JPH05215915A - Multilayer reflection increase film - Google Patents

Abstract

PURPOSE:To obtain a high reflection index with regard to both of an S polarization component and a P polarization component by a small number of layers, and also, to obtain a no-phase difference state of the S polarization component and the P polarization component of a reflected light extending over a wide wavelength area. CONSTITUTION:The multilayer reflection increase film 19 is constituted by laminating even number layers in 10-18 on the surface of optical parts 20 used at 30-60 deg. incident angle. An odd number-th layer counted from the surface side of the optical parts 20 is constituted of a material mainly composed of at least one compound selected out of a group consisting of TiO2, CeO2, ZnS and Bi2O3, respectively. Also, an even number-th layer counted from the surface side of the optical parts 20 is constituted of a material mainly composed of at least one compound selected out of a group consisting of MgF2 and SiO2.

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 reflection increasing 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 For example, many optical parts such as lenses and prisms are used in laser application equipment such as laser printers, optical disk devices, laser processing devices and measuring devices. On the other hand, in order to reduce the loss of light as much as possible when changing the optical path, a reflection increasing film is formed.
This reflection-increasing film is formed by laminating a plurality of thin films made of an inorganic material such as TiO ₂ , SiO ₂ , or MgF _{2 on} the surface of an optical component by a vacuum vapor deposition method or the like.

This multilayer reflection increasing film has a high reflectance for both the S-polarized component and the P-polarized component, that is, almost 100%.
It is said that obtaining a reflectance close to
For that purpose, it is known that it is effective to increase the number of layers to be laminated. Therefore, in the conventional multilayer reflection increasing film, 20 layers or more are laminated.

However, on the other hand, if the number of layers to be laminated increases, the number of manufacturing steps of the multilayer reflection increasing film increases accordingly, the manufacturing labor and cost increase, and the risk of layer peeling increases, resulting in durability. There is a drawback that the property is lowered. Furthermore, there is a drawback that the risk of cracks due to the stress of each layer increases.

Further, in the optical system for laser, not only a high reflectance is obtained as the performance required for the multilayer reflection increasing film, but also the phase difference between the S-polarized component and the P-polarized component is substantially contained in the reflected light. That does not exist (hereinafter referred to as no phase difference),
In other words, it is important that the light is linearly polarized light. That is, if there is a phase difference between the S-polarized component and the P-polarized component, the spot diameter of the laser beam cannot be reduced and S
This is because the accuracy such as the / N ratio decreases.

Further, in general, the phase difference between the S-polarized light component and the P-polarized light component has wavelength dependency, but the above-mentioned non-phase difference state must be obtained over a wide wavelength range. That is, the wavelength to be used may change due to the specification width of the laser light source itself, changes in the environment, etc., but no phase difference is maintained against such changes and a high level of accuracy is stable. This is because it is preferable to obtain

Regarding such non-phase difference and its wavelength dependence, none of the conventional multilayer reflection increasing films can achieve satisfactory performance. In particular, there is no phase difference at the design wavelength. The phase difference between the S-polarized light component and the P-polarized light component of the reflected light is 5 ° when separated from the design wavelength by ± 30 nm or more.
It was in a state of exceeding.

[0008]

The object of the present invention is to obtain a high reflectance for both the S-polarized light component and the P-polarized light component with a small number of layers, and to provide an inconsistency between the S-polarized light component and the P-polarized light component over a wide wavelength range. An object of the present invention is to provide a multilayer reflection increasing film that can obtain a phase difference state.

[0009]

Such objects are achieved by the present invention described in (1) and (2) below.

(1) A multilayer reflection increasing film formed by laminating an even number layer of 10 to 18 on the surface of an optical component used at an incident angle of 30 to 60 °, counting from the surface side. The odd layers are TiO ₂ , CeO ₂ , and
ZnS and Bi ₂ O ₃ are composed of a material containing at least one compound selected from the group consisting of ZnS and Bi ₂ O ₃ as a main component.
_2. A multilayer reflection increasing film, which is composed of a material whose main component is at least one compound selected from the group consisting of ₂ and SiO ₂ .

(2) The multilayer reflection increasing film as described in (1) above, wherein the constituent material of the optical component has a refractive index of 1.50 to 1.54.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The multilayer reflection increasing film of the present invention will be described below in detail with reference to the preferred embodiments shown in the accompanying drawings.

FIG. 1 is an enlarged sectional side view showing an example of the structure of the multilayer reflection increasing film of the present invention. As shown in the figure,
The multilayer reflection increasing film 19 is 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. The surface of the optical component 20 on which the multilayer reflection increasing film 19 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 30 to 60 °, preferably 35, in a normal use condition.
It is used at about -50 °, more preferably at about 40-47 °. When the incident angle θ is less than 30 °, the reflectance tends to decrease, and when the incident angle θ exceeds 60 °, the phase difference between the S polarized component and the P polarized component becomes large.

The refractive index of the optical component 20 is 1.50.
˜1.54, especially 1.51 to 1.52 is preferred. When the refractive index is in such a range, the effects described below are particularly effectively exhibited.

The number of layers of the multilayer reflection enhancing film of the present invention is 10 to 10.
It is an even number of eighteen. If the number of layers is less than 10, S
Both the polarization component and the P polarization component have reduced reflectance. The reason why the number of layers is even is that if it is odd, a sufficient reflectance cannot be obtained, and the phase difference between the S-polarized component and the P-polarized component becomes large.

The illustrated multilayer reflection enhancing film 19 is used for the optical component 2
The first layer 1, the second layer 2, and the
Third layer 3, fourth layer 4, fifth layer 5, sixth layer 6, seventh layer 7,
8th layer 8, 9th layer 9, 10th layer 10, 11th layer 11, 12th layer 12, 13th layer 13, 14th layer 14, 15th layer 1
5, 16th layer 16, 17th layer 17 and 18th layer 18 in total. Of these layers, it is effective to increase the reflection and retard the phase difference by making the constituent materials of the two adjacent layers different from each other in their refractive indexes.

That is, the odd-numbered layers 1, 3, 5, 7,
9, 11, 13, 15, and 17 are TiO 2, respectively.
₂ , an even-numbered layer 2, 4, 6, 8, 10, 1 composed of a material containing at least one compound selected from the group consisting of ₂ , CeO ₂ , ZnS and Bi ₂ O ₃ as a main component.
2, 14, 16 and 18 are each made of a material containing as a main component at least one compound selected from the group consisting of MgF ₂ and SiO ₂ .

Here, a material containing at least one compound selected from the group consisting of TiO ₂ , CeO ₂ , ZnS and Bi ₂ O ₃ as a main component means TiO ₂ , CeO ₂ .
₂ , any one of ZnS and Bi ₂ O ₃ or a mixture of any two or more thereof (mixing ratio is arbitrary), or these as a main component (preferably 60% by weight or more in total,
(More preferably 80% by weight or more), and refers to a mixture containing other substances (including additives or unavoidable impurities, etc.), and among them, TiO substantially free of impurities
Any one of ₂ , CeO ₂ , ZnS or Bi ₂ O ₃ is preferable, and TiO ₂ or ZnS is more preferable.

Further, the material mainly composed of at least one compound selected from the group consisting of MgF ₂ and SiO _2, one of MgF ₂ or SiO ₂ one or a mixture of the two (the mixing ratio is arbitrary) Or, a mixture containing these as the main components (preferably 60% by weight or more in total, more preferably 80% by weight or more) and other substances (including additives or unavoidable impurities) is mentioned. , MgF ₂ or SiO containing substantially no impurities
₂ is preferred.

The odd-numbered layers may all have the same composition or different compositions. Similarly, the even-numbered layers may have the same composition or different compositions.

The refractive index (measured at a wavelength of 550 nm) of each odd-numbered layer is preferably 2.2 to 2.4, and 2.29 to 2.
38 is more preferable.

The refractive index (measured at a wavelength of 550 nm) of each even-numbered layer is preferably 1.3 to 1.5, and 1.37 to 1.
49 is more preferred.

By making the constituent materials of the layers 1 to 18 of the multilayer reflection increasing film 19 and the refractive index as described above,
An extremely high reflectance is obtained for both the S-polarized component and the P-polarized component, there is substantially no phase difference between the S-polarized component and the P-polarized component of the reflected light, and the effect is obtained in a wide wavelength range. Further, such a multilayer reflection increasing film 19 is less deteriorated and has excellent durability. Also, each layer 1-18
The adhesion of the film on the boundary surface between them and on the surface of the optical component 20 is also good, and cracks due to internal stress do not occur.

In the multilayer reflection increasing film 19, each of the layers 1 to 1
The optical film thickness of No. 8 is not particularly limited, but it is usually preferable to set it as follows. That is, the optical film thickness of each of the layers 1 to 18 is preferably about 0.15 to 0.35 times the central wavelength of the wavelength range in which reflection is desired to increase,
It is more preferably about 0.20 to 0.30 times, further preferably about 0.225 to 0.275 times.

The formation of the layers 1 to 18 is usually carried out by vacuum vapor deposition,
The film composition and the film thickness can be obtained by a vapor phase film forming method such as sputtering or ion plating, and the film forming conditions can be set. Reflection increasing film 1 as described above
9 has a wavelength of 570 to 710 nm, and a wavelength of 58.
It realizes high reflectance and no phase difference for incident light of 0 to 680 nm.

[0028]

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

(Example 1) [1] Production of multilayer reflection-increasing 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
Eight layers were sequentially formed to obtain the multilayer reflection increasing film of the present invention. In Table 1, the refractive index (measurement wavelength 550 nm) and film thickness of each layer are also shown.

[0030]

[Table 1]

[2] Measurement of Spectral Characteristics A light having a wavelength of 580 to 680 nm (design wavelength λ ₀ = 630 nm) is incident on the multilayer reflection increasing film at an incident angle of 45 °, and the S-polarized component and the P-polarized component are respectively reflected. Was measured. The results are shown in the graph of FIG.

As shown in this graph, the S polarization component (dotted line in the figure) achieves a reflectance of about 100% within a deviation of ± 50 nm from the design wavelength, and the P polarization component (solid line in the figure).
Shows a reflectance of about 98 when the deviation from the design wavelength is within ± 50 nm.
% Or more, and a reflectance of about 99% or more is achieved within ± 30 nm.

[3] Measurement of Phase Difference Light having a wavelength of 580 to 700 nm (design wavelength λ ₀ = 630 nm) is incident on the multilayer reflection increasing film at an incident angle of 45 °, and the S-polarized component and the P-polarized light in the reflected light are incident. The phase difference with the component was measured. The result is shown in the graph of FIG.

As shown in this graph, S polarization component and P
As for the phase difference with the polarization component, the deviation from the design wavelength is -50 to
Within ± 70 ° within the range of +70 nm.

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

[0036]

[Table 2]

[2] Measurement of Spectral Characteristics In the same manner as in Example 1, the reflectances of the S-polarized component and the P-polarized component were measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component (dotted line in the figure) achieves a reflectance of about 99% or more within a deviation of ± 50 nm from the design wavelength, and the P polarization component (solid line in the figure). Achieves a reflectance of about 95% or more within a deviation of ± 50 nm from the design wavelength, and a reflectance of about 98% or more within a deviation of ± 30 nm.

[3] Measurement of phase difference In the same manner as in Example 1, the S-polarized component and P in the reflected light were measured.
The phase difference with the polarized component was measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component and P
As for the phase difference with the polarization component, the deviation from the design wavelength is -50 to
Achieved within ± 4.0 ° within +70 nm.

(Example 3) [1] Production of multilayer reflection-increasing film After optical glass parts similar to those in Example 1 were precisely cleaned, they are shown in Table 3 below from the surface side of the optical glass parts by vacuum deposition. First to fourteenth layers made of materials were sequentially formed to obtain a multilayer reflection increasing film of the present invention. In Table 3, the refractive index (measurement wavelength 550 nm) and film thickness of each layer are also shown.

[0042]

[Table 3]

[2] Measurement of Spectral Characteristics In the same manner as in Example 1, the reflectances of the S-polarized component and the P-polarized component were measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component (dotted line in the figure) achieves a reflectance of about 99% or more within a deviation of ± 50 nm from the design wavelength, and the P polarization component (solid line in the figure). Achieves a reflectance of about 92% or more when the deviation from the design wavelength is within ± 50 nm, and a reflectance of about 96% or more within ± 30 nm.

[3] Measurement of Phase Difference Light having a wavelength of 570 to 700 nm (design wavelength λ ₀ = 630 nm) is incident on the above multilayer reflection increasing film at an incident angle of 45 °, and S polarization component and P polarization of reflected light The phase difference with the component was measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component and P
The phase difference with the polarization component is -60 to 60 degrees apart from the design wavelength.
Achieved within ± 5.0 ° in the range of +70 nm.

(Example 4) [1] Production of multilayer reflection-increasing film The same optical glass parts as in Example 1 were precision cleaned, and then vacuum-evaporated to show the surface side of the optical glass parts shown in Table 4 below. First to fourteenth layers made of materials were sequentially formed to obtain a multilayer reflection increasing film of the present invention. In addition, in Table 4, the refractive index (measurement wavelength 550 nm) and the film thickness of each layer are also shown.

[0048]

[Table 4]

[2] Measurement of Spectral Characteristics In the same manner as in Example 1, the reflectances of the S-polarized component and the P-polarized component were measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component (dotted line in the figure) achieves a reflectance of about 99% or more within a deviation of ± 50 nm from the design wavelength, and the P polarization component (solid line in the figure). Achieves a reflectance of about 92% or more when the deviation from the design wavelength is within ± 50 nm, and a reflectance of about 96% or more within ± 30 nm.

[3] Measurement of Phase Difference In the same manner as in Example 1, the S-polarized component and P in the reflected light
The phase difference with the polarized component was measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component and P
As for the phase difference with the polarization component, the deviation from the design wavelength is -50 to
Achieves within ± 3.0 ° in the range of +70 nm.

(Example 5) [1] Production of multilayer reflection-increasing film After optical glass parts similar to those in Example 1 were precision washed, the results are shown in Table 5 below from the surface side of the optical glass parts by vacuum deposition. First to twelfth layers made of materials were sequentially formed to obtain a multilayer reflection increasing film of the present invention. In Table 5, the refractive index (measurement wavelength 550 nm) and film thickness of each layer are also shown.

[0054]

[Table 5]

[2] Measurement of Spectral Characteristics In the same manner as in Example 1, the reflectances of the S-polarized component and the P-polarized component were measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component (dotted line in the figure) achieves a reflectance of about 98% or more within a deviation of ± 50 nm from the design wavelength, and the P polarization component (solid line in the figure). Achieves a reflectance of about 90% or more when the deviation from the design wavelength is within ± 50 nm, and a reflectance of about 93% or more within ± 30 nm.

[3] Measurement of Phase Difference In the same manner as in Example 3, the S-polarized component and P in the reflected light were measured.
The phase difference with the polarized component was measured. The result is shown in the graph of FIG.

As shown in this graph, S polarization component and P
The phase difference with the polarization component is -60 to 60 degrees apart from the design wavelength.
Achieves within ± 3.0 ° in the range of +70 nm.

(Example 6) [1] Production of multilayer reflection-increasing film After optical glass parts similar to those in Example 1 were precision cleaned, the results are shown in Table 6 below from the surface side of the optical glass parts by vacuum deposition. First to tenth layers made of materials were sequentially formed to obtain a multilayer reflection increasing film of the present invention. In Table 6, the refractive index (measurement wavelength: 550 nm) and film thickness of each layer are also shown.

[0060]

[Table 6]

[2] Measurement of Spectral Characteristics In the same manner as in Example 1, the reflectances of the S-polarized component and the P-polarized component were measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component (dotted line in the figure) achieves a reflectance of about 96% or more within a deviation of ± 50 nm from the design wavelength, and the P polarization component (solid line in the figure). Achieves a reflectance of about 83% or more when the deviation from the design wavelength is within ± 50 nm, and a reflectance of about 87% or more within ± 30 nm.

[3] Measurement of phase difference In the same manner as in Example 3, the S-polarized component and P in the reflected light were measured.
The phase difference with the polarized component was measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component and P
The phase difference with the polarization component is -60 to 60 degrees apart from the design wavelength.
Achieves within ± 3.0 ° in the range of +70 nm.

(Comparative Example) [1] Production of multilayer reflection-increasing film After optical glass parts similar to those in Example 1 were precision cleaned, the materials shown in Table 7 below were applied from the surface side of the optical glass parts by vacuum deposition. The first layer to the eighth layer composed of the above were sequentially formed to obtain a multilayer reflection increasing film of a comparative example. In Table 7, the refractive index (measurement wavelength 550 nm) and film thickness of each layer are also shown.

[0066]

[Table 7]

[2] Measurement of Spectral Characteristics In the same manner as in Example 1, the reflectances of the S-polarized component and the P-polarized component were measured. The result is shown in the graph of FIG.

As shown in this graph, the S polarization component (dotted line in the figure) has a reflectance of about 89% or more within a deviation of ± 50 nm from the design wavelength, and the P polarization component (solid line in the figure) is When the deviation from the wavelength is within ± 50 nm, the reflectance is about 71% or more, and within ± 30 nm, the reflectance is about 75% or more, both of which are lower than the reflectances obtained in Examples 1 to 6 above. ing.

[3] Measurement of phase difference In the same manner as in Example 1, the S-polarized component and P in the reflected light were measured.
The phase difference with the polarized component was measured. The result is shown in the graph of FIG.

As shown in this graph, S polarization component and P
As for the phase difference with the polarization component, the deviation from the design wavelength is -50 to
It is within ± 5.0 ° in the range of +70 nm.

Example 7 In each of Examples 1 to 6, the constituent material of the first layer, the fifth layer and the ninth layer was ZnS (refractive index: 2.37, film thickness: 66 nm). A similar multilayer reflection increasing film was manufactured except for the above.

On the other hand, when the spectral characteristics and the phase difference were measured in the same manner as in Examples 1 to 6, respectively, the high reflectance and the non-phase difference in a wide wavelength range similar to those in Examples 1 to 6 were obtained. Achieved

(Embodiment 8) In each of Embodiments 1 to 6, the constituent materials of the first layer, the fifth layer, the seventh layer and the ninth layer were respectively changed to CeO ₂ (refractive index: 2.31, film thickness). : 68
nm) and the other constituent materials of the odd-numbered layers were Bi ₂ O ₃ (refractive index: 2.38, film thickness: 66 nm), respectively.

On the other hand, when the spectral characteristics and the phase difference were measured in the same manner as in Examples 1 to 6, respectively, the high reflectance and the no-phase difference in a wide wavelength range similar to those in Examples 1 to 6 were obtained. Achieved

[0075]

As described above, according to the multilayer reflection increasing film of the present invention, a high reflectance can be obtained with a small number of layers, especially for both S-polarized light components and P-polarized light components. Moreover, a non-phase difference state between the S-polarized component and the P-polarized component of the reflected light can be obtained over a wide wavelength range.

Since the multilayer reflection increasing film of the present invention has a small number of layers, it is easy to manufacture and is excellent in stability and durability.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional side view showing a configuration example of a multilayer reflection increasing 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 3 of the present invention.

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

FIG. 6 is a graph showing spectral characteristics in Example 5 of the present invention.

FIG. 7 is a graph showing spectral characteristics in Example 6 of the present invention.

FIG. 8 is a graph showing spectral characteristics in a comparative example.

FIG. 9 is a graph showing a phase difference between the S-polarized component and the P-polarized component in Example 1 of the present invention.

FIG. 10 is a graph showing a phase difference between an S-polarized component and a P-polarized component in Example 2 of the present invention.

FIG. 11 is a graph showing a phase difference between an S-polarized component and a P-polarized component in Example 3 of the present invention.

FIG. 12 is a graph showing a phase difference between an S-polarized component and a P-polarized component in Example 4 of the present invention.

FIG. 13 is a graph showing a phase difference between an S-polarized component and a P-polarized component in Example 5 of the present invention.

FIG. 14 is a graph showing a phase difference between an S-polarized component and a P-polarized component in Example 6 of the present invention.

FIG. 15 is a graph showing a phase difference between an S-polarized component and a P-polarized component in a comparative example.

[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 12 12th layer 13th 13 layers 14 14th layer 15 15th layer 16 16th layer 17 17th layer 18 18th layer 19 Multilayer reflection increasing film 20 Optical parts

Claims (2)

[Claims] 1. A multilayer reflection increasing film formed by laminating an even number layer of 10 to 18 on a surface of an optical component used at an incident angle of 30 to 60 °, which is an odd number counted from the surface side. The second layer is Ti
O _2, at least one compound selected from CeO _2, the group consisting of ZnS and Bi ₂ O ₃ is formed of a material whose main component, even-numbered layers counted from the surface side, respectively, Mg
A multilayer reflection-increasing film comprising a material containing at least one compound selected from the group consisting of F ₂ and SiO ₂ as a main component. 2. The refractive index of the constituent material of the optical component is 1.
The multilayer reflection increasing film according to claim 1, which has a thickness of 50 to 1.54.