JP2000329933A - Multilayered film filter - Google Patents

Multilayered film filter

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Publication number
JP2000329933A
JP2000329933A JP11136429A JP13642999A JP2000329933A JP 2000329933 A JP2000329933 A JP 2000329933A JP 11136429 A JP11136429 A JP 11136429A JP 13642999 A JP13642999 A JP 13642999A JP 2000329933 A JP2000329933 A JP 2000329933A
Authority
JP
Japan
Prior art keywords
refractive index
film thickness
index layer
optical film
low refractive
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
JP11136429A
Other languages
Japanese (ja)
Inventor
Hiroshi Ikeda
浩 池田
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Olympus Corp
Original Assignee
Olympus Optical Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Olympus Optical Co Ltd filed Critical Olympus Optical Co Ltd
Priority to JP11136429A priority Critical patent/JP2000329933A/en
Publication of JP2000329933A publication Critical patent/JP2000329933A/en
Withdrawn legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To produce a multilayered film filter that the width of the inhibition range can be changed without changing the film material. SOLUTION: The multilayered film filter is produced by laminating two or more kinds of substances having different refractive indices. In this method, a high refractive index material H and a low refractive index material L are laminated for the design wavelength λ in such a manner that the film includes a portion where a film structure of (L1H2L3H4L5H6) laminated in this order is continuously repeated. In the aforementioned structure, L1 is a low refractive index layer consisting of L and having the optical film thickness nLd1 satisfying 0.2×λ<=nLd1<=0.3×λ, H2 is a high refractive index layer consisting of H and having the optical film thickness nHd2 satisfying 0.025×λ<=nHd2<=0.05×λ, L3 is a low refractive index layer consisting of L and having the optical film thickness nLd3 satisfying 0.25×λ<=nLd3<=0.05×λ, H4 is a high refractive index layer consisting of H and having the optical film thickness nHd4 satisfying 0.2×λ<=nHd4<=0.3×λ, L5 is a low refractive index layer consisting of L and having the optical film thickness nLd5 satisfying 0.025×λ<=nLd5<=0.05×λ, and H6 is a high refractive index layer consisting of H and having the optical film thickness nHd6 satisfying 0.025×λ<=nHd6<=0.05×λ.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、特定の波長光を透
過し、特定の波長の光を透過させない光学特性を有した
多層膜フィルターに関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer filter having an optical property of transmitting light of a specific wavelength and not transmitting light of a specific wavelength.

【0002】[0002]

【従来の技術】カメラや顕微鏡、内視鏡をはじめとする
光学系では、特定の波長の光を取り出したり、光学的に
有害な波長の光をカットする目的で、特定の光を透過
し、特定の光を透過させない特性を有した光学的フィル
ターが用いられている。その一例として、人間の目には
感度がないが半導体撮像素子には大きな感度を有してい
る赤外線をカットするために、光学系の中に赤外線カッ
トフィルターを用いることがなされている。この場合、
透過させる波長と透過を阻止する波長とが近い場合や、
阻止する波長の透過率を非常に低く押さえる場合は、染
料や顔料を使用したフィルターでは十分な光学特性が得
られないため、屈折率の異なる2種以上の物質を多層に
積層したいわゆる多層膜フィルターが光学系の中に用い
られる。
2. Description of the Related Art Optical systems such as cameras, microscopes, and endoscopes transmit specific light for the purpose of extracting light of a specific wavelength or cutting light of an optically harmful wavelength. An optical filter having a property of not transmitting specific light is used. As one example, an infrared cut filter is used in an optical system to cut off infrared light which is insensitive to human eyes but has high sensitivity to a semiconductor imaging device. in this case,
When the wavelength to transmit and the wavelength to block transmission are close,
When the transmittance of the wavelength to be blocked is suppressed to a very low level, a filter using a dye or a pigment cannot provide sufficient optical characteristics. Therefore, a so-called multilayer filter in which two or more substances having different refractive indexes are laminated in a multilayer. Are used in the optical system.

【0003】多層膜フィルターは一般に、設計波長λの
1/4の光学的膜厚を基本膜厚とし、この基本膜厚の高
屈折率物質と低屈折率物質とを積層し、さらに光学特性
調整用の調整層を加えた膜構成となっている。この内、
特開平6−109921号公報には、成膜後の膜の基板
からの剥離や亀裂を防止する目的で、調整層を除く部分
を構成する高屈折率物質の光学的膜厚を0.1〜0.2
λ、低屈折率物質の光学的膜厚を0.3〜0.5λとす
ることが記載されている。
[0003] In general, a multilayer filter has an optical film thickness of 1/4 of the design wavelength λ as a basic film thickness, a high-refractive-index material and a low-refractive-index material of this basic film thickness are laminated, and the optical characteristics are further adjusted. The structure is such that an adjustment layer is added. Of these,
JP-A-6-109921 discloses that the optical film thickness of a high refractive index material constituting a portion excluding an adjustment layer is 0.1 to 0.1 mm in order to prevent peeling and cracking of a film after film formation from a substrate. 0.2
λ, the optical film thickness of the low refractive index substance is set to 0.3 to 0.5λ.

【0004】[0004]

【発明が解決しようとする課題】しかし、設計波長λの
1/4の光学的膜厚を積層した多層膜では、膜材料の屈
折率及び高屈折率物質の屈折率と低屈折率物質と屈折率
の差によって、ほぼ阻止域の帯域幅が決定される。この
阻止域は、設計波長λを中心に現れ、基本となる高屈折
率物質と低屈折率物質との屈折率の差が大きいほど、阻
止域の帯域幅も大きくなる。
However, in a multilayer film having an optical thickness of 1 / of the design wavelength λ, the refractive index of the film material, the refractive index of the high refractive index material, the refractive index of the low refractive index material, The difference in rates determines the bandwidth of the stopband approximately. This stop band appears around the design wavelength λ. The larger the difference between the refractive indices of the basic high refractive index material and the low refractive index material, the larger the bandwidth of the stop band.

【0005】高屈折率物質と低屈折率物質の屈折率をそ
れぞれn,nとすると、一般に、阻止域の中心波長
に関する全幅の設計波長λに対する割合は、近似的に数
1で与えられることが知られている。
[0005] High refractive index material and the refractive index of the low refractive index material each n H, When n L, in general, the ratio to the design wavelength λ of the total width about the central wavelength of the stopband is given approximately by the number 1 It is known.

【0006】[0006]

【数1】 (Equation 1)

【0007】すなわち、阻止域の帯域幅を変えるには、
基本的に高屈折率物質と低屈折率物質の屈折率の差を変
える、すなわち膜の材質を変える必要がある。しかし、
膜の材質は一般に屈折率だけでなく、膜の強度や耐久
性、安定性、生産性などを考慮して決定されるため、必
要な屈折率の材質が使用できない場合がある問題点を有
している。
That is, to change the bandwidth of the stop band,
Basically, it is necessary to change the difference between the refractive indices of the high refractive index substance and the low refractive index substance, that is, to change the material of the film. But,
In general, the material of the film is determined not only by the refractive index but also by considering the strength, durability, stability, and productivity of the film. ing.

【0008】また、設計波長λに現れる阻止域の他に、
設計波長がλ/3の場合にも副次的に阻止域が形成され
る。これは、3次の阻止帯などと呼ばれる。このため、
例えば赤外線をカットして可視域全域で高い透過率が必
要とされる場合、副次的な阻止域が可視域にかかってし
まって良好な特性が得られない問題点も有している。こ
の3次の阻止帯による問題点は、高屈折率物質の光学的
膜厚を0.1〜0.2λ、低屈折率物質の光学的膜厚を
0.3〜0.5λなどとして、基本周期の膜厚を変化さ
せて、副次的な阻止域の位置を変えても現れるものであ
る。
In addition to the stop band appearing at the design wavelength λ,
Even when the design wavelength is λ / 3, a stop band is formed secondarily. This is called a third-order stop band or the like. For this reason,
For example, when high transmittance is required in the entire visible region by cutting infrared rays, there is also a problem that a secondary blocking region covers the visible region and good characteristics cannot be obtained. The problem with the third-order stop band is that the optical film thickness of the high-refractive-index material is 0.1 to 0.2λ and the optical film thickness of the low-refractive-index material is 0.3 to 0.5λ. This appears even when the position of the secondary blocking zone is changed by changing the film thickness of the period.

【0009】本発明は、このような問題点に鑑み、膜材
料を変えなくても阻止域の幅を変えることができる、或
いは高い透過率が必要な波長の範囲において阻止域が現
れないという光学的に有効な多層膜フィルターを提供す
ることを目的とする。
In view of the above problems, the present invention provides an optical system in which the width of the stop band can be changed without changing the film material, or the stop band does not appear in the wavelength range where high transmittance is required. It is an object of the present invention to provide an effective multilayer filter.

【0010】[0010]

【課題を解決するための手段】上記目的を達成するた
め、請求項1の発明は、屈折率の異なる2種類以上の物
質を積層してなる多層膜フィルターであって、高屈折率
物質をH、低屈折率物質をL、設計波長をλとした場
合、Lからなる光学的膜厚nが0.2×λ≦n
≦0.3×λの低屈折率層L1Hからなる光学的膜
厚nが0.025×λ≦n≦0.05×λ
の低屈折率層H2Lからなる光学的膜厚nが0.
025×λ≦n≦0.05×λの低屈折率層L3
Hからなる光学的膜厚nが0.2×λ≦n
≦0.3×λの低屈折率層H4Lからなる光学的膜厚n
が0.025×λ≦n≦0.05×λの低
屈折率層L5Hからなる光学的膜厚nが0.02
5×λ≦n≦0.05×λの低屈折率層H6から
なり、(L1H2L3H4L5H6)の順で並んだ膜構
成が連続して複数回繰り返される部分を有することを特
徴とする。
In order to achieve the above object, the invention of claim 1 is a multilayer filter in which two or more materials having different refractive indices are laminated, wherein a high refractive index material is H. When the low-refractive-index substance is L and the design wavelength is λ, the optical film thickness n L d 1 of L is 0.2 × λ ≦ n L.
d 1 ≦ 0.3 optical thickness n H d 2 composed of a low refractive index layer L1H of × lambda is 0.025 × λ ≦ n H d 2 ≦ 0.05 × λ
The optical film thickness n L d 3 made of the low refractive index layer H2L of 0.
025 × λ ≦ n L d 3 ≦ 0.05 × λ Low refractive index layer L3
Optical film thickness n H d 4 is 0.2 × λ ≦ n H d 4 consisting of H
Optical film thickness n composed of low refractive index layer H4L of ≦ 0.3 × λ
Optical film thickness n H d 6 where L d 5 is made of a low refractive index layer L5H of 0.025 × λ ≦ n L d 5 ≦ 0.05 × λ 0.02
5 × consists λ ≦ n H d 6 ≦ 0.05 × low refractive index layer of lambda H6, and having a portion which film structure arranged in this order is repeated several times in succession the (L1H2L3H4L5H6).

【0011】すなわち、このような多層膜フィルター
は、L1からH6までの構成を1組とし、この上に少な
くとも1組を積み重ねた2組以上を有する多層膜とする
ことによって多層膜フィルターを構成するものである。
この多層膜フィルターでは、基板側から順次に積層して
も良く、空気と接する側から順次に積層しても良い。こ
こで、nは高屈折率物質の屈折率、nは低屈折率物
質の屈折率、dは各物質の膜厚である。
That is, in such a multilayer filter, a multilayer filter having two or more sets obtained by stacking at least one set on L1 to H6 is formed as one set. Things.
In this multilayer filter, the layers may be sequentially stacked from the substrate side, or may be sequentially stacked from the side in contact with air. Here, n H is the refractive index of the high refractive index material, n L is the refractive index of the low refractive index material, d is the thickness of each substance.

【0012】以上の繰り返し層の他に、光学特性を調整
するための調整層を設けても良いが、調整層はなくても
良い。また、調整層には、繰り返しに用いたH,L以外
の物質を用いてもかまわない。
In addition to the above-mentioned repeating layer, an adjusting layer for adjusting optical characteristics may be provided, but the adjusting layer may not be provided. In addition, a substance other than H and L used repeatedly may be used for the adjustment layer.

【0013】以上の膜構成では、L1の半分の膜厚
(0.1×λ≦ndL≦0.15×λ)の低屈折率層
をL1′として、(L1′H2L3H4L5H6L
1′)のようにしても良い。このL1′を有する構成を
用いると、低屈折率層L1′間の周期構造をより対称に
近いかたちで表すことができる。特に、H2=H6かつ
L3=L5となる場合には、周期構造は対称になる。た
だし、H2=H6あるいはL3=L5とすべき必然性は
ない。
In the above film configuration, a low refractive index layer having a thickness (0.1 × λ ≦ ndL 1 ≦ 0.15 × λ) that is half the thickness of L1 is defined as L1 ′ and (L1′H2L3H4L5H6L
1 '). When the configuration having L1 'is used, the periodic structure between the low-refractive-index layers L1' can be expressed in a more symmetrical manner. In particular, when H2 = H6 and L3 = L5, the periodic structure becomes symmetric. However, it is not necessary that H2 = H6 or L3 = L5.

【0014】本発明に用いる高屈折率物質Hとしては、
TiO、Ta、Nb、ZrO、HfO
、Y、Al、WO、MoO、低屈折
率物質Lとしては、SiO,MgFなどのような酸
化物やフッ化物を使用するのが生産性などの観点から好
ましいが、これらの限定されるものではない。
The high refractive index substance H used in the present invention includes:
TiO 2 , Ta 2 O 5 , Nb 2 O 5 , ZrO 2 , HfO
2 , Y 2 O 3 , Al 2 O 3 , WO 3 , MoO 3 , and oxides and fluorides such as SiO 2 and MgF 2 are used as the low-refractive-index substance L from the viewpoint of productivity and the like. However, these are not limited.

【0015】以上の本発明では、従来のλ/4ないしそ
の近傍の膜厚の高屈折率物質Hからなる高屈折率層と、
低屈折率物質Lからなる低屈折率層との間に、0.02
5〜0.05λという非常に薄い膜厚の層を2層ずつ挟
んでいる。これは、(L1H2L3H4L5H6)とい
う系を考えたとき、例えばL1と(H2L3H4L5H
6)のふたつに分けるとすると、H4という層が、両側
にH2L3及びL5H6という平均ではH4よりも屈折
率の低い層に囲まれていることになる。また、(H2L
3H4L5H6)という群全体をひとつの層と考える
と、H4よりもやや低い屈折率と等価な層であるといえ
る。このことにより、高屈折率物質と低屈折率物質の見
かけの屈折率の差を任意に小さくすることが可能とな
り、阻止域の帯域幅を任意に調整することができる。さ
らに、このときのH2L3及びL5H6の膜厚を調整す
ることにより、λ/3の波長に形成される副次的な阻止
域をなくすことができる。
In the present invention described above, the conventional high-refractive-index layer made of the high-refractive-index material H having a thickness of λ / 4 or near the same is provided;
0.02 between the low refractive index layer made of the low refractive index material L
Two layers each having a very thin film thickness of 5 to 0.05λ are sandwiched. This is because when considering the system (L1H2L3H4L5H6), for example, L1 and (H2L3H4L5H)
6), the layer H4 is surrounded on both sides by layers H2L3 and L5H6 having an average refractive index lower than that of H4. Also, (H2L
If the entire group of 3H4L5H6) is considered as one layer, it can be said that it is a layer equivalent to a refractive index slightly lower than H4. This makes it possible to arbitrarily reduce the difference between the apparent refractive indices of the high-refractive-index substance and the low-refractive-index substance, and arbitrarily adjust the bandwidth of the stop band. Further, by adjusting the thicknesses of H2L3 and L5H6 at this time, it is possible to eliminate a secondary stop band formed at a wavelength of λ / 3.

【0016】[0016]

【発明の実施の形態】(実施の形態1)この実施の形態
では、基板としての屈折率1.52のガラス製レンズの
表面に73層の赤外線カットフィルターを設けたもので
ある。成膜は、ガラス製レンズを真空槽に入れ、1×1
−4Paまで排気した後、レンズの表面上に電子ビー
ム蒸着法によって合計73層成膜することによって行っ
た。
(Embodiment 1) In this embodiment, a 73-layer infrared cut filter is provided on the surface of a glass lens having a refractive index of 1.52 as a substrate. For film formation, put a glass lens in a vacuum chamber and put 1 × 1
0 -4 was evacuated to Pa, it was carried out by summing 73 layer deposition by electron beam evaporation on the surface of the lens.

【0017】かかる成膜では、高屈折率物質H(屈折率
)としてTiOを、低屈折率物質L(屈折率
)としてSiOを用い、基板側から膜の厚さdを
以下の数値のように定め、L1層としてnd=0.2
5×λ、H2層としてnd=0.034×λ、H3層
としてnd=0.034×λ、L4層としてnd=
0.25×λ、L5層としてnd=0.034×λ、
H6層としてnd=0.034×λなる光学的膜厚を
12回繰り返して成膜し、その後、最後に調整層として
L=0.125×λを成膜した。このときの設計波長λ
は1100nmである。
In this film formation, TiO 2 is used as the high refractive index substance H (refractive index n H ), and SiO 2 is used as the low refractive index substance L (refractive index n L ). Determined as the following numerical values, and n L d = 0.2 for the L1 layer
5 × λ, n H d = 0.034 × λ as H2 layer, n H d = 0.034 × λ as H3-layer, n H d as L4 layer =
0.25 × λ, n L d = 0.034 × λ as the L5 layer,
The optical film thickness comprising n H d = 0.034 × λ as H6 layers deposited by repeating 12 times, then finally was formed L = 0.125 × λ as the adjustment layer. The design wavelength λ at this time
Is 1100 nm.

【0018】以上のようにして作製された赤外線カット
フィルターの垂直入射光の400〜2000nmでの分
光反射率特性を測定した。この測定結果を図1に示す。
図1に示すように、このフィルターは1400nmを中
心とする波長の透過を阻止する赤外線カットフィルター
であり、可視域から波長が1000nmという波長域の
全域で透過率80%以上、500〜1000nmでは透
過率90%以上という良好な特性を得ることができた。
The spectral reflectance characteristics of the infrared cut filter manufactured as described above at 400 to 2,000 nm of the vertically incident light were measured. FIG. 1 shows the measurement results.
As shown in FIG. 1, this filter is an infrared cut filter that blocks transmission of a wavelength centered at 1400 nm, and has a transmittance of 80% or more in the entire wavelength range from the visible range to a wavelength of 1000 nm, and a transmittance of 500 to 1000 nm. Good characteristics of 90% or more could be obtained.

【0019】TiO及びSiOの屈折率は、それぞ
れ2.3及び1.46で設定してあるが、この実施の形
態では、赤外領域の阻止域の幅はSiOの屈折率を
1.46のままとした場合、TiOの屈折率が2.1
相当になっていることがわかる。また、屈折率2.1の
高屈折率の材料と屈折率1.46の低屈折率の材料とを
それぞれλ/4ずつ12回繰り返して成膜した場合に
は、460〜500nmに現れる阻止域がなく、可視域
全域で高い透過率を得ることができた。
Although the refractive indexes of TiO 2 and SiO 2 are set to 2.3 and 1.46, respectively, in this embodiment, the width of the blocking region in the infrared region is set so that the refractive index of SiO 2 is 1 .46, the refractive index of TiO 2 is 2.1.
It turns out that it is considerable. Further, when a high refractive index material having a refractive index of 2.1 and a low refractive index material having a refractive index of 1.46 are repeatedly formed 12 times each at λ / 4, a stop band appearing at 460 to 500 nm is formed. And a high transmittance could be obtained over the entire visible range.

【0020】(比較例1)この比較例では、実施の形態
1と同様の基板上に、同じく高屈折率物質HとしてTi
を、低屈折率物質LとしてSiOを用い、基板側
からL1層としてnd=0.25×λ、H2層として
d=0.25×λなる光学的膜厚を12回繰り返し
て成膜し、その後、最後に調整層として、低屈折率物質
からなるL25層としてnd=0.125×λを成膜
した。このときの設計波長λは1400nmである。
Comparative Example 1 In this comparative example, a high refractive index material H was formed on a substrate similar to that of the first embodiment.
O 2 is SiO 2 as the low-refractive-index substance L, and the optical film thickness of n L d = 0.25 × λ as the L1 layer and n H d = 0.25 × λ as the H2 layer is 12 from the substrate side. The film was repeatedly formed twice, and finally, as an adjustment layer, n L d = 0.125 × λ was formed as an L25 layer made of a low refractive index material. The design wavelength λ at this time is 1400 nm.

【0021】このようにして作製された赤外線カットフ
ィルターの垂直入射光の400〜2000nmでの分光
率特性を測定した結果を図2に示す。これは1400n
mを中心とする波長の透過を阻止するような赤外線カッ
トフィルターであり、実施の形態1と比較すると、赤外
域の阻止域の幅が広くなっているほか、460〜500
nmでほとんど光を透過していないことがわかる。この
比較例1との比較から、実施の形態1の多層膜フィルタ
ーは、優れた性能を有していることがわかる。
FIG. 2 shows the results of measuring the spectral characteristics of the infrared cut filter manufactured in this manner at 400 to 2,000 nm of the vertically incident light. This is 1400n
This is an infrared cut filter that blocks transmission of wavelengths centered at m. Compared with the first embodiment, the infrared cut filter has a wider blocking region in the infrared region, and has a wavelength of 460 to 500.
It can be seen that almost no light is transmitted in nm. From comparison with Comparative Example 1, it is understood that the multilayer filter of Embodiment 1 has excellent performance.

【0022】(実施の形態2〜8)実施の形態2〜8で
は、実施の形態1の膜の膜厚を表1に示すものに変更す
るものである。なお、表1において、例えば、基板側の
第1層として成膜した低屈折率物質Lからなる光学的膜
厚nd=0.25×λを0.25Lとして表してお
り、他の表示も同様である。
Embodiments 2 to 8 In Embodiments 2 to 8, the film thickness of the film of Embodiment 1 is changed to that shown in Table 1. In Table 1, for example, the optical film thickness n L d = 0.25 × λ made of the low-refractive-index substance L formed as the first layer on the substrate side is represented as 0.25 L. The same is true for

【0023】以上実施の形態2〜8の赤外線カットフィ
ルターの垂直入射光の400〜2000nmでの分光反
射率特性を測定した結果を図3〜図9に示す。図3は実
施の形態2に、図4は実施の形態3に、図4は実施の形
態3に、図5は実施の形態4に、図6は実施の形態5
に、図7は実施の形態6に、図8は実施の形態7に、図
9は実施の形態8に対応するものである。
FIGS. 3 to 9 show the results of measuring the spectral reflectance characteristics of the infrared cut filters according to Embodiments 2 to 8 at 400 to 2000 nm of the vertically incident light. FIG. 3 shows the second embodiment, FIG. 4 shows the third embodiment, FIG. 4 shows the third embodiment, FIG. 5 shows the fourth embodiment, and FIG. 6 shows the fifth embodiment.
FIG. 7 corresponds to the sixth embodiment, FIG. 8 corresponds to the seventh embodiment, and FIG. 9 corresponds to the eighth embodiment.

【0024】図3〜図9に示すように、いずれの実施の
形態も、波長1400nmを中心とする波長の透過を阻
止できる赤外線カットフィルターとなっている。従っ
て、実施の形態1と同様、可視域全域で高い透過率を得
ることが可能となっている。
As shown in FIGS. 3 to 9, each embodiment is an infrared cut filter capable of blocking transmission of a wavelength centered at 1400 nm. Therefore, as in the first embodiment, it is possible to obtain a high transmittance in the entire visible region.

【0025】(実施の形態9)この実施の形態では、実
施の形態1において設計波長1100nmであった設計
波長λを800nmにするとともに、波長が1000〜
1050nmを中心とする阻止域の透過率をさらに下げ
るため、具体的には実施の形態1での阻止域の透過率
0.1%を0.01%まで下げるため、繰り返し回数を
20回とした。また、基板側の第1層目をλ/8の膜厚
を有した屈折率1.6の中間屈折率物質(Al
とした。膜設計値を表1に示す。中間屈折率層を加える
ことによって、特に波長800nm〜500nmの範囲
における透過帯域での透過率のリップル(透過率の波う
ち)を減らすことができた。
(Embodiment 9) In this embodiment, the design wavelength λ, which was the design wavelength 1100 nm in the first embodiment, is changed to 800 nm, and the design wavelength
The number of repetitions was set to 20 in order to further reduce the transmittance in the stop region centered at 1050 nm, specifically, to reduce the transmittance in the stop region in Embodiment 1 from 0.1% to 0.01%. . The first layer on the substrate side is an intermediate refractive index material (Al 2 O 3 ) having a thickness of λ / 8 and a refractive index of 1.6.
And Table 1 shows the film design values. By adding the intermediate refractive index layer, it was possible to reduce the transmittance ripple (wavelength of the transmittance) particularly in the transmission band in the wavelength range of 800 nm to 500 nm.

【0026】すなわち、この実施の形態では、(0.1
25L 0.031H 0.0345L 0.25H
0.0345L 0.031H 0.125L)からな
るパターンを20回繰り返し、その中で基板に接する第
1層目の0.125Lのみを低屈折率物質から中間屈折
率物質に変更した構成とするものである。
That is, in this embodiment, (0.1
25L 0.031H 0.0345L 0.25H
(0.0345L 0.031H 0.125L) is repeated 20 times, in which only the first layer 0.125L in contact with the substrate is changed from a low refractive index material to an intermediate refractive index material. It is.

【0027】このようにして作製された赤外線カットフ
ィルターの垂直入射光の400〜1300nmでの分光
反射率特性を測定した結果を図10に示す。これは10
00〜1050nmを中心とする波長の透過を阻止でき
る赤外線カットフィルターである。従って、この実施の
形態では、実施の形態1と同様に、可視域全域で80%
以上、500〜700nmでは90%以上の高い透過率
を得ることが可能となっている。
FIG. 10 shows the results of measuring the spectral reflectance characteristics of the infrared cut filter manufactured as described above at 400 to 1300 nm of the vertically incident light. This is 10
An infrared cut filter that can block transmission of wavelengths centered on 00 to 1050 nm. Therefore, in this embodiment, as in the first embodiment, 80% over the entire visible range.
As described above, it is possible to obtain a high transmittance of 90% or more at 500 to 700 nm.

【0028】なお、本発明の各実施の形態では、いずれ
も光学的膜厚ndが0.05×λ以下の高屈折率物質ど
うし、あるいは低屈折率物質どうしの膜厚を同じとした
が、請求項に記載された光学的膜厚の範囲内であれば、
互いに同じ膜厚である必要はないものである。
In each of the embodiments of the present invention, the high refractive index material or the low refractive index material having an optical thickness nd of 0.05 × λ or less has the same thickness. Within the range of the optical film thickness described in the claims,
It is not necessary that they have the same thickness.

【0029】[0029]

【表1】 [Table 1]

【0030】[0030]

【発明の効果】以上説明したように、請求項1の発明に
よれば、高屈折率物質と低屈折率物質の見かけの屈折率
の差を任意に小さくすることが可能になり、多層膜フィ
ルターの阻止域の帯域幅を任意に調整するとが可能にな
る。また、、膜厚を最適化することにより、λ/3の波
長などに形成される副次的な阻止域をなくすことが可能
となる。
As described above, according to the first aspect of the invention, it is possible to arbitrarily reduce the difference between the apparent refractive indices of the high-refractive index substance and the low-refractive index substance. Can be adjusted arbitrarily. Further, by optimizing the film thickness, it is possible to eliminate a secondary stop band formed at a wavelength of λ / 3 or the like.

【図面の簡単な説明】[Brief description of the drawings]

【図1】実施の形態1の多層膜フィルターの分光反射率
特性図である。
FIG. 1 is a spectral reflectance characteristic diagram of a multilayer filter according to a first embodiment.

【図2】比較例1の多層膜フィルターの分光反射率特性
図である。
FIG. 2 is a spectral reflectance characteristic diagram of a multilayer filter of Comparative Example 1.

【図3】実施の形態2の多層膜フィルターの分光反射率
特性図である。
FIG. 3 is a spectral reflectance characteristic diagram of the multilayer filter according to the second embodiment.

【図4】実施の形態3の多層膜フィルターの分光反射率
特性図である。
FIG. 4 is a spectral reflectance characteristic diagram of a multilayer filter according to a third embodiment.

【図5】実施の形態4の多層膜フィルターの分光反射率
特性図である。
FIG. 5 is a spectral reflectance characteristic diagram of a multilayer filter according to a fourth embodiment.

【図6】実施の形態5の多層膜フィルターの分光反射率
特性図である。
FIG. 6 is a spectral reflectance characteristic diagram of the multilayer filter according to the fifth embodiment.

【図7】実施の形態6の多層膜フィルターの分光反射率
特性図である。
FIG. 7 is a spectral reflectance characteristic diagram of a multilayer filter according to a sixth embodiment.

【図8】実施の形態7の多層膜フィルターの分光反射率
特性図である。
FIG. 8 is a spectral reflectance characteristic diagram of the multilayer filter according to the seventh embodiment.

【図9】実施の形態8の多層膜フィルターの分光反射率
特性図である。
FIG. 9 is a spectral reflectance characteristic diagram of the multilayer filter according to the eighth embodiment.

【図10】実施の形態9の多層膜フィルターの分光反射
率特性図である。
FIG. 10 is a spectral reflectance characteristic diagram of the multilayer filter according to the ninth embodiment.

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 屈折率の異なる2種類以上の物質を積層
してなる多層膜フィルターであって、 高屈折率物質をH、低屈折率物質をL、設計波長をλと
した場合、 Lからなる光学的膜厚nが0.2×λ≦n
≦0.3×λの低屈折率層L1 Hからなる光学的膜厚nが0.025×λ≦n
≦0.05×λの低屈折率層H2 Lからなる光学的膜厚nが0.025×λ≦n
≦0.05×λの低屈折率層L3 Hからなる光学的膜厚nが0.2×λ≦n
≦0.3×λの低屈折率層H4 Lからなる光学的膜厚nが0.025×λ≦n
≦0.05×λの低屈折率層L5 Hからなる光学的膜厚nが0.025×λ≦n
≦0.05×λの低屈折率層H6 からなり、(L1H2L3H4L5H6)の順で並んだ
膜構成が連続して複数回繰り返される部分を有すること
を特徴とする多層膜フィルター。
1. A multilayer filter comprising two or more kinds of materials having different refractive indices, wherein a high refractive index material is H, a low refractive index material is L, and a design wavelength is λ. Optical film thickness n L d 1 is 0.2 × λ ≦ n L d 1
≦ 0.3 optical film thickness n H d 2 composed of a low refractive index layer L1 H of × lambda is 0.025 × λ ≦ n H
The optical film thickness n L d 3 of the low refractive index layer H 2 L with d 2 ≦ 0.05 × λ is 0.025 × λ ≦ n L
d 3 ≦ 0.05 × optical thickness made of a low refractive index layer L3 H of lambda n H d 4 is 0.2 × λ ≦ n H d 4
≦ 0.3 × optical thickness n L d 5 composed of a low refractive index layer H4 L of lambda is 0.025 × λ ≦ n L
d 5 ≦ 0.05 optical thickness n H d 6 composed of a low refractive index layer L5 H of × lambda is 0.025 × λ ≦ n H
A multilayer filter comprising a low refractive index layer H6 of d 6 ≦ 0.05 × λ, and having a portion in which a film configuration arranged in the order of (L1H2L3H4L5H6) is continuously repeated a plurality of times.
JP11136429A 1999-05-17 1999-05-17 Multilayered film filter Withdrawn JP2000329933A (en)

Priority Applications (1)

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Publication Number Publication Date
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Application Number Title Priority Date Filing Date
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Country Link
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