JP6338503B2 - Optical element and optical element manufacturing method - Google Patents
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- 230000003287 optical effect Effects 0.000 title claims description 83
- 238000004519 manufacturing process Methods 0.000 title claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 47
- 239000000758 substrate Substances 0.000 claims description 45
- 229910052782 aluminium Inorganic materials 0.000 claims description 31
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 31
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 26
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 18
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 17
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- 238000001228 spectrum Methods 0.000 claims description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 7
- 229910000484 niobium oxide Inorganic materials 0.000 claims description 7
- URLJKFSTXLNXLG-UHFFFAOYSA-N niobium(5+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Nb+5].[Nb+5] URLJKFSTXLNXLG-UHFFFAOYSA-N 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 239000010703 silicon Substances 0.000 claims description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 5
- KBTFDPDATPFLEE-UHFFFAOYSA-N niobium(5+) oxygen(2-) silicon(4+) Chemical compound [O-2].[Nb+5].[Si+4] KBTFDPDATPFLEE-UHFFFAOYSA-N 0.000 claims description 5
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 5
- 239000002994 raw material Substances 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 2
- 238000001000 micrograph Methods 0.000 claims description 2
- 239000010408 film Substances 0.000 description 53
- 238000000034 method Methods 0.000 description 22
- 239000000463 material Substances 0.000 description 17
- 239000011521 glass Substances 0.000 description 14
- 238000010586 diagram Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 238000002834 transmittance Methods 0.000 description 8
- 230000008569 process Effects 0.000 description 7
- 239000010409 thin film Substances 0.000 description 5
- 230000004888 barrier function Effects 0.000 description 4
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 229910000838 Al alloy Inorganic materials 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 229910001593 boehmite Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 description 2
- 238000007733 ion plating Methods 0.000 description 2
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 238000005546 reactive sputtering Methods 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000001771 vacuum deposition Methods 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- WMWXXXSCZVGQAR-UHFFFAOYSA-N dialuminum;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3] WMWXXXSCZVGQAR-UHFFFAOYSA-N 0.000 description 1
- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000005308 flint glass Substances 0.000 description 1
- 229910001195 gallium oxide Inorganic materials 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 description 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 238000002294 plasma sputter deposition Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 229910001936 tantalum oxide Inorganic materials 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- BYMUNNMMXKDFEZ-UHFFFAOYSA-K trifluorolanthanum Chemical compound F[La](F)F BYMUNNMMXKDFEZ-UHFFFAOYSA-K 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
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Description
本発明は、光学素子および光学素子の製造方法に関する。 The present invention relates to an optical element and a method for manufacturing the optical element.
従来、ガラス、プラスチックなどの透光性部材を用いたレンズ（透明基材）においては、表面反射による透過光の損失を低減するために光入射面に反射防止構造体（反射防止膜）が設けられている。 Conventionally, in a lens (transparent substrate) using a translucent member such as glass or plastic, an antireflection structure (antireflection film) is provided on the light incident surface in order to reduce the loss of transmitted light due to surface reflection. It has been.
例えば、特許文献１には、「透明基材の表面に、透明薄膜層、アルミナの水和物を主成分とする透明な微細凹凸層をこの順に備えてなる反射防止膜を備えた光学部材であって、前記透明薄膜層が、前記透明基材の屈折率と、前記微細凹凸層の屈折率との間の屈折率を有するものであり、前記透明薄膜層が、少なくとも窒化物層または酸窒化物層を含むことを特徴とする光学部材。」が記載されている（［請求項１］）。 For example, Patent Document 1 discloses that an optical member having an antireflection film comprising a transparent thin film layer and a transparent fine uneven layer mainly composed of an alumina hydrate in this order on the surface of a transparent substrate. The transparent thin film layer has a refractive index between the refractive index of the transparent substrate and the refractive index of the fine uneven layer, and the transparent thin film layer is at least a nitride layer or an oxynitride An optical member including a physical layer ”is described ([Claim 1]).
また、特許文献２には、「透明基材の表面に、透明薄膜層、アルミナの水和物を主成分とする透明な微細凹凸層をこの順に備えてなる反射防止膜を備えた光学部材であって、前記透明薄膜層が、前記基材側からアルミナ層と、該アルミナ層よりも低い屈折率を有し、かつ該アルミナ層に対する水をバリアする水バリア層と、該水バリア層よりも低い屈折率を有し、アルミナの水和物を主成分とする平坦層とを順に備えてなり、前記水バリア層の厚みが７０ｎｍ以下であることを特徴とする光学部材。」が記載されている（［請求項１］）。 Further, Patent Document 2 states that “an optical member including an antireflection film including a transparent thin film layer and a transparent fine uneven layer mainly composed of alumina hydrate in this order on the surface of a transparent substrate. The transparent thin film layer has an alumina layer from the substrate side, a water barrier layer having a lower refractive index than the alumina layer, and barriers water against the alumina layer, and more than the water barrier layer. An optical member having a low refractive index and a flat layer mainly composed of an alumina hydrate, wherein the water barrier layer has a thickness of 70 nm or less. ([Claim 1]).
更に、特許文献３には、「透明な基体と、アルミニウムを含有するターゲットを使用し窒素を含有するガス中でスパッタリングを行うことにより前記基体上に成膜されアルミニウムの一部が窒化された窒素含有アルミニウム膜を水中で加熱することにより前記基体上に形成された透明膜と、を備えたことを特徴とする光学部材。」が記載されており（［請求項５］）、窒素含有アルミニウム膜の厚みとして０．１〜１．０μｍが記載されており、窒素含有アルミニウム膜が不透明な黒色の膜となっていることが記載されている（［００２０］）。 Further, Patent Document 3 discloses that “a nitrogen in which a part of aluminum is nitrided by forming a film on the substrate by sputtering in a gas containing nitrogen using a transparent substrate and a target containing aluminum. An optical member comprising a transparent film formed on the substrate by heating the containing aluminum film in water ([Claim 5]), and a nitrogen-containing aluminum film. The thickness of 0.1 to 1.0 μm is described, and it is described that the nitrogen-containing aluminum film is an opaque black film ([0020]).
本発明者らは、特許文献１および２に記載された光学部材について検討したところ、反射防止性能は良好であったが、微細凹凸層を構成するアルミナ水和物の種類によっては、わずかに散乱光が発生し、光学部材の品位に影響を与える可能性があることを明らかとした。
また、本発明者らは、特許文献３に記載された光学部材について検討したところ、加熱処理前の窒素含有アルミニウム膜の厚みによっては、反射防止性能が劣るだけでなく、散乱光が発生し、光学部材の品位が劣る場合があることを明らかとした。
The present inventors examined the optical members described in Patent Documents 1 and 2 and found that the antireflection performance was good, but depending on the type of alumina hydrate constituting the fine uneven layer, it was slightly scattered. It has been clarified that light is generated, which may affect the quality of the optical member.
In addition, when the inventors examined the optical member described in Patent Document 3, depending on the thickness of the nitrogen-containing aluminum film before the heat treatment, not only the antireflection performance is inferior, but scattered light is generated, It has been clarified that the quality of the optical member may be inferior.
そこで、本発明は、良好な反射防止性能を維持し、散乱光の発生を抑制した光学素子およびその製造方法を提供することを課題とする。 Accordingly, an object of the present invention is to provide an optical element that maintains good antireflection performance and suppresses the generation of scattered light, and a method for manufacturing the same.
本発明者らは、上記課題を達成すべく鋭意検討した結果、空間周波数のピーク値（以下、「空間周波数ピーク」ともいう。）が特定の値を示す凹凸層を、反射防止膜として用いることにより、良好な反射防止性能を維持し、散乱光の発生を抑制できることを見出し、本発明を完成させた。
すなわち、以下の構成により上記課題を達成することができることを見出した。
As a result of intensive studies to achieve the above-mentioned problems, the present inventors use an uneven layer having a specific value of a spatial frequency peak value (hereinafter also referred to as “spatial frequency peak”) as an antireflection film. Thus, it was found that good antireflection performance can be maintained and the generation of scattered light can be suppressed, and the present invention has been completed.
That is, it has been found that the above-described problem can be achieved by the following configuration.
［１］ 透明基材と、反射防止膜とを有する光学素子であって、
反射防止膜が、アルミナの水和物を主成分とする透明な凹凸層を有し、
凹凸層の空間周波数のピーク値が、９μｍ-1よりも大きい、光学素子。
［２］ 凹凸層が、アルミニウムの窒化物に温水処理を施して得られるアルミナの水和物を主成分とする、［１］に記載の光学素子。
［３］ アルミニウムの窒化物が、透明である、［２］に記載の光学素子。
［４］ 反射防止膜が、透明基材と凹凸層との間に、さらに中間層を備え、
中間層が、透明基材の屈折率よりも低い屈折率を有する低屈折率層と、透明基材の屈折率よりも高い屈折率を有する高屈折率層とを、透明基材側からこの順に有する、［１］〜［３］のいずれかに記載の光学素子。
［５］ 反射防止膜が、透明基材と凹凸層との間に、さらに中間層を備え、
中間層が、透明基材の屈折率よりも高い屈折率を有する高屈折率層と、透明基材の屈折率よりも低い屈折率を有する低屈折率層とを、透明基材側からこの順に有する、［１］〜［３］のいずれかに記載の光学素子。
［６］ 低屈折率層がシリコン酸窒化物を含有し、高屈折率層がニオブ酸化物を含有する、［４］または［５］に記載の光学素子。
［７］ 低屈折率層がシリコン酸化物を含有し、高屈折率層がシリコンニオブ酸化物を含有する、［４］または［５］に記載の光学素子。
［８］ ［１］〜［７］のいずれかに記載の光学素子を作製する光学素子の製造方法であって、
透明基材上に、厚みが１００ｎｍ未満の窒素を含有するアルミニウム膜を形成する膜形成工程と、
アルミニウム膜に温水処理を施し、アルミナの水和物を主成分とする凹凸層を形成する温水処理工程と有する、光学素子の製造方法。
［９］ 温水処理工程が、アルミニウム膜に、電気抵抗率が１０ＭΩ・ｃｍ以上の純水を原料に含む処理液中で温水処理を施す工程である、［８］に記載の光学素子の製造方法。
[1] An optical element having a transparent substrate and an antireflection film,
The antireflection film has a transparent uneven layer mainly composed of alumina hydrate,
An optical element in which the peak value of the spatial frequency of the uneven layer is larger than 9 μm −1 .
[2] The optical element according to [1], wherein the concavo-convex layer is mainly composed of an alumina hydrate obtained by subjecting an aluminum nitride to a hot water treatment.
[3] The optical element according to [2], wherein the aluminum nitride is transparent.
[4] The antireflection film further includes an intermediate layer between the transparent substrate and the uneven layer,
The intermediate layer includes a low refractive index layer having a refractive index lower than that of the transparent substrate, and a high refractive index layer having a refractive index higher than that of the transparent substrate in this order from the transparent substrate side. The optical element according to any one of [1] to [3].
[5] The antireflection film further includes an intermediate layer between the transparent substrate and the uneven layer,
The intermediate layer includes a high refractive index layer having a refractive index higher than that of the transparent substrate, and a low refractive index layer having a refractive index lower than that of the transparent substrate in this order from the transparent substrate side. The optical element according to any one of [1] to [3].
[6] The optical element according to [4] or [5], wherein the low refractive index layer contains silicon oxynitride and the high refractive index layer contains niobium oxide.
[7] The optical element according to [4] or [5], wherein the low refractive index layer contains silicon oxide and the high refractive index layer contains silicon niobium oxide.
[8] An optical element manufacturing method for manufacturing the optical element according to any one of [1] to [7],
A film forming step of forming an aluminum film containing nitrogen having a thickness of less than 100 nm on a transparent substrate;
A method of manufacturing an optical element, comprising: a hot water treatment step of performing a hot water treatment on an aluminum film to form an uneven layer mainly composed of alumina hydrate.
[9] The method for producing an optical element according to [8], wherein the hot water treatment step is a step of performing a hot water treatment on the aluminum film in a treatment solution containing pure water having an electrical resistivity of 10 MΩ · cm or more as a raw material. .
本発明によれば、良好な反射防止性能を維持し、散乱光の発生を抑制した光学素子およびその製造方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the optical element which maintained favorable antireflection performance and suppressed generation | occurrence | production of scattered light, and its manufacturing method can be provided.
以下、本発明について詳細に説明する。
以下に記載する構成要件の説明は、本発明の代表的な実施態様に基づいてなされることがあるが、本発明はそのような実施態様に限定されるものではない。
なお、本明細書において、「〜」を用いて表される数値範囲は、「〜」の前後に記載される数値を下限値および上限値として含む範囲を意味する。
Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
［光学素子］
本発明の光学素子は、透明基材と、反射防止膜とを有する光学素子であって、反射防止膜が、アルミナの水和物を主成分とする透明な凹凸層を有し、凹凸層の空間周波数のピーク値が、９μｍ-1よりも大きい、光学素子である。
[Optical element]
The optical element of the present invention is an optical element having a transparent base material and an antireflection film, and the antireflection film has a transparent uneven layer mainly composed of alumina hydrate, The optical element has a spatial frequency peak value larger than 9 μm −1 .
本発明の光学素子は、上述した通り、空間周波数のピーク値が特定の値を示す凹凸層を反射防止膜として用いることにより、良好な反射防止性能が維持され、散乱光の発生を抑制することができる。
このような効果（特に、散乱光の発生を抑制する効果）が得られる理由は、詳細には明らかではないが、およそ以下のとおりと推測される。
まず、本発明者らは、従来公知の光学部材において散乱光が発生する原因に関して、凹凸層に入射光の波長程度のサイズの長周期の揺らぎが存在すると、光の散乱に影響を与えることになるとの推察に基づき鋭意検討した結果、散乱光強度と凹凸層の空間周波数のピーク値との間に相関があることを新たに知見している。
そして、本発明者らは、空間周波数のピーク値が高周波数側にあるほど散乱光強度が小さくなることを見出している。
そのため、空間周波数のピーク値が９μｍ-1よりも大きいことにより、可視光の回折および散乱に寄与する空間周波数成分が相対的に減少したことにより、散乱光の発生が抑制されたと考えられる。
As described above, the optical element according to the present invention maintains an excellent antireflection performance and suppresses the generation of scattered light by using an uneven layer having a specific value of the spatial frequency peak value as an antireflection film. Can do.
The reason why such an effect (in particular, an effect of suppressing the generation of scattered light) is obtained is not clear in detail, but is presumed as follows.
First, regarding the cause of the occurrence of scattered light in a conventionally known optical member, the present inventors have an influence on light scattering when the irregular layer has a long-period fluctuation of the size of the incident light wavelength. As a result of intensive studies based on the presumption that it becomes, it has been newly found that there is a correlation between the scattered light intensity and the peak value of the spatial frequency of the uneven layer.
The inventors have found that the scattered light intensity decreases as the peak value of the spatial frequency is higher.
Therefore, it is considered that the generation of scattered light is suppressed because the peak value of spatial frequency is larger than 9 μm −1 and the spatial frequency component contributing to the diffraction and scattering of visible light is relatively reduced.
以下に、本発明の光学素子の全体の構成（概要）について図１を用いて説明した後に、各構成の材料等について詳述する。 Hereinafter, the overall configuration (outline) of the optical element of the present invention will be described with reference to FIG.
図１は、本発明の光学素子の実施態様の一例を示す模式的な断面図である。
図１に示す通り、本発明の光学素子１は、透明基材２と、反射防止膜３とを有する。
また、反射防止膜３は、アルミナの水和物を主成分とする透明な凹凸層４を有しており、図１に示す通り、透明基材２と凹凸層４との間に、さらに中間層５を有しているのが好ましい。
FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of the optical element of the present invention.
As shown in FIG. 1, the optical element 1 of the present invention has a transparent substrate 2 and an antireflection film 3.
The antireflection film 3 has a transparent uneven layer 4 mainly composed of alumina hydrate. As shown in FIG. 1, an intermediate layer is formed between the transparent substrate 2 and the uneven layer 4. It is preferable to have a layer 5.
〔透明基材〕
本発明の光学素子が有する透明基材は特に限定されず、例えば、平板レンズ、凹レンズ、凸レンズなど主として光学装置において用いられる透明の光学部材が挙げられる。
また、透明基材の形状は特に限定されず、例えば、正または負の曲率を有する曲面と平面の組合せで構成された形状であってもよい。
また、透明基材の材料としては、例えば、ガラス、プラスチック等が挙げられる。
ここで、「透明」とは、３５０〜８５０ｎｍの波長領域の光に対して透過率が１０％以上であることをいい、後述する凹凸層やアルミニウムの窒化物についても同様である。
(Transparent substrate)
The transparent base material which the optical element of this invention has is not specifically limited, For example, the transparent optical member mainly used in an optical apparatus, such as a flat lens, a concave lens, and a convex lens, is mentioned.
The shape of the transparent substrate is not particularly limited, and may be, for example, a shape constituted by a combination of a curved surface having a positive or negative curvature and a flat surface.
Examples of the material for the transparent substrate include glass and plastic.
Here, “transparent” means that the transmittance is 10% or more with respect to light in the wavelength region of 350 to 850 nm, and the same applies to an uneven layer and aluminum nitride described later.
上記透明基材の屈折率は、１．６５超１．７４未満であるのが好ましい。
この屈折率を満たす材料としては、具体的には、例えば、Ｓ−ＮＢＨ５（オハラ社製）、Ｓ−ＬＡＬ１８（オハラ社製）、ＭＲ−７（三井化学社製）、ＭＲ−１７４（三井化学社製）などの市販品のほか、一般的なランタンガラス、フリントガラス、チオウレタン系樹脂、エピスルフィト系樹脂等が挙げられる。
The refractive index of the transparent substrate is preferably more than 1.65 and less than 1.74.
Specific examples of materials that satisfy this refractive index include, for example, S-NBH5 (Ohara), S-LAL18 (Ohara), MR-7 (Mitsui Chemicals), MR-174 (Mitsui Chemicals). In addition to commercially available products such as those manufactured by the company, general lanthanum glass, flint glass, thiourethane resin, episulfite resin, and the like can be given.
〔反射防止膜〕
本発明の光学素子が有する反射防止膜は、上述した通り、アルミナの水和物を主成分とする透明な凹凸層を有し、また、反射防止性能がより良好となる理由から、透明基材と凹凸層との間に中間層を有しているのが好ましい。
[Antireflection film]
As described above, the antireflection film of the optical element of the present invention has a transparent concavo-convex layer mainly composed of an alumina hydrate, and the antireflection performance is improved, so that the transparent substrate It is preferable to have an intermediate layer between the concave and convex layers.
＜凹凸層＞
上記凹凸層は、アルミナの水和物を主成分とする透明な凹凸層であり、反射防止すべき光の波長よりも小さい平均凸部間距離（平均ピッチ）を有する凹凸構造を有する層をいう。なお、反射防止すべき光の波長が数百ｎｍ以下であるような場合、凹凸構造の平均凸部間距離もサブミクロンの大きさとなるため、凹凸構造は微細凹凸構造とも言うことができ、凹凸層は微細凹凸層とも言うことができる。
ここで、「主成分」とは、アルミナの水和物（ベーマイトとも呼ばれる酸化アルミニウム水和物）が凹凸層を構成する成分の８０質量％以上であることをいう。
また、「凸部間距離」（ピッチ）とは、凹部を隔てた最隣接凸部の頂点同士の距離をいい、「平均凸部間距離」（平均ピッチ）とは、凹凸層の表面を走査型電子顕微鏡（Scanning Electron Microscope：ＳＥＭ）で撮影した画像（以下、「ＳＥＭ画像」と略す。）に画像処理を施して２値化し、統計的処理によって求めた値をいう。
なお、平均凸部間距離（平均ピッチ）は、数１０ｎｍ〜数１００ｎｍオーダーであり、１５０ｎｍ以下であることが好ましく、１００ｎｍ以下がより好ましい。
<Uneven layer>
The concavo-convex layer is a transparent concavo-convex layer mainly composed of alumina hydrate and has a concavo-convex structure having an average inter-convex distance (average pitch) smaller than the wavelength of light to be prevented from being reflected. . Note that when the wavelength of light to be prevented from being reflected is several hundred nm or less, the average convex-to-convex distance of the concavo-convex structure is also submicron, so the concavo-convex structure can also be referred to as a fine concavo-convex structure. The layer can also be referred to as a fine uneven layer.
Here, the “main component” means that alumina hydrate (aluminum oxide hydrate, also called boehmite) is 80% by mass or more of the components constituting the uneven layer.
The “distance between protrusions” (pitch) is the distance between the vertices of the nearest protrusions across the recess, and the “average distance between protrusions” (average pitch) scans the surface of the uneven layer. An image taken with a scanning electron microscope (SEM) (hereinafter abbreviated as “SEM image”) is subjected to image processing, binarized, and a value obtained by statistical processing.
The average inter-convex distance (average pitch) is on the order of several tens of nm to several hundreds of nm, preferably 150 nm or less, and more preferably 100 nm or less.
上記凹凸層の厚みは、５０〜４００ｎｍであるのが好ましく、１００〜３００ｎｍであるのがより好ましい。
ここで、「凹凸層の厚み」とは、凸部頂点から、凹凸層と中間層（中間層がない場合は透明基材）との界面までの垂線線の長さをいう。
なお、後述する本発明の光学素子の製造方法においては、温水処理を施す前のアルミニウム膜の厚みを１００ｎｍ未満と規定しているが、後述する実施例にも示す通り、温水処理後に形成される凹凸層の厚みは、温水処理を施す前のアルミニウム膜の厚みよりも厚くなるものである。
The thickness of the uneven layer is preferably 50 to 400 nm, and more preferably 100 to 300 nm.
Here, the “thickness of the concavo-convex layer” refers to the length of a perpendicular line from the apex of the convex portion to the interface between the concavo-convex layer and the intermediate layer (or a transparent substrate when there is no intermediate layer).
In addition, in the manufacturing method of the optical element of this invention mentioned later, although the thickness of the aluminum film before performing a warm water process is prescribed | regulated as less than 100 nm, as shown also in the Example mentioned later, it forms after a warm water process. The thickness of the concavo-convex layer is greater than the thickness of the aluminum film before the hot water treatment.
上記凹凸層の空間周波数のピーク値は、９μｍ-1よりも大きければ特に限定されないが、１０μｍ-1以上３０μｍ-1以下であるのが好ましい。
ここで、「凹凸層の空間周波数のピーク値」とは、凹凸層表面のＳＥＭ画像を二次元フーリエ変換し、得られる二次元の空間周波数強度スペクトルを方位角方向に積算して算出される、空間周波数の大きさに対応する強度スペクトルのピーク値をいう。
The peak value of the spatial frequency of the uneven layer is not particularly limited as long as it is larger than 9 μm −1 , but is preferably 10 μm −1 or more and 30 μm −1 or less.
Here, the “peak value of the spatial frequency of the concavo-convex layer” is calculated by two-dimensional Fourier transform of the SEM image on the surface of the concavo-convex layer and integrating the obtained two-dimensional spatial frequency intensity spectrum in the azimuth direction. The peak value of the intensity spectrum corresponding to the magnitude of the spatial frequency.
本発明においては、上記凹凸層は、散乱光の発生をより抑制できる理由から、アルミニウムの窒化物（以下、「アルミ窒化物」とも略す。）に温水処理を施して得られるアルミナの水和物を主成分とするのが好ましく、反射防止性能がより良好となる理由から、透明なアルミ窒化物に温水処理を施して得られるアルミナの水和物を主成分とするのがより好ましい。 In the present invention, the concavo-convex layer is a hydrate of alumina obtained by subjecting an aluminum nitride (hereinafter also abbreviated as “aluminum nitride”) to hot water treatment because the generation of scattered light can be further suppressed. It is preferable that the main component is an alumina hydrate, and it is more preferable that the main component is an alumina hydrate obtained by subjecting a transparent aluminum nitride to a hot water treatment.
＜中間層＞
上記中間層は、上記透明基材と上記凹凸層との屈折率段差に由来する反射光を干渉により抑制することを目的とする層であり、本発明においては、透明基材の屈折率よりも低い屈折率を有する低屈折率層および透明基材の屈折率よりも高い屈折率を有する高屈折率層の少なくとも２層からなる中間層が好ましい。
<Intermediate layer>
The intermediate layer is a layer for the purpose of suppressing reflected light derived from a refractive index step between the transparent base material and the uneven layer by interference. In the present invention, the intermediate layer is more than the refractive index of the transparent base material. An intermediate layer composed of at least two layers of a low refractive index layer having a low refractive index and a high refractive index layer having a refractive index higher than that of the transparent substrate is preferable.
中間層の具体的な態様としては、例えば、透明基材側から、低屈折率層および高屈折率層をこの順に有する態様；高屈折率層および低屈折率層をこの順に有する態様；低屈折率層、高屈折率層、低屈折率層および高屈折率層をこの順に有する態様；高屈折率層、低屈折率層、高屈折率層および低屈折率層をこの順に有する態様；低屈折率層、高屈折率層、低屈折率層、高屈折率層、低屈折率層および高屈折率層をこの順に有する態様；高屈折率層、低屈折率層、高屈折率層、低屈折率層、高屈折率層および低屈折率層をこの順に有する態様；等が挙げられる。 Specific embodiments of the intermediate layer include, for example, an embodiment having a low refractive index layer and a high refractive index layer in this order from the transparent substrate side; an embodiment having a high refractive index layer and a low refractive index layer in this order; An aspect having a refractive index layer, a high refractive index layer, a low refractive index layer and a high refractive index layer in this order; an aspect having a high refractive index layer, a low refractive index layer, a high refractive index layer and a low refractive index layer in this order; A mode having a refractive index layer, a high refractive index layer, a low refractive index layer, a high refractive index layer, a low refractive index layer and a high refractive index layer in this order; a high refractive index layer, a low refractive index layer, a high refractive index layer, a low refractive index An embodiment having a refractive index layer, a high refractive index layer, and a low refractive index layer in this order; and the like.
ここで、低屈折率層および高屈折率層の屈折率は、隣接する層と相対的に決まるため特に限定されないが、低屈折率層の屈折率は１．４５〜１．８程度であるのが好ましく、高屈折率層の屈折率は１．６〜２．４程度であるのが好ましい。
また、低屈折率層および高屈折率層の厚みは、それぞれ、屈折率と反射光波長等との関係から適宜設定すればよいが、低屈折率層の厚みは８〜１６０ｎｍ程度であるのが好ましく、高屈折率層の厚みは４〜１６ｎｍ程度であるのが好ましい。
Here, the refractive indexes of the low refractive index layer and the high refractive index layer are not particularly limited because they are determined relative to the adjacent layers, but the refractive index of the low refractive index layer is about 1.45 to 1.8. The refractive index of the high refractive index layer is preferably about 1.6 to 2.4.
The thicknesses of the low refractive index layer and the high refractive index layer may be set as appropriate based on the relationship between the refractive index and the reflected light wavelength. The thickness of the low refractive index layer is about 8 to 160 nm. The thickness of the high refractive index layer is preferably about 4 to 16 nm.
低屈折率層の材料としては、具体的には、例えば、シリコン酸化物、シリコン酸窒化物、ガリウム酸化物、アルミ酸化物、ランタン酸化物、ランタンフッ化物、マグネシウムフッ化物などが挙げられる。
高屈折率層の材料としては、具体的には、例えば、ニオブ酸化物、シリコンニオブ酸化物、ジルコニウム酸化物、タンタル酸化物、シリコン窒化物、チタン酸化物などが挙げられる。
これらのうち、低屈折率層がシリコン酸窒化物を含有し、かつ、高屈折率層がニオブ酸化物を含有するのが好ましく、同様に、低屈折率層がシリコン酸化物を含有し、高屈折率層がシリコンニオブ酸化物を含有するのが好ましい。
Specific examples of the material for the low refractive index layer include silicon oxide, silicon oxynitride, gallium oxide, aluminum oxide, lanthanum oxide, lanthanum fluoride, and magnesium fluoride.
Specific examples of the material for the high refractive index layer include niobium oxide, silicon niobium oxide, zirconium oxide, tantalum oxide, silicon nitride, and titanium oxide.
Of these, the low refractive index layer preferably contains silicon oxynitride, and the high refractive index layer preferably contains niobium oxide. Similarly, the low refractive index layer contains silicon oxide, and high The refractive index layer preferably contains silicon niobium oxide.
このような低屈折率層および高屈折率層からなる中間層は、真空蒸着、プラズマスパッタ、電子サイクロトロンスパッタ、イオンプレーティングなどの気相成膜法により、各層を形成し、作製することができる。 Such an intermediate layer composed of a low refractive index layer and a high refractive index layer can be produced by forming each layer by a vapor deposition method such as vacuum deposition, plasma sputtering, electron cyclotron sputtering, or ion plating. .
［光学素子の製造方法］
本発明の光学素子の製造方法（以下、「本発明の製造法」とも略す。）は、上述した本発明の光学素子を作製する光学素子の製造方法であって、透明基材上に、厚みが１００ｎｍ未満の窒素を含有するアルミニウム膜を形成する膜形成工程と、アルミニウム膜に温水処理を施し、アルミナの水和物を主成分とする凹凸層を形成する温水処理工程と有する、光学素子の製造方法である。
以下に、各処理工程における材料や条件について詳述する。なお、透明基材は、上述した本発明の光学素子における透明基材と同様である。
[Method for Manufacturing Optical Element]
The optical element manufacturing method of the present invention (hereinafter also abbreviated as “the manufacturing method of the present invention”) is a manufacturing method of the optical element for manufacturing the above-described optical element of the present invention. A film forming step of forming an aluminum film containing nitrogen of less than 100 nm, and a hot water treatment step of performing a hot water treatment on the aluminum film to form an uneven layer mainly composed of alumina hydrate. It is a manufacturing method.
Hereinafter, materials and conditions in each processing step will be described in detail. The transparent substrate is the same as the transparent substrate in the above-described optical element of the present invention.
〔膜形成工程〕
上記膜形成工程は、透明基材上に、厚みが１００ｎｍ未満の窒素を含有するアルミニウム膜を形成する膜形成工程である。
ここで、アルミニウム膜は、アルミニウムまたはアルミニウムの合金もしくは化合物を主成分とする窒素を含有する金属膜であれば特に限定されないが、後述する温水処理により形成される凹凸層の空間周波数のピーク値がより高い値となり、その結果、得られる光学素子における散乱光の発生をより抑制できる理由から、アルミ窒化物を含有する膜であるのが好ましく、反射防止性能がより良好となる理由から、透明なアルミ窒化物を含有する膜であるのがより好ましい。
また、「主成分」とは、アルミニウムまたはアルミニウムの合金もしくは化合物がアルミニウム膜を構成する成分の８０質量％以上であることをいう。
[Film formation process]
The film forming step is a film forming step of forming an aluminum film containing nitrogen having a thickness of less than 100 nm on a transparent substrate.
Here, the aluminum film is not particularly limited as long as it is a metal film containing nitrogen whose main component is aluminum or an aluminum alloy or compound, but the peak value of the spatial frequency of the concavo-convex layer formed by hot water treatment described later is As a result, a film containing aluminum nitride is preferable because the generation of scattered light in the obtained optical element can be further suppressed, and transparent because it has better antireflection performance. A film containing aluminum nitride is more preferable.
The “main component” means that aluminum or an aluminum alloy or compound is 80% by mass or more of the components constituting the aluminum film.
上記アルミニウム膜の厚みは、１００ｎｍ未満であれば特に限定されないが、４０〜８０ｎｍであるのが好ましい。 Although the thickness of the said aluminum film will not be specifically limited if it is less than 100 nm, It is preferable that it is 40-80 nm.
このようなアルミニウム膜の形成方法は特に限定されず、例えば、反応性スパッタリング、真空蒸着、イオンプレーティングなどの気相成膜により形成することができる。 The method for forming such an aluminum film is not particularly limited. For example, the aluminum film can be formed by vapor deposition such as reactive sputtering, vacuum deposition, or ion plating.
〔温水処理工程〕
温水処理工程は、アルミニウム膜に温水処理を施し、アルミナの水和物を主成分とする凹凸層を形成する工程である。
ここで、温水処理は特に限定されず、例えば、（１）６０℃以上沸騰温度以下の温水（沸騰水も含む）に１分以上浸漬する方法（以下、「Ａ方法」という。）、（２）６０℃以上沸騰温度以下のアルカリ水溶液に１分以上浸漬する方法（以下、「Ｂ方法」という。）、（３）水蒸気にさらす方法、などが挙げられる。
このような温水処理を施すことにより、透明基材上に形成したアルミニウム膜が解膠作用等を受け、アルミナの水和物に転化され、凹凸層が形成される。
[Hot water treatment process]
The warm water treatment step is a step of performing a warm water treatment on the aluminum film to form an uneven layer mainly composed of alumina hydrate.
Here, the hot water treatment is not particularly limited. For example, (1) a method of immersing in hot water (including boiling water) of 60 ° C. or higher and boiling temperature or lower for 1 minute or longer (hereinafter referred to as “Method A”), (2 ) A method of immersing in an alkaline aqueous solution at 60 ° C. or higher and a boiling temperature or lower for 1 minute or longer (hereinafter referred to as “Method B”), (3) a method of exposing to water vapor, and the like.
By performing such a hot water treatment, the aluminum film formed on the transparent substrate is subjected to a peptizing action and the like, and is converted into an alumina hydrate to form an uneven layer.
本発明においては、上記温水処理が、上述したＡ方法またはＢ方法であるのが好ましく、温水ないしアルカリ水溶液の原料に用いる水として、電気抵抗率が１０ＭΩ・ｃｍ以上の純水を用いるのがより好ましい。
なお、電気抵抗率は、水温２５℃における電気抵抗率とする。
In the present invention, the hot water treatment is preferably the above-described method A or B, and it is more preferable to use pure water having an electrical resistivity of 10 MΩ · cm or more as water used as a raw material for warm water or an alkaline aqueous solution. preferable.
The electrical resistivity is the electrical resistivity at a water temperature of 25 ° C.
以下に実施例に基づいて本発明をさらに詳細に説明する。以下の実施例に示す材料、使用量、割合、処理内容、処理手順等は、本発明の趣旨を逸脱しない限り適宜変更することができる。したがって、本発明の範囲は以下に示す実施例により限定的に解釈されるべきものではない。 Hereinafter, the present invention will be described in more detail based on examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.
〔実施例１〕
ガラス（硝材）からなる透明基材（Ｓ−ＮＢＨ５、屈折率：１．６５９、オハラ社製）上に、低屈折率層としてシリコン酸窒化物（屈折率１．５１５）を用い、かつ、高屈折率層としてニオブ酸化物（屈折率２．３３０）を用いた下記表１に示す中間層を積層した。なお、各実施例における屈折率の値は、いずれも、波長５４０ｎｍの光に対する屈折率を表す。
次いで、中間層上に、アルミニウム膜としてアルミ窒化物（ＡｌＮ）を厚み４０ｎｍとなるように形成した。
その後、温水に浸漬させることにより、アルミナの水和物を主成分とする透明な凹凸層を形成された光学素子が得られた。なお、温水に浸漬させる前、すなわち、温水処理を施す前のアルミニウム膜（ＡｌＮ）について、分光光度計Ｕ−４０００（日立）を用いて１２°入射時の透過率を測定したところ、図９に示す通り、３５０〜８５０ｎｍにわたって７０％以上の透過率を示した。
ここで、シリコン酸窒化物、ニオブ酸化物およびアルミ窒化物は、いずれも反応性スパッタリングにより成膜した。また、温水処理としては、１００℃に加熱した温水に３分浸漬させて行い、温水処理液としては、電気抵抗率１２ＭΩ・ｃｍの超純水を用いた。
[Example 1]
A silicon oxynitride (refractive index 1.515) is used as a low refractive index layer on a transparent base material (S-NBH5, refractive index: 1.659, manufactured by OHARA) made of glass (glass material), and high An intermediate layer shown in Table 1 below using a niobium oxide (refractive index: 2.330) as a refractive index layer was laminated. In addition, the value of the refractive index in each Example represents the refractive index with respect to light with a wavelength of 540 nm.
Next, aluminum nitride (AlN) was formed as an aluminum film on the intermediate layer so as to have a thickness of 40 nm.
Then, the optical element in which the transparent uneven | corrugated layer which has an alumina hydrate as a main component was formed was obtained by being immersed in warm water. In addition, when the transmittance | permeability at the time of 12 degree incidence was measured using the spectrophotometer U-4000 (Hitachi) about the aluminum film (AlN) before performing a hot water process before being immersed in warm water, it is in FIG. As shown, a transmittance of 70% or more was exhibited over 350 to 850 nm.
Here, silicon oxynitride, niobium oxide, and aluminum nitride were all formed by reactive sputtering. Further, the warm water treatment was performed by immersing in warm water heated to 100 ° C. for 3 minutes, and ultrapure water having an electrical resistivity of 12 MΩ · cm was used as the warm water treatment liquid.
〔実施例２〕
ガラス（硝材）からなる透明基材（Ｓ−ＬＡＨ５５Ｖ、屈折率：１．８４０、オハラ社製）上に、低屈折率層としてシリコン酸化物（屈折率１．４６０）を用い、かつ、高屈折率層としてシリコンニオブ酸化物（屈折率２．１９７）を用いた下記表２に示す中間層を積層し、アルミ窒化物（ＡｌＮ）の厚みを８０ｎｍとした以外は、実施例１と同様の方法により、光学素子を作製した。
なお、実施例１と同様、温水処理を施す前のアルミニウム膜（ＡｌＮ）について、分光光度計Ｕ−４０００（日立）を用いて１２°入射時の透過率を測定したところ、図９に示す通り、３５０〜８５０ｎｍにわたって７０％以上の透過率を示した。
[Example 2]
On a transparent substrate (S-LAH55V, refractive index: 1.840, manufactured by OHARA) made of glass (glass material), silicon oxide (refractive index 1.460) is used as a low refractive index layer, and high refraction is achieved. The same method as in Example 1 except that the intermediate layer shown in Table 2 below using silicon niobium oxide (refractive index 2.197) as the refractive index layer is laminated and the thickness of the aluminum nitride (AlN) is 80 nm. Thus, an optical element was produced.
In addition, when the transmittance | permeability at the time of 12 degree incidence was measured using the spectrophotometer U-4000 (Hitachi) about the aluminum film (AlN) before performing a warm water process similarly to Example 1, as shown in FIG. The transmittance was 70% or more over 350 to 850 nm.
〔実施例３〕
ガラス（硝材）からなる透明基材（Ｓ−ＦＰＭ２、屈折率：１．５９８、オハラ社製）を用い、アルミ窒化物（ＡｌＮ）の厚みを８０ｎｍとし、中間層を形成しなかった以外は、実施例１と同様の方法により、光学素子を作製した。
Example 3
Except for using a transparent substrate made of glass (glass material) (S-FPM2, refractive index: 1.598, manufactured by OHARA), the thickness of aluminum nitride (AlN) was 80 nm, and no intermediate layer was formed. An optical element was produced in the same manner as in Example 1.
〔実施例４〕
ガラス（硝材）からなる透明基材（Ｓ−ＮＢＨ５、屈折率：１．６５９、オハラ社製）上に、低屈折率層としてシリコン酸窒化物（屈折率１．５１５）を用い、かつ、高屈折率層としてニオブ酸化物（屈折率２．３３０）を用いた下記表３に示す中間層を積層し、実施例１と同様の方法により、光学素子を作製した。
なお、実施例１と同様、温水処理を施す前のアルミニウム膜（ＡｌＮ）について、分光光度計Ｕ−４０００（日立）を用いて１２°入射時の透過率を測定したところ、図９に示す実施例１と同様の透過率が得られた。
Example 4
A silicon oxynitride (refractive index 1.515) is used as a low refractive index layer on a transparent base material (S-NBH5, refractive index: 1.659, manufactured by OHARA) made of glass (glass material), and high An intermediate layer shown in the following Table 3 using niobium oxide (refractive index: 2.330) as a refractive index layer was laminated, and an optical element was produced in the same manner as in Example 1.
In addition, when the transmittance | permeability at the time of 12 degree incidence was measured using the spectrophotometer U-4000 (Hitachi) about the aluminum film (AlN) before performing a hot water process similarly to Example 1, implementation shown in FIG. The same transmittance as in Example 1 was obtained.
〔比較例１〕
アルミ窒化物（厚み：４０ｎｍ）に代えて、Ａｌ2Ｏ3膜（厚み：６５ｎｍ）を用いた以外は、実施例１と同様の方法により、光学素子を作製した。
[Comparative Example 1]
An optical element was fabricated in the same manner as in Example 1 except that an Al 2 O 3 film (thickness: 65 nm) was used instead of aluminum nitride (thickness: 40 nm).
〔比較例２〕
アルミ窒化物（厚み：４０ｎｍ）に代えて、Ａｌ膜（厚み：４０ｎｍ）を用いた以外は、実施例１と同様の方法により、光学素子を作製した。
[Comparative Example 2]
An optical element was produced in the same manner as in Example 1 except that an Al film (thickness: 40 nm) was used instead of aluminum nitride (thickness: 40 nm).
作製した各光学素子について、以下に示す方法で、空間周波数ピーク、散乱光量、反射率および拡散反射率を測定した。 About each produced optical element, the spatial frequency peak, the scattered light amount, the reflectance, and the diffuse reflectance were measured by the method shown below.
＜空間周波数ピーク＞
各光学素子の凹凸層側の表面を走査型電子顕微鏡Ｓ−４１００（日立社製）で撮像した電子顕微鏡画像（倍率３万倍、加速電圧７．０ｋＶ）に、画像処理ソフトＩｇｏｒを用いて二次元Ｆｏｕｒｉｅｒ変換を施した。
次いで、得られた二次元の空間周波数強度スペクトルを方位角方向に積算し、空間周波数の大きさに対応するスペクトルの強度を算出した。
結果を下記表４に示す。また、実施例１（ピーク：１４μｍ-1）、実施例２（ピーク：１０μｍ-1）、比較例１（ピーク：５μｍ-1）および比較例２（ピーク：７μｍ-1）で作製し光学素子における凹凸層表面を走査型電子顕微鏡で撮影した画像と空間周波数スペクトルとを図３に示す。
<Spatial frequency peak>
Using an image processing software Igor, an electron microscope image (magnification 30,000 times, acceleration voltage 7.0 kV) obtained by imaging the surface of the concavo-convex layer side of each optical element with a scanning electron microscope S-4100 (manufactured by Hitachi). Dimensional Fourier transform was performed.
Next, the obtained two-dimensional spatial frequency intensity spectrum was integrated in the azimuth direction, and the spectrum intensity corresponding to the magnitude of the spatial frequency was calculated.
The results are shown in Table 4 below. Further, optical elements manufactured in Example 1 (peak: 14 μm −1 ), Example 2 (peak: 10 μm −1 ), Comparative Example 1 (peak: 5 μm −1 ), and Comparative Example 2 (peak: 7 μm −1 ) FIG. 3 shows an image obtained by photographing the surface of the concavo-convex layer with a scanning electron microscope and a spatial frequency spectrum.
＜散乱光量＞
各光学素子の凹凸層側の表面に対して、図２に示すように、Ｘｅランプ光源１１から射出された光を開口径３ｍｍのアイリス１２で絞り、ｆ＝１００ｍｍの集光レンズ１３で試料Ｓに入射角４５°で集光する。焦点距離ｆ＝８５ｍｍ、Ｆ値４．０のレンズ（富士フイルム社製）を装着したデジタルスチルカメラＦｉｎｅｐｉｘＳ３ ｐｒｏ（富士フイルム社製）にてＩＳＯ感度２００、シャッタースピード１／２ｓｅｃで試料表面を撮影した。１２８×１２８ピクセルの集光領域のピクセル値の平均値を散乱光量とした。
結果を下記表４に示す。また、実施例１（ピーク：１４μｍ-1）、実施例２（ピーク：１０μｍ-1）、比較例１（ピーク：５μｍ-1）および比較例２（ピーク：７μｍ-1）で作製し光学素子の空間周波数ピークと散乱光量との関係を図４に示す。
<Amount of scattered light>
As shown in FIG. 2, the light emitted from the Xe lamp light source 11 is stopped by an iris 12 having an aperture diameter of 3 mm and the sample S is collected by a condenser lens 13 having f = 100 mm. Is condensed at an incident angle of 45 °. The sample surface was photographed with a digital still camera Finepix S3 pro (manufactured by Fujifilm) equipped with a lens having a focal length f = 85 mm and an F value of 4.0 (manufactured by Fujifilm) at an ISO sensitivity of 200 and a shutter speed of 1/2 sec. . The average value of the pixel values of the 128 × 128 pixel condensing region was defined as the amount of scattered light.
The results are shown in Table 4 below. Further, optical elements manufactured in Example 1 (peak: 14 μm −1 ), Example 2 (peak: 10 μm −1 ), Comparative Example 1 (peak: 5 μm −1 ), and Comparative Example 2 (peak: 7 μm −1 ) The relationship between the spatial frequency peak and the amount of scattered light is shown in FIG.
＜反射率＞
各光学素子の凹凸層側の表面の反射率を、反射分光膜厚計ＦＥ−３０００（大塚電子社製、対物レンズ倍率２０倍）を用いて測定した。なお、対物レンズの倍率２０倍、測定波長は２３０〜８００ｎｍとした。
測定波長２３０〜８００ｎｍのうち、４３０〜６６０ｎｍにおける反射率の平均値（平均反射率）を下記表４に示す。また、実施例１〜４で作製した光学素子の反射率の波長依存性を示すグラフをそれぞれ図５〜図８に示す。
<Reflectance>
The reflectance of the surface on the uneven layer side of each optical element was measured using a reflection spectral film thickness meter FE-3000 (manufactured by Otsuka Electronics Co., Ltd., objective lens magnification 20 times). The objective lens magnification was 20 times and the measurement wavelength was 230 to 800 nm.
Table 4 below shows the average reflectance (average reflectance) at 430 to 660 nm among the measurement wavelengths of 230 to 800 nm. Moreover, the graph which shows the wavelength dependence of the reflectance of the optical element produced in Examples 1-4 is shown in FIGS. 5-8, respectively.
＜拡散反射率＞
図１１に示すように、各光学素子の凹凸層側の表面（試料）に対して、８°方向からコリメートした白色光を入射し、積分球の出力ポートからバンドルファイバによりマルチチャンネルアナライザＣ７４７３（浜松ホトニクス）により分光測定した。
ここで、正反射光を積分球の内壁でブロックしたときの値を拡散反射率および鏡面反射率の和とし、正反射光を積分球の外部に逃がしたときの値を拡散反射率として測定した。
本測定方法で得られた拡散反射率および鏡面反射率の和の測定値を、分光光度計Ｕ−４０００を用いて測定したＳ−ＬＡＨ５５Ｖガラス基板（オハラ社）の反射率で校正することで試料の拡散反射率を測定した。
結果を下記表４に示す。また、実施例１および実施例２で作製した光学素子ならびにガラス基板の拡散反射率の波長依存性を示すグラフを図１０に示す。
<Diffuse reflectance>
As shown in FIG. 11, white light collimated from the direction of 8 ° is incident on the surface (sample) on the uneven layer side of each optical element, and a multi-channel analyzer C7473 (Hamamatsu) is output from the output port of the integrating sphere by a bundle fiber. (Photonics).
Here, the value when the regular reflected light is blocked by the inner wall of the integrating sphere is the sum of the diffuse reflectance and the specular reflectance, and the value when the regular reflected light escapes to the outside of the integrating sphere is measured as the diffuse reflectance. .
By calibrating the measured value of the sum of diffuse reflectance and specular reflectance obtained by this measurement method with the reflectance of the S-LAH55V glass substrate (Ohara) measured using a spectrophotometer U-4000, the sample The diffuse reflectance of was measured.
The results are shown in Table 4 below. Moreover, the graph which shows the wavelength dependence of the optical element produced in Example 1 and Example 2 and the diffuse reflectance of a glass substrate is shown in FIG.
上述した結果、特に、表４および図３および図４に示す結果から、比較例１および２で作製した光学素子は、いずれも凹凸層の空間周波数のピーク値が９μｍ-1以下となり、散乱光の発生が十分に抑制できていないことが分かった。
これに対し、アルミナの水和物（ベーマイト）を主成分とする凹凸層の空間周波数のピーク値が９μｍ-1よりも大きい光学素子は、いずれも散乱光量が少なく、反射率および拡散反射率が低いため、良好な反射防止性能を維持し、散乱光の発生を抑制できることが分かった（実施例１〜４）。
From the results described above, in particular, from the results shown in Table 4 and FIGS. 3 and 4, the optical elements produced in Comparative Examples 1 and 2 both have a peak value of the spatial frequency of the uneven layer of 9 μm −1 or less, and the scattered light It turned out that generation | occurrence | production of is not fully suppressed.
On the other hand, any optical element having a spatial frequency peak value greater than 9 μm −1 of the concavo-convex layer mainly composed of alumina hydrate (boehmite) has a small amount of scattered light, and has a low reflectance and diffuse reflectance. Since it was low, it turned out that favorable antireflection performance is maintained and generation | occurrence | production of scattered light can be suppressed (Examples 1-4).
１ 光学素子
２ 透明基材
３ 反射防止膜
４ 凹凸層
５ 中間層
１１ Ｘｅランプ光源
１２ アイリス
１３ 集光レンズ
１５ デジタルスチルカメラ
Ｓ 試料
DESCRIPTION OF SYMBOLS 1 Optical element 2 Transparent base material 3 Antireflection film 4 Concavity and convexity layer 5 Intermediate layer 11 Xe lamp light source 12 Iris 13 Condensing lens 15 Digital still camera S Sample
Claims (9)
前記反射防止膜が、アルミナの水和物を主成分とする透明な凹凸層を有し、
前記凹凸層の空間周波数のピーク値が、１４μｍ−１以上であり、
前記凹凸層の空間周波数のピーク値は、前記凹凸層の走査型電子顕微鏡画像を二次元フーリエ変換し、得られる二次元の空間周波数強度スペクトルを方位角方向に積算して算出される空間周波数の大きさに対する強度スペクトルのピーク値である、光学素子。 An optical element having a transparent substrate and an antireflection film,
The antireflection film has a transparent uneven layer mainly composed of alumina hydrate,
The peak value of the spatial frequency of the uneven layer is 14 μm −1 or more,
The peak value of the spatial frequency of the concavo-convex layer is the spatial frequency calculated by two-dimensional Fourier transform of the scanning electron microscope image of the concavo-convex layer and integrating the obtained two-dimensional spatial frequency intensity spectrum in the azimuth direction. An optical element that is a peak value of an intensity spectrum with respect to a size.
前記中間層が、前記透明基材の屈折率よりも低い屈折率を有する低屈折率層と、前記透明基材の屈折率よりも高い屈折率を有する高屈折率層とを、前記透明基材側からこの順に有する、請求項１〜３のいずれか１項に記載の光学素子。 The antireflection film further comprises an intermediate layer between the transparent substrate and the uneven layer,
The intermediate layer includes a low refractive index layer having a refractive index lower than that of the transparent substrate, and a high refractive index layer having a refractive index higher than the refractive index of the transparent substrate. The optical element according to claim 1, which is provided in this order from the side.
前記中間層が、前記透明基材の屈折率よりも高い屈折率を有する高屈折率層と、前記透明基材の屈折率よりも低い屈折率を有する低屈折率層とを、前記透明基材側からこの順に有する、請求項１〜３のいずれか１項に記載の光学素子。 The antireflection film further comprises an intermediate layer between the transparent substrate and the uneven layer,
The intermediate layer includes a high refractive index layer having a refractive index higher than that of the transparent substrate, and a low refractive index layer having a refractive index lower than that of the transparent substrate. The optical element according to claim 1, which is provided in this order from the side.
透明基材上に、厚みが１００ｎｍ未満の窒素を含有するアルミニウム膜を形成する膜形成工程と、
前記窒素を含有するアルミニウム膜に温水処理を施し、アルミナの水和物を主成分とする凹凸層を形成する温水処理工程とを有し、前記窒素を含有するアルミニウム膜が透明である、光学素子の製造方法。 A method for producing an optical element for producing the optical element according to claim 1,
A film forming step of forming an aluminum film containing nitrogen having a thickness of less than 100 nm on a transparent substrate;
An optical element comprising: a hot water treatment step of subjecting the aluminum film containing nitrogen to a hot water treatment to form a concavo-convex layer mainly composed of an alumina hydrate, wherein the aluminum film containing nitrogen is transparent Manufacturing method.
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