fluororesins, styrene, polyolefin, polysalt Various thermoplastic elastomers such as vinyl, polyurethane, polyester, polyamide, polybutadiene, trans polyisoprene, fluororubber, chlorinated polyethylene, epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester , Silicone resins, urethane resins, etc., or various resin materials such as copolymers, blends, polymer alloys, etc., soda glass, quartz glass, lead glass, potassium glass, borosilicate glass, non-alkali glass materials such as glass, quartz, calcite, _{sapphire, CaF 2, BaF 2, MgF} 2, LiF, KBr, KCl, NaCl, MgO, YVO 4, LiNbO 3 crystal materials of the like.

Among these, from the viewpoint of refractive index matching and adhesion (bondability) with the bonding film 3, silicon oxide-based materials such as quartz glass and quartz are preferably used. Since the silicon oxide-based material has excellent transparency and excellent properties such as heat resistance, light resistance, chemical resistance, and mechanical strength, the configuration of the first optical component 2 It is particularly suitable as a material.
On the other hand, the constituent material of the second optical component 4 may be appropriately selected from the constituent materials of the first optical component 2, and the constituent material of the first optical component 2 and the constituent material of the second optical component 4 are as follows. May be the same or different.
Further, the first optical component 2 and the second optical component 4 may be obtained by forming various optical thin films on the surfaces thereof.

Next, the bonding film 3 is formed on the surface of the first optical component 2 (first step). The bonding film 3 is located between the first optical component 2 and the second optical component 4 and bears the bonding therebetween.
As shown in FIGS. 3 and 4, the bonding film 3 includes a Si skeleton 301 including a siloxane (Si—O) bond 302 and a random atomic structure, and a leaving group 303 bonded to the Si skeleton 301. It is what you have.
The bonding film 3 will be described later in detail.

In addition, before forming the bonding film 3 in the region where the bonding film 3 of the first optical component 2 is to be formed, depending on the constituent material of the first optical component 2, the first optical component is previously formed. It is preferable to perform a surface treatment for improving the adhesion between the bonding film 2 and the bonding film 3.
Examples of the surface treatment include physical surface treatment such as sputtering treatment and blast treatment, plasma treatment using oxygen plasma, nitrogen plasma, etc., corona discharge treatment, etching treatment, electron beam irradiation treatment, ultraviolet irradiation treatment, ozone Examples include chemical surface treatment such as exposure treatment, or a combination of these. By performing such treatment, the region where the bonding film 3 of the first optical component 2 is to be formed can be cleaned and the region can be activated. Thereby, the bonding strength between the first optical component 2 and the bonding film 3 can be increased.

In addition, by using plasma treatment among these surface treatments, the surface of the first optical component 2 can be particularly optimized in order to form the bonding film 3.
In addition, when the 1st optical component 2 which performs surface treatment is comprised with the resin material (polymer material), especially a corona discharge process, a nitrogen plasma process, etc. are used suitably.
Further, depending on the constituent material of the first optical component 2, there is a material in which the bonding strength of the bonding film 3 is sufficiently high without performing the surface treatment as described above. Examples of the constituent material of the first optical component 2 that can obtain such an effect include materials mainly composed of various glass materials and various crystal materials as described above.

The surface of the first optical component 2 made of such a material is covered with an oxide film, and a relatively active hydroxyl group is bonded to the surface of the oxide film. Therefore, when the first optical component 2 made of such a material is used, the adhesion strength between the first optical component 2 and the bonding film 3 can be increased without performing the surface treatment as described above. it can.
In this case, the entire first optical component 2 may not be made of the material as described above, and at least the vicinity of the surface of the region where the bonding film 3 is to be formed is made of the material as described above. Just do it.

  On the other hand, the bonding strength between the first optical component 2 and the second optical component 4 is sufficiently high even if the second optical component 4 is not subjected to the surface treatment as described above depending on the constituent material. There is something to be. As the constituent material of the second optical component 4 capable of obtaining such effects, the same constituent materials as those of the first optical component 2 described above, that is, various glass materials, various crystal materials, and the like can be used. .

Further, in the case where the following group or substance is included in the region that is in close contact with the bonding film 3 of the second optical component 4, the first optical component 2 and the second optical component 2 can be used without performing the surface treatment as described above. The bonding strength with the optical component 4 can be sufficiently increased.
Examples of such groups and substances include functional groups such as hydroxyl groups, thiol groups, carboxyl groups, amino groups, nitro groups, and imidazole groups, radicals, ring-opened molecules, double bonds, and triple bonds. And at least one group or substance selected from the group consisting of a saturated bond, a halogen such as F, Cl, Br, and I, and a peroxide.

Further, it is preferable to appropriately select and perform various surface treatments as described above so that a surface having such a material can be obtained.
Further, instead of the surface treatment, an intermediate layer is formed in advance in at least the region where the bonding film 3 of the first optical component 2 is to be formed and the region where the bonding film 3 of the second optical component 4 is in close contact. Is preferred.
The intermediate layer may have any function. For example, a layer having a function of improving adhesion to the bonding film 3, a cushioning function (buffer function), a function of reducing stress concentration, and the like are preferable. By using such an intermediate layer, a highly reliable laminated optical element can be obtained.

Examples of the constituent material of the intermediate layer include metal oxides, oxide materials such as silicon oxide, metal nitrides, nitride materials such as silicon nitride, carbon such as graphite and diamond-like carbon. Materials, silane coupling agents, thiol compounds, metal alkoxides, self-assembled film materials such as metal-halogen compounds, resin adhesives, resin films, resin coating materials, various rubber materials, resins such as various elastomers A system material etc. are mentioned, Among these, it can use combining 1 type (s) or 2 or more types.
Further, among the intermediate layers formed of these materials, the bonding strength of the laminated optical element 5 can be particularly increased by the intermediate layer formed of the oxide-based material.

[2] Next, as shown in FIG. 1B, the edge (ineffective region) 3b of the bonding film 3 is exposed to plasma.
When exposed to plasma, the leaving group 303 is detached from the Si skeleton 301 on the surface of the edge 3 b of the bonding film 3. Since an active hand is generated after the leaving group 303 is detached, stable adhesion with the second optical component 4 is expressed at the edge 3 b of the bonding film 3. As a result, the edge 3b of the bonding film 3 can be stably and firmly bonded to the second optical component 4 based on chemical bonding.

  Here, the bonding film 3 before being exposed to plasma has a Si skeleton 301 and a leaving group 303 as shown in FIG. When energy is applied to the bonding film 3, a leaving group 303 (in this embodiment, a methyl group) near the surface is detached from the Si skeleton 301 in particular. As a result, as shown in FIG. 4, active hands 304 are generated on the surface 35 of the bonding film 3 and activated. As a result, adhesiveness develops on the surface of the bonding film 3.

It should be noted that “activating” the bonding film 3 means that the surface 35 of the bonding film 3 and the internal leaving group 303 are removed, and a bond not terminated in the Si skeleton 301 (hereinafter referred to as “unbonded bond”). "Or" dangling bond "), a state in which this dangling bond is terminated by a hydroxyl group (OH group), or a state in which these states are mixed.
Therefore, the active hand 304 means a dangling bond (dangling bond) or a dangling bond terminated by a hydroxyl group. According to such an active hand 304, particularly strong bonding can be performed to the second optical component 4.

  In the present invention, only the edge (ineffective region) 3b through which the light hardly transmits is exposed to the plasma in the bonding film 3, and the first optical component 2 and the second optical component 4 are exposed through the edge 3b. And joined. In the laminated optical element 5 thus obtained, the edge 3b is generally often covered with a frame or the like, and is often optically designed so that light is hardly applied or light is not transmitted. In the part 3b, the bonding film 3 is hardly altered or deteriorated by light. For this reason, the laminated optical element 5 which can suppress the adhesive fall accompanying quality change and deterioration of the joining film | membrane 3 and can maintain high reliability over a long term is obtained.

Furthermore, even if light hits the edge 3b of the bonding film 3 to cause a problem such as discoloration, the problem does not affect the light passing through the effective diameter 3a. Will not cause a drop in
On the other hand, the effective diameter (effective region) 3a inside the edge 3b is a region where optical characteristics should be secured in the laminated optical element 5, and light is generally transmitted through this region.

  As the plasma exposed to the bonding film 3, atmospheric pressure plasma is preferably used. According to atmospheric pressure plasma, plasma treatment can be easily performed without using expensive equipment such as decompression means. In addition to the direct plasma method in which plasma is generated in the vicinity of the bonding film 3, a remote plasma method or a downflow plasma method in which the object to be processed and the plasma generation unit are separated is also preferably used for this plasma treatment. According to the direct plasma method, since plasma is generated in the vicinity of the bonding film 3, plasma processing can be performed efficiently and uniformly. Further, when the object to be processed and the plasma generating part are separated from each other, the object to be processed and the plasma generating part do not interfere with each other, so that the object to be processed can be avoided from ion damage.

Further, when the plasma treatment is performed in a reduced pressure atmosphere, there is a possibility that a gas unintentionally confined inside the bonding film 3 or a gas generated over time is forcibly extracted to the outside of the bonding film 3. . When such a phenomenon occurs, the bonding film 3 is damaged, resulting in a decrease in adhesiveness and a decrease in optical performance.
On the other hand, by performing plasma treatment under atmospheric pressure, it is possible to prevent the bonding film 3 from being damaged, and to obtain the bonding film 3 excellent in adhesiveness and optical performance.

In addition, examples of the gas that generates plasma include Ar, He, H ₂ , N ₂ , and O ₂ , and a mixture of two or more of these may be used. Among these, in consideration of oxidation of the bonding film 3, an inert gas such as Ar or He is preferably used.
The plasma treatment can also be performed using a plasma polymerization apparatus 100 shown in FIG. That is, after the bonding film 3 is formed using the plasma polymerization apparatus 100 shown in FIG. 5, the plasma treatment of this step can be continuously performed without removing the bonding film 3 from the apparatus, so that the optical element of the present invention is manufactured. The method can be simplified.

  Further, when plasma is generated by discharge, the voltage applied between the electrodes is preferably a high frequency of MHz or higher. Thereby, compared with the case of direct current discharge, since a discharge start voltage falls, a discharge state can be maintained easily. Moreover, by using a high frequency, the ionization degree in plasma becomes high and a plasma density becomes high. As a result, the elimination of the leaving group 303 by plasma can be performed efficiently.

The frequency of the voltage applied between the electrodes is not particularly limited, but is preferably about 10 to 50 MHz, and more preferably about 10 to 40 MHz.
In order to selectively expose the edge 3b of the bonding film 3 to plasma, plasma processing is performed through the mask 6 having the window 61 having a shape corresponding to the shape of the edge 3b in plan view. Good.

  In the present embodiment, the edge 3b of the bonding film 3 is exposed to the plasma as the step [2]. However, the edge 3b can exhibit adhesiveness by other methods. Specific examples include energy ray irradiation, heating, pressurization, and exposure to ozone. In addition, although it may be made to irradiate with an ultraviolet-ray, in this case, it is necessary to control the integrated light quantity so that all the leaving groups 303 at the edge 3b are not detached.

[3] Next, as shown in FIG. 1C, the effective diameter (effective region) 3a of the bonding film 3 is irradiated with ultraviolet rays (second step).
When an ultraviolet ray of a predetermined integrated light quantity or more is irradiated, the leaving group 303 is detached from the Si skeleton 301 at the effective diameter 3 a of the bonding film 3. When such elimination of the leaving group 303 occurs continuously, most of the leaving groups 303 are finally eliminated from the Si skeleton 301, and only the Si skeleton 301 remains. .

  In such a state, the inorganic component having an effective diameter 3a of the bonding film 3 remains and is mineralized. By this mineralization, the composition of the effective diameter 3a of the bonding film 3 becomes similar to the composition of silicon oxide and is chemically stable. For this reason, the effective diameter 3a of the bonding film 3 has excellent weather resistance over a long period of time without deterioration or deterioration in accordance with light, compared to before the mineralization. Further, the refractive index is stable at a refractive index (approximately 1.35 to 1.6) close to that of quartz glass or quartz crystal over a long period of time.

As a result, the space between the first optical component 2 and the second optical component 4 is filled with a medium having a refractive index higher than that of the air layer, and the finally obtained laminated optical element 5 is so-called The optical loss called “Fresnel reflection loss” is sufficiently suppressed. That is, the laminated optical element 5 has excellent light transmittance.
Note that the amount of elimination of the leaving group 303 by the irradiation of ultraviolet rays is correlated with the integrated amount of ultraviolet rays. Based on this correlation, almost all of the leaving groups 303 having an effective diameter 3a can be released by irradiating the bonding film 3 with ultraviolet rays having a predetermined cumulative light amount or more. In this case, 90% or more of the leaving group 303 having an effective diameter 3a is preferably eliminated, and more preferably 95% or more is eliminated.

In addition, since the thermal expansion coefficient of the bonding film 3 after mineralization is relatively close to the thermal expansion coefficient of quartz or quartz glass, the difference between these thermal expansion coefficients becomes small, and deformation after bonding can be suppressed. .
Moreover, the energy of the ultraviolet rays irradiated in this step does not cut the siloxane (Si—O) bond in the bonding film 3 and a chemical bond (for example, Si—C bond) having a bond energy smaller than that of the siloxane bond. It is preferable that the energy be cut. By using such ultraviolet rays, the leaving group 303 in the bonding film 3 can be reliably removed.

Specifically, it is preferable to use ultraviolet rays having a wavelength of about 126 to 300 nm, and it is more preferable to use ultraviolet rays having a wavelength of about 160 to 200 nm.
Further, the accumulated light quantity of the ultraviolet rays is preferably 1 J / cm ² or more, more preferably 10 J / cm ² or more, although it varies slightly depending on the thickness of the bonding film 3 and the wavelength of the ultraviolet rays. Thereby, the effective diameter 3a of the bonding film 3 can be reliably mineralized.

Further, as described above, the cumulative amount of ultraviolet light is represented by the product of illuminance and irradiation time. Therefore, when using the UV lamp as a light source of ultraviolet rays, the illuminance is preferably from ^1mW / cm ^{2 ~1W} / cm 2 or ^so, more preferably from 5mW / cm ² ~50mW / cm 2 approximately.
Moreover, although an ultraviolet-ray may be irradiated continuously in time, you may irradiate intermittently (pulse form).

In order to selectively irradiate the effective diameter 3a of the bonding film 3 with ultraviolet rays, plasma processing is performed through a mask 7 having a window portion 71 having a shape corresponding to the planar view shape of the effective diameter 3a. That's fine.
Moreover, ultraviolet rays may be irradiated as laser light. Since the laser beam has a very high directivity, the bonding film 3 can be irradiated with ultraviolet rays locally.

The bonding film 3 may be irradiated with ultraviolet rays in any atmosphere, but is preferably a dry atmosphere. As a result, it is possible to prevent water vapor in the atmosphere from adsorbing to the traces of chemical bonds that have been cut by irradiation with ultraviolet rays, and to prevent unintended changes in the composition of the bonding film 3.
Specifically, the dew point of the atmosphere is preferably −10 ° C. or lower, and more preferably −20 ° C. or lower.

  When the leaving group 303 is detached by irradiating the effective diameter 3a of the bonding film 3 with ultraviolet rays, the refractive index of the effective diameter 3a changes and active hands are generated on the surface and inside the effective diameter 3a. Thereby, although the adhesiveness with the 2nd optical component 4 expresses on the surface of the effective diameter 3a, the strength of the adhesiveness is weak compared with the adhesiveness of the edge part 3b. One of the causes is that most of the leaving groups 303 having an effective diameter of 3a are eliminated with the irradiation of ultraviolet rays, and many active hands are generated thereby, so that there is a high probability that adjacent active hands are recombined. Become. As a result, the adhesiveness of the effective diameter 3a is limited compared to the edge 3b.

[4] Next, as shown in FIG. 2 (d), the first optical component 2 and the second optical component 4 are brought into close contact with the activated bonding film 3 and the second optical component 4. And paste together. Thereby, the laminated optical element 5 as shown in FIG. 2E is obtained (third step).
In the laminated optical element 5 obtained in this way, it is not a bond based on a physical bond such as an anchor effect, but a covalent bond, unlike the adhesive used in the conventional optical element manufacturing method. Bonding is based on such a strong chemical bond that occurs in a short time. For this reason, the laminated optical element 5 can be formed in a short time, is extremely difficult to peel off, and is difficult to cause uneven bonding.

In addition, according to such a method, unlike the conventional solid bonding, the heat treatment at a high temperature (for example, 700 ° C. or higher) is not required, so the first optical component composed of a material having low heat resistance. The second and second optical components 4 can also be used for bonding.
In addition, since the first optical component 2 and the second optical component 4 are bonded via the bonding film 3, there is no restriction on the constituent materials of the first optical component 2 and the second optical component 4. There are also advantages.

From the above, according to the present invention, the range of selection of each constituent material of the first optical component 2 and the second optical component 4 can be increased.
In the present embodiment, the bonding film 3 is provided on only one of the first optical component 2 and the second optical component 4 used for bonding (in the present embodiment, the first optical component 2). ing. When forming the bonding film 3 on the first optical component 2, the first optical component 2 is exposed to plasma for a relatively long time depending on the method of forming the bonding film 3. Then, the second optical component 4 is not exposed to plasma. Therefore, for example, even when the durability of the second optical component 4 against plasma is extremely low, according to the method according to the present embodiment, the first optical component 2 and the second optical component 4 are firmly connected. Can be joined. Therefore, there is an advantage that the material constituting the second optical component 4 can be selected from a wide range of materials without much consideration of durability against plasma.

Here, the mechanism by which the first optical component 2 and the second optical component 4 are joined in this step will be described.
For example, a case where a hydroxyl group is exposed on the bonding surface of the second optical component 4 will be described as an example. In this step, the surface 35 of the bonding film 3 and the bonding surface of the second optical component 4 are in contact with each other. In addition, when these are bonded together, the hydroxyl group present on the surface 35 of the bonding film 3 and the hydroxyl group present on the bonding surface of the second optical component 4 are attracted to each other by hydrogen bonding, and there is an attractive force between the hydroxyl groups. appear. It is inferred that the first optical component 2 and the second optical component 4 are joined by this attractive force.

Further, the hydroxyl groups attracting each other by this hydrogen bond are dehydrated and condensed depending on the temperature condition or the like. As a result, at the contact interface between the first optical component 2 and the second optical component 4, the bonds in which the hydroxyl groups are bonded are bonded through oxygen atoms. Thereby, it is guessed that the 1st optical component 2 and the 2nd optical component 4 are joined more firmly.
Note that the active state of the surface of the bonding film 3 activated in the step [3] relaxes with time. For this reason, it is preferable to perform this process [4] as soon as possible after completion of the process [3]. Specifically, after the completion of the step [3], the step [4] is preferably performed within 60 minutes, and more preferably within 5 minutes. If it is within this time, the surface of the bonding film 3 maintains a sufficiently active state. Therefore, when the first optical component 2 and the second optical component 4 are bonded together in this step, there is a gap between them. Sufficient bonding strength can be obtained.

In other words, since the bonding film 3 before activation is a bonding film having the Si skeleton 301, it is chemically relatively stable and has excellent weather resistance. For this reason, the bonding film 3 before being activated is suitable for long-term storage. Therefore, a large amount of the first optical component 2 having such a bonding film 3 is manufactured or purchased and stored, and the process [3] is performed only for the necessary number immediately before bonding in this process. If the plasma treatment described in the above is performed, it is effective from the viewpoint of manufacturing efficiency of the laminated optical element 5.
As described above, the laminated optical element (optical element of the present invention) 5 shown in FIG. 2E can be obtained.
In FIG. 2E, the second optical component 4 is overlaid so as to cover the entire surface of the bonding film 3, but their relative positions may be shifted from each other. That is, the second optical component 4 may protrude from the bonding film 3.

In the laminated optical element 5 thus obtained, the bonding strength between the first optical component 2 and the second optical component 4 is preferably 5 MPa (50 kgf / cm ² ) or more, preferably 10 MPa (100 kgf / Cm ² ) or more. The laminated optical element 5 having such a bonding strength can sufficiently prevent the peeling.
In addition, after obtaining the laminated optical element 5, the laminated optical element 5 is subjected to at least one step (laminated optical element 5) of the following two steps ([5A] and [5B]) as necessary. The step of increasing the bonding strength) may be performed. Thereby, the joint strength of the laminated optical element 5 can be further improved.

[5A] As shown in FIG. 2 (f), the obtained laminated optical element 5 is pressed in a direction in which the first optical component 2 and the second optical component 4 approach each other.
Thereby, the surface of the bonding film 3 is closer to the surface of the first optical component 2 and the surface of the second optical component 4, respectively, and the bonding strength in the laminated optical element 5 can be further increased.
Further, by pressurizing the laminated optical element 5, the gap remaining at the bonding interface in the laminated optical element 5 can be crushed and the bonding area can be further expanded. Thereby, the joint strength in the laminated optical element 5 can be further increased.
At this time, the pressure when pressurizing the laminated optical element 5 is a pressure that does not damage the laminated optical element 5 and is preferably as high as possible. Thereby, the joint strength in the laminated optical element 5 can be increased in proportion to this pressure.

In addition, what is necessary is just to adjust this pressure suitably according to conditions, such as each constituent material of each of the 1st optical component 2 and the 2nd optical component 4, each thickness, and a joining apparatus. Specifically, it is preferably about 0.2 to 10 MPa, preferably about 1 to 5 MPa, although it varies slightly depending on the constituent materials and thicknesses of the first optical component 2 and the second optical component 4. It is more preferable that Thereby, the joining strength of the laminated optical element 5 can be reliably increased. The pressure may exceed the upper limit, but depending on the constituent materials of the first optical component 2 and the second optical component 4, the first optical component 2 and the second optical component 4 There is a risk of damage.
The time for pressurization is not particularly limited, but is preferably about 10 seconds to 30 minutes. In addition, what is necessary is just to change suitably the time to pressurize according to the pressure at the time of pressurizing. Specifically, the higher the pressure at which the laminated optical element 5 is pressed, the higher the bonding strength can be achieved even if the pressing time is shortened.

[5B] As shown in FIG. 2F, the obtained laminated optical element 5 is heated.
Thereby, the joint strength in the laminated optical element 5 can be further increased.
At this time, the temperature when heating the laminated optical element 5 is not particularly limited as long as it is higher than room temperature and lower than the heat-resistant temperature of the laminated optical element 5, but is preferably about 25 to 100 ° C., more preferably 50. ˜100 ° C. Heating at a temperature in such a range can reliably increase the bonding strength while reliably preventing the laminated optical element 5 from being altered or deteriorated by heat.

The heating time is not particularly limited, but is preferably about 1 to 30 minutes.
Moreover, when performing both said process [5A] and [5B], it is preferable to perform these simultaneously. That is, as shown in FIG. 2F, it is preferable to heat the laminated optical element 5 while applying pressure. Thereby, the effect by pressurization and the effect by heating are exhibited synergistically, and the joint strength of the laminated optical element 5 can be particularly increased.
By performing the steps as described above, it is possible to easily further improve the bonding strength in the laminated optical element 5.
Here, the bonding film 3 will be described in detail.

  As described above, the bonding film 3 is formed by a plasma polymerization method. As shown in FIG. 3, the Si skeleton 301 including a siloxane (Si—O) bond 302 and having a random atomic structure, It has a leaving group 303 bonded to the Si skeleton 301. Such a bonding film 3 becomes a strong film that is difficult to be deformed due to the influence of the Si skeleton 301 including the siloxane bond 302 and having a random atomic structure. This is presumably because the crystallinity of the Si skeleton 301 becomes low, so that defects such as dislocations and misalignments at the grain boundaries are less likely to occur. For this reason, the bonding film 3 itself has high bonding strength, chemical resistance, light resistance and dimensional accuracy, and the finally obtained laminated optical element 5 also has bonding strength, chemical resistance, light resistance and dimensional accuracy. A high one is obtained.

  In such a bonding film 3, when energy is applied, the leaving group 303 is detached from the Si skeleton 301, and as shown in FIG. 4, active hands 304 are generated on the surface 35 and inside of the bonding film 3. It is. As a result, adhesiveness is developed on the surface of the bonding film 3. When such adhesiveness is developed, the bonding film 3 can be firmly and efficiently bonded to the second optical component 4 with high dimensional accuracy.

Note that the bond energy between the leaving group 303 and the Si skeleton 301 is smaller than the bond energy of the siloxane bond 302 in the Si skeleton 301. For this reason, the bonding film 3 can selectively cut the bond between the leaving group 303 and the Si skeleton 301 and remove the leaving group 303 by applying energy without almost cutting off the Si skeleton 301. it can.
Further, such a bonding film 3 is a solid having no fluidity. For this reason, conventionally, the thickness and shape of the adhesive layer (bonding film 3) hardly change compared to a liquid or viscous liquid adhesive. Thereby, the dimensional accuracy of the laminated optical element 5 is remarkably higher than the conventional one. Furthermore, since the time required for curing the adhesive is not required, strong bonding can be achieved in a short time.

  Note that, in the bonding film 3, among the atoms obtained by removing H atoms from all atoms constituting the bonding film 3, the total of the Si atom content and the O atom content is about 10 to 90 atomic%. Is preferable, and it is more preferable that it is about 20-80 atomic%. If Si atoms and O atoms are contained in the above-mentioned range, the bonding film 3 forms a strong network of Si atoms and O atoms, and the bonding film 3 itself becomes strong. In addition, the bonding film 3 exhibits particularly high bonding strength with respect to the first optical component 2 and the second optical component 4.

The abundance ratio of Si atoms and O atoms in the bonding film 3 is preferably about 3: 7 to 7: 3, and more preferably about 4: 6 to 6: 4. By setting the abundance ratio of Si atoms and O atoms to be within the above range, the stability of the bonding film 3 is increased, and the first optical component 2 and the second optical component 4 are bonded more firmly. Will be able to.
The crystallinity of the Si skeleton 301 in the bonding film 3 is preferably 45% or less, and more preferably 40% or less. As a result, the Si skeleton 301 includes a sufficiently random atomic structure. For this reason, the characteristics of the Si skeleton 301 described above become obvious, and the dimensional accuracy and adhesiveness of the bonding film 3 become more excellent.

  Note that the crystallinity of the Si skeleton 301 can be measured by a general crystallinity measurement method, and specifically, a method of measuring based on the intensity of scattered X-rays in a crystal portion (X-ray method). , The method of obtaining from the intensity of the crystallization band of infrared absorption (infrared method), the method of obtaining based on the area under the differential curve of nuclear magnetic resonance absorption (nuclear magnetic resonance absorption method), It can be measured by a chemical method utilizing the difficulty.

  The bonding film 3 preferably contains Si—H bonds in the structure. This Si-H bond is generated in the polymer when the silane undergoes a polymerization reaction by the plasma polymerization method. At this time, if the Si-H bond inhibits the regular formation of the siloxane bond, Conceivable. For this reason, the siloxane bond is formed so as to avoid the Si—H bond, and the regularity of the atomic structure of the Si skeleton 301 is lowered. Thus, according to the plasma polymerization method, the Si skeleton 301 having a low crystallinity can be efficiently formed.

  On the other hand, the greater the Si—H bond content in the bonding film 3, the lower the crystallinity. Specifically, in the infrared absorption spectrum of the bonding film 3, when the intensity of the peak attributed to the siloxane bond is 1, the intensity of the peak attributed to the Si—H bond is about 0.001 to 0.2. It is preferable that it is about 0.002-0.05, and it is further more preferable that it is about 0.005-0.02. When the ratio of the Si—H bond to the siloxane bond is within the above range, the atomic structure in the bonding film 3 is relatively random. For this reason, when the peak intensity of the Si—H bond is within the above range with respect to the peak intensity of the siloxane bond, the bonding film 3 is particularly excellent in bonding strength, chemical resistance, and dimensional accuracy.

Further, as described above, the leaving group 303 bonded to the Si skeleton 301 acts to generate an active hand in the bonding film 3 by detaching from the Si skeleton 301. Therefore, although the leaving group 303 is relatively easily and uniformly desorbed by being given energy, it is securely bonded to the Si skeleton 301 so as not to be desorbed when no energy is given. It needs to be a thing.
In the film formation by the plasma polymerization method, the component of the source gas is polymerized to generate a Si skeleton 301 containing a siloxane bond and a residue bonded thereto. For example, this residue is a leaving group. 303.

  From this point of view, the leaving group 303 includes an H atom, a B atom, a C atom, an N atom, an O atom, a P atom, an S atom, and a halogen atom, or each of these atoms. What consists of at least 1 sort (s) selected from the group which consists of an atomic group arrange | positioned so that it may couple | bond with frame | skeleton 301 is used preferably. Such a leaving group 303 is relatively excellent in bond / elimination selectivity by energy application. For this reason, such a leaving group 303 can sufficiently satisfy the above-described necessity, and the adhesiveness of the bonding film 3 can be made higher.

  Examples of the atomic group (group) arranged so that each atom as described above is bonded to the Si skeleton 301 include, for example, an alkyl group such as a methyl group and an ethyl group, and an alkenyl group such as a vinyl group and an allyl group. Aldehyde group, ketone group, carboxyl group, amino group, amide group, nitro group, halogenated alkyl group, mercapto group, sulfonic acid group, cyano group, isocyanate group and the like.

Among these groups, the leaving group 303 is particularly preferably an alkyl group. Since the alkyl group has high chemical stability, the bonding film 3 containing the alkyl group is excellent in weather resistance and chemical resistance.
Here, when the leaving group 303 is a methyl group (—CH ₃ ), the preferred content is defined as follows from the peak intensity in the infrared light absorption spectrum.

That is, in the infrared absorption spectrum of the bonding film 3, when the intensity of the peak attributed to the siloxane bond is 1, the intensity of the peak attributed to the methyl group is preferably about 0.05 to 0.45. More preferably, it is about 0.1 to 0.4, and more preferably about 0.2 to 0.3. Since the ratio of the peak intensity of the methyl group to the peak intensity of the siloxane bond is within the above range, it is necessary and sufficient in the bonding film 3 while preventing the methyl group from inhibiting the generation of the siloxane bond more than necessary. Since a number of active hands are generated, sufficient adhesiveness is generated in the bonding film 3. Further, the bonding film 3 exhibits sufficient weather resistance and chemical resistance due to the methyl group.
Examples of the constituent material of the bonding film 3 having such characteristics include a polymer containing a siloxane bond such as polyorganosiloxane and an organic group capable of forming a leaving group 303 bonded thereto.

The bonding film 3 made of polyorganosiloxane itself has excellent mechanical properties. In addition, it exhibits particularly excellent adhesion to many materials. Therefore, the bonding film 3 made of polyorganosiloxane adheres particularly firmly to the first optical component 2 and also exhibits a particularly strong adhesion force to the second optical component 4, and as a result. As a result, the first optical component 2 and the second optical component 4 can be firmly bonded.
Polyorganosiloxane usually exhibits water repellency (non-adhesiveness), but when given energy, it can easily desorb organic groups, changes to hydrophilicity, and exhibits adhesiveness. However, there is an advantage that the non-adhesiveness and the adhesiveness can be controlled easily and reliably.

  This water repellency (non-adhesiveness) is mainly due to the action of alkyl groups contained in the polyorganosiloxane. Therefore, the bonding film 3 made of polyorganosiloxane exhibits adhesiveness on the surface 35 when energy is applied thereto, and at the portion other than the surface 35, the above-described action / effect by the alkyl group is obtained. Has the advantage of being Therefore, such a bonding film 3 has excellent weather resistance and chemical resistance, and is effectively used, for example, in assembling an optical element or a droplet discharge head that is exposed to chemicals for a long time. It will be a thing.

  Further, among polyorganosiloxanes, those mainly composed of a polymer of octamethyltrisiloxane are preferred. The bonding film 3 mainly composed of a polymer of octamethyltrisiloxane is particularly excellent in adhesiveness. Moreover, since the raw material which has octamethyltrisiloxane as a main component is liquid at normal temperature and has an appropriate viscosity, there is also an advantage that it is easy to handle.

The average thickness of the bonding film 3 is preferably about 1 to 1000 nm, and more preferably about 2 to 800 nm. By setting the average thickness of the bonding film 3 within the above range, these can be bonded more firmly while preventing the dimensional accuracy of the laminated optical element 5 from being significantly lowered.
That is, when the average thickness of the bonding film 3 is less than the lower limit, sufficient bonding strength may not be obtained. On the other hand, when the average thickness of the bonding film 3 exceeds the upper limit, the dimensional accuracy of the laminated optical element 5 may be reduced.

  Furthermore, if the average thickness of the bonding film 3 is within the above range, a certain degree of shape followability is ensured for the bonding film 3. For this reason, for example, even when unevenness is present on the bonding surface of the first optical component 2 (surface adjacent to the bonding film 3), it follows the shape of the unevenness depending on the height of the unevenness. The bonding film 3 can be deposited on the substrate. As a result, the bonding film 3 can absorb the unevenness and reduce the height of the unevenness generated on the surface. And when the 1st optical component 2 and the 2nd optical component 4 are bonded together, both adhesiveness can be improved.

Note that the degree of the shape followability as described above becomes more significant as the thickness of the bonding film 3 increases. Therefore, the thickness of the bonding film 3 should be as large as possible in order to sufficiently ensure the shape following ability.
The bonding film 3 has been described in detail above. Such a bonding film 3 is produced by a plasma polymerization method. According to the plasma polymerization method, the dense and homogeneous bonding film 3 can be efficiently produced. Thereby, the bonding film 3 can be particularly strongly bonded to the second optical component 4. Furthermore, the bonding film 3 manufactured by the plasma polymerization method is maintained for a relatively long time in a state where energy is applied and activated. For this reason, the manufacturing process of the laminated optical element 5 can be simplified and efficient.
Hereinafter, a method for producing the bonding film 3 will be described.

First, prior to the description of the method for manufacturing the bonding film 3, a plasma polymerization apparatus used for manufacturing the bonding film 3 by performing plasma polymerization on the first optical component 2 will be described.
FIG. 5 is a longitudinal sectional view schematically showing a plasma polymerization apparatus used in the method for producing an optical element of the present invention. In the following description, the upper side in FIG. 5 is referred to as “upper” and the lower side is referred to as “lower”.
The plasma polymerization apparatus 100 shown in FIG. 5 includes a chamber 101, a first electrode 130 that supports the first optical component 2, a second electrode 140, and a power source that applies a high-frequency voltage between the electrodes 130 and 140. A circuit 180, a gas supply unit 190 that supplies gas into the chamber 101, and an exhaust pump 170 that exhausts the gas in the chamber 101 are provided. Among these parts, the first electrode 130 and the second electrode 140 are provided in the chamber 101. Hereinafter, each part will be described in detail.

The chamber 101 is a container that can keep the inside airtight, and is used with the inside being in a reduced pressure (vacuum) state. Therefore, the chamber 101 has pressure resistance that can withstand a pressure difference between the inside and the outside.
The chamber 101 shown in FIG. 5 has a substantially cylindrical chamber body whose axis is arranged along the horizontal direction, a circular side wall that seals the left opening of the chamber body, and a circle that seals the right opening. And side walls.

A supply port 103 is provided above the chamber 101, and an exhaust port 104 is provided below the chamber 101. A gas supply unit 190 is connected to the supply port 103, and an exhaust pump 170 is connected to the exhaust port 104.
In this embodiment, the chamber 101 is made of a highly conductive metal material and is electrically grounded via the ground wire 102.

The first electrode 130 has a plate shape and supports the first optical component 2.
The first electrode 130 is provided on the inner wall surface of the side wall of the chamber 101 along the vertical direction, whereby the first electrode 130 is electrically grounded via the chamber 101. As shown in FIG. 5, the first electrode 130 is provided concentrically with the chamber body.

An electrostatic chuck (suction mechanism) 139 is provided on the surface of the first electrode 130 that supports the first optical component 2.
As shown in FIG. 5, the electrostatic chuck 139 can support the first optical component 2 along the vertical direction. Further, even if the first optical component 2 has a slight warp, the first optical component 2 can be subjected to a plasma treatment in a state where the warp is corrected by being attracted to the electrostatic chuck 139.

The second electrode 140 is provided to face the first electrode 130 with the first optical component 2 interposed therebetween. Note that the second electrode 140 is provided in a state of being separated (insulated) from the inner wall surface of the side wall of the chamber 101.
A high frequency power source 182 is connected to the second electrode 140 via a wiring 184. A matching box (matching unit) 183 is provided in the middle of the wiring 184. The wiring 184, the high-frequency power source 182 and the matching box 183 constitute a power circuit 180.

According to such a power supply circuit 180, since the first electrode 130 is grounded, a high frequency voltage is applied between the first electrode 130 and the second electrode 140. As a result, an electric field whose direction is reversed at a high frequency is induced in the gap between the first electrode 130 and the second electrode 140.
The gas supply unit 190 supplies a predetermined gas into the chamber 101.

  A gas supply unit 190 shown in FIG. 5 stores a liquid storage unit 191 that stores a liquid film material (raw material liquid), a vaporizer 192 that vaporizes the liquid film material to change it into a gaseous state, and stores a carrier gas. And a gas cylinder 193. Each of these parts and the supply port 103 of the chamber 101 are connected by a pipe 194, and a mixed gas of a gaseous film material (raw material gas) and a carrier gas is supplied from the supply port 103 into the chamber 101. It is configured to supply.

The liquid film material stored in the liquid storage unit 191 is a raw material that is polymerized by the plasma polymerization apparatus 100 to form a polymer film on the surface of the first optical component 2.
Such a liquid film material is vaporized by the vaporizer 192 and is supplied into the chamber 101 as a gaseous film material (raw material gas). The source gas will be described in detail later.

The carrier gas stored in the gas cylinder 193 is a gas that is discharged due to the action of an electric field and introduced to maintain this discharge. Examples of such a carrier gas include Ar gas and He gas.
A diffusion plate 195 is provided near the supply port 103 in the chamber 101.
The diffusion plate 195 has a function of promoting the diffusion of the mixed gas supplied into the chamber 101. Thereby, the mixed gas can be dispersed in the chamber 101 with a substantially uniform concentration.

  The exhaust pump 170 exhausts the inside of the chamber 101, and includes, for example, an oil rotary pump, a turbo molecular pump, or the like. Thus, by exhausting the chamber 101 and reducing the pressure, the gas can be easily converted into plasma. In addition, contamination and oxidation of the first optical component 2 due to contact with the air atmosphere can be prevented, and reaction products resulting from the plasma treatment can be effectively removed from the chamber 101.

The exhaust port 104 is provided with a pressure control mechanism 171 that adjusts the pressure in the chamber 101. Thereby, the pressure in the chamber 101 is appropriately set according to the operation state of the gas supply unit 190.
Next, a method for producing the bonding film 3 on the first optical component 2 using the plasma polymerization apparatus 100 will be described.

FIG. 6 is a view (longitudinal sectional view) for explaining a method of producing the bonding film 3 on the first optical component 2. In the following description, the upper side in FIG. 6 is referred to as “upper” and the lower side is referred to as “lower”.
The bonding film 3 is obtained by supplying a mixed gas of a source gas and a carrier gas in a strong electric field, thereby polymerizing molecules in the source gas and depositing the polymer on the first optical component 2. be able to. Details will be described below.

First, the first optical component 2 is prepared, and the surface treatment as described above is performed on the upper surface 25 of the first optical component 2 as necessary.
Next, after the first optical component 2 is housed in the chamber 101 of the plasma polymerization apparatus 100 and sealed, the chamber 101 is depressurized by the operation of the exhaust pump 170.
Next, the gas supply unit 190 is operated to supply a mixed gas of the source gas and the carrier gas into the chamber 101. The supplied mixed gas is filled in the chamber 101 (see FIG. 6A).

Here, the ratio (mixing ratio) of the source gas in the mixed gas is slightly different depending on the type of the source gas and the carrier gas, the target film forming speed, and the like. For example, the ratio of the source gas in the mixed gas is 20 It is preferable to set to about -70%, and it is more preferable to set to about 30-60%. As a result, it is possible to optimize the conditions for formation (film formation) of the polymer film.
Further, the flow rate of the gas to be supplied is appropriately determined depending on the type of gas, the target film formation rate, the film thickness, etc., and is not particularly limited, but usually the flow rates of the source gas and the carrier gas are respectively , Preferably about 1 to 100 ccm, more preferably about 10 to 60 ccm.

  Next, the power supply circuit 180 is activated, and a high frequency voltage is applied between the pair of electrodes 130 and 140. As a result, gas molecules existing between the pair of electrodes 130 and 140 are ionized to generate plasma. The molecules in the source gas are polymerized by the energy of the plasma, and the polymer adheres to and deposits on the first optical component 2 as shown in FIG. As a result, a bonding film 3 made of a plasma polymerized film is formed on the first optical component 2 (see FIG. 6C).

Further, the surface of the first optical component 2 is activated and cleaned by the action of plasma. For this reason, the polymer of the source gas is easily deposited on the surface of the first optical component 2, and the bonding film 3 can be stably formed. As described above, according to the plasma polymerization method, the adhesion strength between the first optical component 2 and the bonding film 3 can be further increased regardless of the constituent material of the first optical component 2.
Examples of the source gas include organosiloxanes such as methylsiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, decamethylcyclopentasiloxane, octamethylcyclotetrasiloxane, and methylphenylsiloxane.

The plasma polymerized film obtained by using such a raw material gas, that is, the bonding film 3 is composed of a polymer obtained by polymerizing these raw materials, that is, a polyorganosiloxane.
In the plasma polymerization, the frequency of the high frequency applied between the pair of electrodes 130 and 140 is not particularly limited, but is preferably about 1 kHz to 100 MHz, and more preferably about 10 to 60 MHz.

Further, the power density of the high frequency is not particularly limited, and is preferably about 0.01~100W / cm ^2, more preferably about ^{0.1~50W / cm 2, 1~40W / cm} 2 More preferably, it is about. By setting the high-frequency power density within the above range, the Si skeleton 301 having a random atomic structure can be reliably secured while preventing the plasma gas from being added to the source gas more than necessary because the high-frequency power density is too high. Can be formed. That is, when the high-frequency output density is lower than the lower limit value, the molecules in the raw material gas cannot cause a polymerization reaction, and the bonding film 3 may not be formed. On the other hand, when the power density of the high frequency exceeds the upper limit, the structure that can be the leaving group 303 is separated from the Si skeleton 301 due to decomposition of the source gas or the like, and the leaving group in the resulting bonding film 3 is separated. There is a possibility that the content of 303 is lowered or the randomness of the Si skeleton 301 is lowered (regularity is increased).

Further, the pressure in the chamber 101 during film formation is preferably about 133.3 × 10 ^{−5 to} 1333 Pa (1 × 10 ^{−5 to} 10 Torr), and 133.3 × 10 ^{−4 to} 133.3 Pa ( More preferably, it is about 1 × 10 ^{−4 to} 1 Torr).
The raw material gas flow rate is preferably about 0.5 to 200 sccm, and more preferably about 1 to 100 sccm. On the other hand, the carrier gas flow rate is preferably about 5 to 750 sccm, and more preferably about 10 to 500 sccm.

The treatment time is preferably about 1 to 10 minutes, more preferably about 4 to 7 minutes.
Moreover, it is preferable that the temperature of the 1st optical component 2 is 25 degreeC or more, and it is more preferable that it is about 25-100 degreeC.
The bonding film 3 is obtained as described above.

<< Second Embodiment >>
Next, a second embodiment of the optical element manufacturing method of the present invention will be described.
FIG. 7 is a view (longitudinal sectional view) for explaining a second embodiment of the method for producing an optical element of the present invention. In the following description, the upper side in FIG. 7 is referred to as “upper” and the lower side is referred to as “lower”.
Hereinafter, although the manufacturing method of the optical element concerning 2nd Embodiment is demonstrated, it demonstrates centering around difference with the said 1st Embodiment, The description is abbreviate | omitted about the same matter.

In the method of manufacturing an optical element according to this embodiment, a bonding film is formed on the surface of each optical component 2, 4, and each optical component 2, 4 is bonded so that the bonding films are in close contact with each other. Except for this, it is the same as the first embodiment.
That is, in the method for manufacturing an optical element according to the present embodiment, the first optical component 2 and the second optical component 4 are prepared, and the bonding film 31 is formed on the surface of the first optical component 2 by plasma polymerization. And the step of forming the bonding film 32 on the surface of the second optical component 4, and the edge (invalid region) 3b of each bonding film 31, 32 is exposed to plasma, and the effective diameter (Effective area) The first optical component 2 and the second optical component 4 are bonded together so that the bonding films 31 and 32 are in close contact with each other. And obtaining a process. Hereafter, each process of the manufacturing method of the optical element concerning this embodiment is demonstrated sequentially.

[1] First, as in the first embodiment, the first optical component 2 and the second optical component 4 are prepared, and the bonding film 31 is formed on the surfaces of the optical components 2 and 4 by plasma polymerization. , 32 are formed (see FIG. 7A).
[2] Next, as shown in FIG. 7A, the edge (ineffective region) 3 b of each of the bonding films 31 and 32 is exposed to plasma.
When exposed to plasma, the leaving group 303 is detached from the Si skeleton 301 on the surface of the edge 3 b of each bonding film 31, 32. Since an active hand is generated after the leaving group 303 is detached, stable adhesion with the second optical component 4 is expressed at the edge 3 b of the bonding film 3. As a result, the edge 3b of the bonding film 3 can be stably and firmly bonded to the second optical component 4 based on chemical bonding.

[3] On the other hand, as shown in FIG. 7B, the effective diameter (effective region) 3a of each of the bonding films 31 and 32 is irradiated with ultraviolet rays.
When the ultraviolet rays are irradiated, the leaving group 303 is detached from the Si skeleton 301 at the effective diameter 3 a of each bonding film 31 and 32. If such elimination of the leaving group 303 occurs continuously, most of the leaving groups 303 are finally eliminated from the Si skeleton 301 so that only the Si skeleton 301 remains.

If it will be in such a state, the inorganic component of the effective diameter 3a of each joining film 31 and 32 will remain, and will be mineralized. By this mineralization, the composition of the effective diameter 3a of each bonding film 31, 32 becomes similar to the composition of silicon oxide. For this reason, the effective diameter 3a of each bonding film 31 and 32 has excellent weather resistance over a long period of time without deterioration or deterioration in accordance with light, compared to before the inorganicization. Further, the refractive index is stable at a refractive index (approximately 1.35 to 1.6) close to that of quartz glass or quartz crystal over a long period of time.
As a result, the space between the first optical component 2 and the second optical component 4 is filled with a medium having a refractive index higher than that of the air layer, and the finally obtained laminated optical element 5 is so-called The optical loss called “Fresnel reflection loss” is sufficiently suppressed. That is, the laminated optical element 5 has excellent light transmittance.

[4] Next, as shown in FIG. 7 (c), the first optical component 2 and the second optical component 4 are bonded so that the bonding films 31 and 32 exhibiting adhesiveness are in close contact with each other. Match. Thereby, as shown in FIG.7 (d), the laminated optical element 5a is obtained.
Here, in this step, the bonding films 31 and 32 are bonded to each other, and this bonding is assumed to be based on both or one of the following two mechanisms (i) and (ii). .

(I) For example, the case where hydroxyl groups are exposed on the surfaces 351 and 352 of the bonding films 31 and 32 will be described as an example. In this step, the first films 31 and 32 may be in close contact with each other. When the optical component 2 and the second optical component 4 are bonded together, the hydroxyl groups present on the surfaces 351 and 352 of the bonding films 31 and 32 attract each other by hydrogen bonding, and an attractive force is generated between the hydroxyl groups. . It is inferred that the first optical component 2 and the second optical component 4 are joined by this attractive force.
Further, the hydroxyl groups attracting each other by this hydrogen bond are dehydrated and condensed depending on the temperature condition or the like. As a result, between the bonding films 31 and 32, the bonds in which the hydroxyl groups are bonded are bonded via oxygen atoms. Thereby, it is guessed that the 1st optical component 2 and the 2nd optical component 4 are joined more firmly.

(Ii) When the first optical component 2 and the second optical component 4 are bonded so that the bonding films 31 and 32 are in close contact with each other, they are generated on the surfaces 351 and 352 of the bonding films 31 and 32 or inside thereof. Bonds that are not terminated (unbonded hands) rejoin. Since this recombination occurs in a complicated manner so as to overlap (entangle) with each other, a network-like bond is formed at the bonding interface. As a result, the respective base materials (Si skeleton 301) constituting the bonding films 31 and 32 are directly bonded to each other, and the bonding films 31 and 32 are integrated with each other.
By the mechanism (i) or (ii) as described above, a laminated optical element 5a (the optical element of the present invention) as shown in FIG. 7D is obtained.

The optical element manufacturing method according to each of the embodiments as described above can be used to join various optical components together.
Examples of optical components used for such bonding include optical lenses, diffraction gratings, optical filters, protective plates, photoelectric conversion elements such as solar cells, optical recording media such as optical disks, and liquid crystal display elements. And display elements such as organic EL elements and electrophoretic display elements.

<Optical element>
Here, an embodiment in which the optical element of the present invention is applied to a wave plate will be described.
FIG. 8 is a perspective view showing a wave plate (optical element) obtained by applying the optical element of the present invention.
The wave plate 9 shown in FIG. 8 is a “½ wave plate” that gives a phase difference of ½ wavelength to transmitted light, and two crystal plates 91 and 92 having birefringence are respectively provided. Are bonded so that their optical axes are orthogonal to each other. Examples of the material having birefringence include inorganic materials such as quartz, calcite, MgF ₂ , YVO ₄ , TiO ₂ , and LiNbO ₃ , and organic materials such as polycarbonate.

When light passes through such a wave plate 9, the light is separated into a polarization component parallel to the optical axis and a polarization component perpendicular to the optical axis. The separated light is delayed on one side based on the refractive index difference associated with the birefringence of the crystal plates 91 and 92, and the phase difference described above is generated.
By the way, since the accuracy of the phase difference given to the transmitted light by the wave plate 9 and the transmittance of the wave plate 9 depend on the accuracy of the plate thickness of each crystal plate 91, 92, the plate of each crystal plate 91, 92. The thickness needs to be controlled with high accuracy.

In addition, since the gap between the crystal plate 91 and the crystal plate 92 also affects the phase of transmitted light, the gap between the crystal plate 91 and the crystal plate 92 is strictly controlled, and the gap is It must be firmly bonded so that it does not change.
Therefore, in the present invention, the optical element of the present invention is applied to the wave plate 9. Thereby, the wave plate 9 in which the crystal plate 91 and the crystal plate 92 are firmly bonded via the bonding film can be easily obtained.

Further, since this bonding film can be formed in a wide area at once by a vapor phase film forming method called a plasma polymerization method, it can be formed uniformly and the film thickness is highly accurate. For this reason, the wave plate 9 having a high degree of parallelism between the crystal plate 91 and the crystal plate 92 and less aberrations such as wavefront aberration is obtained.
Furthermore, since this bonding film is very thin, the influence on the light transmitted through the wave plate 9 can be suppressed.

Further, regarding the bonding film in the wave plate 9, by making the effective diameter portion inorganic, the weather resistance of this portion is greatly improved and an air layer is not interposed inside the wave plate 9, so-called Fresnel reflection loss can be suppressed. Therefore, the wave plate 9 (the optical element of the present invention) is excellent in light resistance and light transmittance.
Further, since the thermal expansion coefficient of the effective diameter portion of the bonding film is equal to the thermal expansion coefficient of each of the crystal plates 91 and 92, deformation of the wave plate 9 due to temperature change can be suppressed.

The wave plate 9 may be a quarter wave plate, a 1/8 wave plate or the like in addition to the half wave plate.
Examples of the optical element include an optical filter such as a polarizing filter, a compound lens such as an optical pickup, a prism, a diffraction grating, and the like in addition to the wave plate.
As mentioned above, although the manufacturing method and optical element of the optical element of this invention were demonstrated based on embodiment of illustration, this invention is not limited to these.

For example, the optical element manufacturing method of the present invention may be any one or a combination of two or more of the above embodiments.
Moreover, in the method for manufacturing an optical element of the present invention, one or more optional steps may be added as necessary.
In each of the above embodiments, the method of joining two optical components, the first optical component and the second optical component, has been described. However, when three or more optical components are joined, You may make it use the manufacturing method of an optical element.

Next, specific examples of the present invention will be described.
1. Production of Laminated Optical Element In the following, a plurality of laminated optical elements were produced in each of Examples, Reference Examples and Comparative Examples.
(Example)
First, a quartz substrate having a length of 20 mm × width 20 mm × an average thickness of 2 mm was prepared as a first optical component, and a crystal substrate having a length of 20 mm × width 20 mm × an average thickness of 1 mm was prepared as a second optical component. . Note that these quartz substrates are all subjected to optical polishing.
Next, each substrate was accommodated in the chamber 101 of the plasma polymerization apparatus 100 shown in FIG. 5, and surface treatment with oxygen plasma was performed.
Next, a plasma polymerization film having an average thickness of 200 nm was formed on the surface subjected to the surface treatment. The film forming conditions are as shown below.

<Film formation conditions>
-Source gas composition: Octamethyltrisiloxane-Source gas flow rate: 50 sccm
Carrier gas composition: Argon Carrier gas flow rate: 100 sccm
・ High frequency power output: 100W
・ High frequency output density: 25 W / cm ²
-Chamber pressure: 1 Pa (low vacuum)
・ Processing time: 15 minutes ・ Substrate temperature: 20 ° C.
Thereby, a plasma polymerization film was formed on each substrate.

The plasma polymerized film thus formed is composed of a polymer of octamethyltrisiloxane (raw material gas), and includes a Si skeleton including a siloxane bond and a random atomic structure, and an alkyl group (desorbed). Group). Further, the crystallinity of the plasma polymerized film was measured by an infrared absorption method. As a result, the degree of crystallinity of the plasma polymerized film was in the range of 5 to 30% although there was some variation depending on the measurement location.
Next, plasma treatment was performed on the edge of each obtained plasma polymerization film under atmospheric pressure. Note that argon gas was used as a processing gas in the plasma processing.
Next, the effective diameter of the obtained plasma polymerization film was irradiated with ultraviolet rays under the following conditions.

<Ultraviolet irradiation conditions>
・ Composition of atmosphere: Nitrogen atmosphere (dew point: -20 ° C)
・ Atmosphere temperature: 20 ℃
・ Atmospheric pressure: Atmospheric pressure (100 kPa)
UV wavelength: 172 nm
-Integrated light quantity of ultraviolet rays: 10 J / cm ²
Next, one minute after applying the plasma treatment, the respective substrates were overlapped so that the plasma polymerization films were in contact with each other. Thereby, a laminated optical element was obtained.

(Reference example)
A laminated optical element was obtained in the same manner as in the above example except that the irradiation of ultraviolet rays was omitted and the entire plasma polymerized film was exposed to plasma.
(Comparative example)
A laminated optical element was obtained in the same manner as in the above example, except that the first optical component and the second optical component were bonded using an epoxy-based optical adhesive.

2. 2. Evaluation of Laminated Optical Element 2.1 Evaluation of Bonding Strength (Split Strength) For the laminated optical elements obtained in Examples, Reference Examples and Comparative Examples, the bonding strength was measured.
The bonding strength was measured by measuring the strength immediately before peeling off each substrate. Further, the measurement of the bonding strength was performed immediately after bonding and after repeating the temperature cycle of −40 ° C. to 125 ° C. 100 times after bonding.
As a result, the laminated optical elements obtained in Examples and Reference Examples had sufficient bonding strength both immediately after bonding and after temperature cycling.
On the other hand, the laminated optical element obtained in the comparative example had a sufficient bonding strength immediately after bonding, but the bonding strength decreased after the temperature cycle.

2.2 Evaluation of dimensional accuracy The dimensional accuracy (parallelism) in the thickness direction was measured for each of the laminated optical elements obtained in Examples, Reference Examples and Comparative Examples.
Specifically, the thickness of the four corners of the laminated optical element was measured with a micro gauge. And the relative inclination of both surfaces of a laminated optical element was computed based on the difference of the thickness of four corners.
As a result, the laminated optical elements obtained in Examples and Reference Examples had a parallelism of ± 1 second or less, and the variation in the parallelism between the laminated optical elements was small.
On the other hand, the laminated optical element obtained in the comparative example had a parallelism of ± 1 second or more, and the variation in the parallelism was large among a plurality of laminated optical elements.

2.3 Evaluation of light transmittance The light transmittance (wavelength of 405 nm) in the thickness direction of each of the laminated optical elements obtained in Examples, Reference Examples and Comparative Examples was measured. The light transmittance was measured after irradiating light with a wavelength of 405 nm and an output of 100 mW continuously in a 70 ° C. environment for 1000 hours and 3000 hours, respectively. Then, the measured light transmittance was evaluated according to the following evaluation criteria.

<Evaluation criteria for light transmittance>
A: Light transmittance is 99.0% or more B: Light transmittance is 98.0% or more and less than 99.0% Δ: Light transmittance is 97.0% or more and less than 98.0% ×: Light transmittance is 97 Less than 0.0% The light transmittance evaluation results are shown in Table 1.

  As is clear from Table 1, the laminated optical elements obtained in the examples and reference examples had a light transmittance of 98% or more and good light transmittance. On the other hand, the laminated optical element obtained in the comparative example had sufficient light transmittance immediately after the start of light transmission, but after 1000 hours and 3000 hours, the light transmittance became less than 97%, and the light transmittance Had fallen.

2.4 Appearance Evaluation After evaluating the light transmittance of 2.3 for the laminated optical elements obtained in Examples, Reference Examples and Comparative Examples, the appearance of the irradiated part was evaluated according to the following evaluation criteria. .
<Evaluation criteria for appearance>
◎: No yellowing or foreign matter is observed at the joining interface ○: Yellowing or slight foreign matter is observed at the joining interface △: Many yellow spots or foreign matters are observed at the joining interface ×: Layered at the joining interface Table 1 shows the results of external appearance evaluation.
As is apparent from Table 1, in the laminated optical elements obtained in the examples and reference examples, no foreign matter or yellowing was observed at the bonding interface. On the other hand, the laminated optical element obtained in the comparative example was yellowed over a wide range after evaluating 2.3.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view (longitudinal sectional view) for explaining a first embodiment of a method for producing an optical element of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view (longitudinal sectional view) for explaining a first embodiment of a method for producing an optical element of the present invention. In the manufacturing method of the optical element of this invention, it is the elements on larger scale which show the state before energy provision of a joining film | membrane. In the manufacturing method of the optical element of this invention, it is the elements on larger scale which show the state after the energy provision of a joining film | membrane. It is a longitudinal cross-sectional view which shows typically the plasma polymerization apparatus used for the manufacturing method of the optical element of this invention. It is a figure (longitudinal sectional view) for demonstrating the method of producing a joining film | membrane on the 1st optical component. It is a figure (longitudinal sectional view) for demonstrating 2nd Embodiment of the manufacturing method of the optical element of this invention. It is a perspective view which shows the wavelength plate (optical element) obtained by applying the optical element of this invention.

Explanation of symbols

  2... First optical component 25... Upper surface 3, 31, 32... Bonding film 3a... Effective diameter (effective area) 3b .. Edge (ineffective area) 301. …… Leaving group 304 ...... Active hand 35, 351, 352 …… Surface 4 …… Second optical component 5, 5a …… Laminated optical element 6, 7 …… Mask 61, 71 …… Window portion 100 …… Plasma polymerization apparatus 101 ... Chamber 102 ... Ground wire 103 ... Supply port 104 ... Exhaust port 130 ... First electrode 139 ... Electrostatic chuck 170 ... Pump 171 ... Pressure control mechanism 180 ... Power supply circuit 182 …… High frequency power supply 183 …… Matching box 184 …… Wiring 190 …… Gas supply unit 191 …… Liquid storage unit 192 …… Vaporizer 193 …… Gas cylinder 194 …… Tube 195 ...... diffusion plate 9 ...... wavelength plates 91 and 92 ...... crystal plate

Claims (27)

A first optical component and a second optical component that can form an optical element by bonding to each other through a bonding film are prepared, and siloxane (Si--) is formed on the surface of the first optical component by plasma polymerization. O) a first step of forming the bonding film including a Si skeleton having a random atomic structure including a bond and a leaving group bonded to the Si skeleton;
By irradiating the effective optical region of the optical element with ultraviolet rays in the bonding film, most of the leaving groups present in the effective region are desorbed from the Si skeleton, and the effective region is While chemically stabilizing, by giving energy to an ineffective region other than the effective region of the bonding film, the leaving group present on the surface of the ineffective region is desorbed from the Si skeleton, A second step of developing adhesiveness;
A third step of bonding the first optical component and the second optical component via the bonding film exhibiting adhesiveness to obtain the optical element; Method.   2. The optical element according to claim 1, wherein the total of the Si atom content and the O atom content is 10 to 90 atom% among atoms obtained by removing H atoms from all atoms constituting the bonding film. Method.   The method for manufacturing an optical element according to claim 1, wherein the abundance ratio of Si atoms to O atoms in the bonding film is 3: 7 to 7: 3.   4. The method of manufacturing an optical element according to claim 1, wherein the crystallinity of the Si skeleton is 45% or less.   The method for manufacturing an optical element according to claim 1, wherein the bonding film includes a Si—H bond.   In the infrared light absorption spectrum of the bonding film including the Si—H bond, when the peak intensity attributed to the siloxane bond is 1, the peak intensity attributed to the Si—H bond is 0.001 to 0.2. The method for manufacturing an optical element according to claim 5.   The leaving group includes an H atom, a B atom, a C atom, an N atom, an O atom, a P atom, an S atom, and a halogen atom, or an atomic group arranged so that each of these atoms is bonded to the Si skeleton. The method for manufacturing an optical element according to claim 1, wherein the optical element is made of at least one selected from the group consisting of:   The method for producing an optical element according to claim 7, wherein the leaving group is an alkyl group.   In the infrared light absorption spectrum of the bonding film containing a methyl group as the leaving group, when the peak intensity attributed to the siloxane bond is 1, the peak intensity attributed to the methyl group is 0.05 to 0.45. The manufacturing method of the optical element of Claim 8.   The method for manufacturing an optical element according to claim 1, wherein the bonding film has an active hand after the leaving group existing at least near the surface thereof is detached from the Si skeleton.   The method of manufacturing an optical element according to claim 10, wherein the active hand is a dangling hand or a hydroxyl group.   The method for manufacturing an optical element according to claim 1, wherein the bonding film is made of polyorganosiloxane as a main material.   The method for producing an optical element according to claim 12, wherein the polyorganosiloxane is mainly composed of a polymer of octamethyltrisiloxane. Wherein the plasma polymerization method, the power density of the high frequency at the time of generating plasma, method of manufacturing an optical element according to any one of claims 1 a 0.01~100W / cm ² 13.   The method for manufacturing an optical element according to claim 1, wherein an average thickness of the bonding film is 1-1000 nm.   The method of manufacturing an optical element according to claim 1, wherein the bonding film is a solid having no fluidity.   The method of manufacturing an optical element according to claim 1, wherein a refractive index of the bonding film after the ultraviolet irradiation of the effective region is 1.35 to 1.6.   The method of manufacturing an optical element according to claim 1, wherein the invalid area of the bonding film is set at an edge of the optical element.   The method for manufacturing an optical element according to claim 1, wherein the effective region of the bonding film after the second step is configured using silicon oxide as a main material.   The method of manufacturing an optical element according to claim 1, wherein the wavelength of the ultraviolet light in the second step is 126 to 300 nm. 21. The method of manufacturing an optical element according to claim 1, wherein an integrated light amount of ultraviolet rays in the second step is 1 J / cm ² or more.   The method of manufacturing an optical element according to any one of claims 1 to 21, wherein in the second step, an atmosphere in which the bonding film is irradiated with ultraviolet rays is a dry atmosphere.   23. The method of manufacturing an optical element according to claim 1, wherein in the second step, an atmosphere in which the bonding film is irradiated with ultraviolet rays is an inert gas atmosphere or a reduced pressure atmosphere.   24. The method of manufacturing an optical element according to claim 1, wherein the first optical component and the second optical component are each made of quartz glass or quartz. The application of the energy is performed by a method of exposing the bonding film to plasma,
The method of manufacturing an optical element according to any one of claims 1 to 24, wherein the plasma is atmospheric pressure plasma. In the first step, a bonding film similar to the bonding film is formed on the surface of the second optical component,
In the second step, after each of the bonding films is irradiated with ultraviolet rays, in the third step, the bonding films are brought into close contact with each other so that the first optical component and the second optical component are in contact with each other. The method for manufacturing an optical element according to claim 1, wherein the optical element is obtained by bonding the two.   27. An optical element comprising two optical components, which are bonded together by the method for manufacturing an optical element according to any one of claims 1 to 26.

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