JPH05127004A - Reflecting mirror - Google Patents

Abstract

PURPOSE:To improve the spectral reflectivity of the silver reflecting mirror having a protective layer. CONSTITUTION:This reflecting mirror is obtained by laminating a Cr layer 2 having 5-15nm thickness, a Cu layer 3 having 10-40nm thickness, an Ag layer 4 having 100nm thickness, an Al2O3 layer 5 having 69nm thickness, a ZrO2 layer 6 having 57nm thickness and an SiO2 layer 7 having 20nm thickness on a glass substrate 1 in this order. The Cr layer 2 and Cu layer 3 are used to increase the adhesion between the substrate 1 and the Ag layer 4. The incident light is reflected by the layer 4, and the Al2O3 layer 5 is a protective layer to improve the durability of the Ag layer 4. The ZrO2 layer 6 is a high- refractive-index dielectric layer to improve the reflectivity, and spectral reflectivity is improved by this layer. Meanwhile, the wear resistance is improved by the uppermost SiO2 layer 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflector used in various optical systems, and more particularly to a silver reflector having a silver layer.

[0002]

2. Description of the Related Art As a reflecting mirror used in various optical systems, a silver reflecting mirror having a silver film deposited on a substrate is known.

Silver reflectors have attracted attention because they have a high reflectance in the visible light region and are superior in spectral reflection characteristics as compared with aluminum reflectors, and also in polarization characteristics.

The silver reflecting mirror has such advantages, but has a problem in strength such as durability. Therefore, it is known that a protective layer made of aluminum oxide or the like is provided on the silver layer.

[0005]

However, when the above-mentioned protective layer is provided on the silver layer, there is a problem that the spectral reflection characteristics are significantly deteriorated.

If the layer thickness of the aluminum oxide layer is increased to about 200 nm, it is possible to improve the spectral reflection characteristics on the long wavelength side (500 nm or more) in the visible region, but on the other hand, on the short wavelength side in the visible region. There was a problem that the spectral reflection characteristics at (400 to 500 nm) deteriorate.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reflecting mirror capable of preventing deterioration of spectral reflection characteristics even when a protective layer is provided on a silver layer. ..

[0008]

The reflecting mirror of the present invention is characterized in that a silver layer, an aluminum oxide layer and a high refractive index dielectric material layer are laminated in this order on a substrate.

Here, the substrate, the silver layer, the aluminum oxide layer, and the high-refractive-index dielectric material layer may be provided directly, or another layer may be provided between them.

The high-refractive-index dielectric material means a dielectric material having a refractive index of 1.9 or more, such as ZrO ₂ , TiO ₂ , and Z.
nS etc. are included.

[0011]

EXAMPLES Examples of the present invention will be described below.

FIG. 1 is a schematic view showing a layer structure of a reflecting mirror according to an embodiment of the present invention. This reflector is composed of a Cr layer 2 having a thickness of 5 to 15 nm, a Cu layer 3 having a thickness of 10 to 40 nm, and 100 n on a glass substrate 1.
m Ag layer 4, 69 nm Al ₂ O ₃ layer 5, 57 nm Z
rO ₂ (zirconium oxide, refractive index 1.98) layers 6 and 20
A SiO ₂ layer 7 having a thickness of nm is laminated in this order.

The Cr layer 2 and the Cu layer 3 act as an adhesion strengthening layer for strengthening the adhesion between the glass substrate 1 and the Ag layer 4. Further, the Ag layer 4 is a layer for reflecting incident light, and the Al ₂ O ₃ layer 5 is the Ag layer 4
Is a protective layer for improving the durability of. Also, Zr
The O ₂ layer 6 is a protective layer for improving the durability of the Ag layer 4 and a high refractive index dielectric layer for improving the reflection characteristics. Further, the uppermost SiO ₂ layer 7 is a protective layer for improving wear resistance.

Next, a method for manufacturing the reflecting mirror having the layer structure shown in FIG. 1 will be described.

First, the cleaned glass substrate 1 is attached to a holder, which is inserted and fixed in a vacuum chamber. The inside of the vacuum chamber is evacuated without heating to about 1 × 10 ^-6 Torr.

After that, the Cr layer 2 having a thickness of 5 to 15 nm is formed on the glass substrate 1 by using the electron beam evaporation method. Next, using a resistance heating vapor deposition method, C of 10 to 40 nm thickness is formed on the Cr layer 2.
The u layer 3 is formed.

After that, the Cu film is formed by resistance heating vapor deposition.
A 100 nm thick Ag layer 4 is formed on the layer 3. Next, using an electron beam evaporation method, a 69 nm thick Al ₂ O film was formed on the Ag layer 4.
₃ Layer 5 is formed.

After that, the vacuum chamber is placed in the glass substrate 1.
Heat so that the temperature becomes 300 ℃. By this heat treatment, the ZrO ₂ layer 6 and SiO ₂ formed thereafter are formed.
The strength of the layer 7 can be increased.

If the heat treatment is performed before this, the metal layers such as the Ag layer 4 and the Cu layer 3 are crystallized to cause a clouding phenomenon (white turbidity), which lowers the light reflectance, which is not preferable.

After that, the above-mentioned A
A 57 nm thick ZrO ₂ layer 6 is formed on the l ₂ O ₃ layer 5.

Finally, using the electron beam evaporation method, this Z
A SiO ₂ layer 7 having a thickness of 20 nm is formed on the rO ₂ layer 6.

The reflecting mirror of the present invention is not limited to the above-mentioned embodiment.

For example, the ZrO ₂ layer 6 is a layer made of another high refractive index dielectric material having a refractive index (refractive index of sodium D line) of 1.9 or more, for example, TiO ₂ (titanium oxide, refractive index 2.3.
) Layer or a ZnS (zinc sulfide, refractive index 2.37) layer.

Further, the glass substrate 1 can be replaced with a metal substrate, and the SiO ₂ layer 7 can be replaced with a layer made of another substance having high abrasion resistance, for example, a MgF ₂ layer.

Further, the Cr layer 2, Cu layer 3 and SiO ₂
The layer 8 can be omitted as appropriate.

Further, the vapor deposition method for forming each layer is not limited to the above-mentioned method. For example, in the above-mentioned explanation, in the case where the electron beam vapor deposition method is used for forming the layers, resistance heating is used instead thereof. A vapor deposition method may be used,
If the resistance heating evaporation method is used, an electron beam evaporation method may be used instead.

Next, the following Examples 1-3 and Comparative Example 1,
2 to 6 show the spectral reflection characteristics in each case of No. 2 and Table 1 shows the reflectance when the wavelength of the incident light is 400 nm, 500 nm and 700 nm.

2 to 6 show spectral reflection characteristics 3
The curves of the book are represented. The curve with the symbol S shows the reflectance of the S component, the curve with the symbol P shows the reflectance of the P component, and the curve located between these two curves is S.
It is a curve showing the average value of the reflectance of both the component and the P component, and the values shown in Table 1 are also based on the curve showing this average value.

Example 1 A 500 nm thick Ag layer, a 69 nm thick Al ₂ O ₃ layer, a 57 nm thick ZrO ₂ layer and a 20 nm thick S layer were deposited on a cleaned glass substrate.
A reflective mirror was manufactured by stacking iO ₂ layers in this order.

The spectral reflection characteristics are shown in FIG.

Example 2 A 500 nm thick Ag layer, a 69 nm thick Al ₂ O ₃ layer, a 45 nm thick TiO ₂ layer and a 20 nm thick Si layer on a cleaned glass substrate.
A reflective mirror was manufactured by stacking O ₂ layers in this order.

Spectral reflection characteristics are shown in FIG.

Example 3 A 500 nm thick Ag layer, a 69 nm thick Al ₂ O ₃ layer, a 49 nm thick ZnS layer and a 20 nm thick SiO layer were formed on a cleaned glass substrate.
_Two layers were laminated in this order to manufacture a reflecting mirror.

Spectral reflection characteristics are shown in FIG.

Comparative Example 1 A reflecting mirror was manufactured by laminating a 500 nm thick Ag layer, a 69 nm thick Al ₂ O ₃ layer and a 20 nm thick SiO ₂ layer in this order on a cleaned glass substrate.

Spectral reflection characteristics are shown in FIG.

Comparative Example 2 On a cleaned glass substrate, a 500 nm thick Ag layer, a 138 nm thick Al ₂ O ₃ layer and a 20 nm thick SiO ₂ layer were laminated in this order to manufacture a reflecting mirror.

The spectral reflection characteristics are shown in FIG.

[0039]

[Table 1]

As shown in Table 1 and FIGS. 2 to 6, each of Examples 1 to 3 has a long wavelength side (500n) in the visible region.
High reflectivity at wavelengths above m) and short wavelength side (400 to 50
Even at 0 nm), it shows a high reflectance to some extent.

On the other hand, Comparative Example 1 does not show such a high reflectance on the long wavelength side in the visible region, and on the contrary, Comparative Example 2 significantly reduces the reflectance on the short wavelength side in the visible region. To do.

[0042]

As described above, according to the reflecting mirror of the present invention, since the high refractive index dielectric layer is formed on the Ag layer and the Al ₂ O ₃ layer, it is possible to cover the entire visible range. Spectral reflection characteristics can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a layer structure of a reflecting mirror according to an embodiment of the present invention.

FIG. 2 is a graph showing the spectral reflection characteristics of the reflecting mirror of Example 1.

FIG. 3 is a graph showing the spectral reflection characteristics of the reflecting mirror of Example 2.

FIG. 4 is a graph showing the spectral reflection characteristics of the reflecting mirror of Example 3;

FIG. 5 is a graph showing the spectral reflection characteristics of the reflecting mirror of Comparative Example 1.

FIG. 6 is a graph showing the spectral reflection characteristics of the reflecting mirror of Comparative Example 2.

[Explanation of symbols]

1 Glass Substrate 2 Cr Layer 3 Cu Layer 4 Ag Layer 5 Al ₂ O ₃ Layer 6 ZrO ₂ Layer 7 SiO ₂ Layer

Claims (1)

[Claims] 1. A reflecting mirror comprising a silver layer, an aluminum oxide layer and a high refractive index dielectric layer laminated in this order on a substrate.