JP2828604B2 - Birefringence measurement device - Google Patents
Birefringence measurement deviceInfo
- Publication number
- JP2828604B2 JP2828604B2 JP5904895A JP5904895A JP2828604B2 JP 2828604 B2 JP2828604 B2 JP 2828604B2 JP 5904895 A JP5904895 A JP 5904895A JP 5904895 A JP5904895 A JP 5904895A JP 2828604 B2 JP2828604 B2 JP 2828604B2
- Authority
- JP
- Japan
- Prior art keywords
- birefringence
- sample
- component
- optical
- axis direction
- 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.)
- Expired - Fee Related
Links
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、複屈折測定装置に係
り、特に試料の複屈折位相差及びその主軸方位を高速で
測定する複屈折測定装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a birefringence measuring apparatus, and more particularly to a birefringence measuring apparatus for measuring a birefringence phase difference of a sample and its principal axis direction at a high speed.
【０００２】[0002]
【従来の技術】近年、光エロクトロニクス機器の発達に
伴い、光学素子、ＬＣＤ、ＭＯ等の光デバイスの高精度
化が要求されるようになってきた。特に、この光デバイ
スの品質を評価する上で光学的均一性が重要とされてい
るため、光デバイスに残留する応力に起因した複屈折を
高精度に測定する必要性が高まっている。2. Description of the Related Art In recent years, with the development of optical erotic devices, it has been required to increase the precision of optical devices such as optical elements, LCDs, and MOs. In particular, since optical uniformity is important in evaluating the quality of the optical device, there is an increasing need to measure birefringence caused by stress remaining in the optical device with high accuracy.
【０００３】このように複屈折を高精度に測定する複屈
折測定装置としては、例えば光源に直交偏光２周波レー
ザを採用した光ヘテロダイン複屈折測定法（例えば、特
公昭５９−５０９２７）により複屈折位相差を測定する
ものが知られている。更に、この複屈折位相差だけでな
くその主軸方位も同時に測定する複屈折測定装置とし
て、光源に周波数安定化横ゼーマンレーザ（「Stabiliz
ed Transverse ZeemanLaser」、略して「ＳＴＺＬ」と
も呼ぶ）を用いた方法も知られている（例えば、特公平
６−１２３３３）。As a birefringence measuring apparatus for measuring birefringence with high precision as described above, for example, birefringence is measured by an optical heterodyne birefringence measuring method (for example, Japanese Patent Publication No. 59-50927) employing a two-frequency orthogonally polarized laser as a light source. A device for measuring a phase difference is known. Furthermore, as a birefringence measuring device that simultaneously measures not only the birefringence phase difference but also the principal axis direction, a frequency stabilized lateral Zeeman laser ("Stabiliz
ed Transverse ZeemanLaser ”(also referred to as“ STZL ”for short) is also known (for example, Japanese Patent Publication No. 6-12333).
【０００４】しかしながら、周波数安定化横ゼーマンレ
ーザを用いた上述の複屈折測定装置は、複屈折主軸方位
を同時に測定する目的で２分の１波長板等の光学系を回
転させる構成であったため、測定時間がやや遅くなると
いった不都合があった。However, the above-described birefringence measuring apparatus using a frequency-stabilized transverse Zeeman laser has a structure in which an optical system such as a half-wave plate is rotated for the purpose of simultaneously measuring the birefringent principal axis directions. There was an inconvenience that the measurement time was slightly delayed.
【０００５】そこで、測定時間の短縮化を図る複屈折測
定装置として、周波数安定化横ゼーマンレーザとロック
インアンプを組み合わせたものが提案されている（例え
ば、特開平５−２４９０３１）。この複屈折測定装置に
よると、１点あたりの測定時間が２（ｍｓ）と高速化が
図られている。Therefore, as a birefringence measuring device for shortening the measuring time, a device combining a frequency-stabilized transverse Zeeman laser and a lock-in amplifier has been proposed (for example, Japanese Patent Laid-Open No. 5-249031). According to this birefringence measuring apparatus, the measurement time per point is increased to 2 (ms) and the speed is increased.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、上記測
定時間の短縮化を図った複屈折測定装置にあっては、検
出対象のレーザ光の光路を２つに分けて、その２つの光
路の夫々に複数の偏光素子や検出器、ロックインアンプ
等を割り当てて配置する構成であったため、光学系だけ
でなく装置全体の構成も複雑になるといった問題があっ
た。However, in the birefringence measuring apparatus in which the measurement time is shortened, the optical path of the laser light to be detected is divided into two paths, and each of the two paths is separated. Since the configuration is such that a plurality of polarizing elements, detectors, lock-in amplifiers and the like are allocated and arranged, there is a problem that not only the optical system but also the configuration of the entire apparatus becomes complicated.
【０００７】本発明は、上述の従来技術の問題を考慮し
てなされたものであり、測定時間の短縮化を図ると共
に、装置全体の構成を簡素に構築できる複屈折測定装置
を提供することを、目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a birefringence measuring apparatus capable of shortening the measuring time and simplifying the configuration of the entire apparatus. , Aim.
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するため
に、請求項１記載の発明に係る複屈折測定装置は、レー
ザ光により測定対象の試料の複屈折状態に関する情報を
測定する構成とし、２つの互いに異なる周波数成分を有
し且つその２つの周波数成分が互いに反対向きの円偏光
となるレーザ光を発振する光源と、この光源による当該
レーザ光を上記試料に向けて発振させることにより当該
試料の上記複屈折状態を反映したレーザ光の光信号を検
出する検出手段と、この検出手段により検出された当該
光信号に基づいて上記試料の少なくとも複屈折位相差及
び複屈折主軸方位を同時に計測する計測手段とを備えて
いる。To achieve the above object, a birefringence measuring apparatus according to the first aspect of the present invention is configured to measure information on a birefringence state of a sample to be measured by a laser beam, A light source that oscillates a laser beam having two different frequency components and the two frequency components are circularly polarized in opposite directions, and oscillating the laser beam by the light source toward the sample to produce the sample. Detecting means for detecting an optical signal of laser light reflecting the birefringence state, and simultaneously measuring at least a birefringence phase difference and a birefringent principal axis direction of the sample based on the optical signal detected by the detecting means. Measuring means.
【０００９】また請求項２記載の発明では、前記光源は
２つの互いに異なる周波数成分を有し且つその２つの周
波数成分が互いに直交した直線偏光となるレーザ光を発
振するレーザと４分の１波長板とを組み合わせて成って
いる。According to the second aspect of the present invention, the light source has a laser having two different frequency components and a laser which oscillates a laser beam in which the two frequency components are linearly polarized light orthogonal to each other. Combined with a board.
【００１０】また請求項３記載の発明では、前記レーザ
は周波数安定化横ゼーマンレーザである。[0010] In the invention according to claim 3, the laser is a frequency stabilized transverse Zeeman laser.
【００１１】また請求項４記載の発明では、前記検出手
段は、前記光源により発振された上記レーザ光の当該２
つの周波数成分を前記試料を介して光学的に相互に干渉
させる光学系と、この光学系からの干渉後の光ビート成
分を含むレーザ光の光信号を電気信号に変換して検出す
る光電検出器とを備えている。Further, in the invention described in claim 4, the detecting means is configured to detect the second one of the laser light oscillated by the light source.
An optical system for optically interfering two frequency components with each other through the sample, and a photoelectric detector for converting an optical signal of a laser beam containing an optical beat component after interference from the optical system into an electric signal and detecting the electric signal And
【００１２】また請求項５記載の発明では、前記光学系
は、前記光源から入射されたレーザ光の２つの周波数成
分の夫々における偏光状態の位相を９０度変換する４分
の１波長板と、この４分の１波長板を介して入射される
レーザ光の上記２つの周波数成分を相互に干渉させ且つ
その干渉させて得られる光ビート成分を含むレーザ光を
出射する直線偏光子とを備え、上記光源及び４分の１波
長板間の光路上に前記試料を配置するように形成してい
る。Further, in the invention according to claim 5, the optical system includes: a quarter-wave plate for converting a phase of a polarization state of each of two frequency components of the laser light incident from the light source by 90 degrees; A linear polarizer that emits laser light including a light beat component obtained by causing the two frequency components of the laser light incident through the quarter-wave plate to interfere with each other and causing the interference, The sample is arranged on the optical path between the light source and the quarter-wave plate.
【００１３】また請求項６記載の発明は、前記４分の１
波長板を前記レーザ光の光軸に直交する面内の光軸を中
心として予め設定された基準方位に対して進相軸方位が
４５度となる位置に配置する一方、前記直線偏光子を上
記基準方位に対して偏光透過軸方位が０度となる位置に
配置している。The invention according to claim 6 is the one-fourth aspect.
While disposing the wave plate at a position where the fast axis direction is 45 degrees with respect to a preset reference direction around an optical axis in a plane perpendicular to the optical axis of the laser light, the linear polarizer is It is arranged at a position where the polarization transmission axis direction is 0 degrees with respect to the reference direction.
【００１４】また請求項７記載の発明では、前記光電検
出器はフォトダイオードである。Further, in the invention according to claim 7, the photoelectric detector is a photodiode.
【００１５】また請求項８記載の発明では、前記計測手
段は、前記光電検出器が検出した電気信号から直流成分
を抽出するローパスフィルタと、上記光電検出器が検出
した電気信号から前記光ビート成分に相当する交流成分
を抽出するロックインアンプと、上記ローパスフィルタ
により抽出された直流成分及び上記ロックインアンプに
より抽出された交流成分に基づいて前記試料の複屈折位
相差及び複屈折主軸方位を同時に演算する演算部とを備
えている。Further, in the invention according to claim 8, the measuring means includes a low-pass filter for extracting a DC component from the electric signal detected by the photoelectric detector, and the optical beat component from the electric signal detected by the photoelectric detector. A lock-in amplifier that extracts an AC component corresponding to the above, and a birefringence phase difference and a birefringent principal axis direction of the sample are simultaneously determined based on the DC component extracted by the low-pass filter and the AC component extracted by the lock-in amplifier. And a calculation unit for calculating.
【００１６】また請求項９記載の発明では、前記演算部
は、前記交流成分に相当する２つの直交成分をＩｘ及び
Ｉｙとし、前記直流成分をＩDCとし、前記試料の複屈折
位相差をΔとし、その複屈折主軸方位をψとしたとき、
この複屈折位相差Δ及び複屈折主軸方位ψを、According to the ninth aspect of the present invention, the arithmetic unit includes two orthogonal components corresponding to the AC component as Ix and Iy, the DC component as I DC, and a birefringence phase difference of the sample as ΔC. And when the birefringent principal axis direction is ψ,
This birefringent phase difference Δ and birefringent principal axis direction ψ
【数３】 の計算式で演算するアルゴリズムを実行するように予め
設定された演算器を備えている。(Equation 3) Is provided in advance so as to execute an algorithm that operates using the calculation formula.
【００１７】また請求項１０記載の発明は、前記演算部
により同時に演算された前記試料の複屈折位相差及び複
屈折主軸方位を出力する出力デバイスを、前記計測手段
が更に備えている。According to a tenth aspect of the present invention, the measuring means further includes an output device for outputting the birefringence phase difference and the birefringent principal axis direction of the sample calculated simultaneously by the calculation unit.
【００１８】さらに、請求項１１記載の発明に係る複屈
折測定装置は、レーザ光により測定対象の試料の複屈折
状態に関する情報を測定する構成とし、２つの互いに異
なる周波数成分を有し且つその２つの周波数成分が互い
に反対向きの円偏光となるレーザ光を発振する光源と、
この光源から上記試料を介して入射されたレーザ光の２
つの周波数成分の夫々における偏光状態の位相を９０度
変換する４分の１波長板と、この４分の１波長板を介し
て入射されたレーザ光の上記２つの周波数成分を相互に
干渉させ且つその干渉させて得られる光ビート成分を含
むレーザ光を出射する直線偏光子と、この直線偏光子を
介して入射されたレーザ光の光信号を電気信号に変換し
て検出する光電検出器と、この光電検出器が検出した電
気信号から直流成分を抽出するローパスフィルタと、上
記光電検出器が検出した電気信号から上記光ビート成分
に相当する交流成分を抽出するロックインアンプと、上
記ローパスフィルタにより抽出された直流成分及び上記
ロックインアンプにより抽出された交流成分に基づいて
上記試料の複屈折位相差及び複屈折主軸方位を同時に演
算する演算部とを備えると共に、上記演算部は、上記直
流成分をＩDCとし、上記交流成分に相当する２つの直交
成分をＩｘ及びＩｙとし、上記試料の複屈折位相差をΔ
とし、その複屈折主軸方位をψとしたとき、その複屈折
位相差Δ及び複屈折主軸方位ψを、Further, the birefringence measuring apparatus according to the present invention is configured to measure information on a birefringence state of a sample to be measured by a laser beam, and has two different frequency components and has two different frequency components. A light source that oscillates laser light in which two frequency components are circularly polarized in opposite directions,
2 of laser light incident from the light source through the sample
A quarter-wave plate for converting the phase of the polarization state of each of the two frequency components by 90 degrees, and causing the two frequency components of the laser light incident through the quarter-wave plate to interfere with each other; A linear polarizer that emits a laser beam containing a light beat component obtained by the interference, and a photoelectric detector that converts an optical signal of the laser beam incident through the linear polarizer into an electric signal and detects the electric signal, A low-pass filter that extracts a DC component from the electric signal detected by the photoelectric detector, a lock-in amplifier that extracts an AC component corresponding to the optical beat component from the electric signal detected by the photoelectric detector, and the low-pass filter. A calculating unit for simultaneously calculating the birefringence phase difference and the birefringent principal axis direction of the sample based on the extracted DC component and the AC component extracted by the lock-in amplifier. With obtaining, the calculating unit, the DC component and I DC, the two orthogonal components corresponding to the AC component and Ix and Iy, a birefringence phase difference of the sample Δ
When the birefringent principal axis direction is ψ, the birefringent phase difference Δ and the birefringent principal axis direction ψ are
【数４】 の計算式で演算するように設定されている。(Equation 4) It is set to calculate by the calculation formula.
【００１９】さらに請求項１２記載の発明では、前記光
源は軸ゼーマンレーザから成っている。Further, in the twelfth aspect, the light source comprises an axial Zeeman laser.
【００２０】[0020]
【作用】請求項１〜１２記載の発明に係る複屈折測定装
置は、光源により２つの互いに異なる周波数成分を有し
且つその２つの周波数成分が互いに反対向きの円偏光と
なるレーザ光が発振される。そして、検出手段により試
料の複屈折状態を反映したレーザ光の光信号が検出され
ると、計測手段により光信号に基づいて試料の少なくと
も複屈折位相差及び複屈折主軸方位が同時に計測され
る。In the birefringence measuring apparatus according to the first to twelfth aspects of the present invention, a laser beam having two different frequency components and the two frequency components being circularly polarized in mutually opposite directions is oscillated by the light source. You. Then, when the optical signal of the laser light reflecting the birefringence state of the sample is detected by the detecting means, at least the birefringence phase difference and the birefringent principal axis direction of the sample are simultaneously measured based on the optical signal by the measuring means.
【００２１】[0021]
【実施例】以下、本発明の一実施例を図１〜図８に基づ
き説明する図１に示す複屈折測定装置は、光ビート成分
を担う光信号に基づいて複屈折情報を測定する光ヘテロ
ダイン複屈折測定法を適用したもので、左右円偏光２周
波レーザ光（以下、単に「２周波円偏光」と呼ぶ）Ｌを
発振する光源１と、この光源１で発振される２周波円偏
光Ｌにより、測定対象である試料Ｓａの複屈折状態に関
する情報を取得するための検出測定部２とを備えてい
る。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 8. The birefringence measuring apparatus shown in FIG. 1 is an optical heterodyne which measures birefringence information based on an optical signal carrying an optical beat component. A birefringence measurement method is applied, and a light source 1 oscillating left and right circularly polarized two-frequency laser light (hereinafter, simply referred to as “two-frequency circularly polarized light”) L, and a two-frequency circularly polarized light L oscillated by the light source 1 And a detection / measurement unit 2 for acquiring information on the birefringence state of the sample Sa to be measured.
【００２２】光源１は、直交直線偏光２周波レーザであ
る周波数安定化横ゼーマンレーザ（以下、「ＳＴＺＬ」
と略称する）１ａと４分の１波長板１ｂとを組み合わせ
た構成で、ＳＴＺＬ１ａが生成する２周波直交直線偏光
を４分の１波長板１ｂを介して、２つの異なる周波数成
分（ｆ１、ｆ２）が互いに反対向きの円偏光（右回り及
び左回り）となる２周波円偏光Ｌに変換して発振させる
ようになっている。従って、この光源１は、２つの異な
る周波数成分の夫々が光軸を中心として互いに反対向き
に回転する２周波円偏光Ｌを、検出測定部２に向けて発
振するようになっている。The light source 1 is a frequency-stabilized transverse Zeeman laser (hereinafter referred to as "STZL") which is an orthogonal linearly polarized two-frequency laser.
In this configuration, the two-frequency orthogonal linearly polarized light generated by the STZL 1a is converted into two different frequency components (f1, f2) via the quarter-wave plate 1b. ) Is converted into two-frequency circularly polarized light L that becomes circularly polarized light (clockwise and counterclockwise) in opposite directions to oscillate. Accordingly, the light source 1 oscillates the two-frequency circularly polarized light L in which two different frequency components rotate in opposite directions about the optical axis toward the detection and measurement unit 2.
【００２３】検出測定部２は、試料Ｓａの複屈折状態を
反映する光ビート成分（周波数をωとしたとき、周波数
ωは２つの周波数成分の差（ω＝ｆ１−ｆ２）で表され
る）を担う光信号を検出するための検出部３（本発明の
検出手段を成す）と、この検出部３により検出された光
信号に基づいて試料Ｓａの複屈折を計測するための計測
部４（本発明の計測手段を成す）とを備えている。The detection / measurement unit 2 detects an optical beat component reflecting the birefringence state of the sample Sa (when the frequency is ω, the frequency ω is represented by a difference between two frequency components (ω = f1−f2)). And a measuring unit 4 for measuring the birefringence of the sample Sa based on the optical signal detected by the detecting unit 3 (which constitutes the detecting means of the present invention). (Measuring means of the present invention).
【００２４】検出部３は、光源１の出射側の共通光路上
に配置される試料搭載用の試料ステージ５、偏光素子か
ら成る光学系６、及び光電検出器７を備えている。The detecting section 3 includes a sample stage 5 for mounting a sample, which is arranged on a common optical path on the emission side of the light source 1, an optical system 6 including a polarizing element, and a photoelectric detector 7.
【００２５】試料ステージ５は、例えばＸＹステージか
ら成り、試料Ｓａの測定位置を光軸方向に直交する面内
での互いに直交する２方向の夫々に沿って自動又は手動
で可変設定できるようになっている。ここで、光源１か
らの２周波円偏光Ｌが試料Ｓａを透過する場合を考える
と、２つの周波数成分の夫々は、試料Ｓａが有する２つ
の主軸間の屈折率差に起因して生じる位相ずれにより楕
円偏光化する。従って、この楕円偏光化した２周波偏光
成分を担うレーザ光Ｌ１は、試料Ｓａの持つ複屈折位相
差（複屈折の大きさ）及びその主軸方位（複屈折の方
向）の情報を反映した光信号として次段の光学系６に出
射される。The sample stage 5 is composed of, for example, an XY stage, so that the measurement position of the sample Sa can be automatically or manually variably set along each of two directions orthogonal to each other in a plane orthogonal to the optical axis direction. ing. Here, considering the case where the two-frequency circularly polarized light L from the light source 1 passes through the sample Sa, each of the two frequency components has a phase shift caused by a refractive index difference between two main axes of the sample Sa. Into elliptically polarized light. Therefore, the laser light L1 carrying the elliptically polarized two-frequency polarization component reflects an optical signal reflecting information on the birefringence phase difference (birefringence magnitude) and the principal axis direction (birefringence direction) of the sample Sa. Is emitted to the optical system 6 in the next stage.
【００２６】光学系６は、光軸方向に直交する面内の光
軸を中心として予め設定された基準方位（例えば、光源
１のＳＴＺＬ１ａが生成する互いに直交する直線偏光の
偏波面の２方向（ｘ方向及びｙ方向）の内の一方）に対
して進相軸方位が４５度となるように配置される４分の
１波長板６ａと、その４分の１波長板６ａの出射側に上
記基準方位に対して偏光透過軸方位が０度となるように
配置される直線偏光子６ｂとを備えている。The optical system 6 has a predetermined reference direction centered on an optical axis in a plane orthogonal to the optical axis direction (for example, two directions of mutually orthogonal linearly polarized planes of polarization generated by the STZL 1a of the light source 1). a quarter-wave plate 6a arranged so that the fast axis direction is 45 degrees with respect to one of the x-direction and the y-direction), and the above-mentioned quarter-wave plate 6a on the emission side. A linear polarizer 6b disposed so that the polarization transmission axis direction is 0 degrees with respect to the reference direction.
【００２７】これら構成により、この光学系６は、試料
Ｓａからのレーザ光Ｌ１の２周波偏光成分間の位相差を
保った状態で、その２周波偏光成分の夫々における偏光
状態の位相を４分の１波長板６ａにて９０度変換させる
と共に、その変換後のレーザ光Ｌ２の２周波偏光成分を
直線偏光子６ｂにて相互に干渉させて光ビート成分を生
成させる。この光ビート成分は、２つの周波数成分の差
の周波数ωで振動する「うなり成分」であると共に、上
記基準方位に基づいた試料Ｓａの複屈折位相差及びその
主軸方位に関する位相ずれ及び振幅変化を含む光信号と
なっている。要するに、光ビート成分の振幅と位相の情
報に試料Ｓａの複屈折位相差及び主軸方位が含まれてい
る。With these configurations, the optical system 6 maintains the phase difference between the two-frequency polarization components of the laser beam L1 from the sample Sa, and changes the phase of the polarization state in each of the two-frequency polarization components by four minutes. Is converted by 90 degrees by the one-wave plate 6a, and the two-wave polarization components of the converted laser light L2 are caused to interfere with each other by the linear polarizer 6b to generate an optical beat component. This optical beat component is a “beat component” that oscillates at the frequency ω of the difference between the two frequency components, and also determines the birefringence phase difference of the sample Sa based on the reference orientation and the phase shift and amplitude change with respect to the principal axis orientation. Optical signal. In short, the information on the amplitude and phase of the optical beat component includes the birefringence phase difference and the principal axis direction of the sample Sa.
【００２８】従って、直線偏光子６ｂからのレーザ光Ｌ
３は、干渉により生じた光ビート成分に試料Ｓａの複屈
折位相差及びその主軸方位を含む光信号として次段の光
電検出器７に出射される。Therefore, the laser beam L from the linear polarizer 6b
Reference numeral 3 denotes an optical signal containing the birefringence phase difference of the sample Sa and the principal axis direction thereof in the optical beat component generated by the interference, and is emitted to the next-stage photoelectric detector 7.
【００２９】光電検出器７は、フォトダイオード等のフ
ォトディテクタ（ＰＤ）から成り、直線偏光子６ｂから
のレーザ光Ｌ３の光信号を検出し、その光信号の光強度
に相当する検出信号（光電流）Ｓ１０をプリアンプ（図
示しない）等を介して計測部４にリアルタイムに出力す
る。The photoelectric detector 7 comprises a photodetector (PD) such as a photodiode, detects an optical signal of the laser beam L3 from the linear polarizer 6b, and detects a detection signal (photocurrent) corresponding to the light intensity of the optical signal. 3.) S10 is output in real time to the measuring unit 4 via a preamplifier (not shown).
【００３０】計測部４は、光源１から供給される光ビー
ト成分（試料入射前のそれと同じ）の周波数ω及び基準
位相を担う参照ビート信号Ｓ２０を受けて、光電検出器
７からの検出信号Ｓ１０の内の光ビート成分に相当する
交流成分Ｉｘ及びＩｙ（後述）を抽出するロックインア
ンプ８と、検出信号Ｓ１０の内の直流成分ＩDC（後述）
を抽出するローパスフィルタ９と、交流成分Ｉｘ、Ｉｙ
及び直流成分ＩDCに基づいて試料Ｓａの複屈折を演算す
る演算部１０とを備えている。The measuring section 4 receives the frequency ω of the optical beat component (same as that before the sample is incident) supplied from the light source 1 and the reference beat signal S20 bearing the reference phase, and receives the detection signal S10 from the photoelectric detector 7 AC component Ix and Iy corresponding to optical beat component of the lock-in amplifier 8 to extract (described later), the DC component I DC of the detection signal S10 (described later)
And the AC components Ix and Iy
And a calculation unit 10 for calculating the birefringence of the sample Sa based on the DC component I DC .
【００３１】この内、演算部１０は、演算装置（演算
器）としてのＣＰＵ１１を要部とするコンピュータ（図
示しない）を搭載して成り、そのＣＰＵ１１が予め設定
された演算アルゴリズムを実行することにより、複屈折
位相差Δ及びその主軸方位ψ（後述）を演算するように
なっている。この演算部１０には、演算結果の表示等を
行うモニタ、プリンタ等の出力デバイス１４が接続され
ている。The arithmetic unit 10 includes a computer (not shown) having a CPU 11 as an arithmetic unit (arithmetic unit) as a main part, and the CPU 11 executes a predetermined arithmetic algorithm. , Birefringence phase difference Δ and its principal axis direction ψ (described later) are calculated. The computing unit 10 is connected to an output device 14 such as a monitor, a printer, or the like for displaying a computation result.
【００３２】ここで、本発明に係る複屈折測定原理を説
明する。まず、本実施例に係る複屈折測定装置におい
て、光電検出器７からの検出信号Ｓ１０の信号特性を求
めるため、ストークスパラメータとミューラー行列とに
よる偏光の計算（例えば、応用物理学会・光学懇話会編
「結晶光学 第５章」 森北出版）を行った。Here, the principle of birefringence measurement according to the present invention will be described. First, in the birefringence measuring apparatus according to the present embodiment, in order to obtain the signal characteristics of the detection signal S10 from the photoelectric detector 7, the polarization is calculated using the Stokes parameter and the Mueller matrix (for example, edited by the Japan Society of Applied Physics and Optical Society) "Crystal Optics Chapter 5" Morikita Publishing).
【００３３】ストークスパラメータは、光の２方向（ｘ
及びｙ）の電界成分Ｅｘ、Ｅｙに基づいた４つの成分を
１組として偏光特性を記述するものである。一般に、光
軸に直交する面内の２方向の電界成分Ｅｘ及びＥｙの２
方向の振幅、周波数、位相の夫々をａｘ及びａｙ、ｆｘ
及びｆｙ、φｘ及びφｙとし、位相差をΦとしたとき、
ストークスパラメータの４つの成分（光強度成分をＳ
０、水平垂直直線偏光成分をＳ１、±４５度直線偏光成
分をＳ２、及び左右円偏光成分をＳ３とする）は、次式
で表現される。The Stokes parameter is calculated in two directions (x
And y) describe polarization characteristics as a set of four components based on the electric field components Ex and Ey. Generally, the electric field components Ex and Ey in two directions in a plane orthogonal to the optical axis
Ax, ay, and fx represent the amplitude, frequency, and phase of the
And fy, φx and φy, and the phase difference is Φ,
The four components of the Stokes parameter (the light intensity component is S
0, the horizontal and vertical linearly polarized light components are S1, the ± 45-degree linearly polarized light component is S2, and the left and right circularly polarized light components are S3).
【００３４】[0034]
【数５】 この（１）〜（４）式で表されるストークスパラメータ
の４つの成分は、理論値としてだけでなく実測値として
実験的にも確認できるものである。(Equation 5) The four components of the Stokes parameters represented by the equations (1) to (4) can be experimentally confirmed not only as theoretical values but also as actual measured values.
【００３５】ミューラー行列は、４分の１波長板等の各
種の偏光素子を入射光から出射光への偏光特性の変換を
行う素子、即ち上記４つの成分（以下、「１行×４列
（Ｓ０…Ｓ３）」の行例［Ｓ］で表す）の内の少なくと
も１つを変換させる素子と見做した際の、偏光素子の偏
光特性及び光学的配置状態で定まる［４行×４列］の行
列（以下、便宜上［Ｍ］と表す）である。The Mueller matrix is an element that converts various polarization elements such as a quarter-wave plate into a polarization characteristic from incident light to outgoing light, that is, the above four components (hereinafter referred to as “1 row × 4 columns ( S0... S3)), which is determined by the polarization characteristics and the optical arrangement of the polarizing element when at least one of the row examples [S] is determined to be a conversion element [4 rows × 4 columns] (Hereinafter referred to as [M] for convenience).
【００３６】そこで、本実施例に係る複屈折測定装置で
の光学的構成（光源１、試料Ｓａ、光学系６）におい
て、最終的に光電検出器７で検出されるレーザ光Ｌ３の
ストークスパラメータを［Ｓ］とし、光源１（ＳＴＺＬ
１ａ及び４分の１波長板１ｂ）の２周波円偏光Ｌにより
表現されるストークスパラメータを［Ｓ１］とし、試料
Ｓａのミューラー行列を［Ｍ１］とし、光学系３の４分
の１波長板６ａ及び直線偏光子６ｂのミューラー行列を
夫々［Ｍ２］及び［Ｍ３］としたとき、ストークスパラ
メータ［Ｓ］は次のベクトル計算式により求まる。Therefore, in the optical configuration (light source 1, sample Sa, optical system 6) of the birefringence measuring apparatus according to the present embodiment, the Stokes parameter of the laser beam L3 finally detected by the photoelectric detector 7 is changed. [S], and light source 1 (STZL
The Stokes parameter expressed by the two-frequency circularly polarized light L of the 1a and quarter-wave plates 1b) is [S1], the Mueller matrix of the sample Sa is [M1], and the quarter-wave plate 6a of the optical system 3 is When the Mueller matrix of the linear polarizer 6b is [M2] and [M3], respectively, the Stokes parameter [S] is obtained by the following vector calculation formula.
【００３７】[0037]
【数６】 この（５）式によるストークスパラメータ［Ｓ］の内の
光強度成分、即ち検出信号Ｓ１０に相当する成分Ｓ０
は、ベクトル計算結果（便宜上、途中計算式を省略）に
より、試料Ｓａの複屈折位相差Δ及びその主軸方位ψ
と、光源１の２周波円偏光Ｌのｘ、ｙ方向の振幅ａｘ、
ａｙ及びその周波数差ωとから、(Equation 6) The light intensity component of the Stokes parameter [S] according to the equation (5), that is, the component S0 corresponding to the detection signal S10.
Is the birefringence phase difference Δ of the sample Sa and its principal axis direction ψ, based on the vector calculation results (intermediate calculation formulas are omitted for convenience).
And the amplitude ax of the two-frequency circularly polarized light L of the light source 1 in the x and y directions,
ay and its frequency difference ω,
【数７】 の演算式で求まることが確認された。(Equation 7) It was confirmed that it could be obtained by the operation formula.
【００３８】そこで、上記（６）式で算出される光強度
成分Ｓ０に相当する検出信号Ｓ１０の内のローパスフィ
ルタ９で抽出される直流成分をＩDCとし、ロックインア
ンプ８で抽出される交流成分の内の直交成分をＩｘ、Ｉ
ｙとしたとき、直流成分ＩDC及び交流成分Ｉｘ、Ｉｙは
次のようになる。Therefore, the DC component extracted by the low-pass filter 9 in the detection signal S10 corresponding to the light intensity component S0 calculated by the above equation (6) is defined as I DC, and the AC extracted by the lock-in amplifier 8 The orthogonal components among the components are Ix, I
When y is set, the DC component I DC and the AC components Ix and Iy are as follows.
【００３９】[0039]
【数８】 (Equation 8)
【００４０】従って、試料Ｓａの複屈折位相差Δ及びそ
の主軸方位ψは、ａｘ＝ａｙとしたとき、（７）〜
（９）式から、次の算出式で求めることができる。Therefore, the birefringence phase difference Δ and the principal axis direction の of the sample Sa are given by (7) to (7) when ax = ay.
From equation (9), it can be obtained by the following equation.
【００４１】[0041]
【数９】 (Equation 9)
【００４２】ここで、実施例に戻り、演算部１０の処理
を説明すると、演算部１０は、検出信号Ｓ１０中の直流
成分ＩDC及び交流成分Ｉｘ、ＩｙをＡ／Ｄ変換器等のイ
ンタフェース（図示しない）を介してデジタル量として
取り込むと、予め上記（１０）及び（１１）式に基づい
て設定された演算アルゴリズムを実行することにより、
試料Ｓａの複屈折位相差Δ及び複屈折主軸方位ψを演算
する。Now, returning to the embodiment, the processing of the arithmetic unit 10 will be described. The arithmetic unit 10 converts the DC component I DC and the AC components Ix and Iy in the detection signal S10 into an interface such as an A / D converter. (Not shown) as a digital quantity, by executing an arithmetic algorithm set in advance based on the above equations (10) and (11),
The birefringence phase difference Δ and the birefringent principal axis direction の of the sample Sa are calculated.
【００４３】次に、上記のように演算される複屈折位相
差及びその主軸方位の有効性に関する検証実験を試み
た。この検証実験の結果を図２〜図５に基づいて説明す
る。ここで、この検証実験にはバビネソレイユ補償器
（以下、「ＢＳＣ」と略称する）を試料として採用し
た。Next, a verification experiment was conducted on the validity of the birefringence phase difference calculated as described above and the principal axis direction thereof. The results of this verification experiment will be described with reference to FIGS. Here, a Babinet Soleil compensator (hereinafter abbreviated as “BSC”) was used as a sample in this verification experiment.
【００４４】図２は、複屈折位相差の有効性に関する検
証実験の結果を説明するものである。同図に示す検証実
験は、ＢＳＣの主軸方位を一定にした状態で、そのＢＳ
Ｃの複屈折位相差を変えたとき、即ちＢＳＣのマイクロ
メータの送りを変化させたときに得られる測定値を校正
値と比較するものである。この比較結果から、同図に示
す如く、実線で示した校正値の変化直線と○印で示した
測定値とがほぼ一致していることが確認された。FIG. 2 illustrates the results of a verification experiment on the effectiveness of the birefringence phase difference. In the verification experiment shown in the figure, the BS axis was kept constant and the BS
The measured value obtained when the birefringence phase difference of C is changed, that is, when the feed of the micrometer of the BSC is changed, is compared with a calibration value. From this comparison result, as shown in the figure, it was confirmed that the change straight line of the calibration value indicated by the solid line and the measured value indicated by the mark almost matched.
【００４５】図３は、複屈折位相差の最小検出限界に関
する検証実験の結果を説明するものである。同図に示す
検証実験は、試料を配置しない状態で連続して１０回の
複屈折位相差を測定したものである。この測定結果によ
り、同図に示す如く、最小検出限界の平均値が約０．０
５４度（deg ）であることが確認された。FIG. 3 illustrates the result of a verification experiment on the minimum detection limit of the birefringence phase difference. In the verification experiment shown in the figure, the birefringence phase difference was measured 10 times continuously without any sample placed. As a result of this measurement, as shown in FIG.
It was confirmed that the angle was 54 degrees (deg).
【００４６】図４は、複屈折主軸方位の有効性に関する
検証実験の結果を説明するものである。同図に示す検証
実験は、ＢＳＣの複屈折位相差を一定にした状態で、Ｂ
ＳＣの主軸方位を変えたときの測定値を理想値と比較す
るものである。この比較結果から、同図に示す如く、Ｂ
ＳＣの変化させた複屈折主軸方位の理想値直線と測定値
とがほぼ一致しており、その測定誤差が約±１．２度
（deg ）であることが確認された。FIG. 4 illustrates the results of a verification experiment on the effectiveness of the birefringent principal axis direction. In the verification experiment shown in the same figure, the BSC
The measured value when the main axis direction of the SC is changed is compared with an ideal value. From this comparison result, as shown in FIG.
The measured value and the ideal value straight line of the birefringent principal axis direction in which the SC was changed almost coincided with each other, and it was confirmed that the measurement error was about ± 1.2 degrees (deg).
【００４７】図５は、有効な測定速度に関する検証実験
の結果を説明するものである。同図に示す検証実験は、
データ取り込み間隔を１ｍｓと一定にして、１００回の
測定を行うことにより、ロックインアンプ（ＬＩＡ）の
時定数と測定値のばらつきの関係を調べるものである。
この実験結果により、同図に示すように、有効な測定速
度が約１００μｓ以上であることが確認された。FIG. 5 illustrates the results of a verification experiment on the effective measurement speed. The verification experiment shown in FIG.
The relationship between the time constant of the lock-in amplifier (LIA) and the variation of the measured value is examined by performing the measurement 100 times while keeping the data acquisition interval constant at 1 ms.
The experimental results confirmed that the effective measurement speed was about 100 μs or more, as shown in FIG.
【００４８】以上により、本実施例に係る複屈折装置
は、偏光素子や試料を回転させる必要がない分、測定時
間の高速化（例えば、約１００μｓ）を図ることができ
ると共に、従来の装置に比べ光学系を簡素化したにもか
かわらず、高精度の複屈折位相差（例えば、最小検出限
界の平均値が約０．０５４度）及び複屈折主軸方位（例
えば、測定誤差が約±１．２度）を同時に測定できる。As described above, the birefringence device according to the present embodiment can speed up the measurement time (for example, about 100 μs) because there is no need to rotate the polarizing element or the sample, and can reduce the conventional device. Despite the simplification of the optical system, high-precision birefringence phase difference (for example, the average value of the minimum detection limit is about 0.054 degrees) and the birefringence principal axis direction (for example, a measurement error of about ± 1. 2) can be measured simultaneously.
【００４９】このように、高精度の複屈折測定を高速に
実行できる利点を生かして、時間的に変化する変動的な
複屈折の測定に関する実験を更に試みた。この実験に使
用した試料搭載装置を図６に示す。同図の如く、この試
料搭載装置は、アクリル試料に変動的な複屈折量を与え
るもので、アクリル試料の上部から変動的に等分布荷重
を加えるためのモータ及びコイルバネを備える。従っ
て、この試料搭載装置は、モータの回転に応じてコイル
バネが伸縮し、アクリル試料の上部から等分布荷重の負
荷及び除荷を繰り返すようになっている。Thus, taking advantage of the advantage that high-precision birefringence measurement can be performed at high speed, an experiment on measurement of time-varying and variable birefringence was further attempted. FIG. 6 shows the sample mounting device used in this experiment. As shown in the figure, the sample mounting apparatus gives a variable amount of birefringence to an acrylic sample, and includes a motor and a coil spring for applying a uniformly distributed load from above the acrylic sample. Therefore, in this sample mounting apparatus, the coil spring expands and contracts in accordance with the rotation of the motor, and the loading and unloading of the uniformly distributed load are repeated from above the acrylic sample.
【００５０】図７は、アクリル試料に加える荷重に対す
る複屈折位相差の応答に関する実験結果を説明するもの
である。同図に示す実験は、アクリル試料に加える荷重
を一定量毎に変化させたときの複屈折位相差の応答を測
定するものである。この測定結果により、同図に示すご
とく、一定の荷重変化に対し複屈折位相差がほぼ直線的
に変化していることが確認された。FIG. 7 illustrates the results of an experiment on the response of the birefringence phase difference to the load applied to the acrylic sample. The experiment shown in the figure is to measure the response of the birefringence phase difference when the load applied to the acrylic sample is changed for each fixed amount. From this measurement result, as shown in the figure, it was confirmed that the birefringence phase difference changed almost linearly with a constant load change.
【００５１】図８は、変動的な複屈折量を与えたときの
複屈折位相差の応答に関する実験結果を説明するもので
ある。この実験は、図６に示す試料搭載装置のモータを
回転させて、アクリル試料に変動的な複屈折量を与えた
ときの測定値を、図７の実験結果から得られた理想値と
比較したものである。この比較結果から、理想値及び測
定値の夫々の振幅及び周期がほぼ一致していることが確
認された。FIG. 8 is a graph for explaining the experimental results on the response of the birefringence phase difference when a variable amount of birefringence is given. In this experiment, the measured value when a variable amount of birefringence was given to the acrylic sample by rotating the motor of the sample mounting apparatus shown in FIG. 6 was compared with the ideal value obtained from the experimental result in FIG. Things. From this comparison result, it was confirmed that the respective amplitudes and periods of the ideal value and the measured value almost matched.
【００５２】以上により、本実施例に係る複屈折測定装
置は、特に時間的に変化する変動的な複屈折の測定にお
いて、上記高速化の効果を最大限に発揮できる。As described above, the birefringence measuring apparatus according to the present embodiment can maximize the effect of the above-mentioned speed-up in the measurement of the birefringence that changes with time, in particular.
【００５３】なお、本実施例に係る複屈折測定装置は、
光源にＳＴＺＬと４分の１波長板とを組み合わせた構成
としたが、本発明はこれに限定されるものではない。例
えば、軸ゼーマンレーザを単独に配置した光源でもよ
く、この場合は上記効果に加え、光源の構成を簡素に構
築できる利点もある。また、１つの周波数成分から成る
直線偏光レーザと偏光素子等を組み合わせた光源を適用
してもよい。要するに、光源は２周波円偏光を生成する
構成であればよい。The birefringence measuring device according to the present embodiment is
Although the configuration is such that the STZL and the quarter-wave plate are combined with the light source, the present invention is not limited to this. For example, a light source in which an axial Zeeman laser is independently arranged may be used. In this case, in addition to the above-described effects, there is an advantage that the configuration of the light source can be simply constructed. Further, a light source combining a linearly polarized laser composed of one frequency component and a polarizing element may be applied. In short, the light source only needs to be configured to generate two-frequency circularly polarized light.
【００５４】また、本実施例に係る複屈折測定装置は、
検出部（試料ステージ、光学系、光電検出器）を試料の
透過光を利用する共通光路上に設定したが、本発明はこ
れに限定されるものではない。例えば、検出部を試料の
反射光を利用する共通光路上に設定してもよい。また、
試料の透過光及び反射光の内の少なくとも一方を利用す
る構成であってもよい。Further, the birefringence measuring apparatus according to the present embodiment
Although the detection unit (sample stage, optical system, photoelectric detector) is set on a common optical path using transmitted light of the sample, the present invention is not limited to this. For example, the detection unit may be set on a common optical path using reflected light of the sample. Also,
A configuration using at least one of the transmitted light and the reflected light of the sample may be used.
【００５５】さらに、本実施例に係る複屈折測定装置
は、試料の複屈折位相差Δを上記（１０）で代表される
一般式で求めたが、特定の制約条件を満足する特定の試
料を測定対象とする場合においては近似式を用いて求め
てもよい。例えば、複屈折位相差Δが微小である、即ち
Δ＜＜１の条件を満たす試料を測定対象としたとき、複
屈折位相差Δを、Further, in the birefringence measuring apparatus according to the present embodiment, the birefringence phase difference Δ of the sample was obtained by the general formula represented by the above (10). In the case of a measurement target, it may be obtained using an approximate expression. For example, when the birefringence phase difference Δ is very small, that is, when a sample satisfying the condition of Δ << 1 is set as a measurement target, the birefringence phase difference Δ
【数１０】 の近似式で求めてもよい。(Equation 10) May be obtained by the approximate expression
【００５６】[0056]
【発明の効果】以上説明したように、請求項１〜１２記
載の発明に係る複屈折測定装置は、光源により２つの互
いに異なる周波数成分を有し且つその２つの周波数成分
が互いに反対向きの円偏光となるレーザ光を発振し、そ
のレーザ光の光信号を試料を介して検出し、その検出し
た光信号に基づいて試料の少なくとも複屈折位相差及び
複屈折主軸方位を同時に計測する構成としたため、装置
全体の構成を簡素に構築することができると共に、偏光
素子や試料を回転させる必要がない分、測定時間の高速
化を図ることができる。As described above, the birefringence measuring apparatus according to the first to twelfth aspects of the present invention has two different frequency components depending on the light source, and the two frequency components are opposite to each other. Oscillation of polarized laser light, detection of the optical signal of the laser light through the sample, and simultaneous measurement of at least the birefringence phase difference and the birefringent principal axis direction of the sample based on the detected optical signal. In addition, the configuration of the entire apparatus can be simply constructed, and the measurement time can be shortened because there is no need to rotate the polarizing element or the sample.
【図１】実施例に係る複屈折測定装置の全体構成を示す
概略ブロック図。FIG. 1 is a schematic block diagram showing the overall configuration of a birefringence measuring device according to an embodiment.
【図２】複屈折位相差の有効性に関する検証実験の結果
を説明する図。FIG. 2 is a diagram illustrating the results of a verification experiment regarding the effectiveness of birefringence phase difference.
【図３】複屈折位相差の最小検出限界に関する検証実験
の結果を説明する図。FIG. 3 is a view for explaining results of a verification experiment on a minimum detection limit of a birefringence phase difference.
【図４】複屈折主軸方位の有効性に関する検証実験の結
果を説明する図。FIG. 4 is a diagram illustrating the results of a verification experiment regarding the effectiveness of the birefringent principal axis direction.
【図５】有効な測定速度に関する検証実験の結果を説明
する図。FIG. 5 is a view for explaining the result of a verification experiment regarding an effective measurement speed.
【図６】変動的複屈折測定に使用した試料搭載装置の概
要図。FIG. 6 is a schematic diagram of a sample mounting device used for a variable birefringence measurement.
【図７】荷重に対する複屈折位相差の応答に関する実験
結果を説明する図。FIG. 7 is a view for explaining an experimental result regarding a response of a birefringent phase difference to a load.
【図８】変動的複屈折量に対する複屈折位相差の応答に
関する実験結果を説明する図。FIG. 8 is a view for explaining an experimental result regarding a response of a birefringence phase difference to a variable birefringence amount.
１ 光源 ２ 検出測定部 ３ 検出部（本発明の検出手段を成す） ４ 計測部（本発明の計測手段を成す） ５ 試料ステージ Ｓａ 試料 ６ 光学系 ６ａ ４分の１波長板 ６ｂ 直線偏光子 ７ 光電検出器 ８ ロックインアンプ ９ ローパスフィルタ １０ 演算部 １１ ＣＰＵ（演算器） １２ 出力デバイス Reference Signs List 1 light source 2 detection / measurement unit 3 detection unit (constituting detection means of the present invention) 4 measuring unit (constituting measurement means of the present invention) 5 sample stage Sa sample 6 optical system 6a quarter-wave plate 6b linear polarizer 7 Photoelectric detector 8 lock-in amplifier 9 low-pass filter 10 operation unit 11 CPU (operation unit) 12 output device
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平５−249031（ＪＰ，Ａ) 特開 平５−45278（ＪＰ，Ａ) 特開 平８−128946（ＪＰ，Ａ) 特公 昭59−50927（ＪＰ，Ｂ２) 特公 平６−12333（ＪＰ，Ｂ２) (58)調査した分野(Int.Cl.6，ＤＢ名) G01N 21/23 G01N 21/21 G01N 21/19──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-249031 (JP, A) JP-A-5-45278 (JP, A) JP-A-8-128946 (JP, A) 50927 (JP, B2) JP 6-12333 (JP, B2) (58) Fields investigated (Int. Cl. 6 , DB name) G01N 21/23 G01N 21/21 G01N 21/19
Claims (12)
状態に関する情報を測定する複屈折測定装置において、
２つの互いに異なる周波数成分を有し且つその２つの周
波数成分が互いに反対向きの円偏光となるレーザ光を発
振する光源と、この光源による当該レーザ光を上記試料
に向けて発振させることにより当該試料の上記複屈折状
態を反映したレーザ光の光信号を検出する検出手段と、
この検出手段により検出された当該光信号に基づいて上
記試料の少なくとも複屈折位相差及び複屈折主軸方位を
同時に計測する計測手段とを備えたことを特徴とする複
屈折測定装置。1. A birefringence measuring apparatus for measuring information on a birefringence state of a sample to be measured by laser light,
A light source that oscillates a laser beam having two different frequency components and the two frequency components are circularly polarized in opposite directions, and oscillating the laser beam by the light source toward the sample to produce the sample. Detecting means for detecting an optical signal of laser light reflecting the birefringence state of the above,
A birefringence measuring device comprising: a measuring means for simultaneously measuring at least a birefringence phase difference and a birefringent principal axis direction of the sample based on the optical signal detected by the detecting means.
成分を有し且つその２つの周波数成分が互いに直交した
直線偏光となるレーザ光を発振するレーザと４分の１波
長板とを組み合わせて成る請求項１記載の複屈折測定装
置。2. The light source according to claim 1, wherein the light source has a laser that oscillates a laser beam having two different frequency components, and the two frequency components become linearly polarized light orthogonal to each other, and a quarter-wave plate. The birefringence measurement device according to claim 1.
レーザである請求項２記載の複屈折測定装置。3. The birefringence measurement apparatus according to claim 2, wherein the laser is a frequency stabilized transverse Zeeman laser.
れた上記レーザ光の当該２つの周波数成分を前記試料を
介して光学的に相互に干渉させる光学系と、この光学系
からの干渉後の光ビート成分を含むレーザ光の光信号を
電気信号に変換して検出する光電検出器とを備えた請求
項１又は２記載の複屈折測定装置。4. An optical system for optically interfering the two frequency components of the laser light oscillated by the light source with each other through the sample, and a detector after interference from the optical system. 3. The birefringence measuring apparatus according to claim 1, further comprising: a photoelectric detector that converts an optical signal of a laser beam including an optical beat component into an electrical signal and detects the electrical signal.
レーザ光の２つの周波数成分の夫々における偏光状態の
位相を９０度変換する４分の１波長板と、この４分の１
波長板を介して入射されるレーザ光の上記２つの周波数
成分を相互に干渉させ且つその干渉させて得られる光ビ
ート成分を含むレーザ光を出射する直線偏光子とを備
え、上記光源及び４分の１波長板間の光路上に前記試料
を配置するように形成した請求項４記載の複屈折測定装
置。5. The quarter wavelength plate for converting the phase of the polarization state of each of the two frequency components of the laser beam incident from the light source by 90 degrees, and the quarter wavelength plate.
A linear polarizer that causes the two frequency components of the laser light incident through the wavelength plate to interfere with each other and emits a laser light including an optical beat component obtained by the interference; 5. The birefringence measuring apparatus according to claim 4, wherein the sample is formed on the optical path between the one wavelength plates.
軸に直交する面内の光軸を中心として予め設定された基
準方位に対して進相軸方位が４５度となる位置に配置す
る一方、前記直線偏光子を上記基準方位に対して偏光透
過軸方位が０度となる位置に配置した請求項５記載の複
屈折測定装置。6. The quarter-wave plate is positioned at a position where the fast axis direction is 45 degrees with respect to a preset reference direction around an optical axis in a plane orthogonal to the optical axis of the laser light. 6. The birefringence measurement device according to claim 5, wherein the linear polarizer is disposed at a position where the polarization transmission axis direction is 0 degree with respect to the reference direction.
る請求項４記載の複屈折測定装置。7. The birefringence measuring device according to claim 4, wherein said photoelectric detector is a photodiode.
した電気信号から直流成分を抽出するローパスフィルタ
と、上記光電検出器が検出した電気信号から前記光ビー
ト成分に相当する交流成分を抽出するロックインアンプ
と、上記ローパスフィルタにより抽出された直流成分及
び上記ロックインアンプにより抽出された交流成分に基
づいて前記試料の複屈折位相差及び複屈折主軸方位を同
時に演算する演算部とを備えた請求項４記載の複屈折測
定装置。8. A low-pass filter for extracting a DC component from an electric signal detected by the photoelectric detector, and an AC component corresponding to the optical beat component from the electric signal detected by the photoelectric detector. A lock-in amplifier, and a calculation unit for simultaneously calculating the birefringence phase difference and the birefringence principal axis direction of the sample based on the DC component extracted by the low-pass filter and the AC component extracted by the lock-in amplifier. The birefringence measurement device according to claim 4.
２つの直交成分をＩｘ及びＩｙとし、前記直流成分をＩ
DCとし、前記試料の複屈折位相差をΔとし、その複屈折
主軸方位をψとしたとき、この複屈折位相差Δ及び複屈
折主軸方位ψを、 【数１】 の計算式で演算するアルゴリズムを実行するように設定
された演算器を備えた請求項８記載の複屈折測定装置。9. The arithmetic unit defines two orthogonal components corresponding to the AC component as Ix and Iy, and defines the DC component as Ix
DC , the birefringence phase difference of the sample is Δ, and the birefringence principal axis direction is ψ, the birefringence phase difference Δ and the birefringence principal axis direction ψ are given by 9. The birefringence measuring apparatus according to claim 8, further comprising an arithmetic unit set to execute an algorithm for calculating the birefringence by the following equation.
記試料の複屈折位相差及び複屈折主軸方位を出力する出
力デバイスを、前記計測手段が更に備えた請求項８記載
の複屈折測定装置。10. The birefringence measurement apparatus according to claim 8, wherein the measurement unit further includes an output device that outputs a birefringence phase difference and a birefringence principal axis direction of the sample calculated simultaneously by the calculation unit.
折状態に関する情報を測定する複屈折測定装置におい
て、２つの互いに異なる周波数成分を有し且つその２つ
の周波数成分が互いに反対向きの円偏光となるレーザ光
を発振する光源と、この光源から上記試料を介して入射
されたレーザ光の２つの周波数成分の夫々における偏光
状態の位相を９０度変換する４分の１波長板と、この４
分の１波長板を介して入射されたレーザ光の上記２つの
周波数成分を相互に干渉させ且つその干渉させて得られ
る光ビート成分を含むレーザ光を出射する直線偏光子
と、この直線偏光子を介して入射されたレーザ光の光信
号を電気信号に変換して検出する光電検出器と、この光
電検出器が検出した電気信号から直流成分を抽出するロ
ーパスフィルタと、上記光電検出器が検出した電気信号
から上記光ビート成分に相当する交流成分を抽出するロ
ックインアンプと、上記ローパスフィルタにより抽出さ
れた直流成分及び上記ロックインアンプにより抽出され
た交流成分に基づいて上記試料の複屈折位相差及び複屈
折主軸方位を同時に演算する演算部とを備えると共に、
上記演算部は、上記直流成分をＩDCとし、上記交流成分
に相当する２つの直交成分をＩｘ及びＩｙとし、上記試
料の複屈折位相差をΔとし、その複屈折主軸方位をψと
したとき、その複屈折位相差Δ及び複屈折主軸方位ψ
を、 【数２】 の計算式で演算するように設定されたことを特徴とする
複屈折測定装置。11. A birefringence measuring apparatus for measuring information on a birefringence state of a sample to be measured by a laser beam, wherein the birefringence measuring apparatus has two mutually different frequency components, and the two frequency components are circularly polarized light having opposite directions. A light source that oscillates the laser light, a quarter-wave plate that converts the phase of the polarization state of each of the two frequency components of the laser light incident from the light source through the sample by 90 degrees,
A linear polarizer for causing the two frequency components of the laser beam incident via the half-wave plate to interfere with each other and emitting a laser beam containing an optical beat component obtained by the interference; A photoelectric detector that converts an optical signal of a laser beam incident through the optical signal into an electric signal and detects the electric signal; a low-pass filter that extracts a DC component from the electric signal detected by the photoelectric detector; A lock-in amplifier for extracting an AC component corresponding to the optical beat component from the obtained electric signal, and a birefringence position of the sample based on the DC component extracted by the low-pass filter and the AC component extracted by the lock-in amplifier. A computing unit that simultaneously computes the phase difference and the birefringence principal axis direction is provided,
The arithmetic unit calculates the DC component as I DC , the two orthogonal components corresponding to the AC component as Ix and Iy, the birefringence phase difference of the sample as Δ, and the birefringence principal axis direction as ψ. , Its birefringent phase difference Δ and birefringent principal axis direction ψ
Is given by A birefringence measurement device set to be calculated by the following formula:
請求項１記載の複屈折測定装置。12. The birefringence measurement apparatus according to claim 1, wherein the light source comprises an axial Zeeman laser.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5904895A JP2828604B2 (en) | 1995-03-17 | 1995-03-17 | Birefringence measurement device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5904895A JP2828604B2 (en) | 1995-03-17 | 1995-03-17 | Birefringence measurement device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08254495A JPH08254495A (en) | 1996-10-01 |
| JP2828604B2 true JP2828604B2 (en) | 1998-11-25 |
Family
ID=13102052
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5904895A Expired - Fee Related JP2828604B2 (en) | 1995-03-17 | 1995-03-17 | Birefringence measurement device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2828604B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3679774B2 (en) | 2002-03-29 | 2005-08-03 | キヤノン株式会社 | Birefringence measuring apparatus and method |
| JP5375213B2 (en) * | 2009-03-06 | 2013-12-25 | 旭硝子株式会社 | Manufacturing method of glass substrate for display and manufacturing method of flat panel display |
| JP2010009061A (en) * | 2009-10-06 | 2010-01-14 | Asahi Glass Co Ltd | Method of manufacturing glass substrate for display |
| JP5434977B2 (en) * | 2011-07-11 | 2014-03-05 | 旭硝子株式会社 | Manufacturing method of glass substrate for display and manufacturing method of flat panel display |
-
1995
- 1995-03-17 JP JP5904895A patent/JP2828604B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08254495A (en) | 1996-10-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5663793A (en) | Homodyne interferometric receiver and calibration method having improved accuracy and functionality | |
| JP6077050B2 (en) | Atomic sensor system | |
| Yu et al. | Development of a compact, fiber-coupled, six degree-of-freedom measurement system for precision linear stage metrology | |
| JP2010038906A (en) | Bias-instability reduction in fiber optic gyroscope | |
| US6473181B1 (en) | Measurement of waveplate retardation using a photoelastic modulator | |
| Liu et al. | Method for the measurement of phase retardation of any wave plate with high precision | |
| JP2007057324A (en) | Fiber optic measuring system | |
| US6563593B2 (en) | Dynamic angle measuring interferometer | |
| CN115727829A (en) | Control method and system for inhibiting influence of alkali metal polarization magnetic field | |
| JPH0781915B2 (en) | Method and apparatus for real-time measurement of the polarization state of quasi-monochromatic rays | |
| US5517022A (en) | Apparatus for measuring an ambient isotropic parameter applied to a highly birefringent sensing fiber using interference pattern detection | |
| JP2828604B2 (en) | Birefringence measurement device | |
| JP2903486B2 (en) | Dispersion interferometer | |
| Wang et al. | Two-dimensional straightness measurement based on optical knife-edge sensing | |
| Martinelli | The dynamical behavior of a single-mode optical fiber strain gage | |
| US6011402A (en) | Electro-optic apparatus and method for measuring electric-field vector | |
| Chen et al. | Alternative method for measuring the phase retardation and fast axis of a wave plate | |
| Lee et al. | A compact circular heterodyne interferometer for simultaneous measurements of variation in the magnitude of phase retardation and principal axis angle | |
| Umeda et al. | Measurement of the residual birefringence distribution in glass laser disk by transverse zeeman laser | |
| JPH11351814A (en) | Stabilized interference measuring instrument | |
| JP6989852B2 (en) | Electric field sensor | |
| Gao et al. | A 5MHz beat frequency He–Ne laser equipped with bireflectance cavity mirror | |
| JP2713190B2 (en) | Optical property measuring device | |
| Liu et al. | Differential variation of laser longitudinal mode spacing induced by small intra-cavity phase anisotropies | |
| JPH08304084A (en) | Optical fiber gyro |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20070918 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Year of fee payment: 10 Free format text: PAYMENT UNTIL: 20080918 |
|
| LAPS | Cancellation because of no payment of annual fees |