JP2004061127A - Deflection angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deflection angle detector having a compact structure in spite of its long optical path length for widening a deflection angle detection area and performing detection with high precision. <P>SOLUTION: In this deflection angle detector detecting a deflection angle of an optical deflection element is provided with a light source 1 radiating light, a prism 2, a decentered lens 4, a detection reflection face 3 mounted in the optical deflection element arranged on the optical path of the light from the light source 1 switched via the prism 2, and an optical detector 5. The prism 2 is constructed of a first face 2a having a light transmission action, a second face 2b having a light reflection action and a light transmission action, and a third face 2c having a light reflection action and a light transmission action. The decentered lens 4 is constructed of a fourth face 4a facing the third face 2c and a fifth face 4b positioned between the fourth face 4a and the optical detector 5 and serving as a transparent face having positive power. <P>COPYRIGHT: (C)2004,JPO

Description

但し、上記式の第１項は球面項、第２項は自由曲面項である。また、球面項中、ｃは頂点の曲率、ｋはコーニック定数（円錐定数）、ｒ＝（Ｘ２＋Ｙ２）^１／２である。
自由曲面項は、次式のように展開することができる。但し、Ｃｊ（ｊは２以上の整数）は係数である。

なお、データの記載されていない非球面に関する項は０である。
また、屈折率については、ｄ線（波長５８７．５６ｎｍ）に対するものを表記してある。
長さの単位はｍｍである。
【００５５】
また、各実施例の数値データでは、設計の利便性を考慮して検出用反射面から後述する回動ミラー１５の反射面までの距離を０とし、検出用反射面の光軸位置に回転軸があるものとしている。
なお、実際には、検出用反射面と後述する回動ミラー１５の反射面との間には所定の距離があるが、検出用反射面上に回転軸を設けることにより、回動により回動ミラー１５の反射面の位置にズレを生じるが、回転角度を電気的に制御することにより補正できるので、検出用反射面から後述する回動ミラー１５の反射面までの距離を０としても、本発明の本質に影響を与えない。
また、以下の各数値データ中の絞り面は仮想絞り面であり、そこに実際に絞りがあることを示したものではない。さらに、有害光を除去するフレア絞りは必要により各面間隔中に設置することが可能である。
【００５６】

【００５７】

【００５８】

【００５９】

【００６０】

【００６１】

【００６２】

【００６３】

【００６４】

【００６５】

【００６６】

【００６７】

【００６８】

【００６９】

【００７０】

【００７１】
次に、上記実施例を用いて説明した本発明の偏向角検出装置を用いたシステムの例について説明する。
図１６は本発明の偏向角検出装置を用いた光信号スイッチシステム１０６の一例の概略構成を示す説明図である。
本システムは、情報信号に応じて、例えば強度・パルス幅・周波数などが変調されたレーザ光束１０３…（光信号）が内部に伝送されてくる光ファイバーケーブルなどの光伝送用ケーブルを束ねた入力側ケーブルユニット１００と、光ファイバーケーブルなどの光伝送用ケーブルを束ねて、レーザ光束１０３…を内部に伝送させる出力側ケーブルユニット１０５と、それらのユニットの間に設けられたレーザ光束１０３…を選択的に偏向するための光スイッチングデバイス１０８，１０８からなる。
【００７２】
入力側ケーブルユニット１００は、例えば紡糸されたガラスファイバーをプラスチックで保護被覆した光ファイバーケーブルなどから構成される光伝送用ケーブルの端部に、内部を伝送されてきたレーザ光束１０３を外部に出射させる出射口１０１ａを備えた入力側ケーブル１０１を複数本、束ねたものである。それぞれの出射口１０１ａの光軸上にレーザ光束１０３を平行光束とするよう機能するコリメータユニット１０２が配置されている。入力側ケーブル１０１は、それぞれの出射口１０１ａ…が出射方向を揃えられ、それぞれ所定の間隔をあけて規則正しく配列されている。出射口１０１ａ…は、その個数に応じて、例えば２×２、６４×６４などの格子マトリクス状に配列されている。
【００７３】
出力側ケーブルユニット１０５は、同様に前記光伝送用ケーブルの端部に、レーザ光束１０３を入射させる入射口１０９ａを備えた出力側ケーブル１０９を複数本、束ねたものである。それぞれの入射口１０９ａの光軸上に、レーザ光束１０３を結像するよう機能する結像ユニット１０７が配置されている。出力側ケーブル１０９は、それぞれの入射口１０９ａ…が入射方向を揃えられ、それぞれ所定の間隔があけて規則正しく配列されている。入射口１０９ａ…は、その個数に応じて、例えば２×２、６４×６４などの格子マトリクス状に配列されている。
【００７４】
入力側ケーブルユニット１００および出力側ケーブルユニット１０５の、レーザ光束１０３の出入射方向には、それぞれ光スイッチングデバイス１０８が配置されている。光スイッチングデバイス１０８は、１次元または２次元にそれぞれ独立に傾くことができる回動ミラー１５（光偏向素子）…と、それらの中立位置からの傾き角（偏向角）をそれぞれ検出する本発明の偏向角検出装置６０…と、偏向角検出装置６０からの出力により回動ミラー１５…の偏向角を制御する偏向角制御手段６１’とからなる。
【００７５】
光スイッチングデバイス１０８，１０８は、それらの回動ミラー１５…がそれぞれ出射口１０１ａ…、入射口１０９ａ…に対応するように配置されるとともに、回動ミラー１５…が中立位置の傾きとされた状態で、所定の出射口１０１ａから出射されたレーザ光束１０３がそれぞれの回動ミラー１５，１５で反射されて所定の入射口１０９ａに入射する位置関係に配置されている。
【００７６】
図１７は回動ミラー１５の反射面に直角な断面とそのまわりの構成を示す説明図である。
図１７の回動ミラー１５は、ガルバノミラーを採用した例である。例えば電磁コイルなどの周知のアクチュエータ１５ｄによって、傾き角を任意に調整できるように支持された板状の支持部材１５ｂの表裏面に、表面反射平面ミラーを埋め込むことにより、支持部材１５ｂの表面側にレーザ光束１０３を反射するための偏向ミラー面１５ａを、支持部材１５ｂの裏面側に検出用反射面１５ｃをそれぞれ形成したものである。
なお、本発明においては、上述のように検出用反射面１５ｃの面上に回転軸を設け、偏向ミラー面１５ａの位置ズレによる誤差を電気的に補正してもよいし、２つの面（１５ａ，１５ｃ）に回転軸を設け、リンク機構などを介して２つの面を同じ回転角で回転させるようにすることもできる。
【００７７】
偏向ミラー面１５ａと検出用反射面１５ｃは、平行である必要はないが、偏向ミラー面１５ａの偏向角に対応して検出用反射面１５ｃが傾斜するように接合されている。図示の例では、偏向ミラー面１５ａと検出用反射面１５ｃが、それぞれ支持部材１５ｂに固定されている。したがって、偏向ミラー面１５ａと検出用反射面１５ｃは回動中心を共有している。またそれぞれの面精度、反射率は適宜反射すべき検出光、レーザ光束１０３に対して適切となるように個別に設定される。
【００７８】
回動ミラー１５は、レーザ光束１０３…が入射する方向に偏向ミラー面１５ａ…が配され、背面側の検出用反射面１５ｃ…には、偏向角を検出するための偏向角検出装置６０…が対向するように設けられている。
【００７９】
偏向角制御手段６１’は、回動ミラー１５とその偏向角を特定する偏向角制御信号２０１と電源電圧２００を外部から受け取り、アクチュエータ１５ｄと偏向角検出装置６０にそれぞれ電気的に接続され、アクチュエータ１５ｄを駆動する駆動信号２０２を出力し、回動ミラー１５の偏向角を検出する偏向角検出装置６０から検出レベル信号２０３が入力されるように構成されている。
【００８０】
このように構成された光信号スイッチシステム１０６では、まず、通常の伝送路の中継状態では、１つの入力側ケーブル１０１において内部を伝送されたレーザ光束１０３は、格子マトリクス状に規則正しく配列された出射口１０１ａ…の１つに到達して、そこから入力側ケーブル１０１の外部に放射される。そしてコリメータユニット１０２によりその放射光が集光され、ゴミなどによるけられが発生しないように適宜太さの平行ビームとされて光スイッチングデバイス１０８の方向に出射される。
【００８１】
ここでコリメータユニット１０２のそれぞれの後段に設けられた、中立位置の回動ミラー１５…は、それぞれ、特定のレーザ光束１０３を、もう一方の光スイッチングデバイス１０８の中立位置にある特定の回動ミラー１５に向けて反射して、規則正しく配列された出力側ケーブルユニット１０５の特定の入射口１０９ａ…に対応する結像ユニット１０７…の１つに入射させている。そして入射した結像ユニット１０７を透過して、出力側ケーブルユニット１０５中の、所定の光ケーブル１０１の入射口１０９ａに結像されて、その内部にレーザ光束１０３が入射され、伝送されていく。
【００８２】
本例による光信号スイッチシステム１０６では、回動ミラー１５，１５を中立位置から所定の偏向角だけ傾斜させ、レーザ光束１０３の到達位置を変更することにより行う。例えば、図１４において、特定の入力側ケーブル１０１Ａから出射されるレーザ光束１０３Ａを通常の中継状態からスイッチングして出力側ケーブル１０９Ｂに切り換える場合、まず回動ミラー１５Ａの偏向角を変えてレーザ光束１０３Ａを回動ミラー１５Ｂに向けて偏向する。回動ミラー１５Ｂは、通常の中継状態では別のレーザ光束１０３を中立位置で出力側ケーブル１０９Ｂに入射させるが、この場合レーザ光束１０３Ａの入射角に対応して、レーザ光束１０３Ａが出力側ケーブル１０９Ｂに入射するように回動ミラー１５Ｂの偏向角が変更される。
【００８３】
出射口１０１ａ…と入射口１０９ａ…はそれぞれ規則正しく配列されているので、それぞれの出射口１０１ａと入射口１０９ａを対応させる回動ミラー１５，１５の偏向角は、光スイッチングデバイス１０８，１０８の位置関係によってあらかじめ決まっている。そこで、特定の回動ミラー１５，１５を所定の偏向角に傾斜させることにより、光信号スイッチングを行うことができる。
そのため、回動ミラー１５，１５の偏向角を上述した偏向角検出装置６０で検出して図１８に示す偏向角制御手段６１’を介してアクチュエータ１５ｄをフイードバック制御することになる。
【００８４】
次に本発明による偏向角検出装置を用いた装置の他の例として、回動ミラー１５を傾斜させて光信号スイッチング制御を行うための偏向角制御手段６１’について説明する。図１８はその制御ブロック図である。
偏向角制御手段６１’は、詳しくは、偏向角を特定する偏向角制御信号２０１をデコードし、回動ミラー１５の目標偏向角に対応した目標レベル信号２０４を発生させるデコード手段６１’ａと、偏向角検出装置６０からの検出レベル信号２０３と目標レベル信号２０４の偏差を受け取ってアクチュエータ５ｄの駆動信号２０２を発生させる制御部６１’ｂとからなる。
【００８５】
次に光信号スイッチング方法について、図１６および図１８を中心に説明する。
まず、スイッチングするレーザ光束１０３Ａの入力側ケーブル１０１Ａと出力側ケーブル１０９Ｂが特定される。そして、それぞれの情報が、偏向角制御信号２０１によって外部から、各光スイッチングデバイス１０８の偏向角制御手段６１’に入力され、デコード手段６１’ａに入力される。
【００８６】
デコード手段６１’ａにより回動ミラー１５の目標偏向角に対応する目標レベル信号２０４が発生される。目標レベル信号２０４は、検出された偏向角による検出レベル信号２０３との偏差が取られて制御部６１’ｂに入力される。制御部６１’ｂでは、この偏差を、例えば増幅、微分、積分などして、回動ミラー１５の偏向角を目標偏向角に近づけるように駆動信号２０２を調節してアクチュエータ１５ｄへフイードバックして出力する。
【００８７】
このように、偏向角検出装置６０を検出手段としてフイードバック制御が行われるので、回動ミラー１５の偏向角が目標偏向角に修正される。したがって、例えば外乱が生じて偏向角が目標偏向角からずれても、そのずれ量に応じてただちに目標偏向角に修正されるものである。すなわち、偏向角制御手段６１’と、偏向角検出装置６０とを備えた光スイッチングデバイス１０８により、リアルタイムのフイードバック制御が実現されている。
【００８８】
さらに、本発明の偏向角検出装置６０がコンパクトに構成されているために、光スイッチングデバイス１０８を小型化・省スペース化することができる。また、回動ミラー１５…の背後に配置される偏向角検出装置６０…がコンパクトであるために、回動ミラー１５の配列間隔を狭めることができるから、入力側ケーブルユニット１００、出力側ケーブルユニット１０５の光ケーブル１０１…の配列間隔もつめることができて、それぞれコンパクト化される。またその結果、回動ミラー１５の偏向角を大きくすることなく、切り替え可能な伝送路の数を増やすことができるという利点がある。
【００８９】
このような効果は、従来の光信号スイッチシステムにおいては採用されることのなかった凹面反射面を用いて光路を集光させながらコンパクトに折りたたむという本発明の特徴によって可能となったものである。
【００９０】
なお、上記の説明では、入力側ケーブルユニット１００の出射口１０１ａ…に対してそれぞれ１つの回動ミラー１５を備える例で説明した。しかし伝送路の切り替えの用途には、レーザ光束１０３を個々に切り替える場合以外の用途もある。例えば伝送路のメンテナンスなどの際にバックアップのための回線に切り替える場合である。この場合、所定の入力側ケーブルユニット１００の全体を、ある出力側ケーブルユニット１０５から別の出力側ケーブルユニット１０５へ切り替える。このような場合には、入力側ケーブルユニット１００の配列をそのまま保ちながら切り替えるので、回動ミラー１５は入力側ケーブルユニット１００に対して１つでもよい。
【００９１】
次に、本発明の偏向角検出装置を備えたピックアップ装置などの情報記録再生システムの例を説明する。図１９は本発明による偏向角検出装置を用いた情報記録再生システム１１０の概略構成を示す平面図である。
【００９２】
本システムは、情報信号を記録再生するための、例えば光ディスクや光磁気ディスクなどの記録ディスク１１２（記録媒体）と、情報信号に応じて例えば強度・パルス幅などが変調されたレーザ光束１１５（光束）を照射する半導体レーザ１（光源）と、レーザ光束１１５を結像する結像レンズ１１６および結像レンズユニット１１４と、レーザ光束１１５を偏向し結像レンズユニット１１４への入射位置を可変して微動トラッキング制御を行うためアクチュエータ（不図示）で偏向駆動される回動ミラー１５と、本発明の偏向角検出装置６０とからなる光学系と、それらの光学系を設置して記録ディスク１１２の記録面の平行方向と垂直方向に移動させることができるアーム１１３とを備える。
半導体レーザ１は、情報信号によって半導体レーザ１を変調するためのレーザ駆動手段１ｂに接続されている。
回動ミラー１５は、図１７に示した構成を採用することができる。偏向角検出装置６０も上述したいずれの実施例をも採用することができる。
【００９３】
符号１１１は筐体であって、その中に例えばＤＣ制御モータなどで回転駆動される駆動軸１１２ａに記録ディスク１１２が配置されている。記録ディスク１１２は駆動軸１１２ａ回りに回転可能に保持されている。
【００９４】
記録ディスク１１２は、少なくともいずれかの表面に光信号の記録または再生の一方または両方が可能な記録面を備えている。フォーマットされた記録ディスク１１２は、記録面の周方向にトラック信号が形成され、情報信号の記録位置を径方向に論理的に分割している。
【００９５】
アーム１１３は、記録面の上方に配置され、記録ディスク１１２に対して上下方向に弾性的に支持されている。アーム１１３は、回転軸１１３ａによって、記録ディスク１１２の記録面に平行方向に回転可能に支持されており、電磁コイルなどからなる駆動コイル１１７によって回転軸１１３ａ回りに回転駆動可能とされている。
【００９６】
結像レンズ１１６は、半導体レーザ１から出射されたレーザ光束１１５を、例えば平行ビームなどに適宜整形するよう構成されている。結像レンズユニット１１４は、レーザ光束１１５を受けて記録面上に結像するとともに、記録面からの反射光を受光して、情報信号に対応する信号光と、フォーカス制御を行うためのフォーカス検出光と、トラッキング制御を行うためのトラッキング検出光をそれぞれの受光素子に受光させるように構成されている。
【００９７】
結像レンズ１１６と結像レンズユニット１１４の間には、レーザ光束１１５の結像レンズユニット１１４への入射位置を可変して微動トラッキング制御を行うための回動ミラー１５が偏向角検出装置６０とともに配置されている。回動ミラー１５の構成は、図１７に示した構成を採用することができる。偏向角検出装置６０も上述したいずれの実施例をも採用することができる。
【００９８】
このように構成された本システムでは、まず、レーザ光束１１５を記録ディスク１１２の記録面に照射し、反射光を結像レンズユニット１１４で受光してトラッキング信号を拾い、トラックの位置、トラックからのずれ量などの情報を収集する。その情報に基づき、駆動コイル１１７によってアーム１１３の回動位置を粗動制御し、トラック間の移動や、トラックへの追従を行う。
【００９９】
さらに、より厳密なトラッキングを行うため、回動ミラー１５を傾斜させ、レーザ光束１１５を偏向させて、その結像レンズユニット１１４への入射位置をずらし、記録面上の径方向の結像位置を微動させる。その際、偏向角検出装置６０により回動ミラー１５の偏向角を検出してフイードバック制御する。フイードバック制御は、図１８を用いて説明した光信号スイッチング方法と同様の方法を採用することができる。
【０１００】
このように、本発明の偏向角検出装置６０を用いて情報記録再生システムを構成すると、第１に偏向角検出装置６０をコンパクトに構成することができるから、アーム１１３を小さく軽く構成することができる。したがって、その機械的な応答特性を高めることができるという利点がある。第２に偏向角検出装置６０の検出範囲が広くとることができるので、より大きな偏向角を取ることができ、回動ミラー１５から結像レンズユニット１１４までの距離が短くても所定の入射位置を得ることができ、その結果、アーム１１３上の光学系の光路長を短くすることができる。そのことによって、アーム１１３を小型化でき、よりコンパクトで機械的な応答特性に優れる情報記録再生システムを得ることができるという利点がある。
【０１０１】
以上説明したように、本発明の偏向角検出装置は、特許請求の範囲に記載された発明の他に、次に示すような特徴も備えている。
【０１０２】
（１）前記光源と前記検出用反射面との間の光路中に、屈折率が１以上の媒質で満たされたプリズムが配置されていることを特徴とする請求項１に記載の偏向角検出装置。
【０１０３】
（２）前記光源と前記検出用反射面との間の光路中に配置した前記プリズムの一部を、前記検出用反射面から前記光検出器に至るまでの光路の一部が通るようにしたことを特徴とする上記（１）に記載の偏向角検出装置。
【０１０４】
（３）前記プリズムと前記光検出器との間に、前記正のパワーを有する透過面を含む第２のプリズムが配置されていることを特徴とする上記（２）に記載の偏向角検出装置。
【０１０５】
（４）前記プリズムと前記第２のプリズムとが接合されていることを特徴とする上記（３）に記載の偏向角検出装置。
【０１０６】
（５）前記光路変換面が、光の一部を反射又は透過するビームスプリッタ面として構成されていることを特徴とする請求項１、上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１０７】
（６）前記光路変換面が、光の偏光状態に応じて、該光を反射又は透過する偏光ビームスプリッタ面として構成されていることを特徴とする請求項１、上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１０８】
（７）前記光路変換面が、光の入射角又は波長に応じて、該光を反射又は透過するホログラフィック面として構成されていることを特徴とする請求項１、上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１０９】
（８）前記光路変換面が、光の入射角に応じて、該光を透過又は全反射する面として構成されていることを特徴とする請求項１、上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１１０】
（９）前記光路変換面が、正のパワーを有することを特徴とする請求項１、上記（１）〜（８）のいずれかに記載の偏向角検出装置。
【０１１１】
（１０）前記光路変換面が、曲面で構成されていることを特徴とする上記（９）に記載の偏向角検出装置。
【０１１２】
（１１）前記光路変換面が、球面で構成されていることを特徴とする上記（９）に記載の偏向角検出装置。
【０１１３】
（１２）前記光路変換面が、回転対称非球面で構成されていることを特徴とする上記（９）に記載の偏向角検出装置。
【０１１４】
（１３）前記光路変換面が、非回転対称面で構成されていることを特徴とする上記（９）に記載の偏向角検出装置。
【０１１５】
（１４）前記光路変換面が、平面で構成されていることを特徴とする請求項１、上記（１）〜（８）のいずれかに記載の偏向角検出装置。
【０１１６】
（１５）前記検出用反射面に対向して配置された面を有し、該対向して配置された面が、入射面と反射面とを兼ねることを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１１７】
（１６）前記検出用反射面に対向して配置された面を有し、該対向して配置された面が、内部反射作用と透過作用とを有することを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１１８】
（１７）前記検出用反射面に対向して配置された面を有し、該対向して配置された面が、全反射による内部反射作用を有することを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１１９】
（１８）前記検出用反射面に対向して配置された面を有し、該対向して配置された面が、平面で構成されていることを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１２０】
（１９）前記検出用反射面に対向して配置された面を有し、該対向して配置された面が、曲面で構成されていることを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１２１】
（２０）前記検出用反射面に対向して配置された面を有し、該対向して配置された面が、球面で構成されていることを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１２２】
（２１）前記検出用反射面に対向して配置された面を有し、該対向して配置された面が、回転対称非球面で構成されていることを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１２３】
（２２）前記検出用反射面に対向して配置された面を有し、該対向して配置された面が、非回転対称面で構成されていることを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１２４】
（２３）前記光源と前記光路変換面との間に、正のパワーを有する光学部材が配置されていることを特徴とする請求項１に記載の偏向角検出装置。
【０１２５】
（２４）前記光源に対向した前記プリズムの入射面が、正のパワーを有することを特徴とする上記（１）〜（４）のいずれかに記載の偏向角検出装置。
【０１２６】
（２５）前記正のパワーを有する透過面が、球面を有する面で構成されていることを特徴とする請求項１、上記（１）〜（２４）のいずれかに記載の偏向角検出装置。
【０１２７】
（２６）前記正のパワーを有する透過面が、回転対称非球面を有する面で構成されていることを特徴とする請求項１、上記（１）〜（２４）のいずれかに記載の偏向角検出装置。
【０１２８】
（２７）前記正のパワーを有する透過面が、非回転対称面を有する面で構成されていることを特徴とする請求項１、上記（１）〜（２４）のいずれかに記載の偏向角検出装置。
【０１２９】
（２８）前記正のパワーを有する透過面が、フレネル面を有する面で構成されていることを特徴とする請求項１、上記（１）〜（２４）のいずれかに記載の偏向角検出装置。
【０１３０】
（２９）前記光検出器が、１次元のＰＳＤ（位置検出装置）で構成されていることを特徴とする請求項１、上記（１）〜（２８）のいずれかに記載の偏向角検出装置。
【０１３１】
（３０）前記光検出器が、２次元のＰＳＤ（位置検出装置）で構成されていることを特徴とする請求項１、上記（１）〜（２８）のいずれかに記載の偏向角検出装置。
【０１３２】
（３１）前記光検出器が、４分割の受光面を備えていることを特徴とする請求項１、上記（１）〜（２８）のいずれかに記載の偏向角検出装置。
【０１３３】
（３２）前記第２面における反射作用が全反射作用であることを特徴とする請求項２に記載の偏向角検出装置。
【０１３４】
（３３）前記第３面がハーフミラー面として構成されていることを特徴とする請求項２に記載の偏向角検出装置。
【０１３５】
（３４）前記第３面が偏光ビームスプリッタ面として構成されていることを特徴とする請求項２に記載の偏向角検出装置。
【０１３６】
（３５）前記第３面が回折光学面として構成されていることを特徴とする請求項２に記載の偏向角検出装置。
【０１３７】
（３６）前記第３面がホログラフィック光学面として構成されていることを特徴とする請求項２に記載の偏向角検出装置。
【０１３８】
（３７）前記第３面と前記第４面とが接合されていることを特徴とする請求項２に記載の偏向角検出装置。
【０１３９】
（３８）前記第１面が正のパワーを有する面として構成されていることを特徴とする請求項２に記載の偏向角検出装置。
【０１４０】
（３９）前記第１〜第５面がフレネル面で構成されていることを特徴とする請求項２に記載の偏向角検出装置。
【０１４１】
（４０）前記第２面における反射作用が全反射作用であることを特徴とする請求項３に記載の偏向角検出装置。
【０１４２】
（４１）前記第２面が、反射作用を有する部位と、該プリズムから前記光検出器側へ射出する作用とを有する部位のいずれにおいても正のパワーを有する面として構成されていることを特徴とする請求項３に記載の偏向角検出装置。
【０１４３】
（４２）前記第１面が正のパワーを有する面として構成されていることを特徴とする請求項３に記載の偏向角検出装置。
【０１４４】
（４３）前記第１〜第４面が、フレネル面で構成されていることを特徴とする請求項３に記載の偏向角検出装置。
【０１４５】
（４４）請求項１〜３、上記（１）〜（４３）のいずれかに記載の偏向角検出装置を用いた光信号スイッチシステム。
【０１４６】
（４５）請求項１〜３、上記（１）〜（４３）のいずれかに記載の偏向角検出装置と、前記偏向角検出装置からの出力により前記光偏向素子の偏向角を制御する偏向角制御手段とを有することを特徴とする光信号スイッチシステム。
【０１４７】
（４６）請求項１〜３、上記（１）〜（４３）のいずれかに記載の偏向角検出装置を用いた情報記録再生システム。
【０１４８】
（４７）請求項１〜３、上記（１）〜（４３）のいずれかに記載の偏向角検出装置と、光を照射することにより情報信号の記録または再生あるいはその両方が可能な記録面を有する記録媒体と、該記録媒体に前記情報信号を記録または再生あるいはその両方を行う光束を照射する光源と、前記光束を前記記録媒体の記録面に結像する光学系と、該光学系内に配置され、前記光束を前記記録面に平行な面内で偏向し、偏向角に連動して傾斜角が変わる前記検出用反射面を有する前記光偏向素子と備えたことを特徴とする情報記録再生システム。
【０１４９】
（４８）請求項１〜３、上記（１）〜（４３）のいずれかに記載の偏向角検出装置を用いた光を偏向するシステム。
【０１５０】
【発明の効果】
本発明の偏向角検出装置によれば、検出用反射面の角度検出を広範囲に行うことができ、またコンパクトなメカレイアウトを実現した偏向角検出装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の第１実施例に係る偏向角検出装置の概略構成図であり、ミラー回転角が０度の状態を示している。
【図２】本発明の第１実施例に係る偏向角検出装置の概略構成図であり、ミラー回転角がｙｚ面内でｘ軸回りに−１０度回転した状態を示している。
【図３】本発明の第１実施例に係る偏向角検出装置の概略構成図であり、ミラー回転角がｙｚ面内でｘ軸回りに１０度回転した状態を示している。
【図４】本発明の偏向角検出装置における光検出器に採用することができるＰＳＤの概念図である。
【図５】検出用反射面３が１次元方向（Ｘ方向、またはＹ方向）に傾いたときの光検出器５のセンサ受光面６上にスポット７ａが結像された様子を示す説明図である。
【図６】検出用反射面の傾き量と光検出器５の出力との関係を示すグラフである。
【図７】検出用反射面３が２次元方向に傾いたときの光検出器５のセンサ受光面６上にスポット７ｂが結像された様子を示す説明図である。
【図８】分割受光器（４分割ＰＤ）を採用した光検出器５のセンサ受光面６上にスポット７が結像された様子を示す説明図である。
【図９】本発明の第２実施例に係る偏向角検出装置の概略構成図である。
【図１０】本発明の第３実施例に係る偏向角検出装置の概略構成図である。
【図１１】本発明の第４実施例に係る偏向角検出装置の概略構成図である。
【図１２】本発明の第５実施例に係る偏向角検出装置の概略構成図である。
【図１３】図１に示された光路図であるミラー回転角０度の場合の横収差図である。
【図１４】図２に示された光路図の状態（Ｘ軸回りのミラー回転角−１０度）の場合の横収差図である。
【図１５】図３に示された光路図の状態（Ｘ軸回りのミラー回転角１０度）の場合の横収差図である。
【図１６】本発明の偏向角検出装置を用いた光信号スイッチシステム１０６の一例の概略構成を示す説明図である。
【図１７】回動ミラー１５の反射面に直角な断面とそのまわりの構成を示す説明図である。
【図１８】本発明による偏向角検出装置を用いた装置の他の例として、回動ミラー１５を傾斜させて光信号スイッチング制御を行うための偏向角制御手段６１’の制御ブロック図である。
【図１９】本発明による偏向角検出装置を用いた情報記録再生システム１１０の概略構成を示す平面図である。
【符号の説明】
１　　　　　半導体レーザ
１ｂ　　　　レーザ駆動手段
２，２’　　プリズム
２ａ，２’ａ　　　第１面
２ｂ，２’ｂ　　　第２面
２ｃ，２’ｃ　　　第３面
２ｄ，２’ｄ　　　第４面
３　　　　　検出用反射面
４　　　　　偏心レンズ
４ａ　　　　第１面
４ｂ　　　　第２面
５　　　　　光検出器
６　　　　　光検出面（センサ受光面）
７，７ａ，７ｂ　　　　　スポット
８，８ａ，８ｂ，８ｃ，８ｄ　　　　　受光面
１５，１５Ａ，１５Ｂ　　　　　回動ミラー
１５ａ　　偏向ミラー面
１５ｂ　　支持部材
１５ｃ　　検出用反射面
１５ｄ　　アクチュエータ
６０　　　偏向角検出装置
６１’　　偏向角制御手段
６１’ａ　デコード手段
６１’ｂ　制御部
１０１，１０１Ａ　　　　　入力側ケーブル
１０２　　コリメータユニット
１０３、１０３Ａ　　　　　レーザ光束（光信号）
１０５　　出力側ケーブルユニット
１０６　　光信号スイッチシステム
１０７　　結像ユニット
１０８　　光スイッチングデバイス
１０９、１０９Ｂ　　　　出力側ケーブル
１０９ａ　入射口
１１０　　記録情報再生システム
１１１　　筐体
１１２　　記録ディスク
１１２ａ　駆動軸
１１３ａ　回転軸
１１４　　結像レンズユニット
１１５　　レーザ
１１６　　結像レンズ
１１７　　駆動コイル[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a deflection angle detection device and a system including the deflection angle detection device. In particular, the present invention relates to a deflection angle detection device as a tracking detection device used in an optical pickup, an optical switching device of an optical fiber used for optical communication, and a system including the deflection angle detection device.
[0002]
[Prior art]
In recent years, the technology of optical information communication and optical information recording has been remarkably developed, and information transmission density and information recording density have been dramatically increased. In these fields, for example, an optical signal switch that optically switches an optical fiber line at a relay point or a tracking control of an optical pickup of an optical information recording / reproducing system is used to detect the deflection state of an optical deflection mirror element with high accuracy. It is indispensable to improve the technology to control the posture. Therefore, conventionally, various deflection angle detection devices have been proposed.
[0003]
Conventional deflection angle detectors of this type include, for example, Japanese Patent Publication No. 7-66554, Japanese Patent Application Laid-Open No. 8-227552, Japanese Patent Application Laid-Open No. 11-144273, Japanese Patent Application Laid-Open No. 11-114274 and Japanese Patent Application Laid-Open No. 11-114274. There is one described in 195236.
[0004]
A deflection angle detection device described in Japanese Patent Publication No. 7-66554 detects a relative angle between an optical axis of a beam emitted from an optical pickup to a recording medium and a recording surface of the recording medium. This device includes a light emitting element for irradiating a recording surface with diffused light, and two light receiving elements disposed on both sides of the light emitting element and detecting reflected light from the recording surface. Then, this device detects the amount of deflection when the recording medium is deflected by calculating the difference between the amounts of reflected light detected by the two light receiving elements.
[0005]
A deflection angle detector described in Japanese Patent Application Laid-Open No. 8-227552 similarly detects a relative angle between an optical axis of a beam emitted from an optical pickup to a recording medium and a recording surface of the recording medium. It is. In this apparatus, reflected light from a recording medium is received by a light receiving surface divided into four parts, and the amount of deflection in two directions is detected by calculating the difference between the amounts of received light.
[0006]
Further, a deflection angle detection device described in JP-A-11-144273 or JP-A-11-144274 uses a photodetector that reflects reflected light from a deflecting mirror through a beam splitter whose reflectivity changes depending on an incident angle. The amount of deflection is detected by detecting the amount of light.
[0007]
A deflection angle detection device described in Japanese Patent Application Laid-Open No. H11-195236 detects the rotation position of a deflection mirror in an optical information reproducing device, and converts a light beam from a laser light source into a linear light beam on the deflection mirror. By condensing the light, the deflection angle is detected while increasing the measurement accuracy in one direction.
[0008]
[Problems to be solved by the invention]
However, the conventional deflection angle detection device as described above has the following problems.
[0009]
In the deflection angle detection device described in Japanese Patent Publication No. 7-66554, reflected light reciprocating between the head of the optical pickup and the recording medium is detected by the light receiving elements on both sides of the light emitting element. Can only be detected. In order to widen the detection range of the amount of deflection, the distance between the light emitting element and the recording medium must be widened and the light receiving element must be increased, so that a compact deflection angle detecting device cannot be obtained. As described above, the deflection angle detection device has a problem that a wide range of detection cannot be performed because the size of the detector is limited. In addition, since two light receiving elements are used, there is a problem that only one-dimensional inclination can be detected.
[0010]
Further, the deflection angle detection device described in Japanese Patent Application Laid-Open No. 8-227552 can detect a two-dimensional tilt, but if the detection range is to be widened, the distance between the light emitting element and the recording medium is increased, and The device must be large. As described above, in the case of performing detection over a wide range, the size of the detector is increased, and the overall mechanical layout is also increased. As in Japanese Patent Publication No. 7-66554, a compact deflection angle detection device cannot be obtained. There was a problem.
[0011]
Further, in the deflection angle detecting devices described in JP-A-11-144273 and JP-A-11-144274, the characteristics of the reflection film of the beam splitter directly affect the detection accuracy. There is a problem that the detection accuracy is deteriorated if the value is not improved. In addition, since these deflection angle detection devices use a configuration in which the detection light is bent in a U-shape without overlapping, the arrangement area becomes large, and if the detection range is to be expanded, the beam splitter surface of the beam splitter must be changed. It has to be made large, and the whole mechanical layout becomes large, and there is a problem that a compact deflection angle detecting device cannot be obtained.
[0012]
Further, in the deflection angle detecting device described in Japanese Patent Application Laid-Open No. H11-195236, when the detection range is widened, mechanical interference and the entire mechanical layout increase. Further, in this deflection angle detecting device, the deflection angle detection accuracy is improved by using a linear light beam, but this is a means effective only in one-dimensional direction.
[0013]
The present invention has been made in view of such a problem, and it is an object of the present invention to provide a deflection angle detection device that can be configured to be compact even if the optical path length is lengthened and that can widen a deflection angle detection range. .
It is another object of the present invention to provide a deflection angle detection device capable of detecting a deflection angle with high accuracy.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a deflection angle detection device according to the present invention is a deflection angle detection device that detects a deflection angle of a light deflection element, and includes a light source that emits light, and at least one of light emitted from the light source. An optical path conversion surface for switching the optical path of the unit, a reflection surface for detection provided in the light deflector provided on the optical path switched by the optical path conversion surface, and light reflected by the reflection surface for detection. A light detector for detecting a deflection angle of the light deflecting element based on a light receiving position thereof, and at least a transmission surface having a positive power is provided between the reflection surface for detection and the light detector. It is characterized by:
In this specification, the deflection angle of the light deflecting element means the inclination angle of the reflection surface of the light deflecting element.
[0015]
The deflection angle detection device according to the present invention is a deflection angle detection device that detects a deflection angle of a light deflection element, and includes a light source that emits light, a prism having at least three surfaces, and two surfaces. The configured eccentric lens, the reflection surface for detection provided on the light deflector, and the light reflected by the reflection surface for detection, which are arranged on the optical path of the light from the light source switched through the prism. A light detector for detecting the deflection angle of the light deflecting element based on the light receiving position, wherein the prism has a function of transmitting incident light from a light source into the prism, A function of reflecting light transmitted through one surface, a function of transmitting light reflected by another optically active surface of the prism and emitting the light from the prism to the reflection surface for detection, and an incident light from the reflection surface for detection Through the prism A third surface having a function of reflecting light reflected on the second surface toward the reflection surface for detection and a function of transmitting light transmitted through the second surface to the photodetector side; And a fifth surface, wherein the eccentric lens is a transmission surface having a positive power and located between the fourth surface and the photodetector, the fourth surface being opposed to the third surface. And is characterized by the following.
[0016]
A deflection angle detection device according to the present invention is a deflection angle detection device that detects a deflection angle of an optical deflection element, and includes a light source that emits light, a prism including at least four surfaces, and a prism. A reflection surface for detection provided on the light deflecting element, which is disposed on an optical path of light from the light source that has been switched, and receives light reflected by the reflection surface for detection; A light detector for detecting a deflection angle of the element, wherein the prism has a first surface having an effect of transmitting incident light from a light source into the inside of the prism, and a light reflected through the first surface for reflection for detection. A second surface having a function of reflecting light toward the surface and a function of transmitting light transmitted through another optically active surface of the prism and emitting the light from the prism toward the photodetector; Light from the prism A third surface having an operation of emitting light toward the reflection surface for detection; and a fourth surface having an operation of transmitting incident light from the reflection surface for detection into the prism. At least one of the two surfaces has a positive power.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
With the configuration according to the present invention, it is possible to realize a highly accurate and compact deflection angle detection device which has a wide detection range and can detect one-dimensional or two-dimensional directions. In addition, a specific description of the operation and effect will be made in the description of the embodiment described later.
[0018]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Note that the deflection angle detection device according to the present invention detects the deflection angle by irradiating the light deflection element that deflects light with another light. Therefore, the present invention can be applied to various systems including such a light deflecting element.
In the following, the light irradiated to detect the deflection angle will be referred to as detection light in order to distinguish it from the light deflected by the light deflector.
[0019]
Examples of such a light deflecting element include, for example, a galvano mirror in which a mirror for deflecting light is rotatably held by a rotating means such as an electromagnetic coil, and a plurality of mirror surfaces for deflecting light. There are a rotary polygon mirror attached to a motor shaft, a movable mirror that changes the installation angle by holding a mirror for deflecting light with an actuator, and an element that movably provides a prism or hologram for deflecting light.
[0020]
Examples of a system including such an optical deflection element include an optical signal switch system and an information recording / reproducing system (optical information recording / reproducing system).
[0021]
Hereinafter, an embodiment of the deflection angle detecting device of the present invention will be described, and further, a configuration example of an optical signal switch system and an information recording / reproducing system using the deflection angle detecting device of the present invention will be described.
[0022]
A deflection angle detection device according to an embodiment of the present invention will be described.
First embodiment
1 to 3 are schematic configuration diagrams of a deflection angle detecting device according to a first embodiment of the present invention. FIG. 1 shows a state in which the mirror rotation angle is 0 degrees, and FIG. 2 shows a state in which the mirror rotation angle is x in the yz plane. FIG. 3 shows a state in which the mirror is rotated by −10 degrees around the axis, and FIG. 3 shows a state in which the mirror is rotated by 10 degrees around the x axis in the yz plane. In the xyz coordinate system shown in the figure, the x direction is a direction perpendicular to the paper surface, the y direction and the z direction are in a plane parallel to the paper surface, the y direction is the upper side of the drawing, and the z direction is the right side of the drawing, respectively. This is a rectangular coordinate system that assumes a positive direction. Arrows in the drawing indicate the inclination direction of the reflection surface for detection. This coordinate system is common to each embodiment described later. The rotation direction is positive in the counterclockwise direction.
[0023]
The deflection angle detection device according to the present embodiment includes a light source, a cover glass, a prism 2, a reflection surface 3 for detection, an eccentric lens 4, and a photodetector 5.
The light source is a semiconductor laser 1 (semiconductor laser element) that emits a laser beam (detection light) toward a detection reflection surface 3 provided in the light deflection element.
Note that any semiconductor laser may be used as the semiconductor laser 1, but it is natural that a laser having an appropriate wavelength is selected from the relationship with the detection sensitivity of the photodetector 5. Further, although any known means may be used, it is needless to say that the semiconductor laser 1 is connected to a driving means including a power supply and a modulation driving circuit for appropriately emitting light, although not shown.
[0024]
The prism 2 and the eccentric lens 4 are arranged between the reflection surface 3 for detection and the photodetector 5.
The prism 2 is configured to have three optically active surfaces of a first surface 2a, a second surface 2b, and a third surface 2c.
The first surface 2a is an incident surface having a function of transmitting a laser beam from a light source into the prism. The first surface 2a has a positive power. The second surface 2b is formed as an aspheric surface having a positive power, and faces the reflection surface 3 for detection. In addition, the second surface 2b detects a light reflected by the third surface 2c and a reflecting surface having an action of totally reflecting light transmitted through the first surface 2a toward the third surface 2c according to the portion. It has both an exit surface having an operation of transmitting light toward the reflection surface 3 for use and an incident surface having an operation of transmitting light reflected by the reflection surface 3 for detection into the prism. The third surface 2c includes an optical path conversion surface that reflects a part of the light flux from the light source totally reflected by the second surface 2b and switches the optical path in the direction of the detection reflection surface 3 according to the portion, and a second surface 2b. It also serves as an exit surface having the function of transmitting the transmitted light beam from the detecting reflection surface 3 to the photodetector 5 side. The third surface 2c is formed as a free-form surface having a positive power.
[0025]
The eccentric lens 4 is arranged between the prism 2 and the photodetector 5 and is joined to the prism 2. The eccentric lens 4 has two optically active surfaces, a first surface 4a (corresponding to the fourth surface of the present invention) and a second surface 4b (corresponding to the fifth surface of the present invention). .
The first surface 4a is a free-form surface, is joined to the surface 2c of the prism 3 using a UV curable resin or the like, and is an incident surface having a function of transmitting light emitted from the surface 2c of the prism 2. . The second surface 4b is formed as a free-form surface having a positive power, and is an exit surface having an operation of transmitting a light beam transmitted through the surface 4a.
[0026]
The prism 2 and the eccentric lens 4 are made of a medium having a refractive index of 1 or more, for example, glass such as OHARA S-BSL7 or optical plastic such as amorphous polyolefin as a glass material.
The prism 2 and the eccentric lens 4 may be formed of a medium having a refractive index of 1 or more, and a structure in which the inside of the surface formed of the glass material is hollow or filled with a liquid is also applicable.
The surface 2c is coated with a polarizing film that transmits one linearly polarized light component (here, P-polarized light) and reflects the other linearly polarized light component (here, S-polarized light) among the orthogonally polarized light components. Polarization beam splitter surface. The prism 2 and the eccentric lens 4 constitute one polarization beam splitter.
Although not shown, a 波長 wavelength plate is disposed between the surface 2 b and the reflection surface 3 for detection.
[0027]
The photodetector 5 is arranged on the optical axis transmitted through the polarization beam splitter surface 2c. Reference numeral 6 denotes a sensor light receiving surface of the photodetector 5.
The light detector 5 outputs a voltage corresponding to the center position of the light intensity of the spot when the spot of the laser beam is irradiated on the sensor light receiving surface 6 to detect the position of the spot. A device (Position \ Sensitive \ Detector, so-called PSD) can be adopted. The PSD is configured by arranging a large number of photodiodes. For example, as shown in FIG. 4, when a predetermined portion is irradiated with a light beam, the corners of the PSD are transmitted from four terminals T1, T2, T3, and T4. Voltages corresponding to the distances D1, D2, D3, and D4 from the unit to the center of gravity of the light beam are output, and by calculating this output value, position detection (inclination in the X and Y directions) is performed. .
As the photodetector 5, one-dimensional or two-dimensional position detection is performed according to whether the direction of inclination of the detecting reflecting surface 3 is one-dimensional (X direction or Y direction) or two-dimensional (X direction and Y direction). Adopt what does. It is needless to say that the photodetector 5 includes a power supply and appropriate driving means for its operation. However, since it is well known, the description thereof is omitted.
[0028]
In the thus-configured deflection angle detecting device according to the present embodiment, as shown in FIGS. 1 to 3, the laser light emitted from the semiconductor laser 1 as the light source passes through the cover glass and passes through the positive power of the prism 2. Is transmitted through the first surface 2a having an angle and enters the second surface 2b. Next, the light is totally reflected by being incident on the second surface 2b at a critical angle or more, and then the S-polarized light is reflected by the polarization beam splitter surface 2c and is incident again on the second surface 2b. The incident light passes through the second surface 2b, passes through a quarter-wave plate (not shown), becomes circularly polarized light, enters the detection reflection surface 3, and is reflected. The light reflected by the reflection surface 3 for detection passes through a quarter-wave plate (not shown) again to become P-polarized light. Next, the light again passes through the second surface 2b of the prism 2 and again enters the beam splitter surface 2c. Then, the light transmitted through the beam splitter surface 2c and the first surface 4a of the eccentric lens 4 is incident on the inside of the eccentric lens 4, and transmitted through the second surface 4b having a positive power. Is emitted. The light emitted from the eccentric lens 4 enters the photodetector 5 to form a light spot.
[0029]
The photodetector 5 detects the amount of tilt by detecting the position of a spot on the sensor light receiving surface 6 when the detecting reflecting surface 3 is tilted in the X and Y directions.
FIG. 5 is an explanatory diagram showing a state in which a spot 7a is formed on the sensor light receiving surface 6 of the photodetector 5 when the detection reflecting surface 3 is inclined in a one-dimensional direction (X direction or Y direction). . FIG. 6 is a graph showing the relationship between the amount of inclination of the reflection surface for detection 3 and the output of the photodetector 5.
[0030]
When the reflecting surface for detection 3 is inclined in the one-dimensional direction, the position of the spot 7a on the light receiving surface 6 of the photodetector 5 moves. At this time, the output of the photodetector 5 changes almost linearly as shown in the graph of FIG. FIG. 7 is an explanatory view showing a state in which a spot 7b is formed on the sensor light receiving surface 6 of the photodetector 5 when the detecting reflection surface 3 is inclined in the two-dimensional direction. When the reflecting surface 3 for detection moves in the X and Y directions, the spot 7b on the light receiving surface 6 moves in a two-dimensional direction. At this time, the outputs in the respective directions are similarly as shown in the graph of FIG. 6, and the inclination amount (angle) of the reflection surface for detection 3 and the output are improved in linearity. In the configuration of the present embodiment, it is possible to detect the inclination of the detection reflecting surface 3 in a range of about ± 10 degrees.
Therefore, with the configuration of the present embodiment, it becomes possible to use the optical pickup as an optical path switching, which needs to detect a wide range of the inclination of the detecting reflection surface, as a tracking unit, and as an optical switching unit for optical communication.
[0031]
In the embodiment of the present invention, it is also possible to detect the deflection angle by employing a four-division light receiver (four-division PD) instead of the position detection light detector (PSD) as the light detector.
FIG. 8 is an explanatory diagram showing a state in which a spot 7 is formed on the sensor light receiving surface 6 of the photodetector 5 employing the four-division light receiver (four-division PD).
The spot diameter of the laser light A focused on the photodetector 5 employing the four-division light receiver (four-division PD) is made larger than the spot diameter of the laser light focused on the photodetector employing the ordinary PSD. Has been done. The light receiving surface 8 of the photodetector 5 is divided into four light receiving surfaces (8a, 8b, 8c, and 8d, respectively). When the reflecting surface for detection 3 is inclined two-dimensionally in the X and Y directions, the spot 7 on the light receiving surface 8 moves in the two-dimensional direction. At this time, assuming that outputs corresponding to the areas irradiated on the light receiving surfaces 8a, 8b, 8c, and 8d are A, B, C, and D, respectively, the output corresponding to the position in the X direction is (A + D−B−C). / (A + B + C + D) and the output corresponding to the position in the Y direction are obtained by calculating (A + BCD) / (A + B + C + D), respectively. The calculation output in each direction changes almost linearly as long as the spot shape is uniform.
[0032]
According to the deflection angle detecting device of the present embodiment configured as described above, there are the following advantages.
In the deflection angle detecting device of the present embodiment, since the first surface 2a of the prism 2 has a positive power, the height of the marginal ray of the light emitted from the light source is reduced, and the light flux is reduced. For this reason, the F-number becomes small, and the occurrence of aberration can be suppressed. In addition, since the free-form surface is provided in the optical path before and after the reflection surface for detection, it is possible to correct aberrations of off-axis rays such as field curvature and distortion caused by rotation of the reflection surface for detection. By these, the change in the spot diameter at the central portion and the peripheral portion of the light beam to the photodetector due to the rotation angle of the detection reflection surface is reduced, and the rotation angle of the detection reflection surface and the light beam on the photodetector are reduced. The linearity of the position can be further ensured, and the deflection angle can be detected with high accuracy.
[0033]
Further, in the deflection angle detecting device according to the present embodiment, the second surface 2b of the prism 2 has a reflection angle equal to or larger than the critical angle so that light incident from the first surface 2a of the prism 2 is totally reflected. Therefore, the loss of light quantity can be minimized. Since the second surface 2b does not need to be coated with a reflective film, the cost can be reduced accordingly.
Further, the second surface 2b is a surface that emits light from the prism 2 toward the reflection surface 3 for detection, and a surface that enters the light reflected by the reflection surface 3 for detection into the prism 2 and is one of the surfaces. The surface can share the above-described total reflection surface and transmission surface. Therefore, the optical working surface can be used efficiently, and the cost can be reduced accordingly.
[0034]
In the deflection angle detecting device of the present embodiment, the third surface 2c of the prism 2 is a surface having a positive power, and has an effect of making light from the light source substantially parallel in the optical system up to the reflection surface for detection. Have. The surface 2c is coated with a film so as to function as a polarizing beam splitter, reflects S-polarized light from a light source, and has a 波長 wavelength plate (not shown), a reflecting surface for detection, The P-polarized light that has entered the prism 2 again through the wave plate (not shown) is transmitted. With this configuration, although the third surface 2c has two functions of reflection and transmission, the loss of light quantity on this surface can be made very small.
[0035]
Further, in the deflection angle detecting device of the present embodiment, the first surface 4a of the eccentric lens 4 has substantially the same shape as the third surface 2c of the prism 2 and is bonded using a UV curing resin or the like. There is theoretically no interface between the third surface 2c and the first surface 4a of the eccentric lens 4, and loss of light quantity can be reduced. When the light enters the eccentric lens 4 from the prism 2, there is almost no power.
[0036]
Further, in the deflection angle detecting device of the present embodiment, the second surface 4b of the eccentric lens 4 is a transmitting surface having a positive power, so that in the optical system after being reflected by the detecting reflecting surface 3, this surface 4b With this power, the light can be focused on the detection surface of the photodetector 5.
When the reflection surface for detection is rotated, the reflection point has an angle of view twice the rotation angle as an entrance pupil. For this reason, if the surface 4b is a spherical surface, it is difficult to correct the aberration of off-axis rays. In this embodiment, since the surface 4b is a free-form surface, it is easy to correct the aberration of off-axis rays.
[0037]
In the deflection angle detection device of the present embodiment, the optical system such as the prism 2 and the eccentric lens 4 and the photodetector 5 are arranged on the side facing the reflection surface 3 for detection. Thus, the entire apparatus can be made compact.
[0038]
Second embodiment
FIG. 9 is a schematic configuration diagram of a deflection angle detecting device according to a second embodiment of the present invention.
In the deflection angle detecting device of the present embodiment, the second surface 4b of the eccentric lens 4 is formed on a Fresnel surface having a positive power. Other configurations are almost the same as those of the first embodiment.
According to the deflection angle detecting device of the present embodiment, since the second surface 4b of the eccentric lens 4 is formed on the Fresnel surface, this surface can be formed in a flat plate shape, compared with the polarization angle detecting device of the first embodiment. Therefore, the layout of the entire apparatus becomes easy. Other functions and effects are almost the same as those of the first embodiment.
[0039]
Third embodiment
FIG. 10 is a schematic configuration diagram of a deflection angle detection device according to a third embodiment of the present invention.
In the deflection angle detecting device of the present embodiment, the first surface 2a of the prism 2 is formed on a Fresnel surface, and the second surface 2b, the third surface 2c, and the first surface 4a of the eccentric lens 4 are formed on a plane. The second surface 4b of the eccentric lens 4 is formed as a spherical surface. Further, the reflection surface for detection 3 is formed in a spherical shape. Other configurations are almost the same as the first embodiment.
According to the deflection angle detection device of the present embodiment, the prism 2 is a triangular prism having only one Fresnel surface, and the eccentric lens 4 also has a simple shape of a flat surface and a spherical surface. In comparison, the production becomes easier and the cost can be reduced accordingly.
Further, since the joining surface between the prism 2 and the eccentric lens 4 is a flat surface, the joining process is facilitated, which is advantageous in terms of performance and cost.
[0040]
In addition, the deflection angle detection device according to the present embodiment has the following functions and effects similar to those of the first embodiment in the following points.
In the deflection angle detecting device of the present embodiment, as in the first embodiment, since the first surface 2a of the prism 2 has a positive power, the height of the marginal ray of the light emitted from the light source is reduced, and Becomes smaller. For this reason, the F-number becomes small, and the occurrence of aberration can be suppressed.
[0041]
Further, in the deflection angle detecting device of the present embodiment, similarly to the first embodiment, the critical angle is set so that the light incident inside the prism 2 from the first surface 2a is totally reflected by the second surface 2b of the prism 2. Since the reflection angle is larger than the angle, the loss of the light amount can be minimized. Since the second surface 2b does not need to be coated with a reflective film, the cost can be reduced accordingly.
Further, the second surface 2b is a surface that emits light from the prism 2 toward the reflection surface 3 for detection, and a surface that enters the light reflected by the reflection surface 3 for detection into the prism 2 and is one of the surfaces. The surface can share the above-described total reflection surface and transmission surface. Therefore, the optical working surface can be used efficiently, and the cost can be reduced accordingly.
[0042]
Further, in the deflection angle detecting device according to the present embodiment, similarly to the first embodiment, the third surface 2c of the prism 2 is coated with a film so as to function as a polarizing beam splitter. Is reflected, passes through a quarter-wave plate (not shown), a reflection surface for detection, and a quarter-wave plate (not shown), and transmits the P-polarized light that has entered the prism 2 again. With this configuration, although the third surface 2c has two functions of reflection and transmission, the loss of light quantity on this surface can be made very small.
[0043]
Further, in the deflection angle detecting device of the present embodiment, similarly to the first embodiment, the first surface 4a of the eccentric lens 4 has substantially the same shape as the third surface 2c of the prism 2, and is made of a UV curable resin or the like. Since they are bonded together, the third surface 2c of the prism 2 and the first surface 4a of the eccentric lens 4 theoretically have no interface, and the loss of light amount can be reduced. When the light enters the eccentric lens 4 from the prism 2, there is almost no power.
[0044]
Further, in the deflection angle detecting device of the present embodiment, similarly to the first embodiment, the second surface 4b of the eccentric lens 4 is a transmission surface having a positive power, so that the light is reflected by the detection reflection surface 3. In the optical system, the light can be converged on the detection surface of the photodetector 5 by the power of the surface 4b.
[0045]
Further, in the deflection angle detecting device of this embodiment, as in the first embodiment, the optical system such as the prism 2, the eccentric lens 4, and the photodetector 5 are arranged on the side facing the reflecting surface 3 for detection. The entire system can be made compact by configuring the electric system collectively.
[0046]
Fourth embodiment
FIG. 11 is a schematic configuration diagram of a deflection angle detecting device according to a fourth embodiment of the present invention.
In the deflection angle detection device of the present embodiment, the reflection surface for detection 3 is formed on a Fresnel surface, and the second surface 4b of the eccentric lens 4 is formed on a free-form surface. Other configurations are almost the same as those of the third embodiment.
According to the polarization angle detection device of the present embodiment, the reflection surface for detection has a plate shape, and the layout of the entire device is easier than that of the polarization angle detection device of the third embodiment. Further, since the free-form surface is arranged in the optical path before and after the detecting reflection surface, the deflection angle can be detected with high accuracy as in the first embodiment. Other functions and effects are almost the same as those of the third embodiment.
[0047]
Fifth embodiment
FIG. 12 is a schematic configuration diagram of a deflection angle detecting device according to a fifth embodiment of the present invention.
The deflection angle detection device according to the present embodiment includes a light source, a cover glass, a prism 2 ′, a reflection surface 3 for detection, and a photodetector 5. It also functions as the prism 2 and the eccentric lens 4 in the fourth embodiment.
The prism 2 'has four optically active surfaces, that is, a first surface 2'a, a second surface 2'b, a third surface 2'c, and a fourth surface 2'd. The first surface 2'a is formed as a curved surface having a positive power. The second surface 2'b to the fourth surface 2'd are formed as free-form surfaces having positive power. In the polarization angle detecting device of the present embodiment, no optically active surface of the prism 2 'is coated with a polarizing film. Also, no quarter-wave plate is provided. In addition, the configuration of the light source 1, the cover glass, the reflection surface 3 for detection, and the five light detectors is almost the same as that of the first embodiment.
[0048]
In the thus-configured polarization angle detecting device of the present embodiment, the laser light emitted from the semiconductor laser 1 as the light source passes through the cover glass and passes through the first surface 2′a having the positive power of the prism 2 ′. The light passes through and enters the second surface 2′b. Next, the light is incident on the second surface 2'b at a critical angle or more and totally reflected, exits from the third surface 2'c, enters the detection reflecting surface 3, and is reflected. The light reflected by the reflection surface 3 for detection transmits through the fourth surface 2′d of the prism 2 ′, enters the inside of the prism 2 ′ again, and transmits through the second surface 2′b. Is emitted. The light emitted from the prism 2 'enters the photodetector 5 to form a light spot.
[0049]
According to the deflection angle detecting device of the present embodiment configured as described above, there are the following advantages.
In the deflection angle detecting device of the present embodiment, since the first surface 2'a of the prism 2 'has a positive power, the height of the marginal ray of the light emitted from the light source decreases, and the light flux decreases. For this reason, the F-number becomes small, and the occurrence of aberration can be suppressed. Further, since the free-form surface is arranged in the optical path before and after the detecting reflection surface, the deflection angle can be detected with high accuracy as in the first embodiment.
[0050]
Further, in the deflection angle detection device of the present embodiment, the second angle 2′b of the prism 2 ′ is equal to or larger than the critical angle so that light incident from the first surface 2′a of the prism 2 ′ is totally reflected. , The loss of light quantity can be minimized. Since the second surface 2'b does not need to be coated with a reflective film, the cost can be reduced accordingly.
Further, the second surface 2 ′ b is a surface for emitting the light reflected by the detecting reflection surface 3 and entering the prism 2 ′ toward the photodetector 5. And the transmission surface can be shared. Therefore, the optical working surface can be used efficiently, and the cost can be reduced accordingly.
[0051]
Further, in the deflection angle detection device of the present embodiment, the second surface 2′b and the fourth surface 2′d of the prism 2 ′ having positive power have the same operation as one positive lens, Light can be collected on the detection surface of the photodetector 5 by the power of these surfaces.
Further, the reflection surface for detection has an angle of view twice the rotation angle of the reflection surface for detection as an entrance pupil. Therefore, if the optical system has a wide angle of view and the second surface 2'b and the fourth surface 2'd are spherical, it is difficult to correct off-axis ray aberrations such as image surface distortion and distortion. In the present embodiment, since the second surface 2'b and the fourth surface 2'd are free-form surfaces, aberrations of off-axis rays such as image surface distortion and distortion are corrected.
[0052]
In the first to fourth embodiments, the third surface 2c of the prism 2 is a polarizing beam splitter surface, but may be a half mirror surface. In this case, there is one transmission and one reflection, and the amount of light of the laser light from the light source finally reaching the photodetector 5 is reduced by about 50% during the transmission and the reflection, respectively. Is about 1/4.
Further, the third surface 2c of the prism 2 may be a diffractive optical element or a HOE (holographic optical element).
In addition, a PSD, a two-division, a four-division PD, or the like can be considered as a photodetector. When a predetermined spot size of light is required depending on the detection sensitivity, the photodetector is moved from the focal plane toward the optical axis. The spot size can be adjusted by moving.
[0053]
13 to 17 show the lateral aberration of the first embodiment. In these lateral aberration diagrams, FIG. 13 shows the lateral aberration when the mirror rotation angle is 0 degree, which is the optical path diagram shown in FIG. 1, and FIG. 14 shows the state of the optical path diagram shown in FIG. 2 (mirror around the X axis). FIG. 15 illustrates the lateral aberration in the case of the state of the optical path diagram shown in FIG. 3 (the mirror rotation angle about the X-axis is 10 degrees) in the case of (rotation angle −10 degrees).
Next, the configuration parameters of the optical system constituting the deflection angle detecting devices of the first to fifth embodiments will be shown as numerical data.
In each numerical data, "FFS" is a free-form surface.
The aspherical surface in each embodiment is a rotationally symmetric aspherical surface given by the following definition expression.
Z = (y²/ R) / [1+ ｛1- (1 + k) y²/ R²｝^1/2] + Ay⁴+ By⁶+ Cy⁸+ Dy¹⁰+ ……
Here, Z is an optical axis (on-axis principal ray) where the traveling direction of light is positive, and y is a direction perpendicular to the optical axis. Here, R is a paraxial radius of curvature, k is a conic constant, and a, b, c, d,... Are fourth-, sixth-, eighth-, and tenth-order aspherical coefficients, respectively. The Z axis of this definition expression is the axis of the rotationally symmetric aspherical surface.
[0054]
The free-form surface in each embodiment is represented by the following equation. Note that the Z axis of this equation is the axis of the free-form surface.

However, the first term in the above equation is a spherical term, and the second term is a free-form surface term. In the spherical term, c is the curvature of the vertex, k is the conic constant (cone constant), and r = (X2 + Y2)^1/2It is.
The free-form surface term can be expanded as follows: Here, Cj (j is an integer of 2 or more) is a coefficient.

Note that a term relating to an aspheric surface for which no data is described is zero.
Also, the refractive index is shown for the d-line (wavelength: 587.56 nm).
The unit of the length is mm.
[0055]
Further, in the numerical data of each embodiment, the distance from the reflecting surface for detection to the reflecting surface of the later-described rotating mirror 15 is set to 0 in consideration of design convenience, and the rotation axis is set at the optical axis position of the detecting reflecting surface. It is assumed that there is.
Actually, there is a predetermined distance between the reflection surface for detection and the reflection surface of the rotation mirror 15 described later. However, by providing a rotation axis on the reflection surface for detection, the rotation is made by rotation. Although the position of the reflecting surface of the mirror 15 is shifted, the position can be corrected by electrically controlling the rotation angle. Does not affect the essence of the invention.
Also, the diaphragm surface in each numerical data below is a virtual diaphragm surface, and does not indicate that there is actually a diaphragm there. Further, a flare stop for removing harmful light can be provided between each plane as needed.
[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]
Next, an example of a system using the deflection angle detection device of the present invention described using the above embodiment will be described.
FIG. 16 is an explanatory diagram showing a schematic configuration of an example of the optical signal switch system 106 using the deflection angle detecting device of the present invention.
This system is based on an input side where an optical transmission cable such as an optical fiber cable into which a laser beam 103... (Optical signal) whose intensity, pulse width, frequency, etc. are modulated according to an information signal is transmitted. A cable unit 100, an output cable unit 105 for bundling an optical transmission cable such as an optical fiber cable and transmitting a laser beam 103... Inside, and a laser beam 103 provided between these units are selectively provided. It comprises optical switching devices 108, 108 for deflecting light.
[0072]
The input side cable unit 100 emits the laser beam 103 transmitted inside to the outside at the end of an optical transmission cable composed of, for example, an optical fiber cable in which a spun glass fiber is protectively coated with plastic. A plurality of input-side cables 101 each having an opening 101a are bundled. A collimator unit 102 that functions to convert the laser beam 103 into a parallel beam is disposed on the optical axis of each emission port 101a. In the input-side cable 101, the emission ports 101a are aligned in the emission direction, and are arranged regularly at predetermined intervals. The emission ports 101a are arranged in a lattice matrix of, for example, 2 × 2, 64 × 64, etc. according to the number.
[0073]
Similarly, the output side cable unit 105 is formed by bundling a plurality of output side cables 109 each having an entrance 109a through which the laser beam 103 is incident at the end of the optical transmission cable. An imaging unit 107 that functions to form an image of the laser beam 103 is disposed on the optical axis of each of the entrances 109a. In the output-side cable 109, the incident ports 109a are aligned in the incident direction, and are arranged regularly at predetermined intervals. The entrances 109a are arranged in a lattice matrix of, for example, 2 × 2, 64 × 64, etc. according to the number.
[0074]
In the input side cable unit 100 and the output side cable unit 105, an optical switching device 108 is disposed in the direction in which the laser beam 103 enters and exits. The optical switching device 108 includes a rotating mirror 15 (optical deflecting element) that can be independently tilted one-dimensionally or two-dimensionally, and a tilt angle (deflection angle) from a neutral position of the present invention. And deflection angle control means 61 'for controlling the deflection angle of the rotating mirrors 15 based on the output from the deflection angle detection device 60.
[0075]
The optical switching devices 108, 108 are arranged such that their rotating mirrors 15 correspond to the outgoing ports 101a and the entrance ports 109a, respectively, and the rotating mirrors 15 are tilted to the neutral position. Thus, the laser beam 103 emitted from the predetermined exit port 101a is arranged so as to be reflected by the respective rotating mirrors 15, 15 and enter the predetermined entrance port 109a.
[0076]
FIG. 17 is an explanatory diagram showing a cross section perpendicular to the reflection surface of the rotating mirror 15 and a configuration around it.
The turning mirror 15 in FIG. 17 is an example in which a galvano mirror is adopted. For example, by embedding a surface reflection plane mirror on the front and back surfaces of a plate-shaped support member 15b supported so that the tilt angle can be arbitrarily adjusted by a well-known actuator 15d such as an electromagnetic coil, the surface side of the support member 15b A deflecting mirror surface 15a for reflecting the laser beam 103 is formed on the back side of the support member 15b, and a detecting reflection surface 15c is formed on the back surface side.
In the present invention, as described above, a rotation axis may be provided on the surface of the detection reflection surface 15c to electrically correct an error due to a positional shift of the deflecting mirror surface 15a. , 15c) may be provided with a rotation axis, and the two surfaces may be rotated at the same rotation angle via a link mechanism or the like.
[0077]
The deflecting mirror surface 15a and the detecting reflecting surface 15c need not be parallel, but are joined so that the detecting reflecting surface 15c is inclined in accordance with the deflection angle of the deflecting mirror surface 15a. In the illustrated example, the deflecting mirror surface 15a and the detecting reflection surface 15c are each fixed to the support member 15b. Therefore, the deflecting mirror surface 15a and the reflection surface for detection 15c share the center of rotation. The surface accuracy and the reflectance are set individually so as to be appropriate for the detection light and the laser beam 103 to be reflected appropriately.
[0078]
The rotating mirror 15 has a deflecting mirror surface 15a arranged in a direction in which the laser beam 103 enters, and a reflecting angle detecting device 60 for detecting a deflection angle is provided on a detecting reflecting surface 15c on the rear side. They are provided to face each other.
[0079]
The deflection angle control means 61 'receives the rotation mirror 15, a deflection angle control signal 201 for specifying the deflection angle thereof, and a power supply voltage 200 from outside, and is electrically connected to the actuator 15d and the deflection angle detection device 60, respectively. It is configured to output a drive signal 202 for driving 15 d and to input a detection level signal 203 from a deflection angle detection device 60 that detects the deflection angle of the rotating mirror 15.
[0080]
In the optical signal switch system 106 configured as described above, first, in a normal transmission line relay state, the laser beam 103 transmitted inside the one input side cable 101 is emitted in a regular array in a lattice matrix. Reaches one of the ports 101a, and is radiated to the outside of the input side cable 101 therefrom. Then, the emitted light is condensed by the collimator unit 102, and is converted into a parallel beam having an appropriate thickness so as not to be shaken by dust or the like, and is emitted toward the optical switching device 108.
[0081]
Here, the rotating mirrors 15 at the neutral position, which are provided at the subsequent stages of the collimator units 102, respectively convert the specific laser beam 103 into the specific rotating mirror at the neutral position of the other optical switching device 108. 15 and is incident on one of the imaging units 107 corresponding to the specific entrances 109a of the output side cable units 105 arranged regularly. Then, the laser beam 103 is transmitted through the incident imaging unit 107, is imaged on the entrance 109 a of the predetermined optical cable 101 in the output side cable unit 105, and the laser beam 103 enters the inside and is transmitted.
[0082]
In the optical signal switch system 106 according to this embodiment, the rotation mirrors 15 and 15 are tilted from the neutral position by a predetermined deflection angle to change the arrival position of the laser beam 103. For example, in FIG. 14, when the laser beam 103A emitted from the specific input side cable 101A is switched from the normal relay state to the output side cable 109B, first, the deflection angle of the rotating mirror 15A is changed to change the laser beam 103A. Is deflected toward the turning mirror 15B. In a normal relay state, the rotating mirror 15B causes another laser beam 103 to enter the output side cable 109B at the neutral position. In this case, the laser beam 103A corresponds to the incident angle of the laser beam 103A. The deflection angle of the rotating mirror 15B is changed so as to be incident on the mirror.
[0083]
The exit ports 101a and the entrance ports 109a are regularly arranged, so that the deflection angles of the rotating mirrors 15 and 15 corresponding to the exit ports 101a and the entrance ports 109a are determined by the positional relationship between the optical switching devices 108 and 108. Is predetermined in advance. Therefore, the optical signal switching can be performed by inclining the specific rotating mirrors 15 and 15 to a predetermined deflection angle.
Therefore, the deflection angles of the rotation mirrors 15 and 15 are detected by the above-described deflection angle detection device 60, and the feedback control of the actuator 15d is performed via the deflection angle control means 61 'shown in FIG.
[0084]
Next, as another example of the device using the deflection angle detecting device according to the present invention, a deflection angle control means 61 'for tilting the rotating mirror 15 and performing optical signal switching control will be described. FIG. 18 is a control block diagram thereof.
More specifically, the deflection angle control means 61 'decodes a deflection angle control signal 201 specifying the deflection angle, and generates a target level signal 204 corresponding to the target deflection angle of the rotating mirror 15; The control unit 61'b receives a deviation between the detection level signal 203 from the deflection angle detection device 60 and the target level signal 204 and generates a drive signal 202 for the actuator 5d.
[0085]
Next, an optical signal switching method will be described mainly with reference to FIGS.
First, the input cable 101A and the output cable 109B of the switching laser beam 103A are specified. Each piece of information is externally input to the deflection angle control means 61 'of each optical switching device 108 by the deflection angle control signal 201, and is input to the decoding means 61'a.
[0086]
The decoding means 61'a generates a target level signal 204 corresponding to the target deflection angle of the rotating mirror 15. The deviation of the target level signal 204 from the detection level signal 203 due to the detected deflection angle is input to the control unit 61'b. The controller 61'b amplifies, differentiates, integrates, or the like the deviation, adjusts the drive signal 202 so that the deflection angle of the rotating mirror 15 approaches the target deflection angle, and feeds it back to the actuator 15d for output. I do.
[0087]
As described above, since the feedback control is performed using the deflection angle detection device 60 as the detection means, the deflection angle of the rotating mirror 15 is corrected to the target deflection angle. Therefore, for example, even if a disturbance occurs and the deflection angle deviates from the target deflection angle, the deflection angle is immediately corrected to the target deflection angle according to the deviation amount. That is, real-time feedback control is realized by the optical switching device 108 including the deflection angle control unit 61 'and the deflection angle detection device 60.
[0088]
Furthermore, since the deflection angle detection device 60 of the present invention is configured to be compact, the optical switching device 108 can be reduced in size and space. In addition, since the deflection angle detecting devices 60 arranged behind the rotating mirrors 15 are compact, the arrangement interval of the rotating mirrors 15 can be narrowed. Therefore, the input side cable unit 100 and the output side cable unit The arrangement intervals of the optical cables 101... Can be increased and the optical cables 101 can be made compact. As a result, there is an advantage that the number of switchable transmission paths can be increased without increasing the deflection angle of the rotating mirror 15.
[0089]
Such an effect is made possible by the feature of the present invention that the optical path is condensed and condensed by using a concave reflecting surface which has not been adopted in the conventional optical signal switching system.
[0090]
In the above description, an example has been described in which one rotating mirror 15 is provided for each of the emission ports 101a of the input side cable unit 100. However, there are other uses for switching the transmission path than those for individually switching the laser beam 103. For example, this is a case in which a line is switched to a backup line during maintenance of a transmission line. In this case, the entirety of the predetermined input side cable unit 100 is switched from one output side cable unit 105 to another output side cable unit 105. In such a case, the switching is performed while maintaining the arrangement of the input side cable units 100 as it is, so that one rotating mirror 15 may be provided for the input side cable units 100.
[0091]
Next, an example of an information recording / reproducing system such as a pickup device provided with the deflection angle detecting device of the present invention will be described. FIG. 19 is a plan view showing a schematic configuration of an information recording / reproducing system 110 using the deflection angle detecting device according to the present invention.
[0092]
This system includes a recording disk 112 (recording medium) such as an optical disk or a magneto-optical disk for recording and reproducing an information signal, and a laser beam 115 (light beam) whose intensity and pulse width are modulated according to the information signal. ), An imaging lens 116 and an imaging lens unit 114 that form an image of the laser beam 115, and a laser beam 115 that is deflected to change the incident position on the imaging lens unit 114. An optical system including a rotating mirror 15 deflectably driven by an actuator (not shown) for performing fine movement tracking control, a deflection angle detection device 60 of the present invention, and recording of the recording disk 112 by installing these optical systems. An arm 113 that can be moved in a direction parallel to the surface and in a direction perpendicular to the surface.
The semiconductor laser 1 is connected to laser driving means 1b for modulating the semiconductor laser 1 with an information signal.
The configuration shown in FIG. 17 can be adopted for the rotating mirror 15. The deflection angle detection device 60 can employ any of the above-described embodiments.
[0093]
Reference numeral 111 denotes a housing, in which a recording disk 112 is disposed on a drive shaft 112a that is driven to rotate by, for example, a DC control motor. The recording disk 112 is held rotatably around the drive shaft 112a.
[0094]
The recording disk 112 has a recording surface on at least one of its surfaces, on which one or both of optical signal recording and reproduction is possible. On the formatted recording disk 112, track signals are formed in the circumferential direction of the recording surface, and the recording position of the information signal is logically divided in the radial direction.
[0095]
The arm 113 is disposed above the recording surface, and is elastically supported vertically with respect to the recording disk 112. The arm 113 is rotatably supported by a rotating shaft 113a in a direction parallel to the recording surface of the recording disk 112, and is rotatable about the rotating shaft 113a by a driving coil 117 such as an electromagnetic coil.
[0096]
The imaging lens 116 is configured to appropriately shape the laser beam 115 emitted from the semiconductor laser 1 into, for example, a parallel beam. The imaging lens unit 114 receives the laser beam 115 to form an image on a recording surface, receives reflected light from the recording surface, and outputs signal light corresponding to an information signal and focus detection for performing focus control. Each of the light receiving elements receives light and tracking detection light for performing tracking control.
[0097]
Between the imaging lens 116 and the imaging lens unit 114, a rotating mirror 15 for performing fine tracking control by changing the incident position of the laser beam 115 on the imaging lens unit 114 is provided together with the deflection angle detection device 60. Are located. As the configuration of the rotating mirror 15, the configuration shown in FIG. 17 can be adopted. The deflection angle detection device 60 can employ any of the above-described embodiments.
[0098]
In the system configured as described above, first, the recording surface of the recording disk 112 is irradiated with the laser beam 115, the reflected light is received by the imaging lens unit 114, the tracking signal is picked up, the position of the track, Collect information such as the amount of deviation. Based on the information, the rotational position of the arm 113 is coarsely controlled by the drive coil 117 to perform movement between tracks and follow the tracks.
[0099]
Further, in order to perform more precise tracking, the rotating mirror 15 is tilted, the laser beam 115 is deflected, the incident position on the imaging lens unit 114 is shifted, and the radial imaging position on the recording surface is shifted. Move slightly. At this time, the deflection angle of the rotation mirror 15 is detected by the deflection angle detection device 60 and feedback control is performed. For the feedback control, a method similar to the optical signal switching method described with reference to FIG. 18 can be employed.
[0100]
As described above, when the information recording / reproducing system is configured by using the deflection angle detecting device 60 of the present invention, first, the deflection angle detecting device 60 can be made compact, so that the arm 113 can be made small and light. it can. Therefore, there is an advantage that the mechanical response characteristic can be improved. Second, since the detection range of the deflection angle detection device 60 can be widened, a larger deflection angle can be obtained, and even if the distance from the rotating mirror 15 to the imaging lens unit 114 is short, the predetermined incident position can be obtained. Can be obtained, and as a result, the optical path length of the optical system on the arm 113 can be shortened. This has the advantage that the size of the arm 113 can be reduced, and a more compact information recording / reproducing system having excellent mechanical response characteristics can be obtained.
[0101]
As described above, the deflection angle detecting device of the present invention has the following features in addition to the invention described in the claims.
[0102]
(1) The deflection angle detection according to claim 1, wherein a prism filled with a medium having a refractive index of 1 or more is disposed in an optical path between the light source and the reflection surface for detection. apparatus.
[0103]
(2) A part of the prism arranged in the optical path between the light source and the reflective surface for detection is made to pass through a part of the optical path from the reflective surface for detection to the photodetector. The deflection angle detecting device according to the above (1), characterized in that:
[0104]
(3) The deflection angle detection device according to (2), wherein a second prism including a transmission surface having the positive power is disposed between the prism and the photodetector. .
[0105]
(4) The deflection angle detecting device according to (3), wherein the prism and the second prism are joined.
[0106]
(5) The deflection according to any one of (1) to (4), wherein the optical path conversion surface is configured as a beam splitter surface that reflects or transmits a part of light. Angle detector.
[0107]
(6) The optical path conversion surface is configured as a polarizing beam splitter surface that reflects or transmits the light according to the polarization state of the light, and the above (1) to (4). The deflection angle detection device according to any one of the above.
[0108]
(7) The optical path conversion surface is configured as a holographic surface that reflects or transmits the light according to the incident angle or wavelength of the light. The deflection angle detection device according to any one of the above.
[0109]
(8) The optical path conversion surface is configured as a surface that transmits or totally reflects the light according to the incident angle of the light, and any one of the above (1) to (4). The deflection angle detecting device according to any one of the above.
[0110]
(9) The deflection angle detection device according to any one of (1) to (8), wherein the optical path conversion surface has a positive power.
[0111]
(10) The deflection angle detection device according to (9), wherein the optical path conversion surface is formed of a curved surface.
[0112]
(11) The deflection angle detection device according to (9), wherein the optical path conversion surface is configured by a spherical surface.
[0113]
(12) The deflection angle detection device according to (9), wherein the optical path conversion surface is formed of a rotationally symmetric aspherical surface.
[0114]
(13) The deflection angle detecting device according to the above (9), wherein the optical path conversion surface is constituted by a non-rotationally symmetric surface.
[0115]
(14) The deflection angle detecting device according to any one of (1) to (8), wherein the optical path conversion surface is configured as a plane.
[0116]
(15) The device according to any one of (1) to (4) above, further including a surface disposed to face the detection reflection surface, and the surface disposed opposite to the detection reflection surface also serves as an incident surface and a reflection surface. The deflection angle detection device according to any one of the above.
[0117]
(16) The device according to (1) to (1), further including a surface disposed opposite to the reflection surface for detection, wherein the surface disposed opposite has an internal reflection function and a transmission function. The deflection angle detection device according to any one of 4).
[0118]
(17) The device according to (1) to (4), further including a surface disposed opposite to the detection reflection surface, wherein the surface disposed opposite has an internal reflection action by total reflection. The deflection angle detecting device according to any one of the above.
[0119]
(18) The method according to any one of (1) to (4), further comprising: a surface arranged to face the reflection surface for detection, wherein the surface arranged to face is a plane. A deflection angle detection device according to any one of the above.
[0120]
(19) The method according to any one of (1) to (4), further including a surface disposed opposite to the detection reflection surface, wherein the surface disposed opposite to the reflection surface is a curved surface. A deflection angle detection device according to any one of the above.
[0121]
(20) The method according to any one of (1) to (4), further including: a surface disposed to face the detection reflection surface, wherein the surface disposed to face is configured by a spherical surface. A deflection angle detection device according to any one of the above.
[0122]
(21) The method according to any one of (1) to (1), further including a surface arranged to face the reflection surface for detection, wherein the surface arranged to face is constituted by a rotationally symmetric aspherical surface. The deflection angle detection device according to any one of 4).
[0123]
(22) The method according to (1) to (1), further including a surface arranged opposite to the reflection surface for detection, and the surface arranged opposite to the reflection surface being a non-rotationally symmetric surface. The deflection angle detection device according to any one of 4).
[0124]
(23) The deflection angle detection device according to claim 1, wherein an optical member having a positive power is disposed between the light source and the optical path conversion surface.
[0125]
(24) The deflection angle detecting device according to any one of (1) to (4), wherein an incident surface of the prism facing the light source has a positive power.
[0126]
(25) The deflection angle detection device according to any one of (1) to (24), wherein the transmission surface having the positive power is a surface having a spherical surface.
[0127]
(26) The deflection angle according to any one of (1) to (24), wherein the transmission surface having the positive power is a surface having a rotationally symmetric aspherical surface. Detection device.
[0128]
(27) The deflection angle according to any one of (1) to (24), wherein the transmission surface having the positive power is a surface having a non-rotationally symmetric surface. Detection device.
[0129]
(28) The deflection angle detection device according to any one of (1) to (24), wherein the transmission surface having the positive power is a surface having a Fresnel surface. .
[0130]
(29) The deflection angle detection device according to any one of (1) to (28), wherein the photodetector is configured by a one-dimensional PSD (position detection device). .
[0131]
(30) The deflection angle detection device according to any one of (1) to (28), wherein the photodetector is configured by a two-dimensional PSD (position detection device). .
[0132]
(31) The deflection angle detecting device according to any one of (1) to (28), wherein the photodetector includes a four-divided light receiving surface.
[0133]
(32) The deflection angle detecting device according to claim 2, wherein the reflection on the second surface is a total reflection.
[0134]
(33) The deflection angle detection device according to claim 2, wherein the third surface is configured as a half mirror surface.
[0135]
(34) The deflection angle detection device according to claim 2, wherein the third surface is configured as a polarization beam splitter surface.
[0136]
(35) The deflection angle detection device according to claim 2, wherein the third surface is configured as a diffractive optical surface.
[0137]
(36) The deflection angle detection device according to claim 2, wherein the third surface is configured as a holographic optical surface.
[0138]
(37) The deflection angle detecting device according to claim 2, wherein the third surface and the fourth surface are joined.
[0139]
(38) The deflection angle detection device according to claim 2, wherein the first surface is configured as a surface having a positive power.
[0140]
(39) The deflection angle detecting device according to claim 2, wherein the first to fifth surfaces are constituted by Fresnel surfaces.
[0141]
(40) The deflection angle detecting device according to claim 3, wherein the reflection on the second surface is a total reflection.
[0142]
(41) The second surface is configured as a surface having a positive power in both a portion having a reflection function and a portion having a function of emitting light from the prism toward the photodetector. The deflection angle detecting device according to claim 3, wherein:
[0143]
(42) The deflection angle detection device according to claim 3, wherein the first surface is configured as a surface having a positive power.
[0144]
(43) The deflection angle detecting device according to claim 3, wherein the first to fourth surfaces are constituted by Fresnel surfaces.
[0145]
(44) An optical signal switch system using the deflection angle detection device according to any one of (1) to (43).
[0146]
(45) The deflection angle detection device according to any one of (1) to (43), and a deflection angle for controlling a deflection angle of the optical deflection element based on an output from the deflection angle detection device. An optical signal switch system, comprising: a control unit.
[0147]
(46) An information recording / reproducing system using the deflection angle detecting device according to any one of (1) to (43).
[0148]
(47) A deflection angle detection device according to any one of (1) to (43), and a recording surface capable of recording and / or reproducing an information signal by irradiating light. A recording medium having a light source for irradiating a light beam for recording and / or reproducing the information signal on the recording medium, an optical system for imaging the light beam on a recording surface of the recording medium, and Information recording / reproducing comprising: a light deflecting element which is disposed, deflects the light beam in a plane parallel to the recording surface, and has the reflection surface for detection, the inclination angle of which changes in conjunction with the deflection angle. system.
[0149]
(48) A system for deflecting light using the deflection angle detection device according to any one of (1) to (43).
[0150]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the deflection angle detection apparatus of this invention, the angle detection of the reflection surface for detection can be performed in a wide range, and the deflection angle detection apparatus which realized the compact mechanical layout can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a deflection angle detection device according to a first embodiment of the present invention, showing a state where a mirror rotation angle is 0 degrees.
FIG. 2 is a schematic configuration diagram of the deflection angle detection device according to the first embodiment of the present invention, showing a state where the mirror rotation angle is rotated by −10 degrees around the x axis in the yz plane.
FIG. 3 is a schematic configuration diagram of a deflection angle detection device according to the first embodiment of the present invention, showing a state where a mirror rotation angle is rotated by 10 degrees around an x axis in a yz plane.
FIG. 4 is a conceptual diagram of a PSD that can be employed for a photodetector in the deflection angle detection device of the present invention.
FIG. 5 is an explanatory diagram showing a state in which a spot 7a is formed on the sensor light receiving surface 6 of the photodetector 5 when the detecting reflection surface 3 is inclined in a one-dimensional direction (X direction or Y direction). is there.
FIG. 6 is a graph showing the relationship between the amount of tilt of the reflection surface for detection and the output of the photodetector 5;
FIG. 7 is an explanatory diagram showing a state in which a spot 7b is imaged on the sensor light receiving surface 6 of the photodetector 5 when the detection reflecting surface 3 is inclined in a two-dimensional direction.
FIG. 8 is an explanatory diagram showing a state where a spot 7 is imaged on a sensor light receiving surface 6 of a photodetector 5 employing a split photodetector (4-split PD).
FIG. 9 is a schematic configuration diagram of a deflection angle detection device according to a second embodiment of the present invention.
FIG. 10 is a schematic configuration diagram of a deflection angle detection device according to a third embodiment of the present invention.
FIG. 11 is a schematic configuration diagram of a deflection angle detection device according to a fourth embodiment of the present invention.
FIG. 12 is a schematic configuration diagram of a deflection angle detection device according to a fifth embodiment of the present invention.
FIG. 13 is a lateral aberration diagram when the mirror rotation angle is 0 degree, which is the optical path diagram shown in FIG.
14 is a lateral aberration diagram in the state of the optical path diagram shown in FIG. 2 (mirror rotation angle around the X axis −10 degrees).
15 is a lateral aberration diagram in the state of the optical path diagram shown in FIG. 3 (mirror rotation angle around the X axis is 10 degrees).
FIG. 16 is an explanatory diagram showing a schematic configuration of an example of an optical signal switch system using the deflection angle detection device of the present invention.
FIG. 17 is an explanatory diagram showing a cross section perpendicular to the reflection surface of the rotating mirror 15 and a configuration around the cross section.
FIG. 18 is a control block diagram of a deflection angle control means 61 'for performing optical signal switching control by tilting a rotating mirror 15 as another example of the device using the deflection angle detection device according to the present invention.
FIG. 19 is a plan view showing a schematic configuration of an information recording / reproducing system 110 using a deflection angle detecting device according to the present invention.
[Explanation of symbols]
1 Semiconductor laser
1b laser driving means
2,2 'prism
2a, 2'a << first surface
2b, 2'b @ second surface
2c, 2'c {3rd surface
2d, 2'd 4th surface
3 Reflection surface for detection
4 ° eccentric lens
4a 1st surface
4b 2nd surface
5 Photodetector
6 Light detection surface (sensor light receiving surface)
7,7a, 7b spot
8, 8a, 8b, 8c, 8d Light receiving surface
15, 15A, 15B rotating mirror
15a Deflection mirror surface
15b support member
15c reflective surface for detection
15d actuator
60 ° deflection angle detector
61 'deflection angle control means
61'a @ decoding means
61'b @ control unit
101, 101A Input side cable
102 ° collimator unit
103, 103A laser beam (optical signal)
105 output side cable unit
106 optical signal switch system
107 ° imaging unit
108 optical switching device
109, 109B Output side cable
109a entrance
110 Recorded information reproduction system
111 housing
112 recording disk
112a drive shaft
113a rotation axis
114 ° imaging lens unit
115 ° laser
116 ° imaging lens
117 ° drive coil

Claims (3)

A deflection angle detection device for detecting the deflection angle of the light deflection element,
A light source that emits light,
An optical path conversion surface for switching at least a part of the optical path of light emitted from the light source,
A reflection surface for detection provided in the light deflection element, which is arranged on the light path switched by the light path conversion surface,
A light detector that receives light reflected by the reflection surface for detection and detects a deflection angle of the light deflecting element by the light receiving position,
A deflection angle detection device comprising at least a transmission surface having a positive power between the reflection surface for detection and the photodetector. A deflection angle detection device for detecting the deflection angle of the light deflection element,
A light source that emits light,
A prism composed of at least three surfaces,
An eccentric lens composed of two surfaces,
Located on the optical path of light from the light source switched through the prism, a detection reflection surface provided in the light deflection element,
A light detector that receives light reflected by the reflection surface for detection and detects a deflection angle of the light deflecting element by the light receiving position,
A first surface having a function of transmitting incident light from a light source into the prism, a function of reflecting light transmitted through the first surface, and a function of transmitting light reflected by another optically active surface of the prism; A second surface having a function of emitting light from the prism to the detection reflection surface side and a function of transmitting incident light from the detection reflection surface into the prism; and detecting light reflected by the second surface. A third surface having an operation of reflecting toward the light reflection surface and an operation of transmitting light transmitted through the second surface to the photodetector side,
The eccentric lens includes a fourth surface facing the third surface, and a fifth surface which is located between the fourth surface and the photodetector and is a transmission surface having a positive power. A deflection angle detection device, characterized in that: A deflection angle detection device for detecting the deflection angle of the light deflection element,
A light source that emits light,
A prism composed of at least four surfaces;
Located on the optical path of light from the light source switched through the prism, a detection reflection surface provided in the light deflection element,
A light detector that receives light reflected by the reflection surface for detection and detects a deflection angle of the light deflecting element by the light receiving position,
A first surface having a function of transmitting incident light from a light source into the prism; a function of reflecting light transmitted through the first surface toward the detecting reflection surface; and other optics of the prism A second surface having a function of transmitting light transmitted through the working surface and emitting the light from the prism toward the photodetector; and transmitting the light reflected by the second surface and detecting the reflection surface from the prism through the prism. A third surface having an operation of emitting light to the side, and a fourth surface having an operation of transmitting incident light from the reflection surface for detection into the prism,
A deflection angle detecting device, wherein at least one of the first surface and the second surface has a positive power.

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