JP2007148037A - Antireflection film and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film which is thin, has an excellent antireflection effect for incident light from visible light region up to near infrared region and is optimum for a substrate made of high refractive index material. <P>SOLUTION: The antireflection film 100 has a three-layer composition comprising: a substrate 110; a first layer 101 laminated on the substrate 110; a second layer 102 laminated on the first layer 101; and a third layer 103 laminated on the second layer 102. The substrate 110 is made of high refractive index material in which the refractive index at design center wavelength 510 nm is approximately 2.0 to 2.4. The first layer 101 is made of material in which the refractive index at design center wavelength 510 nm is approximately 1.65. The second layer 102 is made of material in which the refractive index at design center wavelength 510 nm is approximately 2.10. The third layer 103 is made of material in which the refractive index at design center wavelength 510 nm is approximately 1.38. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an antireflection film optimum for a high refractive index optical element such as various lenses and a method for manufacturing the same.

  Optical elements such as lenses, prisms, and filters that are widely used in cameras, projectors, and the like reflect several percent of incident light on their surfaces, so that the efficiency of use of incident light is reduced, leading to image degradation. Therefore, in order to improve the utilization efficiency of incident light and prevent image deterioration, generally, an antireflection film for light is formed on the optical element surface.

Such an antireflection film is formed by laminating a plurality of layers made of materials having different refractive indexes. For example, using Al ₂ O ₃ (aluminum oxide), ZrO ₂ (zirconium oxide), MgF ₂ (magnesium fluoride), etc., a plurality of layers having refractive indexes different from low, medium and high are formed, and each layer has a predetermined optical property. It is comprised so that it may become a target film thickness. In particular, in recent years, antireflection films suitable for increasing the refractive index of various optical elements have been proposed (see, for example, Patent Documents 1 and 2 below).

  For example, the antireflection film described in Patent Document 1 includes a first layer, a third layer, and a sixth layer, which are high refractive index layers having a refractive index lower than that of the substrate, and a medium refractive index layer or a low refractive index layer. This is a six-layered alternating multilayer film composed of two layers, a fourth layer, and a sixth layer which is a low refractive index layer. The optical film thickness of each layer is also optimized, and the reflectance is about 0.5% or less over the entire visible light region.

  In addition, the antireflection film described in Patent Document 2 is configured by laminating an intermediate refractive index layer, a high refractive index layer, and a low refractive index layer in order from the bottom. In particular, the intermediate refractive index layer is formed of a mixed material with the material forming the high refractive index layer, and the peak value of the reflectance in the visible light region is small without being affected by the refractive index of the substrate, and excellent antireflection It has characteristics.

JP 2000-347002 A JP 2003-202405 A

  However, since the antireflection film described in Patent Document 1 has a six-layer structure, the film thickness is increased. In addition, since the antireflection film has a multilayer structure, a large amount of materials are required and the number of steps for forming the film increases, leading to a problem of high costs. Further, the antireflection effect is exhibited only in the visible light region. There is also a problem that the antireflection effect cannot be expected when formed on a substrate made of a high refractive index material.

  The antireflection film described in Patent Document 2 also exhibits the antireflection effect only in the visible light region. In particular, since the antireflection effect in the near infrared region (wavelength 1000 nm) is not considered at all, the antireflection effect equivalent to the visible light region cannot be expected at all in the near infrared region. Specifically, there is a problem that the reflectance of incident light increases rapidly in the near infrared region, and the reflectance in the near infrared region cannot be suppressed to 4% or less.

  From the above, it can be said that the conventional antireflection film has the following problems. That is, (1) since there are many film layers constituting the antireflection film, various materials are required, resulting in an increase in cost. (2) When formed on a substrate formed of a high refractive index material, it is difficult to reduce the reflectance of incident light. (3) Only an antireflection effect for light in the visible light region can be expected, and an antireflection effect for light in the near infrared region cannot be obtained. (4) The film thickness is increased due to the multilayer structure, which takes time and effort.

  In order to eliminate the above-mentioned problems caused by the prior art, the present invention has an excellent antireflection effect on incident light from the visible light region to the near infrared region, and is a thin substrate made of a high refractive index material. An object is to provide an optimal antireflection film and a method for manufacturing the same. It is another object of the present invention to provide an antireflection film that has an excellent antireflection effect on incident light and can reduce the manufacturing cost, and a method for manufacturing the same.

  In order to solve the above-described problems and achieve the object, the antireflection film according to the invention of claim 1 is made of a high refractive index material having a refractive index at a design center wavelength of about 2.0 to about 2.4. A first layer having a refractive index at a design center wavelength of about 1.65, which is lower than a refractive index of the substrate, and a refractive index at a design center wavelength, laminated on the first layer. A second layer having a refractive index of about 2.10, which is approximately the same as the refractive index of the substrate, and a refractive index at a design center wavelength laminated on the second layer are higher than those of the substrate, the first layer, and the second layer. And a third layer, which is about 1.38, which is low.

  According to the first aspect of the present invention, a thin three-layer structure, which is optimal for formation on a substrate made of a high refractive index material having a refractive index at a design center wavelength of about 2 or more, is effective from the visible light region to the near red region. It is possible to provide an antireflection film having an excellent antireflection effect capable of suppressing the reflectance of light to the outer region to about 0.5 to about 4.5 percent or less. In addition, an inexpensive antireflection film with a simple configuration can be provided.

The reflection preventing film according to the invention of claim 2 is the invention according to claim 1, when the design center wavelength and lambda _0, the optical thickness of about 0.027Ramuda ₀ of the first layer To about 0.055λ ₀ , the optical thickness of the second layer is about 0.041λ ₀ to about 0.077λ ₀ , and the optical thickness of the third layer is about 0.189λ ₀ to about 0.0. characterized in that set to be 201λ _0.

  According to the invention of the second aspect, the effect of the invention of the first aspect can be realized by a film formed to be thinner.

The antireflection film according to the invention of claim 3 is an optical film laminated on a substrate made of a high refractive index material having a refractive index at a design center wavelength of about 2.0 to about 2.4. A first layer made of a medium refractive index material having a thickness of about 0.027λ ₀ to about 0.055λ ₀ (λ ₀ is a design center wavelength) and a refractive index at the design center wavelength lower than the refractive index of the substrate; The optical film thickness is about 0.041λ ₀ to about 0.077λ ₀ laminated on the first layer, and is made of a high refractive index material whose refractive index at the design center wavelength is substantially equal to the refractive index of the substrate. An optical film thickness laminated on the second layer and the second layer is about 0.189λ ₀ to about 0.201λ ₀ , and a refractive index at a design center wavelength is the substrate, the first layer, and the And a third layer made of a low refractive index material lower than the refractive index of the second layer. It is characterized in.

  According to the third aspect of the invention, a thin three-layer structure, which is optimal for forming on a substrate made of a high refractive index material having a refractive index at a design center wavelength of about 2 or more, is effective from the visible light region. It is possible to provide an antireflection film having an excellent antireflection effect capable of suppressing the reflectance of light to the outer region to about 0.5 to about 4.5 percent or less.

  According to a fourth aspect of the present invention, in the antireflection film according to the third aspect of the present invention, the refractive index at the design center wavelength of the first layer is about 1.65, and the design center wavelength of the second layer. The refractive index of the third layer is about 2.10, and the refractive index at the design center wavelength of the third layer is about 1.38.

  According to the fourth aspect of the present invention, a thin three-layer structure having a refractive index at a design center wavelength of approximately 2 or more, which is optimal for forming on a substrate made of a high refractive index material, is effective from the visible light region. It is possible to provide an antireflection film having an excellent antireflection effect capable of suppressing the reflectance of light to the outer region to about 0.5 to about 4.5 percent or less.

The antireflection film according to the invention described in claim 5 is the antireflection film according to any one of claims 1 to 4, wherein the substrate is made of a high refractive index glass material or a ceramic material, and the first layer. Is made of Al ₂ O ₃ (aluminum oxide), the second layer is made of a mixture of ZrO ₂ (zirconium oxide) and TiO ₂ (titanium oxide) in a ratio of 6: 1, and the third layer is made of characterized in that it consists of MgF ₂ (magnesium fluoride).

  According to the fifth aspect of the present invention, the antireflection film according to any one of the first to fourth aspects can be made of an inexpensive material.

The antireflection film according to the invention described in claim 6 has an optical film thickness of 0.039λ laminated on a substrate made of a high refractive index ceramic material having a refractive index of 2.20 at the design center wavelength. _A first layer made of Al ₂ O ₃ (aluminum oxide) that is ₀ (λ ₀ is a design center wavelength) and has a refractive index at the design center wavelength of 1.65 lower than the refractive index of the substrate; ZrO ₂ (zirconium oxide) and TiO ₂ (stacked on top of each other) have an optical film thickness of 0.058λ ₀ and a refractive index at the design center wavelength of 2.10, which is substantially the same as the refractive index of the substrate. And a second layer made of a material mixed with titanium oxide at a ratio of 6: 1, an optical film thickness of 0.192λ ₀ laminated on the second layer, and a refractive index at the design center wavelength. Is a bending of the substrate, the first layer and the second layer. Characterized in that it is constituted a third layer of MgF ₂ (magnesium fluoride) is lower than the rate 1.38, the.

  According to the sixth aspect of the present invention, a thin three-layer structure, which is optimal for formation on a substrate made of a high refractive index material having a refractive index at a design center wavelength of about 2 or more, is effective from the visible light region. It is possible to provide an antireflection film having an excellent antireflection effect capable of suppressing the reflectance of light to the outer region to about 0.5 to about 4.5 percent or less. Moreover, the antireflection film can be made of an inexpensive material.

  According to a seventh aspect of the present invention, there is provided a method for producing an antireflection film, comprising: a substrate made of a high refractive index material having a refractive index at a design center wavelength of about 2.0 to about 2.4; A first layer laminating step of laminating a first layer having a refractive index of about 1.65 lower than the refractive index of the substrate; and a refractive index at a design center wavelength on the first layer is substantially equal to the refractive index of the substrate. A second layer stacking step of stacking a second layer having an equivalent of about 2.10, and a refractive index at a design center wavelength lower than that of the substrate, the first layer, and the second layer on the second layer; And a third layer laminating step of laminating a third layer of 1.38.

  According to the seventh aspect of the present invention, a thin three-layer structure, which is optimal for forming a film on a substrate made of a high refractive index material having a refractive index of about 2 or more at the design center wavelength, is close to the visible light region. An antireflection film having an excellent antireflection effect capable of suppressing the reflectance of light in the infrared region to about 0.5 to about 4.5 percent or less can be provided. In addition, an inexpensive antireflection film that can be manufactured by a simple process can be provided.

  According to the present invention, there is provided an antireflection film that is optimal for a substrate made of a high refractive index material and that is thin and has an excellent antireflection effect for incident light from the visible light region to the near infrared region. There is an effect that can be. In addition, there is an effect that an inexpensive antireflection film with a simple configuration can be provided.

  Preferred embodiments of an antireflection film and a method for manufacturing the same according to the present invention will be described below in detail with reference to the accompanying drawings.

(Configuration of antireflection film)
FIG. 1 is a sectional view showing the structure of an antireflection film according to an embodiment of the present invention. The antireflection film 100 is laminated on a substrate 110 made of a high refractive index material having a refractive index of about 2.0 to about 2.4 at a design center wavelength of 510 nm, and has a refractive index of about 1 at a design center wavelength of 510 nm. And a second layer (high refractive index layer) 102 having a refractive index of about 2.10 at a design center wavelength of 510 nm, laminated on the first layer 101. And a third layer (low refractive index layer) 103 that is laminated on the second layer 102 and has a refractive index of about 1.38 at a design center wavelength of 510 nm. When the design center wavelength is λ ₀ , the optical thickness of the first layer 101 is about 0.027λ ₀ to about 0.055λ ₀ , and the optical thickness of the second layer 102 is about 0.041λ _0. to about 0.077λ _0, is set as an optical film thickness of the third layer 103 is about 0.189Ramuda ₀ to about 0.201λ _0. The substrate 110 is assumed to be an optical element such as a lens, a prism, or a filter that is widely used in cameras, projectors, and the like.

  The antireflection film 100 is formed by first laminating a first layer 101 on a substrate 110, further laminating a second layer 102 on the first layer 101, and finally laminating a second layer 102 on the second layer 102. It is configured by laminating three layers 103.

  The antireflection film 100 according to this embodiment has a three-layer structure as described above, and provides an excellent antireflection effect for incident light from the visible light region to the right near infrared region. Specifically, the reflectance for incident light in the visible light region with a wavelength of 400 to 700 nm can be suppressed to about 1 percent or less, and particularly the reflectance for incident light with a wavelength of 420 to 650 nm can be suppressed to about 0.5 percent or less. Moreover, the reflectance with respect to incident light in the near infrared region having a wavelength of 800 to 1000 nm can be suppressed to about 2.5 to about 4.5 percent or less.

  Examples of the antireflection film according to the present invention will be described below.

Example 1
First, the detailed configuration of the antireflection film according to Example 1 will be described. The antireflection film 100 according to the first embodiment includes a first layer 101 stacked on the substrate 110, a second layer 102 stacked on the first layer 101, and a third layer stacked on the second layer 102. 3 layers.

The substrate 110 is formed of a glass or ceramic material having a refractive index of 2.00 to 2.40 at a design center wavelength of 510 nm. The first layer 101 is formed of Al ₂ O ₃ (aluminum oxide) so as to be lower than the refractive index of the substrate 110 (refractive index at a design center wavelength of 510 nm is 1.65). The optical film thickness of the first layer 101 is set to 0.027λ _{0 to} 0.055λ ₀ (λ ₀ is the design center wavelength 510 nm). The second layer 102 is a mixture of ZrO ₂ (zirconium oxide) and TiO ₂ (titanium oxide) so as to be higher than the refractive index of the substrate 110 and the third layer 103 (refractive index at a design center wavelength of 510 nm is 2.10). Form with material. The mixing ratio of ZrO ₂ and TiO _{2 at} this time is 6: 1. Then, the optical thickness of the second layer 102 is set to 0.041λ ₀ ~0.077λ _0. The third layer 103 is formed of MgF ₂ (magnesium fluoride) so that the refractive index is the lowest among the layers (the refractive index at the design center wavelength of 510 nm is 1.38). Then, the optical thickness of the third layer 103 is set to 0.189λ ₀ ~0.201λ _0.

Next, characteristics of the antireflection film according to Example 1 are shown. First, Table 1 shows the characteristics of the antireflection film 100. Table 1 shows the refractive index, optical film thickness, and material of the substrate 110, the first layer 101, the second layer 102, and the third layer 103 with respect to the design center wavelength of 510 nm. In Table 1, the refractive index with respect to the design center wavelength 510 nm of the substrate 110 is n, the refractive index with respect to the design center wavelength 510 nm of the first layer 101 is n ₁ , the optical film thickness is n ₁ d ₁ , and the design center of the second layer 102. The refractive index for a wavelength of 510 nm is n ₂ , the optical film thickness is n ₂ d ₂ , the refractive index for the design center wavelength 510 nm of the third layer 103 is n ₃ , the optical film thickness is n ₃ d ₃ , and the design center wavelength is 510 nm. Indicated by λ ₀ . In addition, if each numerical value shown in Table 1 is a value close to the numerical value, the effect expected in Example 1 can be obtained.

  FIG. 2 is a graph showing characteristics of the antireflection film according to Example 1. This graph is shown in Table 1 on a substrate 110 made of a glass or ceramic material having a refractive index n with respect to a design center wavelength of 510 nm of 2.0, 2.1, 2.2, 2.3, and 2.4, respectively. The characteristics when the antireflection film 100 having the characteristics shown in FIG. From this graph, the antireflection film 100 formed on the substrate 110 having a refractive index n of 2.00 to 2.40 has a reflectance of about 0.5% for light in the visible light region (wavelength 400 to 700 nm). It turns out that it can suppress below. In particular, when the antireflection film 100 is formed on the substrate 110 having a refractive index of 2.4, the reflectance with respect to light in the visible light region can be reduced to approximately 0.3% or less, and an excellent antireflection effect can be obtained. . Further, it can be seen that the antireflection film 100 can suppress the reflectance with respect to light in the near-infrared region (wavelength 800 to 1000 nm) to about 1.5 to about 4.0 percent or less.

  As described above, according to the antireflection film according to Example 1, an excellent antireflection effect can be obtained for incident light from the visible light region to the near infrared region.

(Example 2)
Next, a detailed configuration of the antireflection film according to Example 2 will be described. The antireflection film 100 of the second embodiment also includes a first layer 101 stacked on the substrate 110, a second layer 102 stacked on the first layer 101, and a third layer stacked on the second layer 102. 3 layers.

The substrate 110 is formed of a ceramic having a refractive index of 2.20 at a design center wavelength of 510 nm. The first layer 101 is formed of Al ₂ O ₃ so as to be lower than the refractive index of the substrate 110 (the refractive index at the design center wavelength 510 nm is 1.65). Then, the optical film thickness of the first layer 101 is set to 0.039λ ₀ (λ ₀ is the design center wavelength 510 nm). The second layer 102 is formed of a mixed material of ZrO ₂ and TiO ₂ so as to be higher than the refractive index of the first layer 101 or the third layer 103 (the refractive index at the design center wavelength 510 nm is 2.10). The mixing ratio of ZrO ₂ and TiO _{2 at} this time is 6: 1. Then, the optical thickness of the second layer 102 is set to 0.058λ _0. The third layer 103 is formed of MgF ₂ so that the refractive index is the lowest among the layers (the refractive index at the design center wavelength of 510 nm is 1.38). Then, the optical thickness of the third layer 103 is set to 0.192λ _0.

Next, characteristics of the antireflection film according to Example 2 are shown. First, Table 2 shows the characteristics of the antireflection film 100. Table 2 shows the refractive index, optical film thickness, and material of the substrate 110, the first layer 101, the second layer 102, and the third layer 103 with respect to the design center wavelength of 510 nm. Further, the design center wavelength 510 nm is indicated by λ ₀ . In addition, if each numerical value shown in Table 2 is a value close to the numerical value, the effect expected in Example 2 can be obtained.

  FIG. 3 is a graph showing characteristics of the antireflection film according to Example 2. This graph shows the characteristics when the antireflection film 100 having the characteristics shown in Table 2 is formed on the substrate 110 made of ceramics having a refractive index n of 2.20 with respect to the design center wavelength of 510 nm. is there. From this graph, the antireflection film 100 formed on the substrate 110 having a refractive index n of 2.20 has a reflectance of 1% or less, particularly a wavelength of 420 to 660 nm, with respect to light in the visible light region (wavelength 400 to 700 nm). It can be seen that the reflectance with respect to the light can be suppressed to 0.3% or less. Further, it can be seen that the antireflection film 100 can suppress the reflectance with respect to light in the near-infrared region (wavelength 800 to 1000 nm) to about 1.5 to about 4.0 percent or less.

  As described above, according to the antireflection film according to Example 2, an excellent antireflection effect can be obtained for incident light from the visible light region to the near infrared region.

  As described above, according to the antireflection film of this example, when formed on a substrate made of a high refractive index material having a refractive index of 2.00 to 2.40 at a design center wavelength of 510 nm, visible light is visible. An excellent antireflection effect can be obtained for incident light from the region to the near infrared region. In addition, this anti-reflection film uses only four kinds of low-cost materials and is composed of only three layers, so that not only the material cost is reduced, but also the manufacturing process is simplified and the cost is reduced. be able to.

  As described above, the antireflection film and the manufacturing method thereof according to the present invention can obtain an excellent antireflection effect for incident light from the visible light region to the near infrared region, and in particular, a high refractive index material. It is suitable for forming on a substrate made of

It is sectional drawing which shows the structure of the antireflection film concerning embodiment of this invention. 3 is a graph showing characteristics of an antireflection film according to Example 1. 6 is a graph showing characteristics of an antireflection film according to Example 2.

Explanation of symbols

100 Antireflection film 101 1st layer 102 2nd layer 103 3rd layer 110 Substrate

Claims (7)

The refractive index at the design center wavelength is about 1.65, which is lower than the refractive index of the substrate, laminated on a substrate made of a high refractive index material having a refractive index at the design center wavelength of about 2.0 to about 2.4. A first layer,
A second layer laminated on the first layer and having a refractive index at a design center wavelength of about 2.10 which is substantially equal to a refractive index of the substrate;
A third layer laminated on the second layer and having a refractive index at a design center wavelength of about 1.38 lower than that of the substrate, the first layer, and the second layer;
An antireflection film comprising: When the design center wavelength is λ ₀ ,
The optical thickness of the first layer is about 0.027λ ₀ to about 0.055λ ₀ , and the optical thickness of the second layer is about 0.041λ ₀ to about 0.077λ _0. 2. The antireflection film according to claim 1, wherein the optical film thickness is set to be about 0.189λ ₀ to about 0.201λ ₀ . The optical film thickness is about 0.027λ ₀ to about 0.055λ ₀ (λ ₀₎ laminated on a substrate made of a high refractive index material having a refractive index at the design center wavelength of about 2.0 to about 2.4. Is a design center wavelength), and a first layer made of a medium refractive index material whose refractive index at the design center wavelength is lower than the refractive index of the substrate;
A high refractive index material having an optical film thickness of about 0.041λ ₀ to about 0.077λ ₀ laminated on the first layer and having a refractive index at the design center wavelength substantially equal to the refractive index of the substrate. A second layer,
The optical film thickness laminated on the second layer is about 0.189λ ₀ to about 0.201λ ₀ , and the refractive index at the design center wavelength is the refraction of the substrate, the first layer, and the second layer. A third layer made of a low refractive index material lower than the refractive index;
An antireflection film comprising:   The refractive index at the design center wavelength of the first layer is about 1.65, the refractive index at the design center wavelength of the second layer is about 2.10, and the refractive index at the design center wavelength of the third layer is about 1.38. The antireflection film according to claim 3, wherein The substrate is made of a high refractive index glass material or a ceramic material, the first layer is made of Al ₂ O ₃ (aluminum oxide), and the second layer is made of ZrO ₂ (zirconium oxide) and TiO ₂ (titanium oxide). The antireflection film according to claim 1, wherein the antireflection film is made of a mixture mixed at a ratio of 6: 1, and the third layer is made of MgF ₂ (magnesium fluoride). . The optical film thickness is 0.039λ ₀ (λ ₀ is the design center wavelength) laminated on a substrate made of a high refractive index ceramic material having a refractive index of 2.20 at the design center wavelength. A first layer made of Al ₂ O ₃ (aluminum oxide) having a refractive index of 1.65 lower than the refractive index of the substrate;
ZrO ₂ (zirconium oxide) laminated on the first layer and having an optical film thickness of 0.058λ ₀ and a refractive index at the design center wavelength of 2.10, which is substantially the same as the refractive index of the substrate. And a second layer made of a material in which TiO ₂ (titanium oxide) is mixed at a ratio of 6: 1,
The optical film thickness laminated on the second layer is 0.192λ ₀ and the refractive index at the design center wavelength is 1.38, which is lower than the refractive indexes of the substrate, the first layer, and the second layer. A third layer of MgF ₂ (magnesium fluoride);
An antireflection film comprising: On a substrate made of a high refractive index material having a refractive index at a design center wavelength of about 2.0 to about 2.4, a first refractive index at a design center wavelength is about 1.65, which is lower than the refractive index of the substrate. A first layer stacking step of stacking layers;
A second layer laminating step of laminating a second layer having a refractive index at a design center wavelength of about 2.10 equivalent to the refractive index of the substrate on the first layer;
A third layer stacking step of stacking a third layer having a refractive index at a design center wavelength of about 1.38 lower than that of the substrate, the first layer, and the second layer on the second layer;
An antireflection film manufacturing method comprising:

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