JP3067134B2 - Multilayer film for optical parts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multilayer film for optical parts, in particular, adhesion, solvent resistance,
The present invention relates to a multilayer film for optical components having excellent environmental resistance.

2. Description of the Related Art A multilayer film is formed on an optical component for the purpose of improving an antireflection effect or durability. Therefore, the multi-layer film is required to have excellent durability without being peeled or damaged by a little friction.

In particular, many resin optical components have been introduced today to reduce the weight of cameras, videos, and the like.However, when a multilayer film is formed on a resin substrate, the resin substrate is not used due to the low heat resistance of the resin. It cannot be heated. Even if a multilayer film is formed thereon without heating the substrate, the multilayer film is inferior in film strength such as adhesion and durability such as solvent resistance and environmental resistance. Therefore, it is very difficult to form a multilayer film having excellent durability such as film strength and solvent resistance on a resin substrate without heating, and the types of multilayer films that can be formed on a resin substrate are very few and limited. It was.

Further, even when a glass substrate is used as the substrate of the optical component, it is difficult to form a multilayer film having excellent film strength and durability on the substrate without heating.

As a technique for improving the adhesion of a multilayer film on a resin substrate, an aluminum layer having a thickness of 2 to 5 μm is formed on a resin substrate, and a MgF ₂ layer is formed thereon (Japanese Patent Publication No. 47-3818).
Japanese Patent Application Laid-Open No. 62-186202), or a technique in which a vapor deposition layer of metal Cr or the like is formed on a resin substrate and a MgF ₂ dielectric layer is formed thereon. However, the configuration is different from that of the present invention, and the effect achieved is also different.

Problems to be Solved by the Invention The present invention does not change over time in properties and the like even when formed on an optical component, especially a resin optical component, and has durability such as film strength such as adhesion, solvent resistance and environmental resistance. An object of the present invention is to provide a multilayer film having excellent properties.

A layer consisting of a layer and the thickness 500Å or more YF ₃ having a thickness of 100Å or less of metallic Cr to the means resin substrate to solve the issues related to multilayer optical part comprising in this order.

The metal Cr layer is preferably formed directly on the substrate, and a YF ₃ layer is formed on the metal Cr layer. Further multilayer (e.g. anti-reflection film, a half mirror or the like) having the desired properties to the YF ₃ layers on to form a. With such a configuration, the multilayer film including the metal Cr layer and the YF ₃ layer and the resin substrate have excellent adhesion and environmental resistance.

The synthetic resin substrate is not particularly limited as long as it is of a type usually used as an optical component. For example, polymethyl methacrylate resin, polycarbonate CR-39
And the like, and the present invention is particularly effective for a resin having low heat resistance.

According to the present invention, a metal Cr layer is provided on the synthetic resin substrate. The metal Cr layer has a function of increasing the adhesion between the substrate and the multilayer film formed on the Cr layer, and the obtained optical component has improved durability against high temperature and high humidity.

The metal Cr layer can be formed by electron gun evaporation or resistance heating evaporation, and in this case, is formed to a thickness not exceeding 100 mm. This is because if the thickness is more than 100 °, the light transmittance is extremely reduced.

The on the metal Cr layer to form a YF ₃ layers. The _three layers of YF serve to increase solvent resistance (particularly organic solvents). The YF ₃ layer can be formed by evaporating the YF ₃ material with an electron gun (abbreviated as EB) using a carbon crucible without heating the substrate. The thickness depends on the constituent materials of the multilayer film and the conditions of each coating, but may be about 500 to 1 μm. If the layer is formed too thick, cracks or peeling are likely to occur.

In the present invention, it may be further formed metal Cr layer on the YF ₃ layers on. This Cr layer is effective for preventing cracking of the YF ₃ layer, and at this time, the thickness of the Cr layer formed on the substrate is reduced.
The total thickness should not exceed the above-mentioned thickness, that is, 100 °.

Multilayer film for optical components is used for engineering component substrates (especially resin substrates)
By stacking through the metal Cr layer and YF ₃ layer formed on the upper, solvent resistance, durability of environmental resistance, etc., excellent multilayer film adhesion can be obtained. In particular, the effect is more remarkable for a resin substrate. According to the present invention, by interposing the YF ₃ layer and the metal Cr layer, it becomes possible to use a vapor deposition material that could not be used due to insufficient film strength.
It is possible to obtain a multilayer film having various excellent optical characteristics, for example, an antireflection film, a half mirror, and the like.

For example six layers (first layer from the air side, the second layer, third layer, fourth layer, fifth layer, the sixth layer) and an anti-reflection film made of a metal Cr layer and YF ₃ layer on the substrate In the case of a configuration in which accumulation is performed in that order, the refractive index (n), the film thickness (d), and the optical film thickness (n
d) is formed so as to satisfy the following range or relationship.

The first layer refractive index; n ₁ ≦ ns optical _{thickness; 0.2λ 0 ≦ n 1 d 1} ≦ 0.3λ 0 second layer refractive index; 1.8 ≦ n ₂ optical thickness; 0.35λ ≦ n ₂ d ₂ ≦ 0.6λ ₀ third layer refractive index; n ₃ ≦ n ₄ optical film thickness; 0.03λ ₀ ≦ n ₃ d ₃ ≦ 0.15λ ₀ fourth layer refractive index; ns ≦ n ₄ optical film thickness; 0.03λ ₀ ≦ n ₄ d ₄ ≦ 0.25λ ₀ Fifth layer The thickness of the YF ₃ layer is 500 mm or more and 1 μm or less. The sixth layer The thickness of the metal Cr layer is 100 mm or less. Here, ns is the refractive index of the substrate, and n ₁ is the first layer. The refractive index, n ₂ is the refractive index of the second layer, n ₃ is the refractive index of the third layer, n ₄ is the refractive index of the fourth layer, d ₁ is the film thickness of the first layer, and d ₂ is the refractive index of the second layer. Thickness, d ₃ is third
The thickness of the layer, d ₄ is the thickness of the fourth layer, and λ ₀ is the dominant wavelength.

In the above multilayer structure, if the first, second and fourth layers deviate from the above range, a sufficient antireflection effect cannot be obtained in a desired wavelength region. The same applies to the case where the third layer deviates from the above range. In particular, the lower limit of the film thickness is defined from the viewpoint of forming technology. When the thickness of the sixth metal Cr layer exceeds 100 °, not only the transmittance is reduced but also the antireflection effect is adversely affected.

5 layers (first layer, second layer, third layer, fourth layer,
For the antireflection film made of the fifth layer), a metal Cr layer, the other layers except YF ₃ layer has a refractive index from the viewpoint of antireflection effect (n), thickness (d) and optical film thickness (nd) is less It is formed so as to satisfy the described range or relationship. If the value deviates from the range or the relationship is not satisfied, a sufficient antireflection effect cannot be obtained.

The first layer refractive index; n ₁ ≦ ns optical _{thickness; 0.2λ 0 ≦ n 1 d 1} ≦ 0.3λ 0 second layer refractive index; 1.8 ≦ n ₂ optical thickness; 0.35λ ₀ ≦ n ₂ d ₂ ≦ 0.6λ ₀ Third layer Refractive index; 1.5 ≦ n ₃ ≦ 1.8 Optical film thickness; 0.15λ ₀ ≦ n ₃ d ₃ ≦ 0.35λ ₀ Fourth layer (YF ₃ layer) Thickness not less than 500 mm and not more than 1 μm Layer (metal Cr layer) 100 ° or less In addition, ns is the refractive index of the substrate, n ₁ is the refractive index of the first layer, n ₂ is the refractive index of the second layer, n ₃ is the refractive index of the third layer, and d ₁ is the refractive index of the third layer. The thickness of the first layer, d ₂ is the thickness of the second layer, d ₃ is the thickness of the third layer, and λ ₀ is the dominant wavelength.

In the above-described reflection film configuration, a six-layer antireflection film is formed by setting the fourth layer to a metal Cr layer, the fifth layer to a YF3 layer, and the sixth layer to a metal Cr layer while leaving the first to _third layers as they are. It may be formed. At this time, the film thickness is in the above-mentioned range.

7 layers (first layer, second layer, third layer, fourth layer,
In the case of an antireflection film composed of (fifth layer, sixth layer, and seventh layer),
Each layer other than the metal Cr layer and the YF ₃ layer is formed so that the refractive index (n), the film thickness (d), and the optical film thickness (nd) satisfy the following ranges or relationships from the viewpoint of the antireflection effect. You.
If you deviate from that range or do not satisfy those relationships,
A sufficient antireflection effect cannot be obtained. The lower limits of the thicknesses of the third layer and the fourth layer are defined from the viewpoint of forming technology, and it is impossible to form a film whose thickness is controlled to a lower value. That is, the first layer to the fourth layer have the following constitutions; the first layer refractive index; n ₁ ≦ ns optical film thickness; 0.2λ ₀ ≦ n ₁ d ₁ ≦ 0.3λ ₀ the second layer refractive index; 1.8 ≦ n ₂ Optical film thickness; 0.35λ ₀ ≦ n ₂ d ₂ ≦ 0.6λ ₀ Third layer Refractive index; n ₃ ≦ n ₄ Optical film thickness; 0.03λ ₀ ≦ n ₃ d ₃ ≦ 0.15λ ₀ Fourth layer refraction Ratio: ns ≦ n ₄ Optical film thickness: 0.03λ ₀ ≦ n ₄ d ₄ ≦ 0.25λ ₀ The fifth layer is a metal Cr layer, the sixth layer is a YF ₃ layer, and the seventh layer is a metal Cr layer.

Here, ns is the refractive index of the substrate, n ₁ is the refractive index of the first layer, n ₂ is the refractive index of the second layer, n ₃ is the refractive index of the third layer, n ₄ is the refractive index of the fourth layer, d ₁ the thickness of the first layer, d ₂ is the thickness of the second layer, d ₃ is the third
The thickness of the layer, d ₄ is the thickness of the fourth layer, and λ ₀ is the dominant wavelength.

The present invention is also effective for a half mirror. For example, the configuration of a half mirror composed of five layers is as follows.

First layer refractive index; n ₂ ≦ n ₁ optical thickness; 0.2λ ≦ n ₁ d ₁ ≦ 0.3λ ₀ Second layer refractive index; n ₂ ≦ n ₃ optical thickness; 0.2λ ₀ ≦ n ₂ d ₂ ≦ _{0.3λ 0} third layer refractive index; n ₃ ≧ ns optical _{thickness; 0.2λ 0 ≦ n 3 d 3} ≦ 0.3λ 0 fourth layer (YF ₃ layers) 500 Å or 1μm or less fifth layer (Cr layer 100 ° or less Note that ns is the refractive index of the substrate, n ₁ is the refractive index of the first layer, n ₂ is the refractive index of the second layer, n ₃ is the refractive index of the third layer, and d ₁ is the film of the first layer. The thickness, d ₂ is the thickness of the second layer, d ₃ is the thickness of the third layer, and λ ₀ is the dominant wavelength.

If the first to third layers deviate from the above ranges, sufficient reflectance and transmittance cannot be obtained.

The above film configuration is exemplary, and in the present invention, Cr,
Film structure other than YF ₃ is not limited to those shown herein, it may be any configuration necessary to obtain the desired spectral characteristics.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example An antireflection film or a half mirror shown in Tables 1 to 5 was produced on an optical component substrate.

The antireflection characteristics and spectral characteristics of the obtained optical components are shown in FIGS. 1 to 5 corresponding to the table numbers.

 Note that the antireflection film has an incident angle of 0 °.

 The half mirror (Example 3) has an incident angle of 45 °.

An endurance test was performed on Examples 1 to 5.

 The following three items were performed as a durability test.

1. Tape peeling test The operation of peeling the tape vertically after bonding the tape on the thin film surface is repeated 10 times.

2.High temperature and high humidity test Left for 500 hours at 70 ° C and 80% environment.

3. Organic solvent test Rub 40 times with a cloth soaked in alcohol with a force of 2kg.

 The results are shown below.

As described above, the film configuration according to the present invention was satisfactory with respect to the organic solvent.

Effect of the Invention By interposing a YF ₃ layer and a metal Cr layer between a substrate and a multilayer film according to the present invention, a synthetic resin optical substrate or a glass substrate can be manufactured with durability such as solvent resistance and environmental resistance, and adhesion. Thus, a multilayer film having excellent film strength can be formed.

[Brief description of the drawings]

FIGS. 1, 2, 4 and 5 are diagrams showing the reflectance of the antireflection film. FIG. 3 is a diagram showing the spectral characteristics of the half mirror.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-252301 (JP, A) JP-A-61-56301 (JP, A) JP-A-64-15703 (JP, A) JP-A-62 186202 (JP, A) JP-A-61-183603 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 1/10-1/12 G02B 5/20-5/28 G02B 5/08-5/10

Claims (1)

(57) [Claims] 1. A multilayer film for an optical component, comprising, in order, a layer made of metallic Cr having a thickness of 100 ° or less and a layer made of YF ₃ having a thickness of 500 ° or more on a resin substrate.