JPH0612333B2 - Automatic birefringence measuring device - Google Patents
Automatic birefringence measuring deviceInfo
- Publication number
- JPH0612333B2 JPH0612333B2 JP23721288A JP23721288A JPH0612333B2 JP H0612333 B2 JPH0612333 B2 JP H0612333B2 JP 23721288 A JP23721288 A JP 23721288A JP 23721288 A JP23721288 A JP 23721288A JP H0612333 B2 JPH0612333 B2 JP H0612333B2
- Authority
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- Prior art keywords
- wave plate
- light source
- laser light
- rotation
- frequency
- Prior art date
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
- G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
- G01M11/331—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face by using interferometer
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- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Testing Of Optical Devices Or Fibers (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、光ディスクメモリ基板、レンズ、液晶用ガラ
ス基板、光学結晶等に残留する光学的歪による複屈折量
とその進相軸方位を精度よく自動的に測定することがで
きる自動複屈折測定装置に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention accurately determines the amount of birefringence due to optical strain remaining in an optical disk memory substrate, lens, glass substrate for liquid crystal, optical crystal, etc. and its fast axis azimuth. The present invention relates to an automatic birefringence measuring device that can measure automatically well.
（従来の技術） ２つの周波数からなりその偏光状態が互いに直角に交わ
る直線偏光からなる光（例えばゼーマンレーザ）を用い
て透明物体の光学的歪による複屈折量を、その光の周波
数差ビート信号の位相変化から測定する方法（例えば特
公昭５９−５０９２７号公報）が開発されている。(Prior Art) The amount of birefringence due to optical distortion of a transparent object is measured by using light (for example, Zeeman laser) that is linearly polarized light having two frequencies and whose polarization states intersect each other at right angles. Has been developed (for example, Japanese Examined Patent Publication No. 59-50927).
この方法を、実施するための基本的な構成を示す第３図
を参照して簡単に説明する。This method will be briefly described with reference to FIG. 3 showing a basic configuration for carrying out the method.
光源Ｌは、２つの直線偏光方位が紙面に垂直なｘ方向と
紙面内のｙ方向に平行で、かつ、発振光周波数が互いに
数百ＫＨｚだけ異なる光を同時に発振している。The light source L simultaneously oscillates light in which two linear polarization directions are parallel to the x direction perpendicular to the paper surface and the y direction in the paper surface and the oscillating light frequencies differ from each other by several hundred KHz.
光源Ｌからの光は、半透鏡ＨＭを介して複屈折量を測り
たい透光性の測定試料Ｓを通過し、方向がｘ方向から４
５゜傾いた直線偏光子ＬＰ１に入射させられる。The light from the light source L passes through the semitransparent mirror HM, the transparent sample S for measuring the birefringence amount, and the direction from the x direction is 4
It is incident on the linear polarizer LP 1 tilted by 5 °.
ただし、複屈折性をもつ測定試料Ｓの主軸方位はｘ方
向、もしくはｙ方向に一致しているものとする。However, it is assumed that the principal axis azimuth of the measurement sample S having birefringence matches the x direction or the y direction.
このとき光源Ｌの光が測定試料Ｓを通過する前後で複屈
折性をもつその測定試料の複屈折量によってその光の位
相遅れに違いが生じる。At this time, before and after the light from the light source L passes through the measurement sample S, the phase delay of the light varies depending on the birefringence amount of the measurement sample having the birefringence.
そこで、直線偏光子ＬＰ１を用いてｘ，ｙ成分を干渉さ
せ、２つの成分の差周波ビートを光電検出器ＰＨ１で検
出すると、その交流信号の位相成分は測定試料Ｓ複屈折
量に比例する。Therefore, when the x and y components are caused to interfere with each other by using the linear polarizer LP 1 and the difference frequency beat of the two components is detected by the photoelectric detector PH 1 , the phase component of the AC signal is proportional to the birefringence amount of the measurement sample S. To do.
レーザ光束が測定試料Ｓに入射する前にその一部を半透
鏡ＨＭで抜き出し、４５゜直線偏光子ＬＰ２で２成分を
干渉させ光電検出器ＰＨ２によって得られたビート信号
を参照信号として、前述の測定信号と電気位相計で位相
差を測定することによって複屈折量が求められる。Before the laser beam is incident on the measurement sample S, a part thereof is extracted by the semi-transparent mirror HM, the two components are interfered by the 45 ° linear polarizer LP 2 , and the beat signal obtained by the photoelectric detector PH 2 is used as a reference signal. The birefringence amount is obtained by measuring the phase difference with the above-mentioned measurement signal and an electric phase meter.
これを数式で示すと以下のようになる。This can be expressed by the following formula.
測定試料Ｓに入射する前のｘ，ｙ方向の電界成分Ｅｘ，
Ｅｙは、 Ｅｘ＝ａｘcosωｘｔ Ｅｙ＝ａｙcosωｙｔ ・・・(1) と書ける。The electric field component E x in the x and y directions before entering the measurement sample S,
E y is, E x = a x cosω x t E y = a y cosω y t ··· (1) and write.
ここで、ａｘ，ａｙは振幅，ωｘ，ωｙは角周波数であ
る。Here, a x and a y are amplitudes, and ω x and ω y are angular frequencies.
透光性物体の厚みをｄ，ｘ方向に屈折率をｎｘ，ｙ方向
の屈折率をｎｙ，波数をｋとすると透光性物体を通過し
た光の電界成分Ｅｘ，Ｅｙは次のように変化する。When the thickness of the transparent object is d, the refractive index in the x direction is n x , the refractive index in the y direction is n y , and the wave number is k, the electric field components E x and E y of the light passing through the transparent object are It changes like.
Ｅｘ＝ａｘcos（ωｘｔ＋ｋｄｎｘ） Ｅｙ＝ａｙcos（ωｙｔ＋ｋｄｎｙ）・・・(2) (2)式の光を４５゜方位の直線偏光子を通して干渉さ
せ、それを光電検出すると得られる光電流は次式のよう
になる。E x = a x cos (ω x t + kdn x ) E y = a y cos (ω y t + kdn y ) ... The photocurrent obtained by photoelectric detection is as follows.
Ｉ＝〔ａｘ ２＋ａｙ ２＋２ａｘａｙcos｛ωｂｔ＋ｋｄ
（ｎｘ−ｎｙ）｝〕／２ ・・・(3) ここで、ωｂ＝ωｘ−ωｙとなって２つの偏光成分の周
波数差である。I = [a x 2 + a y 2 + 2a x a y cos {ω b t + kd
(N x -n y)}] / 2 (3) where is the frequency difference between the two polarization components becomes ω b = ω x -ω y.
一方(1)式の光も、同様に４５゜方位直線偏光子を用い
て干渉させて、光電流を検出する。On the other hand, the light of the formula (1) is similarly interfered by using a 45 ° azimuth linear polarizer to detect the photocurrent.
Ｉref＝（ａｘ ２＋ａｙ ２＋２ａｘａｙcosωｂｔ）／２
・・・(4) (3)、(4)式は、２つの成分の差周波ビートを表してお
り、ωｂは、数百ＫＨｚであるから通常の電気位相計を
用いて２つの交流信号の位相差δを求めることができ
る。 Iref = (a x 2 + a y 2 + 2a x a y cosω b t) / 2
・ ・ ・ (4) Equations (3) and (4) represent the difference frequency beat of two components, and ω b is several hundred KHz, so two AC signals are output using an ordinary electric phase meter. Can be obtained.
その結果(3)、(4)式よりδは、λを平均波長として次の
ようになる。As a result, from equations (3) and (4), δ is as follows, where λ is the average wavelength.
δ＝ｄ（ｎｘ−ｎｙ）２π／λ・・・・・(5) すなわち位相計の出力は、透光性物体の複屈折量ｎｘ−
ｎｙに比例することがわかる。δ = d (n x −n y ) 2π / λ (5) That is, the output of the phase meter is the birefringence amount n x − of the translucent object.
it can be seen that the proportion to n y.
（発明が解決しようとする課題） 以上のように２周波直交偏光光を用いて透光性の測定対
象の複屈折量を交流信号の位相差から精度よく測定でき
ることがわかった。しかしこの従来の測定法に以下には
述べる問題点がある。(Problems to be Solved by the Invention) As described above, it has been found that the birefringence amount of the translucent measurement target can be accurately measured from the phase difference of the AC signal by using the dual-frequency orthogonally polarized light. However, this conventional measuring method has the following problems.
(4)式を求める過程において、測定対象の複屈折の進相
軸方位は既知であり、２周波直交偏光光源の直線偏光方
位の１つに平行であると仮定した。In the process of obtaining the equation (4), it was assumed that the fast axis direction of the birefringence to be measured was known and was parallel to one of the linear polarization directions of the dual frequency orthogonal polarization light source.
しかし、実際の透光性の測定対象、たとえばレンズや液
晶ガラス基板の歪により生じる複屈折の主軸方向は不明
である。However, the actual measurement target of translucency, for example, the principal axis direction of birefringence caused by distortion of a lens or a liquid crystal glass substrate is unknown.
もし光源の直線偏光方位と測定対象の複屈折主軸方位が
一致しない場合、真の複屈折量より小さな値となって測
定誤差を生じる 本発明の目的は、測定対象の複屈折の進相軸方位が不明
であっても、その複屈折量と進相軸方位を精度よく自動
的に測定することができる自動複屈折測定装置を提供す
ることにある。If the linear polarization azimuth of the light source and the birefringence principal axis azimuth of the measurement target do not match, the value becomes smaller than the true birefringence amount and a measurement error occurs. It is an object of the present invention to provide an automatic birefringence measuring apparatus capable of accurately and automatically measuring the birefringence amount and the fast axis azimuth even if the value is unknown.
（課題を解決するための手段） 前期目的を達成するため、本発明による自動複屈折測定
装置は、周波数差をもつ２つの直交した偏光成分から成
る２周波直交偏光レーザ光源と、前記レーザ光源の光軸
上に対向して配置されている光電検出器と、前記レーザ
光源と光電検出器を結ぶ光路中に光軸の周りに回転可能
に配置されている２分の１波長板と、前記光路中に前記
２分の１波長板に続いて配置され光軸の周りに回転可能
に配置される直線偏光子と、前記２分の１波長板と直線
偏光子との間に設けられている複屈折測定試料配置部
と、前記２分の１波長板の回転に対して前記直線偏光子
の回転が２倍になるように同期させて駆動する駆動手段
と、前記２分の１波長板が１回転した時光電検出器によ
って得られる検出出力より進相軸方位または複屈折量を
測定する演算装置から構成されている。(Means for Solving the Problem) In order to achieve the object of the first aspect, an automatic birefringence measuring apparatus according to the present invention comprises a dual-frequency orthogonal polarization laser light source composed of two orthogonal polarization components having a frequency difference, and the laser light source. A photoelectric detector arranged to face the optical axis, a half-wave plate rotatably arranged around the optical axis in an optical path connecting the laser light source and the photoelectric detector, and the optical path. A linear polarizer disposed inside the half-wave plate and rotatably around the optical axis, and a multi-layer polarizer provided between the half-wave plate and the linear polarizer. The refraction measurement sample placement portion, a driving unit that drives the linear polarizer in synchronization so that the rotation of the half-wave plate is doubled with respect to the rotation of the half-wave plate, and the half-wave plate is one. When rotated, the fast axis direction or the detection output obtained by the photoelectric detector It is composed of an arithmetic unit for measuring the amount of birefringence.
また、本発明によるさらに他の自動複屈折測定装置は、
前記演算装置を前記２分の１波長板の回転周波数の４倍
の交流信号を参照信号とするロックインアンプにより得
られる信号から複屈折測定試料の進相軸方位または複屈
折量を測定するように構成してある。Still another automatic birefringence measuring device according to the present invention is
In order to measure the fast axis direction or the amount of birefringence of the birefringence measurement sample from the signal obtained by the lock-in amplifier, in which the arithmetic unit uses the AC signal of four times the rotation frequency of the half-wave plate as a reference signal. Is configured.
（実施例） 以下、図面等を参照して、本発明をさらに詳しく説明す
る。(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings.
第１図は、本発明による自動複屈折測定装置の実施例を
示すブロック図である。FIG. 1 is a block diagram showing an embodiment of an automatic birefringence measuring device according to the present invention.
レーザ光源Ｌは、互いに偏光方位が直交した２つのの直
線偏光を同時に発振している。それらの間に数百ＫＨｚ
の周波数差がある２つの成分を同時に発振している。The laser light source L simultaneously oscillates two linearly polarized lights whose polarization directions are orthogonal to each other. Between them hundreds of KHz
It oscillates two components with a frequency difference of.
前記レーザ光源Ｌからの光はその光軸を中心に、駆動手
段のステッピングモータＳＭ１によって回転させられる
２分の１波長板ＨＷＰを透過して測定試料Ｓに投射され
る。The light from the laser light source L is projected on the measurement sample S through the half-wave plate HWP rotated by the stepping motor SM 1 of the driving means about the optical axis thereof.
測定試料Ｓからの出射光は、光軸の周りに前記２分の１
波長板ＨＷＰの２倍の速度で駆動手段のステッピングモ
ータＳＭ２によって回転させられる直線偏光子ＬＰ１を
通って、光電検出器ＰＨ１に入射させられる。The light emitted from the measurement sample S is halved around the optical axis.
The light is incident on the photoelectric detector PH 1 through a linear polarizer LP 1 rotated by a stepping motor SM 2 of a driving unit at a speed twice that of the wave plate HWP.
駆動手段のステッピングモータＳＭ１，ＳＭ２を駆動す
るステッピングモータ駆動回転ＳＤ１，ＳＤ２には、演
算処理装置のＣＰＵから時計信号が供給されている。A clock signal is supplied from the CPU of the arithmetic processing unit to the stepping motor drive rotations SD 1 and SD 2 that drive the stepping motors SM 1 and SM 2 of the driving means.
光電検出器ＰＨ１は、数百ＫＨｚの強度変化に応答して
レーザ光の２成分の差周波ビート信号を測定信号として
出力する。The photoelectric detector PH 1 outputs the difference frequency beat signal of the two components of the laser light as a measurement signal in response to the intensity change of several hundred KHz.
一方、前記レーザ光源Ｌからのレーザ光が前記２分の１
波長板ＨＷＰに入射する前に一部が半透鏡ＨＭで抜き出
され、４５゜直線偏光子ＬＰ２を通して光電検出器ＰＨ
２で検出される。On the other hand, the laser light from the laser light source L is halved.
A part of the light is extracted by the semi-transparent mirror HM before entering the wave plate HWP, and the photoelectric detector PH is passed through the 45 ° linear polarizer LP 2.
Detected in 2 .
この検出されたビート信号は演算処理装置で参照信号と
して用いられる。The detected beat signal is used as a reference signal in the arithmetic processing unit.
演算処理装置の位相計ＰＭには前記測定信号と参照信号
が接続されその位相差が測定され、その出力電圧はアナ
ログ−ディジタル変換器ＡＤＣによってディジタル量に
変換される。The measurement signal and the reference signal are connected to the phase meter PM of the arithmetic processing unit, the phase difference between them is measured, and the output voltage thereof is converted into a digital quantity by the analog-digital converter ADC.
そして、そのデータが中央処理装置ＣＰＵに取り込まれ
処理され出力装置に出力される。Then, the data is taken into the central processing unit CPU, processed, and output to the output device.
第１図において、光源Ｌを出射した２周波直交直線偏光
成分からなるレーザ光束は紙面内の成分をｘ成分、垂直
方向をｙ成分とする。In FIG. 1, a laser light flux emitted from a light source L and composed of two-frequency orthogonal linearly polarized light components has an in-plane component as an x component and a vertical direction as a y component.
半透鏡ＨＭでその一部が反射され、その反射光は４５゜
直線偏光子ＬＰ２を通して干渉され、２成分の周波数差
が光電検出器ＰＨ２光ビート信号として検出される。こ
の直交信号を測定系の参照信号とする。A part of the light is reflected by the semi-transparent mirror HM, the reflected light is interfered through the 45 ° linear polarizer LP 2 , and the frequency difference between the two components is detected as a photodetector PH 2 optical beat signal. This orthogonal signal is used as a reference signal for the measurement system.
半透鏡ＨＭを透過した光束はステッピングモータＳＭ１
によって回転させられる２分の１波長板ＨＷＰを通る。The luminous flux transmitted through the semi-transparent mirror HM is a stepping motor SM 1
Through a half wave plate HWP which is rotated by.
２分の１波長板ＨＷＰは、その進相軸を基準としてその
相対方位角の２倍だけ入射直線偏光方位を回転させる機
構を持っている。The half-wave plate HWP has a mechanism for rotating the incident linear polarization azimuth by twice the relative azimuth angle with respect to the fast axis thereof.
例えば、水平直線偏光を、進相軸方位が２０゜である２
分の１波長板に入射すると、その出射光の直線偏光方位
は４０゜となる。For example, if the horizontal linearly polarized light has a fast axis azimuth of 20 °,
When the light is incident on the half-wave plate, the linear polarization azimuth of the emitted light is 40 °.
したがって、第１図の２分の１波長板ＨＷＰを出射した
光の偏光方位は、２分の１波長板ＨＷＰが３６０゜回転
すると、７２０゜だけ回転することになる。Therefore, the polarization azimuth of the light emitted from the half-wave plate HWP of FIG. 1 rotates by 720 ° when the half-wave plate HWP rotates 360 °.
そこで、複屈折の進相軸が任意の角度である測定試料Ｓ
に入射すると、入射光の２つの成分のうちより高い周波
数成分の偏光方位と進相軸方位が一致したとき、測定試
料を出射後の２成分の相対リターデーションは正に最大
になり、逆に低い周波数成分の偏光方位と進相軸方位が
一致したとき、負に最大となる。Therefore, the measurement sample S in which the fast axis of birefringence is at an arbitrary angle
When the polarization direction of the higher frequency component of the two components of the incident light coincides with the fast axis direction, the relative retardation of the two components after exiting the measurement sample is positively maximized, and conversely. When the polarization azimuth of the low frequency component and the fast axis azimuth coincide, the maximum is negative.
ところで、偏光方位の０゜と１８０゜は同じ方位角を表
しており、また、２分の１波長板ＨＷＰが３６０゜回転
するとその出射光の偏光方位は７２０゜回転するから、
上記の相対リターデーションは２分の１波長板ＨＷＰ１
回転に対し、４周期の正弦的変化を繰り返すことにな
る。By the way, the polarization azimuths 0 ° and 180 ° represent the same azimuth, and when the half-wave plate HWP rotates 360 °, the polarization azimuth of the emitted light rotates 720 °.
The above relative retardation is the half wave plate HWP1.
For rotation, four cycles of sinusoidal changes are repeated.
測定試料Ｓの相対リターデーションは、２周波直交偏光
成分間のビートの位相差から検出する。このとき、測定
試料Ｓの出射光の偏光方位は回転しているので、２成分
のビートを検出するため、初期方位角が２分の１波長板
ＨＷＰの進相軸方位に対し４５゜である直線偏光子ＬＰ
１を２分の１波長板ＨＷＰの倍の角度で同期しながら回
転させる。The relative retardation of the measurement sample S is detected from the phase difference of beats between the two-frequency orthogonal polarization components. At this time, since the polarization azimuth of the emitted light of the measurement sample S is rotating, the initial azimuth angle is 45 ° with respect to the fast axis azimuth of the half-wave plate HWP in order to detect the two-component beat. Linear polarizer LP
1 is rotated synchronously at an angle twice that of the half-wave plate HWP.
以上の測定によって２成分位相差の正弦的変化の振幅が
複屈折量、また、２分の１波長板ＨＷＰを０゜方位から
回転させて最初に位相差が最大になったときの２分の１
波長板ＨＷＰの方位の２倍の角度が複屈折の進相軸方位
である。According to the above measurement, the amplitude of the sinusoidal change of the two-component phase difference is the birefringence amount, and the half-wave plate HWP is rotated from the 0 ° azimuth direction and the phase difference becomes the half-maximum first. 1
An angle twice the azimuth of the wave plate HWP is the fast axis azimuth of the birefringence.
本発明による装置ではこれを自動式に測定する。そのた
めに、演算処理装置のＣＰＵからの時計信号により駆動
手段を動作させ、２分の１波長板ＨＷＰと直線偏光子Ｌ
Ｐ１の回転を制御する。The device according to the invention measures this automatically. Therefore, the driving means is operated by the clock signal from the CPU of the arithmetic processing unit, and the half-wave plate HWP and the linear polarizer L are operated.
Control the rotation of P 1 .
２分の１波長板ＨＷＰ１回転に対して位相計ＰＭの出力
電圧をアナログ−ディジタル変換器ＡＤＣを通して演算
処理装置に取り込む。そして、フーリエ変換器ＦＦＴに
よって４周期成分の振幅と初期位相を計算することによ
り測定試料Ｓの複屈折量とその進相方位が自動的に求め
られ、出力装置に出力される。The output voltage of the phase meter PM is taken into the arithmetic processing unit through the analog-digital converter ADC for one rotation of the half-wave plate HWP. Then, the Fourier transformer FFT calculates the amplitude and initial phase of the 4-period component, so that the birefringence amount of the measurement sample S and its phase advance direction are automatically obtained and output to the output device.
第２図は本発明による他の自動複屈折測定装置の実施例
を示すブロック図である。FIG. 2 is a block diagram showing an embodiment of another automatic birefringence measuring device according to the present invention.
レーザ光束が２分の１波長板ＨＷＰ，測定試料Ｓ，直線
偏光子ＬＰ１を通過して、光検出器ＰＨ１によって検出
され、演算処理装置の前述と同様に光検出器ＰＨ２が参
照信号として接続されている位相計ＰＭに入力される。The laser light flux passes through the half-wave plate HWP, the measurement sample S, and the linear polarizer LP 1 and is detected by the photodetector PH 1 , and the photodetector PH 2 outputs the reference signal as in the above description of the arithmetic processing device. Is input to the phase meter PM connected as.
この基本的な光学系は、第１図と変わらないが駆動手段
と演算処理装置の構成が異なっている。Although this basic optical system is the same as that shown in FIG. 1, the drive means and the arithmetic processing unit are different in configuration.
検出器ＰＨ１によって検出された２成分の光ビート交流
信号は、演算処理装置のロックインアンプＬＡで同期検
出法によって検出される。The two-component optical beat AC signal detected by the detector PH 1 is detected by the lock-in amplifier LA of the arithmetic processing device by the synchronous detection method.
駆動手段のステッピングモータ駆動回路ＳＤ１，ＳＤ２
は発振器ＯＳＣにより駆動される。Stepping motor drive circuit SD 1 , SD 2 of drive means
Is driven by the oscillator OSC.
ステッピングモータＳＭ１により回転させられる２分の
１波長板ＨＷＰに対して直線偏光子ＬＰ１がステッピン
グモータＳＭ２により同期回転させられる点は前述のと
おりである。As described above, the linear polarizer LP 1 is synchronously rotated by the stepping motor SM 2 with respect to the half-wave plate HWP rotated by the stepping motor SM 1 .
演算処理装置の位相計ＰＭの出力が接続されているロッ
クインアンプＬＡの参照信号として、２分の１波長板Ｈ
ＷＰに取り付けられ一体に回転する４分割形の光チョッ
パＯＣの出力が用いられる。光チョッパＯＣのＬＥＤお
よび光検出器によって得られる２分の１波長板ＨＷＰの
回転周波数の４倍の参照信号がロックインアンプＬＡに
接続される。そして、２分の１波長板ＨＷＰの回転周波
数の４倍の周波数成分を同期検出して、その振幅と基準
点からの位相差より測定試料の複屈折量と進相軸方位が
得られる。The half-wave plate H is used as a reference signal of the lock-in amplifier LA to which the output of the phase meter PM of the arithmetic processing unit is connected.
The output of a quadrant type optical chopper OC that is attached to the WP and rotates integrally is used. A reference signal that is four times the rotation frequency of the half-wave plate HWP obtained by the LED and the photodetector of the optical chopper OC is connected to the lock-in amplifier LA. Then, the frequency component four times the rotation frequency of the half-wave plate HWP is synchronously detected, and the birefringence amount and the fast axis direction of the measurement sample can be obtained from the amplitude and the phase difference from the reference point.
この方法によってロックインアンプＬＡの出力と位相を
出力装置であるレコーダＣＲに記録する。この装置の特
徴は測定時間を前述した装置に比べ短くできることであ
る。By this method, the output and phase of the lock-in amplifier LA are recorded in the recorder CR which is an output device. The feature of this device is that the measuring time can be shortened as compared with the above-mentioned device.
（発明の効果） 以上詳しく説明したように、本発明による自動複屈折測
定装置では、測定試料の光学的歪による複屈折量を、２
周波直交偏光光波を干渉して得られる光ビート交流信号
の位相ずれとして測定できる。(Effects of the Invention) As described in detail above, in the automatic birefringence measuring apparatus according to the present invention, the birefringence amount due to the optical strain of the measurement sample is set to 2
It can be measured as the phase shift of the optical beat AC signal obtained by interfering the orthogonally polarized light waves.
かつ、その進相軸方位も２分の１波長板の回転角度から
容易に得られる。In addition, the fast axis direction can be easily obtained from the rotation angle of the half-wave plate.
演算処理装置にＣＰＵを用いるとＣＰＵ制御による複屈
折測定が可能となり高精度かつ簡単な測定システムを構
成することが可能である。When a CPU is used for the arithmetic processing unit, the birefringence measurement under the control of the CPU becomes possible, and a highly accurate and simple measurement system can be constructed.
また、演算処理装置にロックインアンプを使用する装置
では簡便迅速な測定が可能となる。In addition, a device that uses a lock-in amplifier as an arithmetic processing device enables simple and quick measurement.
第１図は、本発明による自動複屈折測定装置の実施例を
示すブロック図である。 第２図は、本発明による他の自動複屈折測定装置の実施
例を示すブロック図である。 第３図は、従来の２周波直交偏光光源による複屈折測定
装置の基本構成をブロック図である。 Ｌ……２周波数直交偏光レーザ光源 ＨＭ……半透鏡 ＨＷＰ……２分の１波長板 Ｓ……測定試料 ＬＰ１，ＬＰ２……直線偏光子 ＰＨ１，ＰＨ２……光電検出器 ＳＭ１，ＳＭ２……ステッピングモータ ＳＤ１，ＳＤ２……ステッピングモータ駆動回路 ＡＤＣ……アナログ−ディジタル変換器 ＣＰＵ……中央処理装置 ＦＦＴ……フーリエ変換器 ＰＩ……フォトインタラプタ ＬＡ……ロックインアンプ ＯＳＣ……発振器 ＣＲ……記録計 ＰＭ……位相計 ＯＣ……光チョッパーFIG. 1 is a block diagram showing an embodiment of an automatic birefringence measuring device according to the present invention. FIG. 2 is a block diagram showing an embodiment of another automatic birefringence measuring device according to the present invention. FIG. 3 is a block diagram showing the basic configuration of a conventional birefringence measuring device using a dual-frequency orthogonal polarization light source. L ...... 2 frequency orthogonally polarized laser light source HM ...... half mirror HWP ...... 1 half-wave plate S ...... sample LP 1, LP 2 ...... linear polarizer PH 1, PH 2 ...... photoelectric detector SM 1 , SM 2 ...... Stepping motor SD 1 , SD 2 ...... Stepping motor drive circuit ADC ...... Analog-digital converter CPU ...... Central processing unit FFT ...... Fourier converter PI ...... Photo interrupter LA ...... Lock-in amplifier OSC …… Oscillator CR …… Recorder PM …… Phase meter OC …… Optical chopper
Claims (2)
ら成る２周波直交偏光レーザ光源と、前記レーザ光源の
光軸上に対向して配置されている光電検出器と、前記レ
ーザ光源と光電検出器を結ぶ光路中に光軸の周りに回転
可能に配置されている２分の１波長板と、前記光路中に
前記２分の１波長板に続いて配置され光軸の周りに回転
可能に配置される直線偏光子と、前記２分の１波長板と
直線偏光子との間に設けられている複屈折測定試料配置
部と、前記２分の１波長板の回転に対して前記直線偏光
子の回転が２倍になるように同期させて駆動する駆動手
段と、前記２分の１波長板が１回転した時光電検出器に
よって得られる検出出力を処理して進相軸方位または複
屈折量を測定する演算処理装置から構成した自動複屈折
測定装置。1. A dual-frequency orthogonal polarization laser light source composed of two orthogonal polarization components having a frequency difference, a photoelectric detector arranged on the optical axis of the laser light source so as to face each other, and the laser light source and the photoelectric light source. A half-wave plate rotatably arranged around the optical axis in the optical path connecting the detectors, and a half-wave plate arranged in the optical path following the half-wave plate and rotatable around the optical axis And a linear polarizer disposed between the half-wave plate and the linear polarizer, and the straight line with respect to the rotation of the half-wave plate. Driving means for driving the polarizer in synchronism so that the rotation is doubled, and processing the detection output obtained by the photoelectric detector when the half-wave plate makes one rotation to process the fast axis direction or complex An automatic birefringence measuring device comprising an arithmetic processing unit for measuring the amount of refraction.
ら成る２周波直交偏光レーザ光源と、前記レーザ光源の
光軸上に対向して配置されている光電検出器と、前記レ
ーザ光源と光電検出器を結ぶ光路中に光軸の周りに回転
可能に配置されている２分の１波長板と、前記光路中に
前記２分の１波長板に続いて配置され光軸の周りに回転
可能に配置される直線偏光子と、前記２分の１波長板と
直線偏光子との間に設けられている複屈折測定試料配置
部と、前記２分の１波長板の回転に対して前記直線偏光
子の回転が２倍になるように同期させて駆動する駆動手
段と、前記２分の１波長板の回転周波数の４倍の交流信
号を参照信号とするロックインアンプにより得られる信
号から複屈折測定試料の進相軸方位または複屈折量を測
定する演算処理装置から構成した自動複屈折測定装置。2. A dual-frequency orthogonal polarization laser light source composed of two orthogonal polarization components having a frequency difference, a photoelectric detector disposed on the optical axis of the laser light source so as to face each other, the laser light source and the photoelectric detector. A half-wave plate rotatably arranged around the optical axis in the optical path connecting the detectors, and a half-wave plate arranged in the optical path following the half-wave plate and rotatable around the optical axis And a linear polarizer disposed between the half-wave plate and the linear polarizer, and the straight line with respect to the rotation of the half-wave plate. A drive means for driving the polarizer in synchronism so that the rotation of the polarizer is doubled and a signal obtained by a lock-in amplifier using an AC signal having a frequency four times the rotation frequency of the half-wave plate as a reference signal. Arithmetic processor for measuring the fast axis direction or birefringence of refraction measurement sample Automatic birefringence measuring apparatus composed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23721288A JPH0612333B2 (en) | 1988-09-20 | 1988-09-20 | Automatic birefringence measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23721288A JPH0612333B2 (en) | 1988-09-20 | 1988-09-20 | Automatic birefringence measuring device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0283428A JPH0283428A (en) | 1990-03-23 |
| JPH0612333B2 true JPH0612333B2 (en) | 1994-02-16 |
Family
ID=17012046
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23721288A Expired - Lifetime JPH0612333B2 (en) | 1988-09-20 | 1988-09-20 | Automatic birefringence measuring device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0612333B2 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH046444A (en) * | 1990-04-25 | 1992-01-10 | Hoya Corp | Method and apparatus for measuring photo-elastic constant |
| JP2713190B2 (en) * | 1994-10-31 | 1998-02-16 | 日本電気株式会社 | Optical property measuring device |
| FR2756919B1 (en) * | 1996-12-06 | 1999-02-12 | Armines | ELLIPSOMETER WITH ROTATING BIREFRINGENT BLADE |
| TW561254B (en) * | 2001-09-26 | 2003-11-11 | Nikon Corp | Aberration measuring device, aberration measuring method, regulation method for optical system, and exposure system provided with optical system regulated by the regulation method |
| WO2007099791A1 (en) * | 2006-02-28 | 2007-09-07 | National University Corporation Tokyo University Of Agriculture And Technology | Measuring instrument and measuring 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 |
| 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 |
| CN106813901B (en) * | 2017-01-16 | 2018-12-25 | 中国科学院上海光学精密机械研究所 | The measuring device and its measurement method of optical device phase-delay quantity |
-
1988
- 1988-09-20 JP JP23721288A patent/JPH0612333B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0283428A (en) | 1990-03-23 |
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