JPH09292505A - Reflection mirror for high energy beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reflection mirror for high energy beams having high reflectance characteristics and high heat resistance and mechanical strength by forming a laminated body comprising high reflective index layers and low refractive index layers alternately laminated on a glass layer. SOLUTION: A glass layer 12 is formed on a substrate 11, and high refractive index layers 13 and low refractive index layers 14 are alternately deposited in plural layers to form a laminated body 15 on the glass layer 12. The substrate 11 is preferably made of a ceramic material such as Al2 O3 , AIN and SiC or a metal or its alloy such as W, Mo, Fe, Cu. The glass component to constitute the glass layer 12 is, for example, PbO-SiO2 -B2 O3 with addition of Al2 O3 , alkaline earth metals or alkali metals. As for the high refractive index layers 13, ZnS, TiO2 , CeO2 , etc., be used. As for the low refractive index layers 14, MgF2 , ThF2 , etc., can be used.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a reflector used for reflecting light rays. More specifically, the present invention relates to a reflecting mirror for reflecting a high energy beam such as a laser beam.

[0002]

2. Description of the Related Art In recent years, the fields of application of high energy beams such as laser beams have been increasing. In particular, the field of activity of laser processing machines is expanding to ultra-precision processing such as drilling, cutting, and welding. Such a laser operates a laser beam by bending a laser beam generated from a laser beam source by a reflector or a prism. Conventionally, as a reflecting mirror that reflects such a high-energy light beam, a mirror in which a dielectric is formed in multiple layers on a substrate formed of an appropriate material such as a metal or an alloy such as aluminum or quartz glass is known. The surface of the substrate is mirror-polished, and the dielectric is formed on the substrate by a method such as an evaporation method or a sputtering method. By forming multiple dielectric layers, multiple boundary surfaces can be provided,
The reflection efficiency of light can be increased by increasing the reflection of light rays on the boundary surface.

However, since a metal material such as aluminum has a property of causing an oxidation reaction, when used for a high energy light beam, the oxidation reaction is promoted by the temperature rise caused by the reflection of this light beam. Therefore, there is a problem that the dielectric layer is peeled off to lower the reflectance. Further, although quartz glass has good workability and is superior in oxidation resistance to aluminum, the thermal conductivity of quartz glass itself is low, and similarly, due to the temperature rise caused by reflection of high-energy rays, the dielectric material is There was a problem that the reflectance was lowered due to peeling of the layer or thermal deformation of the substrate. In order to solve these problems, there is known a reflecting mirror using a ceramic such as Si or SiC having a relatively high thermal conductivity as a substrate. By using such a substrate, a reflection mirror having high oxidation resistance and good heat resistance can be manufactured.

[0004]

However, Si is excellent in thermal conductivity, but mechanical strength is weaker than aluminum or quartz glass, so it can be used for mirror-polishing the surface and handling for forming the dielectric layer. There is a problem that it causes difficulty and cannot be used in a place where mechanical strength is required. Also,
SiC has a higher mechanical strength than Si and does not cause any trouble in Si, but has a problem that the workability in mirror polishing is inferior due to the increase in mechanical strength. That is, due to the difficulty of mirror-polishing, an excessive time is required as compared with the normal processing time for processing Si and the like, and because of the fact that it is a sintered body, it causes grain shedding during polishing and There is a problem that it is difficult to finish the flatness of accuracy. An object of the present invention is to provide a reflecting mirror for high energy rays having high reflectance characteristics, high heat resistance and mechanical strength.

[0005]

The invention according to claim 1 is
As shown in the enlarged view of FIG. 1, a glass layer 12 is formed on a substrate 11, and a laminated body 15 in which a high refractive index layer 13 and a low refractive index layer 14 are alternately laminated a plurality of times on the glass layer 12 is formed. It is the formed high-energy light ray reflection mirror 10. Base 11
Even if the surface is rough, the glass layer 12 smoothes it, and the surface of the laminate 15 formed on the glass layer becomes a mirror surface without distortion and has a high reflectance characteristic.

The invention according to claim 2 or 3 is the invention according to claim 1, wherein the substrate 11 is a ceramic such as Al ₂ O ₃ (alumina), AlN (aluminum nitride), or SiC (silicon carbide). , Or W (tungsten), Mo
It is characterized by being made of a metal such as (molybdenum), Fe (iron), Cu (copper) or an alloy thereof. The base 11 is made of ceramics or a high melting point metal so as to have high heat resistance.

The invention according to claim 4 is the invention according to claims 1 to 3
It is the invention which concerns on either, The glass layer 12 is 0.5 micrometer.
The high refractive index layer 13 is formed to have a thickness of 30 μm to 50 μm.
The low refractive index layer 14 is formed to a thickness of 60 nm to 300 nm, and the low refractive index layer 14 is formed to a thickness of 60 nm to 300 nm. The glass layer 12 is preferably formed with a thickness of 2 μm to 40 μm. The thickness of the glass layer 12 is 0.5 μm
If it is less than 50 μm, the surface smoothness of the substrate is not sufficient, and as a result, it becomes difficult to obtain a high reflectance, and if it exceeds 50 μm, the thermal conductivity of the entire substrate is extremely lowered.
Further, the high refractive index layer 13 and the low refractive index layer 14 are 30 nm to 150 nm and 6 nm depending on the use of the reflecting mirror for high energy rays.
It is preferable that each layer is formed to a thickness of 0 nm to 300 nm. If the thicknesses of the high refractive index layer 13 and the low refractive index layer 14 are out of the above ranges, sufficient reflectance cannot be obtained.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The substrate 11 of the present invention is a plate-shaped substrate as shown in FIG. The glass component constituting the glass layer 12 of the present invention is, for example, a PbO—SiO ₂ —B ₂ O ₃ system to which Al ₂ O ₃ , an alkaline earth metal, an alkali metal or the like is added. It is preferable that the glass layer 12 has a coefficient of thermal expansion close to that of the substrate, because defects such as cracks do not occur during the formation of the glass layer. For example, if the substrate is Al
_{When it is made of 2} O ₃ , the thermal expansion coefficient of the glass layer is preferably close to that of this substrate (6.8 ± 1.0) × 10 ⁻⁶ / ° C., and when the substrate is made of AlN, The coefficient of thermal expansion of the glass layer is close to that of this substrate (4.4.
It is preferably ± 1.0) × 10 ⁻⁶ / ° C. . The glass layer 12 is formed by mixing the above glass powder with a solvent to form a glass paste, coating the glass paste on the surface of a substrate by a method such as screen printing, spray coating, dip coating, spin coating, etc., drying, and then firing. It is formed by softening the glass.

The high refractive index layer 13 and the low refractive index layer 14 are formed on the glass layer 12 by a sputtering method, a vapor deposition method or the like. As the high refractive index layer 13, ZnS (zinc sulfide),
TiO ₂ (titanium dioxide), CeO ₂ (cerium dioxide)
Etc. are illustrated. ZnS and TiO ₂ form a fairly stiff and fairly durable film without absorption of light in the visible spectrum, while CeO ₂ forms a more chemically stable film. Further, as the low refractive index layer 14, MgF ₂
(Magnesium fluoride), ThF ₂ (thorium fluoride) and the like are exemplified. Similarly, MgF ₂ and ThF ₂ do not absorb light in the visible spectrum range and form an extremely hard and durable film.

Since the reflection of light rays mainly occurs at the boundary surface having the refractive index, the reflection loss due to absorption is hardly present in the reflection occurring at the boundary surfaces different from each other, and a very good reflecting surface can be obtained. Therefore, normally, the high refractive index layer 13 having relatively little light absorption and being chemically stable is formed on the low refractive index layer 14 which does not normally absorb light and is chemically stable and has a low refractive index. As a result, the reflection characteristic at the boundary surface can be improved, and the reflection efficiency can be improved by providing a plurality of such layers 13 and 14. However, it is necessary to select the film thickness of these layers 13 and 14 in consideration of the intended use. That is, the light reflected from the boundary surface between the layers 13 and 14 is reflected while overlapping each other, so that when the phases of the light overlap each other, the lights strengthen each other, and when the phases are reversed, the light cancels each other out. become. Therefore, the reflectivity can be increased by adjusting the film thickness according to the wavelength and the incident angle of the light beam to be reflected, and sequentially increasing the number of boundary surfaces by laminating a plurality of times. The laminated body 15 includes a high refractive index layer 13 and a low refractive index layer 1
It is preferable that at least two layers of 4 are formed.
If it is less than two layers, it will be difficult to obtain a sufficient reflectance.

[0011]

Next, embodiments of the present invention will be described. <Examples 1 to 7> As shown in FIG. 1, the substrate 11 of the high-energy ray reflecting mirror 10 has a thickness of 10 mm, and the reflecting surface of the substrate 11 has a surface roughness of the center line average roughness. 0.5
It is ground to ˜0.6 μm. The material of the substrate 11 is shown in Table 1. The glass layer 12 on the reflecting surface of the substrate 11 has a softening point of 750 ° C. over the entire reflecting surface of PbO—SiO ₂ —B ₂ O.
A paste containing ₃ type glass particles is applied by a spray coating method, and the substrate coated with this paste is applied to 150
It was dried at 10 ° C. for 10 minutes and then baked at 1000 ° C. for 10 minutes in the atmosphere to form a film having a thickness of about 4 μm. On the glass layer 12 of the substrate 11, a ZnS thin film having a high refractive index layer having a thickness of 60 nm and a MgF ₂ thin film having a low refractive index layer having a thickness of 100 nm are alternately laminated five times by a vacuum deposition method to form a laminate. Formed 15.

<Comparative Examples 1 to 7> For comparison, Comparative Examples 1 to 7 are the same as Examples 1 to 7 except that the glass layer is not formed.
The reflection mirror for high energy light of No. 7 was produced. <Comparative Test and Evaluation> With respect to the high-energy light ray reflecting mirrors of Examples 1 to 7 and Comparative Examples 1 to 7, the reflectance when the light having a wavelength of 550 nm was irradiated to the reflecting surface was measured using a spectrophotometer. It was measured. Table 1 shows the results.

[0013]

[Table 1]

As is clear from Table 1, the reflectances of Comparative Examples 1 to 7 having no glass layer were as low as 65 to 75%, whereas the reflectances of Examples 1 to 7 having the glass layer were 9%.
The value was as high as 7 to 98%.

[0015]

As described above, in the high-energy ray reflecting mirror of the present invention, even if the surface of the substrate is rough, the glass layer smoothes it. As a result, even if a sintered body such as ceramics is used for the substrate, the shedding points are compensated by the glass layer, and the surface of the laminated body formed on the glass layer can be a mirror surface without distortion, and the high reflectance can be obtained. The characteristics can be obtained. Further, since the laminated body is formed on the substrate through the glass layer, the degree of freedom in selecting the material of the substrate is increased, and the substrate is made of ceramics or a metal having a high melting point, so that it has high heat resistance and mechanical strength. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a perspective view and a cross-sectional view of a high-energy ray reflecting mirror of the present invention.

[Explanation of symbols]

 10 Reflection Mirror for High Energy Rays 11 Substrate (Base) 12 Glass Layer 13 High Refractive Index Layer 14 Low Refractive Index Layer 15 Laminate

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[Procedure amendment]

[Submission date] May 24, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

The invention according to claim 4 is the invention according to claims 1 to 3
It is the invention which concerns on either, The glass layer 12 is 0.5 micrometer.
The high refractive index layer 13 is formed to have a thickness of m to 20 μm.
The low refractive index layer 14 is formed to a thickness of 60 nm to 300 nm, and the low refractive index layer 14 is formed to a thickness of 60 nm to 300 nm. The glass layer 12 is preferably formed with a thickness of 2 μm to 10 μm. The thickness of the glass layer 12 is 0.5 μm
If it is less than 20 μm, the surface smoothness of the substrate is not sufficient, and as a result, it becomes difficult to obtain a high reflectance, and if it exceeds 20 μm, there is a problem that the thermal conductivity of the entire substrate is extremely lowered.
Further, the high refractive index layer 13 and the low refractive index layer 14 are 30 nm to 150 nm and 6 nm depending on the use of the reflecting mirror for high energy rays.
It is preferable that each layer is formed to a thickness of 0 nm to 300 nm. If the thicknesses of the high refractive index layer 13 and the low refractive index layer 14 are out of the above ranges, sufficient reflectance cannot be obtained.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G02B 5/26 G02B 5/26 (72) Inventor Kunio Sugamura 1-297 Kitabukurocho, Omiya-shi, Saitama Mitsubishi Materials Corporation Corporate Research Institute (72) Inventor Hitomi Taniguchi 1-1, Mikagecho, Tokuyama City, Yamaguchi Prefecture Tokuyama Corporation

Claims (4)

[Claims] 1. A glass layer (12) is formed on a substrate (11),
High refractive index layer (13) and low refractive index layer (14) on the glass layer (12)
A high-energy ray reflecting mirror having a laminate (15) in which and are alternately laminated a plurality of times. 2. The substrate (11) is Al ₂ O ₃ , AlN or SiC.
The high-energy ray reflecting mirror according to claim 1, which is made of the above ceramics. 3. A high-energy ray reflecting mirror according to claim 1, wherein the substrate (11) is made of W, Mo, Fe or Cu or an alloy thereof. 4. The glass layer (12) is formed to a thickness of 0.5 μm to 20 μm, and the high refractive index layer (13) is 30 nm to 150 n.
and a low refractive index layer (14) having a thickness of 60 nm to 30 nm.
The reflector for high-energy rays according to any one of claims 1 to 3, which is formed to have a thickness of 0 nm.