JPH0387670A - Device for measuring electric field by optical system - Google Patents

Abstract

PURPOSE:To facilitate the assembly, to simplify the constitution and to improve the S/N by forming a mirror consisting of a reflection film on the plate surface of the emission side of a wavelength plate, in the electric field measuring device of a reflection type. CONSTITUTION:A wavelength plate 21 is formed like a plate, for instance, by cutting a crystal of quartz at a prescribed angle, and on the plate surface of the emission side of this wavelength plate 21, a mirror 22 of a high reflection factor consisting of a thin film of a metal (example: Al) is formed by vacuum vapor deposition or spattering. This wavelength plate 21 is used by placing it on the emission side of an electro-optical crystal and irradiated with a light beam from a light source through a polarization beam splitter and a polarizer. Subsequently, an emitted light of the electro-optical crystal is reflected by the mirror 22 formed on the plate surface of the emission side of the wavelength plate 21, allowed to transmit through the electro-optical crystal again, separated by a polarization beam splitter, led to a photodetector and converted to an electric signal. In such a way, by forming integrally the wavelength plate 21 and the mirror 22, an optical alignment becomes unnecessary, the assembly is facilitated, and also, the constitution can be simplified.

Description

【発明の詳細な説明】 （発明の技術分野） 本発明は、電気光学結晶のボッケルス効果を利用して電
界を測定する光方式の電界測定装置に関する。DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an optical electric field measuring device that measures an electric field using the Bockels effect of an electro-optic crystal.

（発明の技術的背景とその問題点） 一般に、物質に電界を加えると、その光学的性質が変化
する。この現象は、広く電気光学効果と呼ばれ、ボッケ
ルス効果、カー効果等がよく知られている。この場合、
結晶の屈折率ｎは次式で与えられる。(Technical background of the invention and its problems) Generally, when an electric field is applied to a substance, its optical properties change. This phenomenon is widely called the electro-optic effect, and the Bockels effect, Kerr effect, etc. are well known. in this case,
The refractive index n of the crystal is given by the following equation.

ｎ＝ｎｏ＋ａＥ＋ｂＥ２＋　−−− ここでｎｏ：電界印加前の屈折率 Ｅ：印加電界 ここで、電界Ｅの１次の係数ａをボッケルス係数、２次
の係数すをカー係数という。n=no+aE+bE2+ --- where no: refractive index before electric field application E: applied electric field Here, the first-order coefficient a of the electric field E is called the Bockels coefficient, and the second-order coefficient is called the Kerr coefficient.

そして、このような電気光学効果を有する媒質（以下電
気光学結晶と称す）と光ファイバを絹み合わせた電界、
電圧測定装置が開発され、このような装置の電気光学結
晶では屈折率が電界の１次の項に比例するボッケルス効
果を利用している。Then, an electric field created by interweaving a medium with such an electro-optic effect (hereinafter referred to as an electro-optic crystal) and an optical fiber,
Voltage measurement devices have been developed that utilize the Bockels effect in which the refractive index of an electro-optic crystal is proportional to the first order term of the electric field.

すなわち、複屈折性の電気光学結晶中の常光線と異常光
線との間の位相変化は、入射する直線偏光の偏光面がこ
の結晶媒質を通る間に、ある角度回転することを利用し
ている。たとえば、円偏光の入射光は結晶の出射面では
楕円偏光となる。In other words, the phase change between ordinary and extraordinary rays in a birefringent electro-optic crystal utilizes the fact that the polarization plane of incident linearly polarized light rotates by a certain angle while passing through this crystal medium. . For example, incident circularly polarized light becomes elliptically polarized light at the exit surface of the crystal.

したがって、測定すべき電界中に電気光学結晶を置いて
、電界の変化にしたがってその結晶中に誘起される複屈
折変化を、偏光子、検光子等を用いて光１？！号の強度
の変化として検出することにより電界の変化を測定する
ことができる。Therefore, an electro-optic crystal is placed in the electric field to be measured, and the change in birefringence induced in the crystal as the electric field changes is measured using a polarizer, analyzer, etc. ! Changes in the electric field can be measured by detecting changes in the signal strength.

Claims (1)

【特許請求の範囲】 　電気光学結晶を透過する光線のボッケルス効果による
光学的な変化から電界を測定する反射型の電界測定装置
において、 光源と、 この光源からの光をビームスプリッタおよび偏光子を介
して入射させる電気光学結晶と、この電気光学結晶に設
けた測定すべき電界を印加する電極と、 上記電気光学結晶を透過した光を波長板および検光子を
介して再び上記光源へ向けて反射するミラーと、 ミラーで反射され上記電気光学結晶を透過した光を上記
ビームスプリッタで分離して光学的な変化から上記電界
を測定する電界測定部と、 を具備するものにおいて、 波長板の出射側板面に形成した反射膜からなるミラーを
設けたことを特徴とする光方式の電界測定装置。[Claims] A reflection-type electric field measuring device that measures an electric field from an optical change due to the Bockels effect of a light beam transmitted through an electro-optic crystal, comprising: a light source; and light from the light source is transmitted through a beam splitter and a polarizer. an electro-optic crystal that is incident on the electro-optic crystal, an electrode provided on the electro-optic crystal that applies an electric field to be measured, and a light that has passed through the electro-optic crystal that is reflected back toward the light source via a wave plate and an analyzer. a mirror; and an electric field measurement unit that separates the light reflected by the mirror and transmitted through the electro-optic crystal by the beam splitter and measures the electric field from optical changes, the output side plate surface of the wavelength plate An optical electric field measuring device characterized by being provided with a mirror made of a reflective film formed on.