JP2011221465A - Antireflection film and optical member having the same - Google Patents
Antireflection film and optical member having the same Download PDFInfo
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本発明は反射防止膜、及びこれを有する光学部材に関し、詳しくは耐久性に優れ製造ごとの反射防止性能の変動が小さな反射防止膜、及びこの反射防止膜を有する光学部材に関する。 The present invention relates to an antireflection film and an optical member having the antireflection film, and more particularly relates to an antireflection film having excellent durability and a small variation in antireflection performance for each production, and an optical member having the antireflection film.
写真用カメラや放送用カメラ等に広く用いられている高性能な単焦点レンズやズームレンズは、多数枚(10〜40枚)からなるレンズ構成を有している。これらレンズの表面には、基板の屈折率と異なる大小の屈折率を有する誘電体膜を組み合わせ、各誘電体膜の光学膜厚を中心波長λに対して1/2λや1/4λに設定し、干渉効果を利用した多層膜による反射防止処理が施されている。 High-performance single focus lenses and zoom lenses widely used in photographic cameras, broadcast cameras, and the like have a lens configuration composed of a large number (10 to 40). The surface of these lenses is combined with a dielectric film having a refractive index different from the refractive index of the substrate, and the optical film thickness of each dielectric film is set to 1 / 2λ or 1 / 4λ with respect to the center wavelength λ. The antireflection treatment by the multilayer film using the interference effect is performed.
例えば、光学ガラスBSC7(nd=1.516)基板に、基板側から順に物理膜厚34 nmのZrO2(nd=2.05)層、物理膜厚27 nmのMgF2(nd=1.38)層、物理膜厚43 nmのZrO2(nd=2.05)層、及び物理膜厚103 nmのMgF2(nd=1.38)層を形成した4層構成の反射防止膜は、図16に示すような反射防止特性を有し、波長400〜700 nmの中心波長付近での最大反射率は0.6%近くに達する。 For example, on an optical glass BSC7 (nd = 1.516) substrate, a ZrO2 (nd = 2.05) layer with a physical film thickness of 34 nm, an MgF2 (nd = 1.38) layer with a physical film thickness of 27 nm, and a physical film thickness of 43 nm in order from the substrate side The four-layer antireflection film in which the ZrO2 (nd = 2.05) layer and the MgF2 (nd = 1.38) layer having a physical film thickness of 103 nm have antireflection characteristics as shown in FIG. The maximum reflectivity near the central wavelength of ~ 700 nm reaches close to 0.6%.
このような反射率が0.6%程度の反射防止膜を20枚のレンズからなるレンズ群に施した場合、レンズの面数は40面であるからその透過率は79%となり、21%分の反射損失が生じてしまう。しかも、その反射光が多重反射を繰り返すことによりフレア、ゴースト等が発生し、光学特性が著しく劣化し撮影画像に大きな弊害を引起す。このため、可視光(400〜700 nm)の波長域で最大反射率0.2%程度を達成すべく検討が進められてきた。 When such an antireflection film with a reflectance of about 0.6% is applied to a lens group consisting of 20 lenses, the number of lens surfaces is 40, so the transmittance is 79%, reflecting 21%. Loss will occur. Moreover, flare, ghost, and the like are generated by the multiple reflection of the reflected light, and the optical characteristics are remarkably deteriorated, causing a great adverse effect on the photographed image. For this reason, studies have been conducted to achieve a maximum reflectance of about 0.2% in the visible light (400 to 700 nm) wavelength region.
特開2001-100002号(特許文献1)は、表面から順にMgF2層、ZrO2/TiO2層、Al2O3層、SiO2層、ZrO2/TiO2層、SiO2層、ZrO2/TiO2層、SiO2層、ZrO2/TiO2層及びAl2O3層からなる10層構造を有し、可視域の波長帯域(270 nm)において最大反射率が設計値0.1%以下の反射防止膜を開示しており、製造誤差を加味しても0.2%以下の反射率特性が確保できると記載している。しかしながら、特開2001-100002号に記載の反射防止膜は、400〜700 nmの可視波長域での最大反射率が0.2%を越えてしまうことがある上に、光学膜厚が非常に薄い層(例えば、実施例1の第3層及び第6層、実施例2の第2層、第3層及び第6層等)を有しているため、これらの薄い層の膜厚が変動することにより、製品ごとの反射防止特性の変動が大きいという問題がある。 Japanese Patent Application Laid-Open No. 2001-100002 (Patent Document 1) discloses an MgF 2 layer, ZrO 2 / TiO 2 layer, Al 2 O 3 layer, SiO 2 layer, ZrO 2 / TiO 2 layer, SiO 2 layer, ZrO 2 in order from the surface. / TiO 2 layer, SiO 2 layer, ZrO 2 / TiO 2 layer and 10 layer structure consisting of Al 2 O 3 layer, maximum reflectivity is less than 0.1% of design value in visible wavelength band (270 nm) An antireflection film is disclosed, and it is described that a reflectance characteristic of 0.2% or less can be secured even if manufacturing errors are taken into account. However, the antireflection film described in JP-A-2001-100002 is a layer having a very thin optical film thickness in addition to the maximum reflectance exceeding 400% in the visible wavelength region of 400 to 700 nm. (For example, the third layer and the sixth layer in Example 1, the second layer in Example 2, the third layer, the sixth layer, and the like), and the film thickness of these thin layers varies. Therefore, there is a problem that the variation of the antireflection characteristic for each product is large.
特開2002-107506号(特許文献2)は、表面から順にMgF2層、ZrO2/TiO2層、SiO2層、Al2O3層、ZrO2/TiO2層、SiO2層、ZrO2/TiO2層、SiO2層、ZrO2/TiO2層及びAl2O3層からなる10層構造を有し、実施例2においては可視域の波長帯域(300 nm)において最大反射率が設計値0.1%以下の反射防止膜を開示しており、製造誤差を加味しても0.2%以下の反射率特性が確保できると記載している。しかしながら、特開2002-107506号に記載の反射防止膜も、光学膜厚が非常に薄い層(例えば、実施例1の第1層、第2層及び第4層等)を有しており、これらの薄い層の膜厚が変動することにより、反射特性が大きな影響を受けるため、製品ごとの反射防止特性の変動が大きくいという問題があり、実際には400〜700 nmの波長域での最大反射率が0.2%を越えないように膜厚精度を保つのは容易なことではない。 Japanese Patent Application Laid-Open No. 2002-107506 (Patent Document 2) discloses an MgF 2 layer, ZrO 2 / TiO 2 layer, SiO 2 layer, Al 2 O 3 layer, ZrO 2 / TiO 2 layer, SiO 2 layer, ZrO 2 in order from the surface. / TiO 2 layer, SiO 2 layer, ZrO 2 / TiO 2 layer, and 10 layer structure consisting of Al 2 O 3 layer. In Example 2, the maximum reflectance is designed in the visible wavelength band (300 nm). An antireflection film having a value of 0.1% or less is disclosed, and it is stated that a reflectance characteristic of 0.2% or less can be secured even if manufacturing errors are taken into account. However, the antireflection film described in JP-A-2002-107506 also has a very thin optical film thickness (for example, the first layer, the second layer, and the fourth layer in Example 1). Since the reflection characteristics are greatly affected by fluctuations in the thickness of these thin layers, there is a problem that the antireflection characteristics vary greatly from product to product. Actually, in the wavelength range of 400 to 700 nm It is not easy to maintain film thickness accuracy so that the maximum reflectance does not exceed 0.2%.
特開2007-213021号(特許文献3)は、光学基板上に設けられた10層からなる多層膜であって、第1層、第4層及び第9層が1.35〜1.50の屈折率を有する低屈折率材料により構成され、第3層、第5層、第7層及び第10層が1.55〜1.85の屈折率を有する中間屈折率材料により構成され、第2層、第6層及び第8層が1.70〜2.50の高屈折率材料により構成された反射防止膜を開示しており、波長400〜700 nmで最大反射率が0.05〜0.15%程度の反射防止特性が得られると記載している。しかしながら、特開2007-213021号に記載の反射防止膜は、光学膜厚が非常に薄い層(例えば、実施例1-1の第7層等)を有しており、これらの薄い層の膜厚が変動することにより、反射特性が大きな影響を受けるため、製品ごとの反射防止特性の変動が大きくなるという問題があり、製造誤差を加味すると400〜700 nmの波長域での最大反射率が0.2%を越えてしまうことがある。 Japanese Patent Laid-Open No. 2007-213021 (Patent Document 3) is a multilayer film composed of 10 layers provided on an optical substrate, and the first layer, the fourth layer, and the ninth layer have a refractive index of 1.35 to 1.50. The third layer, the fifth layer, the seventh layer, and the tenth layer are made of an intermediate refractive index material having a refractive index of 1.55 to 1.85, and the second layer, the sixth layer, and the eighth layer are made of a low refractive index material. Discloses an antireflection film composed of a high refractive index material having a layer of 1.70 to 2.50, and describes that an antireflection characteristic having a maximum reflectance of about 0.05 to 0.15% at a wavelength of 400 to 700 nm can be obtained. . However, the antireflection film described in Japanese Patent Application Laid-Open No. 2007-213021 has a layer with a very thin optical film thickness (for example, the seventh layer of Example 1-1). Since the reflection characteristics are greatly affected by fluctuations in thickness, there is a problem that fluctuations in the antireflection characteristics of each product become large. When manufacturing errors are taken into account, the maximum reflectance in the wavelength range of 400 to 700 nm is increased. May exceed 0.2%.
従って、本発明の目的は、十分な耐久性を有し、400〜700 nmの波長域で製造ばらつきを考慮しても最大反射率が0.2%程度の反射防止特性を有し、分光反射特性の製造安定性に優れた反射防止膜を提供することである。 Therefore, the object of the present invention is to have sufficient durability, and have antireflection characteristics with a maximum reflectance of about 0.2% even if manufacturing variations are considered in the wavelength range of 400 to 700 nm, and spectral reflection characteristics. An object of the present invention is to provide an antireflection film excellent in production stability.
上記課題に鑑み鋭意研究の結果、本発明者らは、基板上に、精度良く膜厚を制御できる厚さである100〜150 nmの光学膜厚の層を8層積層して反射防止膜を構成することにより、製造での膜厚変動が反射防止特性へ与える影響がきわめて小さくなり、400〜700 nmの波長域で製造ばらつきを考慮しても最大反射率が0.2%程度の反射防止特性を有する反射防止膜が得られることを見出し、本発明に想到した。 As a result of diligent research in view of the above problems, the present inventors have formed an antireflection film by laminating eight layers having an optical film thickness of 100 to 150 nm, which is a thickness capable of accurately controlling the film thickness, on a substrate. By configuring, the influence of film thickness variation during manufacturing on the antireflection characteristics is extremely small, and even when manufacturing variations are considered in the wavelength range of 400 to 700 nm, antireflection characteristics with a maximum reflectance of about 0.2% are achieved. The present inventors have found that an antireflection film having the same can be obtained, and have arrived at the present invention.
即ち、本発明の反射防止膜は、屈折率1.42〜2.12の基板面上に第1層〜第8層の膜を順に積層してなる反射防止膜であって、前記第1層の屈折率が1.60〜2.20、前記第2層の屈折率が2.10〜2.30、前記第3層の屈折率が1.80〜2.20、前記第4層の屈折率が1.42〜1.52、前記第5層の屈折率が1.45〜1.65、前記第6層の屈折率が2.10〜2.30、前記第7層の屈折率が2.10〜2.30、及び前記第8層の屈折率が1.37〜1.42であり、各層の光学膜厚がそれぞれ独立に100〜150 nmであることを特徴とする。 That is, the antireflection film of the present invention is an antireflection film obtained by sequentially laminating a first layer to an eighth layer on a substrate surface having a refractive index of 1.42 to 2.12, and the refractive index of the first layer is 1.60 to 2.20, the second layer has a refractive index of 2.10 to 2.30, the third layer has a refractive index of 1.80 to 2.20, the fourth layer has a refractive index of 1.42 to 1.52, and the fifth layer has a refractive index of 1.45 to 1.65, the refractive index of the sixth layer is 2.10 to 2.30, the refractive index of the seventh layer is 2.10 to 2.30, and the refractive index of the eighth layer is 1.37 to 1.42, and the optical film thickness of each layer is independently 100 to 150 nm.
前記第1層〜第7層までの各層はそれぞれTiO2、Nb2O5、Ta2O5、CeO2、ZrO2、HfO2、SnO2、In2O3、ZnO、La2O3、Sb2O3、Al2O3及びSiO2からなる群から選ばれた少なくとも1種からなる膜であり、前記第第8層がMgF2からなる膜であるのが好ましい。 The first to seventh layers are TiO 2 , Nb 2 O 5 , Ta 2 O 5 , CeO 2 , ZrO 2 , HfO 2 , SnO 2 , In 2 O 3 , ZnO, La 2 O 3 , respectively. Preferably, the film is made of at least one selected from the group consisting of Sb 2 O 3 , Al 2 O 3 and SiO 2 , and the eighth layer is a film made of MgF 2 .
前記第1層〜7層までの各層がそれぞれTiO2、Nb2O5、Ta2O5、CeO2、ZrO2、HfO2、SnO2、In2O3、ZnO、La2O3及びSb2O3からなる群から選ばれた1種の高屈折率材料からなる膜、Al2O3又はSiO2の中屈折率材料からなる膜、又は前記高屈折率材料と前記中屈折率材料との混合膜であるのが好ましい。 The first to seventh layers are TiO 2 , Nb 2 O 5 , Ta 2 O 5 , CeO 2 , ZrO 2 , HfO 2 , SnO 2 , In 2 O 3 , ZnO, La 2 O 3 and Sb, respectively. A film made of one kind of high refractive index material selected from the group consisting of 2 O 3, a film made of medium refractive index material of Al 2 O 3 or SiO 2 , or the high refractive index material and the medium refractive index material; The mixed film is preferably used.
400〜700 nmの波長域において反射率0.2%以下の分光反射特性を有するのが好ましい。 It is preferable to have a spectral reflection characteristic with a reflectance of 0.2% or less in a wavelength range of 400 to 700 nm.
前記第1層〜第8層の光学膜厚は実質的に同じであるのが好ましい。 The optical film thicknesses of the first layer to the eighth layer are preferably substantially the same.
本発明の光学部材は、前記反射防止膜を有することを特徴とする。 The optical member of the present invention has the antireflection film.
本発明の反射防止膜は、各層を所定の屈折率に設定することにより、各層を100〜150 nmの範囲の光学膜厚で設計することが可能であるため、特別に薄い層がなく、製造時の成膜精度を高めなくても安定した分光反射特性が得られる。このため、テレビカメラ、ビデオカメラ、デジタルカメラ、車載カメラ、顕微鏡、望遠鏡等に使用される光学素子の反射防止膜としてきわめて好適である。 The antireflection film of the present invention can be designed with an optical film thickness in the range of 100 to 150 nm by setting each layer to a predetermined refractive index. Stable spectral reflection characteristics can be obtained without increasing the accuracy of film formation. Therefore, it is extremely suitable as an antireflection film for optical elements used in TV cameras, video cameras, digital cameras, in-vehicle cameras, microscopes, telescopes, and the like.
[1]反射防止膜
本発明の反射防止膜1は、図1に示すように、屈折率1.42〜2.12の基板2上に、前記基板2側から順に第1層〜第8層の膜を順に積層してなり、前記第1層の屈折率が1.60〜2.20、前記第2層の屈折率が2.10〜2.30、前記第3層の屈折率が1.80〜2.20、前記第4層の屈折率が1.42〜1.52、前記第5層の屈折率が1.45〜1.65、前記第6層の屈折率が2.10〜2.30、前記第7層の屈折率が2.10〜2.30、及び前記第8層の屈折率が1.37〜1.42であり、各層の光学膜厚がそれぞれ独立に100〜150 nmである。なお、本願において屈折率は、特に断りのない限り550 nmの波長における値である。
[1] Antireflection film As shown in FIG. 1, the
前記第1層〜第7層までの各層はそれぞれTiO2、Nb2O5、Ta2O5、CeO2、ZrO2、HfO2、SnO2、In2O3、ZnO、La2O3、Sb2O3、Al2O3及びSiO2からなる群から選ばれた少なくとも1種からなる膜であるのが好ましい。これらの材料を単独で使用するか、2種以上を混合して使用することにより、1.42〜2.30の範囲で屈折率を調節した膜を形成することが可能である。特にTiO2、Nb2O5、Ta2O5、CeO2、ZrO2、HfO2、SnO2、In2O3、ZnO、La2O3及びSb2O3からなる群から選ばれた1種の高屈折率材料、並びにAl2O3又はSiO2の中屈折率材料をそれぞれ単独、又は混合して使用するのが好ましい。 The first to seventh layers are TiO 2 , Nb 2 O 5 , Ta 2 O 5 , CeO 2 , ZrO 2 , HfO 2 , SnO 2 , In 2 O 3 , ZnO, La 2 O 3 , respectively. A film made of at least one selected from the group consisting of Sb 2 O 3 , Al 2 O 3 and SiO 2 is preferred. By using these materials alone or in a mixture of two or more, it is possible to form a film having a refractive index adjusted in the range of 1.42 to 2.30. 1 selected from the group consisting of TiO 2 , Nb 2 O 5 , Ta 2 O 5 , CeO 2 , ZrO 2 , HfO 2 , SnO 2 , In 2 O 3 , ZnO, La 2 O 3 and Sb 2 O 3 It is preferable to use a high refractive index material of a kind and a medium refractive index material of Al 2 O 3 or SiO 2 singly or in combination.
前記第8層は低屈折率層であり、MgF2からなる膜であるのが好ましい。 The eighth layer is a low refractive index layer, and is preferably a film made of MgF 2 .
前記第1層の屈折率は1.605〜2.195、前記第2層の屈折率は2.105〜2.295、前記第3層の屈折率は1.805〜2.195、前記第4層の屈折率は1.425〜1.515、前記第5層の屈折率は1.455〜1.645、前記第6層の屈折率は2.105〜2.295、前記第7層の屈折率は2.105〜2.295、及び前記第8層の屈折率は1.375〜1.415であるのが好ましい。 The refractive index of the first layer is 1.605 to 2.195, the refractive index of the second layer is 2.105 to 2.295, the refractive index of the third layer is 1.805 to 2.195, the refractive index of the fourth layer is 1.425 to 1.515, The refractive index of the five layers is 1.455 to 1.645, the refractive index of the sixth layer is 2.105 to 2.295, the refractive index of the seventh layer is 2.105 to 2.295, and the refractive index of the eighth layer is 1.375 to 1.415. preferable.
各層の光学膜厚をそれぞれ独立に100〜150 nmとすることにより、膜形成時に膜厚を精度良く制御することが可能である。その結果、製造時の光学膜厚の変動が少なくなり、反射防止性能の変動の少ない反射防止膜を得ることができる。各層の光学膜厚はそれぞれ独立に105〜145 nmであるのが好ましい。 By setting the optical film thickness of each layer independently to 100 to 150 nm, the film thickness can be accurately controlled during film formation. As a result, the variation in the optical film thickness at the time of manufacture is reduced, and an antireflection film with little variation in the antireflection performance can be obtained. The optical film thickness of each layer is preferably 105 to 145 nm independently.
基板2は、屈折率が1.42〜2.12であり、好ましくは1.44〜2.10である。屈折率がこのような値の基板2を用いて前記反射防止膜1を形成することにより、波長領域400〜700 nmにおいて優れた反射防止性能を得ることができる。
The substrate 2 has a refractive index of 1.42 to 2.12, preferably 1.44 to 2.10. By forming the
基板2の形状は特に限定されず、板、レンズ、プリズム等の光学部材の基板となるような形状であれば良い。基板2は石英ガラス、蛍石、光学ガラス(BaSF2、SF5、SK16、LaSF01、LaSF09、LaSF016、BK7、FK5、PK1、LaF2、LaF3、LaSK01、LAK7、LAK14等)、光学結晶(フッ化リチウム、フッ化バリウム、フッ化マグネシウム、LBO、CLBO、BBO、KTP、KDP、DKDP、ADP等)、セラミックス(ルミセラ(登録商標)等)等からなるのが好ましい。 The shape of the board | substrate 2 is not specifically limited, What is necessary is just a shape used as a board | substrate of optical members, such as a board, a lens, and a prism. Substrate 2 is quartz glass, fluorite, optical glass (BaSF2, SF5, SK16, LaSF01, LaSF09, LaSF016, BK7, FK5, PK1, LaF2, LaF3, LaSK01, LAK7, LAK14, etc.), optical crystal (lithium fluoride, fluorine It is preferably made of barium fluoride, magnesium fluoride, LBO, CLBO, BBO, KTP, KDP, DKDP, ADP, etc.), ceramics (Lumicera (registered trademark), etc.) and the like.
[2]製造方法
第1層〜第7層は反応性スパッタリング法、イオンビームアシスト蒸着法、反応性イオンプレーティング法のいずれかの方法で成膜するのが好ましく、中でも反応性スパッタリング法が最も好ましい。また必要に応じてこれらの方法を組み合わせて用いても良い。これらの方法は膜厚制御性が良い成膜法なので、製造ごとの膜厚の変動が小さくなり、波長400〜700 nmで製造ばらつきを考慮しても最大反射率が0.2%以下の反射防止特性を有する反射防止膜が得られる。また、これらの方法で形成される膜は従来の真空蒸着法に比べて高い硬度を有するので耐久性に優れた反射防止膜が得られる。第8層は真空蒸着法で形成するのが好ましい。
[2] Manufacturing method The first to seventh layers are preferably formed by a reactive sputtering method, an ion beam assisted vapor deposition method, or a reactive ion plating method, and the reactive sputtering method is the most preferable. preferable. Moreover, you may use combining these methods as needed. Since these methods have good film thickness controllability, the variation in film thickness from manufacturing to manufacturing is small, and the maximum reflectance is 0.2% or less even when manufacturing variations are considered at wavelengths of 400 to 700 nm. An antireflective film having the following is obtained. Moreover, since the film formed by these methods has higher hardness than the conventional vacuum deposition method, an antireflection film excellent in durability can be obtained. The eighth layer is preferably formed by a vacuum evaporation method.
第1層〜第7層の各層は、異なる屈折率を有する2種以上の材料を混合することによってそれぞれ所望の屈折率に調節することができる。例えば反応性スパッタリング法により各層を形成する場合、少なくとも2種以上の異種金属からなる各ターゲットをそれぞれに独立にスパッタリングして形成した複合金属からなる超薄膜に、電気的に中性な酸素ガスの活性種を照射し、複合金属と酸素ガスの活性種とを反応させて複合金属の酸化物に変換することによって所望の屈折率を有する混合膜を形成することができる。超薄膜の形成と、超薄膜の複合金属の酸化物への変換とを順次繰り返すことで、混合膜の厚さの調節が可能である。 Each of the first to seventh layers can be adjusted to a desired refractive index by mixing two or more materials having different refractive indexes. For example, when each layer is formed by a reactive sputtering method, an electrically neutral oxygen gas is applied to an ultrathin film made of a composite metal formed by independently sputtering each target made of at least two kinds of different metals. A mixed film having a desired refractive index can be formed by irradiating active species and reacting the composite metal with the active species of oxygen gas to convert it into an oxide of the composite metal. The thickness of the mixed film can be adjusted by sequentially repeating the formation of the ultrathin film and the conversion of the ultrathin film into a composite metal oxide.
形成される混合膜の屈折率は、前記2種以上の異種金属からなるターゲットをスパッタリングする際に、ターゲットに印加する電力量を変え各金属のスパッタ量を調節することにより設定することができる。例えば、2種の金属をターゲットとして用いる場合、混合膜の屈折率は前記2種の金属酸化物の各屈折率の間の任意の屈折率に調節することが可能である。各ターゲットへの印加電力量と形成される混合膜の屈折率との関係は、予備実験により検量線を作成することで求めておくのが好ましい。 The refractive index of the formed mixed film can be set by changing the amount of power applied to the target and adjusting the sputtering amount of each metal when sputtering the target made of two or more different kinds of metals. For example, when two types of metals are used as a target, the refractive index of the mixed film can be adjusted to an arbitrary refractive index between the refractive indexes of the two types of metal oxides. The relationship between the amount of electric power applied to each target and the refractive index of the formed mixed film is preferably determined by preparing a calibration curve through preliminary experiments.
[3]光学部材
本発明の反射防止膜を前述の基板に施すことにより、400〜700 nmの可視光帯域において、製造ばらつきを考慮しても最大反射率が0.2%以下の反射防止効果を有する光学部品が得られる。本発明の光学部品は、テレビカメラ、ビデオカメラ、デジタルカメラ、車載カメラ、顕微鏡、望遠鏡等の光学機器に搭載されるレンズ、プリズム、回折素子等に好適である。特に本発明の反射防止膜は耐久性に優れているので、カメラの対物レンズや接眼レンズ等の手に触れやすい部分のレンズに好適である。
[3] Optical member By applying the antireflection film of the present invention to the above-mentioned substrate, in the visible light band of 400 to 700 nm, the antireflection effect has a maximum reflectance of 0.2% or less even when manufacturing variations are taken into consideration. An optical component is obtained. The optical component of the present invention is suitable for a lens, a prism, a diffraction element, and the like mounted on an optical device such as a television camera, a video camera, a digital camera, an in-vehicle camera, a microscope, and a telescope. In particular, since the antireflection film of the present invention is excellent in durability, it is suitable for a lens in a part that is easily touched by a hand such as an objective lens or an eyepiece lens of a camera.
以下実施例により本発明を具体的に説明するが、本発明はこれらに限定されるものではない。 EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
実施例1
本発明の反射防止膜の例として、屈折率1.42の基板上に各層の光学膜厚が全て125.0 nmとなるように第1層〜第8層まで順に積層してなる反射防止膜を設計し、光学薄膜計算シミュレーションにより400〜700 nmの波長域で反射率が最も小さくなるように各層の屈折率を最適化した。最適化された屈折率を表1に示し、その分光反射率の計算結果を図2に示す。
Example 1
As an example of the antireflection film of the present invention, an antireflection film is designed by laminating the first layer to the eighth layer in order so that the optical film thickness of each layer is 125.0 nm on a substrate having a refractive index of 1.42. The refractive index of each layer was optimized by the optical thin film calculation simulation so that the reflectance was minimized in the wavelength range of 400 to 700 nm. Table 1 shows the optimized refractive index, and Fig. 2 shows the calculation result of the spectral reflectance.
実施例2〜8
基板の屈折率を表2〜8に示すように1.52〜2.12の間で変更した以外は実施例1と同様にして、実施例2〜8の反射防止膜を設計し、各層の屈折率を最適化した。最適化された屈折率をそれぞれ表2〜8に示し、その分光反射率の計算結果をそれぞれ図3〜9に示す。
Examples 2-8
The antireflective film of Examples 2-8 is designed in the same manner as in Example 1 except that the refractive index of the substrate is changed between 1.52 and 2.12 as shown in Tables 2-8, and the refractive index of each layer is optimized. Turned into. The optimized refractive indexes are shown in Tables 2 to 8, respectively, and the calculation results of the spectral reflectances are shown in FIGS.
実施例1〜8の結果から、屈折率1.42〜2.12の基板に8層積層してなる反射防止膜は、各層の光学膜厚を全て一定の厚さ(125.0 nm)に設計した場合であっても、各層の屈折率を最適化することにより、400〜700 nmの波長域で最大反射率が0.1%程度の優れた反射防止効果を発揮することが分かる。 From the results of Examples 1 to 8, the antireflection film formed by laminating eight layers on a substrate having a refractive index of 1.42 to 2.12 is a case where the optical film thickness of each layer is designed to be a constant thickness (125.0 nm). However, it can be seen that by optimizing the refractive index of each layer, an excellent antireflection effect with a maximum reflectance of about 0.1% is exhibited in the wavelength region of 400 to 700 nm.
実施例9
BSC7(Nd=1.516)ガラス基板に、実施例1と同様にして第1層〜第8層の反射防止膜を表9に示すように設計した。この反射防止膜の分光反射率の計算結果を図10に示す。
Example 9
As shown in Table 9, the first to eighth antireflection films were designed on a BSC7 (Nd = 1.516) glass substrate in the same manner as in Example 1. FIG. 10 shows the calculation result of the spectral reflectance of this antireflection film.
表9に示す反射防止膜を、Nb2O5(屈折率2.243)、SiO2(屈折率1.480)及びMgF2(屈折率1.38)によって以下のようにして作製した。 The antireflection film shown in Table 9 was produced as follows using Nb 2 O 5 (refractive index 2.243), SiO 2 (refractive index 1.480) and MgF 2 (refractive index 1.38).
第1層、第3層、第5層及び第7層の形成
第1層(屈折率1.765)、第3層(屈折率2.077)、第5層(屈折率1.531)及び第7層(屈折率2.212)は、シンクロン社製RAS-1100Cを用いた反応性スパッタリング法により、屈折率2.243のNb2O5と屈折率1.480のSiO2とからなる混合膜として形成した。金属Nbと金属Siとをターゲットにして、アルゴンガスによるスパッタで1 nm以下の超薄膜を形成した後に、ラジカルガンで発生させた酸素ガスの活性種を照射することにより混合金属を酸化し、Nb2O5とSiO2とからなる混合膜を形成した。このスパッタリングと酸素ガスの活性種の照射とを膜厚が125.0 nmになるまで繰り返した。
Formation of first layer, third layer, fifth layer and seventh layer First layer (refractive index 1.765), third layer (refractive index 2.077), fifth layer (refractive index 1.531) and seventh layer (refractive index) 2.212) was formed as a mixed film of Nb 2 O 5 having a refractive index of 2.243 and SiO 2 having a refractive index of 1.480 by a reactive sputtering method using RAS-1100C manufactured by SYNCHRON. After forming an ultra-thin film of 1 nm or less by sputtering with argon gas using metal Nb and metal Si as targets, the mixed metal is oxidized by irradiating active species of oxygen gas generated by a radical gun, and Nb A mixed film composed of 2 O 5 and SiO 2 was formed. This sputtering and irradiation with active species of oxygen gas were repeated until the film thickness reached 125.0 nm.
第1層、第3層、第5層及び第7層の各混合膜の屈折率は、NbターゲットとSiターゲットとにそれぞれ印加する電力を変えることにより調節した。予備実験により、[(Nbターゲットへの印加電力)/(Nbターゲット+Siターゲットへの印加電力)]と屈折率との間にはほぼ直線関係が得られたため、この関係から各ターゲットの印加電力を調整することによって、屈折率を1.48〜2.24の範囲で任意に設定することができた。スパッタリング条件及び酸素ガスの活性種の発生条件は以下の通りであった。 The refractive indexes of the mixed films of the first layer, the third layer, the fifth layer, and the seventh layer were adjusted by changing the power applied to the Nb target and the Si target, respectively. As a result of preliminary experiments, a linear relationship was obtained between [(applied power to Nb target) / (applied power to Nb target + Si target)] and the refractive index. By adjusting the refractive index, the refractive index could be arbitrarily set in the range of 1.48 to 2.24. The sputtering conditions and the generation conditions of the active species of oxygen gas were as follows.
(a)Nbスパッタリング条件
投入電力:0〜1.6 kw
基板温度:室温
アルゴン導入量:200 sccm
基板ホルダ回転数:100 rpm
超薄膜の厚さ:1 nm以下
(a) Input power for Nb sputtering conditions: 0 to 1.6 kw
Substrate temperature: room temperature Argon introduced: 200 sccm
Substrate holder rotation speed: 100 rpm
Ultrathin film thickness: 1 nm or less
(b)Siスパッタリング条件
投入電力:0〜2.5 kw
基板温度:室温
アルゴン導入量:400 sccm
基板ホルダ回転数:100 rpm
超薄膜の厚さ:1 nm以下
(b) Si sputtering condition input power: 0 to 2.5 kw
Substrate temperature: room temperature Argon introduced: 400 sccm
Substrate holder rotation speed: 100 rpm
Ultrathin film thickness: 1 nm or less
(c)酸素ガスのラジカル条件
投入電力:2.0 kw
酸素導入量:80 sccm
※ なお成膜は、真空度2.0×10-4Paまで排気してから開始した。
(c) Oxygen gas radical condition input power: 2.0 kw
Oxygen introduction amount: 80 sccm
* Film formation was started after evacuating to a vacuum of 2.0 × 10 −4 Pa.
第2層、第4層及び第6層の形成
第2層及び第6層のNb2O5からなる厚さ125.0 nmの単独膜は、Nbターゲットのみを用いて反応性スパッタリング法により形成し、第4層のSiO2からなる厚さ125.0 nmの単独膜は、Siターゲットのみを用いて反応性スパッタリング法により形成した。
Formation of the second layer, the fourth layer, and the sixth layer The single layer 125.0 nm thick made of Nb 2 O 5 of the second layer and the sixth layer is formed by a reactive sputtering method using only an Nb target, The fourth layer of SiO 2 having a thickness of 125.0 nm was formed by a reactive sputtering method using only a Si target.
第8層の形成
第8層のMgF2膜は、昭和真空社製SGC-22SAによる電子ビーム蒸着法を用いて形成した。すなわち、蒸発源ルツボにMgF2の顆粒を充填し、第7層まで形成した基板を250℃に加熱し、真空度2.0×10-3Pa、及び成膜速度約40 nm/minにて厚さ125.0 nmに成膜した。
Formation of Eighth Layer The eighth layer of MgF 2 film was formed by electron beam evaporation using SGC-22SA manufactured by Showa Vacuum. That is, MgF 2 granules are filled in the evaporation source crucible, the substrate formed up to the seventh layer is heated to 250 ° C., and the thickness is set at a vacuum degree of 2.0 × 10 −3 Pa and a film formation rate of about 40 nm / min. A film was formed at 125.0 nm.
この反射防止膜を同じ方法で20回繰り返して作製した。得られた20サンプルの分光反射率の重ね書きを図11に示す。 This antireflection film was produced 20 times by the same method. FIG. 11 shows an overlay of the spectral reflectances of the 20 samples obtained.
比較例1
特開2002-14203を参考にして、BSC7(nd=1.516)ガラス基板に、表10に示すように各層の光学膜厚を最適化したTiO2及びSiO2からなる14層の反射防止膜を設計した。その分光反射率の計算結果を図12に示す。
Comparative Example 1
With reference to JP2002-14203, a 14-layer antireflection film made of TiO 2 and SiO 2 with optimized optical film thickness of each layer as shown in Table 10 is designed on a BSC7 (nd = 1.516) glass substrate. did. FIG. 12 shows the calculation result of the spectral reflectance.
表10に示す反射防止膜を、反応性スパッタリング法により20回繰り返して作製した。得られた20サンプルの分光反射率の重ね書きを図13に示す。 The antireflection film shown in Table 10 was produced 20 times by a reactive sputtering method. FIG. 13 shows an overlay of the spectral reflectances of the 20 samples obtained.
図11及び図13の比較から明らかなように、本発明の実施例9の反射防止膜(図11)は比較例1(図13)に比べて反射防止性能の製造安定性に優れていることが分かる。 As is clear from the comparison between FIGS. 11 and 13, the antireflection film (FIG. 11) of Example 9 of the present invention is superior in manufacturing stability of antireflection performance compared to Comparative Example 1 (FIG. 13). I understand.
実施例10
TAFD30(Nd=1.88)ガラス基板上に、表11に示すように各層の屈折率及び光学膜厚を最適化したNb2O5及びSiO2からなる8層の反射防止膜を設計した。その分光反射率の計算結果を図14に示す。
Example 10
On the TAFD30 (Nd = 1.88) glass substrate, as shown in Table 11, an eight-layer antireflection film composed of Nb 2 O 5 and SiO 2 with the optimized refractive index and optical film thickness of each layer was designed. FIG. 14 shows the calculation result of the spectral reflectance.
表11に示す反射防止膜を、実施例1と同様にして反応性スパッタリング法により20回繰り返して作製した。得られた20サンプルの分光反射率の重ね書きを図15に示す。 The antireflection film shown in Table 11 was produced 20 times by the reactive sputtering method in the same manner as in Example 1. FIG. 15 shows an overlay of the spectral reflectances of the 20 samples obtained.
実施例9と同様、実施例10の反射防止膜(図15)は反射防止性能の製造安定性に優れていることが分かる。
As in Example 9, it can be seen that the antireflection film of Example 10 (FIG. 15) is excellent in manufacturing stability of antireflection performance.
1・・・反射防止膜
2・・・基板
DESCRIPTION OF
Claims (6)
前記第1層の屈折率が1.60〜2.20、前記第2層の屈折率が2.10〜2.30、前記第3層の屈折率が1.80〜2.20、前記第4層の屈折率が1.42〜1.52、前記第5層の屈折率が1.45〜1.65、前記第6層の屈折率が2.10〜2.30、前記第7層の屈折率が2.10〜2.30、及び前記第8層の屈折率が1.37〜1.42であり、各層の光学膜厚がそれぞれ独立に100〜150 nmであることを特徴とする反射防止膜。 An antireflection film comprising a first layer to an eighth layer laminated in order on a substrate surface having a refractive index of 1.42 to 2.12,
The refractive index of the first layer is 1.60 to 2.20, the refractive index of the second layer is 2.10 to 2.30, the refractive index of the third layer is 1.80 to 2.20, the refractive index of the fourth layer is 1.42 to 1.52, Each layer has a refractive index of 5.45 to 1.65, a refractive index of the sixth layer of 2.10 to 2.30, a refractive index of the seventh layer of 2.10 to 2.30, and a refractive index of the eighth layer of 1.37 to 1.42. The optical film thickness of each is independently 100-150 nm, The antireflection film | membrane characterized by the above-mentioned.
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CN113703078A (en) * | 2021-08-31 | 2021-11-26 | 重庆文理学院 | Broadband antireflection film for visible light region and preparation method thereof |
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