JPH1010303A - Infrared antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an infrared antireflection film excellent in durability even in a severe environment while ensuring antireflection function by using a medium refractive index material in the 1st layer of an infrared antireflection film from the substrate side and a high refractive index material in the 2nd layer and laminating a film of Al2 O3 as a medium refractive index material as the outer most layer. SOLUTION: An infrared antireflection film is formed on an infrared optical substrate. A medium refractive index material is used in a 1st layer of the film from the substrate side, a high refractive index material is used-in a 2nd layer, and a film of Al2 O3 as a medium refractive index material is used is the outermost layer, and these layers are laminated with each other. In such a case, material selected from a group consisting of Ge, Si, Zn and ZnSe is preferable, and A2 O2 SiO, Zn, ZnSe and the like are embodied as the medium refractive index material which is used in the 1st layer and Ge, Si and the like are embodies as the high refractive index material which is used in the 2nd layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared antireflection film used as an optical member in the infrared region.

2. Description of the Related Art Heretofore, attention has been paid to the use of infrared light in the range of 3 to 5 μm as an optical member used for optical equipment in the infrared region. Along with this, an infrared antireflection film effective for infrared light in this region has been proposed. For example, Ge
On the substrate, a ZnS film or a ZnSe film having an intermediate refractive index is formed on the first layer from the substrate side, a Ge film having a high refractive index is formed on the second layer, and Zn is formed on the third layer.
S film, and an infrared antireflection film formed by forming a low refractive index BaF ₂ film or MgF ₂ film on the outermost layer (Japanese Patent Publication No.
No. 133761) and the like. However, such a conventional infrared anti-reflection film has Ba as an outermost layer.
Since a material with a low filling factor such as F ₂ or MgF ₂ is laminated, the durability is low, and the infrared antireflection function cannot be sufficiently performed in a severe environment, particularly under a high humidity condition.

[0002]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an infrared antireflection film having a sufficient antireflection function and excellent durability even in a severe environment.

SUMMARY OF THE INVENTION An object of the present invention is to provide an infrared antireflection film formed on a substrate for infrared optics, wherein the first layer from the substrate side has an intermediate refractive index material and the second layer has a high refractive index material. This is achieved by an infrared antireflection film characterized by laminating a refractive index material and an Al ₂ O ₃ film of an intermediate refractive index material on the outermost layer.

[0003]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a substrate,
Those selected from the group consisting of Ge, Si, ZnS and ZnSe are preferred. In the infrared antireflection film of the present invention, examples of the intermediate refractive index substance used as the first layer from the substrate side include Al ₂ O ₃ , SiO, Zn, ZnSe, and the like. In addition, Ge, Ge,
Si etc. are mentioned. The present invention is characterized in that Al ₂ O ₃ is laminated as an intermediate refractive index material of the outermost layer. In the present invention, it is preferable to stack an Al ₂ O ₃ film or SiO film of an intermediate refractive index material on the first layer and a Ge film on the second layer from the substrate side.

More preferably, the infrared antireflection film of the present invention is formed on a Ge substrate, from the substrate side, as a first layer, an Al ₂ O ₃ film or SiO film of an intermediate refractive index material, and as a second layer, a Ge film. And an Al ₂ O ₃ film laminated on the outermost layer. In this infrared antireflection film, the optical thicknesses d ₁ , d ₂ , and d ₃ of each of the first to third layers are determined by changing the refractive index of each layer to n ₁ , n ₂ , and n.
_{3. When} the design reference wavelength is λ ₀ , 0.12λ ₀ ≦ 4n ₁ d ₁ ≦ 0.26λ ₀ 0.29λ ₀ ≦ 4n ₂ d ₂ ≦ 0.42λ ₀ 0.90λ ₀ ≦ 4n ₃ d ₃ ≦ More preferably, it is 1.10λ ₀ . More preferably, the infrared anti-reflection film of the present invention is provided on a Si substrate, as a first layer from the substrate side, an Al ₂ O ₃ film or an SiO film of an intermediate refractive index substance,
A Ge film is laminated as a layer, and an Al ₂ O ₃ film is laminated as an outermost layer. In this infrared antireflection film, the optical thicknesses d ₁ , d ₂ , and d ₃ of each of the _first to _third layers correspond to the refractive indices n ₁ , n ₂ , and n ₃ , and the design reference wavelength. when the lambda _0, is _{0.10λ 0 ≦ 4n 1 d 1 ≦} 0.40λ 0 0.20λ 0 ≦ 4n 2 d 2 ≦ 0.37λ 0 0.90λ 0 ≦ 4n 3 d 3 ≦ 1.10λ 0 Is more preferable.

[0005] More preferably, the infrared antireflection of the present invention.
The film has a medium refractive index on the ZnS substrate and the first layer from the substrate side.
Material Al_TwoO_ThreeFilm or SiO film, Ge film as the second layer,
Al on the outermost layer_TwoO_ThreeIt is a stack of films. This infrared
In the anti-reflection film, the optical properties of each of the first to third layers
Film thickness d₁, D_Two, D_ThreeGives the refractive index of each layer as n₁, N_Two,
n_Three, Design reference wavelength λ₀0.31λ₀≤4n₁d₁≤0.75λ₀ 0.06λ₀≤4n_Twod_Two≤0.13λ₀ 0.70λ₀≤4n_Threed_Three≤1.20λ₀ Is more preferable. More preferably,
The bright infrared antireflection film is formed on the ZnSe substrate from the substrate side.
The first layer has an intermediate refractive index material of Al_TwoO_ThreeFilm or SiO film,
Ge film as the second layer, Al as the outermost layer_TwoO_ThreeLayered film
It is. In this infrared antireflection film, the first to the second layers
Optical thickness d of each of the three layers₁, D_Two, D_ThreeHowever, the bending of each layer
Folding rate n₁, N _Two, N_Three, Design reference wavelength λ₀Then
0.30λ₀≤4n₁d₁≤0.80λ₀ 0.04λ₀≤4n_Twod_Two≦ 0.11λ₀ 0.66λ₀≤4n_Threed_Three≤1.10λ₀ Is more preferable.

In the infrared anti-reflection film of the present invention, Y ₂ O ₃ , Al ₂ O ₃ , Ti ₂ O ₃ , Ti
O, TiO ₂ etc. adhesion strengthening layer, optical thickness 300 nm
By providing the layer with the following thickness, the adhesion can be improved without deteriorating the optical characteristics for reducing the reflection of infrared light. Further, by depositing a high refractive index material such as Ge between the substrate and the first intermediate refractive index material layer or the adhesion layer, the adhesion to the substrate is improved and the reflection is suppressed. , The amount of transmitted light can be increased.
Hereinafter, the present invention will be described more specifically with reference to Examples.

Example of infrared antireflection film formed on Ge substrate Example 1 Substrate Ge First layer Al ₂ O ₃ Optical thickness 0.18λ ₀ Second layer Ge 〃 0.34λ ₀ Outer layer Al ₂ O ₃ 〃 1.00Ramuda ₀ the wavelength lambda ₀ as a reference is 4.2 .mu.m. FIG. 1 shows the optical characteristics of the infrared antireflection film. Further, Si may be stacked instead of Ge as the second layer.

Example 2 In Example 1, S 1 was used instead of Al ₂ O _{3 in} the first layer.
It is a laminate of iO. Board Ge first layer SiO optical thickness 0.21Ramuda ₀ second layer Ge 〃 0.34Ramuda ₀ outermost Al ₂ O ₃ 〃 1.00Ramuda ₀ The wavelength lambda ₀ as a reference is 4.15Myuemu. FIG. 2 shows the optical characteristics of the infrared antireflection film. Further, Si may be stacked instead of Ge as the second layer.

Example 3 Substrate Ge First layer Adhesion strengthening layer (Y ₂ O ₃ ) Optical film thickness 270 nm Second layer Al ₂ O ₃ 〃0.13λ ₀ Third layer Ge 〃0.34 λ ₀ Outermost layer al ₂ O ₃ 〃 1.00Ramuda ₀ the wavelength lambda ₀ as a reference is 4.2 .mu.m. FIG. 3 shows the optical characteristics of the infrared antireflection film. In addition, Si may be laminated instead of Ge of the third layer.

Example 4 In Example 3, S ₂ was used instead of Al ₂ O _{3 in} the second layer.
It is a laminate of iO. Board Ge first layer adhesion-reinforcing layer (Y ₂ O ₃₎ an optical film thickness of 270nm second layer SiO 〃 0.16Ramuda ₀ third layer Ge 〃 0.32Ramuda ₀ outermost Al ₂ O ₃ 〃 1.00Ramuda ₀ The reference wavelength λ ₀ is 4.15 μm. FIG. 4 shows the optical characteristics of the infrared antireflection film. In addition, Si may be laminated instead of Ge of the third layer.

Example 5 Substrate Ge First layer Ge Optical thickness 0.17λ ₀ Second layer Al ₂ O ₃ 〃 0.19λ ₀ Third layer Ge 〃 0.34λ ₀ Outermost layer Al ₂ O ₃ 〃1 .00λ _{0 The} reference wavelength λ ₀ is 4.15 μm. FIG. 5 shows the optical characteristics of the infrared antireflection film. In addition, Si may be laminated instead of Ge of the third layer.

Example 6 In Example 5, S ₂ was replaced with Al ₂ O _{3 in} the second layer.
It is a laminate of iO. Base Ge First layer Ge Optical thickness 0.34λ ₀ Second layer SiO 層 0.23λ ₀ Third layer Ge〃0.34λ ₀ Outermost layer Al ₂ O ₃ 〃1.000λ ₀ Reference wavelength λ ₀ is 4.15 μm. FIG. 6 shows the optical characteristics of the infrared antireflection film. In addition, Si may be laminated instead of Ge of the third layer.

Example 7 Substrate Ge First layer Adhesion strengthening layer (Y ₂ O ₃ ) Optical thickness 270 nm Second layer Ge〃0.17λ ₀ Third layer Al ₂ O ₃ 〃0.16λ ₀ Fourth Layer Ge〃0.29λ ₀ Outermost layer Al ₂ O ₃ 〃1.000λ _{0 The} reference wavelength λ ₀ is 4.10 μm. FIG. 7 shows the optical characteristics of this infrared antireflection film. Ge of the fourth layer
Alternatively, Si may be laminated.

Example 8 In Example 7, S ₃ was used instead of Al ₂ O _{3 in} the third layer.
It is a laminate of iO. Board Ge first layer adhesion-reinforcing layer (Y ₂ O ₃₎ an optical film thickness of 270nm second layer Ge 〃 0.24Ramuda ₀ third layer SiO 〃 0.21Ramuda ₀ fourth layer Ge 〃 0.27Ramuda ₀ outermost al ₂ O ₃ 〃 1.00Ramuda ₀ the wavelength lambda ₀ as a reference is 4.10Myuemu. FIG. 8 shows the optical characteristics of this infrared antireflection film. Ge of the fourth layer
Alternatively, Si may be laminated.

Example of infrared antireflection film formed on Si substrate Example 9 Substrate Si First layer Al ₂ O ₃ Optical thickness 0.20λ ₀ Second layer Ge 0.27λ ₀ Outermost layer Al ₂ O ₃ 〃 1.00Ramuda ₀ the wavelength lambda ₀ as a reference is 4.3 [mu] m. FIG. 9 shows the optical characteristics of the infrared antireflection film. Si may be laminated instead of Ge of the second layer.

Example 10 Substrate Si First layer SiO Optical thickness 0.23λ ₀ Second layer Ge〃0.41λ ₀ Outermost layer Al ₂ O ₃ 〃1.000λ _{0 The} reference wavelength λ ₀ is 4.3 μm. FIG. 10 shows the optical characteristics of this infrared antireflection film. Ge of the second layer
Alternatively, Si may be laminated.

EXAMPLE 11 Substrate Si First Layer Adhesion Strengthening Layer (Y ₂ O ₃ ) Optical Film Thickness 270 nm Second Layer Al ₂ O ₃ 〃0.15λ ₀ Third Layer Ge 〃0.27λ ₀ Outer Layer Al ₂ O ₃ 〃 1.00λ _{0 The} reference wavelength λ ₀ is 4.3 μm. FIG. 11 shows the optical characteristics of the infrared antireflection film. Ge of the third layer
Alternatively, Si may be laminated.

Embodiment 12 In Embodiment 11, SiO is laminated instead of the second layer of Al ₂ O ₃ . Substrate Si First layer Adhesion reinforcing layer (Y ₂ O ₃ ) Optical thickness 270 nm Second layer SiO〃0.18λ ₀ Third layer Ge〃0.25λ ₀ Outermost layer Al ₂ O ₃ 〃1.000λ ₀ The reference wavelength λ ₀ is 4.3 μm. FIG. 12 shows the optical characteristics of the infrared antireflection film. Ge of the third layer
Alternatively, Si may be laminated.

Example 13 Substrate Si First layer Ge Optical thickness 0.32λ ₀ Second layer Al ₂ O ₃ 〃 0.24λ ₀ Third layer Ge 〃 0.33λ ₀ Outermost layer Al ₂ O ₃ 〃1 .00λ _{0 The} reference wavelength λ ₀ is 4.3 μm. FIG. 13 shows the optical characteristics of this infrared antireflection film. Ge of the third layer
Alternatively, Si may be laminated.

Embodiment 14 In Embodiment 13, SiO is laminated instead of the second layer of Al ₂ O ₃ . Substrate Si First layer Ge Optical thickness 0.39λ ₀ Second layer SiO 〃 0.27λ ₀ Third layer Ge 〃 0.34 λ ₀ Outermost layer Al ₂ O ₃ ００ 1.00 λ ₀ Reference wavelength λ ₀ is 4.3 μm. FIG. 14 shows the optical characteristics of the infrared antireflection film. Ge of the third layer
Alternatively, Si may be laminated.

Example 15 Substrate Si First layer Adhesion strengthening layer (Y ₂ O ₃ ) Optical film thickness 270 nm Second layer Ge〃0.34λ ₀ Third layer Al ₂ O ₃ .0.25λ ₀ Fourth Layer Ge〃0.29λ ₀ Outermost layer Al ₂ O ₃ 〃1.000λ _{0 The} reference wavelength λ ₀ is 4.3 μm. FIG. 15 shows the optical characteristics of this infrared antireflection film. Ge of the fourth layer
Alternatively, Si may be laminated.

Embodiment 16 In Embodiment 15, SiO is laminated instead of the third layer of Al ₂ O ₃ . Substrate Si First layer Adhesion reinforcing layer (Y ₂ O ₃ ) Optical film thickness 270 nm Second layer Ge〃0.39λ ₀ Third layer SiO〃0.31λ ₀ Fourth layer Ge〃0.28λ ₀ Outermost layer Al ₂ O ₃ 〃 1.00λ _{0 The} reference wavelength λ ₀ is 4.35 μm. FIG. 16 shows the optical characteristics of this infrared antireflection film. 4th layer G
Si may be laminated instead of e.

Example 17 Substrate ZnS First layer Al ₂ O ₃ Optical thickness 0.46 λ ₀ Second layer GeＧ0.09 λ ₀ Outermost layer Al ₂ O ₃ 〃 1.00 λ ₀ Reference wavelength λ ₀ is 6.3 μm. FIG. 17 shows the optical characteristics of the infrared antireflection film. Example 18 In Example 17, an adhesion reinforcing layer (Y ₂ O ₃ ) was laminated between the substrate and the first layer. Substrate ZnS First layer Adhesion strengthening layer (Y ₂ O ₃ ) Optical thickness 270 nm Second layer Al ₂ O ₃ 〃 0.46 λ ₀ Third layer Ge 〃 0.09 λ ₀ Outermost layer Al ₂ O ₃ 〃 1 .00λ _{0 The} reference wavelength λ ₀ is 6.3 μm. FIG. 18 shows the optical characteristics of the infrared antireflection film.

Example 19 In Example 17, SiO was laminated instead of the first layer of Al ₂ O ₃ . Substrate ZnS First layer SiO Optical thickness 0.61λ ₀ Second layer Ge〃0.09λ ₀ Outermost layer Al ₂ O ₃ 〃1.000λ _{0 The} reference wavelength λ ₀ is 5.4 μm. FIG. 19 shows the optical characteristics of the infrared antireflection film. Example 20 In Example 19, an adhesion reinforcing layer (Y ₂ O ₃ ) was laminated between the substrate and the first layer. Board ZnS first layer adhesion-reinforcing layer (Y ₂ O ₃₎ an optical film thickness of 270nm second layer SiO 〃 0.61 ₀ third layer Ge 〃 0.09Ramuda ₀ outermost Al ₂ O ₃ 〃 1.00Ramuda ₀ The reference wavelength λ ₀ is 5.4 μm. FIG. 20 shows the optical characteristics of this infrared antireflection film.

Example 21 Substrate ZnSe First layer Al ₂ O ₃ Optical film thickness 0.46λ ₀ Second layer Ge〃0.07λ ₀ Outermost layer Al ₂ O ₃ 〃1.000 ₀ Reference wavelength λ ₀ is 6.3 μm. FIG. 21 shows the optical characteristics of this infrared antireflection film. Example 22 In Example 21, an adhesion reinforcing layer (Y ₂ O ₃ ) was laminated between the substrate and the first layer. Substrate ZnSe First layer Adhesion strengthening layer (Y ₂ O ₃ ) Optical thickness 270 nm Second layer Al ₂ O ₃ 〃 0.46 λ ₀ Third layer Ge 〃 0.07 λ ₀ Outermost layer Al ₂ O ₃ 〃 1 .00λ _{0 The} reference wavelength λ ₀ is 6.3 μm. FIG. 22 shows the optical characteristics of the infrared antireflection film.

Embodiment 23 In Embodiment 21, SiO is laminated instead of the first layer of Al ₂ O ₃ . Substrate ZnSe First layer SiO Optical thickness 0.56λ ₀ Second layer Ge 0.09λ ₀ Outermost layer Al ₂ O ₃ 〃1.000λ _{0 The} reference wavelength λ ₀ is 5.8 μm. FIG. 23 shows the optical characteristics of this infrared antireflection film. Example 24 In Example 23, an adhesion reinforcing layer (Y ₂ O ₃ ) was laminated between the substrate and the first layer. Board ZnSe first layer adhesion-reinforcing layer (Y ₂ O ₃₎ an optical film thickness of 270nm second layer SiO 〃 0.56Ramuda ₀ third layer Ge 〃 0.09Ramuda ₀ outermost Al ₂ O ₃ 〃 1.00Ramuda ₀ The reference wavelength λ ₀ is 5.8 μm. FIG. 24 shows the optical characteristics of the infrared antireflection film.

Comparative Example 1 This comparative example is a conventional infrared antireflection film described in Japanese Patent Publication No. 2-11121. Substrate Ge First layer ZnS Optical thickness 0.4 μm Second layer Ge〃0.8 μm Third layer ZnS〃1.7 μm Fourth layer BaF ₂ 〃1.0 μm Outermost layer ZnS〃0.3 μm

Comparative Example 2 This comparative example is a conventional infrared anti-reflection coating described in Japanese Patent Publication No. 2-13761. Substrate Ge First layer ZnS Optical thickness 0.45 μm Second layer Ge 0.90 μm Third layer ZnS〃2.45 μm Outermost layer BaF ₂ 〃2.00 μm

Comparative Example 3 This comparative example is described as Comparative Example 1 of Japanese Patent Application No. 6-249127, in which the first layer is disposed between the substrate and the second layer.
A layer in which an adhesion reinforcing layer (Ti ₂ O ₃ ) is laminated as a layer. Board Ge first layer Ti ₂ O ₃ optical film thickness 200nm second layer ZnS 〃 0.21Ramuda ₀ third layer Ge 〃 0.33? ₀ fourth layer ZnS 〃 1.00Ramuda ₀ outermost MgF ₂ 〃 1.00Ramuda _{0 The} reference wavelength λ ₀ is 3.2 μm.

Comparative Example 4 This comparative example is described as Comparative Example 2 of Japanese Patent Application No. 6-249127. Substrate Si First layer Ti ₂ O ₃ Optical thickness 200 nm Second layer ZnS〃0.24λ ₀ Third layer Ge〃0.31λ ₀ Fourth layer ZnS〃1.17λ ₀ Outermost layer MgF ₂ 〃1.000λ _The reference wavelength λ ₀ is 3.7 μm.

Comparative Example 5 This comparative example is described as Comparative Example 3 of Japanese Patent Application No. 6-249127. Substrate ZnS First layer Ti ₂ O ₃ Optical thickness 200 nm Second layer ZnSＳ0.20λ ₀ Third layer Ge〃0.10λ ₀ Fourth layer ZnS〃1.39λ ₀ Outermost layer MgF ₂ 〃1.000λ _The reference wavelength λ ₀ is 3.9 μm.

Comparative Example 6 This comparative example is described as Comparative Example 4 in Japanese Patent Application No. 6-249127. Board ZnSe first layer Ti ₂ O ₃ optical film thickness 200nm second layer ZnS 〃 0.21Ramuda ₀ third layer Ge 〃 0.15Ramuda ₀ fourth layer ZnS 〃 1.30Ramuda ₀ outermost MgF ₂ 〃 1.00λ _The reference wavelength λ ₀ is 3.9 μm.

Test Examples The infrared antireflection films of Examples 1 to 16 and Comparative Examples 1 to 6 were subjected to an adhesion test, an abrasion resistance test, a moisture resistance test 1 and a moisture resistance test 2 by the following methods. The durability under severe environment was examined. Adhesion test (MIL-C-13508C 4.4.6) Adhere cellophane tape and visually observe whether the film peels off when it is peeled off. Abrasion resistance test (MIL-C-13508C 4.4.5) A 50-stroke test is performed by applying a pressure of 500 g using cheesecloth, and it is visually observed whether or not the film surface is damaged. Moisture resistance test 1 (MIL-C-13508C 4.4.7) Each of the infrared antireflection films to be compared, for example, those of Example 1 and Comparative example 1 are left in an atmosphere at a temperature of 50 ° C. and a humidity of 95% for 24 hours. . Moisture resistance test 2 (MIL-STD-810D 507.2-3) A cycle consisting of 6 hours under environmental conditions of 30 ° C. and 95% humidity, and then 6 hours under environmental conditions of 60 ° C. and 95% humidity is defined as one cycle. This cycle is repeated, and is continued for 10 days, and it is visually observed whether or not the film is damaged. In addition, each of the infrared antireflection films to be compared was
→ Tested in order. The results are shown in Table 1 below.

[0034]

[Table 1] Test Test Test Test Comparative Example 1 ○ ○ ○ × 〃 2 ○ ×--〃 3 ○ ○ ○ × 〃 4 ○ ○ ○ × ５ 5 ○ ○ ○ × ６ 6 ○ ○ ○ × Example 1 ○ ○ ○ ○ 〃 2 ○ ○ ○ ○ ○ 〃 3 ○ ○ ○ ○ 〃 4 ○ ○ ○ ○ 〃 5 ○ ○ ○ ○ 〃 6 ○ ○ ○ ○ 〃 7 ○ ○ ○ ○ 〃 8 ○ ○ ○ ○ 〃 9 ○ ○ ○ ○ 〃 10 ○ ○ ○ ○ 〃 11 ○ ○ ○ ○ 〃 12 ○ ○ ○ ○ 〃 13 ○ ○ ○ ○ 〃 14 ○ ○ ○ ○ 〃 15 ○ ○ ○ ○ 〃 16 ○ ○ ○ ○ 〃 17 ○ ○ ○ ○ 〃 18 ○ ○ ○ ○ 〃 19 ○ ○ ○ ○ 〃 20 ○ ○ ○ ○ 〃 21 ○ ○ ○ ○ 〃 22 ○ ○ ○ ○ 〃 23 ○ ○ ○ ○ 〃 24 ○ ○ ○ ○ 〃 24 ○ ○ ○ ○ ○ X indicates that there was an abnormality such as peeling or damage, and-indicates that the test could not be continued.

From the above test results, the infrared anti-reflection film of the present invention was obtained by laminating an intermediate refractive index material Al ₂ O ₃ film on the outermost layer, and thereby forming a low refractive index material BaF _{2 on the} conventional outermost layer.
Or, it is understood that the durability is higher than that of the infrared anti-reflection film in which MgF ₂ is laminated, and the infrared anti-reflection function can be sufficiently exerted even in a severe environment.

[Brief description of the drawings]

FIG. 1 is a diagram showing spectral characteristics of an infrared antireflection film of Example 1.

FIG. 2 is a diagram illustrating spectral characteristics of an infrared antireflection film of Example 2.

FIG. 3 is a diagram illustrating spectral characteristics of an infrared antireflection film of Example 3.

FIG. 4 is a diagram illustrating spectral characteristics of an infrared antireflection film of Example 4.

FIG. 5 is a diagram showing the spectral characteristics of an infrared antireflection film of Example 5.

FIG. 6 is a diagram illustrating spectral characteristics of an infrared antireflection film of Example 6.

FIG. 7 is a diagram showing the spectral characteristics of an infrared antireflection film of Example 7.

FIG. 8 is a diagram showing spectral characteristics of an infrared antireflection film of Example 8.

FIG. 9 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 9.

FIG. 10 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 10.

FIG. 11 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 11.

FIG. 12 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 12.

FIG. 13 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 13.

FIG. 14 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 14.

FIG. 15 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 15.

FIG. 16 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 16.

FIG. 17 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 17.

FIG. 18 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 18.

FIG. 19 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 19.

FIG. 20 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 20.

FIG. 21 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 21.

FIG. 22 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 22.

FIG. 23 is a diagram showing the spectral characteristics of the infrared anti-reflection film of Example 23.

FIG. 24 is a diagram showing the spectral characteristics of the infrared antireflection film of Example 24.

Claims (11)

[Claims] 1. An infrared anti-reflection film formed on an infrared optical substrate, wherein an intermediate refractive index substance is provided on a first layer from the substrate side.
The second layer has a high refractive index substance, and the outermost layer has an intermediate refractive index substance A.
An infrared anti-reflection film characterized by laminating l ₂ O ₃ films. 2. The infrared ray according to claim 1, wherein an Al ₂ O ₃ film or SiO film of an intermediate refractive index material is laminated on the first layer from the substrate side, and a Ge film is laminated on the second layer. Anti-reflection film. 3. The substrate is made of Ge, Si, ZnS and ZnS.
3. The infrared antireflection film according to claim 1, wherein the infrared antireflection film is selected from the group consisting of e. 4. An infrared anti-reflection film formed on a Ge substrate, wherein the first layer from the substrate side has an intermediate refractive index material of Al _2.
O ₃ film or SiO film, Ge film as the second layer, Al as the outermost layer
An infrared anti-reflection film characterized by laminating a ₂ O ₃ film. 5. The optical thickness d of each of the first to third layers
₁ , d ₂ and d ₃ denote the refractive indices of the respective layers as n ₁ , n ₂ , n ₃ ,
Assuming that the design reference wavelength is λ ₀ , 0.12λ ₀ ≦ 4n ₁ d ₁ ≦ 0.26λ ₀ 0.29λ ₀ ≦ 4n ₂ d ₂ ≦ 0.42λ ₀ .90λ ₀ ≦ 4n ₃ d ₃ ≦ 1. infrared reflection preventing film according to claim 4 10 [lambda] _0. 6. An infrared anti-reflection film formed on a Si substrate, wherein the first layer from the substrate side has an intermediate refractive index material of Al _2.
O ₃ film or SiO film, Ge film as the second layer, Al as the outermost layer
An infrared anti-reflection film characterized by laminating a ₂ O ₃ film. 7. The optical thickness d of each of the first to third layers
₁ , d ₂ and d ₃ denote the refractive indices of the respective layers as n ₁ , n ₂ , n ₃ ,
When the design reference wavelength is λ ₀ , 0.10λ ₀ ≦ 4n ₁ d ₁ ≦ 0.40λ ₀ .20λ ₀ ≦ 4n ₂ d ₂ ≦ 0.37λ ₀ .90λ ₀ ≦ 4n ₃ d ₃ ≦ 1. infrared reflection preventing film according to claim 6 10 [lambda] _0. 8. An infrared anti-reflection film formed on a ZnS substrate, wherein the first layer from the substrate side has an intermediate refractive index material of Al.
₂ O ₃ film or SiO film, Ge film as the second layer, A as the outermost layer
An infrared anti-reflection film characterized by laminating l ₂ O ₃ films. 9. The optical thickness d of each of the first to third layers
₁ , d ₂ and d ₃ denote the refractive indices of the respective layers as n ₁ , n ₂ , n ₃ ,
When the design reference wavelength is λ ₀ , 0.31λ ₀ ≦ 4n ₁ d ₁ ≦ 0.75λ ₀ .06λ ₀ ≦ 4n ₂ d ₂ ≦ 0.13λ ₀ .70λ ₀ ≦ 4n ₃ d ₃ ≦ 1. infrared reflection preventing film according to claim 8 20Ramuda is _0. 10. An infrared anti-reflection film formed on a ZnSe substrate, an Al ₂ O ₃ film or SiO film of an intermediate refractive index material as a first layer from the substrate side, a Ge film as a second layer, and an outermost layer. An infrared anti-reflection film characterized by laminating an Al ₂ O ₃ film thereon. 11. The optical thicknesses d ₁ , d ₂ and d ₃ of each of the _first to _third layers are determined by setting the refractive index of each layer to n ₁ , n ₂ ,
When n ₃ is λ ₀ and the design reference wavelength is λ ₀ , 0.30λ ₀ ≦ 4n ₁ d ₁ ≦ 0.80λ ₀ 0.04λ ₀ ≦ 4n ₂ d ₂ ≦ 0.11λ ₀ 0.66λ ₀ ≦ 4n ₃ d ₃ infrared reflection preventing film according to ≦ 1.10Ramuda ₀ claim 10.