JP2001264523A - Reflection mirror - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a reflection mirror at a low cost having >=90% reflectance in the wavelength region from 600 to 1,000 nm. SOLUTION: A gold film having 1 to 70 nm physical film thickness and an aluminum film having >=10 nm physical film thickness are formed on a substrate. The reflectance is improved by the gold film and the mirror can be manufactured at a low cost by forming the aluminum film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a camera, a microscope,
The present invention relates to a reflector used for an optical device such as a bar code reader.

[0002]

2. Description of the Related Art A reflecting mirror used in an optical apparatus is constituted by providing a reflecting film of a reflective metal such as gold or aluminum on the surface of a substrate made of glass or resin. Conventional reflecting mirrors are described in JP-A-8-54504 and JP-A-5-281405.

The reflecting mirror described in Japanese Patent Application Laid-Open No. 8-54504 has a two-layer structure of a base layer made of chromium and a reflective layer made of gold having a physical thickness of 150 nm or more formed on the base layer. ing. On the other hand, the reflecting mirror described in Japanese Patent Application Laid-Open No. 5-281406 uses aluminum. An underlying layer made of silicon dioxide, a reflecting layer made of aluminum formed on the underlying layer, and It has a three-layer structure of the formed protective layer made of silicon dioxide.

[0004]

Problems to be Solved by the Invention Japanese Patent Application Laid-Open No. 8-54504
In addition to using expensive gold, the reflecting mirror disclosed in Japanese Patent Application Laid-Open No. H10-15064 forms a film with a physical thickness of 150 nm or more.
There is a problem that the product cost of the reflecting mirror is high.

The reflecting mirror disclosed in Japanese Patent Application Laid-Open No. 5-281406 can be inexpensive because aluminum is used. However, compared to a reflecting mirror using gold, the reflecting mirror is 800 nm to 10 nm.
In the wavelength region of 00 nm, there is a problem that the reflectance is as low as 90% or less. For example, at a wavelength of 800 nm, the reflectance is 86.0%, and such a reflectance is not practical.

The present invention has been made in consideration of such a conventional problem, and is inexpensive.
It is an object of the present invention to provide a reflector having a high reflectance of 90% or more in a wavelength region of 1000 nm.

[0007]

In order to achieve the above-mentioned object, according to the present invention, a gold film having a physical thickness of 1 to 70 nm and an aluminum film having a physical thickness of 10 nm or more are formed on a substrate. It is characterized by being.

A second aspect of the present invention provides a gold film having a physical film thickness of 5 to 70 nm and a physical film thickness of 10 n from the light incident direction of the optical system.
m or more aluminum films are sequentially formed on the substrate.

According to a third aspect of the present invention, an aluminum film having a physical thickness of 10 nm or more and a gold film having a physical thickness of 1 to 70 nm are sequentially formed on a substrate from the light incident direction of the optical system. I do.

In these inventions, since a gold film is present,
The reflectance is 90% or more in the wavelength range of 600 to 1000 nm. Further, since the aluminum film is stacked, it is not necessary to increase the thickness of the gold film, and the amount of gold used can be reduced. Further, the reflectance is higher in the wavelength region of less than 600 nm than in the case of using only the gold film, so that it is practical also in the wavelength region of less than 600 nm.

In these inventions, the physical thickness of the gold film is 1 to 70 nm. If the physical thickness of the gold film is less than 1 nm, the reflectivity to light rays is lowered, which is not preferable. If the physical thickness is more than 70 nm, the amount of gold used increases, and the cost rises. . As the gold film, a physical film thickness in the range of 7 to 40 nm is more preferable.

The aluminum film is interposed between the substrate and the gold film to support the gold film or is provided on the gold film to protect the gold film. In any of these cases, the physical thickness of the aluminum film is 10 nm or more. It is not preferable to form a film having a thickness of less than 10 nm as the supporting layer for the gold film, because the gold film cannot be favorably supported. On the other hand, if the film thickness is less than 10 nm is formed as the protective layer of the gold film, it is not preferable because the gold film cannot be reliably protected. In this case, the thickness of the aluminum film is particularly preferably from 10 nm to 60 nm.

These gold and aluminum films are formed by
It can be performed by an appropriate means such as vacuum deposition, ion plating, sputtering and the like. In these inventions, an aluminum film or a gold film may be formed after forming a base film on a substrate, or a protective film may be formed on an aluminum film or a gold film formed on a substrate. May be. An inorganic oxide such as SiO ₂ can be used as a material for the base film and the protective film.

In the above invention, as the substrate on which the gold film and the aluminum film are formed, those used in accordance with various optical parts can be used. For example, a glass substrate or a resin substrate such as a polycarbonate resin or an acrylic resin can be selected. When a glass substrate or a resin substrate is used as described above, it is useful as a reflecting mirror as an optical component. In the above invention, a light beam may be incident from the back surface of the substrate on which the gold film and the aluminum film are not formed. In this case, the light beam has a reflectance of 90% or more in the above-mentioned wavelength range. Therefore, light rays can be surely reflected.

[0015]

(Embodiment 1) As shown in Table 1, in this embodiment, BK7 (manufactured by Schott) is used.
An aluminum film is formed with a physical thickness of 30 nm on a glass substrate made of
A gold film was formed with a physical thickness of. Film formation heats the substrate,
This was performed by a vacuum deposition method. Note that formation of these thin films can also be performed by ion plating or sputtering for forming an inorganic substance such as a metal oxide.

As shown in Table 1, as Comparative Example 1, an aluminum film was formed with a physical thickness of 100 nm on a substrate made of BK7, and as Comparative Example 2, a gold film was formed on a substrate made of BK7. Was formed with a physical thickness of 100 nm.
These films were formed in the same manner as in the first embodiment.

[0017]

[Table 1]

FIG. 1 shows the spectral reflectance characteristics of this embodiment and a comparative example. A characteristic curve a is that of this embodiment, a characteristic curve b is that of comparative example 1, and a characteristic curve c is that of comparative example 2. In this embodiment, 92.6% at a wavelength of 600 nm and a wavelength of 8
The reflectance is as high as 95.3% at 00 nm, and 60%.
In the wavelength range of 0 to 1000 nm, a high reflectance of 90% or more can be obtained.

On the other hand, the reflectance characteristics of Comparative Example 1 were 92.1% at a wavelength of 500 nm and 91.0% at a wavelength of 600 nm.
%, Which is 86.4% at a wavelength of 800 nm. The first embodiment composed of an aluminum film and a gold film has a higher reflectance in a wavelength region of 600 nm or more than Comparative Example 1 in which only an aluminum film is used. I have. On the other hand, the reflectance characteristics of Comparative Example 2 were 50.9% at a wavelength of 500 nm and a wavelength of 600 n.
m is 91.4%, the wavelength is 800 nm, 97.3%,
The first embodiment composed of an aluminum film and a gold film can obtain the same high reflectance in a wavelength region of 600 nm or more, as compared with Comparative Example 2 composed of only a gold film.
Compared with, since the amount of gold used is small, it can be produced at low cost and can be used as an optical component in a wide range. Although not shown, in the first embodiment, even when a light beam is incident from the back surface of the substrate, the reflectance has substantially the same as the characteristic curve a.

(Embodiment 2) As shown in Table 2, in this embodiment, a gold film having a physical thickness of 30 nm is formed on a glass substrate made of BK7 (manufactured by Shot Co., Ltd.). An aluminum film having a physical thickness of 30 nm was formed on the gold film. The film was formed by heating the substrate and using a vacuum evaporation method. These thin films can also be formed by ion plating or sputtering for forming an inorganic substance such as a metal oxide. If it is necessary to further improve the adhesion of the gold film to the substrate,
This can be achieved by forming a contact metal such as chromium (Cr) between the substrate and the gold film.

As shown in Table 2, as Comparative Example 3, BK
An aluminum film having a physical thickness of 100 on a substrate made of
As Comparative Example 4, a gold film was formed on a substrate made of BK7 with a physical thickness of 100 nm. These films were formed in the same manner as in the second embodiment.

[0022]

[Table 2]

FIG. 2 shows the spectral reflectance characteristics of this embodiment and the comparative example. The characteristic curve d is for this embodiment, the characteristic curve e is for Comparative Example 3, and the characteristic curve f is for Comparative Example 4. In this embodiment, 90.0% at a wavelength of 600 nm and a wavelength of 8
The reflectance is as high as 93.3% at 00 nm, and 60%.
In the wavelength range of 0 to 1000 nm, a high reflectance of 90% or more can be obtained.

On the other hand, the reflectance characteristics of Comparative Example 3 were 88.1% at a wavelength of 500 nm and 91.0% at a wavelength of 600 nm.
%, 80.8% at a wavelength of 800 nm, and the second embodiment composed of the aluminum film and the gold film has a higher reflectance in a wavelength region of 600 nm or more than the comparative example 3 in which only the aluminum film is used. I have. On the other hand, the reflectance characteristics of Comparative Example 4 were 44.8% at a wavelength of 500 nm and a wavelength of 600 n.
m is 88.7%, the wavelength is 800 nm, 96.2%,
The second embodiment composed of the aluminum film and the gold film can obtain the same high reflectivity in the wavelength region of 600 nm or more as compared with the comparative example 4 composed of only the gold film.
Compared with, since the amount of gold used is small, it can be produced at low cost and can be used as an optical component in a wide range. Further, also in the second embodiment, even when a light beam is incident from the back surface of the substrate, the reflectivity is substantially the same as the characteristic curve d.

(Embodiment 3) As shown in Table 3, in this embodiment, a resin substrate made of ZEONEX (trade name, manufactured by Nippon Zeon Co., Ltd.)
_Two films were formed with a physical thickness of 10 nm, an aluminum film was formed thereon with a physical thickness of 30 nm, and a gold film was formed on this aluminum film with a physical thickness of 30 nm.
The film was formed by a vacuum evaporation method without heating the substrate. Note that formation of these thin films can also be performed by ion plating or sputtering for forming an inorganic substance such as a metal oxide.

As shown in Table 3, as Comparative Example 5, ZE
On a resin substrate made of ONEX, SiO _{2 is used} as an underlayer.
A film was formed with a physical thickness of 10 nm, and an aluminum film was formed thereon with a physical thickness of 100 nm. Further, as Comparative Example 6, an SiO ₂ film was formed as a base layer with a physical thickness of 10 nm on a resin substrate made of ZEONEX, and a gold film was formed thereon with a physical thickness of 100 nm. These films were formed in the same manner as in the third embodiment.
In the case of Comparative Example 6, a contact metal such as chromium was formed between the SiO ₂ film and the gold film.

[0027]

[Table 3]

FIG. 3 shows the spectral reflectance characteristics of this embodiment and the comparative example. The characteristic curve g is that of this embodiment, the characteristic curve h is that of Comparative Example 5, and the characteristic curve i is that of Comparative Example 6. In this embodiment, 90.0% at a wavelength of 600 nm and a wavelength of 8
The reflectance is as high as 95.0% at 00 nm, and 60%.
In the wavelength range of 0 to 1000 nm, a high reflectance of 90% or more can be obtained. Further, in this embodiment, a test of the adhesive strength of the film was performed. The adhesion strength test is to adhere a cellophane tape (manufactured by NICHIBAN (trademark)) to the surface of the film, and then peel off the cellophane tape (registered trademark) directly upward to observe the peeling state of the film. As a result, no peeling occurred.

On the other hand, the reflectance characteristics of Comparative Example 5 were 92.1% at a wavelength of 500 nm and 91.0% at a wavelength of 600 nm.
%, And 86.4% at a wavelength of 800 nm.
Has a higher reflectance in the wavelength region of 600 nm or more than that of Comparative Example 5. On the other hand, the reflectance characteristics of Comparative Example 6 are as follows:
50.9% at a wavelength of 500 nm;
4%, and 97.3% at a wavelength of 800 nm. In the third embodiment, a comparable high reflectance is obtained in a wavelength region of 600 nm or more even in comparison with Comparative Example 6. Moreover, when compared with Comparative Example 6, the amount of gold used is small, so that it can be produced at low cost and can be widely used as an optical component.

(Embodiment 4) As shown in Table 4, in this embodiment, a gold film having a physical thickness of 30 nm was formed on a resin substrate made of ZEONEX (trade name, manufactured by Zeon Corporation). A 30 nm thick aluminum film is formed on this
Physically film formed to a thickness of, and a SiO ₂ film by a physical film thickness of 10nm as a protective layer on the aluminum film.
The film was formed by a vacuum evaporation method without heating the substrate. Note that formation of these thin films can also be performed by ion plating or sputtering for forming an inorganic substance such as a metal oxide. In this case, if it is necessary to further improve the adhesion of the gold film to the substrate, this can be achieved by forming a contact metal such as chromium (Cr) between the substrate and the gold film. In the case of Comparative Example 8, a contact metal such as chromium was formed between the SiO ₂ film and the gold film.

As shown in Table 4, as Comparative Example 7, ZE
On a resin substrate made of ONEX, an aluminum film is
A physical thickness of 0 nm, and S
iO ₂The film was formed with a physical thickness of 10 nm. Also, the ratio
As Comparative Example 6, gold was placed on a resin substrate made of ZEONEX.
A film is formed with a physical thickness of 100 nm, and a protective layer is formed thereon.
As SiO₂The film was formed with a physical thickness of 10 nm.
Note that these films are formed in the same manner as in Embodiment 4.
Was.

[0032]

[Table 4]

FIG. 4 shows the spectral reflectance characteristics of this embodiment and the comparative example. The characteristic curve k is for this embodiment, the characteristic curve m is for Comparative Example 7, and the characteristic curve n is for Comparative Example 8. In this embodiment, 90.0% at a wavelength of 600 nm and a wavelength of 8
The reflectance is as high as 93.3% at 00 nm, and 60%.
In the wavelength range of 0 to 1000 nm, a high reflectance of 90% or more can be obtained.

On the other hand, the reflectance characteristic of Comparative Example 7 was 88.1% at a wavelength of 500 nm and 91.0% at a wavelength of 600 nm.
%, And 80.8% at a wavelength of 800 nm.
Has a higher reflectance in the wavelength region of 600 nm or more than that of Comparative Example 7. On the other hand, the reflectance characteristics of Comparative Example 8 are as follows:
44.8% at a wavelength of 500 nm, 88.8 at a wavelength of 600 nm.
7% and 96.2% at a wavelength of 800 nm, and the same high reflectivity is obtained in the fourth embodiment in the wavelength region of 600 nm or more even in comparison with Comparative Example 8. Moreover, when compared with Comparative Example 8, the amount of gold used is small, so that it can be produced at low cost and can be widely used as an optical component.

In the above first to fourth embodiments, FIG.
As shown in FIG. 4 to FIG. 4, the reflectance is higher in the wavelength range of less than 600 nm than in the case where only the gold film is used.
For this reason, the first to fourth embodiments are practical even in a wavelength range of less than 600 nm.

[0036]

As described above, according to any one of the first to third aspects of the present invention, it is possible to obtain a high reflectance of 90% or more in a wavelength region of 600 nm to 1000 nm and to manufacture it at low cost. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a spectral reflectance characteristic diagram of Embodiment 1, Comparative Examples 1 and 2.

FIG. 2 is a spectral reflectance characteristic diagram of a second embodiment, comparative examples 3 and 4.

FIG. 3 is a spectral reflectance characteristic diagram of a third embodiment, comparative examples 5 and 6;

FIG. 4 is a spectral reflectance characteristic diagram of a fourth embodiment, comparative examples 7 and 8;

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ken Kawamata 2-43-2 Hatagaya, Shibuya-ku, Tokyo F-term in Olympus Optical Co., Ltd. (reference) 2H042 DA02 DA05 DA11 DA12 DA15 DC02 DE09

Claims (3)

[Claims] 1. A reflector comprising a gold film having a physical thickness of 1 to 70 nm and an aluminum film having a physical thickness of 10 nm or more formed on a substrate. 2. A physical film thickness of 1 from a light incident direction of an optical system.
A reflector comprising a gold film having a thickness of 70 nm and an aluminum film having a physical thickness of 10 nm or more formed in this order on a substrate. 3. A physical film thickness of 1 from the light incident direction of the optical system.
Aluminum film of 0 nm or more, physical thickness 1-70 nm
Wherein the gold films are sequentially formed on a substrate.