JP2016057471A - Anti-reflection film and optical component having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anti-reflection film that exhibits a good anti-reflection effect while minimizing an increase in manufacturing time, manufacturing cost, and film thickness, and to provide an optical component having the same.SOLUTION: An anti-reflection film 30 comprises first through fifth layers 40-80 in order from a substrate 20 side in a stack, the first layer 40 having a refractive index of 1.30-1.75 and physical thickness of 0-220 nm, the second layer 50 having a refractive index of 1.60-2.50 and physical thickness of 4-120 nm, the third layer 60 having a refractive index of 1.30-1.75 and physical thickness of 4-170 nm, the fourth layer 70 having a refractive index of 1.90-2.50 and physical thickness of 10-160 nm, and the fifth layer 80 having a refractive index of 1.30-1.50 and physical thickness of 80-120 nm.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an antireflection film applied to an optical component such as a lens mounted on an optical device such as a camera, a video, or a DVD, and an optical component having the same.

  Conventionally, various coatings have been applied to optical components depending on the application. Among them, the antireflection film is the most common coating, and is often used to reduce the surface reflectance of optical fixtures.

  That is, taking optical glass BK7 (refractive index of 1.52), which is generally used as a substrate for optical components, as an example, there is a reflection loss of about 4% on one side and about 8% on both sides with respect to incident light, In the optical system, this reflection causes various problems such as light loss, noise, and reflection of external light. Therefore, an antireflection film is generally used to solve the problem caused by such reflection.

  Usually, such an antireflection film is formed in a 1 to 4 layer structure, that is, a single layer film is formed on a substrate, or a high refractive index material and a low refractive index material are alternately formed on a substrate in two layers. It is formed by laminating four layers, thereby obtaining an antireflection effect by utilizing the light interference effect of the thin film.

Here, an example of the configuration of a commonly used four-layer antireflection film will be shown.
Substrate: BK7 (refractive index 1.52), first layer: (ZrO ₂ , refractive index 2.05, physical film thickness 28.1 nm), second layer: (SiO ₂ , refractive index 1.46, physical film thickness) 20.0 nm), third layer: (ZrO ₂ , refractive index 2.05, physical film thickness 72.3 nm), fourth layer: (SiO ₂ , refractive index 1.46, physical film thickness 90.0 nm).

  However, the antireflection film having the four-layer structure as described above cannot obtain a sufficiently low reflectance of about 0.5% or less in the wavelength range of 430 to 650 nm, and various refractions can be obtained. There is a drawback that it is difficult to obtain a desired reflectance with respect to a substrate having a refractive index.

  In order to solve such problems, an antireflection treatment using an antireflection film composed of more layers is effective. As an example of such an antireflection film, antireflection processes described in Patent Documents 1 to 3 are available. Membranes are known.

JP 05-002101 A JP 59-208501 A JP 2011-141339 A

Patent Documents 1 and 2 disclose five layers of antireflection films, and particularly describe that the reflectance in the range of 400 to 450 nm can be reduced. However, there is a problem that a sufficiently low reflectance cannot be obtained in a wider visible region of 430 to 650 nm. Although the MgF ₂ film is used for the first layer, the fluoride film has low plasma resistance, hinders assist film formation on the fluoride film, and use for other than the final layer deteriorates mechanical properties. Cause.

Further, Patent Document 3 discloses 11 layers of antireflection films with alternating layers of SiO ₂ / TiO ₂ , but since the number of layers is as large as 11 layers and the total film thickness is as thick as 500 to 630 nm, There is a problem in that the film formation time is long in manufacturing and a great manufacturing cost is required.

  Accordingly, the present invention solves these problems and provides an antireflection film that exhibits a good antireflection effect while suppressing an increase in manufacturing time, manufacturing cost, and total film thickness, and an optical component having the same. It is intended to do.

The antireflection film of the present invention is an antireflection film formed by laminating a first layer to a fifth layer in order from the substrate side. The first layer has a refractive index of 1.30 to 1.75, a physical film thickness. The second layer has a refractive index of 1.60 to 2.50 and a physical film thickness of 4 to 120 nm, and the third layer has a refractive index of 1.30 to 1.75 and physical. The film thickness is 4 to 170 nm, the fourth layer has a refractive index of 1.90 to 2.50, the physical film thickness is 10 to 160 nm, and the fifth layer has a refractive index of 1.30 to 1.50. The physical film thickness of 80 to 120 nm solves the above-mentioned problem.
Moreover, the optical component of the present invention solves the above problems by including the antireflection film and a substrate on which the antireflection film is formed.

  According to the present invention, the first layer has a refractive index of 1.30 to 1.75, a physical film thickness of 0 to 220 nm, and the second layer has a refractive index of 1.60 to 2.50 and a physical film thickness: 4 to 120 nm, 3rd layer, refractive index: 1.30 to 1.75, physical film thickness: 4 to 170 nm, 4th layer, refractive index: 1.90 to 2.50, physical film thickness: 10 By forming the fifth layer at 160 nm with a refractive index of 1.30 to 1.50 and a physical film thickness of 80 to 120 nm, the number of layers can be reduced, and the manufacturing time, manufacturing cost, and total film thickness can be increased. While suppressing, a favorable antireflection effect can be exhibited, and in particular, the spectral reflectance in the wavelength range of 430 to 650 nm can be suppressed to 0.1% or less.

Sectional drawing which shows the structural example of the optical component of this invention. The table | surface and graph which show the analysis result of 1st Example. The table | surface and graph which show the analysis result of 2nd Example. The table | surface and graph which show the analysis result of 3rd Example. The table | surface and graph which show the analysis result of 4th Example. The table | surface and graph which show the analysis result of 5th Example. The table | surface and graph which show the analysis result of 6th Example. The table | surface and graph which show the analysis result of 7th Example. The table | surface and graph which show the measurement result of 7th Example. The table | surface and graph which show the analysis result of a comparative example.

  The optical component of the present invention will be described below with reference to the accompanying drawings.

  The optical component 10 is configured as a lens or the like mounted on an optical device such as a camera, video, or DVD, and includes a substrate 20 and an antireflection film 30 formed on one surface of the substrate 20 as shown in FIG. Has been.

The substrate 20 has a refractive index of 1.3 to 2.4. Examples of the material of the substrate 20 include BK7 (refractive index 1.52), synthetic quartz glass (refractive index 1). .46), sapphire glass (refractive index 1.77), LiNbO ₃ (refractive index 2.2), and the like.

  As shown in FIG. 1, the antireflection film 30 is formed by one or more methods selected from the group consisting of vacuum deposition, ion-assisted deposition (IAD), ion plating deposition (IP), and CVD. The first layer 40 to the fifth layer 80 are stacked in order from the substrate 20 side.

The first layer 40 is formed to have a refractive index of 1.30 to 1.75 and a physical film thickness of 0 to 220 nm. The material of the first layer 40 is SiO ₂ , Al ₂ O ₃ , SiO, MgO or the following mixed material is mentioned.

Here, the “mixed material” used in this specification refers to SiO ₂ , Al ₂ O ₃ , SiO, MgO, Y ₂ O ₃ , SnO ₂ , Ta ₂ O ₅ , HfO ₂ , ZrO ₂ , CeO ₂ , Selected from WO ₃ , TiO ₂ , Nb ₂ O ₅ , La ₂ O ₃ , ZnO, Na ₅ Al ₃ F ₁₄ , Na ₃ AlF ₆ , AlF ₃ , MgF ₂ , CaF ₂ , BaF ₂ , and YF ₃ It means a material in which at least two kinds are mixed.

The second layer 50 is formed so as to have a refractive index of 1.60 to 2.50 and a physical film thickness of 4 to 120 nm. The material of the second layer 50 includes Al ₂ O ₃ , SiO, and Y ₂ O. _{3, SnO 2, Ta 2 O} 5, HfO 2, ZrO 2, CeO 2, WO 3, TiO 2, Nb 2 O 5, La 2 O 3, ZnO , or the mixed materials.

The third layer 60 is formed so as to have a refractive index of 1.30 to 1.75 and a physical film thickness of 4 to 170 nm. Materials of the third layer 60 include SiO ₂ , Al ₂ O ₃ , SiO, MgO or the mixed material can be given.

The fourth layer 70 is formed so as to have a refractive index of 1.90 to 2.50 and a physical film thickness of 10 to 160 nm. The material of the fourth layer 70 is SnO ₂ , Ta ₂ O ₅ , HfO _2. , ZrO ₂ , CeO ₂ , WO ₃ , TiO ₂ , Nb ₂ O ₅ , La ₂ O ₃ , ZnO, or the mixed material.

The fifth layer 80 is formed so as to have a refractive index of 1.30 to 1.50 and a physical film thickness of 80 to 120 nm. The material of the fifth layer 80 is Na ₅ Al ₃ F ₁₄ , Na ₃ AlF. _{6, AlF 3, MgF 2,} CaF 2, SiO 2, BaF 2, YF 3, or the mixed materials.

  In the example shown in FIG. 1, no layer is formed on the surface of the antireflection film 30, but Cytop (registered trademark, manufactured by Asahi Glass Co., Ltd.), parylene, poly A layer made of paraxylylene, Teflon (registered trademark), polyethylene, diamond-like carbon, or the like may be further formed.

  The optical component 10 thus obtained has an antireflection effect with a spectral reflectance of 0.1% or less in the wavelength region of 430 to 650 nm.

  Below, a plurality of examples of the present invention are described based on a drawing. In each of the following examples, the material design of the substrate 20 and each layer 40 to 80 is variously changed and analyzed, so that the spectral reflectance is 0.1% or less in the wavelength region of 430 to 650 nm. The physical film thickness of each layer 40-80 is optimized.

[Example 1]
First, a first embodiment of the present invention will be described below with reference to FIG.

In the first embodiment, the substrate 20 is designed using BK7 (refractive index 1.52) as a material, the first layer 40 is made of Al ₂ O ₃ (refractive index 1.65), and the second layer 50 is made of a material. A mixture of La ₂ O ₃ and TiO ₂ (refractive index 2.0) is used, the material of the third layer 60 is Al ₂ O ₃ (refractive index 1.65), and the material of the fourth layer 70 is Ta ₂ O ₅ ( The material of the fifth layer 80 was designed as MgF ₂ (refractive index 1.38).

  In the optical component 10 of the first embodiment, the physical thickness of the first layer 40 is designed to be 74.7 nm, the physical thickness of the second layer 50 is designed to be 114.8 nm, When the physical film thickness is designed at 132.2 nm, the physical film thickness of the fourth layer 70 is designed at 110.2 nm, and the physical film thickness of the fifth layer 80 is designed at 91 nm, in the wavelength range of 430 to 650 nm It was confirmed that the spectral reflectance showed a value of 0.1% or less.

[Example 2]
Next, a second embodiment of the present invention will be described below with reference to FIG.

  In the second embodiment, the substrate 20 is designed using synthetic quartz glass (refractive index 1.46) as a material, and the materials of the first layer 40 to the fifth layer 80 are designed in the same manner as in the first embodiment.

  In the optical component 10 of the second embodiment, the physical film thickness of the first layer 40 is designed to be 72 nm, the physical film thickness of the second layer 50 is designed to be 111.6 nm, and the physical film of the third layer 60 is designed. When the thickness is designed to be 138.1 nm, the physical thickness of the fourth layer 70 is designed to be 111 nm, and the physical thickness of the fifth layer 80 is designed to be 90 nm, the spectral reflectance is measured in the wavelength range of 430 to 650 nm. Was confirmed to show a value of 0.1% or less.

[Example 3]
Next, a third embodiment of the present invention will be described below with reference to FIG.

  In the third embodiment, the substrate 20 is designed using sapphire glass (refractive index 1.77) as a material, and the materials of the first layer 40 to the fifth layer 80 are designed in the same manner as in the first embodiment.

  In the optical component 10 of the third embodiment, the physical thickness of the first layer 40 is designed at 152 nm, the physical thickness of the second layer 50 is designed at 115 nm, and the physical thickness of the third layer 60 is set. In the wavelength range of 430 to 650 nm, the fourth layer 70 is designed to have a physical film thickness of 110.7 nm, and the fifth layer 80 is designed to have a physical film thickness of 91.7 nm. It was confirmed that the reflectance shows a value of 0.1% or less.

[Example 4]
Next, a fourth embodiment of the present invention will be described below with reference to FIG.

In the fourth embodiment, the substrate 20 is designed using a LiNbO ₃ crystal (refractive index of 2.2) as a material, and the materials of the first layer 40 to the fifth layer 80 are designed in the same manner as in the first embodiment.

  In the optical component 10 of the fourth embodiment, the physical thickness of the first layer 40 is designed to be 0 nm, the physical thickness of the second layer 50 is designed to be 74 nm, and the physical thickness of the third layer 60 is In the case where the fourth layer 70 is designed to have a physical film thickness of 121.5 nm and the fifth layer 80 is designed to have a physical film thickness of 95.8 nm, the spectral reflectance is measured in the wavelength range of 430 to 650 nm. Was confirmed to show a value of 0.1% or less.

[Example 5]
Next, a fifth embodiment of the present invention will be described below with reference to FIG.

In the fifth embodiment, the substrate 20 is designed using BK7 (refractive index 1.52) as a material, the material of the first layer 40 is SiO ₂ (refractive index 1.46), and the material of the second layer 50 is Al _2. O ₃ (refractive index 1.65), the material of the third layer 60 is SiO ₂ (refractive index 1.46), the material of the fourth layer 70 is Ta ₂ O ₅ (refractive index 2.2), The material of the five layers 80 was designed as MgF ₂ (refractive index 1.38).

  In the optical component 10 of the fifth embodiment, the physical thickness of the first layer 40 is designed to be 91 nm, the physical thickness of the second layer 50 is designed to be 48.2 nm, and the physical film of the third layer 60 is designed. When the thickness is designed to be 23.3 nm, the physical thickness of the fourth layer 70 is designed to be 121.5 nm, and the physical thickness of the fifth layer 80 is designed to be 94 nm, in the wavelength region of 430 to 650 nm, It was confirmed that the reflectance shows a value of 0.1% or less.

[Example 6]
Next, a sixth embodiment of the present invention will be described below with reference to FIG.

In the fifth embodiment, the substrate 20 is designed using BK7 (refractive index 1.52) as a material, the material of the first layer 40 is SiO ₂ (refractive index 1.46), and the material of the second layer 50 is TiO _2. (Refractive index 2.45), the material of the third layer 60 is SiO ₂ (refractive index 1.46), the material of the fourth layer 70 is TiO ₂ (refractive index 2.45), The material was designed as SiO ₂ (refractive index 1.46).

  In the optical component 10 of the sixth embodiment, the physical thickness of the first layer 40 is designed to be 30.5 nm, the physical thickness of the second layer 50 is designed to be 12.4 nm, When the physical film thickness is designed at 38.4 nm, the physical film thickness of the fourth layer 70 is designed at 113 nm, and the physical film thickness of the fifth layer 80 is designed at 89.7 nm, in the wavelength range of 430 to 650 nm It was confirmed that the spectral reflectance showed a value of 0.1% or less.

[Example 7]
Next, a seventh embodiment of the present invention will be described below with reference to FIG.

In the seventh embodiment, the substrate 20 is designed using BK7 (refractive index 1.52) as a material, the material of the first layer 40 is SiO ₂ (refractive index 1.46), and the material of the second layer 50 is Ta _2. O ₅ (refractive index 2.2), the material of the third layer 60 is SiO ₂ (refractive index 1.46), the material of the fourth layer 70 is Ta ₂ O ₅ (refractive index 2.2), The material of the five layers 80 was designed as MgF ₂ (refractive index 1.38).

  In the optical component 10 of the seventh embodiment, the physical thickness of the first layer 40 is designed to be 80.2 nm, the physical thickness of the second layer 50 is designed to be 11 nm, and the physical film of the third layer 60 is designed. In the case where the thickness is designed to be 46.5 nm, the physical thickness of the fourth layer 70 is designed to be 124.8 nm, and the physical thickness of the fifth layer 80 is designed to be 95 nm, in the wavelength region of 430 to 650 nm, It was confirmed that the reflectance shows a value of 0.1% or less.

  In the seventh embodiment described above, the optical component 10 was actually formed by the vacuum deposition method under the above conditions, and the spectral reflectance was measured. As can be seen from the graph of FIG. 9 showing this measurement result, there is almost no difference between the analysis result and the measurement result, and the spectral reflectance is 0.1% or less in the wavelength region of 430 to 650 nm. It was confirmed that

[Comparative example]
Next, a comparative example of the present invention will be described below based on FIG.

In this comparative example, a general antireflection film 30 having a four-layer structure, that is, the substrate 20 is designed using BK7 (refractive index of 1.52) as a material, and the material of the first layer 40 is a mixture of TiO ₂ and ZrO ₂ . (Refractive index 2.05), the material of the second layer 50 is SiO ₂ (refractive index 1.46), the material of the third layer 60 is a mixture of TiO ₂ and ZrO ₂ (refractive index 2.05), By analyzing the antireflection film 30 in the case where the material of the fourth layer 70 is SiO ₂ (refractive index 1.46), each layer 40 to 40 so that the spectral reflectance in the wavelength region of 430 to 650 nm is lowered. The physical film thickness of 70 is optimized.

  From the analysis result of this comparative example, it was found that the spectral reflectance could not be suppressed to 0.1% or less in the wavelength range of 430 to 650 nm.

DESCRIPTION OF SYMBOLS 10 ... Optical component 20 ... Board | substrate 30 ... Antireflection film 40 ... 1st layer 50 ... 2nd layer 60 ... 3rd layer 70 ... 4th layer 80 ... 5th layer

Claims (6)

An antireflection film comprising a first layer to a fifth layer laminated in order from the substrate side,
The first layer has a refractive index of 1.30 to 1.75, a physical film thickness of 0 to 220 nm,
The second layer has a refractive index of 1.60 to 2.50 and a physical film thickness of 4 to 120 nm.
The third layer has a refractive index of 1.30 to 1.75 and a physical film thickness of 4 to 170 nm.
The fourth layer has a refractive index of 1.90 to 2.50 and a physical film thickness of 10 to 160 nm.
The fifth layer has a refractive index of 1.30 to 1.50 and a physical film thickness of 80 to 120 nm. _{SiO 2, Al 2 O 3,} SiO, MgO, Y 2 O 3, SnO 2, Ta 2 O 5, HfO 2, ZrO 2, CeO 2, WO 3, TiO 2, Nb 2 O 5, La 2 O 3, When a material in which at least two selected from ZnO, Na ₅ Al ₃ F ₁₄ , Na ₃ AlF ₆ , AlF ₃ , MgF ₂ , CaF ₂ , BaF ₂ , and YF ₃ are mixed is defined as a mixed material,
The first layer and the third layer are made of SiO ₂ , Al ₂ O ₃ , SiO, MgO, or the mixed material,
The second layer is made of Al ₂ O ₃ , SiO, Y ₂ O ₃ , SnO ₂ , Ta ₂ O ₅ , HfO ₂ , ZrO ₂ , CeO ₂ , WO ₃ , TiO ₂ , Nb ₂ O ₅ , La ₂ O _3. , ZnO, or the mixed material,
The fourth layer is made of SnO ₂ , Ta ₂ O ₅ , HfO ₂ , ZrO ₂ , CeO ₂ , WO ₃ , TiO ₂ , Nb ₂ O ₅ , La ₂ O ₃ , ZnO, or the mixed material,
The fifth layer is made of Na ₅ Al ₃ F ₁₄ , Na ₃ AlF ₆ , AlF ₃ , MgF ₂ , CaF ₂ , SiO ₂ , BaF ₂ , YF ₃ , or the mixed material. 2. The antireflection film according to 1.   The antireflection film according to claim 1, wherein the antireflection film has an antireflection effect with a spectral reflectance of 0.1% or less in a wavelength region of 430 to 650 nm.   The first to fifth layers are formed by one or more methods selected from the group consisting of a vacuum deposition method, an ion assist deposition method, an ion plating deposition method, and a CVD method. The antireflection film according to any one of claims 1 to 3.   An optical component comprising the antireflection film according to claim 1 and a substrate on which the antireflection film is formed.   The antireflection film according to claim 5, wherein the refractive index of the substrate is 1.3 to 2.4.

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