JP2001004840A - Polarizing beam splitter - Google Patents
Polarizing beam splitterInfo
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- JP2001004840A JP2001004840A JP11176065A JP17606599A JP2001004840A JP 2001004840 A JP2001004840 A JP 2001004840A JP 11176065 A JP11176065 A JP 11176065A JP 17606599 A JP17606599 A JP 17606599A JP 2001004840 A JP2001004840 A JP 2001004840A
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- thin film
- layer
- film layer
- optical
- beam splitter
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、光学系の集光光束
中又は発散光束中において出射光と入射光を分岐する際
に、透過光及び反射光を分離する偏光分離特性を有する
偏光ビームスプリッタに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing beam splitter having a polarization splitting characteristic for separating transmitted light and reflected light when splitting outgoing light and incident light in a converged light beam or a divergent light beam of an optical system. It is about.
【０００２】[0002]
【従来の技術】従来、平行光束中において使用される偏
光ビームスプリッタとして、相対的に高屈折率物質から
成る薄膜層と相対的に低屈折率物質から成る薄膜層と
を、交互に繰り返して光透過性基板の接合面に形成した
誘電体多層膜を、偏光分離面として使用しているものが
知られている。2. Description of the Related Art Conventionally, as a polarizing beam splitter used in a parallel light beam, a thin film layer made of a material having a relatively high refractive index and a thin film layer made of a material having a relatively low refractive index are alternately repeated. It is known that a dielectric multilayer film formed on a bonding surface of a transparent substrate is used as a polarization splitting surface.
【０００３】偏光ビームスプリッタを構成する光透過性
基板の材質をＧ、相対的に高屈折率物質から成る薄膜層
をＨ、相対的に低屈折率物質から成る薄膜層をＬとす
る。そして、光透過性基板の材質Ｇ、薄膜層Ｈ、薄膜層
Ｌの屈折率、薄膜層の光学的膜厚を、それぞれｎg 、ｎ
h 、ｎl 、ｎd とする。ここで、これらのｎg 、ｎl 、
ｎd は設計基準波長７８０ｎｍにおける値とする。The material of the light-transmitting substrate constituting the polarizing beam splitter is G, the thin film layer made of a material having a relatively high refractive index is H, and the thin film layer made of a material having a relatively low refractive index is L. The material G of the light-transmitting substrate, the refractive indices of the thin film layers H and L, and the optical film thicknesses of the thin film layers are respectively ng and n.
h, nl, and nd. Where ng, nl,
nd is a value at a design reference wavelength of 780 nm.
【０００４】一般的に従来から使用されている偏光ビー
ムスプリッタの偏光分離面に形成された誘電体多層膜
は、光の進行順にＧ／Ｈ／Ｌ／・・・／Ｈ／Ｌ／Ｈの総
数１７層の薄膜交互層で構成されており、ｎg 、ｎh 、
ｎl 、ｎd は次の通りである。In general, a dielectric multilayer film formed on a polarization splitting surface of a conventionally used polarizing beam splitter has a total number of G / H / L /... / H / L / H in the order of light traveling. It consists of 17 thin film alternating layers, ng, nh,
nl and nd are as follows.
【０００５】Ｇ；ｎg ＝1 ．７４（Ｓ−ＴＩＨ４；株式
会社ＯＨＡＲＡ製） Ｈ；ＴｉＯ2 、ｎh ＝２．２６，ｎd ＝２２３ｎｍ Ｌ；ＳｉＯ2 、ｎ1 ＝１．５，ｎd ＝２２３ｎｍG; ng = 1. 74 (S-TIH4; Ltd. OHARA) H; TiO 2, nh = 2.26, nd = 223nm L; SiO 2, n1 = 1.5, nd = 223nm
【０００６】このようにして、各界面でブリュースタ角
の条件を満足する薄膜層Ｈと薄膜層Ｌの光学的膜厚の比
を１：１として構成し、この誘電体多層膜を蒸着した光
透過性基板を、設計基準波長７８０ｎｍにおける屈折率
ｎb ＝１．５６の光透過性接着剤によって、同一材質の
Ｓ−ＴＩＨ４から成る光透過性基板を接合して、偏光ビ
ームスプリッタを形成している。Thus, the ratio of the optical film thickness of the thin film layer H to the thin film layer L satisfying the Brewster angle condition at each interface is set to 1: 1. A polarizing beam splitter is formed by bonding a transparent substrate made of S-TIH4 of the same material with a transparent adhesive having a refractive index nb = 1.56 at a design reference wavelength of 780 nm. .
【０００７】図８はこの偏光ビームスプリッタの偏光分
離面に、平行光束が入射角４５°で入射した時の偏光分
離特性の波長依存性を示し、Ｓ偏光成分の反射率をＲ
Ｓ、Ｐ偏光成分の透過率をＴＰで表している。波長５１
０〜８２０ｎｍまでの範囲においては、これら反射率Ｒ
Ｓと透過率ＴＰとが共に１００％に近く、極めて良好な
偏光分離特性を示す偏光ビームスプリッタとなってい
る。このように従来例の偏光ビームスプリッタは、偏光
分離面に対して平行光束を入射角４５°で入射させたと
きに、最も効率の良い偏光分離特性を示すものである。FIG. 8 shows the wavelength dependence of the polarization splitting characteristic when a parallel light beam is incident on the polarization splitting surface of the polarizing beam splitter at an incident angle of 45 °.
The transmittance of the S and P polarization components is represented by TP. Wavelength 51
In the range from 0 to 820 nm, the reflectance R
Both S and the transmittance TP are close to 100%, and the polarizing beam splitter exhibits extremely good polarization separation characteristics. As described above, the conventional polarization beam splitter exhibits the most efficient polarization separation characteristics when a parallel light beam is incident on the polarization separation surface at an incident angle of 45 °.
【０００８】図９は光学装置を小型化又は簡素化する必
要性からアフォーカル系を廃止して、Ｆナンバ＝２．０
となる光学系の集光光束中に偏光ビームスプリッタを配
置した場合について、波長７８０ｎｍにおける偏光分離
特性の角度依存性を示している。ここで、横軸の角度は
偏光ビームスプリッタのガラス中における値で表してお
り、Ｆナンバが２．０に相当する光線入射角は、４５°
を中心として３７°〜５３°までの範囲である。FIG. 9 shows that the afocal system is abolished due to the necessity of miniaturizing or simplifying the optical device, and the F number is 2.0.
In the case where a polarization beam splitter is arranged in the condensed light beam of the optical system, the angle dependence of the polarization separation characteristic at a wavelength of 780 nm is shown. Here, the angle on the horizontal axis is represented by a value in the glass of the polarizing beam splitter, and the light incident angle corresponding to an F number of 2.0 is 45 °.
From 37 ° to 53 °.
【０００９】偏光分離面への入射角４５°を中心として
−４゜よりも小傾角側の透過光と、＋４°よりも大傾角
側の透過光は、共にＰ偏光成分の透過率ＴＰの非対称性
が著しい。同様に、入射角４５°を中心に−７°よりも
小傾角側の反射光と、＋７°よりも大傾角側の反射光
も、共にＳ偏光成分の反射率ＲＳの非対称性が著しい。
このように、従来例の偏光ビームスプリッタの偏光分離
特性は非対称な角度依存性を有している。[0009] Both the transmitted light on the tilt angle side smaller than -4 ° and the transmitted light on the tilt angle side larger than + 4 ° around the incident angle of 45 ° to the polarization splitting surface are asymmetrical in the transmittance TP of the P-polarized component. The nature is remarkable. Similarly, both the reflected light on the tilt angle side smaller than -7 ° and the reflected light on the tilt side larger than + 7 ° centered on the incident angle of 45 ° have remarkable asymmetry of the reflectance RS of the S-polarized component.
As described above, the polarization splitting characteristic of the conventional polarization beam splitter has an asymmetric angle dependence.
【００１０】従来、光ピックアップ装置等のように光軸
方向補正機構を備える投受光装置においては、位置検出
用受光素子として４分割センサを利用することが多い。
このような受光素子を用いる場合には、受光面上の受光
ビームスポットが小さ過ぎると、４分割センサの無感度
領域である十字状分離帯にビームスポットが落ち込んで
しまい、位置検出出力が無くなるという現象を起こした
り、十字状分離帯を横切る際に検出出力が急激に変化し
て、光軸方向制御が不安定になるという現象を起こす。Conventionally, in a light emitting and receiving device having an optical axis direction correcting mechanism, such as an optical pickup device, a four-divided sensor is often used as a position detecting light receiving element.
When such a light receiving element is used, if the light receiving beam spot on the light receiving surface is too small, the beam spot falls into the cross-shaped separation band, which is the insensitive area of the four-divided sensor, and the position detection output is lost. When the phenomenon occurs or the detection output suddenly changes when crossing the cross-shaped separation band, the phenomenon that the optical axis direction control becomes unstable is caused.
【００１１】一方、受光ビームスポットが大き過ぎると
感度が悪くなり、高周波成分の揺れに対して、光軸方向
制御が追随できなくなる。従って、このような光軸方向
補正制御における不都合を解決するために、集光点より
もデフォーカスした位置に４分割センサの受光面位置を
設定して、受光ビームスポットには適切な広がりを持た
せるのが一般的である。On the other hand, if the light receiving beam spot is too large, the sensitivity becomes worse, and the optical axis direction control cannot follow the fluctuation of the high frequency component. Therefore, in order to solve such inconvenience in the optical axis direction correction control, the light receiving surface position of the four-divided sensor is set at a position defocused from the converging point, and the light receiving beam spot has an appropriate spread. It is common to make it.
【００１２】[0012]
【発明が解決しようとする課題】しかしながら、上述の
従来例の集光光束中に偏光ビームスプリッタを使用した
光学装置では、４分割センサの受光面上で非対称な光強
度分布の受光ビームスポットを受光することになり、光
強度分布が非対称な場合は、受光ビームスポットが十字
状分離帯を横切る方向によって光軸ずれ検出感度が異な
り、光軸方向制御の不安定要因となる。However, in the above-described optical device using a polarizing beam splitter in the condensed light beam of the prior art, a light receiving beam spot having an asymmetric light intensity distribution is received on the light receiving surface of the four-divided sensor. Therefore, when the light intensity distribution is asymmetric, the detection sensitivity of the optical axis shift differs depending on the direction in which the light receiving beam spot crosses the cross-shaped separation zone, which becomes an unstable factor of the optical axis direction control.
【００１３】また、装置を組み立てる際に、位置検出用
光学系の光軸と投光光学系の光軸との光軸調整を行うと
きに、光学装置の前方に配置した反射工具を用いて、装
置自身から投影された光束の反射光を利用する方法が一
般に採用されている。このような光軸調整を行う際に、
投光光に光強度分布に非対称性があると、組立調整時の
光軸と実使用時の光軸とが異なり、これが位置検出誤差
となって光軸調整誤差の原因となる。Further, when assembling the apparatus, when adjusting the optical axes of the optical axis of the position detecting optical system and the optical axis of the light projecting optical system, a reflecting tool disposed in front of the optical apparatus is used. A method utilizing reflected light of a light beam projected from the device itself is generally adopted. When performing such optical axis adjustment,
If the projected light has asymmetry in the light intensity distribution, the optical axis at the time of assembly adjustment differs from the optical axis at the time of actual use, and this becomes a position detection error and causes an optical axis adjustment error.
【００１４】本発明の目的は、上述の問題点を解消し、
光入射角度依存性を軽減して非対称性が少ない極めて効
率の良い偏光分離特性を有する偏光ビームスプリッタを
提供することにある。An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a polarization beam splitter having extremely efficient polarization splitting characteristics with less asymmetry by reducing the dependence on the light incident angle.
【００１５】[0015]
【課題を解決するための手段】上記目的を達成するため
の本発明に係る偏光ビームスプリッタは、相対的に高屈
折率物質から成る薄膜層Ｈと相対的に低屈折率物質から
成る薄膜層Ｌとを交互に繰り返して構成する誘電体多層
膜を、２つの光透過性基板の接合面に形成した偏光ビー
ムスプリッタにおいて、前記誘電体多層膜は、膜構成が
Ｈ／Ｌ／Ｈ／Ｌ／Ｈである第１の積層と、膜構成がＨ／
Ｌ／Ｈ／Ｌ／Ｈである第２の積層とを含み、前記第１の
積層を構成する薄膜層Ｈ及び薄膜層Ｌの光学的膜厚の平
均値をそれぞれ〈Ｈ１〉及び〈Ｌ１〉とし、前記第２の
積層を構成する薄膜層Ｈ及び薄膜層Ｌの光学的膜厚の平
均値をそれぞれ〈Ｈ２〉及び〈Ｌ２〉とし、前記平均値
〈Ｈ１〉と〈Ｌ１〉の内の小さい方を分母とする平均値
〈Ｈ１〉と〈Ｌ１〉の比をＲ１とし、前記平均値〈Ｈ
２〉と〈Ｌ２〉の内の小さい方を分母とする平均値〈Ｈ
２〉と〈Ｌ２〉の比をＲ２として、これらの比Ｒ１と比
Ｒ２の内の小さい方をＱ１、大きい方をＱ２とし、ｍを
１〜３までの整数、ｎを１〜４までの整数とするとき
に、次式を満足することを特徴とする。In order to achieve the above object, a polarizing beam splitter according to the present invention comprises a thin film layer H made of a material having a relatively high refractive index and a thin film layer L made of a material having a relatively low refractive index. In a polarizing beam splitter in which a dielectric multilayer film formed by alternately repeating the above is formed on the joining surface of two light-transmitting substrates, wherein the dielectric multilayer film has a film configuration of H / L / H / L / H. And the film configuration is H /
L / H / L / H, and mean values of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the first stack are <H1> and <L1>, respectively. The average values of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the second stack are <H2> and <L2>, respectively, and the smaller one of the average values <H1> and <L1> Is the denominator, the ratio of the average value <H1> to <L1> is R1, and the average value <H
2> and <L2>, the average value <H using the smaller one as the denominator
The ratio between 2> and <L2> is R2, the smaller one of these ratios R1 and R2 is Q1, the larger is Q2, m is an integer from 1 to 3, and n is an integer from 1 to 4. Where the following equation is satisfied.
【００１６】０. ９５ｍ≦Ｑ１≦１. ２ｍ ０. ９（ｍ＋ｎ）≦Ｑ２≦１．４（ｍ＋ｎ） ２≦ｍ＋ｎ≦５0.95m ≦ Q1 ≦ 1.2m 0.9 (m + n) ≦ Q2 ≦ 1.4 (m + n) 2 ≦ m + n ≦ 5
【００１７】[0017]
【発明の実施の形態】本発明を図１〜図７に図示の実施
例に基づいて詳細に説明する。図１は偏光ビームスプリ
ッタの構成図を示し、三角柱状の光透過性基板１の接合
面に、誘電体多層膜２を真空蒸着により形成した後に、
同形の三角柱状の光透過性基板３を光透過性接着剤によ
り接合して、立方体形状の偏光ビームスプリッタが構成
されている。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 shows a configuration diagram of a polarization beam splitter. After a dielectric multilayer film 2 is formed on a bonding surface of a triangular prism-shaped light transmitting substrate 1 by vacuum evaporation,
A triangular prism-shaped light transmitting substrate 3 is joined by a light transmitting adhesive to form a cubic polarization beam splitter.
【００１８】この偏光ビームスプリッタを光学系中に配
置すると、入射光束Ｉの中心光線である主光線が、偏光
ビームスプリッタの基板１の光入射面に対して垂直に入
射し、誘電体多層膜２の偏光分離面に対しては４５°で
入射して、一部の光成分が透過光Ｔとして誘電体多層膜
２を透過し、残りの光成分が反射光Ｒとして誘電体多層
膜２で反射される。When this polarizing beam splitter is arranged in an optical system, the principal ray, which is the central ray of the incident light beam I, is perpendicularly incident on the light incident surface of the substrate 1 of the polarizing beam splitter, and the dielectric multilayer film 2 is formed. Incident on the polarization separation surface at 45 °, a part of the light component is transmitted through the dielectric multilayer film 2 as transmitted light T, and the remaining light component is reflected by the dielectric multilayer film 2 as reflected light R. Is done.
【００１９】本実施例の誘電体多層膜２は、薄膜層Ｈ及
び薄膜層Ｌの屈折率をそれぞれｎh及びｎl とし、光透
過性基板１、３の材質Ｇの屈折率をｎg とし、入射光束
Ｉの中心光線と偏光分離面との成す角をθとしたとき
に、入射光束Ｉの中心入射光束において、最も効率の良
い偏光分離特性とするために、ブリュースタ角の条件を
満たす角度θは次の条件式を満足する。 ０. ９≦ｎh ・ｎl ／{(ｓｉｎθ）・ｎg ・( ｎh 2 ＋
ｎl 2)1/2}≦１．１In the dielectric multilayer film 2 of this embodiment, the refractive indices of the thin film layers H and L are nh and nl, respectively, the refractive index of the material G of the light transmitting substrates 1 and 3 is ng, and the incident light flux is Assuming that the angle formed between the central ray of I and the polarization splitting plane is θ, the angle θ that satisfies the Brewster angle condition in the center incident luminous flux of the incident luminous flux I is to obtain the most efficient polarization splitting characteristic. The following conditional expression is satisfied. 0.9 ≦ nh · nl / {(sin θ) · ng · (nh 2 +
nl 2 ) 1/2 } ≦ 1.1
【００２０】ここで、入射角θを４５°として、次の条
件式を満足するように諸元ｎh 、ｎl 、ｎg を設定して
いる。ただし、諸元ｎh 、ｎl 、ｎg は設計基準波長７
８０ｎｍにおける値である。Here, assuming that the incident angle θ is 45 °, the specifications nh, nl, and ng are set so as to satisfy the following conditional expression. However, the specifications nh, nl, and ng are the design reference wavelength 7
It is a value at 80 nm.
【００２１】０．４≦ｎh 2 ・ｎl 2 ／［ｎg 2 ・{(ｎ
h )2＋（ｎl )2}]≦０. ６ ここで、諸元ｎh 、ｎl 、ｎg の値は次に示す通りであ
る。0.4 ≦ nh 2 · nl 2 / [ng 2 · {(n
h) 2 + (nl) 2 }] ≦ 0.6 Here, the values of the specifications nh, nl, and ng are as follows.
【００２２】Ｇ：ｎg ＝１．７４（Ｓ−ＴＩＨ４：株式
会社ＯＨＡＲＡ製） Ｈ：ＴｉＯ2 、ｎh ＝２．２６ Ｌ：ＳｉＯ2 、ｎｌ＝１．４５G: ng = 1.74 (S-TIH4: manufactured by OHARA Co., Ltd.) H: TiO 2 , nh = 2.26 L: SiO 2 , nl = 1.45
【００２３】本発明の偏光ビームスプリッタは、Ｐ偏光
成分とＳ偏光成分に対して、共に最も効率の良い偏光分
離特性とするために、相対的に高屈折率物質から成る薄
膜層Ｈと相対的に低屈折率物質から成る薄膜層Ｌとを交
互に繰り返し、全薄膜層の開始層と最終層とを共に高屈
折率物質から成る薄膜層Ｈで誘電体多層膜を構成し、こ
の誘電対多層膜を２つの光透過性基板の接合面に形成し
て偏光ビームスプリッタとしている。The polarizing beam splitter according to the present invention has a relatively thin film layer H made of a material having a relatively high refractive index in order to obtain the most efficient polarization separation characteristics for the P-polarized light component and the S-polarized light component. And a thin film layer L made of a high-refractive-index material is alternately repeated, and a starting multilayer and a final layer of all the thin-film layers are both composed of a thin-film layer H made of a high-refractive-index material. A film is formed on the joint surface between the two light-transmitting substrates to form a polarizing beam splitter.
【００２４】具体的には、誘電体多層膜は膜構成がＨ／
Ｌ／Ｈ／Ｌ／Ｈである第１の積層と、膜構成がＨ／Ｌ／
Ｈ／Ｌ／Ｈである第２の積層とを含み、第１の積層を構
成する薄膜層Ｈ及び薄膜層Ｌの光学的膜厚の平均値をそ
れぞれ〈Ｈ１〉及び〈Ｌ１〉とし、第２の積層を構成す
る薄膜層Ｈ及び薄膜層Ｌの光学的膜厚の平均値をそれぞ
れ〈Ｈ２〉及び〈Ｌ２〉とし、平均値〈Ｈ１〉と〈Ｌ
１〉の内の小さい方を分母とする平均値〈Ｈ１〉と〈Ｌ
１〉の比をＲ１とし、平均値〈Ｈ２〉と〈Ｌ２〉の内の
小さい方を分母とする平均値〈Ｈ２〉と〈Ｌ２〉の比を
Ｒ２として、これらの比Ｒ１と比Ｒ２の内の小さい方を
Ｑ１、大きい方をＱ２とし、ｍを１〜３までの整数、ｎ
を１〜４までの整数とするときに、次式を満足する偏光
ビームスプリッタとする。Specifically, the dielectric multilayer film has a film configuration of H /
A first stack of L / H / L / H and a film configuration of H / L /
H / L / H, the average of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the first laminate is <H1> and <L1>, respectively. The average values of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the layered structure are <H2> and <L2>, respectively, and the average values <H1> and <L
1><H1> and <L>
1> is R1, and the ratio between the average values <H2> and <L2> is R2, where the smaller of the average values <H2> and <L2> is the denominator, and R2 is the ratio between these ratios R1 and R2. The smaller one is Q1, the larger one is Q2, m is an integer from 1 to 3, n
Is an integer from 1 to 4, the polarization beam splitter satisfies the following expression.
【００２５】 ０. ９５ｍ≦Ｑ１≦１. ２ｍ …(1) ０. ９（ｍ＋ｎ）≦Ｑ２≦１．４（ｍ＋ｎ） …(2) ２≦ｍ＋ｎ≦５ …(3)0.95m ≦ Q1 ≦ 1.2m (1) 0.9 (m + n) ≦ Q2 ≦ 1.4 (m + n) (2) 2 ≦ m + n ≦ 5 (3)
【００２６】また、平均値〈Ｈ１〉と〈Ｌ１〉の内の小
さい方をＭ１とし、平均値〈Ｈ２〉と〈Ｌ２〉の内の小
さい方をＭ２として、これら平均値Ｍ１とＭ２の内の小
さい方を分母としたＭ１とＭ２の比をＲ３とするとき
に、次式を満足することが好ましい。 １．０≦Ｒ３≦１．７ …(4)The smaller of the averages <H1> and <L1> is defined as M1, the smaller of the averages <H2> and <L2> is defined as M2, and the smaller of these averages M1 and M2 is defined as M2. When the ratio between M1 and M2, where the smaller one is the denominator, is R3, it is preferable that the following expression be satisfied. 1.0 ≦ R3 ≦ 1.7 (4)
【００２７】また、第１の積層を構成する薄膜層Ｈの内
の任意の１つの薄膜層の光学的膜厚をＨ１とし、第１の
積層を構成する薄膜層Ｌの内の任意の１つの薄膜層の光
学的膜厚をＬ１とし、第２の積層を構成する薄膜層Ｈの
内の任意の１つの薄膜層の光学的膜厚をＨ２とし、第２
の積層を構成する薄膜層Ｌの内の任意の薄膜層の光学的
膜厚をＬ２としたときに、次式に示す条件を満足するこ
とが好ましい。Further, the optical film thickness of any one of the thin film layers H constituting the first laminate is defined as H1, and any one of the thin film layers L constituting the first laminate is designated as H1. The optical film thickness of the thin film layer is L1, the optical film thickness of any one of the thin film layers H constituting the second lamination is H2,
When the optical film thickness of an arbitrary thin film layer of the thin film layers L constituting the layered structure is L2, it is preferable that the following condition is satisfied.
【００２８】 ０．８０≦Ｈ１／〈Ｈ１〉≦１．１５ …(5) ０．９０≦Ｌ１／〈Ｌ１〉≦１．１０ …(6) ０．７０≦Ｈ２／〈Ｈ２〉≦１．５５ …(7) ０．８５≦Ｌ２／〈Ｌ２〉≦１．１０ …(8)0.80 ≦ H1 / <H1> ≦ 1.15 (5) 0.90 ≦ L1 / <L1> ≦ 1.10 (6) 0.70 ≦ H2 / <H2> ≦ 1.55 ... (7) 0.85≤L2 / <L2> ≤1.10 ... (8)
【００２９】なお、２つの積層を全てＨ／Ｌ／Ｈ／Ｌ／
Ｈの５層としているが、これを６層以上で構成すれば更
に特性を改善することが可能となる。Note that all of the two laminations are H / L / H / L /
Although the five layers of H are used, the characteristics can be further improved if they are composed of six or more layers.
【００３０】第１の実施例の偏光ビームスプリッタは、
条件式(1) の下限値及び条件式(4)の下限値を満足する
実施例であり、次の表１に示すような構成で、誘電体多
層膜２は薄膜層の総数を１７層で形成した膜構成として
いる。The polarization beam splitter of the first embodiment is
This is an embodiment that satisfies the lower limit of Conditional Expression (1) and the lower limit of Conditional Expression (4), and has a configuration as shown in Table 1 below. The formed film configuration is adopted.
【００３１】 表１ 基板／層番号 材質／主成分 屈折率 光学的膜厚ｎd （ｎｍ） 基板３ Ｓ−ＴＩＨ４ ｎg ＝１．７４ − 光透過性接着剤 ｎb ＝１．５６ − 第１７層 ＴｉＯ2 ｎh ＝２．２６ ５０１ 第１６層 ＳｉＯ2 ｎl ＝１．４５ ５６１ 〜第１１層 ＴｉＯ2 ｎh ＝２．２６ １４０ 第１０層 ＳｉＯ2 ｎl ＝１．４５ ２７２ 第９層 ＴｉＯ2 ｎh ＝２．２６ ２１６ 第８層 ＳｉＯ2 ｎl ＝１．４５ ２８１ 〜第３層 ＴｉＯ2 ｎh ＝２．２６ １４１ 第２層 ＳｉＯ2 ｎl ＝１．４５ ２０５ 第１層 ＴｉＯ2 ｎh ＝２．２６ １５３ 基板１ Ｓ−ＴＩＨ４ ｎg ＝１．７４ −Table 1 Substrate / Layer No. Material / Main component Refractive index Optical film thickness nd (nm) Substrate 3 S-TIH4 ng = 1.74 −Light transmitting adhesive NB = 1.56 −17th layer TiO 2 nh = 2.26 501 Sixteenth layer SiO 2 nl = 1.45561 to eleventh layer TiO 2 nh = 2.26 140 Tenth layer SiO 2 nl = 1.45 272 Ninth layer TiO 2 nh = 2.26 216 8th layer SiO 2 nl = 1.45 281 to 3rd layer TiO 2 nh = 2.26 141 second layer SiO 2 nl = 1.45 205 205 1st layer TiO 2 nh = 2.26 153 Substrate 1 S− TIH4 ng = 1.74 −
【００３２】本実施例の誘電体多層膜２は、光透過性基
板１上において、第１層目に光学的膜厚が１５３ｎｍの
薄膜層Ｈを形成し、第２層目に光学的膜厚が２０５ｎｍ
の薄膜層Ｌを形成した後に、第３層目から光学的膜厚が
１４１ｎｍの薄膜層Ｈと光学的膜厚が２８１ｎｍの薄膜
層Ｌの交互層を３回繰り返す。この内の第３層目から第
７層目のＨ／Ｌ／Ｈ／Ｌ／Ｈの薄膜交互層を第１の積層
としている。In the dielectric multilayer film 2 of this embodiment, a thin film layer H having an optical thickness of 153 nm is formed as a first layer on the light transmitting substrate 1, and an optical film thickness is formed as a second layer. Is 205 nm
After the formation of the thin film layer L, the alternate layer of the thin film layer H having an optical thickness of 141 nm and the thin film layer L having an optical thickness of 281 nm is repeated three times from the third layer. Of these, the third to seventh thin film alternating layers of H / L / H / L / H are the first lamination.
【００３３】続いて、第９層目に光学的膜厚が２１６ｎ
ｍの薄膜層Ｈを形成し、第１０層目に光学的膜厚２７２
ｎｍの薄膜層Ｌを形成した後に、第１１層目から光学的
膜厚が１４０ｎｍの薄膜層Ｈと光学的膜厚が５６１ｎｍ
の薄膜層Ｌの交互層を３回繰り返す。この内の第１１層
目から第１５層目までのＨ／Ｌ／Ｈ／Ｌ／Ｈの薄膜交互
層を第２の積層としている。そして、最後の第１７層目
に光学的膜厚が５０１ｎｍの薄膜層Ｈを形成して、総数
１７層の薄膜層で構成する誘電体多層膜２としている。Subsequently, the ninth layer has an optical film thickness of 216n.
m is formed as a thin film layer H, and an optical film thickness 272 is formed as a tenth layer.
After forming the thin film layer L having a thickness of 140 nm, a thin film layer H having an optical thickness of 140 nm and an optical thickness of 561 nm are formed from the eleventh layer.
Is repeated three times. Of these, the thin film alternating layers of H / L / H / L / H from the eleventh layer to the fifteenth layer are used as the second lamination. Then, a thin film layer H having an optical film thickness of 501 nm is formed on the last seventeenth layer to form a dielectric multilayer film 2 composed of a total of 17 thin film layers.
【００３４】これによって、第１の積層を構成する薄膜
層Ｈ及び薄膜層Ｌの光学的膜厚の平均値〈Ｈ１〉及び
〈Ｌ１〉は、それぞれ１４１ｎｍ及び２８１ｎｍとな
る。そして、第２の積層を構成する薄膜層Ｈ及び薄膜層
Ｌの光学的膜厚の平均値〈Ｈ２〉及び〈Ｌ２〉は、それ
ぞれ１４０ｎｍ及び５６１ｎｍとなる。各諸元を次の表
２に示す。As a result, the average values <H1> and <L1> of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the first stack are 141 nm and 281 nm, respectively. Then, the average values <H2> and <L2> of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the second stack are 140 nm and 561 nm, respectively. The specifications are shown in Table 2 below.
【００３５】 表２ 第１の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ１〉＝１４１ｎｍ 第１の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ１〉＝２８１ｎｍ 第２の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ２〉＝１４０ｎｍ 第２の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ２〉＝５６１ｎｍ 条件式(1) Ｒ１＝〈Ｌ１〉／〈Ｈ１〉＝０．９９６ｍ＝Ｑ１ 条件式(2) Ｒ２＝〈Ｌ２〉／〈Ｈ２〉＝１．００（ｍ＋ｎ） ＝Ｑ２ 条件式(3) ｍ＝ｎ＝２、ｍ＋ｎ＝４ 条件式(4) Ｍ１＝〈Ｈ１〉＝１４１、Ｍ２＝〈Ｈ２〉＝１４０ Ｒ３＝Ｍ１／Ｍ２＝１．０１ 条件式(5) 、(6) Ｈ１／〈Ｈ１〉＝Ｌ１／〈Ｌ１〉＝１ 条件式(7) 、(8) Ｈ２／〈Ｈ２〉＝Ｌ２／〈Ｌ２〉＝１Table 2 Average value of the optical film thickness of the thin film layer H of the first laminate <H1> = 141 nm Average value of the optical film thickness of the thin film layer L of the first laminate <L1> = 281 nm Second Average value of the optical film thickness of the laminated thin film layer H <H2> = 140 nm Average value of the optical film thickness of the second laminated thin film layer L <L2> = 561 nm Conditional expression (1) R1 = <L1> / <H1> = 0.996m = Q1 Conditional expression (2) R2 = <L2> / <H2> = 1.00 (m + n) = Q2 Conditional expression (3) m = n = 2, m + n = 4 Conditional expression (4) ) M1 = <H1> = 141, M2 = <H2> = 140 R3 = M1 / M2 = 1.01 Conditional expressions (5) and (6) H1 / <H1> = L1 / <L1> = 1 Conditional expression ( 7), (8) H2 / <H2> = L2 / <L2> = 1
【００３６】このような誘電体多層膜２を有する偏光ビ
ームスプリッタについて、 図１に示すような光入射条件
で透過及び反射したときの、 波長７８０ｎｍにおけるＰ
偏光成分の透過率をＴＰ及びＳ偏光成分の反射率をＲＳ
として、 偏光分離特性の角度依存性を表すグラフを図２
に示す。With respect to the polarization beam splitter having such a dielectric multilayer film 2, when transmitted and reflected under light incident conditions as shown in FIG.
The transmittance of the polarization component is TP and the reflectance of the S polarization component is RS
FIG. 2 is a graph showing the angle dependence of the polarization separation characteristic.
Shown in
【００３７】本実施例の偏光ビームスプリッタは、偏光
分離面に対する光入射角４５°を中心としたときの小傾
角側及び大傾角側の透過光において、Ｐ偏光成分の透過
率ＴＰの非対称性が目立ち始める。従って、条件式(1)
において、「Ｑ１／ｍ」の値は０．９５が下限値とな
る。また、条件式(4) において、「Ｒ３」の値は１．０
が下限値となる。In the polarization beam splitter of this embodiment, the asymmetry of the transmittance TP of the P-polarized component in the transmitted light on the small tilt angle side and the large tilt angle side when the light incident angle with respect to the polarization splitting surface is 45 ° is the center. Start to stand out. Therefore, conditional expression (1)
, The lower limit of the value of “Q1 / m” is 0.95. In conditional expression (4), the value of “R3” is 1.0
Is the lower limit.
【００３８】第２の実施例の偏光ビームスプリッタは、
条件式(1) の上限値及び条件式(4)の上限値を満足する
実施例であり、次の表３に本実施例の誘電体多層膜２の
膜構成を示す。The polarization beam splitter of the second embodiment is
This is an example that satisfies the upper limit of conditional expression (1) and the upper limit of conditional expression (4), and Table 3 below shows the film configuration of the dielectric multilayer film 2 of this example.
【００３９】 表３ 基板／層番号 材質／主成分 屈折率 光学的膜厚ｎd （ｎｍ） 基板３ Ｓ−ＴＩＨ４ ｎg ＝１．７４ − 光透過性接着剤 ｎb ＝１．５６ − 第１７層 ＴｉＯ2 ｎh ＝２．２６ ３２６ 第１６層 ＳｉＯ2 ｎl ＝１．４５ ４５６ 第１５層 ＴｉＯ2 ｎh ＝２．２６ １００ 〜第１０層 ＳｉＯ2 ｎl ＝１．４５ ５０１ 第９層 ＴｉＯ2 ｎh ＝２．２６ ２２１ 第８層 ＳｉＯ2 ｎl ＝１．４５ １６８ 〜第３層 ＴｉＯ2 ｎh ＝２．２６ ２０１ 第２層 ＳｉＯ2 ｎl ＝１．４５ ３１１ 第１層 ＴｉＯ2 ｎh ＝２．２６ ２５２ 基板１ Ｓ−ＴＩＨ４ ｎg ＝１．７４ −Table 3 Substrate / Layer No. Material / Main component Refractive index Optical film thickness nd (nm) Substrate 3 S-TIH4 ng = 1.74 −Light transmitting adhesive NB = 1.56 −17th layer TiO 2 nh = 2.26 326 Sixteenth layer SiO 2 nl = 1.45 456 Fifteenth layer TiO 2 nh = 2.26 100 to tenth layer SiO 2 nl = 1.45 501 Ninth layer TiO 2 nh = 2.26 221 8th layer SiO 2 nl = 1.45 168 to 3rd layer TiO 2 nh = 2.26 201 2nd layer SiO 2 nl = 1.45 311 1st layer TiO 2 nh = 2.26 252 Substrate 1 S− TIH4 ng = 1.74 −
【００４０】本実施例の誘電体多層膜２は、光透過性基
板１上において、第１層目に光学的膜が２５２ｎｍの薄
膜層Ｈを形成し、第２層目に光学的膜厚が３１１ｎｍの
薄膜層Ｌを形成した後に、第３層目から光学的膜厚が２
０１ｎｍの薄膜層Ｈと光学的膜厚が１６８ｎｍの薄膜層
Ｌの交互層を３回繰り返す。この内の第３層目から第７
層目までのＨ／Ｌ／Ｈ／Ｌ／Ｈの薄膜交互層を第１の積
層としている。In the dielectric multilayer film 2 of the present embodiment, a thin film layer H having an optical film of 252 nm is formed as a first layer on the light transmitting substrate 1, and an optical film thickness is formed as a second layer. After the formation of the thin film layer L of 311 nm, the optical film thickness becomes 2 from the third layer.
The alternate layer of the thin film layer H having a thickness of 01 nm and the thin film layer L having an optical thickness of 168 nm is repeated three times. From the third layer to the seventh
The thin film alternating layers of H / L / H / L / H up to the layer are the first lamination.
【００４１】続いて、第９層目に光学的膜厚が２２１ｎ
ｍの薄膜層Ｈを形成した後に、第１０層目から光学的膜
厚が５０１ｎｍの薄膜層Ｌと光学的膜厚が１００ｎｍの
薄膜層Ｈの交互層を３回繰り返す。この内の第１１層目
から第１５層目までのＨ／Ｌ／Ｈ／Ｌ／Ｈの薄膜交互層
を第２の積層としている。その後に、第１６層目に光学
的膜厚が４５６ｎｍの薄膜層Ｌ、そして最後の第１７層
目に光学的膜厚が３２６ｎｍの薄膜層Ｈを形成して、総
数１７層の薄膜層で構成する誘電体多層膜２としてい
る。Subsequently, the optical thickness of the ninth layer is 221n.
After the formation of the m thin film layer H, the alternate layers of the thin film layer L having an optical thickness of 501 nm and the thin film layer H having an optical thickness of 100 nm are repeated three times from the tenth layer. Of these, the thin film alternating layers of H / L / H / L / H from the eleventh layer to the fifteenth layer are used as the second lamination. Thereafter, a thin film layer L having an optical film thickness of 456 nm is formed on the 16th layer, and a thin film layer H having an optical film thickness of 326 nm is formed on the final 17th layer. The dielectric multilayer film 2 is formed.
【００４２】これによって、第１の積層を構成する薄膜
層Ｈ及び薄膜層Ｌの光学的膜厚の平均値〈Ｈ１〉及び
〈Ｌ１〉は、それぞれ２０１ｎｍ及び１６８ｎｍとな
る。そして、第２の積層を構成する薄膜層Ｈ及び薄膜層
Ｌの光学的膜厚の平均値〈Ｈ２〉及び〈Ｌ２〉は、それ
ぞれ１００ｎｍ及び５０１ｎｍとなる。各諸元を次の表
４に示す。As a result, the average values <H1> and <L1> of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the first stack are 201 nm and 168 nm, respectively. The average values <H2> and <L2> of the optical film thicknesses of the thin film layer H and the thin film layer L forming the second stack are 100 nm and 501 nm, respectively. The specifications are shown in Table 4 below.
【００４３】 表４ 第１の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ１〉＝２０１ｎｍ 第１の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ１〉＝１６８ｎｍ 第２の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ２〉＝１００ｎｍ 第２の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ２〉＝５０１ｎｍ 条件式(1) Ｒ１＝〈Ｈ１〉／〈Ｌ１〉＝１．２０ｍ＝Ｑ１ 条件式(2) Ｒ２＝〈Ｌ２〉／〈Ｈ２〉＝１．００（ｍ＋ｎ） ＝Ｑ２ 条件式(3) ｍ＝１、ｎ＝４、ｍ＋ｎ＝５ 条件式(4) Ｍ１＝〈Ｌ１〉＝１６８、Ｍ２＝〈Ｈ２〉＝１００ Ｒ３＝Ｍ１／Ｍ２＝１．６８ 条件式(5) 、(6) Ｈ１／〈Ｈ１〉＝Ｌ１／〈Ｌ１〉＝１ 条件式(7) 、(8) Ｈ２／〈Ｈ２〉＝Ｌ２／〈Ｌ２〉＝１Table 4 Average value of the optical film thickness of the thin film layer H of the first laminate <H1> = 201 nm Average value of the optical film thickness of the thin film layer L of the first laminate <L1> = 168 nm Second Average value of the optical film thickness of the laminated thin film layer H <H2> = 100 nm Average value of the optical film thickness of the second laminated thin film layer L <L2> = 501 nm Conditional expression (1) R1 = <H1> / <L1> = 1.20m = Q1 Conditional expression (2) R2 = <L2> / <H2> = 1.00 (m + n) = Q2 Conditional expression (3) m = 1, n = 4, m + n = 5 Conditional expression (4) M1 = <L1> = 168, M2 = <H2> = 100 R3 = M1 / M2 = 1.68 Conditional expressions (5) and (6) H1 / <H1> = L1 / <L1> = 1 Condition Equations (7) and (8) H2 / <H2> = L2 / <L2> = 1
【００４４】このような誘電体多層膜２を有する偏光ビ
ームスプリッタについて、図１に示すような光入射条件
で光透過及び光反射したときの、波長７８０ｎｍにおけ
るＰ偏光成分の透過率をＴＰ及びＳ偏光成分の反射率を
ＲＳとして、偏光分離特性の角度依存性を表すグラフを
図３に示す。With respect to the polarizing beam splitter having such a dielectric multilayer film 2, the transmittance of the P-polarized light component at a wavelength of 780 nm when transmitted and reflected under the light incident conditions as shown in FIG. FIG. 3 is a graph showing the angle dependence of the polarization separation characteristics, where the reflectance of the polarization component is RS.
【００４５】本実施例による偏光ビームスプリッタは、
偏光分離面に対する光入射角４５°を中心としたときの
小傾角側及び大傾角側の透過光において、局所的にＰ偏
光成分の透過率ＴＰの非対称性が目立ち始める。従っ
て、条件式(1) において、「Ｑ１／ｍ」の値は１．２が
上限値となる。また、条件式(4) において、「Ｒ３」の
値は１．７が上限値となる。The polarizing beam splitter according to the present embodiment is
The asymmetry of the transmittance TP of the P-polarized light component starts to be conspicuous locally in the transmitted light on the small tilt angle side and the large tilt angle side when the light incident angle with respect to the polarization separation surface is 45 °. Therefore, in the conditional expression (1), the upper limit of the value of “Q1 / m” is 1.2. In conditional expression (4), the upper limit of the value of “R3” is 1.7.
【００４６】第３の実施例の偏光ビームスプリッタは、
条件式(2) の上限値及び下限値を満足する実施例であ
る。次の表５に本実施例の誘電体多層膜２の膜構成を示
す。The polarization beam splitter of the third embodiment is
This is an example that satisfies the upper limit and the lower limit of conditional expression (2). Table 5 below shows the film configuration of the dielectric multilayer film 2 of this example.
【００４７】 表５ 基板／層番号 材質／主成分 屈折率 光学的膜厚ｎd （ｎｍ） 基板３ Ｓ−ＴＩＨ４ ｎg ＝１．７４ − 光透過性接着剤 ｎb ＝１．５６ − 第１７層 ＴｉＯ2 ｎh ＝２．２６ ２８２ 第１６層 ＳｉＯ2 ｎl ＝１．４５ ４４２ 〜第１１層 ＴｉＯ2 ｎh ＝２．２６ １６２ 第１０層 ＳｉＯ2 ｎl ＝１．４５ １５３ 第９層 ＴｉＯ2 ｎh ＝２．２６ ４４４ 第８層 ＳｉＯ2 ｎl ＝１．４５ １８２ 〜第３層 ＴｉＯ2 ｎh ＝２．２６ １８２ 第２層 ＳｉＯ2 ｎl ＝１．４５ １７８ 第１層 ＴｉＯ2 ｎh ＝２．２６ ４０８ 基板１ Ｓ−ＴＩＨ４ ｎg ＝１．７４ −Table 5 Substrate / Layer Number Material / Main Component Refractive Index Optical Film Thickness nd (nm) Substrate 3 S-TIH4 ng = 1.74 −Light-Transmissive Adhesive nb = 1.56 −17th Layer TiO 2 nh = 2.26 282 Sixteenth layer SiO 2 nl = 1.45 442 to eleventh layer TiO 2 nh = 2.26 162 Tenth layer SiO 2 nl = 1.45 153 Ninth layer TiO 2 nh = 2.26 444 8th layer SiO 2 nl = 1.45 182 to 3rd layer TiO 2 nh = 2.26 182 2nd layer SiO 2 nl = 1.45 178 1st layer TiO 2 nh = 2.26 408 Substrate 1 S− TIH4 ng = 1.74 −
【００４８】本実施例の誘電体多層膜２は、光透過性基
板１上において第１層目に光学的膜厚が４０８ｎｍの薄
膜層Ｈを形成し、第２層面に光学的膜厚が１７８ｎｍの
薄膜層Ｌを形成した後に、第３層目から光学的膜厚が共
に１８２ｎｍの薄膜層Ｈと薄膜層Ｌの交互層を３回繰り
返しす。この内の第３層目から第７層目までのＨ／Ｌ／
Ｈ／Ｌ／Ｈの薄膜交互層を第１の積層としている。In the dielectric multilayer film 2 of the present embodiment, a thin film layer H having an optical thickness of 408 nm is formed as a first layer on the light transmitting substrate 1 and an optical thickness of 178 nm is formed on the second layer surface. After the formation of the thin film layer L, the alternate layers of the thin film layer H and the thin film layer L each having an optical thickness of 182 nm are repeated three times from the third layer. Of these, the H / L /
The thin film alternating layers of H / L / H are the first lamination.
【００４９】続いて、第９層目に光学的膜厚が４４４ｎ
ｍの薄膜層Ｈを形成し、第１０層目に光学的膜厚が１５
３ｎｍの薄膜層Ｌを形成した後に、第１１層目から光学
的膜厚が１６２ｎｍの薄膜層Ｈと光学的膜厚が４４２ｎ
ｍの薄膜層Ｌの交互層を３回繰り返す。この内の第１１
層目から第１５層目までのＨ／Ｌ／Ｈ／Ｌ／Ｈの薄膜交
互層を第２の積層としている。そして、最後の第１７層
目に光学的膜厚が２８２ｎｍの薄膜層Ｈを形成して、総
数１７層の薄膜層で構成する誘電体多層膜２としてい
る。Subsequently, the ninth layer has an optical film thickness of 444n.
m of the thin film layer H, and the tenth layer has an optical thickness of 15
After forming the thin film layer L of 3 nm, the thin film layer H having an optical film thickness of 162 nm and the optical film thickness of 442 n
The alternating layers of m thin film layers L are repeated three times. Eleventh of these
The thin film alternating layers of H / L / H / L / H from the first layer to the fifteenth layer are used as the second lamination. Then, a thin film layer H having an optical film thickness of 282 nm is formed on the last seventeenth layer to form a dielectric multilayer film 2 composed of a total of 17 thin film layers.
【００５０】これによって、第１の積層を構成する薄膜
層Ｈ及び薄膜層Ｌの光学的膜厚の平均値〈Ｈ１〉及び
〈Ｌ１〉は共に１８２ｎｍとなる。そして、第２の積層
を構成する薄膜層Ｈ及び薄膜層Ｌの光学的膜厚の平均値
〈Ｈ２〉及び〈Ｌ２〉は、それぞれ１６２ｎｍ及び４４
２ｎｍとなる。各諸元を次の表６に示す。As a result, the average values <H1> and <L1> of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the first laminate are both 182 nm. The average values <H2> and <L2> of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the second stack are 162 nm and 44 nm, respectively.
2 nm. The specifications are shown in Table 6 below.
【００５１】 表６ 第１の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ１〉＝１８２ｎｍ 第１の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ１〉＝１８２ｎｍ 第２の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ２〉＝１６２ｎｍ 第２の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ２〉＝４４２ｎｍ 条件式(1) Ｒ１＝〈Ｈ１〉／〈Ｌ１〉＝１．００ｍ＝Ｑ１ 条件式(2) Ｒ２＝〈Ｌ２〉／〈Ｈ２〉＝０．９１（ｍ＋ｎ） ＝Ｑ２ 又はＲ２＝１．３６（ｍ＋ｎ）＝Ｑ２ 条件式(3) ｍ＝１、ｎ＝１、ｍ＋ｎ＝２ 又はｍ＝１、ｎ＝２、ｍ＋ｎ＝５ 条件式(4) Ｍ１＝〈Ｈ１〉＝〈Ｌ１〉＝１８２ Ｍ２＝〈Ｈ２〉＝１６２ Ｒ３＝Ｍ１／Ｍ２＝１．１２ 条件式(5) 、(6) Ｈ１／〈Ｈ１〉＝Ｌ１／〈Ｌ１〉＝１ 条件式(7) 、(8) Ｈ２／〈Ｈ２〉＝Ｌ２／〈Ｌ２〉＝１Table 6 Average value of optical film thickness of thin film layer H of first laminate <H1> = 182 nm Average value of optical film thickness of thin film layer L of first laminate <L1> = 182 nm Second Average value of the optical film thickness of the laminated thin film layer H <H2> = 162 nm Average value of the optical film thickness of the second laminated thin film layer L <L2> = 442 nm Conditional expression (1) R1 = <H1> / <L1> = 1.00m = Q1 Conditional expression (2) R2 = <L2> / <H2> = 0.91 (m + n) = Q2 or R2 = 1.36 (m + n) = Q2 Conditional expression (3) m = 1, n = 1, m + n = 2 or m = 1, n = 2, m + n = 5 Conditional expression (4) M1 = <H1> = <L1> = 182 M2 = <H2> = 162 R3 = M1 / M2 = 1.12 Conditional Expressions (5) and (6) H1 / <H1> = L1 / <L1> = 1 Conditional Expressions (7) and (8) H2 / <H2> = L2 / <L2> = 1
【００５２】このような誘電体多層膜２を有する偏光ビ
ームスプリッタについて、 図１に示すような光入射条件
で光透過及び光反射したときの波長７８０ｎｍにおける
Ｐ偏光成分の透過率をＴＰ及びＳ偏光成分の反射率をＲ
Ｓとして、 偏光分離特性の角度依存性を表すグラフを図
４に示す。With respect to the polarizing beam splitter having such a dielectric multilayer film 2, the transmittance of the P-polarized light component at a wavelength of 780 nm when transmitted and reflected under the light incident conditions as shown in FIG. The reflectance of the component is R
FIG. 4 is a graph showing the angle dependency of the polarization separation characteristic as S.
【００５３】本実施例による偏光ビームスプリッタは、
偏光分離面に対する光入射角４５°を中心としたときの
小傾角側及び大傾角側の透過光において、Ｐ偏光成分の
透過率ＴＰは比較的に対称性は良好である。The polarization beam splitter according to this embodiment is
The transmittance TP of the P-polarized light component has relatively good symmetry in the transmitted light on the small tilt angle side and the large tilt angle side when the light incident angle with respect to the polarization separation surface is 45 °.
【００５４】しかし、第２の積層を構成する薄膜層Ｈと
薄膜層Ｌの光学的膜厚の比を見ると、整数比からのずれ
が大きくなり、薄膜蒸着における膜厚制御が難しくなる
ので、実際に蒸着される膜厚の設計値に対する誤差が現
われ易い。これによって、Ｐ偏光成分の透過率ＴＰの対
称性が崩れ易くなる。従って、条件式(2) において、
「Ｑ２／（ｍ＋ｎ）」の値は０．９が下限値で１．４が
上限値となる。However, looking at the ratio of the optical film thicknesses of the thin film layer H and the thin film layer L constituting the second stack, the deviation from the integer ratio becomes large, and it becomes difficult to control the film thickness in the thin film deposition. An error with respect to the design value of the film thickness actually deposited tends to appear. Thereby, the symmetry of the transmittance TP of the P-polarized component is easily broken. Therefore, in conditional expression (2),
As for the value of “Q2 / (m + n)”, 0.9 is the lower limit and 1.4 is the upper limit.
【００５５】第４の実施例の偏光ビームスプリッタは、
条件式(3) の上限値を満足する実施例である。次の表７
に本実施例の誘電体多層膜２の膜構成を示す。The polarization beam splitter of the fourth embodiment is
This is an embodiment that satisfies the upper limit value of conditional expression (3). Table 7 below
The film configuration of the dielectric multilayer film 2 of the present embodiment is shown in FIG.
【００５６】 表７ 第４の実施例 基板／層番号 材質／主成分 屈折率 光学的膜厚ｎd （ｎｍ） 基板３ Ｓ−ＴＩＨ４ ｎg ＝１．７４ − 光透過性接着剤 ｎb ＝１．５６ − 第１７層 ＴｉＯ2 ｎh ＝２．２６ ６１７ 第１６層 ＳｉＯ2 ｎl ＝１．４５ ２８５ 〜第１１層 ＴｉＯ2 ｎh ＝２．２６ １４２ 第１０層 ＳｉＯ2 ｎl ＝１．４５ ３００ 第９層 ＴｉＯ2 ｎh ＝２．２６ １２１ 第８層 ＳｉＯ2 ｎl ＝１．４５ ５４８ 〜第３層 ＴｉＯ2 ｎh ＝２．２６ １０８ 第２層 ＳｉＯ2 ｎl ＝１．４５ ３０１ 第１層 ＴｉＯ2 ｎh ＝２．２６ ２６６ 基板 Ｓ−ＴＩＨ４ ｎg ＝１．７４ −Table 7 Fourth Embodiment Substrate / Layer Number Material / Main Component Refractive Index Optical Film Thickness nd (nm) Substrate 3 S-TIH4 ng = 1.74 − Light-Transmissive Adhesive nb = 1.56 − Seventeenth layer TiO 2 nh = 2.26 617 Sixteenth layer SiO 2 nl = 1.45285 to eleventh layer TiO 2 nh = 2.26 142 Tenth layer SiO 2 nl = 1.45 300 Ninth layer TiO 2 nh = 2.26 121 Eighth layer SiO 2 nl = 1.45 548 to third layer TiO 2 nh = 2.26 108 Second layer SiO 2 nl = 1.45 301 First layer TiO 2 nh = 2.26 266 substrate S-TIH4 ng = 1.74 −
【００５７】本実施例の誘電体多層膜２は、光透過性基
板１上において、第１層目に光学的膜厚が２６６ｎｍの
薄膜層Ｈを形成し、第２層目に光学的膜厚が３０１ｎｍ
の薄膜層Ｌを形成した後に、第３層目から光学的膜厚が
１０８ｎｍの薄膜層Ｈと光学的膜厚が５４８ｎｍの薄膜
層Ｌの交互層を３回繰り返す。この内の第３層目から第
７層目までのＨ／Ｌ／Ｈ／Ｌ／Ｈの薄膜交互層を第１の
積層としている。In the dielectric multilayer film 2 of the present embodiment, a thin film layer H having an optical thickness of 266 nm is formed as a first layer on the light transmitting substrate 1, and an optical film thickness is formed as a second layer. Is 301 nm
After the formation of the thin film layer L, the alternate layer of the thin film layer H having an optical thickness of 108 nm and the thin film layer L having an optical thickness of 548 nm is repeated three times from the third layer. Of these, the thin film alternating layers of H / L / H / L / H from the third layer to the seventh layer are the first lamination.
【００５８】続いて、第９層目に光学的膜厚が１２１ｎ
ｍの薄膜層Ｈを形成し、第１０層目に光学的膜厚が３０
０ｎｍの薄膜層Ｌを形成した後に、第１１層目から光学
的膜厚が１４２ｎｍの薄膜層Ｈと光学的膜厚が２８５ｎ
ｍの薄膜層Ｌの交互層を３回繰り返す。この内の第１１
層目から第１５層目までのＨ／Ｌ／Ｈ／Ｌ／Ｈの交互層
を第２の積層としている。そして、最後の第１７層目に
光学的膜厚が６１７ｎｍの薄膜層Ｈを形成して、総数１
７層の薄膜層で構成する誘電体多層膜２としている。Subsequently, the optical thickness of the ninth layer is 121 n.
m of the thin film layer H, and the tenth layer has an optical film thickness of 30.
After forming the thin film layer L having a thickness of 0 nm, the thin film layer H having an optical thickness of 142 nm and an optical thickness of 285 n
The alternate layers of m thin film layers L are repeated three times. Eleventh of these
Alternate layers of H / L / H / L / H from the first layer to the fifteenth layer are used as the second laminate. Then, a thin film layer H having an optical thickness of 617 nm is formed on the last seventeenth layer, and
The dielectric multilayer film 2 is composed of seven thin film layers.
【００５９】これによって、第１の積層を構成する薄膜
層Ｈ及び薄膜層Ｌの光学的膜厚の平均値〈Ｈ１〉及び
〈Ｌ１〉は、それぞれ１０８ｎｍ及び５４８ｎｍとな
る。更に、第２の積層を構成する薄膜層Ｈ及び薄膜層Ｌ
の光学的膜厚の平均値〈Ｈ２〉及び〈Ｌ２〉は、それぞ
れ１４２ｎｍ及び２８５ｎｍとなる。各諸元を次の表８
に示す。As a result, the average values <H1> and <L1> of the optical film thickness of the thin film layer H and the thin film layer L constituting the first laminate are 108 nm and 548 nm, respectively. Further, the thin film layer H and the thin film layer L constituting the second lamination
The average values <H2> and <L2> of the optical film thicknesses are 142 nm and 285 nm, respectively. Table 8 shows the specifications.
Shown in
【００６０】 表８ 第１の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ１〉＝１０８ｎｍ 第１の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ１〉＝５４８ｎｍ 第２の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ２〉＝１４２ｎｍ 第２の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ２〉＝２８５ｎｍ 条件式(1) Ｒ１＝〈Ｌ１〉／〈Ｈ１〉＝１．０１（ｍ＋ｎ） 条件式(2) ＝Ｑ２、Ｒ２＝〈Ｌ２〉／〈Ｈ２〉＝１．００＝Ｑ１ 条件式(3) ｍ＝２、ｎ＝３、ｍ＋ｎ＝５ 条件式(4) Ｍ１＝〈Ｈ１〉＝１０８、Ｍ２＝〈Ｈ２〉＝１４２ Ｒ３＝Ｍ２／Ｍ１＝１．３１ 条件式(5) 、(6) Ｈ１／〈Ｈ１〉＝Ｌ１／〈Ｌ１〉＝１ 条件式(7) 、(8) Ｈ２／〈Ｈ２〉＝Ｌ２／〈Ｌ２〉＝１Table 8 Average value of optical film thickness of thin film layer H of first laminate <H1> = 108 nm Average value of optical film thickness of thin film layer L of first laminate <L1> = 548 nm Second Average value of optical film thickness of laminated thin film layer H <H2> = 142 nm Average value of optical film thickness of second laminated thin film layer L <L2> = 285 nm Conditional expression (1) R1 = <L1> / <H1> = 1.01 (m + n) Conditional expression (2) = Q2, R2 = <L2> / <H2> = 1.00 = Q1 Conditional expression (3) m = 2, n = 3, m + n = 5 Equation (4) M1 = <H1> = 108, M2 = <H2> = 142 R3 = M2 / M1 = 1.31 Conditional Equations (5) and (6) H1 / <H1> = L1 / <L1> = 1 Conditional expressions (7), (8) H2 / <H2> = L2 / <L2> = 1
【００６１】以上のような誘電体多層膜２を有する偏光
ビームスプリッタについて、 図１に示すような光入射条
件で光透過及び光反射したときの波長７８０ｎｍにおけ
るＰ偏光成分の透過率をＴＰ及びＳ偏光成分の反射率を
ＲＳとして、 偏光分離特性の角度依存性を表すグラフを
図５に示す。With respect to the polarizing beam splitter having the dielectric multilayer film 2 as described above, the transmittance of the P-polarized light component at a wavelength of 780 nm when the light is transmitted and reflected under the light incident conditions as shown in FIG. FIG. 5 is a graph showing the angle dependence of the polarization separation characteristic, where the reflectance of the polarization component is RS.
【００６２】本実施例による偏光ビームスプリッタは、
偏光分離面に対する光入射角４５°を中心にしたときの
小傾角側及び大傾角側の透過率において、Ｐ偏光成分の
透過率ＴＰの非対称性が目立ち始める。従って、条件式
(3) において、「ｍ＋ｎ」の値は５が上限値となる。The polarizing beam splitter according to the present embodiment
Asymmetry of the transmittance TP of the P-polarized component starts to be noticeable in the transmittance on the small tilt angle side and the large tilt angle side when the light incident angle with respect to the polarization separation surface is 45 °. Therefore, the conditional expression
In (3), the upper limit of the value of “m + n” is 5.
【００６３】第５の実施例の偏光ビームスプリッタは、
条件式(3) の下限値及び条件式(7)の上限値を満足する
実施例である。次の表９に本実施例の誘電体多層膜２の
膜構成を示す。The polarization beam splitter of the fifth embodiment is
This is an example that satisfies the lower limit of conditional expression (3) and the upper limit of conditional expression (7). Table 9 below shows the film configuration of the dielectric multilayer film 2 of this example.
【００６４】 表９ 基板／層番号 材質／主成分 屈折率 光学的膜厚ｎd （ｎｍ） 基板３ Ｓ−ＴＩＨ４ ｎg ＝１．７４ − 光透過性接着剤 ｎb ＝１．５６ − 第１７層 ＴｉＯ2 ｎh ＝２．２６ ３２１ 第１６層 ＳｉＯ2 ｎl ＝１．４５ ４０７ 第１５層 ＴｉＯ2 ｎh ＝２．２６ １５２ 第１４層 ＳｉＯ2 ｎl ＝１．４５ ４７７ 第１３層 ＴｉＯ2 ｎh ＝２．２６ １４９ 第１２層 ＳｉＯ2 ｎl ＝１．４５ ４４６ 第１１層 ＴｉＯ2 ｎh ＝２．２６ ２０３ 第１０層 ＳｉＯ2 ｎl ＝１．４５ ２４１ 第９層 ＴｉＯ2 ｎh ＝２．２６ １９８ 第８層 ＳｉＯ2 ｎl ＝１．４５ ２１１ 第７層 ＴｉＯ2 ｎh ＝２．２６ １７９ 第６層 ＴｉＯ2 ｎh ＝２．２６ ２０１ 第５層 ＳｉＯ2 ｎl ＝１．４５ １８３ 第４層 ＳｉＯ2 ｎl ＝１．４５ ２８２ 第３層 ＴｉＯ2 ｎh ＝２．２６ １７５ 第２層 ＴｉＯ2 ｎh ＝２．２６ １７３ 第１層 ＳｉＯ2 ｎl ＝１．４５ １００ 基板１ Ｓ−ＴＩＨ４ ｎg ＝１．７４ −Table 9 Substrate / Layer Number Material / Main Component Refractive Index Optical Film Thickness nd (nm) Substrate 3 S-TIH4 ng = 1.74 −Light-Transmissive Adhesive nb = 1.56 −17th Layer TiO 2 nh = 2.26 321 Sixteenth layer SiO 2 nl = 1.45 407 Fifteenth layer TiO 2 nh = 2.26 152 Fourteenth layer SiO 2 nl = 1.45 477 thirteenth layer TiO 2 nh = 2.26 149 12th layer SiO 2 nl = 1.45 446 11th layer TiO 2 nh = 2.26 203 10th layer SiO 2 nl = 1.45 241 ninth layer TiO 2 nh = 2.26 198 eighth layer SiO 2 nl = 1.445 211 7th layer TiO 2 nh = 2.26 179 6th layer TiO 2 nh = 2.26 201 5th layer SiO 2 nl = 1.45 183 4th layer SiO 2 nl = 1.45 282 3 layer TiO 2 nh = 2.26 175 Second layer TiO 2 nh = 2.26 173 First layer SiO 2 nl = 1.45 100 Substrate 1 S-TIH4 ng = 1.74 −
【００６５】本実施例の誘電体多層膜２は、光透過性基
板１上において、第１層目に光学的膜厚が１００ｎｍの
薄膜層Ｈを形成し、第２層目に光学的膜厚が１７３ｎｍ
の薄膜層Ｌ、第３層目に光学的膜厚が１７５ｎｍの薄膜
層Ｈを形成し、第４層目に光学的膜厚が２８２ｎｍの薄
膜層Ｌを形成する。その後に、第５層目から第９層目ま
でに、光学的膜厚の平均値が１８７ｎｍの薄膜層Ｈと、
光学的膜厚の平均値が２０６ｎｍの薄膜層Ｌが、Ｈ／Ｌ
／Ｈ／Ｌ／Ｈの薄膜交互層で構成する第１の積層を形成
する。In the dielectric multilayer film 2 of the present embodiment, a thin film layer H having an optical thickness of 100 nm is formed as a first layer on the light transmitting substrate 1 and an optical film thickness is formed as a second layer. Is 173 nm
A thin film layer H having an optical film thickness of 175 nm is formed on the third layer, and a thin film layer L having an optical film thickness of 282 nm is formed on the fourth layer. Thereafter, from the fifth layer to the ninth layer, a thin film layer H having an average optical thickness of 187 nm,
The thin film layer L having an average optical film thickness of 206 nm is H / L
A first stack composed of / H / L / H thin film alternating layers is formed.
【００６６】続いて、第１０層目に光学的膜厚が２４１
ｎｍの薄膜層Ｌを形成し、第１１層目に光学的膜厚が２
０３ｎｍの薄膜層Ｈを形成し、第１２層目に光学的膜厚
が４４６ｎｍの薄膜層Ｌを形成している。そして、第１
３層目から第１７層目までに、光学的膜厚の平均値が２
０７ｎｍの薄膜層Ｈと、光学的膜厚の平均値が４４２ｎ
ｍの薄膜層Ｌが、Ｈ／Ｌ／Ｈ／Ｌ／Ｈの薄膜交互層で構
成する第２の積層を形成して、総数１７層の薄膜層で構
成する誘電体多層膜２としている。各諸元を次の表１０
に示す。Subsequently, an optical film thickness of 241
A thin film layer L having a thickness of 2 nm is formed on the eleventh layer.
A thin film layer H having a thickness of 03 nm is formed, and a thin film layer L having an optical thickness of 446 nm is formed as a twelfth layer. And the first
From the third layer to the seventeenth layer, the average value of the optical film thickness is 2
The average value of the thin film layer H of 07 nm and the optical film thickness is 442n.
A second multilayer composed of m thin film layers L composed of H / L / H / L / H thin film alternating layers is formed to form a dielectric multilayer film 2 composed of a total of 17 thin film layers. Table 10 shows the specifications.
Shown in
【００６７】 表１０ 第１の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ１〉＝１８７ｎｍ 第１の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ１〉＝２０６ｎｍ 第２の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ２〉＝２０７ｎｍ 第２の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ２〉＝４４２ｎｍ 条件式(1) Ｒ１＝〈Ｌ１〉／〈Ｈ１〉＝１．１０＝Ｑ１ 条件式(2) Ｒ２＝〈Ｌ２〉／〈Ｈ２〉＝１．０７（ｍ＋ｎ） ＝Ｑ２ 条件式(3) ｍ＝ｎ＝１、ｍ＋ｎ＝２ 条件式(4) Ｍ１＝〈Ｈ１〉＝１８７、Ｍ２＝〈Ｈ２〉＝２０７ Ｒ３＝Ｍ２／Ｍ１＝１．１１ 条件式(5) ０．９６≦Ｈ１／〈Ｈ１〉≦１．０６ 条件式(6) ０．９８≦Ｌ１／〈Ｌ１〉≦１．０２ 条件式(7) ０．７２≦Ｈ２／〈Ｈ２〉≦１．５５ 条件式(8) ０．９２≦Ｌ２／〈Ｌ２〉≦１．０８Table 10 Average value of the optical film thickness of the thin film layer H of the first laminate <H1> = 187 nm Average value of the optical film thickness of the thin film layer L of the first laminate <L1> = 206 nm Second Average value of optical film thickness of laminated thin film layer H <H2> = 207 nm Average value of optical film thickness of second laminated thin film layer L <L2> = 442 nm Conditional expression (1) R1 = <L1> / <H1> = 1.10 = Q1 Conditional expression (2) R2 = <L2> / <H2> = 1.07 (m + n) = Q2 Conditional expression (3) m = n = 1, m + n = 2 Conditional expression (4 M1 = <H1> = 187, M2 = <H2> = 207 R3 = M2 / M1 = 1.11 Conditional expression (5) 0.96 ≦ H1 / <H1> ≦ 1.06 Conditional expression (6) 98 ≦ L1 / <L1> ≦ 1.02 Conditional expression (7) 0.72 ≦ H2 / <H2> ≦ 1.55 Conditional expression (8) 0.92 ≦ L2 / <L2> ≦ 1.08
【００６８】このような誘電体多層膜２を有する偏光ビ
ームスプリッタについて、図１に示すような光入射条件
で光透過及び光反射したときの波長７８０ｎｍにおける
Ｐ偏光成分の透過率ＴＰ及びＳ偏光成分の反射率ＲＳを
表す偏光分離特性の角度依存件を表すグラフを図６に示
す。With respect to the polarization beam splitter having such a dielectric multilayer film 2, the transmittance TP and the S polarization component of the P-polarized component at a wavelength of 780 nm when the light is transmitted and reflected under the light incident conditions as shown in FIG. FIG. 6 is a graph showing the angle dependence of the polarization separation characteristic indicating the reflectance RS.
【００６９】本実施例による偏光ビームスプリッタは、
偏光分離面に対する光入射角４５°を中心としたときの
小傾角側及び大傾角側の透過光において、Ｐ偏光成分の
透過率ＴＰの対称性は良好である。The polarization beam splitter according to this embodiment is
The symmetry of the transmittance TP of the P-polarized component is good in the transmitted light on the small tilt angle side and the large tilt angle side when the light incident angle with respect to the polarization separation surface is 45 °.
【００７０】しかし、第２の積層を構成する薄膜層Ｈの
光学的膜厚の平均値〈Ｈ２〉に対するそれぞれの薄膜層
Ｈの光学的膜厚Ｈ２との膜厚差が大きくなる。これによ
って、薄膜蒸着における膜厚制御が難しくなるために、
実際に蒸着される膜厚の設計値に対する誤差が出易くな
り、Ｐ偏光成分の透過率ＴＰの対称性も崩れ易くなる。
従って、条件式(7) において、「Ｈ２／〈Ｈ２〉」の値
は１．５５が上限値となり、また「ｍ＋ｎ」の値は２と
なって、条件式(3) の下限値となる。However, the film thickness difference between the optical film thickness H2 of each thin film layer H and the average value <H2> of the optical film thicknesses of the thin film layers H constituting the second stack increases. This makes it difficult to control the film thickness in thin film deposition.
An error with respect to the design value of the actually deposited film thickness is likely to occur, and the symmetry of the transmittance TP of the P-polarized light component is likely to be lost.
Accordingly, in the conditional expression (7), the value of “H2 / <H2>” is 1.55 as the upper limit, and the value of “m + n” is 2 as the lower limit of conditional expression (3).
【００７１】第６の実施例の偏光ビームスプリッタは、
条件式(5) 、(6) 、(8) の上限値及び下限値、そして条
件式(7) の下限値を満足する実施例である。次の表１１
に本実施例の誘電体多層膜２の膜構成を示す。The polarization beam splitter of the sixth embodiment is
This embodiment satisfies the upper and lower limits of conditional expressions (5), (6) and (8) and the lower limit of conditional expression (7). Table 11 below
The film configuration of the dielectric multilayer film 2 of the present embodiment is shown in FIG.
【００７２】 表１１ 基板／層番号 材質／主成分 屈折率 光学的膜厚ｎd （ｎｍ） 基板３ Ｓ−ＴＩＨ４ ｎg ＝１．７４ − 光透過性接着剤 ｎh ＝１．５６ − 第１３層 ＴｉＯ2 ｎh ＝２．２６ ２８５ 第１２層 ＳｉＯ2 ｎl ＝１．４５ ４０７ 第１１層 ＴｉＯ2 ｎh ＝２．２６ １４６ 第１０層 ＳｉＯ2 ｎl ＝１．４５ ５０２ 第９層 ＴｉＯ2 ｎh ＝２．２６ １８８ 第８層 ＳｉＯ2 ｎl ＝１．４５ ３２５ 第７層 ＴｉＯ2 ｎh ＝２．２６ １９４ 第６層 ＳｉＯ2 ｎl ＝１．４５ ２４０ 第５層 ＴｉＯ2 ｎh ＝２．２６ ２０８ 第４層 ＳｉＯ2 ｎl ＝１．４５ ２００ 第３層 ＴｉＯ2 ｎh ＝２．２６ １４７ 第２層 ＳｉＯ2 ｎl ＝１．４５ １８０ 第１層 ＴｉＯ2 ｎh ＝２．２６ ２６５ 基板１ Ｓ−ＴＩＨ４ ｎg ＝１．７４ − Table 11 Substrate / Layer Number Material / Main Component Refractive Index Optical Film Thickness nd (nm) Substrate 3 S-TIH4 ng = 1.74−Light-Transmissive Adhesive nh = 1.56−Thirteenth Layer TiO 2 nh = 2.26 285 12th layer SiO 2 nl = 1.45 407 11th layer TiO 2 nh = 2.26 146 10th layer SiO 2 nl = 1.45 502 9th layer TiO 2 nh = 2.26 188 Eighth layer SiO 2 nl = 1.45 325 Seventh layer TiO 2 nh = 2.26 194 Sixth layer SiO 2 nl = 1.45 240 Fifth layer TiO 2 nh = 2.26 208 Fourth layer SiO 2 nl = 1.45 200 Third layer TiO 2 nh = 2.26 147 Second layer SiO 2 nl = 1.45 180 First layer TiO 2 nh = 2.26 265 Substrate 1 S-TIH4 ng = 1.74 −
【００７３】本実施例の誘電体多層膜２は、光透過性基
板１上において、第１層目に光学的膜厚が２６５ｎｍの
薄膜層Ｈ、第２層目に光学的膜厚が１８０ｎｍの薄膜層
Ｌを形成した後に、第３層目から第７層目までに、光学
的膜厚の平均値が１８３ｎｍの薄膜層Ｈと光学的膜厚の
平均値が２２０ｎｍの薄膜層Ｌが、Ｈ／Ｌ／Ｈ／Ｌ／Ｈ
の薄膜交互層により構成されて第１の積層を形成してい
る。The dielectric multilayer film 2 according to the present embodiment has a first layer of a thin film layer H having an optical thickness of 265 nm and a second layer having a thickness of 180 nm on the light transmitting substrate 1. After the formation of the thin film layer L, a thin film layer H having an average optical film thickness of 183 nm and a thin film layer L having an average optical film thickness of 220 nm are formed from the third layer to the seventh layer. / L / H / L / H
To form a first laminate.
【００７４】続いて、第８層目に光学的膜厚が３２５ｎ
ｍの薄膜層Ｌを形成した後に、第９層目から第１３層目
までに、光学的膜厚の平均値が２０６ｎｍの薄膜層Ｈと
光学的膜厚の平均値が４５５ｎｍの薄膜層Ｌが、Ｈ／Ｌ
／Ｈ／Ｌ／Ｈの薄膜交互層により構成されて第２の積層
を形成して、総数１７層の薄膜層で構成する誘電体多層
膜２としている。各諸元を次の表１２に示す。Subsequently, the optical thickness of the eighth layer is 325 n.
After forming the thin film layer L having a thickness of m, the thin film layer H having an average optical thickness of 206 nm and the thin film layer L having an average optical thickness of 455 nm are formed in the ninth to thirteenth layers. , H / L
/ H / L / H thin film alternating layers to form a second stack, thereby forming a dielectric multilayer film 2 consisting of a total of 17 thin film layers. Table 12 shows each data.
【００７５】 表１２ 第１の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ１〉＝１８３ｎｍ 第１の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ１〉＝２２０ｎｍ 第２の積層の薄膜層Ｈの光学的膜厚の平均値 〈Ｈ２〉＝２０６ｎｍ 第２の積層の薄膜層Ｌの光学的膜厚の平均値 〈Ｌ２〉＝４５５ｎｍ 条件式(1) Ｒ１＝〈Ｌ１〉／〈Ｈ１〉＝１．２０ｍ＝Ｑ１ 条件式(2) Ｒ２＝〈Ｌ２〉／〈Ｈ２〉＝１．１１（ｍ＋ｎ） ＝Ｑ２ 条件式(3) ｍ＝１、ｎ＝１、ｍ＋ｎ＝２ 条件式(4) Ｍ１＝〈Ｈ１〉＝１８３、Ｍ２＝〈Ｈ２〉＝２０６ Ｒ３＝Ｍ２／Ｍ１＝１．１３ 条件式(5) ０．８０≦Ｈ１／〈Ｈ１〉≦１．１４ 条件式(6) ０．９１≦Ｌ１／〈Ｌ１〉≦１．０９ 条件式(7) ０．７１≦Ｈ２／〈Ｈ２〉≦１．３８ 条件式(8) ０．８９≦Ｌ２／〈Ｌ２〉≦１．１０Table 12 Average value of the optical film thickness of the thin film layer H of the first laminate <H1> = 183 nm Average value of the optical film thickness of the thin film layer L of the first laminate <L1> = 220 nm Second Average value of the optical film thickness of the laminated thin film layer H <H2> = 206 nm Average value of the optical film thickness of the second laminated thin film layer L <L2> = 455 nm Conditional expression (1) R1 = <L1> / <H1> = 1.20m = Q1 Conditional expression (2) R2 = <L2> / <H2> = 1.11 (m + n) = Q2 Conditional expression (3) m = 1, n = 1, m + n = 2 Conditional expression (4) M1 = <H1> = 183, M2 = <H2> = 206 R3 = M2 / M1 = 1.13 Conditional expression (5) 0.80 ≦ H1 / <H1> ≦ 1.14 Conditional expression (6) 0.91 ≦ L1 / <L1> ≦ 1.09 Conditional expression (7) 0.71 ≦ H2 / <H2> ≦ 1.38 Conditional expression (8) 0.89 ≦ L2 / <L2> ≦ 1.10.
【００７６】このような誘電体多層膜２を有する偏光ビ
ームスプリッタについて、図１に示すような光入射条件
で光透過及び光反射した場合に、波長７８０ｎｍにおけ
るＰ偏光成分の透過率をＴＰとし、Ｓ偏光成分の反射率
をＲＳとした時の偏光分離特性の角度依存性を表すグラ
フを図７に示す。With respect to the polarizing beam splitter having such a dielectric multilayer film 2, when the light is transmitted and reflected under the light incident conditions as shown in FIG. 1, the transmittance of the P-polarized light component at a wavelength of 780 nm is TP, FIG. 7 is a graph showing the angle dependence of the polarization separation characteristics when the reflectance of the S-polarized light component is RS.
【００７７】本実施例による偏光ビームスプリッタは、
偏光分離面に対する光入射角４５°を中心としたときの
小傾角側及び大傾角側の透過光において、Ｐ偏光成分の
透過率ＴＰの対称性は良好であるが、Ｐ偏光成分の透過
率ＴＰの周辺光の透過率低下が目立ち始める。The polarizing beam splitter according to this embodiment is
The transmittance TP of the P-polarized component is good in the transmitted light on the small tilt angle side and the large tilt angle side when the light incident angle with respect to the polarization separation surface is 45 °, but the transmittance TP of the P-polarized component is good. A decrease in the transmittance of ambient light starts to be noticeable.
【００７８】[0078]
【発明の効果】以上説明したように本発明に係る偏光ビ
ームスプリッタは、相対的に高屈折率の薄膜層Ｈと、相
対的に低屈折率の薄膜層Ｌを交互に積層した第１の積層
と第２の積層を含む誘電体多層膜を形成し、これらの２
つの積層における薄膜層Ｈと薄膜層Ｌの光学的膜厚の比
を異なる整数比の組み合わせとなるように構成したこと
により、偏光分離特性の光入射角度依存性を軽減するこ
とができ、これによって、集光光束中又は発散光束中に
おいて、Ｓ偏光成分の反射率とＰ偏光成分の透過率とが
共に高く非対称性が少ない極めて効率の良い偏光分離特
性を得ることができ、光ピックアップ装置等の光学系を
小型化又は簡素化することが可能となる。As described above, the polarizing beam splitter according to the present invention has a first laminated structure in which thin film layers H having a relatively high refractive index and thin film layers L having a relatively low refractive index are alternately laminated. And a dielectric multilayer film including a second lamination is formed.
By configuring the ratio of the optical film thicknesses of the thin film layer H and the thin film layer L in one stack to be a combination of different integer ratios, it is possible to reduce the dependence of the polarization separation characteristic on the light incident angle. In a condensed light beam or a divergent light beam, both the reflectance of the S-polarized light component and the transmittance of the P-polarized light component are both high, and it is possible to obtain extremely efficient polarization separation characteristics with less asymmetry. The optical system can be reduced in size or simplified.
【図１】第１の実施例の偏光ビームスプリッタの構成図
である。FIG. 1 is a configuration diagram of a polarization beam splitter according to a first embodiment.
【図２】偏光分離特性の角度依存性のグラフ図である。FIG. 2 is a graph showing the angle dependence of polarization separation characteristics.
【図３】第２の実施例の偏光分離特性の角度依存性のグ
ラフ図である。FIG. 3 is a graph showing the angle dependence of polarization separation characteristics of a second embodiment.
【図４】第３の実施例の偏光分離特性の角度依存性のグ
ラフ図である。FIG. 4 is a graph showing the angle dependence of the polarization splitting characteristic of the third embodiment.
【図５】第４の実施例の偏光分離特性の角度依存性のグ
ラフ図である。FIG. 5 is a graph showing the angle dependence of the polarization separation characteristic of the fourth embodiment.
【図６】第５の実施例の偏光分離特性の角度依存性のグ
ラフ図である。FIG. 6 is a graph showing the angle dependence of the polarization separation characteristic of the fifth embodiment.
【図７】第６の実施例の偏光分離特性の角度依存性のグ
ラフ図である。FIG. 7 is a graph showing the angle dependence of the polarization separation characteristic of the sixth embodiment.
【図８】従来例の平行光束中における偏光分離特性の波
長依存性のグラフ図である。FIG. 8 is a graph showing the wavelength dependence of the polarization separation characteristic in a parallel light beam according to a conventional example.
【図９】従来例の集光光束中における偏光分離特性のグ
ラフ図である。FIG. 9 is a graph showing polarization separation characteristics in a converged light beam of a conventional example.
１、３ 光透過性基板 ２ 誘電体多層膜 Ｉ 入射光 Ｔ 透過光 Ｒ 反射光 ＴＰ Ｐ偏光成分の透過率 ＲＳ Ｓ偏光成分の反射率 1, 3 light-transmitting substrate 2 dielectric multilayer film I incident light T transmitted light R reflected light TPP Transmittance of P-polarized component RS Reflectivity of S-polarized component
Claims (5)
と相対的に低屈折率物質から成る薄膜層Ｌとを交互に繰
り返して構成する誘電体多層膜を、２つの光透過性基板
の接合面に形成した偏光ビームスプリッタにおいて、前
記誘電体多層膜は、膜構成がＨ／Ｌ／Ｈ／Ｌ／Ｈである
第１の積層と、膜構成がＨ／Ｌ／Ｈ／Ｌ／Ｈである第２
の積層とを含み、前記第１の積層を構成する薄膜層Ｈ及
び薄膜層Ｌの光学的膜厚の平均値をそれぞれ〈Ｈ１〉及
び〈Ｌ１〉とし、前記第２の積層を構成する薄膜層Ｈ及
び薄膜層Ｌの光学的膜厚の平均値をそれぞれ〈Ｈ２〉及
び〈Ｌ２〉とし、前記平均値〈Ｈ１〉と〈Ｌ１〉の内の
小さい方を分母とする平均値〈Ｈ１〉と〈Ｌ１〉の比を
Ｒ１とし、前記平均値〈Ｈ２〉と〈Ｌ２〉の内の小さい
方を分母とする平均値〈Ｈ２〉と〈Ｌ２〉の比をＲ２と
して、これらの比Ｒ１と比Ｒ２の内の小さい方をＱ１、
大きい方をＱ２とし、ｍを１〜３までの整数、ｎを１〜
４までの整数とするときに、次式を満足することを特徴
とする偏光ビームスプリッタ。 ０. ９５ｍ≦Ｑ１≦１. ２ｍ ０. ９（ｍ＋ｎ）≦Ｑ２≦１．４（ｍ＋ｎ） ２≦ｍ＋ｎ≦５1. A thin film layer H made of a material having a relatively high refractive index.
And a thin film layer L made of a material having a relatively low refractive index are alternately repeated to form a dielectric multilayer film on a joint surface between two light-transmitting substrates. A first stack having a film configuration of H / L / H / L / H, and a second stack having a film configuration of H / L / H / L / H.
Wherein the average value of the optical film thickness of the thin film layer H and the thin film layer L constituting the first laminate is <H1> and <L1>, respectively, and the thin film layer constituting the second laminate is The average values of the optical film thicknesses of H and the thin film layer L are <H2> and <L2>, respectively, and the average values <H1> and <L1> using the smaller of the average values <H1> and <L1> as the denominator. Let L1 be the ratio of L1, and let R2 be the ratio of the average <H2> and <L2> with the smaller of the averages <H2> and <L2> as the denominator, and let R2 be the ratio of these ratios R1 and R2. The smaller one is Q1,
The larger one is Q2, m is an integer from 1 to 3, and n is 1 to
A polarizing beam splitter characterized by satisfying the following expression when the integer is up to 4. 0.95m ≦ Q1 ≦ 1.2m 0.9 (m + n) ≦ Q2 ≦ 1.4 (m + n) 2 ≦ m + n ≦ 5
さい方をＭ１とし、前記平均値〈Ｈ２〉と〈Ｌ２〉の内
の小さい方をＭ２として、これら平均値Ｍ１とＭ２の内
の小さい方を分母としたＭ１とＭ２の比をＲ３とすると
きに、次式を満足する請求項１に記載の偏光ビームスプ
リッタ。 １．０≦Ｒ３≦１．７2. A smaller one of the averages <H1> and <L1> is defined as M1, and a smaller one of the averages <H2> and <L2> is defined as M2. The polarization beam splitter according to claim 1, wherein the following formula is satisfied when the ratio of M1 and M2, with the smaller of the two being the denominator, is R3. 1.0 ≦ R3 ≦ 1.7
の任意の１つの薄膜層の光学的膜厚をＨ１とし、前記第
１の積層を構成する薄膜層Ｌの内の任意の１つの薄膜層
の光学的膜厚をＬ１とし、前記第２の積層を構成する薄
膜層Ｈの内の任意の１つの薄膜層の光学的膜厚をＨ２と
し、前記第２の積層を構成する薄膜層Ｌの内の任意の薄
膜層の光学的膜厚をＬ２としたときに、次式に示す条件
を満足する請求項１又は２に記載の偏光ビームスプリッ
タ。 ０．８０≦Ｈ１／〈Ｈ１〉≦１．１５ ０．９０≦Ｌ１／〈Ｌ１〉≦１．１０ ０．７０≦Ｈ２／〈Ｈ２〉≦１．５５ ０．８５≦Ｌ２／〈Ｌ２〉≦１．１０3. The optical film thickness of any one of the thin film layers H constituting the first laminate is H1, and any one of the thin film layers L constituting the first laminate is H1. The optical film thickness of one thin film layer is L1, the optical film thickness of any one of the thin film layers H constituting the second stack is H2, and the second stack is formed. 3. The polarizing beam splitter according to claim 1, wherein, when an optical thickness of an arbitrary thin film layer among the thin film layers L is L2, a condition represented by the following expression is satisfied. 0.80 ≦ H1 / <H1> ≦ 1.15 0.90 ≦ L1 / <L1> ≦ 1.10 0.70 ≦ H2 / <H2> ≦ 1.55 0.85 ≦ L2 / <L2> ≦ 1 .10
層Ｌの屈折率をｎl、前記光透過性基板の屈折率をｎg
、前記接合面への入射光束の主光線の入射角をθとし
たときに、前記屈折率ｎh 、ｎl 、ｎg を設計基準波長
における値とすると、次の条件式を満足する請求項１〜
３の何れか１つの請求項に記載の偏光ビームスプリッ
タ。 ０. ９≦ｎh ・ｎl ／{(ｓｉｎθ）・ｎg ・( ｎh 2 ＋
ｎl 2)1/2}≦１．１4. The refractive index of the thin film layer H is nh, the refractive index of the thin film layer L is nl, and the refractive index of the light transmitting substrate is ng.
When the angle of incidence of the chief ray of the light beam incident on the joining surface is θ, the following conditional expressions are satisfied when the refractive indices nh, nl, and ng are values at a design reference wavelength.
The polarization beam splitter according to claim 3. 0.9 ≦ nh · nl / {(sin θ) · ng · (nh 2 +
nl 2 ) 1/2 } ≦ 1.1
成する薄膜層Ｈを同一成分の物質から成る薄膜層とし、
前記第１の積層及び前記第２の積層を構成する薄膜層Ｌ
を同一成分の物質から成る薄膜層とした請求項１〜４の
何れか１つの請求項に記載の偏光ビームスプリッタ。5. The thin film layers H constituting the first laminate and the second laminate are thin film layers made of the same component material,
The thin film layer L constituting the first stack and the second stack
The polarizing beam splitter according to any one of claims 1 to 4, wherein? Is a thin film layer made of a substance having the same component.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11176065A JP2001004840A (en) | 1999-06-22 | 1999-06-22 | Polarizing beam splitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11176065A JP2001004840A (en) | 1999-06-22 | 1999-06-22 | Polarizing beam splitter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001004840A true JP2001004840A (en) | 2001-01-12 |
Family
ID=16007111
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11176065A Pending JP2001004840A (en) | 1999-06-22 | 1999-06-22 | Polarizing beam splitter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001004840A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7163291B2 (en) | 2002-12-03 | 2007-01-16 | Essilor International (Compagnie Generale D'optique) | Polarization splitter, method of manufacturing same and ophthalmic lens incorporating projection inserts containing it |
| US7414785B2 (en) | 2000-02-24 | 2008-08-19 | Asml Holding N.V. | Ultraviolet polarization beam splitter with minimum apodization |
| JP2008293029A (en) * | 2003-06-11 | 2008-12-04 | Asml Holding Nv | Ultraviolet polarization beam splitter with minimum apodization |
| CN113167962A (en) * | 2018-12-07 | 2021-07-23 | 3M创新有限公司 | Optical film and polarizing beam splitter |
-
1999
- 1999-06-22 JP JP11176065A patent/JP2001004840A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7414785B2 (en) | 2000-02-24 | 2008-08-19 | Asml Holding N.V. | Ultraviolet polarization beam splitter with minimum apodization |
| US7163291B2 (en) | 2002-12-03 | 2007-01-16 | Essilor International (Compagnie Generale D'optique) | Polarization splitter, method of manufacturing same and ophthalmic lens incorporating projection inserts containing it |
| JP2008293029A (en) * | 2003-06-11 | 2008-12-04 | Asml Holding Nv | Ultraviolet polarization beam splitter with minimum apodization |
| CN113167962A (en) * | 2018-12-07 | 2021-07-23 | 3M创新有限公司 | Optical film and polarizing beam splitter |
| CN113167962B (en) * | 2018-12-07 | 2023-09-29 | 3M创新有限公司 | Optical film and polarizing beam splitter |
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