JP2003012349A - Joining optical element for use in uv region - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joining optical element for use in UV region having high light transmittance in UV region and good adhesion durability in the joining state of the optical element, where the adhesive can be cured in a short time under normal temperature. SOLUTION: This joining optical element for use in UV region is formed by joining optical elements 1 and 2 which transmit UV light through an adhesive layer 3. As the adhesive layer 3, a solution in which a solvent-soluble type organic fluoropolymer with no unsaturated bond in the molecule is dissolved in a fluorine-containing solvent having >=150 deg.C boiling point and no unsaturated bond in the molecule is used. The solvent in a part in contact with atmosphere is vaporized and the optical element is joined in the state in which the solvent in other part is left remaining.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cemented optical element used in a transmission optical system such as a cemented lens and a cemented prism in which two or more optical elements are cemented, and particularly to an objective lens of an ultraviolet region microscope. The present invention relates to a joining optical element for the ultraviolet region used in the ultraviolet region.

[0002]

2. Description of the Related Art Balsam, epoxy-based or acrylate-based UV-curing adhesives are used for joining optical elements used in transmission optical systems. This is because the optical system used up to now has been treated mainly as being used in the visible light region (wavelength of 400 nm or more), so the light transmittance of the adhesive used is only in the visible light region. is there.

However, recently, in the field of optical technology, higher precision resolution is required, and therefore a transmission optical system using ultraviolet rays having a short wavelength is desired. As an ultraviolet cemented lens used in such a transmission optical system, Japanese Patent Application Laid-Open No. 10-142498 discloses an objective lens using a large number of cemented lenses of a quartz lens and a fluorite lens. However, when joining the lenses,
When the adhesive used for bonding in the visible light region is used, since the light transmittance in the ultraviolet region (wavelength 200 to 400 nm) is not high, the bonding layer absorbs the light in the ultraviolet region and transmits it. The amount of light that can be produced is extremely reduced.
For this reason, it cannot be used in an optical system targeting a region having a wavelength of 350 nm or less.

On the other hand, in Japanese Patent No. 2786996, a cemented optical element that can be used even in the ultraviolet range is obtained by using silicone alcoholate as an adhesive and hydrolyzing this to bond optical elements. Is proposed.

Further, Japanese Unexamined Patent Publication No. 9-80207 discloses that
There has been proposed an optical lens for an ultraviolet irradiation device in which a bonding film of a bonding optical element is coated with a dielectric film and then bonded with an ultraviolet curable adhesive.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
As described in Japanese Patent No. 786996, a cemented optical element using a silicone alcoholate transmits ultraviolet rays, but
Since the adhesive is hydrolyzed and cured, it is necessary to supply water for curing to the bonding layer. Also,
In the case where the lens and the prism are in the joined state, there is a problem that the water supply is insufficient and it takes a very long time (several days) to cure.

Further, in this cemented optical element, since the curing form is a dehydration condensation reaction, curing shrinkage occurs during curing, peeling occurs at the interface between the optical element and the adhesive, or the adhesive layer is fragile and cracks. And the problem of causing optical distortion.

Further, even if the film initially has a high transmittance in the ultraviolet range, if the light in the ultraviolet range continues to be transmitted for a long time, the molecules of the adhesive gradually undergo cleavage or depolymerization. For example, it deteriorates and becomes a state of peeling or emitting fluorescence. Therefore, there is also a problem that the initial performance cannot be maintained for a long time.

On the other hand, in the case where a dielectric film is coated on the bonding interface and bonding is performed with an ultraviolet curable adhesive as in JP-A-9-80207, most effects are observed in the short wavelength region of 300 nm or less. Not only that, but also the UV-curable adhesive is prone to deterioration due to UV rays in this region and emits fluorescence, which causes a problem that it cannot withstand long-term use.

The present invention has been made in view of such conventional problems, and an object thereof is to cure an adhesive in a short time even in a low temperature range such as normal temperature, and Optical elements can be easily and reliably joined without needing them, and they have excellent adhesive durability with very little occurrence of interface peeling / scratching, adhesive layer cracks or optical distortion in the joined state, and in the ultraviolet range. It is an object of the present invention to provide a bonding optical element for the ultraviolet region, which has a high transmittance and is hardly deteriorated in the transmittance in the ultraviolet region even by long-term irradiation with high-energy ultraviolet light.

Another object of the present invention is that the bonding state of the entire molecule of the organic fluororesin is firmly stabilized, and even if it is irradiated with high energy of ultraviolet rays for a long period of time, it is mechanically and optically deteriorated and bonded. It is an object of the present invention to provide a joining optical element for the ultraviolet region, which can maintain a good condition.

A further object of the present invention is to provide a junction optical element for the ultraviolet region, which can facilitate uniform film thickness control, reduce variations in the transmittance, and have excellent transmittance in the ultraviolet region.

[0013]

In order to achieve the above object, the joining optical element for ultraviolet region according to the invention of claim 1 is a joining device for ultraviolet region in which an optical element transmitting ultraviolet rays is joined through an adhesive layer. In the optical element, the adhesive is a solution prepared by dissolving a solvent-soluble organic fluororesin having no unsaturated bond in the molecule in a fluorine-containing solvent having no unsaturated bond in the molecule and a boiling point of 150 ° C. or more. The optical element is used as a layer, and the optical element is bonded in a state where the solvent in the portion where the adhesive layer is in contact with the atmosphere is volatilized and the solvent in the other portion is left in the adhesive layer.

The organic fluororesin used in the present invention has no unsaturated bond in the molecule. The carbon-fluorine bond energy of the organic fluororesin is 107 kcal /
mol, and the carbon-carbon bond energy is 83.1.
kcal / mol, carbon-hydrogen bond energy 9
8.8 kcal / mol, carbon-oxygen bond energy 84.0 kcal / mol, carbon-nitrogen bond energy 69.7 kcal / mol, carbon-chlorine bond energy 78.5 kcal / mol, etc.,
It has a very strong bond. In addition, the bond energy between carbon and carbon linked to carbon and fluorine is reinforced by fluorine, and therefore the organic fluororesin is a resin that is electrically, chemically and thermally stable. .

Further, since the organic fluororesin is a resin material having high heat resistance and forms a relatively flexible film, even if stress is generated, the stress can be absorbed by the flexibility of the adhesive layer, and the optical strain Can be reduced.

On the other hand, the organic fluororesin is provided with a functional group such as a vinyl group or an acryloyl group in order to have reactivity with other materials, or in order to impart solubility in a solvent, Some of them have a phenyl group, a carbonyl group, a carboxyl group, a cyano group, a triazine ring structure, etc., and the structure having such an unsaturated bond is easily excited by ultraviolet rays to cause depolymerization or emit fluorescence. However, it is not suitable for joining optical elements for the ultraviolet region. For this reason, the adhesive layer in the present invention does not use an organic fluororesin having a structure having an unsaturated bond.

Such an organic fluororesin having no unsaturated bond does not cause depolymerization or the like by being excited by ultraviolet rays and does not emit fluorescence, has transparency even in an ultraviolet region, and has a long-term transparency. Since it does not deteriorate even when irradiated with ultraviolet rays, it can be used as an adhesive layer between optical elements for the ultraviolet region.

As a solvent-soluble organic fluororesin having no unsaturated bond in the molecule, polyvinylidene fluoride (P
VdF), fluoroolefin vinyl ether copolymer, and the like, those having a polar group such as an ether group, a hydroxyl group, and an epoxy group (having a function of facilitating dissolution of a resin in a solvent), or a fluorine-containing ring structure such as a fluoroaliphatic ether ring Some have. In addition, there is also one in which impurities (for example, dust or ionic impurities) are removed from these organic fluororesins having no unsaturated bond to raise the grade. These have high transparency even in the ultraviolet region, are resistant to deterioration by long-term irradiation with ultraviolet rays, and have stable optical characteristics.

The solvent for dissolving the organic fluororesin is a fluorine-containing solvent having no unsaturated bond in the molecule and having a boiling point of 150 ° C. or higher, for example, a perfluoro compound or perfluorotributylamine as a main component. These can be used alone or as a mixture, but it is essential that at least the organic fluororesin to be applied can be dissolved. Such a solvent firmly stabilizes the bonding state of the entire molecule even if it remains in the adhesive layer of the cemented optical element,
Even if the high energy of ultraviolet rays is irradiated for a long period of time, a good bonding state can be maintained without mechanical or optical deterioration. On the other hand, when a solvent having a boiling point of less than 150 ° C. is used, shrinkage of the adhesive layer occurs along with volatilization of the solvent, and as the internal stress increases due to this shrinkage, scratches occur around the optical element after joining, It cannot be used as an optical element.

A solution prepared by dissolving a solvent-soluble organic fluororesin in a solvent easily wets the surface of the optical element. This organic fluororesin solution is supplied between the optical elements to wet the entire surface of the optical elements, and then the solvent in the part where the adhesive layer contacts the atmosphere is volatilized at room temperature in a short time and transported to the next step. To do. This eliminates the need to hold and fix the optical elements while positioning the optical elements to be joined until the solvent of the organic fluororesin solution is completely volatilized and removed from the adhesive layer. Greatly improves efficiency.

In such a cemented optical element, a step of dissolving an organic fluororesin as an adhesive layer in a solvent, and a step of wetting and spreading the entire surface of the optical element to be joined without mixing defects such as bubbles. While the adhesive is fluidizing, the steps of aligning the optical elements to be bonded (centering) while controlling the thickness of the adhesive layer and the steps of aligning the optical elements to be bonded with each other are performed. , A process of removing the excess adhesive that has overflowed, and a process of holding and fixing the optical element to be joined. Further, in order to efficiently carry out these steps, a device for bonding while controlling the thickness of the adhesive layer, a positional deviation in the solvent volatilization process and an adhesive agent while positioning the optical elements to be bonded together. A device or the like is used that holds and fixes the layer while preventing it from breaking and mixing of air bubbles. The holding and fixing of the optical elements to be bonded with each other positioned is performed by volatilizing the solvent of the portion of the adhesive layer that is in contact with the atmosphere after removing the protruding portion.

According to a second aspect of the present invention, there is provided the ultraviolet bonding optical element according to the first aspect, wherein the organic fluororesin comprises:
It is characterized by having a structure having only four atoms of a carbon atom, a fluorine atom, an oxygen atom and a hydrogen atom in the molecule.

In the present invention, in addition to the fact that the organic fluororesin used for the adhesive layer has no unsaturated bond in the molecule,
Since the structure consists of only 4 atoms of carbon atom, fluorine atom, oxygen atom and hydrogen atom, the bonding state of the whole molecule is firmly stabilized, and even if high energy of ultraviolet rays is irradiated for a long period of time, mechanical and optical Without deterioration
The joined state can be maintained well.

A third aspect of the present invention is the junction optical element for the ultraviolet region according to the first or second aspect, wherein the organic fluororesin has a fluorine-containing aliphatic ether ring structure in the main chain. .

Such an organic fluororesin is easily soluble in a specific solvent such as a solvent composed of a perfluoro compound such as perfluorobenzene, perfluoro (2-butyltetrahydrofuran), perfluorotributylamine and a hydrofluoroether compound. Therefore, it is possible to wet the surfaces of the optical elements to be bonded without mixing defects such as bubbles, and it is possible to easily control the uniform film thickness and reduce variations in transmittance. Further, since it is amorphous, it has an advantage that it has excellent transmittance in the ultraviolet region.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) The junction optical element for the ultraviolet region of this embodiment is composed of a bonded prism as shown in FIG. This prism is formed by joining a quartz prism having a high transmittance of ultraviolet rays, and the quartz prism 1 and the quartz prism 2 having a half mirror coating 2a made of an Ag layer on the joining surface are made of an organic fluororesin. Are bonded by an adhesive layer 3. The spectral transmittance and spectral reflectance of the bonded prism are set to 55% and 45%, respectively, by design.

The organic fluororesin used as the adhesive layer in this embodiment has only carbon atoms, fluorine atoms, hydrogen atoms and oxygen atoms in its molecule, and has a fluorine-containing aliphatic ether ring structure in its main chain. Perfluoro (2,2-dimethyl-
It is an amorphous polymer of 1,3-dioxole). Then, a solution obtained by dissolving about 5 wt% of this organic fluororesin in a perfluoro-containing compound solvent consisting of tris (perfluorobutyl) amine (boiling point 174 ° C.) as a fluorine-containing solvent is used as an adhesive. A coupling agent may be mixed in an amount of about 0.5 wt% in order to enhance the adhesion between the prisms 1 and 2 and the adhesive layer 3.

In order to manufacture the junction optical element for the ultraviolet region of this embodiment, first, the above-mentioned organic fluororesin solution is dropped on the half mirror coating 2a on the joint surface of the quartz prism 2, and another one is further formed thereon. One quartz prism 1
The adhesive solution 3 is thinned by spreading the resin solution on each joint surface while removing air bubbles by pressing. At this time, the adhesive excessively protruding from the joint surface is removed before the solvent volatilizes and solidifies.

After positioning the quartz prism 2 and the other quartz prism 1, the positions are fixed with a jig, and the adhesive layer is exposed to the atmosphere for about 40 minutes at room temperature with light pressure applied. It is left until the solvent (see FIG. 1 (b)) in the contacting portion 10 is completely removed by spontaneous volatilization, and the prisms 1 and 2 are cemented to form an ultraviolet region cemented optical element. At this time, the thickness of the adhesive layer 3 was 5 μm.

Acceleration test for measuring the spectral transmittance of this joining optical element for the ultraviolet region and then conducting durability test of the half mirror by irradiation of ultraviolet rays (continuous irradiation with ultraviolet ray wavelength 248 nm, output ² mW / cm ² ). FIG. 2 shows the results of measuring the spectral transmittance again after being put in the glass for 4 months. In FIG. 2, the solid line A indicates before the accelerated test, and the broken line B indicates after the accelerated test.

As is clear from the results shown in FIG.
At 0 nm or less, the transmittance after the accelerated test is lower than that before the accelerated test, but in the wavelength range of 270 nm to 400 nm, the transmittance in the ultraviolet region is good, there is almost no absorption in the adhesive layer, and the long-term It can be seen that the characteristics are hardly deteriorated even by irradiation with ultraviolet rays. Further, it can be used because it transmits light even in a wavelength range of 200 nm to 270 nm. Further, in the optical element after the accelerated test, peeling / scratch on the bonding surface and cracks in the adhesive layer were not found.

The transmittance characteristics of such a joining optical element for the ultraviolet region satisfy the optical characteristics required for use in the ultraviolet region such as a beam splitter of an ultraviolet irradiation system in an ultraviolet microscope, Since it also has heat resistance to withstand the heat (estimated temperature of 120 ° C. or higher) generated by the irradiation of the ultraviolet ray, it can be sufficiently used in the same application.

As described above, according to the junction optical element for the ultraviolet region of this embodiment, the ultraviolet region (wavelength 200 n
m-400 nm) shows high transmittance, and even though it is a solvent-containing adhesive, the adhesive layer can be cured in a short time, and peeling and cracking of the interface in the bonded state and cracks of the adhesive layer occur. In addition, it is possible to maintain the transmittance in the ultraviolet region having a wavelength of 200 nm or more for a long time.

In the present embodiment, the solvent in the portion where the adhesive layer contacts the atmosphere is removed by spontaneous volatilization.
In the case of joining the same kind of material as in this embodiment, the solvent in the adhesive layer may be promoted to volatilize the solvent under a heating atmosphere to such an extent that the solvent in the adhesive layer is not completely removed. This makes it possible to further improve workability and adhesive strength.

(Embodiment 2) FIG. 3 shows a joining optical element for ultraviolet region according to a second embodiment, in which a quartz lens 4 and a fluorite lens 5 are joined via an adhesive layer 6 made of an organic fluororesin. It is a cemented lens manufactured by the above.

The organic fluororesin used in this embodiment is a perfluoro (2,2-) resin having a fluorine-containing aliphatic ether ring structure similar to that used in Embodiment 1 in the main chain.
It is an amorphous polymer of dimethyl-1,3-dioxole). A solution prepared by dissolving about 5 wt% of this organic fluororesin in a solvent containing a perfluoro compound containing tris (perfluorobutyl) amine as a fluorine-containing solvent is used as an adhesive. In order to improve the adhesiveness between the lenses 4 and 5 and the adhesive layer 6, a coupling agent is added in an amount of 0.
You may mix about 5 wt%.

In order to manufacture the cemented optical element for the ultraviolet ray region of this embodiment, first, the above-mentioned organic fluororesin solution is dropped on the cemented surface of the quartz lens 4, and the fluorite lens 5 is placed on it. The adhesive layer 6 is thinned by spreading the resin solution on each joint surface while applying pressure to remove bubbles. Further, the adhesive that excessively protrudes from the joint surface is removed before the solvent volatilizes and solidifies.

Then, after the optical cores of the quartz lens 4 and the fluorite lens 5 are taken out and aligned with each other, the positions are fixed by a jig, and while being lightly pressed, the adhesive layer is kept at room temperature for about 40 minutes. 6 is a solvent in a portion 11 in contact with the atmosphere (Fig. 3 (b))
(See) is left until it completely disappears due to spontaneous volatilization, to obtain a cemented optical element for the ultraviolet region in which the lenses 4 and 5 are cemented. At this time, the thickness of the adhesive layer 6 is about 5 μm.
m, and the solvent in the adhesive layer 6 remains without being removed.

Using the junction optical element for ultraviolet region of this embodiment, an ultraviolet irradiation acceleration test was carried out in the same manner as in Embodiment 1, and the spectral transmittance in the ultraviolet region before and after the test was measured. FIG. 4 shows the measurement results, where the solid line C is before the accelerated test and the broken line D is after the accelerated test.

As is clear from the results shown in FIG.
When the thickness is 0 nm or less, the transmittance after the accelerated test is somewhat lower than that before the accelerated test, but in the wavelength range of 240 nm to 400 nm, the transmittance in the ultraviolet region is 90% or more, which is good. The absorption of is extremely low. Further, it can be seen that the characteristics are hardly deteriorated even after long-term irradiation with ultraviolet rays. Furthermore, in the optical element after the accelerated test, neither peeling nor cracking on the joint surface nor cracks in the adhesive layer were found.

The transmittance characteristic of such a cemented optical element for the ultraviolet region is the same as the cemented lens in the objective lens system of the ultraviolet microscope, the cemented optical system of various devices applying the excimer laser, and the similar applications. It can be fully used in.

According to the joining optical element for the ultraviolet region of this embodiment, a high transmittance is exhibited in the ultraviolet region, and when the adhesive layer is cured, it is a solvent-containing adhesive, but no heating equipment is required. It can be done reliably in a short time at normal room temperature. In addition, there is no peeling or cracking of the interface or cracks in the adhesive layer in the bonded state, and it becomes possible to maintain the transmittance in the ultraviolet region of wavelength 200 nm or more for a long period of time.

(Embodiment 3) The junction optical element for the ultraviolet region of this embodiment is the bonded prism shown in FIG. 1, and is the perfluoro (2,2-) used in Embodiment 1.
An amorphous polymer of dimethyl-1,3-dioxole) was replaced with a solution prepared by dissolving about 5 wt% of a perfluoro compound-containing solvent consisting of tris (perfluorobutyl) amine in a non-organic fluororesin. Crystalline perfluoro (2,2-dimethyl-1,3-dioxolane) / tetrafluoroethylene copolymer is a commercially available perfluoro-containing compound solvent as a fluorinated solvent, trade name “Fluorinert ™ FC- 70 "(boiling point 215 ° C) and trade name" Fluorinert TM FC-43 "(boiling point 174
A solution prepared by dissolving about 5 wt% in a solvent prepared by mixing 1 ° C.) at a ratio of 1: 1 was used as an adhesive. The manufacturing process is the first embodiment.
Is the same as. In this embodiment, the adhesive layer 3
Was left for about 2 hours until the solvent in the portion 10 in contact with the atmosphere was completely removed by spontaneous volatilization. Perfluoro (2,2-dimethyl-
The 1,3-dioxolane) / tetrafluoroethylene copolymer has only four atoms of carbon atom, fluorine atom, hydrogen atom and oxygen atom in its molecule. The spectral transmittance and the spectral reflectance of the bonded prism are designed to be 55% and 45%, respectively.

FIG. 5 shows the results of measuring the spectral transmittance in the ultraviolet region before and after the test, in which the ultraviolet ray accelerating test was conducted on the cemented optical element for the ultraviolet region of this embodiment in the same manner as in the first embodiment. The solid line E is before the accelerated test and the broken line F is after the accelerated test.

As is apparent from FIG. 5, the wavelength is 260 nm.
Below, the transmittance after the accelerated test is lower than that before the accelerated test, but in the wavelength range of 260 nm to 400 nm, the transmittance in the ultraviolet region is good, and the absorption in the adhesive layer is extremely small. . Further, it can be seen that the characteristics are hardly deteriorated even after long-term irradiation with ultraviolet rays. Further, it can be used because it transmits light even in a wavelength range of 200 nm to 260 nm. Furthermore, in the optical element after the accelerated test, neither peeling nor cracking on the joint surface nor cracks in the adhesive layer were found.

As described above, according to this embodiment, a high transmittance is exhibited in the ultraviolet region (wavelength 200 nm to 400 nm), and the adhesive layer can be easily and surely cured in a short time.
In the joined state, there is no peeling or cracking of the interface or cracks in the adhesive layer, and it is possible to maintain the transmittance in the ultraviolet region with a wavelength of 200 nm or more for a long period of time.

(Embodiment 4) The cemented optical element for ultraviolet region of this embodiment is the cemented lens shown in FIG. 3, and the perfluoro (2, 2) used in Embodiment 2 is used.
An amorphous polymer of (2-dimethyl-1,3-dioxole) was used as an organic fluororesin instead of a solution prepared by dissolving about 5 wt% of a perfluoro compound-containing solvent containing tris (perfluorobutyl) amine. Amorphous perfluoro (2,2-dimethyl-1,3-dioxolane) / tetrafluoroethylene copolymer of Fluorinet TM FC, which is a commercially available perfluoro-compound solvent as a fluorinated solvent. -40 "(boiling point 155 ° C) and" Fluorinert TM FC-43 "(boiling point 174 ° C) 1: 1
A solution prepared by dissolving about 5 wt% in the solvent mixed with was used as an adhesive. The manufacturing process is the same as in the second embodiment. This perfluoro (2,2-dimethyl-1,3-dioxolane) / tetrafluoroethylene copolymer is
It has only 4 atoms of carbon atom, fluorine atom, hydrogen atom and oxygen atom in the molecule.

FIG. 6 shows the result of measuring the spectral transmittance in the ultraviolet region before and after the test of the ultraviolet ray accelerating test similar to that of the first embodiment on the junction optical element for the ultraviolet region of this embodiment. The solid line G is before the accelerated test, and the broken line H is after the accelerated test.

As is clear from FIG. 6, the wavelength is 240 nm.
In the following, the transmittance after the accelerated test is somewhat lower than that before the accelerated test, but in the wavelength range of 240 nm to 400 nm, the transmittance in the ultraviolet region is 90% or more, and the absorption in the adhesive layer is good. Is extremely low. Further, it can be seen that the characteristics are hardly deteriorated even after long-term irradiation with ultraviolet rays. Furthermore, in the optical element after the accelerated test, neither peeling nor cracking on the joint surface nor cracks in the adhesive layer were found.

Therefore, according to this embodiment, a high transmittance is exhibited in the ultraviolet region, and when the adhesive layer is cured, it can be surely performed at room temperature in a short time, so that heating equipment is not required. In addition, there is no peeling or cracking of the interface or cracks in the adhesive layer in the bonded state, and the wavelength is 200 for a long time.
It is possible to maintain the transmittance in the ultraviolet region of nm or more.

In the above Embodiments 1 to 4, the organic fluororesin has only four carbon atoms, fluorine atoms, oxygen atoms and hydrogen atoms in the molecule and has a fluorine-containing aliphatic ether ring structure as a main component. I use what I have in the chain,
The present invention is not limited to this, and any solvent-soluble organic fluororesin that does not have an unsaturated bond in the molecule has the same effect.

[0052]

According to the invention of claim 1, the curing of the adhesive is completed in a short time even in a low temperature range such as room temperature, and the adhesive can be easily and surely joined without the need for heating equipment and the like. It has excellent adhesive durability with minimal peeling / scratching of the interface, cracking of the adhesive layer, and optical distortion, and shows high transmittance in the ultraviolet region, and even in the ultraviolet region even when irradiated with high-energy ultraviolet rays for a long time. It is possible to provide a cemented optical element for the ultraviolet region whose transmittance is unlikely to deteriorate.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, the bonding state of the whole molecule of the organic fluororesin is firmly stabilized, and even if high energy of ultraviolet rays is irradiated for a long period of time, It is possible to provide a joining optical element for the ultraviolet region that can maintain the joining state without mechanical or optical deterioration.

According to the invention of claim 3, claims 1 and 2
In addition to the effect of the invention described above, uniform film thickness control can be facilitated, variation in transmittance can be reduced, and a junction optical element for ultraviolet region can be obtained which has excellent transmittance in ultraviolet region.

[Brief description of drawings]

1A and 1B show a junction optical element for an ultraviolet region according to Embodiments 1 and 3, where FIG. 1A is a front view thereof, and FIG. 1B is an enlarged sectional view of a K portion in FIG.

FIG. 2 is a characteristic diagram of the spectral reflectance of the ultraviolet bonding optical element according to the first embodiment.

3A and 3B show a junction optical element for an ultraviolet region according to Embodiments 2 and 4, where FIG. 3A is a front view thereof, and FIG. 3B is an enlarged sectional view of an L portion of FIG.

FIG. 4 is a characteristic diagram of the spectral reflectance of the ultraviolet bonding optical element according to the second embodiment.

FIG. 5 is a characteristic diagram of the spectral reflectance of the junction optical element for ultraviolet region according to the third embodiment.

FIG. 6 is a characteristic diagram of the spectral reflectance of the joining optical element for ultraviolet region according to the fourth embodiment.

[Explanation of symbols]

1,2 quartz prism 3 Adhesive layer 4 quartz lens 5 Fluorite lens 6 Adhesive layer 10,11 Area where the adhesive layer contacts the atmosphere

Continued front page    F-term (reference) 2H043 AE02                 4G061 AA02 BA12 CA02 CB04 CB16                       CD10 DA36 DA43                 4J040 DC091 DD051 EE021 GA03                       GA05 GA08 GA11 HB03 HB04                       HB14 HB43 HC03 JA02 KA23                       LA05 LA06 LA07

Claims (3)

[Claims] 1. In a bonding optical element for ultraviolet region, wherein an optical element transmitting ultraviolet rays is bonded via an adhesive layer, a solvent-soluble organic fluororesin having no unsaturated bond in the molecule is formed in the molecule. Boiling point not containing unsaturated bonds is 150 ° C
Using a solution dissolved in the above fluorine-containing solvent as the adhesive layer, in a state where the solvent in the portion where the adhesive layer is in contact with the atmosphere is volatilized and the solvent in the other portion is left in the adhesive layer. A junction optical element for an ultraviolet region, which is obtained by joining optical elements. 2. The junction optical element for the ultraviolet region according to claim 1, wherein the organic fluororesin has a structure having only four atoms of carbon atom, fluorine atom, oxygen atom and hydrogen atom in the molecule. . 3. The junction optical element for the ultraviolet region according to claim 1, wherein the organic fluororesin has a fluorine-containing aliphatic ether ring structure in its main chain.