JP2815949B2 - Anti-reflective coating - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an antireflection film coated on optical glass.

[Prior art] Conventionally, in order to improve the reflection characteristics of the optical glass surface,
It is well known that an antireflection film is provided on this optical glass substrate. As such an anti-reflection film, for example, in US Pat. No. 3,185,020, a first layer having a thickness of λ / 4, a second layer having λ / 2, and a third layer being formed on a glass substrate. A three-layer antireflection film comprising λ / 4 (λ is a reference wavelength in an antireflection wavelength region) is disclosed. However, when the antireflection film disclosed in the aforementioned U.S. Patent Publication is applied to a glass lens, the antireflection effect over the entire visible wavelength range (380 to 780 nm) is insufficient. There is a problem that a flicker of reflection such as a phenomenon is felt. In order to solve the above problems, for example, Japanese Patent Publication No. 57-25801 discloses a seven-layer antireflection film, and Japanese Patent Publication No. 64-8801 discloses a multilayer antireflection film having four or more layers. ing.

[Problems to be Solved by the Invention] However, Japanese Patent Publication No. 57-25801 and Japanese Patent Publication No. 64-8
The antireflection film disclosed in Japanese Patent Publication No. 801 is provided with an inhomogeneous film having a property that the refractive index varies in the thickness direction of the film, such as TiO ₂ . Since the refractive index of the heterogeneous film largely depends on the degree of vacuum, it has a problem that it is difficult to obtain desired reflection characteristics with good reproducibility.

Therefore, an object of the present invention is to provide an excellent antireflection effect in the wavelength range of the visible light range, and it is difficult to cause a coast phenomenon and a flare phenomenon even when applied to a glass lens, and it is possible to obtain a desired reflection characteristic with good reproducibility. An object of the present invention is to provide an antireflection film.

[Means for Solving the Problems] As a result of intensive studies to achieve the above-mentioned object, the present invention provides a seven-layer antireflection film provided on a glass substrate having a refractive index of approximately 1.5 to 1.8. When the first layer and the second layer are counted in order from the base material, the following conditions are satisfied, and the sixth layer is made of a mixture containing ZrO ₂ and TiO _2. The present invention has been found.

First layer 1.38 ≦ n ₁ ≦ 1.39 0.07λ ₀ ≦ n ₁ d ₁ ≦ 0.14λ ₀ Second layer 1.62 ≦ n ₂ ≦ 2.05 0.02λ ₀ ≦ n ₂ d ₂ ≦ 0.07λ ₀ Third layer n ₃ ≧ 1.90 0.06 λ ₀ ≦ n ₃ d ₃ ≦ 0.10λ ₀ 4th layer 1.38 ≦ n ₄ ≦ 1.39 0.10λ ₀ ≦ n ₄ d ₄ ≦ 0.13λ ₀ 5th layer n ₅ ≧ 1.90 0.05λ ₀ ≦ n ₅ d ₅ ≦ 0.10λ ₀ 6th layer 2.05 ≦ n ₆ ≦ 2.15 0.48λ ₀ ≦ n ₆ d ₆ ≦ 0.52λ ₀ 7th layer 1.38 ≦ ₇ ≦ 1.39 0.23λ ₀ ≦ n ₇ d ₇ ≦ 0.27λ ₀ where λ ₀ is 450 to 550 nm , Ni represents a refractive index, nidi represents an optical film thickness, and i represents an integer of 1 to 7.

 Hereinafter, the present invention will be described in detail.

It is an essential condition that the sixth layer of the antireflection film of the present invention is composed of a mixed vapor-deposited film containing ZrO ₂ and TiO ₂ .
The reason is that by mixing ZrO ₂ with TiO ₂ , it is possible to adjust the heterogeneity of the heterogeneous film having the property that the refractive index differs in the thickness direction of the film thickness, and it does not show absorption. This is because the refractive index is as high as 2.05 to 2.15. The molar composition ratio of ZrO ₂ and TiO ₂ are, ZrO ₂ is relative to 1, TiO ₂ is 0.15 to 0.20 is preferably used.

The film material of each layer of the antireflection film of the present invention is not particularly limited as long as it satisfies the range of the refractive index and the optical thickness of each layer. Refractive index substance,
For example, MgF ₂ having a refractive index of 1.38 to 1.39, and the second layer made of Al ₂ O ₃
Or ZrO ₂ , the third and fifth layers are made of ZrO ₂ or ZrO ₂ and TiO ₂
And a mixture of the above. This is because a desired refractive index and a strong film strength can be obtained without exhibiting absorption.

Incidentally, the refractive index of the glass substrate in the present invention, from 1.5
Use the one in the range of 1.8. The reason is that if the refractive index of the glass substrate is in the range of 1.5 to 1.8, the deposition material of each layer of the antireflection film of the present invention can be applied to the glass substrate without changing the lamination order of the deposition material. Because it is possible.

In the present invention, the first to seventh layers can be provided by vacuum evaporation and sputtering. More preferably, it is vacuum evaporation. A method such as ion beam assist may be appropriately applied.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

FIG. 1 is a sectional view showing an antireflection film according to the present invention. In FIG. 1, the antireflection film C comprises a first layer 1, a second layer 2, a third layer 3, a fourth layer 5, a fifth layer 5, a sixth layer 6, It has a seventh layer 7 configuration.

Next, Table 1 shows specific configurations of Examples 1 to 4 of the present invention, Table 2 shows specific configurations of Examples 5 to 8, and Table 3 shows specific configurations of Examples 9 to 12. The spectral reflectance curves of Examples 1 to 3 are shown in FIG. 2, and the spectral reflectance curves of Examples 5 to 7 are shown in FIG.
FIG. 4 shows the spectral reflectance curves of Examples 9 to 11, and FIG. 5 shows the spectral reflectance curves of Examples 4, 8, and 12. However, Table 1
Optical film thickness of each layer in-Table 3 500n the design wavelength lambda ₀
This is the value when calculated as m.

In addition, the vapor deposition method used a vacuum vapor deposition method under the conditions of a substrate temperature of 300 ° C. and a degree of vacuum of 3 × 10 ⁻⁵ Torr. LHI-II (manufactured by Hoya Corporation) as a glass lens with a refractive index of 1.6, refractive index of 1.7
LHI (Hoya Co., Ltd.) as a glass lens
With THI-II (Jolla Co.) as a 1.8 glass lens, the molar composition ratio of ZrO ₂ and TiO ₂ is ZrO ₂ are relative to 1,
Performed with TiO ₂ at 0.18. As is clear from FIGS. 2 to 5, in any of the embodiments, the luminous reflectance of one side is:
It had an extremely excellent antireflection property of about 0.15% or less.

FIG. 6 shows the reflection with respect to the deposition time (change in film thickness) of the sixth layer when control is performed by monochromatic photometry (λ ₀ = 550 nm) and the sixth layer 0.50λ ₀ is formed five times repeatedly. It is a figure showing a rate change. As shown in FIG. 6, it is substantially the same reflectance value is Izure minimum extreme point b of the deposition starting point a and 0.50Ramuda ₀ in the case of, ZrO ₂ and consists of TiO ₂ film of the sixth layer It was homogeneous.

Furthermore, when the glass lenses provided with the anti-reflection film shown in Examples 1 to 12 were repeatedly manufactured, it was found that the single-sided luminous reflectance of all the glass lenses was about 0.15% or less, and the reflection characteristics were reproducibly obtained. did it.

[Effects of the Invention] As described in detail above, the antireflection film of the present invention, when provided on a glass lens, has a very low surface reflectance in the visible light wavelength range, and has an excellent antireflection effect. As a result, the ghost phenomenon and the flare phenomenon are eliminated and the lens can be used particularly suitably as a spectacle lens. In addition, since the sixth layer is made of a substance that can solve the problem of inhomogeneity, the reflection characteristics can be obtained with good reproducibility. Further, the antireflection film of the present invention can obtain substantially the same reflection characteristics in a glass lens having a refractive index of 1.5 to 1.8 without changing the deposition material and the stacking order of the deposition material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the structure of an antireflection film according to the present invention, FIG. 2 is a spectral reflectance curve diagram of Examples 1 to 3, and FIG.
FIG. 4 shows the spectral reflectance curves of Examples 5 to 7, and FIG.
FIG. 5 shows spectral reflectance curves of Examples 9 to 11, and FIG.
4, 8, and 12 are spectral reflectance curve diagrams, and FIG. 6 is a reflectance change diagram of the sixth layer in which the sixth layer is controlled by monochromatic photometry. A: glass substrate, B: air C: antireflection film 1: first layer, 2: second layer 3: third layer, 4: fourth layer 5: fifth layer, 6: sixth layer 7: first layer 7 layers

────────────────────────────────────────────────── (5) References JP-A-61-210175 (JP, A) JP-A-62-124503 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 1/10-1/12

Claims (4)

(57) [Claims] 1. A seven-layer antireflection film provided on a glass substrate having a refractive index of about 1.5 to 1.8, wherein the first layer and the second layer are counted in order from the substrate and the following conditions are satisfied. Wherein the sixth layer comprises a mixture containing ZrO ₂ and TiO ₂ ; the first layer 1.38 ≦ n ₁ ≦ 1.39 0.07λ ₀ ≦ n ₁ d ₁ ≦ 0.14λ ₀ Second layer 1.62 ≦ n ₂ ≦ 2.05 0.02λ ₀ ≦ n ₂ d ₂ ≦ 0.07λ ₀ Third layer n ₃ ≧ 1.90 0.06λ ₀ ≦ n ₃ d ₃ ≦ 0.10λ ₀ Fourth layer 1.38 ≦ n ₄ ≦ 1.39 0.10 _{λ 0 ≦ n 4 d 4 ≦} 0.13λ 0 fifth layer _{n 5 ≧ 1.90 0.05λ 0 ≦ n} 5 d 5 ≦ 0.10λ 0 sixth layer _{2.05 ≦ n 6 ≦ 2.15 0.48λ 0} ≦ n 6 d 6 ≦ 0.52λ ₀ 7th layer 1.38 ≦ n ₇ ≦ 1.39 0.23λ ₀ ≦ n ₇ d ₇ ≦ 0.27λ ₀ where λ ₀ is a design wavelength selected in the range of 450 to 550 nm, ni is a refractive index, and nidi is an optical film thickness , I represents an integer of 1 to 7. 2. The anti-reflection coating according to claim 1, wherein the first, fourth and seventh layers are made of MgF ₂ . 3. The antireflection film according to claim 1, wherein the second layer is made of Al ₂ O ₃ or ZrO ₂ . 4. The antireflection film according to claim 1, wherein the third and fifth layers are made of ZrO ₂ or a mixture of ZrO ₂ and TiO ₂ .