JP4153234B2

JP4153234B2 - Light receiving / emitting composite unit, manufacturing method thereof, and displacement detection device

Info

Publication number: JP4153234B2
Application number: JP2002127525A
Authority: JP
Inventors: 英明田宮; 佳代子谷口; 明博黒田; 英廣久米
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2002-04-26
Filing date: 2002-04-26
Publication date: 2008-09-24
Anticipated expiration: 2022-04-26
Also published as: JP2003322550A

Description

【０００１】
【発明の属する技術分野】
本発明は、工作機械や半導体製造装置等の可動部分における相対移動位置を検出するための受発光複合ユニット及びその製造方法、変位検出装置に関するものである。
【０００２】
【従来の技術】
従来より、工作機械や半導体製造装置等の可動部分における相対移動位置を検出する装置として、回折格子を用いた光学式の変位検出装置が知られている。
【０００３】
例えば、特開昭６０−９８３０２号公報に提案されている従来の光学式変位測定装置を図８及び図９に示す。図８は、この従来の光学式変位測定装置１００を模式的に示す斜視図であり、図９は、この従来の光学式変位測定装置１００を模式的に示す側面図である。
【０００４】
従来の光学式変位測定装置１００は、工作機械等の可動部分の移動にともない、図中矢印Ｘ１及びＸ２方向に直線移動する回折格子１０１と、光を出射する光源１０２と、光源１０２から出射された光を２本のビームに分割するとともに回折格子１０１からの２つの回折光を重ね合わせ干渉させるハーフミラー１０３と、回折格子１０１で回折された回折光を反射する２つのミラー１０４ａ，１０４ｂと、干渉した２つの回折光を光電変換して干渉信号を生成するフォトディテクタ１０５とを備えている。
【０００５】
光源１０２から出射された光は、ハーフミラー１０３により２本のビームに分割される。この２本のビームはそれぞれ回折格子１０１に照射される。回折格子１０１に照射された２本のビームは、この回折格子１０１で夫々回折され、回折光となる（以下、この回折光を１回回折光と称する）。この１回回折光は夫々ミラー１０４ａ，１０４ｂにより反射される。ミラー１０４ａ，１０４ｂにより反射された１回回折光は、回折格子１０１に再度照射されて再度回折される（以下、この再度回折された回折光を２回回折光と称する）。これら２本の２回回折光は、同一の光路を経てハーフミラー１０３に入射され、夫々重ね合わされて干渉し、フォトディテクタ１０５に照射される。
【０００６】
このような従来の光学式変位測定装置１００では、回折格子１０１における図中矢印Ｘ１、Ｘ２方向の変位を検出することができる。すなわち、光学式変位測定装置１００では、回折格子１０１の移動に応じて、回折格子１０１に基づく２本の２回回折光に位相差が生じる。このため、この光学式変位測定装置１００では、フォトディテクタにより得られる干渉信号から２本の２回回折光の位相差を検出することにより、工作機械等の可動部分の移動位置を測定することができる。
【０００７】
また、特開昭６０−９８３０２号公報に提案されている他の従来の光学式変位測定装置を図１０及び図１１に示す。図１０は、従来の光学式変位測定装置１１０模式的に示す斜視図であり、図１１は、従来の光学式変位測定装置１１０を模式的に示す側面図である。
【０００８】
従来の光学式変位測定装置１１０は、工作機械等の可動部分の移動にともない、図中矢印Ｘ１及びＸ２方向に直線移動する回折格子１１１と、光を出射する光源１１２と、光源１１２から出射された光を２本のビームに分割するとともに回折格子１１１からの２つの回折光を重ね合わせて干渉させるハーフミラー１１３と、ハーフミラー１１３により分割された２本のビームを回折格子上１１１上の同一位置に照射する２つの第１のミラー１１４ａ，１１４ｂと、回折格子１１１で回折された回折光を反射する２つの第２のミラー１１５ａ，１１５ｂと、干渉した２つの回折光を受光して干渉信号を生成するフォトディテクタ１１６とを備えている。
【０００９】
光源１１２から出射された光は、ハーフミラー１１３により２本のビームに分割される。この２本のビームは、それぞれ第１のミラー１１４ａ，１１４ｂに反射されて回折格子１１１上の同一位置に照射される。回折格子１１１に照射された２本のビームは、この回折格子でそれぞれ回折され、１回回折光となる。１回回折光は、それぞれ第２のミラー１１５ａ，１１５ｂにより反射される。またこの１回回折光は、回折格子１１１に再度照射されて回折され、２回回折光となる。これら２本の２回回折光は、同一の光路を経てハーフミラー１１３に入射され重ね合わされて干渉し、フォトディテクタ１１６に照射される。
【００１０】
このような従来の光学式変位測定装置１１０では、回折格子１１１における図中矢印Ｘ１、Ｘ２方向の変位を検出することができる。すなわち、この光学的変位測定装置１１０では、回折格子１１１の移動に応じて、回折格子１１１に基づく２本の２回回折光に位相差が生じる。このため、光学式変位測定装置１１０では、フォトディテクタ１１６により得られる干渉信号から２本の２回回折光の位相差を検出することにより、工作機械等の可動部分の移動位置を測定することができる。
【００１１】
【発明が解決しようとする課題】
しかしながら、上記従来の光学式変位測定装置は、製造工程において、単独に製作された各光学部品を調整しながら組み立てる必要性があるため、各部品の仕上がり精度や特性のばらつきに対して精密な調整を必要とし、工程が複雑化する上に、装置の経時的な安定性に欠き、また装置全体の小型化、軽量化を図る上で大きな障害となっていた。
【００１２】
また、光源から出射する光の偏光軸が、ハーフミラー１０３、１１３で１対１に分配される角度になるように調整しなければならず、さらに複雑な工程を余儀なく導入せざるを得ず、また装置内に余分な面積を要するという問題点があった。
【００１３】
そこで本発明は上述した問題点に鑑みて案出されたものであり、その目的とするところは、経時的安定性に優れ、小型軽量化に適した変位検出装置を提供することにある。
【００１４】
【課題を解決するための手段】
本発明に係る受発光複合ユニットは、上述の課題を解決するために、光を出射する光源と、上記光源から出射された光を、互いに偏光成分が異なる２つの光に分離して外部光学系へ出射し、当該外部光学系から反射される上記２つの光を合成して合成光を生成する偏光ビームスプリッタと、上記偏光ビームスプリッタにより生成された合成光を複数に分割する光分割手段と、上記分割された合成光を夫々所定の偏光成分のみ透過させる偏光手段と、上記光源と上記偏光ビームスプリッタの間に配設され、上記光源から出射される光の偏光状態を変化させて上記偏光ビームスプリッタへ導く第１の部分と、上記光分割手段と上記偏光手段との間に配設され、上記分割された合成光の偏光状態を夫々変化させる第２の部分とを含む位相板と、上記偏光手段を透過した干渉光を夫々光電変換して干渉信号を生成する受光手段とを備え、上記偏光手段と、上記位相板と、上記光分割手段とを順次積層させて構成することを特徴とする。
【００１５】
また本発明に係る受発光複合ユニットの製造方法は、上述の課題を解決するため、発光素子から発光され、また位相板により偏光状態を変化させた光を２つに分離して外部光学系へ出射し、当該外部光学系から反射される上記出射した光を互いに合成させ、当該合成させた光を上記位相板により偏光状態を変化させて受光素子を介して検出する受発光複合ユニットの製造方法において、合成させた光を複数に分割する光分岐層と、上記位相板と、所定の偏光成分のみ透過させる偏光板を順次積層して積層板を形成する工程と、上記形成した積層板を上記受発光ユニット単位で切り出す切出工程と、上記偏光板を透過した光を夫々上記受光素子へ導く複合レンズ部を上記切り出した積層板に夫々接合し、接合した上記複合レンズ部に上記受光素子及び上記発光素子からなる受発光部を接合する接合工程とを有することを特徴とする。
【００１６】
更に、本発明に係る変位検出装置は、上述の課題を解決するため、反射型の回折格子が配された被検査物について格子ベクトル方向の変位を干渉信号に基づいて検出する変位検出装置において、光を出射する光源と、上記光源から出射された光を互いに偏光成分が異なる２つの光に分離して出射する偏光ビームスプリッタと、上記偏光ビームスプリッタから出射された２つの光を上記回折格子の格子面に結像させる結像手段と、上記ビームスプリッタから出射された２つの光が上記回折格子により回折されて得られる２つの第１の回折光を夫々反射する反射手段と、上記反射手段により反射された上記第１の回折光が上記回折格子により回折されて得られる２つの第２の回折光を合成させて合成光を生成し、当該合成光を複数に分割する光分割手段と、上記分割された合成光を夫々所定の偏光成分のみ透過させる偏光手段と、上記光源と上記偏光ビームスプリッタの間に配設され、上記光源から出射される光の偏光状態を変化させて上記偏光ビームスプリッタへ導く第１の部分と、上記光分割手段と上記偏光手段との間に配設され、上記分割された合成光の偏光状態を夫々変化させる第２の部分とを含む位相板と、上記偏光手段を透過した干渉光を夫々光電変換して上記干渉信号を生成する受光手段とを備え、上記偏光手段と、上記位相板と、上記光分割手段とを順次積層させて構成することを特徴とする。
また、本発明に係る変位検出装置は、上述の課題を解決するため、透過型の回折格子が配された被検査物について格子ベクトル方向の変位を干渉信号に基づいて検出する変位検出装置において、光を出射する光源と、上記光源から出射された光を互いに偏光成分が異なる２つの光に分離して出射する偏光ビームスプリッタと、上記ビームスプリッタから出射された２つの光が上記回折格子により回折されて得られる２つの第１の回折光を夫々反射する反射手段と、上記反射手段により反射された上記第１の回折光が上記回折格子により回折されて得られる２つの第２の回折光を合成させて合成光を生成し、当該合成光を複数に分割する光分割手段と、上記分割された合成光を夫々所定の偏光成分のみ透過させる偏光手段と、上記光源と上記偏光ビームスプリッタの間に配設され、上記光源から出射される光の偏光状態を変化させて上記偏光ビームスプリッタへ導く第１の部分と、上記光分割手段と上記偏光手段との間に配設され、上記分割された合成光の偏光状態を夫々変化させる第２の部分とを含む位相板と、上記偏光手段を透過した干渉光を夫々光電変換して上記干渉信号を生成する受光手段とを備え、上記偏光手段と、上記位相板と、上記光分割手段とを順次積層させて構成することを特徴とする。
【００１７】
【発明の実施の形態】
先ず、本発明を適用した第１の実施の形態の変位検出装置について説明する。
【００１８】
本発明の第１の実施の形態における変位検出装置１０は、図１に示すように、工作機械等の可動部分に取り付けられ直線移動する透過型の回折格子１１と、
発光素子により発光された光を２つの光Ｌａ１，Ｌａ２に分離して出射し、回折格子１１により回折された２つの２回回折光Ｌｃ１，Ｌｃ２を互いに干渉させて干渉信号を検出する受発光複合ユニット１２と、受発光複合ユニット１２から出射された２つの光Ｌａ１,Ｌａ２を回折格子１１に照射するとともに、回折格子１１からの２つの２回回折光Ｌｃ１、Ｌｃ２を受発光複合ユニット１２へ導く反射部材１３ａ、１３ｂと、回折格子１１からの２つの１回回折光Ｌｂ１、Ｌｂ２を反射して再度回折格子１１に照射する反射光学系１４とを備えている。
【００１９】
回折格子１１は、図２に示すように、例えば薄板状の形状を有しており、その表面に狭いスリットや溝等、または屈折率が分布した格子が所定間隔毎に刻まれている。このような回折格子１１に入射された光は、表面に刻まれたスリット等により回折し、該回折格子１１を透過する。回折により生じる回折光は、格子の間隔と光の波長で定まる方向に発生する。
【００２０】
ここで発明の実施の形態を説明するにあたり、格子が形成されている回折格子１１の面を、格子面１１ａと称する。なお、回折格子１１が透過型の場合には、光が入射される面と回折光が発生する面とをともに格子面１１ａと呼ぶ。また、回折格子１１の格子が形成された方向（図２中矢印Ｃ１、Ｃ２方向）、すなわち、格子の透過率や反射率、溝の深さ等の変化の方向を表す格子ベクトルに対して垂直な方向であって且つ格子面１１ａに平行な方向を格子方向と称する。格子が形成された方向に垂直な方向であり、且つ格子面１１ａに平行な方向（図３中矢印Ｄ１、Ｄ２方向）、すなわち、回折格子１１の格子ベクトルに対して平行な方向を格子ベクトル方向と称する。なお、これら回折格子１１の各方向については、本発明の第１の実施の形態のみならず、他の実施の形態においても同様に称するものとする。
【００２１】
この回折格子１１は、工作機械等の可動部分に取り付けられ、該可動部分の移動にともなって、図２中矢印Ｄ１、Ｄ２方向、すなわち格子ベクトル方向に移動する。
【００２２】
なお、本発明では回折格子の種類は限定されず、上述したように機械的に溝等が形成されたもののみならず、例えば、感光性樹脂に干渉縞を焼き付けて作成したものであっても良い。
【００２３】
反射部材１３ａは、光Ｌａ１を反射して回折格子１１の格子面１１ａの所定の位置に照射する。この光Ｌａ１が回折格子１１により回折されることにより１回回折光Ｌｂ１が得られる。反射部材１３ｂは、光Ｌａ２を反射して、回折格子１１の格子面１１ａの所定の位置に照射する。この光Ｌａ２が回折格子１１により回折されることにより１回回折光Ｌｂ２が得られる。
【００２４】
また反射部材１３ａには、１回回折光Ｌｂ１が回折格子１１により回折されることにより生じる２回回折光Ｌｃ１が照射される。反射部材１３ａは、この２回回折光Ｌｃ１を反射して受発光複合ユニット１２に照射する。また反射部材１３ｂには、１回回折光Ｌｂ２が回折格子１１により回折されることにより生じる２回回折光Ｌｃ２が照射される。反射部材１３ｂは、この２回回折光Ｌｃ２を反射して受発光複合ユニット１２に照射する。
【００２５】
ちなみに、この反射部材１３ａにより回折格子１１の格子面１１ａに照射する所定の位置と、反射部材１３ｂにより回折格子１１の格子面１１ａに照射する所定の位置とを近づけても良い。これにより、回折格子１１内の厚みムラ等によって生じる光路長の差を小さくすることができ、スケールの厚みムラ等による誤差を軽減させることができる。
【００２６】
反射光学系１４は、１回回折光Ｌｂ１を反射して再度回折格子１１に照射する反射器２６と、１回回折光Ｌｂ２を反射して再度回折格子１１に照射する反射器２７と、１回回折光Ｌｂ１の偏光状態を変える１／４波長板ＷＰ１と、１回回折光Ｌｂ２の偏光状態を変える１／４波長板ＷＰ２とを有する。
【００２７】
反射器２６には、１／４波長板ＷＰ１を通過した１回回折光Ｌｂ１が照射される。反射器２６は、この１回回折光Ｌｂ１が入射経路と同じ経路を逆行するように、該１回回折光Ｌｂ１を垂直に反射する。ちなみに、この反射器２６に照射される１回回折光Ｌｂ１は、１／４波長板ＷＰ１を既に通過しており、またこの反射器２６を反射する１回回折光Ｌｂ１は１／４波長板ＷＰ１を再度通過するため、偏光方向が９０°回転された状態で、再度回折格子１１へ照射されることになる。
【００２８】
反射器２７には、１／４波長板ＷＰ２を通過した１回回折光Ｌｂ２が照射される。反射器２７は、この１回回折光Ｌｂ２が入射経路と同じ経路を逆行するように、該１回回折光Ｌｂ２を垂直に反射する。ちなみに、この反射器２７に照射される１回回折光Ｌｂ２は、１／４波長板ＷＰ２を既に通過しており、またこの反射器２７を反射する１回回折光Ｌｂ２は１／４波長板ＷＰ２を再度通過するため、偏光方向が９０°回転された状態で、再度回折格子１１へ照射されることになる。
【００２９】
なおこの反射光学系１４は、上述した構成に限定されるものではなく、例えば、反射プリズムを用いて構成しても良い。図３は、反射光学系１４に反射プリズムを用いた変位検出装置１０の構成を示している。この図３において、図１と同一の構成要素、部材については説明を省略する。
【００３０】
反射プリズム３０には、１／４波長板ＷＰ３１が順次積層されている。この反射プリズム３０の反射面３０ａには、１／４波長板ＷＰ３１を通過した１回回折光Ｌｂ１、Ｌｂ２が照射される。反射面３０ａは、この１回回折光Ｌｂ１、Ｌｂ２が入射経路と同じ経路を逆行するように、当該１回回折光Ｌｂ１、Ｌｂ２を垂直に反射する。ちなみに、の反射面３０ａに照射される１回回折光Ｌｂ１,Ｌｂ２は、１／４波長板ＷＰ３１を既に通過しており、またこの反射面３０ａを反射する１回回折光Ｌｂ１,Ｌｂ２は、１／４波長板ＷＰ３１を再度通過するため、偏光方向が９０°回転された状態で、再度回折格子１１へ照射されることになる。
【００３１】
次に、受発光複合ユニット１２の詳細について説明をする。受発光複合ユニット１２は、図４に示すように発光素子や受光素子を収容する収容部材４０と、複数のレンズ（４１ａ，４１＿１，４１＿２，４１＿３，４１＿４）からなる複合レンズ部４１と、所定の偏光成分のみを透過させる偏光部４２（４２＿１、４２＿２、４２＿３、４２＿４）と、光の偏光状態を変化させる位相板４３と、回折格子１１に照射する光を分割し或いは回折格子１１を回折することより得られる２回回折光Ｌｃ１、Ｌｃ２を分離するための光分岐部４４とを備える。
【００３２】
収容部材４０は、光Ｌａを出射する光源５１と、後述する干渉光を光電変換して干渉信号を生成する受光素子５２（５２＿１、５２＿２、５２＿３、５２＿４）と、光源５１を設置して電気信号を印加し或いは反射面５３ａにより光路制御を行うための半導体基板５３と、受光素子を設置して電気信号を取り出すための半導体基板５４とを有する。
【００３３】
光分岐部４４は、光源５１から出射された光Ｌａを２つの光Ｌａ１、Ｌａ２に分割して出射するとともに、反射部材１３ａ，１３ｂからの２回回折光Ｌｃ１、Ｌｃ２を合成させて合成光Ｌｄを生成する偏光分離部５８と、偏光分離部５８から照射される合成光Ｌｄを合成光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４に分割する光分岐膜５９＿１、５９＿２、５９＿３、５９＿４とを有する。
【００３４】
光源５１は、レーザ光等の可干渉光を発光する素子である。なお、この光源５１は、例えば可干渉距離の小さいレーザ光を発光するマルチモードの半導体レーザ等であっても良い。
【００３５】
受光素子５２は、受光面に対して照射された光を、その光量に応じた電気信号に変換する光電変換素子であり、例えば、フォトディテクタ等からなるものである。この受光素子５２は、受光面に対して照射された各干渉光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４を受光して、その光量に応じた干渉信号を生成する。
【００３６】
受光素子５２により光電変換されて得られた干渉信号は、半導体基板５４を介して図示しない位置検出部により検出される。この図示しない位置検出部は、得られた干渉信号に基づいて位相差を求め、回折格子１１の相対移動位置を示す位置信号を出力する。
【００３７】
複合レンズ部４１は、所定の開口数を有するレンズ等の光学素子からなるものである。レンズ４１ａには、光源５１から出射された光Ｌａが入射される。レンズ４１ａは、入射された光Ｌａを所定のビーム径で回折格子１１の格子面１１ａや、反射器２６、２７に結像させることができる。この第１の実施の形態においては、透過型の回折格子１１を採用しているため、出射する光Laは通常反射器２６、２７に結像させる。このため、格子面１１ａ上において照射されるビーム径を大きくすることができ、格子面１１ａ上のゴミや傷の影響を軽減させることが可能となる。またこのような、外部に出射する光、受光する光のビーム径を共に制御する複合レンズ部４１を同一パッケージ内に配置することにより、集積度を高めることができ、また作製工程を簡略化でき、装置全体の信頼性を高めることができる。
【００３８】
またレンズ４１＿１，４１＿２，４１＿３，４１＿４には、偏光部４２から出射された干渉光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４がそれぞれ入射される。レンズ４１＿１，４１＿２，４１＿３，４１＿４は、入射された各干渉光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４を受光素子５２＿１，５２＿２，５２＿３，５２＿４に結像させる。その結像点は、必ずしもビーム径が最小となる点とする必要はない。またこの複合レンズ部４１は、上述のように複数のレンズを連ねた構造に限定されるものではなく、例えば、上述のレンズ４１ａ，４１＿１，４１＿２，４１＿３，４１＿４を一体として１つのレンズで構成しても良い。また、この複合レンズ部４１を構成する各レンズは、ビームを収束させる場合のみならず、例えば平行光を出射させたり、或いは発散光を出射するようにしても良い。
【００３９】
偏光部４２＿１、４２＿２、４２＿３、４２＿４は、位相板４３から入射された各合成光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４について所定の偏光成分のみを透過させ、干渉光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４としてレンズ部４１へ出射する。各偏光部４２は４５°間隔（例えば５°、５０°、９５°、１４０°）に配置されていれば足り、偏光部４２の取り付け時の姿勢について制約を受けずに配置することができる。なお、このような偏光部４２を位相板４３と複合レンズ部４１の間に設けることにより、ユニット全体をコンパクトな構成にすることができる利点もある。
【００４０】
位相板４３は、偏光部４２と、光分岐部４４の間に挟み込まれるように積層される。この位相板４３は、例えば１／４波長板からなり、円偏光と直線偏光間の変換を行う。ちなみにこの位相板４３は、光源５１からレンズ４１ａを介して光Ｌａが入射される。位相板４３は、例えば直線偏光である光Ｌａを円偏光に変換して偏光分離部５８へ照射する。また、この位相板４３は、光分岐膜５９＿１、５９＿２、５９＿３、５９＿４から出射された合成光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４を受けて円偏光に変換し、上述した偏光部４２へ出射する。すなわち、光源５１からの光Ｌａの変換と光分岐膜５９からの光Ｌｄの変換とを１つの位相板４３により共用する構成を採用する。
【００４１】
偏光分離部５８は、例えば偏光ビームスプリッタ等からなり、光源５１から出射された光Ｌａが位相板４３を介して入射される。この偏光分離部５８は、入射された光Ｌａの一部を反射して光Ｌａ１を生成し、入射された光Ｌａの一部を透過して光Ｌａ２を生成する。なおこの偏光分離部５８は、光Ｌａ１,Ｌａ２を、偏光成分が直交するＳ偏光とＰ偏光に分割しても良い。この場合光Ｌａ１はＳ偏光と光となり、また光Ｌａ２は、Ｐ偏光の光となる。またこの偏光分離部５８には、回折格子１１からの２回回折光Ｌｃ１及び２回回折光Ｌｃ２が入射される。偏光分離部５８は、２つの２回回折光Ｌｃ１、Ｌｃ２を重ね合わせて合成させ、該合成光Ｌｄを光分岐膜５９へ出射する。
【００４２】
光分岐膜５９＿１、５９＿２、５９＿３、５９＿４の各反射率は、夫々１／４，１／３，１／２，１に設定されている（すなわち、光分岐膜５９＿４は全反射面となっている）。このため、入射された合成光Ｌｄをほぼ同一の光量で、合成光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４に分割することが可能となる。
【００４３】
なお受発光複合ユニット１２には、上述した収容部材４０と、複合レンズ部４１と、偏光部４２と、位相板４３と、光分岐部４４が、同一パッケージ内に配設され独立ユニットとして構成される。またこれらの各部材は、夫々積層されて一体となるように構成されている。
【００４４】
すなわち受発光複合ユニット１２は、各部材をパッケージ化して一体構造とすることにより、精密な位置調整が容易になり、また部品の配置スペースを大きくとる必要がなくなり、変位検出装置全体の小型化、軽量化を図ることができる。また、各部材を同一の収容部材内に収納することにより、環境変化や経時変化の影響を軽減させることができ、調整時のずれ等を最小限に抑えることができ、ひいては受発光複合ユニット１２全体の信頼性を高めることができる。
【００４５】
次に本発明を適用した第１の実施の形態の変位検出装置１０の動作例について説明をする。
【００４６】
先ず光源５１から出射された光Ｌａは、例えば図４に示すように半導体基板５３の反射面５３ａにより反射されてレンズ４１ａへ照射される。光Ｌａは、このレンズ４１ａにより像変換され、例えば１／４波長板からなる位相板４３へ照射される。
【００４７】
位相板４３へ照射された光Ｌａは、該位相板４３により円偏光に変化させられる。すなわち、位相板４３を介して出射される直線偏光の光Ｌａは、光源５１から出射される光の偏光方向の如何によらず、円偏光に変化させることができる。これにより、光源５１から出射される光の偏光成分を従来技術の如く、光源５１から出射する光の偏光成分を偏光分離部５８に対してほぼ４５°にすることなく、自由に選択することも可能となる。
【００４８】
位相板４３を出射された光Ｌａは、偏光分離部５８により例えばＳ偏光とＰ偏光の光Ｌａ１、Ｌａ２に分離され、反射部材１３ａ，１３ｂを介して、回折格子１１へ入射させる。ちなみにこの回折格子１１における光Ｌａ１の入射角をθa、光Ｌａ２の入射角をθb、また１回回折光Ｌｂ１の回折角をθa´、１回回折光Ｌｂ２の回折角をθb´としたとき、以下の式（１１）、（１２）が成立する。
ｓｉｎθa＋ｓｉｎθa´＝ｍλ／ｄ（１１）
ｓｉｎθb＋ｓｉｎθb´＝ｍλ／ｄ（１２）
ｄ：回折格子のピッチ
λ：光の波長
ｍ：回折次数
１回回折光Ｌｂ１、Ｌｂ２はそれぞれ反射器２６、２７を垂直に反射する。このとき、１回回折光Ｌｂ１、Ｌｂ２は、１／４波長板ＷＰ１、ＷＰ２を２回通過するため、偏光方向は夫々９０°回転させられる。このため、元々Ｓ偏光であった１回回折光Ｌｂ１はＰ偏光に変換され、また元々Ｐ偏光であった１回回折光Ｌｂ２は、Ｓ偏光に変換される。
【００４９】
次に、反射器２６、２７を夫々反射した１回回折光Ｌｂ１、Ｌｂ２は、再度回折格子１１により回折されて２回回折光Ｌｃ１、Ｌｃ２となり、同一の光路を経て再度偏光分離部５８へ到達する。偏光分離部５８では、このＰ偏光である２回回折光Ｌｃ１と、Ｓ偏光である２回回折光Ｌｃ２とを重ね合わせて合成させ、合成光Ｌｄを生成する。
【００５０】
合成光Ｌｄは光分岐膜５９＿１、５９＿２、５９＿３、５９＿４を介してＬｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４に分割される。この分割された合成光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４は、夫々位相板４３に照射される。このとき２回回折光Ｌｃ１、Ｌｃ２は、互いに逆周りの円偏光になる。この合成光Ｌｄを特定の偏光成分のみ透過する偏光板を通じて受光すると、この合成光Ｌｄについて、重ね合わせた２つの２回回折光Ｌｃ１、Ｌｃ２の振幅をＡ１、Ａ２とし、回折格子１１の格子ベクトル方向への移動量をｘ、初期位相をδとし、またＫ＝２π／ｄ（ｄは格子ピッチ）として、１回目、２回目の回折で夫々１次の回折光を利用した場合は、特定の偏光成分を取り出すと以下の（１３）式のような干渉信号Ｉが得られる。
Ｉ＝Ａ１^２＋Ａ２^２＋２・Ａ１・Ａ２ｃｏｓ（４・Ｋ・ｘ＋δ）（１３）
この干渉信号Ｉは、回折格子１１が格子ベクトル方向へｄ／４移動することにより１周期分変化する。δは、重ね合わせた２つの２回回折光Ｌｃ１、Ｌｃ２の光路長の差に依存する量である。
【００５１】
この位相板４３を出射した各合成光Ｌｄ１、Ｌｄ２、Ｌｄ３、Ｌｄ４は、夫々偏光部４２により、所定の偏光成分のみ透過させられる。各偏光部４２は、夫々４５°間隔になるように設定されているが、本例では偏光部４２＿１は０°の偏光方向のみ透過させるようにし、また偏光部４２＿２は４５°の偏光方向のみ透過させるようにし、また偏光部４２＿３は、９０°の偏光方向のみ透過させるようにし、さらに偏光部４２＿４は、１３５°の偏光方向のみ透過させるようにする。このとき各偏光部４２を透過した干渉光Ｌｄ１、Ｌｄ２、Ｌｄ３、Ｌｄ４の強度は、夫々以下の式（２１）〜（２４）で表される。
Ｂ＋Ａｃｏｓ（４・Ｋ・ｘ＋δ）（２１）
Ｂ＋Ａｃｏｓ（４・Ｋ・ｘ＋９０°＋δ）（２２）
Ｂ＋Ａｃｏｓ（４・Ｋ・ｘ＋１８０°＋δ）（２３）
Ｂ＋Ａｃｏｓ（４・Ｋ・ｘ＋２７０°＋δ）（２４）
Ｂ＝１／４（Ａ１^２＋Ａ２^２）
Ａ＝１／２・Ａ１・Ａ２
式（２１）は、偏光部４２＿１を透過した干渉光Ｌｄ１の強度を表した式であり、式（２２）は、偏光部４２＿２を透過した干渉光Ｌｄ２の強度を表した式であり、式（２３）は、偏光部４２＿３を透過した干渉光Ｌｄ３の強度を表した式であり、式（２４）は、偏光部４２＿４を透過した干渉光Ｌｄ４の強度を表した式である。これらの式で表される干渉光Ｌｄ１は、レンズ４１＿１，４１＿２，４１＿３，４１＿４を介して、受光素子５２＿１，５２＿２，５２＿３，５２＿４に結像される。すなわち各受光素子５２は、上述の式で表される干渉光Ｌｄを光電変換して干渉信号を生成することとなる。
【００５２】
式（２１）と式（２３）とを減算すると、干渉信号の直流成分を除去することができる。また式（２２）と式（２４）とを減算すると、干渉信号の直流成分を除去することができる。また減算された信号は、互いに位相が９０°異なるため、回折格子に移動方向を検知するための信号を得ることができる。
【００５３】
このように、本発明を適用した変位検出装置１０では、位相板４３が偏光部４２と、光分岐部４４の間に挟み込まれるように積層される。この位相板４３は、直線偏光である光Ｌａを円偏光に変換して偏光分離部５８へ照射することができる。これにより、従来の如く光源５１から出射する光Ｌａの偏光成分を偏光分離部５８に対してほぼ４５°になるように光源５１を配置することなく、自由に選択することも可能となる。これに伴い、受発光ユニット１２において部品配置に余分な面積を要するという問題点を解消し、よりコンパクトな構成にすることができる。またこの位相板４３は、光分岐膜５９＿１、５９＿２、５９＿３、５９＿４から出射された合成光Ｌｄ１,Ｌｄ２,Ｌｄ３,Ｌｄ４を受けて偏光方向が回転する直線偏光に変換し、上述した偏光部４２へ出射することができる。これにより各偏光部４２の偏光方向を図５に示す上から見た図のように４５°間隔（例えば５０°、５°、１４０°、９５°）にすれば足り、偏光部４２の取り付け時における制約を緩和させることができ、ひいては製造工程を簡略化や製造コストの削減を図ることも可能となる。またこの位相板４３は、光源５１からの光Ｌａの変換と光分岐膜５９からの光Ｌｄの変換とを１つの位相板４３により共用する構成を採用するため、寸法管理や容易となり更なる製造コストの削減を図ることも可能となる。
【００５４】
次に本発明を適用した第２の実施の形態の変位検出装置について説明する。第１の実施の形態における変位検出装置１０と同一の構成要素、部材については同一の番号を付して説明を引用し、本実施の形態における説明を省略する。
【００５５】
本発明の第２の実施の形態における変位検出装置７０は、図６に示すように、工作機械等の可動部分に取り付けられ直線移動する反射型の回折格子７１と、発光素子により発光された光を２つの光Ｌａ１，Ｌａ２に分離して出射し、回折格子７１により回折された２つの２回回折光Ｌｃ１，Ｌｃ２を互いに干渉させて干渉信号を検出する受発光複合ユニット１２と、受発光複合ユニット１２から出射された２つの光Ｌａ１,Ｌａ２を回折格子７１に照射するとともに、回折格子７１からの２つの２回回折光Ｌｃ１、Ｌｃ２を受発光複合ユニット１２へ導く反射部材７３ａ、７３ｂと、回折格子７１からの２つの１回回折光Ｌｂ１、Ｌｂ２を反射して再度回折格子７１に照射する反射光学系７４とを備えている。
【００５６】
回折格子７１は、例えば薄板状の形状を有しており、その表面に狭いスリットや溝等、または屈折率が分布した格子が所定間隔毎に刻まれている。このような回折格子７１に入射された光は、表面に刻まれたスリット等により回折し、該回折格子７１を反射する。回折により生じる回折光は、格子の間隔と光の波長で定まる方向に発生する。
【００５７】
なお、本発明では回折格子の種類は限定されず、上述したように機械的に溝等が形成されたもののみならず、例えば、感光性樹脂に干渉縞を焼き付けて作成したものであっても良い。
【００５８】
反射部材７３ａは、光Ｌａ１を反射して回折格子７１の格子面７１ａの所定の位置に照射する。この光Ｌａ１が回折格子７１により回折されることにより１回回折光Ｌｂ１が得られる。反射部材７３ｂは、光Ｌａ２を反射して、回折格子７１の格子面７１ａの所定の位置に照射する。この光Ｌａ２が回折格子７１により回折されることにより１回回折光Ｌｂ２が得られる。
【００５９】
また反射部材７３ａには、１回回折光Ｌｂ１が回折格子７１により回折されることにより生じる２回回折光Ｌｃ１が照射される。反射部材７３ａは、この２回回折光Ｌｃ１を反射して受発光複合ユニット１２に照射する。また反射部材７３ｂには、１回回折光Ｌｂ２が回折格子７１により回折されることにより生じる２回回折光Ｌｃ２が照射される。反射部材７３ｂは、この２回回折光Ｌｃ２を反射して受発光複合ユニット１２に照射する。
【００６０】
ちなみに、この反射部材７３ａにより回折格子７１の格子面７１ａに照射する所定の位置と、反射部材７３ｂにより回折格子７１の格子面７１ａに照射する所定の位置とが、同一位置になるように結像させる。このときビーム径は、格子面７１ａ上のゴミや傷の影響を受けないような大きさが望ましい。またこの結像点は、必ずしもビーム径が最小となる点とする必要はなく、ビームの像内での光路長の差が最小となる点が格子面７１ａ上に位置するようにしても良い。
【００６１】
反射光学系７４は、１回回折光Ｌｂ１を反射して再度回折格子７１に照射する反射器７６と、１回回折光Ｌｂ２を反射して再度回折格子７１に照射する反射器７７と、１回回折光Ｌｂ１の偏光状態を変える１／４波長板ＷＰ７１と、１回回折光Ｌｂ２の偏光状態を変える１／４波長板ＷＰ７２とを有する。
【００６２】
反射器７６には、１／４波長板ＷＰ７１を通過した１回回折光Ｌｂ１が照射される。反射器７６は、この１回回折光Ｌｂ１が入射経路と同じ経路を逆行するように、該１回回折光Ｌｂ１を垂直に反射する。ちなみに、この反射器７６に照射される１回回折光Ｌｂ１は、１／４波長板ＷＰ７１を既に通過しており、またこの反射器７６を反射する１回回折光Ｌｂ１は１／４波長板ＷＰ７１を再度通過するため、偏光方向が９０°回転された状態で、再度回折格子７１へ照射されることになる。
【００６３】
反射器７７には、１／４波長板ＷＰ７２を通過した１回回折光Ｌｂ２が照射される。反射器７７は、この１回回折光Ｌｂ２が入射経路と同じ経路を逆行するように、該１回回折光Ｌｂ２を垂直に反射する。
【００６４】
反射器７７には、１／４波長板ＷＰ７２を通過した１回回折光Ｌｂ２が照射される。反射器７７は、この１回回折光Ｌｂ２が入射経路と同じ経路を逆行するように、該１回回折光Ｌｂ２を垂直に反射する。ちなみに、この反射器７７に照射される１回回折光Ｌｂ２は、１／４波長板ＷＰ７２を既に通過しており、またこの反射器７７を反射する１回回折光Ｌｂ２は１／４波長板ＷＰ７２を再度通過するため、偏光方向が９０°回転された状態で、再度回折格子７１へ照射されることになる。
【００６５】
この第２の実施の形態における受発光複合ユニット１２の詳細と、第２の実施の形態における動作例は、第１の実施の形態の説明を引用する。
【００６６】
すなわち、反射型の回折格子７１を用いる第２の実施の形態に係る変位検出装置７０は、受発光複合ユニット１２における各部材をパッケージ化して一体構造とすることにより、精密な位置調整が容易になり、また部品の配置スペースを大きくとる必要がなくなり、変位検出装置全体の小型化、軽量化を図ることができる。また各部材を同一の収容部材内に収納することにより、環境変化や経時変化の影響を軽減させることができ、調整時のずれ等を最小限に抑えることができ、ひいては受発光複合ユニット１２全体の信頼性を高めることができる。
【００６７】
また、第２の実施の形態においても、光源５１からの光Ｌａの変換と光分岐膜５９からの光Ｌｄの変換とを１つの位相板４３により共用する構成を採用するため、寸法管理や容易となり更なる製造コストの削減を図ることが可能となる。
【００６８】
次に、本発明を適用した受発光複合ユニット１２の作製方法について図７を用いて説明をする。
【００６９】
先ず、ステップＳ１１において、複数の光分岐部４４を連ねた光分岐部４４層と、複数の受発光複合ユニット１２の面積分の位相板４３と、複数の偏光部４２を連ねた偏光部４２層を作製する。そして光分岐部４４層と、上記位相板４３と、偏光部４２層を順次積層して積層板８１を作製する。この積層板８１を作製する際には、偏光部４２層の上に位相板４３を積層し、さらにその上に光分岐部４４層を積層しても良いし、また光分岐部４４層の上に位相板４３を積層し、さらにその上に偏光部４２層を設けても良い。
【００７０】
次にステップＳ１２へ移行し、作製した積層板８１をスライスして複数に分割する。このステップＳ１２において分割した個々の積層板はそれぞれ１個分の受発光複合ユニット１２に相当する。
【００７１】
次にステップＳ１３へ移行し、分割した個々の積層板８１毎に、複合レンズ部４１を接合し、さらにその接合した複合レンズ部４１に収容部材４０を接合する。
【００７２】
すなわち、本発明を適用した受発光複合ユニット１２の作製工程では、最初に加工しやすい大きさの光学部品を張り合わせ、後からスライスして個々の受発光複合ユニット１２を構成する大きさまで分割し、最後に複合レンズ部４１と、収容部材４０を張り合わせて完成させるため、生産工程をより簡単にすることができ、製造コストを削減させることができる。
【００７３】
特に本発明に係る受発光複合ユニット１２は、各部材をパッケージ化して一体構造とすることにより、精密な位置調整が容易になり、また部品の配置スペースを大きくとる必要がなくなり、小型化、軽量化を図れる点に利点がある。このため、上述の製造工程を採用することができ、さらなる小型、低価格化等を実現することができる。
【００７４】
以上、本発明を適用した第１〜第２の実施の形態の変位検出装置を説明した。各実施の形態の変位検出装置では、格子が所定の間隔で平行に設けられた回折格子１１、７１を用いているが、本発明では、このような格子が平行に設けられた回折格子を用いなくても良い。例えばロータリエンコーダ等放射状の格子が設けられた回折格子を用いて角度検出をするようにしても良い。
【００７５】
また、本発明では、明暗を記録した振幅型の回折格子、屈折率変化や形状変化を記録した位相型の回折格子を用いても良く、その回折格子のタイプは限定されるものではない。
【００７６】
また、各実施の形態の変位検出装置では、回折格子１１,７１を工作機械等の可動部分に取り付けて、この回折格子１１が可動部分の移動に応じて移動する場合について説明したが、本発明では、回折格子１１,７１と、変位検出装置とが相対的に移動すれば良いことは勿論である。
【００７７】
【発明の効果】
以上詳細に説明したように、本発明に係る変位検出装置及び受発光複合ユニットは、位相板が偏光部と光分岐部の間に挟み込まれるように積層される。この位相板は、直線偏光である光を円偏光に変換して偏光分離部へ照射することができる。これにより、従来の如く光源から出射する光の偏光成分を偏光分離部に対してほぼ４５°になるように光源を配置することなく、自由に選択することも可能となる。これに伴い、受発光ユニット１２において部品配置に余分な面積を要するという問題点を解消し、よりコンパクトな構成にすることができる。またこの位相板は、光分岐膜から出射された合成光を受けて、上述した偏光部へ出射することができる。これにより各偏光部の偏光方向を４５°間隔にすれば足り、偏光部の取り付け時における制約を緩和させることができ、ひいては製造工程を簡略化や製造コストの削減を図ることも可能となる。またこの位相板は、光源からの光の変換と光分岐膜からの光の変換とを１つの位相板により共用する構成を採用するため、寸法管理や容易となり更なる製造コストの削減を図ることも可能となる。
【００７８】
また、本発明に係る変位検出装置は、各部材をパッケージ化して一体構造とすることにより、精密な位置調整が容易になり、また部品の配置スペースを大きくとる必要がなくなり、変位検出装置全体の小型化、軽量化を図ることができる。また、各部材を同一の収容部材内に収納することにより、環境変化や経時変化の影響を軽減させることができ、調整時のずれ等を最小限に抑えることができ、ひいては装置全体の信頼性を高めることができる。
【図面の簡単な説明】
【図１】本発明に係る変位検出装置の構成を説明するための図である。
【図２】変位検出に用いる回折格子の斜視図である。
【図３】反射光学系に反射プリズムを用いる場合について説明するための図である。
【図４】受発光複合ユニットの構成図である。
【図５】受発光複合ユニットを上下面から描いた図である。
【図６】反射型の回折格子を用いる変位検出装置について説明するための図である。
【図７】受発光複合ユニットの作製方法について説明するための図である。
【図８】従来の光学式変位測定装置の斜視図である。
【図９】従来の光学式変位測定装置の側面図である。
【図１０】従来の他の光学式変位測定装置の斜視図である。
【図１１】従来の他の光学式変位測定装置の側面図である。
【符号の説明】
１０変位検出装置、１１回折格子、１２受発光複合ユニット、１３反射部材、１４反射光学系、２６,２７反射器、ＷＰ１,ＷＰ２１／４波長板、４０収容部材、４１複合レンズ部、４２偏光部、４３位相板、４４光分岐部、５１光源、５２受光素子、５３,５４半導体基板、５８偏光分離部、５９光分岐膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light receiving / emitting composite unit for detecting a relative movement position in a movable part such as a machine tool or a semiconductor manufacturing apparatus, a manufacturing method thereof, and a displacement detection apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an optical displacement detection device using a diffraction grating is known as a device for detecting a relative movement position in a movable part such as a machine tool or a semiconductor manufacturing apparatus.
[0003]
For example, a conventional optical displacement measuring device proposed in Japanese Patent Laid-Open No. 60-98302 is shown in FIGS. FIG. 8 is a perspective view schematically showing this conventional optical displacement measuring device 100, and FIG. 9 is a side view schematically showing this conventional optical displacement measuring device 100. As shown in FIG.
[0004]
The conventional optical displacement measuring device 100 is a diffraction grating 101 that linearly moves in the directions of arrows X1 and X2 in the drawing, a light source 102 that emits light, and a light source 102 that is emitted from the light source 102 as a movable part such as a machine tool moves. A half mirror 103 that splits the divided light into two beams and overlaps and interferes with the two diffracted lights from the diffraction grating 101, and two mirrors 104a and 104b that reflect the diffracted light diffracted by the diffraction grating 101, And a photodetector 105 that photoelectrically converts the two diffracted light beams that interfere with each other to generate an interference signal.
[0005]
The light emitted from the light source 102 is split into two beams by the half mirror 103. These two beams are applied to the diffraction grating 101, respectively. The two beams irradiated on the diffraction grating 101 are each diffracted by the diffraction grating 101 to become diffracted light (hereinafter, this diffracted light is referred to as one-time diffracted light). This one-time diffracted light is reflected by mirrors 104a and 104b, respectively. The once-diffracted light reflected by the mirrors 104a and 104b is irradiated again on the diffraction grating 101 and diffracted again (hereinafter, this diffracted diffracted light is referred to as twice-diffracted light). These two two-time diffracted lights are incident on the half mirror 103 through the same optical path, are superimposed and interfere with each other, and are irradiated to the photodetector 105.
[0006]
Such a conventional optical displacement measuring apparatus 100 can detect the displacement of the diffraction grating 101 in the directions of arrows X1 and X2 in the drawing. That is, in the optical displacement measuring apparatus 100, a phase difference is generated between the two twice-diffracted lights based on the diffraction grating 101 in accordance with the movement of the diffraction grating 101. For this reason, in this optical displacement measuring apparatus 100, the moving position of a movable part such as a machine tool can be measured by detecting the phase difference between the two twice-diffracted lights from the interference signal obtained by the photodetector. .
[0007]
FIG. 10 and FIG. 11 show another conventional optical displacement measuring device proposed in Japanese Patent Laid-Open No. 60-98302. 10 is a perspective view schematically showing a conventional optical displacement measuring device 110, and FIG. 11 is a side view schematically showing the conventional optical displacement measuring device 110. As shown in FIG.
[0008]
The conventional optical displacement measuring device 110 is emitted from the diffraction grating 111 that linearly moves in the directions of the arrows X1 and X2 in the drawing, the light source 112 that emits light, and the light source 112 as the movable part such as a machine tool moves. The half mirror 113 that splits the divided light into two beams and superimposes the two diffracted lights from the diffraction grating 111 to interfere with each other, and the two beams divided by the half mirror 113 on the diffraction grating 111 are the same The two first mirrors 114a and 114b that irradiate the position, the two second mirrors 115a and 115b that reflect the diffracted light diffracted by the diffraction grating 111, and the interference signal that receives the two interfered diffracted lights And a photo detector 116 for generating.
[0009]
The light emitted from the light source 112 is divided into two beams by the half mirror 113. These two beams are reflected by the first mirrors 114 a and 114 b and irradiated to the same position on the diffraction grating 111. The two beams irradiated on the diffraction grating 111 are each diffracted by the diffraction grating and become one-time diffracted light. The one-time diffracted light is reflected by the second mirrors 115a and 115b, respectively. Further, the one-time diffracted light is irradiated again on the diffraction grating 111 and diffracted to become twice-diffracted light. These two two-time diffracted beams are incident on the half mirror 113 through the same optical path, are superimposed on each other, interfere with each other, and are irradiated on the photodetector 116.
[0010]
Such a conventional optical displacement measuring device 110 can detect the displacement of the diffraction grating 111 in the directions of the arrows X1 and X2 in the figure. That is, in this optical displacement measuring device 110, a phase difference is generated between the two twice-diffracted lights based on the diffraction grating 111 in accordance with the movement of the diffraction grating 111. Therefore, the optical displacement measuring device 110 can measure the moving position of a movable part such as a machine tool by detecting the phase difference between the two twice-diffracted lights from the interference signal obtained by the photodetector 116. .
[0011]
[Problems to be solved by the invention]
However, the above-mentioned conventional optical displacement measuring device needs to be assembled while adjusting each optical component manufactured independently in the manufacturing process, so that precise adjustment is made for variations in finish accuracy and characteristics of each component. In addition, the process is complicated, the stability of the apparatus over time is lacking, and it has become a major obstacle to reducing the overall size and weight of the apparatus.
[0012]
In addition, the polarization axis of the light emitted from the light source must be adjusted so that the half mirrors 103 and 113 are distributed in a one-to-one angle, and more complicated processes must be introduced. There is also a problem that an extra area is required in the apparatus.
[0013]
Accordingly, the present invention has been devised in view of the above-described problems, and an object of the present invention is to provide a displacement detection device that has excellent temporal stability and is suitable for reduction in size and weight.
[0014]
[Means for Solving the Problems]
  In order to solve the above-described problems, the light receiving / emitting composite unit according to the present invention separates the light source that emits light and the light emitted from the light source into two light components having different polarization components from each other. Polarizing beam splitter that generates combined light by combining the two light beams emitted from the external optical system and reflected from the external optical systemAnd aboveA light splitting means for splitting the combined light generated by the polarizing beam splitter into a plurality of parts, and a polarizing means for transmitting the split combined light only with predetermined polarization components,A first portion disposed between the light source and the polarization beam splitter, and changing the polarization state of the light emitted from the light source to guide the light to the polarization beam splitter; and the light splitting means and the polarization means A phase plate that is disposed between and includes a second portion that changes the polarization state of the divided combined light, respectively.A light receiving means for photoelectrically converting the interference light transmitted through the polarizing means to generate an interference signal.The polarizing means, the phase plate, and the light splitting means are sequentially laminated.It is characterized by.
[0015]
In addition, in order to solve the above-described problem, the method for manufacturing a light emitting / receiving composite unit according to the present invention separates light emitted from the light emitting element and whose polarization state has been changed by the phase plate into two to an external optical system. A method of manufacturing a light receiving and emitting composite unit that emits and combines the emitted light reflected from the external optical system and detects the synthesized light through a light receiving element while changing a polarization state by the phase plate The step of forming a laminated plate by sequentially laminating the light splitting layer that divides the combined light into a plurality of layers, the phase plate, and a polarizing plate that transmits only a predetermined polarization component; A cutting process for cutting out in units of light receiving and emitting units, and a composite lens part for guiding light transmitted through the polarizing plate to the light receiving element, respectively, are joined to the cut laminated plate, and the light receiving element is joined to the joined composite lens part. And characterized by having a bonding step of bonding the light receiving and emitting unit comprised of the light emitting element.
[0016]
  Furthermore,In order to solve the above-described problem, a displacement detection device according to the present invention is a displacement detection device that detects a displacement in the grating vector direction of an inspection object provided with a reflective diffraction grating based on an interference signal. A light source that emits light and a polarization beam splitter that separates and emits light emitted from the light source into two lights having different polarization componentsAnd aboveAn imaging means for forming an image of two lights emitted from the polarizing beam splitter on the grating surface of the diffraction grating, and two second lights obtained by diffracting the two lights emitted from the beam splitter by the diffraction grating. Reflective means for reflecting each diffracted light of 1 and two second diffracted lights obtained by diffracting the first diffracted light reflected by the reflecting means by the diffraction grating to generate combined light And a light splitting means for splitting the combined light into a plurality of parts, and a polarizing means for transmitting only the predetermined polarization components of the split combined light,A first portion disposed between the light source and the polarization beam splitter, and changing the polarization state of the light emitted from the light source to guide the light to the polarization beam splitter; and the light splitting means and the polarization means A phase plate that is disposed between and includes a second portion that changes the polarization state of the divided combined light, respectively.A light receiving means for photoelectrically converting the interference light transmitted through the polarization means to generate the interference signal.The polarizing means, the phase plate, and the light splitting means are sequentially laminated.It is characterized by.
  Moreover, the displacement detection apparatus according to the present invention solves the above-described problems,In a displacement detection apparatus for detecting a displacement in a grating vector direction based on an interference signal with respect to an inspection object having a transmission type diffraction grating, polarization components of the light source that emits light and the light emitted from the light source are mutually different. A polarizing beam splitter that divides and emits two different lights, and a reflecting means that reflects the two first diffracted lights obtained by diffracting the two lights emitted from the beam splitter by the diffraction grating, respectively; Light splitting that synthesizes two second diffracted lights obtained by diffracting the first diffracted light reflected by the reflecting means by the diffraction grating to generate composite light, and divides the composite light into a plurality of parts Means, a polarizing means for transmitting the divided combined light only with a predetermined polarization component, and a light source disposed between the light source and the polarizing beam splitter, and for the light emitted from the light source. A first portion that changes the light state and guides it to the polarization beam splitter, and a second portion that is disposed between the light splitting means and the polarization means and changes the polarization state of the split combined light, respectively. And a light receiving means for photoelectrically converting the interference light transmitted through the polarization means to generate the interference signal, and the polarization means, the phase plate, and the light splitting means. It is characterized by being sequentially laminated.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
First, a displacement detection apparatus according to a first embodiment to which the present invention is applied will be described.
[0018]
As shown in FIG. 1, a displacement detection device 10 according to the first embodiment of the present invention is attached to a movable part such as a machine tool and linearly moves a transmissive diffraction grating 11.
The light emitting / receiving composite that detects the interference signal by separating the light emitted by the light emitting element into two light La1 and La2 and emitting the light, and causing the two two-time diffracted lights Lc1 and Lc2 diffracted by the diffraction grating 11 to interfere with each other. The unit 12 and the two lights La1 and La2 emitted from the light receiving / emitting composite unit 12 are irradiated to the diffraction grating 11, and the two two-time diffracted lights Lc1 and Lc2 from the diffraction grating 11 are guided to the light receiving / emitting composite unit 12. Reflecting members 13a and 13b and a reflecting optical system 14 that reflects the two one-time diffracted beams Lb1 and Lb2 from the diffraction grating 11 and irradiates the diffraction grating 11 again.
[0019]
As shown in FIG. 2, the diffraction grating 11 has, for example, a thin plate shape, and narrow slits, grooves, or the like having a refractive index distributed on its surface are inscribed at predetermined intervals. The light incident on the diffraction grating 11 is diffracted by a slit or the like carved on the surface and passes through the diffraction grating 11. Diffracted light generated by diffraction is generated in a direction determined by the interval between the gratings and the wavelength of the light.
[0020]
Here, in describing the embodiment of the invention, the surface of the diffraction grating 11 on which the grating is formed is referred to as a grating surface 11a. When the diffraction grating 11 is a transmissive type, the surface on which light is incident and the surface on which diffracted light is generated are both referred to as a grating surface 11a. Also, the direction in which the grating of the diffraction grating 11 is formed (the directions of arrows C1 and C2 in FIG. 2), that is, perpendicular to the grating vector representing the direction of change in the transmittance and reflectance of the grating, the depth of the groove, and the like. A direction that is parallel to the lattice plane 11a is called a lattice direction. The direction perpendicular to the direction in which the grating is formed and parallel to the grating surface 11a (the directions of arrows D1 and D2 in FIG. 3), that is, the direction parallel to the grating vector of the diffraction grating 11 is the grating vector direction. Called. In addition, about each direction of these diffraction gratings 11, it shall refer similarly not only in the 1st Embodiment of this invention but in other embodiment.
[0021]
The diffraction grating 11 is attached to a movable part such as a machine tool, and moves in the directions of arrows D1 and D2 in FIG. 2, that is, the grating vector direction as the movable part moves.
[0022]
In the present invention, the type of the diffraction grating is not limited, and it is not limited to those in which grooves or the like are mechanically formed as described above. For example, the diffraction grating may be formed by baking interference fringes on a photosensitive resin. good.
[0023]
The reflecting member 13a reflects the light La1 and irradiates a predetermined position on the grating surface 11a of the diffraction grating 11. The light La1 is diffracted by the diffraction grating 11, whereby the one-time diffracted light Lb1 is obtained. The reflecting member 13b reflects the light La2 and irradiates a predetermined position on the grating surface 11a of the diffraction grating 11. The light La2 is diffracted by the diffraction grating 11, whereby the one-time diffracted light Lb2 is obtained.
[0024]
The reflecting member 13a is irradiated with the twice-diffracted light Lc1 generated when the once-diffracted light Lb1 is diffracted by the diffraction grating 11. The reflecting member 13a reflects the two-time diffracted light Lc1 and irradiates the light receiving / emitting composite unit 12. The reflecting member 13b is irradiated with the twice-diffracted light Lc2 that is generated when the once-diffracted light Lb2 is diffracted by the diffraction grating 11. The reflection member 13b reflects the twice-diffracted light Lc2 and irradiates the light receiving / emitting composite unit 12.
[0025]
Incidentally, the predetermined position where the reflecting member 13a irradiates the grating surface 11a of the diffraction grating 11 and the predetermined position where the reflecting member 13b irradiates the grating surface 11a of the diffraction grating 11 may be brought closer to each other. Thereby, a difference in optical path length caused by thickness unevenness in the diffraction grating 11 can be reduced, and an error due to scale thickness unevenness can be reduced.
[0026]
The reflection optical system 14 includes a reflector 26 that reflects the diffracted light Lb1 once and irradiates the diffraction grating 11 again, a reflector 27 that reflects the diffracted light Lb2 once and irradiates the diffraction grating 11 again, and once. It has a quarter-wave plate WP1 that changes the polarization state of the diffracted light Lb1, and a quarter-wave plate WP2 that changes the polarization state of the one-time diffracted light Lb2.
[0027]
The reflector 26 is irradiated with the one-time diffracted light Lb1 that has passed through the quarter-wave plate WP1. The reflector 26 reflects the one-time diffracted light Lb1 vertically so that the one-time diffracted light Lb1 travels the same path as the incident path. Incidentally, the one-time diffracted light Lb1 irradiated to the reflector 26 has already passed through the quarter-wave plate WP1, and the one-time diffracted light Lb1 reflected from the reflector 26 is the quarter-wave plate WP1. , The diffraction grating 11 is again irradiated with the polarization direction rotated by 90 °.
[0028]
The reflector 27 is irradiated with the one-time diffracted light Lb2 that has passed through the quarter-wave plate WP2. The reflector 27 reflects the one-time diffracted light Lb2 vertically so that the one-time diffracted light Lb2 travels the same path as the incident path. Incidentally, the one-time diffracted light Lb2 applied to the reflector 27 has already passed through the quarter-wave plate WP2, and the one-time diffracted light Lb2 reflected by the reflector 27 is the quarter-wave plate WP2. , The diffraction grating 11 is again irradiated with the polarization direction rotated by 90 °.
[0029]
The reflective optical system 14 is not limited to the above-described configuration, and may be configured using, for example, a reflective prism. FIG. 3 shows a configuration of the displacement detection apparatus 10 using a reflecting prism in the reflecting optical system 14. In FIG. 3, the description of the same components and members as those in FIG. 1 is omitted.
[0030]
A quarter wavelength plate WP31 is sequentially stacked on the reflecting prism 30. The reflecting surface 30a of the reflecting prism 30 is irradiated with the one-time diffracted lights Lb1 and Lb2 that have passed through the quarter-wave plate WP31. The reflecting surface 30a reflects the one-time diffracted beams Lb1 and Lb2 vertically so that the one-time diffracted beams Lb1 and Lb2 travel in the same path as the incident path. Incidentally, the one-time diffracted beams Lb1 and Lb2 applied to the reflecting surface 30a have already passed through the quarter-wave plate WP31, and the one-time diffracted beams Lb1 and Lb2 reflected by the reflecting surface 30a are 1 In order to pass through the / 4 wavelength plate WP31 again, the diffraction grating 11 is irradiated again with the polarization direction rotated by 90 °.
[0031]
Next, details of the light emitting / receiving composite unit 12 will be described. As shown in FIG. 4, the light receiving / emitting composite unit 12 includes a housing member 40 that houses a light emitting element and a light receiving element, a composite lens unit 41 including a plurality of lenses (41a, 41_1, 41_2, 41_3, 41_4), Polarizing unit 42 (42_1, 42_2, 42_3, 42_4) that transmits only the polarization component, phase plate 43 that changes the polarization state of the light, and splitting the light applied to diffraction grating 11 or diffracting diffraction grating 11 And an optical branching unit 44 for separating the two-time diffracted beams Lc1 and Lc2 obtained.
[0032]
The housing member 40 is provided with a light source 51 that emits light La, a light receiving element 52 (52_1, 52_2, 52_3, 52_4) that photoelectrically converts interference light, which will be described later, and an optical signal. Or a semiconductor substrate 53 for controlling the optical path by the reflecting surface 53a, and a semiconductor substrate 54 for taking out an electric signal by installing a light receiving element.
[0033]
The light branching unit 44 divides and emits the light La emitted from the light source 51 into two lights La1 and La2, and combines the two-time diffracted lights Lc1 and Lc2 from the reflecting members 13a and 13b to produce a combined light Ld. And a light splitting film 59_1, 59_2, 59_3, 59_4 for splitting the combined light Ld emitted from the polarization splitting unit 58 into the combined light Ld1, Ld2, Ld3, Ld4.
[0034]
The light source 51 is an element that emits coherent light such as laser light. The light source 51 may be, for example, a multimode semiconductor laser that emits laser light having a small coherence distance.
[0035]
The light receiving element 52 is a photoelectric conversion element that converts the light irradiated to the light receiving surface into an electric signal corresponding to the light amount, and includes, for example, a photodetector. The light receiving element 52 receives the interference lights Ld1, Ld2, Ld3, and Ld4 irradiated to the light receiving surface, and generates an interference signal corresponding to the light quantity.
[0036]
An interference signal obtained by photoelectric conversion by the light receiving element 52 is detected by a position detection unit (not shown) via the semiconductor substrate 54. The position detection unit (not shown) obtains a phase difference based on the obtained interference signal and outputs a position signal indicating the relative movement position of the diffraction grating 11.
[0037]
The compound lens unit 41 is composed of an optical element such as a lens having a predetermined numerical aperture. The light La emitted from the light source 51 is incident on the lens 41a. The lens 41a can image the incident light La on the grating surface 11a of the diffraction grating 11 and the reflectors 26 and 27 with a predetermined beam diameter. In the first embodiment, since the transmissive diffraction grating 11 is employed, the emitted light La is normally imaged on the reflectors 26 and 27. For this reason, the beam diameter irradiated on the grating surface 11a can be increased, and the influence of dust and scratches on the grating surface 11a can be reduced. Further, by arranging the compound lens portion 41 for controlling both the beam diameter of the light emitted to the outside and the light received in the same package, the degree of integration can be increased and the manufacturing process can be simplified. Therefore, the reliability of the entire apparatus can be improved.
[0038]
Further, the interference lights Ld1, Ld2, Ld3, and Ld4 emitted from the polarization unit 42 are respectively incident on the lenses 41_1, 41_2, 41_3, and 41_4. The lenses 41_1, 41_2, 41_3, and 41_4 cause the incident interference lights Ld1, Ld2, Ld3, and Ld4 to form an image on the light receiving elements 52_1, 52_2, 52_3, and 52_4. The image forming point does not necessarily need to be a point where the beam diameter is minimized. Further, the compound lens unit 41 is not limited to a structure in which a plurality of lenses are connected as described above. For example, the above-described lenses 41a, 41_1, 41_2, 41_3, and 41_4 are integrated into a single lens. May be. Further, each lens constituting the compound lens unit 41 may not only converge the beam but also emit, for example, parallel light or emit divergent light.
[0039]
The polarization units 42_1, 42_2, 42_3, and 42_4 transmit only a predetermined polarization component of each of the combined lights Ld1, Ld2, Ld3, and Ld4 incident from the phase plate 43, and are lens units as interference lights Ld1, Ld2, Ld3, and Ld4. 41. It is sufficient that the polarizing portions 42 are arranged at intervals of 45 ° (for example, 5 °, 50 °, 95 °, 140 °), and the polarizing portions 42 can be arranged without being restricted in posture. In addition, by providing such a polarization unit 42 between the phase plate 43 and the compound lens unit 41, there is an advantage that the entire unit can be made compact.
[0040]
The phase plate 43 is stacked so as to be sandwiched between the polarization unit 42 and the light branching unit 44. The phase plate 43 is made of, for example, a quarter wavelength plate and converts between circularly polarized light and linearly polarized light. Incidentally, the light La is incident on the phase plate 43 from the light source 51 through the lens 41a. The phase plate 43 converts, for example, linearly polarized light La into circularly polarized light and irradiates the polarized light separating unit 58. The phase plate 43 receives the combined lights Ld1, Ld2, Ld3, and Ld4 emitted from the light branch films 59_1, 59_2, 59_3, and 59_4, converts them into circularly polarized light, and emits the light to the polarizing unit 42 described above. That is, a configuration is adopted in which the conversion of the light La from the light source 51 and the conversion of the light Ld from the light branching film 59 are shared by one phase plate 43.
[0041]
The polarization separation unit 58 includes, for example, a polarization beam splitter and the like, and light La emitted from the light source 51 enters through the phase plate 43. The polarization separation unit 58 reflects the part of the incident light La to generate the light La1, and transmits the part of the incident light La to generate the light La2. The polarization separation unit 58 may divide the light La1 and La2 into S-polarized light and P-polarized light whose polarization components are orthogonal to each other. In this case, the light La1 becomes S-polarized light and the light La2 becomes P-polarized light. In addition, the twice-diffracted light Lc1 and the twice-diffracted light Lc2 from the diffraction grating 11 are incident on the polarization separation unit 58. The polarization separation unit 58 superimposes and combines the two two-time diffracted beams Lc1 and Lc2, and emits the combined beam Ld to the light branching film 59.
[0042]
The reflectivities of the light branch films 59_1, 59_2, 59_3, and 59_4 are set to 1/4, 1/3, 1/2, and 1, respectively (that is, the light branch film 59_4 is a total reflection surface). ). For this reason, it is possible to divide the incident combined light Ld into combined light Ld1, Ld2, Ld3, and Ld4 with substantially the same amount of light.
[0043]
In the light emitting / receiving composite unit 12, the housing member 40, the composite lens unit 41, the polarizing unit 42, the phase plate 43, and the light branching unit 44 described above are arranged in the same package and configured as an independent unit. The Each of these members is configured to be laminated and integrated.
[0044]
That is, the light emitting / receiving composite unit 12 is formed by integrating each member into an integrated structure, thereby facilitating precise position adjustment and eliminating the need for a large arrangement space for the components. Weight reduction can be achieved. In addition, by housing each member in the same housing member, it is possible to reduce the influence of environmental changes and changes over time, and to minimize deviations during adjustment. Overall reliability can be increased.
[0045]
Next, an operation example of the displacement detection apparatus 10 according to the first embodiment to which the present invention is applied will be described.
[0046]
First, the light La emitted from the light source 51 is reflected by the reflecting surface 53a of the semiconductor substrate 53 and irradiated onto the lens 41a, for example, as shown in FIG. The light La is image-converted by the lens 41a and is irradiated onto a phase plate 43 made of, for example, a quarter wavelength plate.
[0047]
The light La irradiated to the phase plate 43 is changed into circularly polarized light by the phase plate 43. That is, the linearly polarized light La emitted through the phase plate 43 can be changed to circularly polarized light regardless of the polarization direction of the light emitted from the light source 51. As a result, the polarization component of the light emitted from the light source 51 can be freely selected without making the polarization component of the light emitted from the light source 51 approximately 45 ° with respect to the polarization separation unit 58 as in the prior art. It becomes possible.
[0048]
The light La emitted from the phase plate 43 is separated into, for example, S-polarized light and P-polarized light La1 and La2 by the polarization separation unit 58, and is incident on the diffraction grating 11 via the reflecting members 13a and 13b. Incidentally, when the incident angle of the light La1 in the diffraction grating 11 is θa, the incident angle of the light La2 is θb, the diffraction angle of the one-time diffracted light Lb1 is θa ′, and the diffraction angle of the one-time diffracted light Lb2 is θb ′. The following expressions (11) and (12) are established.
sin θa + sin θa ′ = mλ / d (11)
sin θb + sin θb ′ = mλ / d (12)
d: Pitch of the diffraction grating
λ: Wavelength of light
m: diffraction order
The one-time diffracted beams Lb1 and Lb2 vertically reflect the reflectors 26 and 27, respectively. At this time, since the one-time diffracted lights Lb1 and Lb2 pass through the quarter-wave plates WP1 and WP2 twice, the polarization directions are rotated by 90 °, respectively. Therefore, the one-time diffracted light Lb1 that was originally S-polarized light is converted to P-polarized light, and the one-time diffracted light Lb2 that was originally P-polarized light is converted to S-polarized light.
[0049]
Next, the one-time diffracted lights Lb1 and Lb2 reflected by the reflectors 26 and 27 are diffracted by the diffraction grating 11 again to become two-time diffracted lights Lc1 and Lc2, and reach the polarization separation unit 58 again through the same optical path. To do. In the polarization separation unit 58, the two-time diffracted light Lc1 that is P-polarized light and the two-time diffracted light Lc2 that is S-polarized light are superimposed and combined to generate a combined light Ld.
[0050]
The combined light Ld is divided into Ld1, Ld2, Ld3, and Ld4 through the light branch films 59_1, 59_2, 59_3, and 59_4. The divided combined lights Ld1, Ld2, Ld3, and Ld4 are irradiated to the phase plate 43, respectively. At this time, the twice-diffracted beams Lc1 and Lc2 are circularly polarized light opposite to each other. When this synthesized light Ld is received through a polarizing plate that transmits only a specific polarization component, the amplitude of the two two-time diffracted lights Lc1 and Lc2 superimposed on this synthesized light Ld is A1 and A2, and the grating vector of the diffraction grating 11 The amount of movement in the direction is x, the initial phase is δ, and K = 2π / d (d is the grating pitch). When the polarization component is extracted, an interference signal I such as the following equation (13) is obtained.
I = A1²+ A2²+2 · A1 · A2 cos (4 · K · x + δ) (13)
The interference signal I changes by one period when the diffraction grating 11 moves d / 4 in the grating vector direction. δ is an amount depending on the difference in optical path length between the two overlapped two-time diffracted beams Lc1 and Lc2.
[0051]
Each of the combined lights Ld1, Ld2, Ld3, and Ld4 emitted from the phase plate 43 is allowed to pass through only a predetermined polarization component by the polarization unit. Each polarization unit 42 is set to have an interval of 45 °, but in this example, the polarization unit 42_1 transmits only the polarization direction of 0 °, and the polarization unit 42_2 transmits only the polarization direction of 45 °. The polarizing unit 42_3 transmits only the 90 ° polarization direction, and the polarizing unit 42_4 transmits only the 135 ° polarization direction. At this time, the intensities of the interference lights Ld1, Ld2, Ld3, and Ld4 transmitted through the polarization units 42 are expressed by the following equations (21) to (24), respectively.
B + Acos (4 ・ K ・ x + δ) (21)
B + Acos (4 · K · x + 90 ° + δ) (22)
B + Acos (4 · K · x + 180 ° + δ) (23)
B + Acos (4 · K · x + 270 ° + δ) (24)
B = 1/4 (A1²+ A2²)
A = 1/2 ・ A1 ・ A2
Expression (21) is an expression representing the intensity of the interference light Ld1 transmitted through the polarizing section 42_1, and Expression (22) is an expression representing the intensity of the interference light Ld2 transmitted through the polarizing section 42_2. 23) is an expression representing the intensity of the interference light Ld3 transmitted through the polarizing section 42_3, and Expression (24) is an expression representing the intensity of the interference light Ld4 transmitted through the polarizing section 42_4. The interference light Ld1 represented by these equations is focused on the light receiving elements 52_1, 52_2, 52_3, and 52_4 via the lenses 41_1, 41_2, 41_3, and 41_4. That is, each light receiving element 52 generates an interference signal by photoelectrically converting the interference light Ld represented by the above formula.
[0052]
By subtracting Equation (21) and Equation (23), the DC component of the interference signal can be removed. Further, by subtracting Equation (22) and Equation (24), the DC component of the interference signal can be removed. Further, since the subtracted signals are 90 ° out of phase with each other, a signal for detecting the moving direction can be obtained by the diffraction grating.
[0053]
As described above, in the displacement detection device 10 to which the present invention is applied, the phase plate 43 is stacked so as to be sandwiched between the polarization unit 42 and the light branching unit 44. The phase plate 43 can convert the light La, which is linearly polarized light, into circularly polarized light and irradiate the polarized light separating unit 58. Thus, it is possible to freely select the polarization component of the light La emitted from the light source 51 without disposing the light source 51 so that the polarization component of the light La is approximately 45 ° with respect to the polarization separation unit 58 as in the prior art. Along with this, the problem that an extra area is required for component placement in the light emitting / receiving unit 12 can be solved, and a more compact configuration can be achieved. The phase plate 43 receives the combined lights Ld1, Ld2, Ld3, and Ld4 emitted from the light branching films 59_1, 59_2, 59_3, and 59_4, converts them into linearly polarized light whose polarization direction is rotated, and transmits it to the polarizing unit 42 described above. Can be emitted. As a result, it is sufficient that the polarization direction of each polarization section 42 is set at 45 ° intervals (for example, 50 °, 5 °, 140 °, and 95 °) as shown in FIG. It is possible to alleviate the restrictions on the manufacturing process, thereby simplifying the manufacturing process and reducing the manufacturing cost. Further, since the phase plate 43 employs a configuration in which the conversion of the light La from the light source 51 and the conversion of the light Ld from the light branching film 59 are shared by one phase plate 43, dimensional management becomes easy and further manufacture becomes possible. Costs can be reduced.
[0054]
Next, a displacement detection apparatus according to a second embodiment to which the present invention is applied will be described. The same components and members as those of the displacement detection device 10 in the first embodiment are denoted by the same reference numerals, and the description thereof is cited, and the description in the present embodiment is omitted.
[0055]
As shown in FIG. 6, the displacement detection device 70 according to the second embodiment of the present invention includes a reflective diffraction grating 71 that is attached to a movable part such as a machine tool and moves linearly, and light emitted by a light emitting element. Are separated into two lights La1 and La2, and the two light diffracted lights Lc1 and Lc2 diffracted by the diffraction grating 71 are caused to interfere with each other to detect an interference signal, Reflecting members 73a and 73b that irradiate the diffraction grating 71 with the two lights La1 and La2 emitted from the unit 12, and guide the two two-time diffracted lights Lc1 and Lc2 from the diffraction grating 71 to the light emitting / receiving composite unit 12. A reflection optical system 74 that reflects the two one-time diffracted beams Lb1 and Lb2 from the diffraction grating 71 and irradiates the diffraction grating 71 again is provided.
[0056]
The diffraction grating 71 has, for example, a thin plate shape, and narrow slits, grooves, or the like having a refractive index distributed on its surface are inscribed at predetermined intervals. The light incident on the diffraction grating 71 is diffracted by a slit or the like carved on the surface and reflected by the diffraction grating 71. Diffracted light generated by diffraction is generated in a direction determined by the interval between the gratings and the wavelength of the light.
[0057]
In the present invention, the type of the diffraction grating is not limited, and it is not limited to those in which grooves or the like are mechanically formed as described above. For example, the diffraction grating may be formed by baking interference fringes on a photosensitive resin. good.
[0058]
The reflection member 73a reflects the light La1 and irradiates it to a predetermined position on the grating surface 71a of the diffraction grating 71. The light La1 is diffracted by the diffraction grating 71, whereby the one-time diffracted light Lb1 is obtained. The reflecting member 73b reflects the light La2 and irradiates a predetermined position on the grating surface 71a of the diffraction grating 71. The light La2 is diffracted by the diffraction grating 71, whereby a one-time diffracted light Lb2 is obtained.
[0059]
Further, the reflection member 73a is irradiated with the twice-diffracted light Lc1 generated by diffracting the one-time diffracted light Lb1 by the diffraction grating 71. The reflection member 73a reflects the two-time diffracted light Lc1 and irradiates the light receiving / emitting composite unit 12. The reflection member 73b is irradiated with the twice-diffracted light Lc2 that is generated when the once-diffracted light Lb2 is diffracted by the diffraction grating 71. The reflection member 73b reflects the two-time diffracted light Lc2 and irradiates the light receiving / emitting composite unit 12.
[0060]
Incidentally, the image is formed such that the predetermined position irradiated to the grating surface 71a of the diffraction grating 71 by the reflecting member 73a and the predetermined position irradiated to the grating surface 71a of the diffraction grating 71 by the reflecting member 73b are the same position. Let At this time, the beam diameter is desirably large enough not to be affected by dust and scratches on the grating surface 71a. Further, the image forming point does not necessarily need to be a point where the beam diameter is minimum, and the point where the difference in the optical path length in the beam image is minimum may be located on the grating surface 71a.
[0061]
The reflection optical system 74 includes a reflector 76 that reflects the diffracted light Lb1 once and irradiates the diffraction grating 71 again, a reflector 77 that reflects the diffracted light Lb2 once and irradiates the diffraction grating 71 again, and once. A quarter-wave plate WP71 that changes the polarization state of the diffracted light Lb1 and a quarter-wave plate WP72 that changes the polarization state of the one-time diffracted light Lb2 are provided.
[0062]
The reflector 76 is irradiated with the one-time diffracted light Lb1 that has passed through the quarter-wave plate WP71. The reflector 76 reflects the one-time diffracted light Lb1 vertically so that the one-time diffracted light Lb1 travels in the same path as the incident path. Incidentally, the one-time diffracted light Lb1 irradiated to the reflector 76 has already passed through the quarter-wave plate WP71, and the one-time diffracted light Lb1 reflected by the reflector 76 is the quarter-wave plate WP71. , The diffraction grating 71 is irradiated again with the polarization direction rotated by 90 °.
[0063]
The reflector 77 is irradiated with the one-time diffracted light Lb2 that has passed through the quarter-wave plate WP72. The reflector 77 reflects the one-time diffracted light Lb2 vertically so that the one-time diffracted light Lb2 travels the same path as the incident path.
[0064]
The reflector 77 is irradiated with the one-time diffracted light Lb2 that has passed through the quarter-wave plate WP72. The reflector 77 reflects the one-time diffracted light Lb2 vertically so that the one-time diffracted light Lb2 travels the same path as the incident path. Incidentally, the one-time diffracted light Lb2 applied to the reflector 77 has already passed through the quarter-wave plate WP72, and the one-time diffracted light Lb2 reflected by the reflector 77 is the quarter-wave plate WP72. , The diffraction grating 71 is irradiated again with the polarization direction rotated by 90 °.
[0065]
The details of the light emitting / receiving composite unit 12 in the second embodiment and the operation example in the second embodiment are referred to the description of the first embodiment.
[0066]
In other words, the displacement detection device 70 according to the second embodiment using the reflective diffraction grating 71 can be easily adjusted precisely by packaging each member in the light emitting / receiving composite unit 12 into an integrated structure. In addition, it is not necessary to make a large arrangement space for the parts, and the entire displacement detector can be reduced in size and weight. In addition, by housing each member in the same housing member, it is possible to reduce the influence of environmental changes and changes over time, and to minimize deviations during adjustment. Can improve the reliability.
[0067]
Also in the second embodiment, the configuration in which the conversion of the light La from the light source 51 and the conversion of the light Ld from the light branching film 59 are shared by one phase plate 43 is adopted, so that dimensional management and easy Thus, it is possible to further reduce the manufacturing cost.
[0068]
Next, a method for manufacturing the light emitting / receiving composite unit 12 to which the present invention is applied will be described with reference to FIGS.
[0069]
First, in step S11, a light splitting portion 44 layer in which a plurality of light splitting portions 44 are connected, a phase plate 43 corresponding to the area of the plurality of light receiving and emitting composite units 12, and a polarizing portion 42 layer in which a plurality of polarizing portions 42 are connected. Is made. Then, the light splitting portion 44 layer, the phase plate 43, and the polarizing portion 42 layer are sequentially laminated to produce a laminated plate 81. When the laminated plate 81 is produced, the phase plate 43 may be laminated on the polarizing portion 42 layer, and the optical branching portion 44 layer may be further laminated thereon, or the optical branching portion 44 layer may be laminated thereon. Further, the phase plate 43 may be laminated, and the polarizing section 42 layer may be further provided thereon.
[0070]
Next, it transfers to step S12 and slices the produced laminated board 81 and divides | segments into plurality. Each of the laminated plates divided in step S12 corresponds to one light emitting / receiving composite unit 12.
[0071]
Next, the process proceeds to step S <b> 13, where the composite lens portion 41 is joined for each of the divided laminated plates 81, and the housing member 40 is joined to the joined composite lens portion 41.
[0072]
That is, in the manufacturing process of the light emitting / receiving composite unit 12 to which the present invention is applied, optical components having a size that is easy to process are bonded together, and then sliced to be divided into sizes that constitute the individual light receiving / emitting composite unit 12; Finally, since the composite lens unit 41 and the housing member 40 are bonded together and completed, the production process can be simplified and the manufacturing cost can be reduced.
[0073]
In particular, the light emitting / receiving composite unit 12 according to the present invention is packaged with each other to form an integrated structure, which facilitates precise position adjustment and eliminates the need for a large arrangement space for components, resulting in reduction in size and weight. There is an advantage in that it can be realized. For this reason, the above-mentioned manufacturing process can be adopted, and further miniaturization, cost reduction, and the like can be realized.
[0074]
In the above, the displacement detection apparatus of the 1st-2nd embodiment to which this invention is applied was demonstrated. In the displacement detection device of each embodiment, the diffraction gratings 11 and 71 in which the gratings are provided in parallel at a predetermined interval are used. In the present invention, a diffraction grating in which such a grating is provided in parallel is used. It is not necessary. For example, angle detection may be performed using a diffraction grating provided with a radial grating such as a rotary encoder.
[0075]
In the present invention, an amplitude type diffraction grating in which brightness and darkness are recorded and a phase type diffraction grating in which changes in refractive index and shape are recorded may be used, and the type of the diffraction grating is not limited.
[0076]
In the displacement detection device of each embodiment, the diffraction gratings 11 and 71 are attached to a movable part such as a machine tool, and the diffraction grating 11 moves in accordance with the movement of the movable part. Then, it is needless to say that the diffraction gratings 11 and 71 and the displacement detector need only move relatively.
[0077]
【The invention's effect】
As described above in detail, the displacement detection device and the light emitting / receiving composite unit according to the present invention are stacked such that the phase plate is sandwiched between the polarization unit and the light branching unit. This phase plate can convert light that is linearly polarized light into circularly polarized light and irradiate the polarized light separating unit. As a result, it is possible to freely select the polarization component of the light emitted from the light source as in the prior art without arranging the light source so that the polarization component is approximately 45 ° with respect to the polarization separation unit. Along with this, the problem that an extra area is required for component placement in the light emitting / receiving unit 12 can be solved, and a more compact configuration can be achieved. In addition, the phase plate can receive the combined light emitted from the light branching film and emit it to the polarizing section described above. Accordingly, it is sufficient that the polarization direction of each polarization part is set at 45 ° intervals, and the restrictions at the time of attaching the polarization part can be relaxed. As a result, the manufacturing process can be simplified and the manufacturing cost can be reduced. In addition, since this phase plate adopts a configuration in which the conversion of light from the light source and the conversion of light from the light branching film are shared by one phase plate, dimensional management is facilitated and manufacturing cost is further reduced. Is also possible.
[0078]
In addition, the displacement detection device according to the present invention is packaged so that the components are integrated into a single structure, thereby facilitating precise position adjustment and eliminating the need for a large arrangement space for the components. A reduction in size and weight can be achieved. In addition, by housing each member in the same housing member, it is possible to reduce the effects of environmental changes and changes over time, minimizing deviations during adjustment, and thus the reliability of the entire device. Can be increased.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a configuration of a displacement detection apparatus according to the present invention.
FIG. 2 is a perspective view of a diffraction grating used for displacement detection.
FIG. 3 is a diagram for explaining a case where a reflecting prism is used in the reflecting optical system.
FIG. 4 is a configuration diagram of a light receiving / emitting composite unit.
FIG. 5 is a diagram depicting a light emitting / receiving composite unit from above and below.
FIG. 6 is a diagram for explaining a displacement detection device using a reflection type diffraction grating.
FIG. 7 is a diagram for explaining a manufacturing method of a light emitting / receiving composite unit.
FIG. 8 is a perspective view of a conventional optical displacement measuring device.
FIG. 9 is a side view of a conventional optical displacement measuring device.
FIG. 10 is a perspective view of another conventional optical displacement measuring device.
FIG. 11 is a side view of another conventional optical displacement measuring device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Displacement detection apparatus, 11 Diffraction grating, 12 Light receiving / emitting composite unit, 13 Reflecting member, 14 Reflecting optical system, 26, 27 Reflector, WP1, WP2 1/4 wavelength plate, 40 Housing member, 41 Compound lens part, 42 Polarization Part, 43 phase plate, 44 light branching part, 51 light source, 52 light receiving element, 53,54 semiconductor substrate, 58 polarization separating part, 59 light branching film

Claims

A light source that emits light;
Polarized light that separates the light emitted from the light source into two lights having different polarization components, emits the light to an external optical system, and combines the two lights reflected from the external optical system to generate combined light A beam splitter ,
A light dividing means which divides the combined light generated by the above Kihenko beam splitter into a plurality,
Polarization means for transmitting only the predetermined polarization component of each of the divided combined light, and
A first portion disposed between the light source and the polarization beam splitter, and changing the polarization state of the light emitted from the light source to guide the light to the polarization beam splitter; and the light splitting means and the polarization means A phase plate that is disposed between and includes a second portion that changes the polarization state of the divided combined light, respectively.
E Bei a light receiving means for generating an interference signal by converting each photoelectric interference light transmitted through the polarizing means,
A light receiving / emitting composite unit comprising the polarizing unit, the phase plate, and the light splitting unit sequentially laminated .

The light receiving / emitting composite unit according to claim 1, wherein the phase plate is a quarter wave plate.

The light-receiving / emitting composite unit according to claim 2, wherein the polarization means transmits the polarization component of the divided combined light at intervals of 45 °.

The light emitted from the light emitting element and the light whose polarization state has been changed by the phase plate is separated into two and emitted to the external optical system, and the emitted light reflected from the external optical system is combined with each other, and the combined In the manufacturing method of the light receiving and emitting composite unit that detects the light that has been changed through the light receiving element by changing the polarization state by the phase plate,
A step of sequentially laminating a light splitting layer that divides the combined light into a plurality of layers, the phase plate, and a polarizing plate that transmits only a predetermined polarization component;
A cutting step of cutting the formed laminate plate in units of the light emitting and receiving units;
A composite lens portion for guiding light transmitted through the polarizing plate to the light receiving element is bonded to the cut laminated plate, and a light receiving / emitting portion including the light receiving element and the light emitting element is bonded to the bonded composite lens portion. A process for producing a light receiving / emitting composite unit.

In a displacement detection device that detects displacement in the grating vector direction for an inspection object provided with a reflective diffraction grating, based on an interference signal,
A light source that emits light;
A polarization beam splitter that separates and emits the light emitted from the light source into two lights having different polarization components ;
Two light emitted from the upper Kihenko beam splitter and focusing means for focusing the lattice plane of the diffraction grating,
Reflecting means for reflecting the two first diffracted lights obtained by diffracting the two lights emitted from the beam splitter by the diffraction grating, respectively;
Light splitting that synthesizes two second diffracted lights obtained by diffracting the first diffracted light reflected by the reflecting means by the diffraction grating to generate composite light, and divides the composite light into a plurality of parts Means,
Polarization means for transmitting only the predetermined polarization component of each of the divided combined light, and
A first portion disposed between the light source and the polarization beam splitter, and changing the polarization state of the light emitted from the light source to guide the light to the polarization beam splitter; and the light splitting means and the polarization means A phase plate that is disposed between and includes a second portion that changes the polarization state of the divided combined light, respectively.
The interference light transmitted through the polarizing means converts each photoelectric example Bei the light receiving means for generating the interference signal,
A displacement detection device comprising: the polarizing means, the phase plate, and the light splitting means stacked in order .

6. The displacement detection device according to claim 5 , wherein the phase plate is a quarter-wave plate.

The phase plate is further disposed between said light splitting means and said polarizing means, the polarization state of the divided composite light by respective changes in claim 5, wherein the leading to the polarizing means Displacement detector.

The light source, the polarizing beam splitter, the phase plate, the imaging means, the light splitting means, the polarizing means, and the light receiving means are arranged in the same package and configured as an independent unit. The displacement detection device according to claim 5 .

In a displacement detection device that detects displacement in the direction of a grating vector based on an interference signal for an inspection object on which a transmission type diffraction grating is arranged,
A light source that emits light;
A polarization beam splitter that separates and emits the light emitted from the light source into two lights having different polarization components ;
Upper SL and reflecting means two light emitted from the beam splitter is respectively reflected two first diffracted light obtained is diffracted by the diffraction grating,
Light splitting that synthesizes two second diffracted lights obtained by diffracting the first diffracted light reflected by the reflecting means by the diffraction grating to generate composite light, and divides the composite light into a plurality of parts Means,
Polarization means for transmitting only the predetermined polarization component of each of the divided combined light, and
Disposed between the upper Symbol light source and the polarization beam splitter, a first portion by changing the polarization state of light emitted from the light source leads to the polarization beam splitter, and said light splitting means and said polarizing means A phase plate including a second portion disposed between the second portions for changing the polarization state of the divided combined light, and
The interference light transmitted through the polarizing means converts each photoelectric example Bei the light receiving means for generating the interference signal,
A displacement detection device comprising: the polarizing means, the phase plate, and the light splitting means stacked in order .

The displacement detection device according to claim 9 , wherein the phase plate is a ¼ wavelength plate.

The phase plate is further disposed between said light splitting means and said polarizing means, the polarization state of the divided composite light by respective changes in claim 9, wherein the lead to the polarizing means Displacement detector.

The light source, the polarizing beam splitter, the phase plate, the light splitting means, the polarizing means, and the light receiving means are arranged in the same package and configured as an independent unit. Item 10. The displacement detection device according to Item 9 .