JPH056540Y2 - - Google Patents

Description

【考案の詳細な説明】 〔産業上の利用分野〕 本考案は、電界強度を光学的に検出する光学式
電界検出器に関し、更に詳細すれば同時に２方向
の電界を検出できる光学式電界検出器に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical electric field detector that optically detects electric field intensity, and more specifically, an optical electric field detector that can detect electric fields in two directions simultaneously. Regarding.

〔従来技術〕[Prior art]

光学式電界検出器は、ポツケルス効果、つまり
電界強度に応じて電界検出素子の屈折率が変化す
る現象を利用して電界の強さを検出するものであ
り、電界内に置く電界検出素子として水晶が用い
られたものがある。 Optical electric field detectors detect the strength of an electric field by utilizing the Pockels effect, a phenomenon in which the refractive index of the electric field detection element changes depending on the electric field strength, and uses a crystal as the electric field detection element placed within the electric field. is used in some cases.

この光学式電界検出器は第５図に示す如く、発
光部３１から出力された光が光フアイバ３２及び
レンズ系３３を経て偏光子３４に入射されて直線
偏光され、次いでλ／４板３５へ入射されて、こ
れを通過する間に円偏光され、その円偏光波は直
方体形状の水晶３６に入射される。水晶３６は電
界を受けるとポツケルス効果により屈折率が変化
し、入射された円偏光波は楕円偏光波となる。水
晶３６を通過した楕円偏光波は直角プリズム付き
偏光子３７にて２回反射され、この反射の際に直
線偏光され、入射した向きと逆向きに方向を変え
て直角プリズム付き偏光子３７から直線偏光波と
なつて出射され、レンズ系３８及び光フアイバ３
９を経て受光部４０へ入射される。前記楕円偏光
波と電界強度とには相関関係（楕円偏光波の偏平
度が大きい程電界強度は強い）があるので、受光
部４０は、入射した直線偏光波の強度に基づき、
前記相関関係を参照して電界の強度を検出する。 In this optical electric field detector, as shown in FIG. The circularly polarized light wave is incident on the rectangular parallelepiped-shaped crystal 36 and is circularly polarized while passing through this. When the crystal 36 receives an electric field, its refractive index changes due to the Pockels effect, and the incident circularly polarized light wave becomes an elliptically polarized light wave. The elliptically polarized light wave that passed through the crystal 36 is reflected twice by the polarizer 37 with a right-angle prism, and upon this reflection, it becomes linearly polarized, changes its direction in the opposite direction to the direction of incidence, and leaves the polarizer 37 with a right-angle prism in a straight line. It is emitted as a polarized light wave, and is transmitted to the lens system 38 and the optical fiber 3.
9 and enters the light receiving section 40. Since there is a correlation between the elliptically polarized light wave and the electric field strength (the greater the degree of flatness of the elliptically polarized light wave, the stronger the electric field strength is), the light receiving unit 40 receives
The strength of the electric field is detected with reference to the correlation.

〔考案が解決しようとする問題点〕[Problem that the invention attempts to solve]

電界検出素子は所定方向に入射された光に直交
する一方向の電界しか検出できないので、電界の
方向が不明な領域において任意の平面上の電界を
検出しようとする場合には、水晶を回転させ、取
り出す直線偏光波の振幅が最大となるように水晶
の角度を設定して電界を検出するか、またはこの
ような電界検出器を、その検出方向が垂直をなす
ように２回位置決めし、夫々の場合にて電界を検
出してベクトル和を求める必要があつた。ところ
が、前者の方法では水晶を回転させる作業が煩わ
しく、また、後者の方法では２回の検出操作を要
するという作業効率上の問題点があつた。 An electric field detection element can only detect an electric field in one direction perpendicular to light incident in a predetermined direction, so when trying to detect an electric field on an arbitrary plane in an area where the direction of the electric field is unknown, it is necessary to rotate the crystal. , the electric field is detected by setting the angle of the crystal so that the amplitude of the linearly polarized light wave to be extracted is maximized, or such an electric field detector is positioned twice so that its detection direction is perpendicular, and the electric field is detected twice. In this case, it was necessary to detect the electric field and find the vector sum. However, in the former method, the work of rotating the crystal is troublesome, and in the latter method, two detection operations are required, which is a problem in terms of work efficiency.

本考案はかかる事情に鑑みてなされたものであ
り、偏光子にて２方向に直線偏光した光を夫々円
偏光して検出方向が異なる２個の電界検出素子に
各別に入射し、各電界検出素子からの光を検出す
る構成とすることにより、同時に２方向の電界が
求められ、電界の方向が不明な領域においてもそ
の２次元方向及びその強さを１回の検出操作にて
検出でき、しかも検出するための装置が小型であ
る光学式電界検出器を提供することを目的とす
る。 The present invention was developed in view of the above circumstances, and the light linearly polarized in two directions by a polarizer is circularly polarized and incident on two electric field detection elements with different detection directions, respectively. By adopting a configuration that detects light from the element, electric fields in two directions can be determined simultaneously, and even in areas where the direction of the electric field is unknown, the two-dimensional direction and its strength can be detected with a single detection operation. Moreover, it is an object of the present invention to provide an optical electric field detector whose detection device is small in size.

〔問題点を解決するための手段〕[Means for solving problems]

本考案に係る光学式電界検出器は、偏光子にて
直線偏光された光を円偏光し、この円偏光波を、
電界強度に応じた偏平度の楕円偏光波になす電界
検出素子に入射し、電界検出素子からの光を受光
して電界の強度を検出するようになした光学式電
界検出器において、光を２方向に直線偏光する偏
光子と、該偏光子からの直線偏光波を円偏光する
円偏光手段と、電界検出方向を異ならせて位置決
めしてあり、前記円偏光手段からの円偏光波を各
別に入射する２個の電界検出素子と、各電界検出
素子からの光を受光してその光の強度を検出する
受光部とを具備することを特徴とする。 The optical electric field detector according to the present invention circularly polarizes linearly polarized light with a polarizer, and converts this circularly polarized wave into
In an optical electric field detector, the intensity of the electric field is detected by inputting the light into an elliptically polarized wave with a degree of flatness corresponding to the electric field intensity, and detecting the intensity of the electric field by receiving the light from the electric field detection element. A polarizer that linearly polarizes light in a direction, and a circular polarizer that circularly polarizes a linearly polarized wave from the polarizer are positioned in different electric field detection directions, and the circularly polarized wave from the circular polarizer is separately polarized. It is characterized by comprising two incident electric field detection elements and a light receiving section that receives light from each electric field detection element and detects the intensity of the light.

〔作用〕[Effect]

偏光子にて直線偏光して得られる２方向の直線
偏光波を夫々円偏光し、その円偏光波を検出方向
が異なる２個の電界検出素子に各別に入射する。
そして各電界検出素子からの光を検出する。そう
すると２方向の電界が同時に検出される。 Linearly polarized waves in two directions obtained by linearly polarizing with a polarizer are each circularly polarized, and the circularly polarized waves are separately incident on two electric field detection elements having different detection directions.
Then, light from each electric field detection element is detected. Then, electric fields in two directions are detected simultaneously.

〔実施例〕〔Example〕

以下、本考案をその実施例を示す図面に基づき
説明する。第１図は本考案に係る光学式電界検出
器（以下本案検出器という）の平面模式図、第２
図は第１図の−線における正面模式図、第３
図は偏光状態を示す模式図であり、図中１は発光
部を示す。発光部１からの光（ランダムな方向に
振動部分をもつている。）〔第３図ａ参照〕は、発
光用光フアイバ２及びレンズ系３を経て、プリズ
ム面４ａを有する偏光子４に入射される。偏光子
４は入射した光を垂直な２方向に直線偏光する作
用を有し、偏光子４に入射された光はここで２方
向に直線偏光される〔第３図ｂ参照〕。 Hereinafter, the present invention will be explained based on drawings showing embodiments thereof. Figure 1 is a schematic plan view of the optical electric field detector according to the present invention (hereinafter referred to as the detector of the present invention);
The figure is a schematic front view taken along the - line in Figure 1.
The figure is a schematic diagram showing the polarization state, and 1 in the figure indicates a light emitting part. Light from the light emitting unit 1 (having vibrating parts in random directions) [see Figure 3a] passes through the light emitting optical fiber 2 and the lens system 3, and enters the polarizer 4 having a prism surface 4a. be done. The polarizer 4 has the function of linearly polarizing incident light in two perpendicular directions, and the light incident on the polarizer 4 is linearly polarized in two directions [see FIG. 3b].

２方向に直線偏光された光のうち、直進する第
１の直線偏光波はそのまま直進し、進路が90°変
向された第２の直線偏光波は偏光子４のプリズム
面４ａにて反射され、前記第１の直線偏光波と同
一方向に進む。各直線偏光波は円偏光手段たる
λ／４板５に入射されてこれを透過する間に円偏
光され〔第３図ｃ参照〕、その第１及び第２の円
偏光波は夫々電界検出素子たる水晶６ａ，６ｂに
入射される。 Of the light linearly polarized in two directions, the first linearly polarized wave continues straight, and the second linearly polarized wave whose path is deflected by 90° is reflected by the prism surface 4a of the polarizer 4. , traveling in the same direction as the first linearly polarized wave. Each linearly polarized light wave is incident on the λ/4 plate 5, which is a circularly polarizing means, and is circularly polarized while passing through this [see Fig. 3c], and the first and second circularly polarized waves are respectively detected by an electric field detection element. The light is incident on barrel crystals 6a and 6b.

水晶６ａ，６ｂは、何れもＺ軸方向に対して垂
直にカツトした両端を有するＺ−cut型水晶であ
つて、Ｚ軸方向に長い直方体状をなし、Ｚ軸方向
が一致しXY方向が互いに垂直をなすように（な
お第１図においてＺ軸方向は上下方向、Ｘ軸方向
は水晶６ａでは表裏方向、水晶６ｂでは左右方向
である）位置決めされている。前記第１及び第２
の円偏光波は、Ｚ軸方向に水晶６ａ，６ｂを透過
する間にＸ軸方向の電界を受けると楕円偏光波と
なり〔第３図ｄ参照〕、その状態で回転しつつ出
射側へ進行していく。 The crystals 6a and 6b are both Z-cut type crystals having both ends cut perpendicularly to the Z-axis direction, and are rectangular parallelepipeds long in the Z-axis direction, with the Z-axis direction coincident and the XY directions mutually aligned. They are positioned vertically (in FIG. 1, the Z-axis direction is the vertical direction, the X-axis direction is the front-back direction for the crystal 6a, and the left-right direction for the crystal 6b). Said first and second
When the circularly polarized light wave receives an electric field in the X-axis direction while transmitting through the crystals 6a and 6b in the Z-axis direction, it becomes an elliptically polarized light wave [see Figure 3 d], and in that state, it rotates and advances toward the output side. To go.

なお、前記水晶６ａ，６ｂのＺ軸方向長さは、
その長さに応じて偏光波の振動面の∝れ角が異な
るが、本実施例では楕円偏光波の最短径方向の成
分を取出すように定める。つまり、楕円偏光波の
水晶６ａ，６ｂでの入射側端面と出射側端面との
偏光波の振動面の∝れ角度が90度の整数倍となる
ようにする。 Note that the lengths of the crystals 6a and 6b in the Z-axis direction are as follows:
The angle of inclination of the vibration plane of the polarized light wave varies depending on its length, but in this embodiment, it is determined to extract the component in the direction of the shortest axis of the elliptically polarized light wave. That is, the deflection angle of the vibration plane of the polarized light wave between the incident side end face and the output side end face of the elliptically polarized wave crystals 6a and 6b is set to be an integral multiple of 90 degrees.

第４図は水晶６ａ，６ｂの出射側近傍を示す立
面視での内部模式図である。水晶６ａ，６ｂの出
射側には、直角二等辺三角柱状のプリズム７が直
角部に対向する面７ｃの一方の短辺側半分を接触
させて設けられており、プリズム７に入射した
夫々の光は前記直角部を含む２側面７ａ，７ｂに
て順次反射される。プリズム７に入射した各楕円
偏光波が第１回目に反射される側面７ａにはプリ
ズム７と同一形状でこれよりも小さい検光子８
が、その直角部と対向する面を接触させて設けら
れており、側面７ａにて反射される光は検光子８
により夫々最短径方向の偏光波のみ反射されて
〔第３図ｅ参照〕、この各直線偏光波がもう一方の
側面７ｂにて反射されて前記面７ｃの他方の短辺
寄りの位置から入射した向きと逆向きに夫々出射
される。 FIG. 4 is a schematic internal view in elevation showing the vicinity of the output side of the crystals 6a and 6b. On the output side of the crystals 6a and 6b, a right-angled isosceles triangular prism-shaped prism 7 is provided with one short side half of the surface 7c facing the right angle portion in contact with each other, and each light incident on the prism 7 is is sequentially reflected at the two side surfaces 7a and 7b including the right angle portion. On the side surface 7a where each elliptically polarized light wave incident on the prism 7 is reflected for the first time, there is an analyzer 8 having the same shape as the prism 7 but smaller than it.
is provided with its right angle portion and the opposite surface in contact with each other, and the light reflected from the side surface 7a is reflected by the analyzer 8.
, only the polarized light waves in the shortest diameter direction are reflected [see Figure 3e], and each of these linearly polarized light waves is reflected from the other side surface 7b and enters the surface 7c from a position closer to the other short side. They are emitted in the opposite direction.

前記面７ｃには、夫々の光出射部分にレンズ系
９ａ，９ｂが接着されており、面７ｃから出射さ
れた各直線偏光波はレンズ系９ａ，９ｂを経て、
これに接続した受光用光フアイバ１０ａ，１０ｂ
を通過して受光部１１ａ，１１ｂにて捉えられ
る。 Lens systems 9a and 9b are bonded to the light emitting portions of the surface 7c, and each linearly polarized light wave emitted from the surface 7c passes through the lens systems 9a and 9b.
Light receiving optical fibers 10a, 10b connected to this
The light passes through and is captured by the light receiving sections 11a and 11b.

受光部１１ａ，１１ｂは、光を電気信号として
取出す光電変換素子、光の振幅測定を行う回路及
び入射光の強度レベルと電界の強度との関係を示
す相関関数を記憶している演算回路を備えてお
り、入射した光の強度に基づき、つまり直線偏光
波の振幅に基づき電界の強度を求める。 The light receiving sections 11a and 11b include a photoelectric conversion element that extracts light as an electric signal, a circuit that measures the amplitude of light, and an arithmetic circuit that stores a correlation function that indicates the relationship between the intensity level of incident light and the intensity of the electric field. The intensity of the electric field is determined based on the intensity of the incident light, that is, the amplitude of the linearly polarized wave.

本案検出器はこのように構成されており、λ／
４板より出射した円偏光波は水晶６ａ，６ｂ内を
透過する間に、水晶６ａ，６ｂに印加される電界
の強度に応じて、水晶での電界検出方向を大径と
し、それと直交する方向を小径とする楕円偏光波
となる。この楕円偏光波の偏平度は電界強度が強
い程大きく、また電界強度が弱い程小さくなり、
電界強度と相関があることが公知である。そして
楕円偏光波の最短径方向成分の光の強度を受光部
１１ａ，１１ｂにて検出し、その検出値と前記相
関関数とに基づき電界強度を検出する。 The proposed detector is configured in this way, and λ/
While the circularly polarized light waves emitted from the four plates pass through the crystals 6a and 6b, depending on the strength of the electric field applied to the crystals 6a and 6b, the direction in which the electric field is detected in the crystal is set to the large diameter, and the direction perpendicular to that direction is determined. It becomes an elliptically polarized light wave with a small diameter. The degree of flatness of this elliptically polarized light wave increases as the electric field strength increases, and decreases as the electric field strength decreases.
It is known that there is a correlation with electric field strength. Then, the light intensity of the shortest diameter component of the elliptically polarized light wave is detected by the light receiving sections 11a and 11b, and the electric field intensity is detected based on the detected value and the correlation function.

この際本実施例では、Ｚ−cut型水晶６ａ，６
ｂが、Ｚ軸方向を一致させXY方向が垂直をなす
ように位置決めされているので、Ｚ軸方向に直交
する２方向の電界を検出できる。 At this time, in this embodiment, Z-cut type crystals 6a, 6
b are positioned so that the Z-axis directions coincide and the XY directions are perpendicular, so that electric fields in two directions perpendicular to the Z-axis direction can be detected.

なお、本実施例では電界検出方向が垂直をなす
ように２個の水晶を位置決めする場合について説
明したが、その電界検出方向が異なつていれば、
同時に２方向の電界を検出できることは言うまで
もない。 In this embodiment, the case where two crystals are positioned so that the electric field detection directions are perpendicular has been explained, but if the electric field detection directions are different,
Needless to say, electric fields in two directions can be detected simultaneously.

また、本実施例では電界検出素子として水晶を
用いる場合につき説明したが、これに限らず、ポ
ツケルス効果を有するものであれば何れの光学材
料を用いてもよいことは勿論である。 Further, in this embodiment, a case has been described in which a crystal is used as the electric field detection element, but the present invention is not limited to this, and it goes without saying that any optical material having the Pockels effect may be used.

〔効果〕〔effect〕

以上詳述した如く本案検出器では、従来のよう
に電界検出素子（水晶）を回転させる必要がなく
容易に、しかも同時に直角な２方向の電界を検出
できる。 As described in detail above, in the present detector, it is not necessary to rotate the electric field detection element (crystal) as in the conventional case, and electric fields in two orthogonal directions can be detected easily and simultaneously.

また、従来は使用していなかつた偏光子からの
一方向の直線偏光波〔第５図Ａ参照〕を利用する
ので、新たな光源（発光部）を追加する必要がな
い。 Furthermore, since a unidirectional linearly polarized light wave from a polarizer (see FIG. 5A), which has not been used in the past, is used, there is no need to add a new light source (light emitting section).

更に、本案検出器は従来の電界検出器に電界検
出素子（水晶）、受光用光フアイバ及び受光部を
一組だけを追加すれば、同時に直角な２方向の電
界を検出できるので、装置全体が小型である等本
考案は優れた効果を奏する。 Furthermore, the proposed detector can detect electric fields in two perpendicular directions at the same time by adding only one set of an electric field detection element (crystal), a light receiving optical fiber, and a light receiving part to a conventional electric field detector, so the entire device can be The present invention has excellent effects such as being small.

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

第１図は本案検出器の平面模式図、第２図は第
１図の−線における正面模式図、第３図は偏
光状態を示す模式図、第４図は第１図の部分立面
構造図、第５図は従来の電界検出器の模式図であ
る。 １……発光部、２……発光用光フアイバ、４…
…偏光子、５……λ／４波長板、６ａ，６ｂ……
水晶、７……プリズム、８……検光子、１０ａ，
１０ｂ……受光用光フアイバ、１１ａ，１１ｂ…
…受光部。 Fig. 1 is a schematic plan view of the proposed detector, Fig. 2 is a schematic front view along the - line in Fig. 1, Fig. 3 is a schematic diagram showing the polarization state, and Fig. 4 is a partial elevational structure of Fig. 1. FIG. 5 is a schematic diagram of a conventional electric field detector. 1... Light emitting section, 2... Optical fiber for light emission, 4...
...Polarizer, 5...λ/4 wavelength plate, 6a, 6b...
Crystal, 7... Prism, 8... Analyzer, 10a,
10b... Optical fiber for light reception, 11a, 11b...
…Light receiving section.

Claims (1)

【実用新案登録請求の範囲】 １ 偏光子にて直線偏光された光を円偏光し、こ
の円偏光波を、電界強度に応じた偏平度の楕円
偏光波になす電界検出素子に入射し、電界検出
素子からの光を受光して電界の強度を検出する
ようになした光学式電界検出器において、 光を２方向に直線偏光する偏光子と、該偏光
子からの直線偏光波を円偏光する円偏光手段
と、電界検出方向を異ならせて位置決めしてあ
り、前記円偏光手段からの円偏光波を各別に入
射する２個の電界検出素子と、各電界検出素子
からの光を受光してその光を強度を検出する受
光部とを具備することを特徴とする光学式電界
検出器。 ２ 前記２個の電界検出素子の電界検出方向は互
いに垂直をなす実用新案登録請求の範囲第１項
記載の光学式電界検出器。[Claims for Utility Model Registration] 1. Linearly polarized light is circularly polarized by a polarizer, and this circularly polarized light wave is made into an elliptically polarized light wave with a degree of flatness according to the electric field intensity. An optical electric field detector that detects the intensity of an electric field by receiving light from a detection element includes a polarizer that linearly polarizes the light in two directions, and a polarizer that circularly polarizes the linearly polarized light wave from the polarizer. a circularly polarizing means, two electric field detecting elements which are positioned in different electric field detection directions and receive the circularly polarized light waves from the circularly polarizing means, and which receive light from each electric field detecting element. 1. An optical electric field detector comprising a light receiving section that detects the intensity of the light. 2. The optical electric field detector according to claim 1, wherein electric field detection directions of the two electric field detection elements are perpendicular to each other.