JP2014215402A - Optical device - Google Patents

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JP2014215402A
JP2014215402A JP2013091575A JP2013091575A JP2014215402A JP 2014215402 A JP2014215402 A JP 2014215402A JP 2013091575 A JP2013091575 A JP 2013091575A JP 2013091575 A JP2013091575 A JP 2013091575A JP 2014215402 A JP2014215402 A JP 2014215402A
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refractive index
antireflection film
optical device
visible light
layers
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JP6116337B2 (en
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佑一 加茂
Yuichi Kamo
佑一 加茂
大西　学
Manabu Onishi
学 大西
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Daishinku Corp
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Priority to CN201480020905.3A priority patent/CN105122090B/en
Priority to PCT/JP2014/001395 priority patent/WO2014174751A1/en
Priority to TW103110029A priority patent/TWI518356B/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • G02B1/113—Anti-reflection coatings using inorganic layer materials only
    • G02B1/115—Multilayers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B2207/00—Coding scheme for general features or characteristics of optical elements and systems of subclass G02B, but not including elements and systems which would be classified in G02B6/00 and subgroups
    • G02B2207/101—Nanooptics

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Surface Treatment Of Optical Elements (AREA)
  • Laminated Bodies (AREA)
  • Optical Filters (AREA)
  • Surface Treatment Of Glass (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide an optical device capable of effectively preventing occurrence of a white fogging phenomenon even when left under high temperature and high humidity conditions.SOLUTION: The optical device includes an antireflection film 3 for preventing a reflection of a visible light on a surface of an infrared ray absorption glass. The antireflection film is constituted by laminating refractive index layers 3a to 3c having at least two or more layers different in refractive index. Among the refractive index layers having at least two or more layers, at least one or more layers other than the refractive index layer low in refractive index includes AlOor ZrOor mixtures thereof, and an average grain size on an upper surface of the antireflection film is less than 25 nm.

Description

本発明は、赤外線吸収ガラス等の可視光透過性基板の面上に反射防止膜（ＡＲ膜）が形成されてある光学デバイスに関するものである。なお、本明細書で言う屈折率は大気中での屈折率である。   The present invention relates to an optical device in which an antireflection film (AR film) is formed on the surface of a visible light transmissive substrate such as infrared absorbing glass. In addition, the refractive index said in this specification is a refractive index in air | atmosphere.

デジタルカメラ等で使用されるＣＣＤ、ＣＭＯＳなどの撮像素子の分光感度は、可視光の領域から赤外光の領域にわたる。前記可視光透過性基板として、例えば赤外線吸収ガラスを用いたものでは、この撮像素子に入射する光のうち、赤外光を赤外線吸収ガラスにより吸収し、可視光を撮像素子に受光できるようにすることで、撮像画像を人間の視感度に近似させている。そして、この赤外線吸収ガラスなどの可視光透過性基板の表面に反射防止膜を成膜することで、可視光の反射損失を低減し、その透過率を向上させるようにしている。   The spectral sensitivity of an image sensor such as a CCD or CMOS used in a digital camera or the like ranges from the visible light region to the infrared light region. For example, in the case of using an infrared absorbing glass as the visible light transmissive substrate, infrared light is absorbed by the infrared absorbing glass among the light incident on the imaging element so that the visible light can be received by the imaging element. Thus, the captured image is approximated to human visibility. Then, an antireflection film is formed on the surface of a visible light transmissive substrate such as an infrared ray absorbing glass, thereby reducing the reflection loss of visible light and improving the transmittance.

このような可視光透過性基板の表面に反射防止膜を成膜した光学デバイスでは前記した反射防止膜が単層であると、任意の波長以外では反射防止効果が十分ではない。特許文献１には、屈折率が異なる３層からなる反射防止膜の技術も提案され、可視域全体である400nm〜700nm帯域の反射防止を可能としている。   In such an optical device having an antireflection film formed on the surface of a visible light transmissive substrate, if the antireflection film is a single layer, the antireflection effect is not sufficient except for an arbitrary wavelength. Patent Document 1 also proposes a technique of an antireflection film including three layers having different refractive indexes, and enables antireflection in the 400 nm to 700 nm band that is the entire visible range.

特開平５−２１０１号公報JP-A-5-2101

ところで、撮像カメラの使用環境には高温高湿な環境もあり、このような撮像カメラの光学系に組み込まれる光学デバイスは、高温高湿な環境でも、その光学特性が損なわれないことが望ましい。本発明者は、光学デバイスに対して高温高湿環境下で長時間放置する試験を実施したところ、試験前では可視光の透過率が良好な光学デバイスが、試験後では、水分が基板内部に侵入し、基板を溶解させることにより、光を散乱させるため、全体に白く曇ったように見える現象が発生し、可視光の透過率が極端に低下した。そこで、本発明者は、前記白い曇り現象の発生の原因について鋭意究明した結果、本発明を完成できるに至った。   Incidentally, the use environment of the imaging camera includes a high-temperature and high-humidity environment, and it is desirable that the optical characteristics of the optical device incorporated in the optical system of such an imaging camera are not impaired even in a high-temperature and high-humidity environment. The inventor conducted a test in which the optical device was left for a long time in a high-temperature and high-humidity environment. As a result, an optical device having a good visible light transmittance before the test was obtained. By intruding and dissolving the substrate, the light is scattered, so that a phenomenon that looks white and cloudy is generated as a whole, and the transmittance of visible light is extremely lowered. Thus, as a result of earnest investigation on the cause of the occurrence of the white clouding phenomenon, the present inventor has completed the present invention.

すなわち、本発明は、上記に鑑みて為されたものであり、赤外線吸収ガラス等の可視光透過性基板の面上に屈折率が相異なる複数の積層膜からなる反射防止膜を設けた光学デバイスにおいて、高温高湿環境下に長時間放置しても、上記白い曇り現象の発生が防止され、透過性が試験前と同様に維持された、耐候性に優れた光学デバイスを提供することを目的としている。   That is, the present invention has been made in view of the above, and an optical device in which an antireflection film composed of a plurality of laminated films having different refractive indexes is provided on the surface of a visible light transmissive substrate such as infrared absorbing glass. The purpose of the present invention is to provide an optical device with excellent weather resistance in which the occurrence of the above white clouding phenomenon is prevented even when left in a high temperature and high humidity environment for a long time, and the transparency is maintained in the same manner as before the test. It is said.

（１）上記の目的を達成するために、本発明に係る光学デバイスは、可視光透過性基板の少なくとも１つの面上に可視光の反射を防止する反射防止膜を備えた光学デバイスであって、前記反射防止膜が、屈折率が異なる少なくとも２層以上の屈折率層が積層されて構成されていると共に、前記少なくとも２層以上の屈折率層のうち、屈折率が低い屈折率層以外の、少なくとも1層以上に、その材料としてＡｌ２Ｏ３又はＺｒＯ２又はこれらの混合物を少なくとも含み、かつ、前記反射防止膜の上面における粒子の平均粒径が２５ｎｍ未満である、ことを特徴とするものである。 (1) In order to achieve the above object, an optical device according to the present invention is an optical device including an antireflection film for preventing reflection of visible light on at least one surface of a visible light transmissive substrate. The antireflection film is formed by laminating at least two or more refractive index layers having different refractive indexes, and of the at least two or more refractive index layers other than the refractive index layer having a low refractive index. In addition, at least one layer includes at least Al 2 O 3 or ZrO 2 or a mixture thereof, and the average particle diameter of the particles on the upper surface of the antireflection film is less than 25 nm. Is.

前記反射防止膜は、前記可視光透過性基板の片面に設けてもよいし、両面に設けてもよく、いずれの場合も本発明に含む。前記反射防止膜は、その成膜方法に限定されないが、真空蒸着法等の物理蒸着法により形成するのが好ましい。前記反射防止膜の上面における粒子の平均粒径は２５ｎｍ未満であれば、どの平均粒径であってもよく、平均粒径を適宜に選択するとよい。   The antireflection film may be provided on one side or both sides of the visible light transmissive substrate, and both cases are included in the present invention. The antireflection film is not limited to the film formation method, but is preferably formed by a physical vapor deposition method such as a vacuum vapor deposition method. The average particle diameter of the particles on the upper surface of the antireflection film may be any average particle diameter as long as it is less than 25 nm, and the average particle diameter may be appropriately selected.

本発明では、前記反射防止膜の上面における粒子の平均粒径が２５ｎｍ未満であることにより、高温高湿の環境下に長時間放置しても反射防止膜中に水分が容易に浸入することを防止できるようになった結果、白く曇ることが防止されて、可視光の透過性を維持できる。本発明の光学デバイスを、撮像カメラの撮像素子の直前に配置した場合には、良好な撮像画像を長期にわたり維持でき、耐候性に優れた撮像カメラを提供できる。   In the present invention, when the average particle diameter of the particles on the upper surface of the antireflection film is less than 25 nm, moisture can easily enter the antireflection film even if left for a long time in a high temperature and high humidity environment. As a result, it is possible to prevent white cloudiness and maintain visible light permeability. When the optical device of the present invention is disposed immediately before the imaging element of the imaging camera, it is possible to maintain an excellent captured image for a long period of time and provide an imaging camera with excellent weather resistance.

なお、可視光透過性基板は、可視光を透過させることができるものであればよく、特に限定されるものではない。   The visible light transmissive substrate is not particularly limited as long as it can transmit visible light.

（２）本発明の前記（１）において好ましい実施態様は、前記屈折率が異なる少なくとも２層以上の屈折率層が、前記可視光透過性基板の面上に積層されて構成されているとともに、少なくとも可視光透過性基板から数えて第１層目に、その材料としてＡｌ２Ｏ３又はＺｒＯ２又はこれらの混合物を少なくとも含む。 (2) In a preferred embodiment of (1) of the present invention, at least two or more refractive index layers having different refractive indexes are laminated on the surface of the visible light transmissive substrate, At least the first layer counting from the visible light transmissive substrate contains at least Al 2 O 3 or ZrO 2 or a mixture thereof as the material.

この場合、少なくとも可視光透過性基板から数えて第１層目の材料が、Ａｌ２Ｏ３又はＺｒＯ２又はこれらの混合物を少なくとも含むもので構成することで、中屈折率層として、屈折率が１．６〜１．７の範囲にあるＡｌ２Ｏ３、もしくは高屈折率層として、屈折率が２．０〜２．４の範囲にあるＺｒＯ２が形成されるので、多数層からなる反射防止膜の設計が容易に行えるといったメリットがある。結果として、可視光領域全体に反射防止効果をもつ分光特性を得ることができる。しかしながら、少なくとも可視光透過性基板から数えて第１層目の材料が、Ａｌ２Ｏ３又はＺｒＯ２又はこれらの混合物を少なくとも含むものであると、水分が浸入した際に基板を溶解させやすく作用することがあり、従来の問題点がより顕著に生じやすい。これに対して上述の構成と組み合わせることで、反射防止膜中に水分が容易に浸入することを防止できるようになり、白く曇ることが防止され、可視光の透過性を維持できる。 In this case, at least the first layer material counted from the visible light transmissive substrate is composed of at least Al 2 O 3, ZrO 2, or a mixture thereof. Since Al 2 O 3 in the range of 1.6 to 1.7 or ZrO 2 in the range of 2.0 to 2.4 is formed as the high refractive index layer, reflection consisting of multiple layers There is an advantage that the prevention film can be easily designed. As a result, it is possible to obtain spectral characteristics having an antireflection effect over the entire visible light region. However, when the material of the first layer counted at least from the visible light transmissive substrate contains at least Al 2 O 3, ZrO 2, or a mixture thereof, it acts to easily dissolve the substrate when moisture enters. The conventional problems are more likely to occur. On the other hand, by combining with the above-described configuration, it becomes possible to prevent moisture from easily entering the antireflection film, to prevent white fogging, and to maintain visible light permeability.

（３）本発明の前記（１）において好ましい実施態様は、前記可視光透過性基板の材料が、銅イオンを含有するフツリン酸塩系ガラスもしくは、リン酸塩系ガラスである。   (3) In said (1) of this invention, a preferable embodiment is a fluorophosphate glass or a phosphate glass containing copper ions as the material for the visible light transmissive substrate.

この場合、可視光透過性基板の材料が、銅イオンを含有するフツリン酸塩系ガラスもしくは、リン酸塩系ガラスであると、赤外線吸収効果が高い状態で可視光を撮像素子に受光させ、撮像画像を人間の視感度に近似させることができる。また、ゴーストやフレアの原因を低減することができる。しかしながら、可視光透過性基板の材料が、銅イオンを含有するフツリン酸塩系ガラスもしくは、リン酸塩系ガラスであると、水分が浸入した際に溶解することがあり、従来の問題点がより顕著に生じやすい。これに対して上述の構成と組み合わせることで、反射防止膜中に水分が容易に浸入することを防止できるようになり、白く曇ることが防止され、可視光の透過性を維持できる。   In this case, if the material of the visible light transmissive substrate is a fluorophosphate glass or phosphate glass containing copper ions, the visible light is received by the image sensor with a high infrared absorption effect, and imaging is performed. The image can be approximated to human visibility. In addition, the cause of ghost and flare can be reduced. However, if the material of the visible light transmissive substrate is a fluorophosphate glass or phosphate glass containing copper ions, it may be dissolved when moisture enters, and the conventional problems are more Remarkably easy to occur. On the other hand, by combining with the above-described configuration, it becomes possible to prevent moisture from easily entering the antireflection film, to prevent white fogging, and to maintain visible light permeability.

本発明の光学デバイスは、高温高湿の環境下に長時間放置しても白い曇り現象の発生を防止することができるので、初期の光学特性を長期に亘り維持できるという耐候性に優れたものである。   The optical device of the present invention can prevent the occurrence of white clouding even when left in a high temperature and high humidity environment for a long time, and therefore has excellent weather resistance that can maintain the initial optical characteristics over a long period of time. It is.

図１は本発明の実施形態に係る光学デバイスの断面図である。FIG. 1 is a cross-sectional view of an optical device according to an embodiment of the present invention. 図２は前記光学デバイスの波長対反射率特性図である。FIG. 2 is a wavelength vs. reflectance characteristic diagram of the optical device. 図３（ａ）は比較例の表面における粒子状態の模式図、図３（ｂ）は実施形態の表面における粒子状態の模式図である。FIG. 3A is a schematic diagram of the particle state on the surface of the comparative example, and FIG. 3B is a schematic diagram of the particle state on the surface of the embodiment. 図４は本発明の他の実施形態に係る光学デバイスの断面図である。FIG. 4 is a cross-sectional view of an optical device according to another embodiment of the present invention. 図５は本発明のさらに他の実施形態に係る光学デバイスの断面図である。FIG. 5 is a cross-sectional view of an optical device according to still another embodiment of the present invention. 図６は本発明のさらに他の実施形態に係る光学デバイスの断面図である。FIG. 6 is a cross-sectional view of an optical device according to still another embodiment of the present invention. 図７（ａ）は適正温度で作製した光学デバイスにおける反射防止膜の上面における粒子状態を示すＳＥＭ像、図７（ｂ）は過剰温度で作製した光学デバイスにおける反射防止膜の上面における粒子状態を示すＳＥＭ像である。FIG. 7A shows an SEM image showing the particle state on the upper surface of the antireflection film in the optical device manufactured at an appropriate temperature, and FIG. 7B shows the particle state on the upper surface of the antireflection film in the optical device manufactured at an excessive temperature. It is a SEM image shown. 図８（ａ）は比較例における高温高湿試験前後の光照射面とは反対側からの撮影写真、図８（ｂ）は実施形態における高温高湿試験前後の光照射面とは反対側からの撮影写真である。FIG. 8A is a photograph taken from the side opposite to the light irradiation surface before and after the high temperature and high humidity test in the comparative example, and FIG. 8B is from the side opposite to the light irradiation surface before and after the high temperature and high humidity test in the embodiment. It is a photograph taken.

以下、添付した図面を参照して本発明の実施形態を詳細に説明する。   Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

図１は、本発明の実施形態に係る光学デバイスの断面図である。図１を参照して、光学デバイス１は、赤外線吸収ガラス２と、この赤外線吸収ガラス２の面上に設けられた反射防止膜３と、を備える。   FIG. 1 is a cross-sectional view of an optical device according to an embodiment of the present invention. Referring to FIG. 1, the optical device 1 includes an infrared absorbing glass 2 and an antireflection film 3 provided on the surface of the infrared absorbing glass 2.

赤外線吸収ガラス２は、可視光透過性基板の一例として、可視光を透過させるとともに、赤外光を吸収できるものであれば特にそのガラス素材に制限されるものではないが、銅イオンを含有するフツリン酸塩系ガラスもしくは銅イオンを含有するリン酸塩系ガラス、等を例示することができる。   The infrared absorbing glass 2 is not particularly limited to the glass material as long as it transmits visible light and can absorb infrared light as an example of a visible light transmissive substrate, but contains copper ions. Examples thereof include fluorophosphate glass or phosphate glass containing copper ions.

反射防止膜３は、赤外線吸収ガラス２の面上に第１層、第２層及び第３層がこの順で３層となって積層された積層膜で構成されている。   The antireflection film 3 is composed of a laminated film in which a first layer, a second layer, and a third layer are laminated in this order on the surface of the infrared absorbing glass 2.

赤外線吸収ガラス２から数えて第１層目は、屈折率が前記３層のうちの中間の層である中屈折率層３ａとなり、赤外線吸収ガラス２から数えて第２層目は屈折率が前記３層のうちの最も高い層である高屈折率層３ｂとなり、赤外線吸収ガラス２から数えて第３層目は屈折率が前記３層のうちの最も低い層である低屈折率層３ｃとなる。   The first layer counted from the infrared absorbing glass 2 becomes a middle refractive index layer 3a which is an intermediate layer of the three layers, and the second layer counted from the infrared absorbing glass 2 has the refractive index described above. The high refractive index layer 3b is the highest layer among the three layers, and the third layer is the low refractive index layer 3c, which is the lowest layer of the three layers, counting from the infrared absorbing glass 2. .

第１層目の中屈折率層３aは、屈折率が１．６〜１．７の範囲でかつ光学膜厚が約1/４λ(ただし、λは光の波長５２０ｎｍ程度、以下同じ。)の屈折率層であり、材料としてはＡｌ２Ｏ３、ＺｒＯ２、Ａｌ２Ｏ３とＺｒＯ２との混合物のうちの少なくともいずれか１種を含む。 The first middle refractive index layer 3a has a refractive index in the range of 1.6 to 1.7 and an optical film thickness of about 1 / 4λ (where λ is a light wavelength of about 520 nm, and so on). the refractive index layers, the material comprises at least any one of a mixture of Al 2 O 3, ZrO 2, Al 2 O 3 and ZrO 2.

第２層目の高屈折率層３ｂは、屈折率が２．０〜２．４の範囲でかつ光学膜厚が約１/２λの屈折率層であり、材料としてはＡｌ２Ｏ３、ＺｒＯ２、Ａｌ２Ｏ３とＺｒＯ２との 混合物のうちの少なくともいずれか１種を含む。 The second high-refractive index layer 3b is a refractive index layer having a refractive index in the range of 2.0 to 2.4 and an optical film thickness of about 1 / 2λ. The material is Al 2 O 3 , ZrO. 2 , at least any one of a mixture of Al 2 O 3 and ZrO 2 is included.

第３層目の低屈折率層３ｃは、屈折率が１．５以下でかつ光学膜厚が約１/４λの屈折率層であり、ＭｇＦ２、その他の材料でもって構成される。 The third low-refractive index layer 3c is a refractive index layer having a refractive index of 1.5 or less and an optical film thickness of about 1 / 4λ, and is composed of MgF 2 and other materials.

このような構成の光学デバイス１においては、図２に例示するように、可視光の波長領域４００〜７００ｎｍでの反射率は１％以下である。ただし、この波長領域の範囲は人間により異なるので一例として示している。すなわち、人の目は、暗所において４００〜６２０ｎｍ程度の範囲の波長の光線に応答し、明所において４２０〜７００ｎｍ程度の範囲の波長の光線に応答する。一方、一般の撮像カメラの撮像素子（ＣＣＤ）では、４００〜７００ｎｍの範囲の波長の光線に高感度で応答し、さらに４００ｎｍ未満の波長の光線や７００ｎｍを越える波長（赤外域）の光線にも応答する。したがって、図２のように可視光の波長領域４００〜７００ｎｍでの反射率を１％以下とすることで、この光学デバイス１を撮像素子の直前の光学系に配置すると、赤外光は、この光学デバイス１で吸収されて撮像素子には到達させずに済む。一方で、可視光は高い透過率で撮像素子に到達できるので、人の目に近い良好な撮像画像が得られるようになる。   In the optical device 1 having such a configuration, as illustrated in FIG. 2, the reflectance of visible light in the wavelength region of 400 to 700 nm is 1% or less. However, since the range of this wavelength region differs depending on the person, it is shown as an example. That is, the human eye responds to light having a wavelength in the range of about 400 to 620 nm in a dark place and responds to light having a wavelength in the range of about 420 to 700 nm in a bright place. On the other hand, an image pickup device (CCD) of a general imaging camera responds with high sensitivity to light having a wavelength in the range of 400 to 700 nm, and also to light having a wavelength of less than 400 nm and light having a wavelength exceeding 700 nm (infrared region). respond. Therefore, when the optical device 1 is arranged in the optical system immediately before the image pickup device by setting the reflectance in the wavelength region 400 to 700 nm of visible light to 1% or less as shown in FIG. It is not necessary to be absorbed by the optical device 1 and reach the image sensor. On the other hand, since visible light can reach the image sensor with high transmittance, a good captured image close to human eyes can be obtained.

実施形態では、反射防止膜３の上面における粒子の平均粒径が２５ｎｍ未満であることに特徴を有する。粒子の平均粒径がこのように極小となると、反射防止膜３の上面の粒子間の隙間の面積が小さくなり、そのため、高温高湿環境下に長時間放置されても、水分が反射防止膜３内部に浸入しにくくなり、白い曇り現象の発生が有効に防止されるものとなっている。   The embodiment is characterized in that the average particle diameter of the particles on the upper surface of the antireflection film 3 is less than 25 nm. When the average particle size of the particles becomes such a minimum, the area of the gap between the particles on the upper surface of the antireflection film 3 becomes small, so that even if the particles are left for a long time in a high-temperature and high-humidity environment, 3 is less likely to enter the interior, and the occurrence of white cloudiness is effectively prevented.

前記反射防止膜３の上面における粒子の平均粒径が２４ｎｍであるとヘイズ値が０．３となるため、平均粒径は２４ｎｍ以下が好ましく、平均粒径が２１ｎｍであるとヘイズ値が０．２未満となるため、平均粒径は２1ｎｍ以下がより好ましい。   Since the haze value is 0.3 when the average particle size of the particles on the upper surface of the antireflection film 3 is 24 nm, the average particle size is preferably 24 nm or less, and when the average particle size is 21 nm, the haze value is 0.00. Since the average particle size is less than 2, the average particle size is more preferably 21 nm or less.

なお、粒径とは、粒子ごとに算術二軸平均径(（長辺＋短辺）／２)で測定した値であり、平均粒径とは、粒子５０個以上について測定した粒径を平均化したものとする。   The particle size is a value measured by arithmetic biaxial average diameter ((long side + short side) / 2) for each particle, and the average particle size is an average of particle sizes measured for 50 or more particles. Suppose that

粒径の測定方法は、前記反射防止膜３の上面におけるＳＥＭ像から得られた特定領域について、粒子５０個以上の長辺および短辺の長さを計測して行った。   The particle size was measured by measuring the length of the long side and the short side of 50 or more particles in a specific region obtained from the SEM image on the upper surface of the antireflection film 3.

また、反射防止膜３の上面とは、反射防止膜３において、大気と接する面のことである。   The upper surface of the antireflection film 3 is a surface in the antireflection film 3 that is in contact with the atmosphere.

このことを、図３を参照して、従来と実施の形態それぞれの反射防止膜上面の状態を説明すると、図３（ａ）は従来の反射防止膜の上面の状態を示し、図３（ｂ）は実施形態の反射防止膜の上面の状態を示す。従来の場合、反射防止膜の上面での各粒子４ａは直径が各種であるが、粒子４ａの平均粒径が２５ｎｍ以上であるために、図３（ａ）に模式的に示すように各粒子４ａ間の隙間５ａの面積が大きくなり、そのため、高温高湿下で長時間にわたり放置されると、水分が反射防止膜の上面を形成する各粒子４ａ間の隙間５ａから反射防止膜３内部に容易に浸入して、白い曇り現象が発生するようになる。   With reference to FIG. 3, the state of the upper surface of the conventional antireflection film will be described with reference to FIG. 3. FIG. 3 (a) shows the state of the upper surface of the conventional antireflection film, and FIG. ) Shows the state of the upper surface of the antireflection film of the embodiment. In the conventional case, each particle 4a on the upper surface of the antireflection film has various diameters. However, since the average particle diameter of the particle 4a is 25 nm or more, each particle as shown schematically in FIG. The area of the gap 5a between 4a becomes large. Therefore, when left for a long time under high temperature and high humidity, moisture enters the antireflection film 3 from the gap 5a between the particles 4a forming the upper surface of the antireflection film. It easily penetrates and a white clouding phenomenon occurs.

これに対して、実施形態では、反射防止膜３の上面を形成する各粒子４ｂは直径が各種であるが、粒子４ｂの平均粒径が２５ｎｍ未満であるために、図３（ｂ）に模式的に示すように反射防止膜３の上面における各粒子４ｂ間の隙間の面積が小さくなり、高温高湿下で長時間にわたり放置されても、水分は反射防止膜３の上面から反射防止膜３内部に容易には浸入しなくなる。したがって、反射防止膜３を構成する各屈折率層３ａ〜３ｃの境界あるいは、反射防止膜３と赤外線吸収ガラス２との境界にも水分が浸入しにくくなり、白い曇り現象の発生が長期にわたり有効に防止される。   On the other hand, in the embodiment, each particle 4b forming the upper surface of the antireflection film 3 has various diameters, but the average particle diameter of the particles 4b is less than 25 nm. As shown in the figure, the area of the gap between each particle 4b on the upper surface of the antireflection film 3 is reduced, and even if the space is left for a long time under high temperature and high humidity, the moisture is reflected from the upper surface of the antireflection film 3 to the antireflection film 3. It will not easily enter the interior. Therefore, it becomes difficult for moisture to enter the boundary between the refractive index layers 3a to 3c constituting the antireflection film 3 or the boundary between the antireflection film 3 and the infrared absorbing glass 2, and the occurrence of white clouding phenomenon is effective for a long time. To be prevented.

図４は他の実施形態の光学デバイスの断面図である。この実施形態では、反射防止膜３が赤外線吸収ガラス２から数えて第１層目の高屈折率層３ｄと、赤外線吸収ガラス２から数えて第２層目の低屈折率層３ｅとの合計２層からなる。   FIG. 4 is a cross-sectional view of an optical device according to another embodiment. In this embodiment, the antireflection film 3 is a total of 2 of the first high refractive index layer 3 d counted from the infrared absorbing glass 2 and the second low refractive index layer 3 e counted from the infrared absorbing glass 2. Consists of layers.

第１層目の高屈折率層３ｄは、屈折率が２．０〜２．４の範囲でかつ光学膜厚が約1/２λの屈折率層であり、材料としてはＡｌ２Ｏ３、ＺｒＯ２、Ａｌ２Ｏ３とＺｒＯ２との混合物のうちの少なくともいずれか１種を含む。 The first high-refractive index layer 3d is a refractive index layer having a refractive index in the range of 2.0 to 2.4 and an optical film thickness of about 1 / 2λ, and is made of Al 2 O 3 , ZrO. 2 , at least any one of a mixture of Al 2 O 3 and ZrO 2 is included.

第２層目の低屈折率層３ｅは、屈折率が１．５以下でかつ光学膜厚が約１/４λの屈折率層であり、ＭｇＦ２、その他の材料でもって構成される。 The second low-refractive index layer 3e is a refractive index layer having a refractive index of 1.5 or less and an optical film thickness of about 1 / 4λ, and is composed of MgF 2 and other materials.

この実施形態の場合も、反射防止膜３の表面の粒子の平均粒径が、２５ｎｍ未満であり、反射防止膜の膜表面における各粒子間の面積が小さくなり、高温高湿環境下でも水分が反射防止膜３内部に浸入しにくくなり、白い曇り現象の発生が防止されるものとなっている。   Also in this embodiment, the average particle diameter of the particles on the surface of the antireflection film 3 is less than 25 nm, the area between the particles on the film surface of the antireflection film is reduced, and moisture remains even in a high temperature and high humidity environment. It becomes difficult to enter the antireflection film 3 and the occurrence of white fogging phenomenon is prevented.

図５は、さらに他の実施形態の光学デバイスの断面図である。この実施形態では、反射防止膜３が、赤外線吸収ガラス２から数えて第１層目の中屈折率層３ｆと、赤外線吸収ガラス２から数えて第２層目の低屈折率層３ｇとの合計２層からなる。   FIG. 5 is a cross-sectional view of an optical device according to still another embodiment. In this embodiment, the antireflection film 3 is a total of the first middle refractive index layer 3 f counted from the infrared absorbing glass 2 and the second lower refractive index layer 3 g counted from the infrared absorbing glass 2. It consists of two layers.

第１層目の中屈折率層３ｆは、屈折率が１．６〜１．７の範囲でかつ光学膜厚が１/４λ〜１/２λの範囲の屈折率層であり、Ａｌ２Ｏ３、ＺｒＯ２、Ａｌ２Ｏ３とＺｒＯ２との混合物のうちの少なくともいずれか１種を含む。 The first medium refractive index layer 3f is a refractive index layer having a refractive index in the range of 1.6 to 1.7 and an optical film thickness in the range of 1 / 4λ to 1 / 2λ. Al 2 O 3 , ZrO 2 , Al 2 O 3 , and a mixture of ZrO 2 .

第２層目の低屈折率層３ｇは、屈折率が１．５以下でかつ光学膜厚が約１/４λの屈折率層であり、ＭｇＦ２、その他の材料でもって構成される。 The second low-refractive index layer 3g is a refractive index layer having a refractive index of 1.5 or less and an optical film thickness of about 1 / 4λ, and is composed of MgF 2 and other materials.

この実施形態の場合も、反射防止膜３の表面の粒子の平均粒径が、２５ｎｍ未満であり、反射防止膜３の上面における各粒子間の隙間の面積が小さくなり、高温高湿環境下でも水分が反射防止膜３内部に浸入しにくくなり、白い曇り現象の発生が防止されるものとなっている。   Also in this embodiment, the average particle size of the particles on the surface of the antireflection film 3 is less than 25 nm, the area of the gap between the particles on the upper surface of the antireflection film 3 is reduced, and even in a high temperature and high humidity environment. Moisture does not easily enter the antireflection film 3, and the occurrence of white clouding is prevented.

図６は、さらに他の実施形態の光学デバイス1ｃの断面図である。この実施形態では、反射防止膜３が、赤外線吸収ガラス２から数えて奇数層目を高屈折率層、偶数層目を低屈折率層とし交互に積層してｎ（ｎ＝１，２，３，４，…）層からなる反射防止膜の一例として、赤外線吸収ガラス２から数えて、第１層目の高屈折率層３ｈと、第２層目の低屈折率層３iと、第３層目の高屈折率層３ｊと、第４層目の低屈折率層３ｋと、の合計４層からなる。   FIG. 6 is a cross-sectional view of an optical device 1c according to still another embodiment. In this embodiment, the antireflective film 3 is alternately stacked by counting the odd-numbered layers from the infrared-absorbing glass 2 as the high-refractive index layers and the even-numbered layers as the low-refractive index layers, and n (n = 1, 2, 3). , 4,...) As an example of an antireflection film composed of layers, the first high-refractive index layer 3h, the second low-refractive index layer 3i, and the third layer counted from the infrared absorbing glass 2 It consists of a total of four layers, a high refractive index layer 3j of the eye and a low refractive index layer 3k of the fourth layer.

第１層目の高屈折率層３ｈは、屈折率が２．０〜２．４の範囲でかつ光学膜厚が約０．１３λの屈折率層であり、材料としてはＡｌ２Ｏ３、ＺｒＯ２、Ａｌ２Ｏ３とＺｒＯ２との混合物のうちの少なくともいずれか１種を含む。 The first high-refractive index layer 3h is a refractive index layer having a refractive index in the range of 2.0 to 2.4 and an optical film thickness of about 0.13λ, and is made of Al 2 O 3 , ZrO. 2 , at least any one of a mixture of Al 2 O 3 and ZrO 2 is included.

第２層目の低屈折率層３iは、屈折率が１．５以下でかつ光学膜厚が約０．０８λの屈折率層であり、ＭｇＦ２、ＳｉＯ２、その他の材料でもって構成される。 The second low-refractive index layer 3i is a refractive index layer having a refractive index of 1.5 or less and an optical film thickness of about 0.08λ, and is composed of MgF 2 , SiO 2 , and other materials. .

第３層目の高屈折率層３ｊは、屈折率が２．０〜２．４の範囲でかつ光学膜厚が約０．１６λの屈折率層であり、材料としてはＺｒＯ２、ＴｉＯ２、その他の材料でもって構成される。 The third high-refractive index layer 3j is a refractive index layer having a refractive index in the range of 2.0 to 2.4 and an optical film thickness of about 0.16λ. The materials include ZrO 2 , TiO 2 , Consists of other materials.

第４層目の低屈折率層３ｋは、屈折率が１．５以下でかつ光学膜厚が約０．２５λの屈折率層であり、ＭｇＦ２、ＳｉＯ２、その他の材料でもって構成される。 The fourth low refractive index layer 3k is a refractive index layer having a refractive index of 1.5 or less and an optical film thickness of about 0.25λ, and is composed of MgF 2 , SiO 2 , and other materials. .

この実施形態の場合も、反射防止膜３の表面の粒子の平均粒径が、２５ｎｍ未満であり、反射防止膜３の上面における各粒子間の隙間の面積が小さくなり、高温高湿環境下でも水分が反射防止膜３内部に浸入しにくくなり、白い曇り現象の発生が防止されるものとなっている。   Also in this embodiment, the average particle size of the particles on the surface of the antireflection film 3 is less than 25 nm, the area of the gap between the particles on the upper surface of the antireflection film 3 is reduced, and even in a high temperature and high humidity environment. Moisture does not easily enter the antireflection film 3, and the occurrence of white clouding is prevented.

（実施例）
＜光学デバイスの製造方法＞
実施例の光学デバイスは、赤外線吸収ガラスと反射防止膜とからなり、反射防止膜は図１と同様に３層の積層膜（屈折率層）から構成される。赤外線吸収ガラスは、平面視サイズが縦横２０ｍｍ×３０ｍｍ程度、厚み０．３０ｍｍ程度、屈折率１．５６で銅イオンを含むフツリン酸ガラスを用いた。 (Example)
<Optical device manufacturing method>
The optical device of the example is composed of an infrared absorbing glass and an antireflection film, and the antireflection film is composed of a laminated film (refractive index layer) of three layers as in FIG. As the infrared absorbing glass, a fluorophosphate glass having a size in plan view of about 20 mm × 30 mm, a thickness of about 0.30 mm and a refractive index of 1.56 and containing copper ions was used.

反射防止膜を構成する第１層から第３層までの平面視サイズは赤外線吸収ガラスと同じであり、第１層目の中屈折率層は、屈折率１．７０で光学膜厚１/４λであるＡｌ２Ｏ３とＺｒＯ２との混合物からなる。第２層目の高屈折率層は、屈折率２．１０で光学膜厚１/２λのＺｒＯ２で構成される。第３層目の低屈折率層は、屈折率１．３８で光学膜厚１/４λのＭｇＦ２で構成される。 The size in plan view from the first layer to the third layer constituting the antireflection film is the same as that of the infrared absorbing glass, and the first middle refractive index layer has a refractive index of 1.70 and an optical film thickness of 1 / 4λ. It consists of a mixture of Al 2 O 3 and ZrO 2 . The second high refractive index layer is made of ZrO 2 having a refractive index of 2.10 and an optical film thickness of 1 / 2λ. The third low refractive index layer is made of MgF 2 having a refractive index of 1.38 and an optical film thickness of 1 / 4λ.

各層の形成方法を説明すると、洗浄された赤外線吸収ガラスを真空蒸着装置にセットし、真空排気を行った後に、各層の成膜のための真空蒸着を開始した。真空蒸着時の赤外線吸収ガラスの温度を任意に変更を行った。各層の光学膜厚は、光学式膜厚監視法に基づいてモニターガラス上の反射率を制御することにより行った。なお、ヘイズ値（濁り度）は、高温高湿試験前後にＪＩＳ７１３６に沿って測定した。   Explaining the method of forming each layer, the cleaned infrared absorbing glass was set in a vacuum deposition apparatus, and after vacuum evacuation, vacuum deposition for film formation of each layer was started. The temperature of the infrared absorbing glass during vacuum deposition was arbitrarily changed. The optical film thickness of each layer was performed by controlling the reflectance on the monitor glass based on the optical film thickness monitoring method. The haze value (turbidity) was measured according to JIS 7136 before and after the high temperature and high humidity test.

表１に示す温度は、反射防止膜の各層を成膜する際の前記真空蒸着時の赤外線吸収ガラスの温度のことであり、表１において「低←温度→高」のうち、「低←」は矢印方向に温度が低くなり、「→高」は矢印方向に温度が高くなることを示す。同じく、表１に示すヘイズ値は、ＪＩＳ７１３６に沿って測定された値であり、高温高湿試験後における光学デバイスの白い曇り現象を数値化したものである。一般的にヘイズ値０．３以下の曇りの程度はカメラの撮影画像において許容できる範囲とされ、ヘイズ値０．２以下の曇りの程度は、カメラの撮影画像において影響がない範囲とされる。また、表１では、反射防止膜の上面における粒径およびヘイズ値より、（１）−（３）は、適正温度を示し、（４）、（５）は許容温度を示し、（６）、（７）は過剰温度、例えば３００℃以上を示す。   The temperature shown in Table 1 is the temperature of the infrared absorbing glass at the time of vacuum deposition when forming each layer of the antireflection film. In Table 1, “Low ←” among “Low ← Temperature → High”. Indicates that the temperature decreases in the direction of the arrow, and “→ high” indicates that the temperature increases in the direction of the arrow. Similarly, the haze value shown in Table 1 is a value measured according to JIS7136, and is a numerical value of the white clouding phenomenon of the optical device after the high temperature and high humidity test. In general, the degree of cloudiness with a haze value of 0.3 or less is an allowable range in a photographed image of the camera, and the degree of cloudiness with a haze value of 0.2 or less is a range that has no influence on the photographed image of the camera. In Table 1, from the particle size and haze value on the upper surface of the antireflection film, (1) to (3) indicate appropriate temperatures, (4) and (5) indicate allowable temperatures, (6), (7) indicates an excess temperature, for example, 300 ° C. or higher.

いずれの適正温度（１）、（２）、（３）においても、反射防止膜の上面における粒子の平均粒径はそれぞれ１６ｎｍ、１７ｎｍ、２１ｎｍとなり、各粒子間の隙間の面積が小さくなる。またそれぞれのヘイズ値は、０．１１、０．０９、０．１６であり、白い曇り現象の発生は見られない。   At any appropriate temperature (1), (2), (3), the average particle diameter of the particles on the upper surface of the antireflection film is 16 nm, 17 nm, and 21 nm, respectively, and the area of the gap between the particles is reduced. Moreover, each haze value is 0.11, 0.09, and 0.16, and generation | occurrence | production of a white cloudiness phenomenon is not seen.

また、許容温度（４）、（５）では、反射防止膜の上面における粒子の平均粒径はそれぞれ２２ｎｍ、２４ｎｍであり、各粒子間の隙間の面積が前記適正温度（１）、（２）、（３）の場合よりも大きくなる。またそれぞれのヘイズ値は、０．２０、０．３０であり、白い曇り現象はわずかに確認できるものの許容できるものである。   In the allowable temperatures (4) and (5), the average particle diameter of the particles on the upper surface of the antireflection film is 22 nm and 24 nm, respectively, and the area of the gap between the particles is the appropriate temperature (1) and (2). , (3) larger than the case. Moreover, each haze value is 0.20 and 0.30, and although a white cloudiness phenomenon can be confirmed slightly, it is permissible.

また、過剰温度（６）、（７）では、反射防止膜の上面における粒子の平均粒径はそれぞれ２５ｎｍ、３０ｎｍであり、各粒子間の隙間の面積が大きくなる。またそれぞれのヘイズ値は０．３７、０．６６であり、白い曇り現象がはっきりと確認することができる。   At excessive temperatures (6) and (7), the average particle size of the particles on the top surface of the antireflection film is 25 nm and 30 nm, respectively, and the area of the gap between the particles is large. Moreover, each haze value is 0.37 and 0.66, and the white cloudiness phenomenon can be confirmed clearly.

すなわち、粒子の平均粒径が２５ｎｍ未満において、各粒子間の隙間の面積が小さくなるため高温高湿試験後におけるヘイズ値が小さい。つまり、光学デバイスの白い曇り現象の発生はほとんどなかった。   That is, when the average particle size of the particles is less than 25 nm, the area of the gap between the particles is small, so the haze value after the high temperature and high humidity test is small. That is, there was almost no occurrence of the white clouding phenomenon of the optical device.

製造した光学デバイスの反射防止膜の上面の粒子の平均粒径が１７ｎｍと３０ｎｍそれぞれのＳＥＭ像を図７に示す。図７（ａ）は、適正温度で赤外線吸収ガラス上に反射防止膜を成膜した場合の光学デバイスにおける表面状態を示す。図７（ｂ）は、過剰温度で赤外線吸収ガラス上に反射防止膜を成膜した場合の光学デバイスにおける表面状態を示す。   FIG. 7 shows SEM images in which the average particle size of the particles on the upper surface of the antireflection film of the manufactured optical device is 17 nm and 30 nm, respectively. Fig.7 (a) shows the surface state in an optical device at the time of forming an anti-reflective film on infrared rays absorption glass at appropriate temperature. FIG. 7B shows a surface state in the optical device when an antireflection film is formed on the infrared absorbing glass at an excessive temperature.

これらのＳＥＭ像を比較して明らかであるように、図７（ａ）のように適正温度で反射防止膜を成膜した場合は、反射防止膜の上面における粒子の平均粒径は１７ｎｍと小さくなり、反射防止膜の上面における各粒子間の隙間の面積が小さくなることが分かる。一方、図７（ｂ）のように過剰温度で反射防止膜を成膜した場合は、反射防止膜の上面における粒子の平均粒径は３０ｎｍと大きくなって、反射防止膜の上面における各粒子間の隙間の面積が大きくなることが分かる。   As is clear by comparing these SEM images, when the antireflection film is formed at an appropriate temperature as shown in FIG. 7A, the average particle diameter of the particles on the upper surface of the antireflection film is as small as 17 nm. Thus, it can be seen that the area of the gap between the particles on the upper surface of the antireflection film is reduced. On the other hand, when the antireflection film is formed at an excessive temperature as shown in FIG. 7B, the average particle diameter of the particles on the upper surface of the antireflection film is as large as 30 nm, It can be seen that the area of the gap increases.

図８（ａ）（ｂ）は、比較例と実施例との高温高湿試験前後の白い曇り現象の発生の状態を示す写真である。図８（ａ）は、過剰温度で作製し粒子の平均粒径が３０ｎｍの比較例の光学デバイスであり、図８（ｂ）は、適正温度で作製し粒子の平均粒径が１７ｎｍの実施例の光学デバイスである。それぞれの図８（ａ）（ｂ）で左側が高温高湿試験後、右側が高温高湿試験前である。光学デバイスには、背面から光を透過させた。   FIGS. 8A and 8B are photographs showing the state of occurrence of white clouding before and after the high-temperature and high-humidity test in the comparative example and the example. FIG. 8A shows an optical device of a comparative example manufactured at an excessive temperature and having an average particle diameter of 30 nm, and FIG. 8B shows an embodiment having an average particle diameter of 17 nm manufactured at an appropriate temperature. It is an optical device. 8A and 8B, the left side is after the high temperature and high humidity test, and the right side is before the high temperature and high humidity test. Light was transmitted through the optical device from the back.

図８（ａ）で示す比較例について説明すると、高温高湿試験前では図８（ａ）の右側の写真に示すように光がほぼ透過して光学デバイス表面で散乱していないので暗く写っている。しかし、高温高湿試験後では図８（ａ）の左側の写真に示すように光学デバイス内部に水分が浸透し、基板の一部が溶解した結果、空間ができることにより光が散乱されて全体が白く曇っていることが分かる。   The comparative example shown in FIG. 8A will be described. Before the high-temperature and high-humidity test, as shown in the photograph on the right side of FIG. 8A, light is almost transmitted and is not scattered on the optical device surface, so it appears dark. Yes. However, after the high-temperature and high-humidity test, as shown in the photograph on the left side of FIG. 8 (a), moisture penetrates into the optical device and a part of the substrate dissolves, resulting in a space that is scattered and the whole is scattered. You can see that it is cloudy white.

これに対して、図８（ｂ）で示す実施例について説明すると、高温高湿試験前では図８（ｂ）の右側の写真に示すように光がほぼ透過して光学デバイス表面で反射していないので暗く写っている。また、高温高湿試験後でも図８（ｂ）の左側の写真に示すように光学デバイス内部には水分が浸透していないので、白く曇らず、透明であることが分かる。つまり、高温高湿試験前後で光学デバイスにおける光の透過性に変化がないことが明らかである。   On the other hand, the embodiment shown in FIG. 8B will be described. Before the high-temperature and high-humidity test, as shown in the photograph on the right side of FIG. It is dark because it is not. Further, even after the high temperature and high humidity test, as shown in the left photograph of FIG. 8B, moisture does not permeate the inside of the optical device. That is, it is clear that there is no change in light transmittance in the optical device before and after the high temperature and high humidity test.

以上のように、実施例の光学デバイスは、反射防止膜の上面における粒子の平均粒径は２５ｎｍ未満であるので、高温高湿の環境下でも、白く曇る現象は起きず、光学デバイスとしての性能を長期にわたり維持することができる耐候性に優れたものである。   As described above, in the optical device of the example, since the average particle size of the particles on the upper surface of the antireflection film is less than 25 nm, the phenomenon of white cloudiness does not occur even in a high-temperature and high-humidity environment, and the performance as an optical device. Can be maintained over a long period of time.

なお、上記した実施形態では、低屈折率層、中屈折率層、及び高屈折率層を用いた３層による反射防止膜と、高屈折率層及び低屈折率層を用いた２層による反射防止膜と、中屈折率層及び低屈折率層を用いた２層による反射防止膜と、高屈折率層及び低屈折率層を用いたｎ層の反射防止膜（実施形態ではｎ＝４）を例に挙げているが、反射防止膜の設計はこれら実施形態に限定されるものではなく、所望の反射防止特性が得られる、各屈折率層と層数の組み合わせで構成しても良い。   In the above-described embodiment, the antireflection film by three layers using the low refractive index layer, the middle refractive index layer, and the high refractive index layer, and the reflection by the two layers using the high refractive index layer and the low refractive index layer. Antireflection film, two-layer antireflection film using medium refractive index layer and low refractive index layer, and n antireflection film using high refractive index layer and low refractive index layer (n = 4 in the embodiment) However, the design of the antireflection film is not limited to these embodiments, and the antireflection film may be configured by a combination of each refractive index layer and the number of layers, which can obtain a desired antireflection characteristic.

本発明は、その精神又は主要な特徴から逸脱することなく、他のいろいろな形で実施することができる。そのため、上述の実施形態及び実施例はあらゆる点で単なる例示にすぎず、限定的に解釈してはならない。本発明の範囲は特許請求の範囲によって示すものであって、明細書本文には、なんら拘束されない。さらに、特許請求の範囲の均等範囲に属する変形や変更は、全て本発明の範囲内のものである。   The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiments and examples are merely examples in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

１，１ａ，１ｂ，１ｃ 光学デバイス
２ 赤外線吸収ガラス
３ 反射防止膜
３ａ 第１層目の中屈折率層
３ｂ 第２層目の高屈折率層
３ｃ 第３層目の低屈折率層
３ｄ 第１層目の高屈折率層
３ｅ 第２層目の低屈折率層
３ｆ 第１層目の中屈折率層
３ｇ 第２層目の低屈折率層
３ｈ 第１層目の高屈折率層
３ｉ 第２層目の低屈折率層
３ｊ 第３層目の高屈折率層
３ｋ 第４層目の低屈折率層 1, 1a, 1b, 1c Optical device 2 Infrared absorbing glass 3 Antireflection film 3a First refractive index layer 3b Second high refractive index layer 3c Third low refractive index layer 3d First High refractive index layer 3e Second low refractive index layer 3f First middle refractive index layer 3g Second low refractive index layer 3h First high refractive index layer 3i Second Low refractive index layer 3j Third high refractive index layer 3k Fourth low refractive index layer

本発明は、赤外線吸収ガラス等の可視光透過性基板の面上に反射防止膜（ＡＲ膜:Anti Reflection）が形成されてある光学デバイスに関するものである。なお、本明細書で言う屈折率は、大気中での屈折率である。 The present invention relates to an optical device in which an antireflection film (AR film : Anti Reflection ) is formed on the surface of a visible light transmissive substrate such as infrared absorbing glass. In addition, the refractive index said in this specification is a refractive index in air | atmosphere.

デジタルカメラ等で使用されるＣＣＤ、ＣＭＯＳなどの撮像素子の分光感度は、可視光の領域から赤外光の領域にわたる。撮像素子の直前の光学系において、前記可視光透過性基板として、例えば赤外線吸収ガラスを用いたものでは、撮像素子に入射する光のうち、赤外光を赤外線吸収ガラスにより吸収し、可視光を撮像素子に受光できるようにして、撮像画像を人間の視感度に近似させている。そして、この赤外線吸収ガラスなどの可視光透過性基板の表面に反射防止膜を成膜することで、可視光の反射損失を低減し、透過率を向上させるようにしている。 The spectral sensitivity of an image sensor such as a CCD or CMOS used in a digital camera or the like ranges from the visible light region to the infrared light region. In the optical system immediately before the image pickup device , for example, an infrared absorbing glass is used as the visible light transmissive substrate. Of the light incident on the image pickup device, infrared light is absorbed by the infrared absorbing glass, and visible light is absorbed. The captured image is approximated to human visibility so that the image sensor can receive light. Then, an antireflection film is formed on the surface of a visible light transmissive substrate such as an infrared ray absorbing glass, thereby reducing the reflection loss of visible light and improving the transmittance.

（１）上記の目的を達成するために、本発明に係る光学デバイスは、可視光透過性基板の少なくとも１つの面上に可視光の反射を防止する反射防止膜を備えた光学デバイスであって、前記反射防止膜が、屈折率が異なる少なくとも２層以上の屈折率層が積層されて構成されていると共に、前記少なくとも２層以上の屈折率層のうち、屈折率が低い屈折率層以外の、少なくとも1層以上の屈折率層に、その材料としてＡｌ2Ｏ3又はＺｒＯ2又はこれらの混合物を少なくとも含み、かつ、前記反射防止膜の上面における粒子の平均粒径が２５ｎｍ未満である、ことを特徴とするものである。 (1) In order to achieve the above object, an optical device according to the present invention is an optical device including an antireflection film for preventing reflection of visible light on at least one surface of a visible light transmissive substrate. The antireflection film is formed by laminating at least two or more refractive index layers having different refractive indexes, and of the at least two or more refractive index layers other than the refractive index layer having a low refractive index. The at least one refractive index layer contains at least Al 2 O 3 or ZrO 2 as a material thereof, or a mixture thereof, and the average particle size of the particles on the upper surface of the antireflection film is less than 25 nm. It is characterized by.

（２）本発明の前記（１）において好ましい実施態様は、前記屈折率が異なる少なくとも２層以上の屈折率層が、前記可視光透過性基板の面上に積層されて構成されているとともに、少なくとも可視光透過性基板から数えて第１層目の屈折率層に、その材料としてＡｌ2Ｏ3又はＺｒＯ2又はこれらの混合物を少なくとも含む。 (2) In a preferred embodiment of (1) of the present invention, at least two or more refractive index layers having different refractive indexes are laminated on the surface of the visible light transmissive substrate, At least Al 2 O 3 or ZrO 2 or a mixture thereof is included in the first refractive index layer counted from the visible light transmissive substrate.

この場合、少なくとも可視光透過性基板から数えて第１層目の屈折率層の材料が、Ａｌ2Ｏ3又はＺｒＯ2又はこれらの混合物を少なくとも含むもので構成することで、中屈折率層として、屈折率が１．６〜１．７の範囲にあるＡｌ2Ｏ3、もしくは高屈折率層として、屈折率が２．０〜２．４の範囲にあるＺｒＯ2が形成されるので、多数層からなる反射防止膜の設計が容易に行えるといったメリットがある。結果として、可視光領域全体に反射防止効果をもつ分光特性を得ることができる。しかしながら、少なくとも可視光透過性基板から数えて第１層目の屈折率層の材料が、Ａｌ2Ｏ3又はＺｒＯ2又はこれらの混合物を少なくとも含むものであると、水分が浸入した際に基板を溶解させやすく作用することがあり、従来の問題点がより顕著に生じやすい。これに対して上述の構成と組み合わせることで、反射防止膜中に水分が容易に浸入することを防止できるようになり、白く曇ることが防止され、可視光の透過性を維持できる。 In this case, the material of the first refractive index layer at least counted from the visible light transmissive substrate is composed of at least Al 2 O 3, ZrO 2, or a mixture thereof. Since Al 2 O 3 having a refractive index in the range of 1.6 to 1.7, or ZrO 2 having a refractive index in the range of 2.0 to 2.4 is formed as the high refractive index layer, a large number of There is an advantage that an antireflection film composed of layers can be easily designed. As a result, it is possible to obtain spectral characteristics having an antireflection effect over the entire visible light region. However, if the material of at least the first refractive index layer counted from the visible light transmissive substrate contains at least Al 2 O 3, ZrO 2, or a mixture thereof, the substrate is dissolved when moisture enters. The conventional problems may be more prominent. On the other hand, by combining with the above-described configuration, it becomes possible to prevent moisture from easily entering the antireflection film, to prevent white fogging, and to maintain visible light permeability.

図１は本発明の実施形態に係る光学デバイスの断面図である。FIG. 1 is a cross-sectional view of an optical device according to an embodiment of the present invention. 図２は前記光学デバイスの波長対反射率特性図である。FIG. 2 is a wavelength vs. reflectance characteristic diagram of the optical device. 図３（ａ）は比較例の表面における粒子状態の模式図、図３（ｂ）は実施形態の表面における粒子状態の模式図である。FIG. 3A is a schematic diagram of the particle state on the surface of the comparative example, and FIG. 3B is a schematic diagram of the particle state on the surface of the embodiment. 図４は本発明の他の実施形態に係る光学デバイスの断面図である。FIG. 4 is a cross-sectional view of an optical device according to another embodiment of the present invention. 図５は本発明のさらに他の実施形態に係る光学デバイスの断面図である。FIG. 5 is a cross-sectional view of an optical device according to still another embodiment of the present invention. 図６は本発明のさらに他の実施形態に係る光学デバイスの断面図である。FIG. 6 is a cross-sectional view of an optical device according to still another embodiment of the present invention. 図７（ａ）は適正温度で作製した光学デバイスにおける反射防止膜の上面における粒子状態を示すＳＥＭ像(走査型電子顕微鏡写真像)、図７（ｂ）は過剰温度で作製した光学デバイスにおける反射防止膜の上面における粒子状態を示すＳＥＭ像である。7A is an SEM image (scanning electron micrograph image) showing the particle state on the upper surface of the antireflection film in an optical device manufactured at an appropriate temperature, and FIG. 7B is a reflection in an optical device manufactured at an excessive temperature. It is a SEM image which shows the particle state in the upper surface of a prevention film. 図８（ａ）は比較例における高温高湿試験前後の光照射面とは反対側からの撮影写真、図８（ｂ）は実施形態における高温高湿試験前後の光照射面とは反対側からの撮影写真である。FIG. 8A is a photograph taken from the side opposite to the light irradiation surface before and after the high temperature and high humidity test in the comparative example, and FIG. 8B is from the side opposite to the light irradiation surface before and after the high temperature and high humidity test in the embodiment. It is a photograph taken.

反射防止膜３において、赤外線吸収ガラス２から数えて第１層目は、屈折率が前記３層のうちの中間の層である中屈折率層３ａとなり、赤外線吸収ガラス２から数えて第２層目は屈折率が前記３層のうちの最も高い層である高屈折率層３ｂとなり、赤外線吸収ガラス２から数えて第３層目は屈折率が前記３層のうちの最も低い層である低屈折率層３ｃとなる。 In the antireflection film 3, the first layer counted from the infrared absorbing glass 2 becomes a middle refractive index layer 3 a that is an intermediate layer of the three layers, and the second layer counted from the infrared absorbing glass 2. The eye becomes a high refractive index layer 3b having the highest refractive index among the three layers, and the third layer counted from the infrared absorbing glass 2 is a low refractive index layer having the lowest refractive index among the three layers. It becomes the refractive index layer 3c.

上記目的を達成するため、本発明に係る光学デバイスは、可視光透過性基板の少なくとも１つの面上に可視光の反射を防止する反射防止膜を備えた光学デバイスであって、
前記反射防止膜が、屈折率が異なる少なくとも２層以上の屈折率層が積層されて構成されていると共に、前記少なくとも２層以上の屈折率層のうち、屈折率が低い屈折率層以外の、少なくとも1層以上に、その材料としてＡｌ2Ｏ3又はＺｒＯ2又はこれらの混合物を少なくとも含み、かつ、前記反射防止膜の上面は前記屈折率が低い屈折率層の上面で構成されていると共に、当該上面における粒子の平均粒径が２５ｎｍ未満である、ことを特徴とするものである。 To achieve the above object, an optical device according to the present invention is an optical device comprising an antireflection film for preventing reflection of visible light on at least one surface of a visible light transmissive substrate,
The antireflection film is configured by laminating at least two refractive index layers having different refractive indexes, and of the at least two refractive index layers other than the refractive index layer having a low refractive index, At least one layer includes at least Al 2 O 3 or ZrO 2 or a mixture thereof, and the top surface of the antireflection film is composed of the top surface of the refractive index layer having a low refractive index, The average particle size of the particles on the upper surface is less than 25 nm.

Claims (3)

可視光透過性基板の少なくとも１つの面上に可視光の反射を防止する反射防止膜を備えた光学デバイスであって、
前記反射防止膜が、屈折率が異なる少なくとも２層以上の屈折率層が積層されて構成されていると共に、前記少なくとも２層以上の屈折率層のうち、屈折率が低い屈折率層以外の、少なくとも1層以上に、その材料としてＡｌ２Ｏ３又はＺｒＯ２又はこれらの混合物を少なくとも含み、かつ、前記反射防止膜の上面における粒子の平均粒径が２５ｎｍ未満である、ことを特徴とする光学デバイス。 An optical device comprising an antireflection film for preventing reflection of visible light on at least one surface of a visible light transmissive substrate,
The antireflection film is configured by laminating at least two refractive index layers having different refractive indexes, and of the at least two refractive index layers other than the refractive index layer having a low refractive index, An optical system comprising at least one layer including at least Al 2 O 3 or ZrO 2 or a mixture thereof, and having an average particle size of particles on the upper surface of the antireflection film of less than 25 nm. device. 前記屈折率が異なる少なくとも２層以上の屈折率層が、前記可視光透過性基板の面上に積層されて構成されているとともに、少なくとも可視光透過性基板から数えて第１層目に、その材料としてＡｌ２Ｏ３又はＺｒＯ２又はこれらの混合物を少なくとも含む、ことを特徴とする請求項１に記載の光学デバイス。 The refractive index layers of at least two layers having different refractive indexes are laminated on the surface of the visible light transmissive substrate, and at least the first layer counted from the visible light transmissive substrate, The optical device according to claim 1, comprising at least Al 2 O 3 or ZrO 2 or a mixture thereof as a material. 前記可視光透過性基板の材料が、銅イオンを含有するフツリン酸塩系ガラスもしくは、リン酸塩系ガラスである、ことを特徴とする請求項１又は２に記載の光学デバイス。   The optical device according to claim 1 or 2, wherein the material of the visible light transmissive substrate is a fluorophosphate glass or a phosphate glass containing copper ions.
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