JP2691651B2 - Reflector - Google Patents

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 formed by depositing a silver film 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 terms of 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 characteristic is 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 is a problem that the spectral reflection characteristics at (400 to 500 nm) are deteriorated.

There has also been a strong demand for strengthening the adhesion between the silver layer and the substrate when laminating the silver layer on the substrate.
The present invention has been made in view of the above circumstances. Even when a protective layer is provided on the silver layer, it is possible to prevent the deterioration of the spectral reflection characteristics and to enhance the adhesion between the substrate and the silver layer. The purpose is to provide a mirror.

[0008]

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

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]

Embodiments of the present invention will be described below.

FIG. 1 is a schematic view showing the layer structure of a reflecting mirror according to an embodiment of the present invention. This reflecting mirror comprises a Cr layer 2 having a thickness of 5 to 15 nm, a Cu layer 3 having a thickness of 10 to 40 nm,
m-thick Ag layer 4, 69 nm-thick Al ₂ O ₃ layer 5, 57 nm-thick 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 the film. 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 abrasion 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, 10 to 40 nm thick C is deposited on the Cr layer 2 by using a resistance heating evaporation method.
The u layer 3 is formed.

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

After that, the vacuum chamber is placed in the glass substrate 1.
Is heated to a temperature of 300 ° C. By this heat treatment, the ZrO ₂ layer 6 and SiO ₂
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, such as 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 SiO ₂ 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,
For those using the resistance heating evaporation method, 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 reflectance characteristics 3
The curves are represented. The curve marked with the symbol S shows the reflectance of the S component, the curve marked 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 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 on a cleaned glass substrate to fabricate 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 conversely, 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, the Cr layer and the Cu layer are laminated in this order between the substrate and the silver layer to enhance the adhesion between the substrate and the silver layer. You can Further, since the high refractive index dielectric layer is formed on the silver layer and the aluminum oxide layer, the spectral reflection characteristic can be made good over the entire visible range.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a layer configuration 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)

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