JPH05264802A - Multilayered antireflection film - Google Patents

Abstract

PURPOSE:To obtain an excellent antireflection effect for both of S-polarized component and P-polarized component in a wide wavelength range. CONSTITUTION:This multilayered antireflection film 15 is used for light at <=60 deg. incident angle and consists of 11 layers formed on an optical member 20 having 1.50-1.54 refractive index. These layers are successively deposited from the first layer 1 to the tenth layer 10 and the eleventh layer 11. Any one layer of odd number is given refractive index 2.29-2.35, another layer of odd number is given refractive index 2.04-2.06, and four layers of odd numbers is given refractive index 1.37-1.39. Further, any one layer of even number is given refractive index 1.99-2.01, another layer is given refractive index 1.92-1.94, another layer is given refractive index 1.64-1.65, and the remaining two layers are given refractive index 1.47-1.49.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, a camera, a telescope, various optical measuring devices, various OA devices, laser applied devices, various electronic image devices, optical communication devices, optical information processing devices,
The present invention relates to a multilayer antireflection film applied to an optical component that constitutes an optical device such as an optical application manufacturing apparatus.

[0002]

2. Description of the Related Art Cameras, telescopes, laser printers,
Many optical components such as lenses and prisms are used in optical devices such as optical disc devices, laser processing devices such as laser processing devices and measuring devices, and electronic image devices such as video cameras and video projectors. ,
For such an optical component, an antireflection film is generally formed in order to prevent harmful surface reflection. This antireflection film is formed by laminating one or two or more thin films made of an inorganic substance such as TiO ₂ , SiO ₂ , or MgF _{2 on} the surface of an optical component by a vacuum deposition method or the like. (JP-A-62-178901
JP-A-3-246501, JP-A-3-25260
No. 2).

By the way, in an optical system for a laser, many optical components and the like are used, and the structure thereof is complicated, but in recent years, it has been a subject to make them more compact. In designing, the incident angle of the laser light on the optical component becomes large (45 to 6).
0 degree). However, it is generally known that the antireflection film formed on the surface of the optical component has less antireflection effect as the incident angle increases.

A polarization beam splitter is used in the optical system of an optical disk device, for example.
In some cases, it is necessary to prevent reflection of each of the polarized light component and the P polarized light component. In this case, however, conventionally, one multilayer antireflection film is used to prevent reflection of each of the S polarized light component and the P polarized light component. There is nothing to gain, S
A dedicated antireflection film to prevent reflection of polarized components,
It was necessary to separately provide a dedicated antireflection film for preventing the reflection of the P-polarized component. Therefore, the number of layers of the antireflection film to be formed is large, and the antireflection film must be formed in two or more places.
There is a problem that the width of the design is narrowed and the cost is increased.

Further, the antireflection effect of both the S-polarized component and the P-polarized component has wavelength dependence in the antireflection effect. For example, when the wavelength of the incident light deviates from the design wavelength by ± 20 nm or more, the reflectance is When it exceeds 3%, the antireflection effect is insufficient.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to prevent reflection of S-polarized light components and P-polarized light components with a single multilayer antireflection film, and to obtain an excellent antireflection effect over a wide wavelength range. It is to provide an antireflection film.

[0007]

Such an object is achieved by the present invention described below.

That is, according to the present invention, the layers from the first layer to the eleventh layer are provided on the surface of an optical component used at an incident angle of 60 ° or less and having a refractive index of 1.50 to 1.54. A multilayer antireflection film laminated in this order from the side,
The refractive index of any one of the odd-numbered layers is 2.2.
9 to 2.35, the refractive index of any one of the other layers is 2.04 to 2.06, and the refractive index of the remaining four layers is 1.37 to 1.39, respectively. The refractive index of any one of the second layers is 1.99 to 2.01, and the refractive index of any one of the other layers is 1.92 to.
1.94, the refractive index of any one of the other layers is 1.64 to 1.65, and the refractive indexes of the remaining two layers are 1.47 to 1.49, respectively. It is a multi-layer antireflection film.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The multilayer antireflection film of the present invention will be described in detail below with reference to the preferred embodiments shown in the accompanying drawings. Figure 1
[FIG. 3] is a cross-sectional side view showing an enlarged configuration of a multilayer antireflection film of the present invention. As shown in FIG.
Are formed on the surface of the optical component 20.

As the optical component 20, for example, a lens made of various transparent glass materials or plastics (for example, acrylic resin, polycarbonate, polystyrene),
Examples include prisms and optical filters. Further, the surface of the optical component 20 on which the multilayer antireflection film 15 is formed may be a flat surface as shown, or may be a curved surface (spherical surface or aspherical surface).

Such an optical component 20 has an incident angle θ of 60 ° or less, preferably 30 to 30 in a normal use condition.
It is used at 60 °, more preferably 45 to 60 °, and further preferably 50 to 60 °.

The refractive index of the optical component 20 is 1.50.
˜1.54, preferably 1.51 to 1.53. When the refractive index is in such a range, the antireflection effect described later is effectively exhibited.

The multi-layer antireflection film 15 is laminated in order from the front surface side of the optical component 20, the first layer 1, the second layer 2, the third layer 3, the fourth layer 4, the fifth layer 5 and the sixth layer. The sixth layer 7, the seventh layer 8, the eighth layer 8, the ninth layer 9, the tenth layer 10 and the eleventh layer 11 are composed of a total of 11 layers. Among these layers, it is effective for preventing reflection that the two adjacent layers have different refractive indexes.

That is, the odd-numbered layers 1, 3, 5, 7,
The refractive index of any one of 9 and 11 is 2.2.
9 to 2.35, the refractive index of any one of the other layers is from 2.04 to 2.06, and the remaining four layers have refractive indices of 1.37 to 1 respectively. .39, and even layers 2, 4, 6, 8
And the refractive index of any one of 10 is 1.99.
To 2.01 and the refractive index of any other one layer is in the range of 1.92 to 1.94, and the refractive index of any one other layer is 1.64 to 1. And the refractive index of the remaining two layers is 1.
It should be in the range of 47 to 1.49. The refractive index referred to here is a refractive index measured at a wavelength of 550 nm.

By setting the refractive indices of the respective layers 1 to 11 as described above, not only when the incident angle θ is relatively small, but also when the incident angle θ is about 60 °, an excellent antireflection effect, In particular, an excellent antireflection effect is obtained for both the S-polarized component and the P-polarized component, and the effect is obtained in a wide wavelength range.

Examples of the constituent materials of the layers 1 to 11 are as follows. Examples of those having a refractive index in the range of 2.29 to 2.35 include titanium oxides such as TiO ₂ , cerium oxides such as CeO ₂ , and compositions containing these as the main components.

Examples of those having a refractive index in the range of 2.04 to 2.06 include tantalum oxides such as TaO ₂ and Ta ₂ O ₅ , praseodymium oxides such as Pr ₆ O ₁₁ and CeO ₂ . A mixture of such a cerium oxide and a yttrium oxide such as Y ₂ O ₃ (the preferred mixing ratio is
Cerium oxide (40% by weight, yttrium oxide (60% by weight)) or a composition containing these as main components.

Examples of materials having a refractive index in the range of 1.99 to 2.01 include indium oxides such as In ₂ O ₃ , antimony oxides such as Sb ₂ O ₃ , TaO ₂ ,
A mixture of tantalum oxide such as Ta ₂ O ₅ and yttrium oxide such as Y ₂ O ₃ (preferable mixing ratio is 70% by weight of tantalum oxide and 30% by weight of yttrium oxide), or a main component thereof. And a composition of

Examples of those having a refractive index in the range of 1.92 to 1.94 include ytterbium oxides such as Yb ₂ O ₃ , silicon oxides such as SiO ₂ and zirconium oxides such as ZrO ₂ . (A preferable mixing ratio is 30% by weight of silicon oxide and 70% of zirconium oxide).
% By weight), or a composition containing them as a main component.

Examples of those having a refractive index in the range of 1.64 to 1.65 include aluminum oxides such as Al ₂ O ₃ and cerium fluorides such as CeF ₃ or compositions containing these as the main components. Is mentioned.

Examples of those having a refractive index in the range of 1.47 to 1.49 include, for example, silicon oxides such as SiO ₂ and M
a mixture of a fluorine compound such as gF ₂ and an aluminum oxide such as Al ₂ O ₃ (a preferable mixing ratio is 60% by weight of the fluorine compound and 40% by weight of the aluminum oxide),
Alternatively, a composition containing them as a main component may be used.

Examples of those having a refractive index in the range of 1.37 to 1.39 include fluorine compounds such as MgF ₂ and CaF ₂ , or compositions containing these as the main components.

By constituting each layer with the above materials, the multilayer antireflection film 15 is less deteriorated and has excellent durability. Further, the adhesion of the film on the boundary surface between the layers 1 to 11 and the surface of the optical component 20 is also good,
No cracks due to internal stress.

In the present invention, the constituent material of each layer is not limited to those exemplified above, and any material having a refractive index within the above range may be used. Also, each layer 1
Although the optical film thicknesses of to 11 are not particularly limited, it is usually preferable that the optical film thickness of each layer be as follows.

That is, the optical film thickness of the layer having a refractive index in the range of 2.04 to 2.06 is preferably about 0.1 to 0.4 times the central wavelength of the wavelength region in which reflection is desired to be prevented. It is more preferably about 0.15 to 0.35 times, further preferably about 0.17 to 0.33 times. Further, the optical film thickness of the other layers is preferably about 0.1 to 0.4 times, more preferably about 0.15 to 0.35 times the central wavelength of the wavelength region in which reflection is desired to be prevented. More preferably, it is about 0.20 to 0.30 times.

In the present invention, the first layer 1 to the eleventh layer 1
Each of the layers up to 1 has its own optical characteristics, and can be recognized as one unit constituting the multilayer antireflection film. Therefore, each layer 1-11
Any one of the layers can be replaced not only with a physically one layer as shown, but also with a plurality of layers equivalent thereto.

Such replacement can be carried out by the equivalent film method or the composite method (reference: “Optical thin film” P154-158,
(Published on October 10, 1986 by Kyoritsu Publishing Co., Ltd.) and the like, and replacement by the equivalent membrane method is particularly preferable. Hereinafter, an example in the case of performing replacement by the equivalent film method will be described.

For example, the fourth layer can be replaced with three layers, a 4a layer, a 4b layer and a 4c layer. In this case, the 4a layer and the 4c layer are composed of substantially the same material, and are different from the constituent material of the intermediate 4b layer. And the laminated body of the 4a layer, the 4b layer, and the 4c layer is equivalent to the 4th layer regarding the refractive index and the optical film thickness. Needless to say, such replacement can be performed in layers other than the fourth layer.

When such replacement is performed, the number of layers of the multilayer antireflection film is increased, but there are the following advantages. That is, for example, the constituent material of the layer to be replaced (eg, the fourth layer) is rare or unsuitable for film formation, or compatible with the adjacent layer (eg, the third layer or the fifth layer). In the case of low properties (for example, low adhesion or high stress accumulation), by replacing it with an equivalent laminate composed of layers of different materials, without changing the optical characteristics, Such a problem can be improved.

The formation of each of the layers 1 to 11 (including the replaced layer) in the multilayer antireflection film 15 of the present invention is usually performed.
It is carried out by a vapor phase film forming method such as vacuum deposition, sputtering and ion plating, and the above film composition and film thickness can be obtained by setting film forming conditions.

The multilayer antireflection film 15 as described above exhibits a particularly excellent antireflection effect with respect to incident light having a wavelength of 800 to 860 nm and further having a wavelength of 810 to 850 nm.

[0032]

EXAMPLES Specific examples of the present invention will be described below.

(Example 1) [1] Production of multilayer antireflection film After precision cleaning of an optical glass component (BK7, refractive index: 1.51), the following was performed from the surface side of this optical glass component by vacuum deposition. First layer to first layer composed of materials shown in Table 1
One layer was sequentially formed to obtain a multilayer antireflection film of the present invention. In Table 1, the refractive index (measurement wavelength 550 nm) and film thickness of each layer are also shown.

[0034]

[Table 1]

[2] Measurement of Spectral Characteristics Light having a wavelength of 800 to 860 nm (design wavelength 830 nm) is incident on the multilayer antireflection film at an incident angle of 60 °, and the reflectance of each of the S polarization component and the P polarization component is reflected. Was measured. The results are shown in the graph of FIG.

As shown in this graph, S polarization component, P
With respect to both polarization components, the reflectance is about 2% or less when the deviation from the design wavelength is within ± 30 nm, and the reflectance is about 1% or less within ± 20 nm.

(Example 2) [1] Production of multilayer antireflection film The same optical glass parts as in Example 1 were precision cleaned and then vacuum-evaporated to give the results shown in Table 2 below from the surface side of the optical glass parts. First to eleventh layers made of materials were sequentially formed to obtain a multilayer antireflection film of the present invention. In Table 2, the refractive index (measurement wavelength 550 nm) and film thickness of each layer are also shown.

[0038]

[Table 2]

[2] Measurement of Spectral Characteristics Light having a wavelength of 800 to 860 nm (design wavelength 830 nm) is incident on the multilayer antireflection film at an incident angle of 60 °, and the reflectance of each of the S polarization component and the P polarization component is reflected. Was measured. The result is shown in the graph of FIG.

As shown in this graph, S polarization component, P
With respect to both polarization components, the reflectance is about 2% or less when the deviation from the design wavelength is within ± 30 nm, and the reflectance is about 1% or less within ± 20 nm.

Example 3 An optical glass component similar to that of Example 1 was precision cleaned, and then the surface of the optical glass component No. 1 in Table 1 above was cleaned.
A multilayer antireflection film having a layer structure in which the layers and the fifth layer were exchanged and the second layer and the eighth layer were exchanged was produced.

When the spectral characteristics of this multilayer antireflection film were measured in the same manner as in Example 1, both of the S-polarized component and the P-polarized component achieved low reflectances similar to those in Example 1.

(Example 4) The same optical glass component as in Example 1 was precision cleaned, and then, the surface of the optical glass component No. 1 in Table 1 was applied.
The layer and the third layer were exchanged, the fifth layer and the ninth layer were exchanged, and the fourth layer and the tenth layer were exchanged to produce a multilayer antireflection film.

When the spectral characteristics of this multilayer antireflection film were measured in the same manner as in Example 1, both the S-polarized component and the P-polarized component achieved low reflectances similar to those in Example 1.

(Embodiment 5) With respect to each of Embodiments 1, 2, 3 and 4, the same measurement was carried out except that the incident angle was changed to 45 °. The reflectance of the component was significantly reduced. Of these, the results for Example 1 are shown in the graph of FIG.

As shown in this graph, S polarization component, P
For both polarization components, the reflectance is less than 0.5% when the deviation from the design wavelength is within ± 30 nm, and the reflectance is 0.1% when within ± 20 nm.
The following was achieved, and even lower reflectance was obtained compared to the results of Example 1 above. As a result, the effective wavelength range can be made wider.

[0047]

As described above, according to the multilayer antireflection film of the present invention, not only when the incident angle θ is relatively small, but also when the incident angle is about 60 °, excellent antireflection is achieved. As a result, an excellent antireflection effect is obtained for both the S-polarized component and the P-polarized component.

Moreover, the antireflection of the S-polarized component and the P-polarized component can be achieved by one multilayer antireflection film. Further, the excellent antireflection effect can be obtained over a wide wavelength range.

Because of this, the range of design of optical equipment is widened. That is, for example, in the design of the optical path,
The incident angle on the optical component can be set to about 60 ° without considering the loss due to reflection, and as a result, the configuration of the device can be simplified, downsized, and the accuracy can be improved.
Moreover, the multilayer antireflection film of the present invention is also excellent in durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view showing an enlarged configuration of a multilayer antireflection film of the present invention.

FIG. 2 is a graph showing spectral characteristics in Example 1 of the present invention.

FIG. 3 is a graph showing spectral characteristics in Example 2 of the present invention.

FIG. 4 is a graph showing spectral characteristics in Example 5 of the present invention.

[Explanation of symbols]

 1 1st layer 2 2nd layer 3 3rd layer 4 4th layer 5 5th layer 6 6th layer 7 7th layer 8 8th layer 9 9th layer 10 10th layer 11 11th layer 15 Multilayer antireflection film 20 Optical components

Claims (1)

[Claims] 1. A surface of an optical component having an incident angle of 60 ° or less and having a refractive index of 1.50 to 1.54 has a first surface.
A multilayer antireflection film comprising layers 11 to 11 stacked in this order from the front surface side, wherein any one of the odd-numbered layers has a refractive index of 2.2.
9 to 2.35, the refractive index of any one of the other layers is 2.04 to 2.06, and the refractive indices of the remaining four layers are 1.37 to 1.39, respectively. The refractive index of any one of the th layer is 1.9.
9 to 2.01, the refractive index of any one other layer is 1.92 to 1.94, the refractive index of any one other layer is 1.64 to 1.65, A multilayer antireflection film, wherein the refractive indexes of the remaining two layers are 1.47 to 1.49, respectively.