JP2004020940A - Shape variable mirror and optical disk information input and output device - Google Patents

Shape variable mirror and optical disk information input and output device Download PDF

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JP2004020940A
JP2004020940A JP2002175893A JP2002175893A JP2004020940A JP 2004020940 A JP2004020940 A JP 2004020940A JP 2002175893 A JP2002175893 A JP 2002175893A JP 2002175893 A JP2002175893 A JP 2002175893A JP 2004020940 A JP2004020940 A JP 2004020940A
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mirror
detecting means
temperature detecting
deformable
shape
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JP2002175893A
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Japanese (ja)
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Hiroyoshi Shoji
庄子　浩義
Masaki Hiroi
廣居　正樹
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Ricoh Co Ltd
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Ricoh Co Ltd
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<P>PROBLEM TO BE SOLVED: To provide a shape variable mirror having a temperature detecting means capable of substantially accurately measuring ambient temperature, nearly free from distortion of initial plane shape, and having variable shape of a mirror surface of a mirror part and to provide an optical disk information input and output device provided with an optical pickup device having the shape variable mirror. <P>SOLUTION: The shape variable mirror wherein the shape of the mirror plane of the mirror part is variable has the temperature detecting means 10 detecting temperature around the shape variable mirror. The temperature detecting means 10 is provided at a part where the shape of the mirror plane is not changed. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、鏡部の鏡面の形状を変化させる形状可変鏡、及び光ピックアップ装置を備えた光ディスク情報入出力装置に関する。
【０００２】
【従来の技術】
一般に光ディスクを用いた光ディスク情報入出力装置としてＣＤやＤＶＤなどがある。ＤＶＤなどはＣＤに比べ記録密度が高い為、情報の読み書きに関する条件がより厳しくなっている。例えば光ピックアップ装置の光軸とディスク面は垂直であることが理想であるが、実際には光ディスクが樹脂製である為、ディスク面はかなりうねりを持っていて、これを回転させると光ピックアップ装置の光軸とディスク面は常には垂直ではなく、ディスク面が光軸に対して傾きを持つことがある（以下、光軸に対するディスク面の傾きをチルトと表現する）。またＣＤ、ＤＶＤ共に光ディスクにおいては、図１に示すように、記録層１０８が樹脂層１０２ａ、１０２ｂを介在している為、チルトすなわちディスク面が傾くとレーザー光の光路が曲げられてコマ収差が発生し、図１の１０３ａ、１０３ｂに示すように光ディスク上に正しくスポットを絞れなくなる。このコマ収差が許容される量よりも大きくなると、情報を正しく読み書きできなくなるという不具合が生じる。
【０００３】
チルトにより発生する収差を低減する手段としては、対物レンズと記録層との間にある樹脂層の厚さを薄くする方法がある。実際に図１（ｂ）に示すようなＤＶＤにおいて、対物レンズ１０１ｂと記録層１０８との間の樹脂層１０２ｂの厚さを、図１（ａ）に示すＣＤの場合に比較して半分にしてあるのは、コマ収差の低減を意図したものである。しかしこの方法では、ＤＶＤよりも記録密度を高くしようとした場合には樹脂層の厚さをさらに薄くしてチルトの影響を低減することになるが、今度は光ディスク上にゴミや傷が付いた場合に信号を正しく読み書きできなくなるという不具合が生じる。この為、アクチュエータによって光ピックアップ装置の光軸を傾けて、チルトに対応しているのが現状である。
【０００４】
チルトによる影響を光学的に補正する手段として、特開平１０−７９１３５に記載の液晶板を用いる方法がある。また圧電素子を用いたチルトによるコマ収差などの補正手段として、特開平５−１４４０５６に記載のレーザー光の光路中に透明圧電素子を用いる方法や、特開平５−３３３２７４に記載の複数のアクチェータを利用した形状可変鏡を用いる方法などが提案されている。
【０００５】
しかしながら、特開平１０−７９１３５のように液晶板を用いて位相を制御することでコマ収差を補正する方法では、レーザーが液晶板を通過するために光量が減衰して書き込みに必要なエネルギーを得ることが困難であり、また液晶の特性から、特にタンジェンシャルチルトの制御に要求される高周波動作に使用することは困難である。
【０００６】
また、特開平５−１４４０５６のように単独の透明圧電素子で必要な厚さの変化を得るためには、実際には高電圧が必要となり光ピックアップ装置などに用いるには現実的ではない。
さらに、特開平５−３３３２７４のように形状可変鏡の鏡自体を積層型圧電素子で変形させ位相制御する方法は、光ピックアップ装置などの小さい部品に用いるには配線などの考慮がされておらず、複雑になり、かつ組み付けコストも高くなる。また、配線などの問題が解決できたとしても、積層型圧電素子を小型化することは、技術的にもコスト的にも困難である。
【０００７】
上述した従来技術の問題点を解決する方法として、ユニモルフ型又はバイモルフ型の圧電素子を使用した形状可変鏡で、チルトなどにより発生する波面収差（主としてコマ収差）を低減する方法が考えられる。これは例えば、図２に示すような鏡面の形状が可変な形状可変鏡（以後、通常構造の形状可変鏡と呼ぶ）である。ここで図２は、形状可変鏡の断面図である。この形状可変鏡において、鏡基板６の片面に鏡材１、鏡材１の鏡面側を下と表現すると、鏡基板６の上には、配線４ｂ、その上には電極４ａ、その上に圧電極性が一方向の圧電素子２、さらにその上に二つの電極５ａがある。鏡基板６は、凹形状の鏡固定用部材８によって鏡固定部３で固定され、鏡固定用部材８には、配線４ｂとワイヤを介して接続する配線４ｃ、電極５ａとワイヤを介して接続する配線５ｃが設けられている。ここで、配線４ｃ及び二つの配線５ｃを介して電極４ａと電極５ａとの間に電位差を与えると、圧電素子２がその電位差に応じて伸縮し、鏡基板６及び鏡材１を含む鏡部の鏡面の形状を変形させる。なお、二つの電極５ａの圧電極性を変えたり、二つの電極５ａに印加する電圧を変えることで、圧電素子２の伸縮を調節して鏡部の鏡面形状を制御することができる。
【０００８】
また、図３（ａ）、（ｂ）は、別の形態の形状可変鏡（以後、薄膜構造と呼ぶことにする）を示す図であり、（ａ）は、配線４ｃ、５ｃを有する鏡固定用部材８を取り除いて反射膜１と反対側から見た形状可変鏡の平面図であり、（ｂ）は、（ａ）のＡ−Ａ’方向における形状可変鏡の断面図であり、（ｃ）は、形状可変鏡における鏡面形状の変化を説明する図である。図３（ａ）、（ｂ）に示すように、この薄膜構造の形状可変鏡は、鏡面側を下側、鏡面と反対側を上側と呼ぶことにすると、鏡基板６の下には反射膜１があり、鏡基板６の上には絶縁膜７があり、その上には配線４ｂ、５ｂがある。鏡基板６は周辺部に厚い凸部１４を有している。配線４ｂ上には配線４ｂと接続している二つの電極４ａがあり、電極４ａの上には圧電素子２が接着されており、さらに圧電素子２の上に二つの電極４ａと対向する二つの電極５ａがある。鏡基板６の周辺に形成された配線４ｂと電極４ａに接続している圧電素子２の下にある配線４ｂとの間、及び鏡基板６の周辺に形成された配線５ｂと圧電素子２上に形成された電極５ａとの間には、それぞれ接続用のワイヤがある。ここで、ここで、反射膜、鏡基板、絶縁膜、配線を含む部分を鏡部と定義する。また、図３の形状可変鏡においては、鏡部の変形を容易とする為に、鏡部にスリットを設けてある。ここで、圧電素子及び電極を含む部分を圧電基板部と定義する。圧電基板部及びワイヤを有する鏡部は、配線４ｃ、５ｃを有する鏡固定用部材８の鏡固定部３に、鏡部周辺の厚い凸部１４で固定されている。図３に示す薄膜構造の形状可変鏡は、鏡基板６の鏡面と反対側の部分をエッチングして、鏡基板６の厚さを薄くしており、低電圧で鏡部の鏡面形状を変化させることができる。
【０００９】
このような薄膜構造の形状可変鏡において、配線４ｂ、従って二つの電極４ａを接地し、配線５ｂから２つの電極５ａの片方にプラスの電圧、他方にマイナスの電圧を印加したとする。鏡基板６自体は電圧を印加しても伸縮しないが、圧電素子２は、電圧を印加すれば伸縮する。電極５ａにプラスの電圧を印加した場合に、電極５ａの設置された部分の圧電素子２が縮むとすると、マイナスの電圧を印加した場合には、その部分の圧電素子２は伸びることとなり、電極５ａにプラスの電圧を印加した部分の鏡面は凸面に、電極５ａにマイナスの電圧を印加した部分の鏡面は凹面になる。その結果、図３に示す形状可変鏡の鏡面形状は、図３（ｃ）に示すように、Ａ−Ａ’方向に鏡面の中心を挟んで凸面と凹面を有し、Ａ−Ａ’方向の断面は鏡面の中心が節に相当する波型の形状になる。なお、図３（ｃ）の横軸は、図３に示す形状可変鏡のＡ−Ａ’方向の軸、縦軸は、Ａ−Ａ’方向の断面における鏡面形状の変化量である。また２つの電極５ａに前述と逆の電圧を印加した場合には、図３（ｃ）に示す形状と逆の波型の形状になる。なお、二つの電極５ａの圧電極性を変えたり、二つの電極５ａに印加する電圧を変えることで、圧電素子２の伸縮を調節して鏡部の鏡面形状を制御することができる。
【００１０】
このような形状可変鏡を、光ディスク情報入出力装置における光ピックアップ装置の光軸上に設置し、鏡面の形状を制御することによって、チルトによるコマ収差を低減することが可能になる。光ディスク情報入出力装置において、光ディスクにチルト、即ちレーザー光の光軸に対して垂直な方向を基準とした光ディスクの傾き、が生じると、光ディスクから反射して戻ってきたレーザー光の波面は乱れコマ収差が発生する。チルトした光ディスクから戻ってきて形状可変鏡の鏡面に入射するレーザー光の波面収差は、レーザー光の光束の断面に対して図４に示すような等高線で表わされる。ここで、レーザーの光束の断面において、光ディスクがチルトした方向に対応する方向が図４のＡ−Ａ’方向である。すなわちＡ−Ａ’方向に沿って符号が変わる波面収差（コマ収差）が発生する。
【００１１】
このようなチルトにより発生する波面収差を低減する為に、図３に示すような形状可変鏡を、図３（ａ）のＡ−Ａ’方向と図４のＡ−Ａ’方向とを一致させて光ピックアップ装置の光軸上に設置する。前述した形状可変鏡の動作により、Ａ−Ａ’方向について凸面と凹面とが生じるように、鏡面の形状を適切に制御すれば、チルトによる波面収差（コマ収差）の補正又は低減が可能となる。ここで簡単の為に図４におけるＡ−Ａ’方向についてのみ注目して、レーザー光の波面収差の低減を、図５（ａ）乃至（ｃ）を用いて説明する。図５（ａ）は、光ディスクがチルトした場合に発生するレーザー光の波面収差に関する図４のＡ−Ａ’方向の波面収差図である。ここで、図５（ａ）乃至（ｃ）における縦軸は波面収差であり、図３における横軸は、図４のＡ−Ａ’方向の軸（即ち形状可変鏡のＡ−Ａ’方向の軸）である。なお、光ディスクがチルトせずレーザー光の光軸に対し垂直であれば、図５（ａ）に示すような波面収差は発生せず、波面は横軸に一致する。図５（ｂ）は、形状可変鏡を故意に収差を発生させるように動作させ、無収差の光を形状可変鏡に照射した場合の反射光の波面収差を示した図である。今、光ディスクにチルトが生じ、光ディスクからの反射光の波面収差が図５（ａ）であったとして、光ディスクにチルトが生じていない場合に形状可変鏡で反射した光の波面収差が図５（ｂ）となるように形状可変鏡の鏡面の形状を制御する。この場合には、図５（ａ）と図５（ｂ）の波面収差が互いに相殺する関係となって、形状可変鏡からの反射光の波面収差は、図５（ｃ）のようになり、図５（ａ）と比較して波面収差を低減させることができる。
【００１２】
【発明が解決しようとする課題】
ここで、上述したような形状可変鏡においては、圧電素子に電圧を印加していない状態における鏡部の鏡面形状（以下、簡単のために初期平面形状と呼ぶことにする）が、周囲の温度変化によって変動することが知られている。特に、図３に示す薄膜構造の形状可変鏡では、鏡基板６の厚さが薄いため、温度変化による鏡面形状の変動は、顕著となる。すなわち、形状可変鏡の鏡部における鏡面形状が変化する部分は、反射膜１、鏡基板６、絶縁膜７、配線４ｂなどを含むと共に、電極４ａ、５ａ、配線４ｂ、接着剤で取り付けられた圧電素子２を備えており、これらの構成要素は、それぞれ異なる熱膨張係数を有している。よって、これらの構成要素は、周囲の温度変化によって別々に伸縮するため、鏡部の初期鏡面形状は、全体として歪むことになる。
【００１３】
従って、周囲の温度変化が起こっても形状可変鏡の初期平面形状を平面に保つために、形状可変鏡の初期平面形状の温度変化を補償する必要がある。形状可変鏡の初期平面形状の温度変化を補償する方法として、周囲の温度を温度検知手段で随時測定し、測定した温度に基づいて圧電素子にオフセット電圧を印加することで、形状可変鏡の初期平面形状の歪みを補正する方法がある。
【００１４】
温度検知手段としては、市販の温度検知手段を使用することができる。このような温度検知手段を、温度補償が必要とされる、形状可変鏡における鏡面形状の変化する部分の近傍に取りつけてもよい。しかしながら、光ディスク情報入出力装置の光ピックアップ装置などに設置する小型の形状可変鏡に対する温度検知手段の取り付けは、温度検知手段を取り付ける場所を確保しなければならないという問題がある。このため、薄膜で構成される温度検知手段を、形状可変鏡の鏡部と一体に作製することが望ましい。このような薄膜で構成される温度検知手段は、温度変化によって抵抗値が変動する金属薄膜抵抗体と金属薄膜抵抗体を覆う絶縁膜を含む。
【００１５】
しかしながら、形状可変鏡、特に薄膜構造の形状可変鏡、の鏡部における鏡基板は、鏡部の鏡面形状を効率良く変形するために、非常に薄く形成されている（例えば、５０μｍ〜２００μｍ）。このため、薄膜で構成される温度検知手段を、単純に鏡部と一体に形成すると、温度検知手段における金属薄膜抵抗体や絶縁膜の膜応力による影響で、鏡部の初期鏡面形状が歪むと共に周囲の温度変化による鏡部の初期平面形状の変動がさらに強調される場合もある。また、薄膜で構成される温度検知手段において、金属薄膜抵抗体の材料を白金（Ｐｔ）とすると、Ｐｔの金属薄膜抵抗体は、一般的な酸化シリコン（ＳｉＯ２）の絶縁膜との密着性が悪い。よって、ＳｉＯ２の絶縁膜を通じたＰｔの金属薄膜抵抗体への熱伝導が不十分であり、Ｐｔの金属薄膜抵抗体における抵抗の変化による温度測定が不正確となり、温度検知手段としての信頼性を確保するのことが困難となる。さらに、形状可変鏡の鏡部における鏡面形状が変化する部分の近傍に温度検知手段内の金属薄膜抵抗体を配置すると、圧電素子に電圧を印加して鏡部の鏡面形状を変化させるとき、鏡面形状の変化によって金属薄膜抵抗体に応力が発生して、その抵抗値が変動し、周囲の温度を正確に測定することができなくなる。
【００１６】
本発明は、上記問題に鑑みなされたものであり、周囲の温度を実質的に正確に測定することができる温度検知手段を有し、初期平面形状の歪みが少ない、形状可変鏡及び該形状可変鏡を有する光ピックアップ装置を備えた光ディスク情報入出力装置を提供することを目的とする。
【００１７】
【課題を解決するための手段】
請求項１記載の発明は、鏡部の鏡面の形状が可変な形状可変鏡において、該形状可変鏡の周囲の温度を検知する温度検知手段を有し、該温度検知手段は、前記鏡部の前記鏡面の形状が変化しない部分に設けられることを特徴とする。
【００１８】
請求項１記載の発明によれば、該形状可変鏡の周囲の温度を検知する温度検知手段を有し、該温度検知手段は、前記鏡部の前記鏡面の形状が変化しない部分に設けられるので、周囲の温度を実質的に正確に測定することができる温度検知手段を有し、初期平面形状の歪みが少ない、形状可変鏡を提供することができる。
【００１９】
請求項２記載の発明は、鏡部の鏡面の形状が可変な形状可変鏡において、該形状可変鏡の周囲の温度を検知する温度検知手段を有し、該温度検知手段は、前記鏡部の前記鏡面の形状が変化しない部分に一体に設けられることを特徴とする。
【００２０】
請求項２記載の発明によれば、該形状可変鏡の周囲の温度を検知する温度検知手段を有し、該温度検知手段は、前記鏡部の前記鏡面の形状が変化しない部分に一体に設けられるので、周囲の温度を実質的に正確に測定することができる温度検知手段を有し、初期平面形状の歪みが少ない、形状可変鏡を提供することができると共に、温度検知手段を確実に形状可変鏡に設けることができる。
【００２１】
請求項３記載の発明は、請求項１又は２記載の形状可変鏡において、前記鏡部の鏡面の形状は、前記鏡部の前記鏡面と反対側に設けられた圧電素子の伸縮によって変化させられ、前記温度検知手段は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分及び前記圧電素子が設けられる部分の間、に配置されることを特徴とする。
【００２２】
請求項３記載の発明によれば、前記鏡部の鏡面の形状は、前記鏡部の前記鏡面と反対側に設けられた圧電素子の伸縮によって変化させられ、前記温度検知手段は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分及び前記圧電素子が設けられる部分の間、に配置されるので、圧電素子の伸縮により鏡部の鏡面の形状を変化させても、温度を高い精度で測定でき、長期信頼性が確保された温度検知手段を有する形状可変鏡を提供することができる。
【００２３】
請求項４記載の発明は、請求項１又は２記載の形状可変鏡において、前記鏡部の鏡面の形状は、前記鏡部の前記鏡面と反対側に設けられた圧電素子の伸縮によって変化させられ、前記温度検知手段は、前記鏡部の前記鏡面側の、前記鏡部の前記鏡面と反対側で前記鏡部を支持する部材が前記鏡部と接触する部分及び前記鏡部の前記鏡面と反対側で前記圧電素子が設けられる部分の間、に配置されることを特徴とする。
【００２４】
請求項４記載の発明によれば、前記鏡部の鏡面の形状は、前記鏡部の前記鏡面と反対側に設けられた圧電素子の伸縮によって変化させられ、前記温度検知手段は、前記鏡部の前記鏡面側の、前記鏡部の前記鏡面と反対側で前記鏡部を支持する部材が前記鏡部と接触する部分及び前記鏡部の前記鏡面と反対側で前記圧電素子が設けられる部分の間、に配置されるので、圧電素子の伸縮により鏡部の鏡面の形状を変化させても、温度を高い精度で測定でき、長期信頼性が確保された温度検知手段を有する形状可変鏡を提供することができると共に、温度検知手段を容易に製造することができる。
【００２５】
請求項５記載の発明は、請求項１又は２記載の形状可変鏡において、前記温度検知手段は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分、に配置されることを特徴とする。
【００２６】
請求項５記載の発明によれば、前記温度検知手段は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分、に配置されるので、
温度を高い精度で測定でき、長期信頼性が確保された温度検知手段を有する形状可変鏡を提供することができると共に、温度検知手段の膜応力による形状可変鏡の初期鏡面形状の歪みを除去することができる。
【００２７】
請求項６記載の発明は、請求項１又は２記載の形状可変鏡において、前記温度検知手段は、前記鏡部の前記鏡面側の、前記鏡部の前記鏡面と反対側で前記鏡部を支持する部材が前記鏡部と接触する部分、に配置されることを特徴とする。
【００２８】
請求項６記載の発明によれば、前記温度検知手段は、前記鏡部の前記鏡面側の、前記鏡部の前記鏡面と反対側で前記鏡部を支持する部材が前記鏡部と接触する部分、に配置されるので、製造が容易であり、温度を高い精度で測定でき、長期信頼性が確保された温度検知手段を有する形状可変鏡を提供することができると共に、温度検知手段の膜応力による形状可変鏡の初期鏡面形状の歪みを除去することができる。
【００２９】
請求項７記載の発明は、請求項４又は６記載の形状可変鏡において、前記鏡部は、前記鏡部の前記鏡面側に前記形状可変鏡に入射する光を反射する反射膜を含み、前記温度検知手段は、前記鏡部の前記反射膜が設けられてない部分に配置されることを特徴とする。
【００３０】
請求項７記載の発明によれば、前記鏡部は、前記鏡部の前記鏡面側に前記形状可変鏡に入射する光を反射する反射膜を含み、前記温度検知手段は、前記鏡部の前記反射膜の設けられてない部分に配置されるので、反射膜の膜応力による温度検知手段の測定精度の低下を防止し、正確に温度を測定することができる温度検知手段を有する形状可変鏡を提供することができる。
【００３１】
請求項８記載の発明は、請求項３又は５記載の形状可変鏡において、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触しない部分に対する凸部であり、前記温度検知手段は、該温度検知手段を駆動する電圧を印加する電極を有し、前記温度検知手段の前記電極に接続される配線は、少なくとも前記凸部に設けられ、前記配線の前記凸部における幅は、前記電極の幅よりも広いことを特徴とする。
【００３２】
請求項８記載の発明によれば、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触しない部分に対する凸部であり、前記温度検知手段は、該温度検知手段を駆動する電圧を印加する電極を有し、前記温度検知手段の前記電極に接続される配線は、少なくとも前記凸部に設けられ、前記配線の前記凸部における幅は、前記電極の幅よりも広いので、配線を凸部に容易に形成することができると共に、温度検知手段に接続する配線の凸部における抵抗値の増加を抑制し、不正抵抗が少なく、温度測定の感度が高い温度検知手段を有する形状可変鏡を提供することができる。
【００３３】
請求項９記載の発明は、請求項１乃至８いずれか１項記載の形状可変鏡において、前記温度検知手段は、白金からなる薄膜の抵抗体、及び前記抵抗体の少なくとも一部分を覆う五酸化二タンタル又は窒化シリコンからなる絶縁層を含むことを特徴とする。
【００３４】
請求項９記載の発明によれば、前記温度検知手段は、白金からなる薄膜の抵抗体、及び前記抵抗体の少なくとも一部分を覆う五酸化二タンタル又は窒化シリコンからなる絶縁層を含むので、特に抵抗体と絶縁層の密着性が良好であり、温度を精度よく正確に測定できる温度検知手段を有する形状可変鏡を提供することができる。
【００３５】
請求項１０記載の発明は、請求項９記載の形状可変鏡において、前記抵抗体の抵抗値は、１ｋΩ乃至１０ｋΩであることを特徴とする。
【００３６】
請求項１０記載の発明によれば、前記抵抗体の抵抗値は、１ｋΩ乃至１０ｋΩであるので、適切な温度測定に対する感度と適切な消費電力を有する温度検知手段を備えた形状可変鏡を提供することができる。
【００３７】
請求項１１記載の発明は、光ピックアップ装置を備える光ディスク情報入出力装置において、請求項１乃至１０いずれか１項記載の形状可変鏡を有することを特徴とする。
【００３８】
請求項１１記載の発明によれば、請求項１乃至１０いずれか１項記載の形状可変鏡を有するので、周囲の温度を実質的に正確に測定することができる温度検知手段を有し、初期平面形状の歪みが少ない、形状可変鏡を有する光ピックアップ装置を備えた光ディスク情報入出力装置を提供することができる。
【００３９】
【発明の実施の形態】
次に、本発明の実施の形態について図面と共に説明する。
【００４０】
まず、本発明における第一の実施形態を図６と共に説明する。図６は、本発明の第一の実施形態における形状可変鏡を示し、（ａ）は、本発明の形状可変鏡の鏡面と反対側から見た平面図である。ただし、簡単のために鏡固定用部材や一部の配線やワイヤを省略して描いてある。また、図６（ｂ）、（ｃ）は、本発明の形状可変鏡に設けられる温度検知手段の断面図である。
【００４１】
本実施形態の形状可変鏡の基本的な構成は、図２に示す通常構造の形状可変鏡と同様である。図６（ａ）に示すように、本実施形態の形状可変鏡においては、鏡面側を下側、鏡面と反対側を上側と呼ぶことにすると、Ｓｉで形成された鏡基板６の下には鏡材があり、鏡基板６の上には配線４ｂがある。配線４ｂ上には配線４ｂと接続している電極があり、その電極の上には圧電素子２が接着されており、さらに圧電素子２の上に上述の二つの電極と対向する二つの電極５ａがある。
【００４２】
図２に示す従来の形状可変鏡と異なり、本実施形態の形状可変鏡においては、鏡基板６の一部に温度検知手段１０が形成されている。具体的には、温度検知手段１０を、鏡基板６における鏡固定部３（鏡固定用部材で固定される部分）の近傍に形成している。ここで、圧電素子に電圧を印加して鏡部の鏡面形状を変化させたとき、鏡面形状が大きく変化する部分は、電極５ａが配置されている図６（ａ）の矢印部分である。よって、温度検知手段１０を鏡基板６の鏡固定部３の近傍に形成することで、温度検知手段１０は、圧電素子に電圧を印加したときの鏡面形状の変化に起因する内部応力の発生を回避することができる。よって、温度検知手段における金属薄膜抵抗体の抵抗値の変化を防ぎ、周囲の温度を実質的に正確に測定することができる。
【００４３】
本実施形態において使用される温度検知手段１０は、図６（ｂ）又は図６（ｃ）に示すように、温度変化によって抵抗値が変動する金属で形成される金属薄膜抵抗体１２、金属薄膜抵抗体１２を鏡基板６に密着させる、絶縁膜で形成される密着層１１、及び密着層１１と共に金属薄膜抵抗体１２を覆い、金属薄膜抵抗体１２を保護する保護膜１３を含む。
【００４４】
本実施形態において使用される温度検知手段１０の製造方法は、まず、ＳｉＯ２である絶縁膜の表面を、酸素（Ｏ２）プラズマ処理、バックスパッタ処理、又はアルゴン（Ａｒ）やシリコン（Ｓｉ）等のイオン注入によって処理し、金属薄膜抵抗体１２との密着性を向上させた密着層１１を製膜する。密着層１１と金属薄膜抵抗体１２との密着性をさらに向上させるために、図６（ｃ）に示すように、密着層１１の表面に凹部を形成し、その凹部の内部に金属薄膜抵抗体１２を形成することが好ましい。
【００４５】
次に、主としてスパッタ法により金属薄膜抵抗体１２を密着層１１上に形成する。この金属薄膜抵抗体１２の薄膜は、粒の集合体であり、これらの粒同志の界面（粒界）には、不正抵抗が存在する。ここで、金属薄膜抵抗体１２の薄膜に応力（膜変位）が発生すると、この粒界の不正抵抗が増大する。よって、金属薄膜抵抗体１２の薄膜を、温度変化に検知に使用する場合には、金属薄膜抵抗体１２の薄膜に応力が発生しないようにする必要がある。すなわち、圧電素子２に電圧を印加して形状可変鏡の鏡面形状を変化させる際には、凹凸形状などの鏡面形状の変動によって金属薄膜抵抗体１２に応力が発生することを避けるために、鏡部における鏡面形状の変化する部分に温度検出手段１０を形成しないことが望ましい。加えて、形状可変鏡の鏡面形状の変化によって、金属薄膜抵抗体１２にストレスマイグレーションが発生する可能性があるため、温度検知手段１０の温度測定における長期信頼性を確保するためにも、鏡部における鏡面形状の変化する部分に温度検出手段１０を形成することは避けるべきである。
【００４６】
最後に、金属薄膜抵抗体１２及び密着層１１上に絶縁膜からなる保護膜１３を形成して、金属薄膜抵抗体１２を密着層１１と保護膜１２で覆い、温度検知手段１０が完成する。
【００４７】
本実施形態においては、温度検知手段１０を鏡基板６の一部分においてのみ形成しているため、形状可変鏡の反射膜は、温度検知手段１０を構成している密着層１１、金属薄膜抵抗体１２、及び保護膜１３の膜応力による影響を実質的に受けない。よって、本実施形態の形状可変鏡においては、形状可変鏡の初期鏡面形状が歪むことや、周囲の温度変化による鏡部の初期平面形状の変動が強調されることを実質的に防止することができる。
【００４８】
次に、本発明における第二の実施形態を図６、図７と共に説明する。
【００４９】
本実施形態における形状可変鏡は、前述の第一の実施形態における形状可変鏡と同様の構成を有するが、金属薄膜抵抗体１２をＰｔ薄膜で作製し、密着層１１及び保護膜１３を、それぞれ窒化シリコン（Ｓｉ３Ｎ４）膜又は五酸化二タンタル（Ｔａ２Ｏ５）膜で作製している。
【００５０】
金属薄膜抵抗体１２であるＰｔ薄膜は、スパッタ法で成膜する。スパッタ条件を変えることによって金属薄膜抵抗体１２の抵抗温度係数（ＴＣＲ）をある程度自由に変化させることができるので、温度変化に対する抵抗値の変化の大きい、すなわち感度の高い、金属薄膜抵抗体１２を作製することができる。例えば、金属薄膜抵抗体１２を製膜するとき、スパッタ装置の電力を下げると共に鏡基板６の温度を高く設定することで、高い抵抗温度係数を有する金属薄膜抵抗体を得ることができる。このようにして、温度変化に対する抵抗値の変化が大きい、高感度な金属薄膜抵抗体１２を形成する。
【００５１】
金属薄膜抵抗体１２がＰｔ薄膜である場合において、温度検知手段１０の密着層１１及び保護膜１３にＳｉＯ２膜を使用すると、ＳｉＯ２膜は、Ｐｔとの密着性が悪いため、温度検知手段１０による温度測定の信頼性を確保することが困難である。密着層１１及び保護膜１３の金属薄膜抵抗体１２との密着性を向上させるためには、密着層１１及び保護膜１３としてＳｉＯ２膜の代わりにＳｉ３Ｎ４膜又はＴａ２Ｏ５膜を用いることが望ましい。また、金属薄膜抵抗体１２としてのＰｔ薄膜を密着層１１に製膜する前に、密着層１１にバックスパッタ処理を施すことで密着層１１と金属薄膜抵抗体１２との密着性をさらに向上させることができる。
【００５２】
ここで、本実施形態における温度検知手段１０の製造方法について説明する。まず、鏡基板６の鏡面と反対側の面に、密着層１１を形成するための厚さ０．３μｍのＴａ２Ｏ５膜をスパッタ法により成膜し、連続して金属薄膜抵抗体１２を形成するための厚さ０．２μｍのＰｔ薄膜をスパッタ法により成膜した。次に、Ｐｔ薄膜から金属薄膜抵抗体１２を形成するためのマスク材として０．２μｍのＴａ２Ｏ５膜を成膜した。このマスク材をフォトリソグラフ法によって所望の金属薄膜抵抗体１２の形状（金属薄膜抵抗体１２の抵抗値を測定する手段を接続する部分、即ちボンディングパッド、を含む）に合わせてパターニングし、次にバックスパッタ処理を施すことにより、Ｐｔ薄膜を所望の金属薄膜抵抗体の形状にエッチングした。その後、保護膜１３として、厚さ０．３μｍのＴａ２Ｏ５膜をスパッタ法により成膜した。次に、フォトリソグラフ法によって、密着層１１及び保護膜１３を形成するためのＴａ２Ｏ５膜を、鏡基板６における温度検知手段１０を形成する部分（以下、簡単のために温度検知手段形成領域と呼ぶことにする）の形状にパターニングする。最後に、密着層１１及び保護膜１３を形成するためのＴａ２Ｏ５膜における温度検知手段形成領域以外の部分の全てを、エッチングによって除去することで、本実施形態における温度検知手段１０が完成する。このパターニング及びエッチングの際には、同時に、保護膜１３に、金属薄膜抵抗体１２のボンディングパッドを金属薄膜抵抗体１２の抵抗値を測定する手段を接続するための穴を形成する（ボンディングパッドの窓開け）。
【００５３】
次に、本実施形態における温度検知手段１０の動作を、図７と共に具体的に説明する。図７は、本実施形態における温度検知手段１０及び金属薄膜抵抗体１２の形態を示す。
【００５４】
本実施形態において、Ｐｔ薄膜の成膜条件として、鏡基板の温度を３００℃に保つと共にスパッタ装置の電力２００Ｗに設定したことで、３２００ｐｐｍ／℃のＴＣＲを有するＰｔ薄膜が得られた。図７に示すように、ボンディングパット（金属薄膜抵抗体１２の両端部分）を除く金属薄膜抵抗体１２を線形に形成し、その寸法を、線幅４μｍ、線の長さ３０ｍｍ、膜厚０．２μｍとすれば、金属薄膜抵抗体１２の全体の抵抗値は、約５０００Ωとなる。ここで、ボンディングパッドは、通常、金属薄膜抵抗体１２のボンディングパット以外の部分より大きいので、ボンディングパッドの抵抗値は無視できる。また、ＴＣＲが３２００ｐｐｍ／℃であるので、温度が１℃だけ変化すると、抵抗値は、約１６Ωだけ変化する。例えば、この金属薄膜抵抗体に０．５ｍＡの定電流を流すとすれば、この金属薄膜抵抗体の電圧は、２．５Ｖになり、温度が１℃だけ変化すると、電圧の変化量は、約８ｍＶとなる。この電圧の変化量が、温度の変化に対応するので、金属薄膜抵抗体１２に定電流を流して電圧を測定すれば、周囲の温度を測定することができる。この抵抗値は、単なる一つの例であり、温度検知手段１０やボンディングパッドの大きさによる制限の下で、金属薄膜抵抗体１２の形状、即ち長さや断面積、をある程度自由に設計することができる。よって、金属薄膜抵抗体の感度（温度変化に対する電圧変化量）の向上や配線抵抗等の不正抵抗による電圧測定精度の低下を考慮して、ある程度自由に設計することができる。
【００５５】
また図７に示すように、金属薄膜抵抗体１２の面積は、ボンディングパッドを合わせても７ｍｍ×０．１５ｍｍのように、かなり小さく作製すりことができ、この温度検知手段１０を、鏡面と反対側における鏡部の鏡面形状の変化が少ない部分に設置することで、温度検知手段の温度測定における長期信頼性を得ることができる。この温度検知手段１０の大きさは、単なる一つの例であり、金属薄膜抵抗体１２の形状における折り返しの数を多くすることで、温度検知手段１０の長さを短くできる。これにより、形状可変鏡の鏡部の大きさに適合した温度検知手段１０をある程度自由に設計することができる。
【００５６】
次に、本発明における第三の実施形態を図８と共に説明する。
【００５７】
図８（ａ）に示す本実施形態における形状可変鏡は、図２に示す従来の通常構造の形状可変鏡と類似の構成を有するが、温度検知手段１０を、鏡部の鏡面と反対側における鏡固定部３の近傍又は鏡部の周辺部分に配置している。図８（ａ）においては、温度検知手段１０の幅が大きく描かれているが、実際には、図７に示すように温度検知手段１０の幅は、僅か０．１５ｍｍのように小さい。よって、鏡部の面積における温度検知手段１０の面積の占める割合は少ない。この温度検知手段１０を、鏡固定部３の近傍又は鏡部の周辺部分に配置することで、圧電素子２の伸縮により鏡部の鏡面形状を変化させても、温度検知手段１０は、ほとんど変形せず、温度を高い精度で測定でき、長期信頼性が確保された温度検知手段１０を提供することができる。
【００５８】
また、図８（ｂ）に示す本実施形態における形状可変鏡は、図３に示す従来の薄膜構造の形状可変鏡と類似の構成を有するが、温度検知手段１０を、鏡部の鏡面と反対側におけるスリット９と凸部１４との間に配置している。鏡部におけるスリット９の外側の部分は、圧電素子２の伸縮により鏡部の鏡面形状が変形しても、ほとんど変形しない。よって、このように温度検知手段を、鏡部の鏡面と反対側におけるスリット９と凸部１４との間に配置すれば、圧電素子２の伸縮により鏡部の鏡面形状が変形しても、温度検知手段１０は、ほとんど変形せず、温度を高い精度で測定でき、長期信頼性が確保された温度検知手段１０を提供することができる。
【００５９】
次に、本発明における第四の実施形態を説明する。
【００６０】
本実施形態における一つの形状可変鏡は、図２に示す従来の通常構造の形状可変鏡と類似の構成を有するが、温度検知手段１０を、鏡部の鏡面側における鏡固定部３に対応する場所に配置している。このように、温度検知手段１０を、鏡部の鏡面側における鏡固定部３に対応する場所に配置することによって、圧電素子２の伸縮により鏡部の鏡面形状を変化させても、温度検知手段１０は、全く変形せず、温度をさらに高い精度で測定でき、長期信頼性が確保された温度検知手段１０を提供することができる。
【００６１】
本実施形態における別の形状可変鏡は、図３に示す従来の薄膜構造の形状可変鏡と類似の構成を有するが、温度検知手段１０を、鏡部の鏡面側における凸部１４に対応する場所に配置している。このように、温度検知手段１０を、鏡部の鏡面側における凸部１４に対応する場所に配置することによって、圧電素子２の伸縮により鏡部の鏡面形状を変化させても、温度検知手段１０は、全く変形せず、温度をさらに高い精度で測定でき、長期信頼性が確保された温度検知手段１０を提供することができる。加えて、温度検知手段１０を、平坦な鏡部の鏡面側に形成しているので、温度検知手段１０を製造することが容易である。具体的には、温度検知手段１０を、フォトリソグラフ法における密着露光を使用して作製することができる。なお、本実施形態における形状可変鏡のように、温度検知手段１０を鏡部の鏡面側に形成する場合には、通常、温度検知手段１０を鏡基板６に作製した後、反射膜１を鏡基板６（及び温度検知手段１０）上に製膜する。
【００６２】
ここで、温度検知手段１０を、鏡部の鏡面と反対側における凸部１４の内側に作製するとすれば、薄膜構造の形状可変鏡は、鏡部の鏡面と反対側に凹部を有するので、例えば線幅４μｍのような細い金属薄膜抵抗体を、フォトリソグラフ法における密着露光によってパターニングすることは困難である。つまり、フォトリソグラフ法における密着露光によってパターニングするとすれば、フォトマスクと金属薄膜抵抗体を形成するためのマスク材との距離が約２００μｍほど離れるため、金属薄膜抵抗体のパターンがマスク材に不鮮明に露光されてしまう。金属薄膜抵抗体は、正確な抵抗値を有することが必要であり、金属薄膜抵抗体のパターンがマスク材に不鮮明に露光されてしまうと、金属薄膜抵抗体を正確に所望の形状に作製することができない。よって、正確な抵抗値を有する金属薄膜抵抗体得ることができず、正確な温度を検知することができる温度検知手段を提供することができない。これに対して、金属薄膜抵抗体を、鏡部の鏡面と反対側における凸部１４の内側において、所望の形状に作製するためには、ステッパー露光が有利であるが、フォトマスクを使用する密着露光よりも設備投資が大きく、コストが高くなる。
【００６３】
次に、本発明における第五の実施形態を図９と共に説明する。
【００６４】
図９（ａ）に示す本実施形態における形状可変鏡は、図２に示す従来の通常構造の形状可変鏡と類似の構成を有するが、温度検知手段１０を、鏡部の鏡面と反対側における鏡固定部３の内部に配置している。また、図９（ｂ）に示す本実施形態における形状可変鏡は、図３に示す従来の薄膜構造の形状可変鏡と類似の構成を有するが、温度検知手段１０を、鏡部の鏡面と反対側の凸部１４に配置している。
【００６５】
図９（ａ）、（ｂ）に示すように、この温度検知手段１０を、鏡固定部３の内部又は凸部１４に配置することで、圧電素子２の伸縮により鏡部の鏡面形状を変化させても、温度検知手段１０は、全く変形せず、温度を高い精度で測定でき、長期信頼性が確保された温度検知手段１０を提供することができる。また温度検知手段１０は、鏡部と鏡固定用部材との間に挟まれるため、鏡部に温度検知手段１０を形成することに起因する、温度検知手段１０の膜応力による形状可変鏡の初期鏡面形状の歪みを除去することができる。ここで、鏡部と鏡固定用部材との間に挟まれる温度検知手段１０と、温度検知手段１０の金属薄膜抵抗体１２の抵抗値を測定する手段とを接続するために、金属薄膜抵抗体１２のボンディングパッド１０’を、鏡固定部３又は凸部１４以外の部分まで延長して形成する。また、図９（ｂ）に示す薄膜構造の形状可変鏡においては、凸部１４に温度検知手段１０を形成するため、安価なフォトリソグラフ法の密着露光を使用することができる。
【００６６】
次に、本発明における第六の実施形態を説明する。
【００６７】
本実施形態における形状可変鏡は、図２又は図３に示す従来の形状可変鏡と類似の構成を有するが、温度検知手段１０を、鏡部の鏡面側における鏡固定部３に対応する場所又は凸部１４に対応する場所に配置している。このように、温度検知手段１０を、鏡部の鏡面側における鏡固定部３に対応する場所又は凸部１４に対応する場所に配置することで、圧電素子２の伸縮により鏡部の鏡面形状を変化させても、温度検知手段１０は、全く変形せず、温度を高い精度で測定でき、長期信頼性が確保された温度検知手段１０を提供することができる。また温度検知手段１０は、鏡部における鏡面形状の変形しない部分に配置されるため、温度検知手段１０の膜応力による形状可変鏡の初期鏡面形状の歪みを除去することができる。また、温度検知手段１０を鏡部の鏡面側に配置することにより、ボンディングパッド温度検知手段形成領域の外側まで形成する必要がなく、鏡部を鏡固定用部材に取り付けた後でも、温度検知手段１０を、温度検知手段１０の金属薄膜抵抗体１２の抵抗値を測定する手段に接続することができる。
【００６８】
次に、本発明における第七の実施形態を説明する。
【００６９】
本実施形態の形状可変鏡は、第四の実施形態、及び第六の実施形態において、鏡基板６上で、反射膜１と温度検知手段１０が形成される領域（温度検知手段形成領域）を分離している。反射膜１は、金（Ａｕ）等の反射率の高い金属薄膜や誘電体多層膜で形成され、通常は、鏡面の全体に成膜される。しかしながら、鏡部の鏡面側に温度検知手段１０を形成した構造を有する形状可変鏡においては、温度検知手段１０の上にも反射膜１を形成すると、反射膜１の膜応力によって、温度検知手段１０の金属薄膜抵抗体１２に応力が発生して、抵抗値が変化する場合もある。特に反射膜１を誘電体多層膜で形成する場合には、所望に反射率を有する反射膜１を実現するために、反射膜１は、厚さ約３μｍの約３０層程度の積層膜である場合もある。また、温度検知手段１０を温度検知手段１０の金属薄膜抵抗体１２の抵抗値を測定する手段に接続するため、温度検知手段１０の上には何も存在しないことが望ましい。鏡基板６上で、反射膜１と温度検知手段１０が形成される領域を分離することで、反射膜１の膜応力によって、温度検知手段１０の金属薄膜抵抗体１２に抵抗値が変化することを防止し、正確に温度を測定することができる温度検知手段を有する形状可変鏡を提供することができる。
【００７０】
本実施形態における、鏡基板６上で反射膜１が温度検知手段形成領域と分離している形状可変鏡は、まず、鏡基板６上の温度検知手段形成領域に予め温度検知手段を作製する。その後、スパッタ法により反射膜１を鏡基板上に成膜するときに、メタルマスクを用いた蒸着を用いて、新たな工程を追加することなく、温度検知手段形成領域から分離して反射膜１を成膜することができる。なお、検知手段形成領域の面積は、図７に示すように、鏡部の面積と比較して非常に小さくすることができるため、温度検知手段形成領域用の新たなスペースを鏡基板６上に確保する必要はない。
【００７１】
次に、本発明における第八の実施形態を図１０と共に説明する。
【００７２】
本実施形態の形状可変鏡は、図３（ｂ）に示す第三の実施形態における薄膜構造の形状可変鏡において、凸部１４に形成された、温度検知手段１０の金属薄膜抵抗体１２に接続する配線の幅を、金属薄膜抵抗体１２のボンディングパッドの長さ又は幅よりも広くしている。図３（ｂ）に示す薄膜構造の形状可変鏡において、鏡部の鏡面と反対側の面に温度検知手段１０に対する配線を形成する場合、図１０（ａ）に示すように、鏡基板６の凸部１４に配線１０’を形成し、これらの配線１０’を、凸部１４における鏡固定用部材８と接触する面で、導電性接着剤やバンプ等を用いて、鏡固定用部材８に形成された配線と電気的に接続する。
【００７３】
しかしながら、図１０（ａ）における線ｂ−ｂ’に沿った断面を表す図１０（ｂ）に示すように、凸部１４の側面と鏡固定用部材８に接触する面との境界部分で、配線１０’の膜厚が薄くなり、この境界部分で、抵抗値が増加する。温度検知手段１０の金属薄膜抵抗体１２を使用して周囲の温度を検知する場合、理想的には、配線などの不正抵抗を排除することによって、ダイナッミックレンジの大きな温度検知手段を実現することができる。よって、上述の境界差部で発生する抵抗値の増加は、望ましくない。本実施形態における形状可変鏡では、図１０（ｃ）に示すように、凸部１４に形成された、温度検知手段１０の金属薄膜抵抗体１２に接続する配線１０’の幅を、金属薄膜抵抗体１２のボンディングパッドの長さ又は幅よりも広くする。これにより、凸部１４の側面と鏡固定用部材８に接触する面との境界部分で、配線１０’の膜厚が薄くなっても、配線１０’の幅が広くなっているため、その境界部分における抵抗値の増加を防止することができる。例えば、配線１０’の境界部分における膜厚が、他の部分における膜厚の半分になるとしても、配線の幅を通常の幅の二倍にすることで、境界部分における抵抗値の増大を無くすことができる。この配線１０’の幅は、広いことが望ましいが、形状可変鏡における全体の設計のバランスを考慮して配線１０’の幅を決定するべきである。また、配線１０’の幅が広いので、配線１０’を凸部１４に容易に形成することができる。
【００７４】
次に、本発明における第九の実施形態を図１０と共に説明する。
【００７５】
本実施形態の形状可変鏡は、前述の全ての実施形態において、金属薄膜抵抗体としてＰｔ薄膜を用いる場合に、Ｐｔ薄膜の抵抗値を１ｋΩ乃至１０ｋΩとしたものである。
【００７６】
室温（２５℃）を周囲の温度に関する基準とすると、室温において温度検知手段で測定される抵抗値Ｒ２５は、次の式１
Ｒ２５＝Ｒｓ＋Ｒ１　　…（式１）
で表される。ここでＲｓは、室温における金属薄膜抵抗体の抵抗値、Ｒ１は、配線などに起因する不正抵抗の値である。
【００７７】
また、周囲の温度が１℃変化したとき（２６℃）の温度検知手段で測定される抵抗値Ｒ２６は、式２
Ｒ２６＝Ｒｓ＋Ｒ１＋（Ｒｓ×ＴＣＲ×１（℃））　　…（式２）
で表される。ここで、ＴＣＲは、抵抗温度係数である。
【００７８】
式１及び式２より、抵抗値は、温度に対してほぼ線形に変化する。ここで、不正抵抗の値Ｒ１が、金属薄膜抵抗体の抵抗値Ｒｓに比べて無視できるほど小さいことが望ましい。不正抵抗の値が増加すると、温度変化に対する温度検知手段で測定される抵抗値の変化が、小さくなり、温度を検知する感度が低下する。よって、金属薄膜抵抗体の抵抗値Ｒｓは、通常、不正抵抗の値Ｒ１に対して相対的に大きく設計され、温度に対する温度検知手段で測定される抵抗値の変化を大きくする。しかしながら、金属薄膜抵抗体の抵抗値Ｒｓを大きくしすぎると、金属薄膜抵抗体に定電流を流すために必要な電圧を高くしなければならない。よって、金属薄膜抵抗体の抵抗値Ｒｓは、適当な値に設定する必要がある。
【００７９】
ここで、不正抵抗が金属薄膜抵抗体の抵抗値に比べて無視できる程小さいとし、ＴＣＲが、３２００ｐｐｍ／℃とし、室温における金属薄膜抵抗体の抵抗値を１ｋΩとして金属薄膜抵抗体を設計する。室温でこの金属薄膜抵抗体に１ｍＡの定電流を流すとすれば、必要な電圧は、約１Ｖである。温度が１℃変化したときの温度検知手段で測定される抵抗値の変化は、式１及び式２から３．２Ωであり、電圧の変化は、３．２ｍＶとなる。同様に、不正抵抗が金属薄膜抵抗体の抵抗値に比べて無視できる程小さいとし、ＴＣＲが、３２００ｐｐｍ／℃とし、室温における金属薄膜抵抗体の抵抗値を１０ｋΩとして金属薄膜抵抗体を設計する。この場合に、室温でこの金属薄膜抵抗体に０．３ｍＡの定電流を流すとすれば、必要な電圧は、約３Ｖである。温度が１℃変化したときの温度検知手段で測定される抵抗値の変化は、３２Ωであり、電圧の変化は、９．６ｍＶとなる。
【００８０】
上記の設計条件は、光ピックアップ装置の電源の電圧を５Ｖと仮定し、金属薄膜抵抗体に印加する電圧が、この電源の電圧よりも小さくなるようにして決定した。室温における金属薄膜抵抗体の抵抗値を１ｋΩ〜１０ｋΩとすれば、金属薄膜抵抗体に上記のような定電流を流すために必要な電力は、１ｍＶＡ〜９ｍＶＡとなる。よって、温度検知手段が形成された形状可変鏡を光ピックアップ装置において使用する場合、温度検知手段における金属薄膜抵抗体の室温における抵抗値を１ｋΩ〜１０ｋΩの範囲内で設計すると、温度変化を検知する感度と消費電力のバランスがとれた温度検知手段を形状可変鏡に提供することができる。
【００８１】
【発明の効果】
本発明によれば、周囲の温度を実質的に正確に測定することができる温度検知手段を有し、初期平面形状の歪みが少ない、形状可変鏡及び該形状可変鏡を有する光ピックアップ装置を備えた光ディスク情報入出力装置を提供することができる。
【００８２】
【図面の簡単な説明】
【図１】光ディスクのチルトによるコマ収差の発生を説明する図であり、（ａ）は、ＣＤにおける図、（ｂ）は、ＤＶＤにおける図である。
【図２】従来の通常構造の形状可変鏡の断面図である。
【図３】従来の薄膜構造を有する形状可変鏡を示す図であり、（ａ）は、鏡固定用部材を取り除いて反射膜と反対側から見た平面図であり、（ｂ）は、（ａ）のＡ−Ａ’方向における断面図であり、（ｃ）は、鏡面形状の変化を説明する図である。
【図４】チルトによって生じたレーザ光の波面収差の等高線図である。
【図５】形状可変鏡のＡ−Ａ’方向におけるレーザ光の波面収差の低減を説明する図であり、（ａ）は、チルトにより発生したレーザ光の波面収差図、（ｂ）は、形状可変鏡により発生させた波面収差図、（ｃ）は、形状可変鏡で波面収差を低減した後の波面収差図である。
【図６】本発明の第一及び第二の実施形態における形状可変鏡を説明する図であり、（ａ）は、通常構造の形状可変鏡に温度検知手段を設けた形状可変鏡の図、（ｂ）は、薄膜構造を有する形状可変鏡に温度検知手段を設けた形状可変鏡の図である。
【図７】本発明における形状可変鏡の温度検知手段を説明する図である。
【図８】本発明の第三の実施形態における形状可変鏡を説明する図であり、（ａ）は、通常構造の形状可変鏡に温度検知手段を設けた形状可変鏡の図、（ｂ）は、薄膜構造を有する形状可変鏡に温度検知手段を設けた形状可変鏡の図である。
【図９】本発明の第五の実施形態における形状可変鏡を説明する図であり、（ａ）は、通常構造の形状可変鏡に温度検知手段を設けた形状可変鏡の図、（ｂ）は、薄膜構造を有する形状可変鏡に温度検知手段を設けた形状可変鏡の図である。
【図１０】本発明の第八の実施形態における形状可変鏡を説明する図であり、（ａ）は、幅の狭い温度検知手段用の配線を形成した形状可変鏡の図、（ｂ）は、（ａ）及び（ｃ）における線ｂ−ｂ’方向に沿った断面図、（ｃ）は、幅の広い温度検知手段用の配線を形成した形状可変鏡の図である。
【符号の説明】
１　　鏡材、反射膜
２　　圧電素子
３　　鏡固定部
４ａ、５ａ　　電極
４ｂ、４ｃ、５ｂ、５ｃ　　配線
６　　鏡基板
７　　絶縁膜
８　　鏡固定用部材
９　　スリット
１０　　温度検知手段
１０’　　配線、ボンディングパッド
１１　　密着層
１２　　金属薄膜抵抗体
１３　　保護膜
１４　　凸部
１０１ａ、１０１ｂ　　対物レンズ
１０２ａ、１０２ｂ　　樹脂層
１０３ａ、１０３ｂ　　スポット
１０８　　記録層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a deformable mirror that changes the shape of a mirror surface of a mirror unit, and an optical disk information input / output device including an optical pickup device.
[0002]
[Prior art]
Generally, there are a CD and a DVD as an optical disk information input / output device using an optical disk. Since DVDs and the like have a higher recording density than CDs, the conditions for reading and writing information are becoming more stringent. For example, it is ideal that the optical axis of the optical pickup device is perpendicular to the disk surface. However, since the optical disk is actually made of resin, the disk surface has a considerable undulation. The optical axis is not always perpendicular to the disk surface, and the disk surface may have an inclination with respect to the optical axis (hereinafter, the inclination of the disk surface with respect to the optical axis is referred to as tilt). As shown in FIG. 1, both the CD and DVD optical disks have the recording layer 108 interposed between the resin layers 102a and 102b. Therefore, when the tilt, that is, the disk surface is tilted, the optical path of the laser beam is bent and coma aberration is reduced. As a result, the spot cannot be correctly focused on the optical disk as shown by 103a and 103b in FIG. If the coma aberration is larger than the allowable amount, a problem occurs that information cannot be read and written correctly.
[0003]
As a means for reducing the aberration caused by the tilt, there is a method of reducing the thickness of a resin layer between the objective lens and the recording layer. Actually, in a DVD as shown in FIG. 1B, the thickness of the resin layer 102b between the objective lens 101b and the recording layer 108 is reduced by half compared with the case of the CD shown in FIG. Some are intended to reduce coma. However, in this method, if the recording density is to be made higher than that of the DVD, the thickness of the resin layer is further reduced to reduce the influence of tilt, but this time, dust and scratches are formed on the optical disk. In such a case, a problem occurs that the signal cannot be read and written correctly. For this reason, the present situation is that the optical axis of the optical pickup device is tilted by the actuator to cope with tilt.
[0004]
As means for optically correcting the influence of tilt, there is a method using a liquid crystal plate described in JP-A-10-79135. As means for correcting coma caused by tilt using a piezoelectric element, a method using a transparent piezoelectric element in the optical path of laser light described in Japanese Patent Application Laid-Open No. 5-144056, or a plurality of actuators described in Japanese Patent Application Laid-Open No. 5-333274 are used. A method using a deformable mirror used has been proposed.
[0005]
However, in the method of correcting the coma aberration by controlling the phase using a liquid crystal plate as disclosed in Japanese Patent Application Laid-Open No. H10-79135, the amount of light attenuates because the laser passes through the liquid crystal plate, and the energy required for writing is obtained. It is difficult to use it for high-frequency operation required for controlling tangential tilt, in particular, due to the characteristics of liquid crystal.
[0006]
Further, in order to obtain a required change in thickness with a single transparent piezoelectric element as disclosed in Japanese Patent Application Laid-Open No. 5-144056, a high voltage is actually required, which is not practical for use in an optical pickup device or the like.
Further, in the method of controlling the phase by deforming the mirror itself of the deformable mirror with a laminated piezoelectric element as disclosed in Japanese Patent Application Laid-Open No. 5-333274, wiring and the like are not considered for use in small components such as an optical pickup device. , And the assembly cost becomes high. Further, even if the problems such as wiring can be solved, it is difficult to reduce the size of the multilayer piezoelectric element both technically and costly.
[0007]
As a method of solving the above-mentioned problem of the conventional technology, a method of reducing a wavefront aberration (mainly coma aberration) generated by a tilt or the like with a deformable mirror using a unimorph-type or bimorph-type piezoelectric element can be considered. This is, for example, a deformable mirror having a variable mirror surface shape as shown in FIG. 2 (hereinafter referred to as a deformable mirror having a normal structure). FIG. 2 is a sectional view of the deformable mirror. In this deformable mirror, when the mirror material 1 is expressed on one surface of the mirror substrate 6 and the mirror surface side of the mirror material 1 is expressed as a lower surface, the wiring 4b is formed on the mirror substrate 6, the electrode 4a is formed thereon, and the piezoelectric material is formed thereon. The piezoelectric element 2 has a unidirectional polarity, and further has two electrodes 5a thereon. The mirror substrate 6 is fixed at the mirror fixing part 3 by a concave mirror fixing member 8, and the mirror fixing member 8 is connected to the wiring 4b via a wire 4c and the electrode 5a via the wire. Wiring 5c is provided. Here, when a potential difference is given between the electrode 4a and the electrode 5a via the wiring 4c and the two wirings 5c, the piezoelectric element 2 expands and contracts according to the potential difference, and the mirror section including the mirror substrate 6 and the mirror material 1 is provided. The shape of the mirror surface. By changing the piezoelectric polarity of the two electrodes 5a or changing the voltage applied to the two electrodes 5a, the expansion and contraction of the piezoelectric element 2 can be adjusted to control the mirror shape of the mirror.
[0008]
3 (a) and 3 (b) are diagrams showing another form of a deformable mirror (hereinafter, referred to as a thin film structure). FIG. 3 (a) is a mirror fixing having wirings 4c and 5c. FIG. 3 is a plan view of the deformable mirror seen from the side opposite to the reflection film 1 with the member 8 removed, (b) is a cross-sectional view of the deformable mirror in the AA ′ direction of (a), and (c). () Is a diagram for explaining a change in the mirror surface shape of the deformable mirror. As shown in FIGS. 3A and 3B, in the deformable mirror having the thin film structure, a mirror surface is referred to as a lower side, and a side opposite to the mirror surface is referred to as an upper side. 1, an insulating film 7 is provided on the mirror substrate 6, and wirings 4b and 5b are provided thereon. The mirror substrate 6 has a thick convex portion 14 in a peripheral portion. There are two electrodes 4a connected to the wiring 4b on the wiring 4b, a piezoelectric element 2 is bonded on the electrode 4a, and two electrodes 4a facing the two electrodes 4a on the piezoelectric element 2. There is an electrode 5a. Between the wiring 4b formed around the mirror substrate 6 and the wiring 4b below the piezoelectric element 2 connected to the electrode 4a, and between the wiring 5b formed around the mirror substrate 6 and the piezoelectric element 2. There are connecting wires between the formed electrodes 5a. Here, a portion including the reflection film, the mirror substrate, the insulating film, and the wiring is defined as a mirror portion. Further, in the deformable mirror shown in FIG. 3, a slit is provided in the mirror to facilitate deformation of the mirror. Here, a portion including the piezoelectric element and the electrode is defined as a piezoelectric substrate portion. The mirror portion having the piezoelectric substrate portion and the wire is fixed to the mirror fixing portion 3 of the mirror fixing member 8 having the wirings 4c and 5c by a thick convex portion 14 around the mirror portion. In the deformable mirror having the thin film structure shown in FIG. 3, the portion of the mirror substrate 6 opposite to the mirror surface is etched to reduce the thickness of the mirror substrate 6, and the mirror surface shape of the mirror portion is changed at a low voltage. be able to.
[0009]
In such a deformable mirror having a thin film structure, it is assumed that the wiring 4b, that is, the two electrodes 4a are grounded, and a positive voltage is applied to one of the two electrodes 5a and a negative voltage is applied to the other from the wiring 5b. The mirror substrate 6 itself does not expand and contract when a voltage is applied, but the piezoelectric element 2 expands and contracts when a voltage is applied. If a positive voltage is applied to the electrode 5a and the piezoelectric element 2 at the portion where the electrode 5a is installed contracts, if a negative voltage is applied, the piezoelectric element 2 at that portion expands and the electrode 5a expands. The mirror surface of the portion where a positive voltage is applied to 5a is convex, and the mirror surface of the portion where a negative voltage is applied to the electrode 5a is concave. As a result, as shown in FIG. 3C, the mirror surface shape of the deformable mirror shown in FIG. 3 has a convex surface and a concave surface across the center of the mirror surface in the AA ′ direction, and in the AA ′ direction. The cross section has a wavy shape in which the center of the mirror surface corresponds to a node. The horizontal axis in FIG. 3C is the axis in the AA ′ direction of the deformable mirror shown in FIG. 3, and the vertical axis is the amount of change in the mirror surface shape in the cross section in the AA ′ direction. When a voltage opposite to that described above is applied to the two electrodes 5a, the shape becomes a wave shape opposite to the shape shown in FIG. By changing the piezoelectric polarity of the two electrodes 5a or changing the voltage applied to the two electrodes 5a, the expansion and contraction of the piezoelectric element 2 can be adjusted to control the mirror shape of the mirror.
[0010]
By installing such a deformable mirror on the optical axis of an optical pickup device in an optical disk information input / output device and controlling the shape of the mirror surface, it becomes possible to reduce coma due to tilt. In the optical disk information input / output device, when the optical disk is tilted, that is, tilted with respect to the direction perpendicular to the optical axis of the laser light, the wavefront of the laser light reflected back from the optical disk is disturbed. Aberration occurs. The wavefront aberration of the laser light returning from the tilted optical disk and entering the mirror surface of the deformable mirror is represented by a contour line as shown in FIG. 4 with respect to the cross section of the light beam of the laser light. Here, in the cross section of the laser beam, the direction corresponding to the direction in which the optical disk is tilted is the AA ′ direction in FIG. That is, wavefront aberration (coma aberration) whose sign changes along the AA 'direction occurs.
[0011]
In order to reduce the wavefront aberration generated by such a tilt, the shape-variable mirror as shown in FIG. 3 is made to match the AA ′ direction in FIG. 3A with the AA ′ direction in FIG. And placed on the optical axis of the optical pickup device. By properly controlling the shape of the mirror surface such that a convex surface and a concave surface are generated in the AA 'direction by the operation of the deformable mirror described above, it is possible to correct or reduce wavefront aberration (coma aberration) due to tilt. . Here, for the sake of simplicity, attention is paid only to the AA 'direction in FIG. 4, and the reduction of the wavefront aberration of the laser light will be described with reference to FIGS. FIG. 5A is a wavefront aberration diagram in the AA ′ direction of FIG. 4 regarding the wavefront aberration of the laser light generated when the optical disc is tilted. Here, the vertical axis in FIGS. 5A to 5C is the wavefront aberration, and the horizontal axis in FIG. 3 is the axis in the AA ′ direction of FIG. 4 (that is, the axis in the AA ′ direction of the deformable mirror). Axis). If the optical disk does not tilt and is perpendicular to the optical axis of the laser beam, no wavefront aberration occurs as shown in FIG. 5A, and the wavefront coincides with the horizontal axis. FIG. 5B is a diagram illustrating the wavefront aberration of the reflected light when the deformable mirror is intentionally operated to generate aberration, and the deformable mirror is irradiated with the aberration-free light. Now, assuming that the optical disc is tilted and the wavefront aberration of the reflected light from the optical disc is as shown in FIG. 5A, the wavefront aberration of the light reflected by the deformable mirror when the optical disc is not tilted is shown in FIG. The shape of the mirror surface of the deformable mirror is controlled so as to satisfy b). In this case, the wavefront aberrations of FIGS. 5A and 5B cancel each other, and the wavefront aberration of the reflected light from the deformable mirror becomes as shown in FIG. Wavefront aberration can be reduced as compared with FIG.
[0012]
[Problems to be solved by the invention]
Here, in the deformable mirror as described above, the mirror surface shape of the mirror portion in a state where no voltage is applied to the piezoelectric element (hereinafter, referred to as an initial planar shape for simplicity) changes the ambient temperature. It is known to fluctuate with changes. In particular, in the deformable mirror having the thin film structure shown in FIG. 3, since the thickness of the mirror substrate 6 is small, a change in the mirror surface shape due to a temperature change is remarkable. That is, the portion of the mirror portion of the deformable mirror whose mirror surface shape changes includes the reflection film 1, the mirror substrate 6, the insulating film 7, the wiring 4b, and the like, and is attached with the electrodes 4a, 5a, the wiring 4b, and the adhesive. The piezoelectric element 2 is provided, and these components have different coefficients of thermal expansion. Therefore, these components expand and contract separately due to a change in ambient temperature, so that the initial mirror surface shape of the mirror section is distorted as a whole.
[0013]
Therefore, it is necessary to compensate for the temperature change of the initial planar shape of the deformable mirror in order to keep the initial planar shape of the deformable mirror flat even when the surrounding temperature changes. As a method of compensating for the temperature change of the initial planar shape of the deformable mirror, the ambient temperature is measured at any time by a temperature detecting means, and an offset voltage is applied to the piezoelectric element based on the measured temperature. There is a method of correcting the distortion of the planar shape.
[0014]
As the temperature detecting means, a commercially available temperature detecting means can be used. Such a temperature detecting means may be mounted near a portion of the deformable mirror where the mirror surface shape changes, where temperature compensation is required. However, the attachment of the temperature detecting means to a small deformable mirror installed in an optical pickup device or the like of an optical disk information input / output device has a problem that a place for attaching the temperature detecting means must be secured. For this reason, it is desirable that the temperature detecting means composed of a thin film is formed integrally with the mirror portion of the deformable mirror. The temperature detecting means composed of such a thin film includes a metal thin-film resistor whose resistance value varies with a change in temperature and an insulating film covering the metal thin-film resistor.
[0015]
However, the mirror substrate in the mirror portion of the deformable mirror, particularly the deformable mirror having a thin film structure, is formed very thin (for example, 50 μm to 200 μm) in order to efficiently deform the mirror surface shape of the mirror portion. Therefore, if the temperature detecting means composed of a thin film is simply formed integrally with the mirror part, the initial mirror surface shape of the mirror part is distorted due to the influence of the film stress of the metal thin film resistor and the insulating film in the temperature detecting means. In some cases, a change in the initial planar shape of the mirror due to a change in ambient temperature is further emphasized. Further, in the temperature detecting means composed of a thin film, when the material of the metal thin film resistor is platinum (Pt), the metal thin film resistor of Pt is made of general silicon oxide (SiO 2). 2 3) Poor adhesion to the insulating film. Therefore, SiO 2 The thermal conductivity of Pt to the metal thin film resistor through the insulating film of Pt is insufficient, and the temperature measurement due to the change in the resistance of the metal thin film resistor of Pt becomes inaccurate, and the reliability as the temperature detecting means is secured. It becomes difficult. Further, when a metal thin-film resistor in the temperature detecting means is arranged near a portion of the mirror portion of the deformable mirror where the mirror surface shape changes, when the voltage is applied to the piezoelectric element to change the mirror surface shape of the mirror portion, the mirror surface is changed. A stress is generated in the metal thin-film resistor due to the change in shape, the resistance value fluctuates, and the ambient temperature cannot be measured accurately.
[0016]
The present invention has been made in view of the above-mentioned problems, and has a temperature detecting means capable of measuring an ambient temperature substantially accurately, a deformable mirror having little distortion of an initial planar shape, and a deformable mirror. It is an object to provide an optical disk information input / output device including an optical pickup device having a mirror.
[0017]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a deformable mirror in which the shape of the mirror surface of the mirror portion is variable, the device further comprising temperature detecting means for detecting a temperature around the deformable mirror, and the temperature detecting means is provided in the mirror portion. The mirror surface is provided at a portion where the shape of the mirror surface does not change.
[0018]
According to the first aspect of the present invention, there is provided a temperature detecting means for detecting a temperature around the deformable mirror, and the temperature detecting means is provided at a portion of the mirror portion where the shape of the mirror surface does not change. In addition, it is possible to provide a deformable mirror having temperature detecting means capable of substantially accurately measuring the ambient temperature, and having a small initial planar shape distortion.
[0019]
According to a second aspect of the present invention, there is provided a deformable mirror in which the shape of the mirror surface of the mirror portion is variable, the device further comprising: temperature detecting means for detecting a temperature around the deformable mirror; The mirror surface is provided integrally with a portion where the shape of the mirror surface does not change.
[0020]
According to the second aspect of the present invention, there is provided temperature detecting means for detecting the temperature around the deformable mirror, and the temperature detecting means is provided integrally with a portion of the mirror portion where the shape of the mirror surface does not change. Therefore, it is possible to provide a deformable mirror having temperature detecting means capable of measuring the ambient temperature substantially accurately, and to reduce distortion of the initial planar shape, and to reliably form the temperature detecting means. It can be provided on a deformable mirror.
[0021]
According to a third aspect of the present invention, in the deformable mirror according to the first or second aspect, the shape of the mirror surface of the mirror portion is changed by expansion and contraction of a piezoelectric element provided on the opposite side of the mirror portion to the mirror surface. The temperature detecting means may be arranged between a portion where a member supporting the mirror portion is in contact with the mirror portion and a portion where the piezoelectric element is provided, on a side opposite to the mirror surface of the mirror portion. Features.
[0022]
According to the third aspect of the present invention, the shape of the mirror surface of the mirror portion is changed by expansion and contraction of a piezoelectric element provided on a side of the mirror portion opposite to the mirror surface, and the temperature detecting means is provided in the mirror portion. On the opposite side of the mirror surface, the member supporting the mirror portion is disposed between the portion in contact with the mirror portion and the portion where the piezoelectric element is provided. Even if the shape is changed, it is possible to provide a deformable mirror having a temperature detecting means capable of measuring the temperature with high accuracy and ensuring long-term reliability.
[0023]
According to a fourth aspect of the present invention, in the deformable mirror according to the first or second aspect, the shape of the mirror surface of the mirror portion is changed by expansion and contraction of a piezoelectric element provided on a side of the mirror portion opposite to the mirror surface. The temperature detecting means includes a portion on the mirror surface side of the mirror portion, on a side opposite to the mirror surface of the mirror portion, in which a member supporting the mirror portion contacts the mirror portion, and a portion opposite to the mirror surface of the mirror portion. The piezoelectric element is disposed between the portions where the piezoelectric element is provided on the side.
[0024]
According to the invention described in claim 4, the shape of the mirror surface of the mirror portion is changed by expansion and contraction of a piezoelectric element provided on the opposite side of the mirror portion to the mirror surface, and the temperature detecting means is provided in the mirror portion. A portion of the mirror surface side, a portion where the member supporting the mirror portion is in contact with the mirror portion on the side opposite to the mirror surface of the mirror portion, and a portion where the piezoelectric element is provided on the side opposite to the mirror surface of the mirror portion The variable-shape mirror has temperature detecting means that can measure the temperature with high accuracy even if the shape of the mirror surface is changed due to expansion and contraction of the piezoelectric element, and ensures long-term reliability. And the temperature detecting means can be easily manufactured.
[0025]
According to a fifth aspect of the present invention, in the shape-variable mirror according to the first or second aspect, the temperature detecting means is configured such that a member supporting the mirror portion on the opposite side of the mirror surface of the mirror portion contacts the mirror portion. In a portion where the light is emitted.
[0026]
According to the invention as set forth in claim 5, the temperature detecting means is disposed on a portion of the mirror portion opposite to the mirror surface, where the member supporting the mirror portion is in contact with the mirror portion.
A deformable mirror having temperature detecting means capable of measuring temperature with high accuracy and ensuring long-term reliability can be provided, and distortion of the initial mirror surface shape of the deformable mirror due to film stress of the temperature detecting means can be removed. be able to.
[0027]
According to a sixth aspect of the present invention, in the deformable mirror according to the first or second aspect, the temperature detecting means supports the mirror portion on the side of the mirror surface of the mirror portion opposite to the mirror surface of the mirror portion. And a member that contacts the mirror portion.
[0028]
According to the invention as set forth in claim 6, the temperature detecting means is a portion on the mirror surface side of the mirror portion, on a side opposite to the mirror surface of the mirror portion, where a member supporting the mirror portion contacts the mirror portion. In addition, it is possible to provide a deformable mirror having temperature detecting means that is easy to manufacture, can measure temperature with high accuracy, and ensures long-term reliability, and has a film stress of the temperature detecting means. The distortion of the initial mirror surface shape of the deformable mirror due to the above can be removed.
[0029]
According to a seventh aspect of the present invention, in the deformable mirror according to the fourth or sixth aspect, the mirror unit includes a reflection film on the mirror surface side of the mirror unit, the light reflecting a light incident on the deformable mirror, The temperature detecting means is arranged at a portion of the mirror portion where the reflection film is not provided.
[0030]
According to the invention as set forth in claim 7, the mirror section includes a reflection film for reflecting light incident on the shape-variable mirror on the mirror surface side of the mirror section, and the temperature detecting means includes a light-reflecting member provided on the mirror section. Since it is arranged in a portion where the reflection film is not provided, it is possible to prevent a decrease in measurement accuracy of the temperature detection device due to a film stress of the reflection film, and to provide a deformable mirror having a temperature detection device capable of accurately measuring the temperature. Can be provided.
[0031]
According to an eighth aspect of the present invention, in the deformable mirror according to the third or fifth aspect, a portion of the mirror portion opposite to the mirror surface where a member supporting the mirror portion contacts the mirror portion is the mirror. A member for supporting the mirror portion on a side opposite to the mirror surface of the portion is a convex portion for a portion not in contact with the mirror portion; and the temperature detecting means has an electrode for applying a voltage for driving the temperature detecting means. A wiring connected to the electrode of the temperature detecting means is provided at least on the projection, and a width of the wiring at the projection is wider than a width of the electrode.
[0032]
According to the invention as set forth in claim 8, the portion of the mirror portion opposite to the mirror surface, the portion where the member supporting the mirror portion contacts the mirror portion, the portion of the mirror portion opposite to the mirror surface, The member supporting the mirror unit is a protrusion for a portion that does not contact the mirror unit, and the temperature detection unit has an electrode for applying a voltage for driving the temperature detection unit, and the electrode of the temperature detection unit is The wiring to be connected is provided at least on the convex portion, and the width of the wiring at the convex portion is wider than the width of the electrode, so that the wiring can be easily formed on the convex portion and the temperature detecting means can be formed. It is possible to provide a deformable mirror having a temperature detecting means which suppresses an increase in resistance value at a convex portion of a wiring connected to the device and has a small irregular resistance and a high sensitivity of temperature measurement.
[0033]
According to a ninth aspect of the present invention, in the deformable mirror according to any one of the first to eighth aspects, the temperature detecting means includes a platinum thin film resistor and a pentoxide pentoxide covering at least a part of the resistor. It is characterized by including an insulating layer made of tantalum or silicon nitride.
[0034]
According to the ninth aspect of the present invention, the temperature detecting means includes a thin-film resistor made of platinum and an insulating layer made of tantalum pentoxide or silicon nitride covering at least a part of the resistor. It is possible to provide a deformable mirror having good adhesion between the body and the insulating layer and having a temperature detecting means capable of accurately and accurately measuring the temperature.
[0035]
According to a tenth aspect of the present invention, in the deformable mirror according to the ninth aspect, the resistance value of the resistor is 1 kΩ to 10 kΩ.
[0036]
According to the tenth aspect of the present invention, since the resistance value of the resistor is 1 kΩ to 10 kΩ, a deformable mirror provided with temperature detecting means having appropriate sensitivity for temperature measurement and appropriate power consumption is provided. be able to.
[0037]
According to an eleventh aspect of the present invention, there is provided an optical disk information input / output device including an optical pickup device, comprising the deformable mirror according to any one of the first to tenth aspects.
[0038]
According to an eleventh aspect of the present invention, since the apparatus has the deformable mirror according to any one of the first to tenth aspects, it has temperature detecting means capable of measuring the ambient temperature substantially accurately. It is possible to provide an optical disk information input / output device including an optical pickup device having a deformable mirror with little distortion of a planar shape.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0040]
First, a first embodiment of the present invention will be described with reference to FIG. FIG. 6 shows a deformable mirror according to the first embodiment of the present invention, and FIG. 6 (a) is a plan view of the deformable mirror of the present invention as viewed from the side opposite to the mirror surface. However, for the sake of simplicity, the mirror fixing member and some of the wires and wires are omitted. FIGS. 6B and 6C are cross-sectional views of the temperature detecting means provided in the deformable mirror of the present invention.
[0041]
The basic configuration of the deformable mirror of the present embodiment is the same as the deformable mirror having the normal structure shown in FIG. As shown in FIG. 6A, in the deformable mirror of this embodiment, the mirror side is referred to as the lower side, and the side opposite to the mirror surface is referred to as the upper side. There is a mirror material, and a wiring 4 b is provided on the mirror substrate 6. On the wiring 4b, there is an electrode connected to the wiring 4b, on which the piezoelectric element 2 is bonded, and on the piezoelectric element 2, two electrodes 5a opposed to the above-mentioned two electrodes are provided. There is.
[0042]
Unlike the conventional deformable mirror shown in FIG. 2, in the deformable mirror according to the present embodiment, a temperature detecting means 10 is formed on a part of the mirror substrate 6. Specifically, the temperature detecting means 10 is formed in the mirror substrate 6 near the mirror fixing portion 3 (portion fixed by the mirror fixing member). Here, when the mirror surface shape of the mirror portion is changed by applying a voltage to the piezoelectric element, the portion where the mirror surface shape greatly changes is the arrow portion in FIG. 6A where the electrode 5a is arranged. Therefore, by forming the temperature detecting means 10 in the vicinity of the mirror fixing portion 3 of the mirror substrate 6, the temperature detecting means 10 can reduce the generation of the internal stress caused by the change of the mirror surface shape when a voltage is applied to the piezoelectric element. Can be avoided. Therefore, it is possible to prevent a change in the resistance value of the metal thin-film resistor in the temperature detecting means, and to measure the ambient temperature substantially accurately.
[0043]
As shown in FIG. 6B or FIG. 6C, the temperature detecting means 10 used in the present embodiment includes a metal thin film resistor 12, a metal thin film formed of a metal whose resistance value fluctuates due to a temperature change. It includes an adhesion layer 11 formed of an insulating film for adhering the resistor 12 to the mirror substrate 6, and a protective film 13 covering the metal thin film resistor 12 with the adhesion layer 11 and protecting the metal thin film resistor 12.
[0044]
The manufacturing method of the temperature detecting means 10 used in the present embodiment is as follows. 2 The surface of the insulating film, which is 2 3.) An adhesion layer 11 having improved adhesion to the metal thin film resistor 12 is formed by plasma treatment, back sputtering, or ion implantation of argon (Ar) or silicon (Si). In order to further improve the adhesion between the adhesion layer 11 and the metal thin film resistor 12, as shown in FIG. 6C, a recess is formed on the surface of the adhesion layer 11, and the metal thin film resistor is formed inside the recess. It is preferable to form No. 12.
[0045]
Next, the metal thin film resistor 12 is formed on the adhesion layer 11 mainly by a sputtering method. The thin film of the metal thin-film resistor 12 is an aggregate of grains, and an interface (grain boundary) between these grains has an irregular resistance. Here, when stress (film displacement) occurs in the thin film of the metal thin film resistor 12, the irregular resistance of the grain boundary increases. Therefore, when the thin film of the metal thin-film resistor 12 is used for detecting a temperature change, it is necessary to prevent stress from being generated in the thin film of the metal thin-film resistor 12. In other words, when a voltage is applied to the piezoelectric element 2 to change the mirror surface shape of the deformable mirror, the mirror is used in order to avoid the occurrence of stress in the metal thin film resistor 12 due to the change in the mirror surface shape such as the uneven shape. It is desirable not to form the temperature detecting means 10 in a portion where the mirror surface shape changes in the portion. In addition, a change in the mirror surface shape of the deformable mirror may cause stress migration in the metal thin-film resistor 12. Therefore, in order to ensure long-term reliability in temperature measurement of the temperature detecting unit 10, the mirror unit is required. It should be avoided to form the temperature detecting means 10 in the portion where the mirror surface shape changes.
[0046]
Finally, a protective film 13 made of an insulating film is formed on the metal thin film resistor 12 and the adhesion layer 11, and the metal thin film resistor 12 is covered with the adhesion layer 11 and the protection film 12, thereby completing the temperature detecting means 10.
[0047]
In this embodiment, since the temperature detecting means 10 is formed only on a part of the mirror substrate 6, the reflection film of the shape-variable mirror includes the adhesion layer 11, the metal thin film resistor 12 And the film stress of the protective film 13 is not substantially affected. Therefore, in the deformable mirror according to the present embodiment, it is possible to substantially prevent the initial mirror surface shape of the deformable mirror from being distorted, and that the change in the initial plane shape of the mirror portion due to a change in ambient temperature is emphasized. it can.
[0048]
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0049]
The deformable mirror according to the present embodiment has the same configuration as the deformable mirror according to the above-described first embodiment, except that the metal thin film resistor 12 is made of a Pt thin film, and the adhesion layer 11 and the protective film 13 are respectively formed. Silicon nitride (Si 3 N 4 ) Film or tantalum pentoxide (Ta) 2 O 5 ) Made of film.
[0050]
The Pt thin film as the metal thin film resistor 12 is formed by a sputtering method. By changing the sputtering conditions, the temperature coefficient of resistance (TCR) of the metal thin film resistor 12 can be freely changed to some extent. Can be made. For example, when forming the metal thin film resistor 12, by lowering the power of the sputtering apparatus and setting the temperature of the mirror substrate 6 high, a metal thin film resistor having a high resistance temperature coefficient can be obtained. In this way, a highly sensitive metal thin-film resistor 12 having a large change in resistance value with respect to a temperature change is formed.
[0051]
When the metal thin film resistor 12 is a Pt thin film, the adhesion layer 11 and the protective film 13 of the temperature detecting means 10 are formed of SiO. 2 When the film is used, SiO 2 Since the film has poor adhesion to Pt, it is difficult to ensure the reliability of temperature measurement by the temperature detecting means 10. In order to improve the adhesion between the adhesion layer 11 and the protective film 13 and the metal thin film resistor 12, SiO 2 is used as the adhesion layer 11 and the protective film 13. 2 Si instead of film 3 N 4 Membrane or Ta 2 O 5 It is desirable to use a membrane. Further, before forming a Pt thin film as the metal thin film resistor 12 on the adhesion layer 11, the adhesion between the adhesion layer 11 and the metal thin film resistor 12 is further improved by performing a back sputtering process on the adhesion layer 11. be able to.
[0052]
Here, a method for manufacturing the temperature detecting means 10 according to the present embodiment will be described. First, a 0.3 μm-thick Ta for forming the adhesion layer 11 is formed on the surface of the mirror substrate 6 opposite to the mirror surface. 2 O 5 The film was formed by a sputtering method, and a Pt thin film having a thickness of 0.2 μm for continuously forming the metal thin film resistor 12 was formed by a sputtering method. Next, 0.2 μm Ta is used as a mask material for forming the metal thin film resistor 12 from the Pt thin film. 2 O 5 A film was formed. This mask material is patterned according to the desired shape of the metal thin film resistor 12 (including a portion for connecting a means for measuring the resistance value of the metal thin film resistor 12, that is, a bonding pad) by a photolithographic method. By performing back sputtering, the Pt thin film was etched into a desired metal thin film resistor shape. Then, a 0.3 μm thick Ta 2 O 5 The film was formed by a sputtering method. Next, Ta for forming the adhesion layer 11 and the protective film 13 is formed by photolithography. 2 O 5 The film is patterned into a shape of a portion of the mirror substrate 6 where the temperature detecting means 10 is formed (hereinafter, referred to as a temperature detecting means forming area for simplicity). Finally, Ta for forming the adhesion layer 11 and the protective film 13 is used. 2 O 5 The temperature detecting means 10 in the present embodiment is completed by removing all portions of the film other than the temperature detecting means forming region by etching. At the time of this patterning and etching, a hole for connecting the bonding pad of the metal thin-film resistor 12 to the means for measuring the resistance value of the metal thin-film resistor 12 is formed in the protective film 13 at the same time (the bonding pad is formed). Window open).
[0053]
Next, the operation of the temperature detecting means 10 in the present embodiment will be specifically described with reference to FIG. FIG. 7 shows a form of the temperature detecting means 10 and the metal thin film resistor 12 in the present embodiment.
[0054]
In the present embodiment, the Pt thin film having a TCR of 3200 ppm / ° C. was obtained by setting the temperature of the mirror substrate to 300 ° C. and setting the power of the sputtering apparatus to 200 W as the conditions for forming the Pt thin film. As shown in FIG. 7, the metal thin-film resistor 12 excluding the bonding pads (both ends of the metal thin-film resistor 12) is formed linearly, and its dimensions are as follows: line width 4 μm, line length 30 mm, film thickness 0. If it is 2 μm, the overall resistance value of the metal thin-film resistor 12 is about 5000Ω. Here, since the bonding pad is usually larger than the portion other than the bonding pad of the metal thin film resistor 12, the resistance value of the bonding pad can be ignored. Further, since the TCR is 3200 ppm / ° C., when the temperature changes by 1 ° C., the resistance value changes by about 16Ω. For example, assuming that a constant current of 0.5 mA flows through the metal thin film resistor, the voltage of the metal thin film resistor becomes 2.5 V, and when the temperature changes by 1 ° C., the amount of change in the voltage is about 8 mV. Since the amount of change in the voltage corresponds to the change in the temperature, the ambient temperature can be measured by applying a constant current to the metal thin film resistor 12 and measuring the voltage. This resistance value is merely an example, and the shape of the metal thin-film resistor 12, that is, the length and the cross-sectional area, can be designed to some extent freely under the restriction by the size of the temperature detecting means 10 and the bonding pad. it can. Therefore, the metal thin film resistor can be designed to some extent freely in consideration of improvement in sensitivity (amount of voltage change with respect to temperature change) and a decrease in voltage measurement accuracy due to incorrect resistance such as wiring resistance.
[0055]
Also, as shown in FIG. 7, the area of the metal thin film resistor 12 can be made quite small, such as 7 mm × 0.15 mm, even if the bonding pads are combined. By installing the mirror portion on the side where the mirror surface shape changes little, long-term reliability in temperature measurement by the temperature detecting means can be obtained. The size of the temperature detecting means 10 is merely one example, and the length of the temperature detecting means 10 can be shortened by increasing the number of turns in the shape of the metal thin film resistor 12. Thereby, the temperature detecting means 10 adapted to the size of the mirror portion of the deformable mirror can be freely designed to some extent.
[0056]
Next, a third embodiment of the present invention will be described with reference to FIG.
[0057]
The deformable mirror according to the present embodiment shown in FIG. 8A has a configuration similar to that of the conventional deformable mirror having a normal structure shown in FIG. 2, except that the temperature detecting means 10 is provided on the side opposite to the mirror surface of the mirror section. It is arranged in the vicinity of the mirror fixing part 3 or in the peripheral part of the mirror part. In FIG. 8A, the width of the temperature detecting means 10 is drawn large, but actually, as shown in FIG. 7, the width of the temperature detecting means 10 is as small as 0.15 mm. Therefore, the ratio of the area of the temperature detecting means 10 to the area of the mirror portion is small. By arranging the temperature detecting means 10 in the vicinity of the mirror fixing part 3 or in the peripheral part of the mirror part, even if the mirror surface shape of the mirror part is changed by expansion and contraction of the piezoelectric element 2, the temperature detecting means 10 is almost deformed. Without this, it is possible to provide the temperature detecting means 10 capable of measuring the temperature with high accuracy and ensuring long-term reliability.
[0058]
Further, the deformable mirror in the present embodiment shown in FIG. 8B has a configuration similar to that of the conventional thin film structure deformable mirror shown in FIG. 3, but the temperature detecting means 10 is opposite to the mirror surface of the mirror section. It is arranged between the slit 9 and the projection 14 on the side. The portion of the mirror outside the slit 9 hardly deforms even if the mirror surface shape of the mirror changes due to expansion and contraction of the piezoelectric element 2. Therefore, if the temperature detecting means is disposed between the slit 9 and the convex portion 14 on the side opposite to the mirror surface of the mirror portion, even if the mirror surface shape of the mirror portion is deformed due to the expansion and contraction of the piezoelectric element 2, the temperature detecting means is not heated. The detecting means 10 is hardly deformed, can measure the temperature with high accuracy, and can provide the temperature detecting means 10 with long-term reliability.
[0059]
Next, a fourth embodiment of the present invention will be described.
[0060]
One deformable mirror in this embodiment has a configuration similar to that of the conventional deformable mirror having a normal structure shown in FIG. 2, but the temperature detecting means 10 corresponds to the mirror fixing section 3 on the mirror surface side of the mirror section. Placed in place. Thus, by disposing the temperature detecting means 10 at a position corresponding to the mirror fixing portion 3 on the mirror surface side of the mirror portion, even if the mirror surface shape of the mirror portion is changed by expansion and contraction of the piezoelectric element 2, the temperature detecting means 10 The temperature detecting device 10 can measure the temperature with higher accuracy without any deformation, and can provide the temperature detecting device 10 with long-term reliability.
[0061]
Another deformable mirror according to the present embodiment has a configuration similar to that of the conventional deformable mirror having a thin film structure shown in FIG. 3, except that the temperature detecting means 10 is provided at a location corresponding to the convex portion 14 on the mirror side of the mirror portion. Has been placed. Thus, by disposing the temperature detecting means 10 at a position corresponding to the convex portion 14 on the mirror side of the mirror section, even if the mirror surface shape of the mirror section is changed by expansion and contraction of the piezoelectric element 2, the temperature detecting section 10 Does not deform at all, can measure the temperature with even higher accuracy, and can provide the temperature detecting means 10 with long-term reliability secured. In addition, since the temperature detecting means 10 is formed on the mirror surface side of the flat mirror portion, it is easy to manufacture the temperature detecting means 10. Specifically, the temperature detecting means 10 can be manufactured using contact exposure in a photolithographic method. In the case where the temperature detecting means 10 is formed on the mirror side of the mirror portion as in the deformable mirror according to the present embodiment, usually, the temperature detecting means 10 is formed on the mirror substrate 6 and then the reflection film 1 is mirrored. A film is formed on the substrate 6 (and the temperature detecting means 10).
[0062]
Here, if the temperature detecting means 10 is manufactured inside the convex portion 14 on the side opposite to the mirror surface of the mirror portion, the deformable mirror having the thin film structure has a concave portion on the side opposite to the mirror surface of the mirror portion. It is difficult to pattern a thin metal thin film resistor having a line width of 4 μm by contact exposure in a photolithographic method. That is, if patterning is performed by contact exposure in the photolithographic method, the distance between the photomask and the mask material for forming the metal thin film resistor is about 200 μm, so that the pattern of the metal thin film resistor is unclear on the mask material. Exposure. The metal thin-film resistor must have an accurate resistance value. If the pattern of the metal thin-film resistor is unclearly exposed on a mask material, the metal thin-film resistor must be accurately formed into a desired shape. Can not. Therefore, a metal thin-film resistor having an accurate resistance value cannot be obtained, and a temperature detecting means capable of detecting an accurate temperature cannot be provided. On the other hand, in order to form the metal thin film resistor into a desired shape inside the convex portion 14 on the side opposite to the mirror surface of the mirror portion, stepper exposure is advantageous. Capital investment is higher and costs are higher than exposure.
[0063]
Next, a fifth embodiment of the present invention will be described with reference to FIG.
[0064]
The deformable mirror according to the present embodiment shown in FIG. 9A has a configuration similar to that of the conventional deformable mirror having a normal structure shown in FIG. 2, except that the temperature detecting means 10 is provided on the side opposite to the mirror surface of the mirror section. It is arranged inside the mirror fixing part 3. Further, the deformable mirror according to the present embodiment shown in FIG. 9B has a configuration similar to the conventional deformable mirror having a thin film structure shown in FIG. 3, but the temperature detecting means 10 is opposite to the mirror surface of the mirror section. On the side convex portion 14.
[0065]
As shown in FIGS. 9A and 9B, by disposing the temperature detecting means 10 inside the mirror fixing part 3 or on the convex part 14, the mirror surface shape of the mirror part changes due to expansion and contraction of the piezoelectric element 2. Even if it does, the temperature detecting means 10 does not deform at all, can measure the temperature with high accuracy, and can provide the temperature detecting means 10 with long-term reliability secured. Further, since the temperature detecting means 10 is sandwiched between the mirror part and the mirror fixing member, the initial state of the deformable mirror due to the film stress of the temperature detecting means 10 caused by forming the temperature detecting means 10 in the mirror part. Mirror-like distortion can be removed. Here, in order to connect the temperature detecting means 10 sandwiched between the mirror portion and the mirror fixing member and the means for measuring the resistance value of the metal thin film resistor 12 of the temperature detecting means 10, a metal thin film resistor Twelve bonding pads 10 ′ are formed extending to portions other than the mirror fixing portion 3 or the convex portion 14. Further, in the deformable mirror having the thin film structure shown in FIG. 9B, since the temperature detecting means 10 is formed on the convex portion 14, it is possible to use inexpensive photolithographic contact exposure.
[0066]
Next, a sixth embodiment of the present invention will be described.
[0067]
The deformable mirror according to the present embodiment has a configuration similar to that of the conventional deformable mirror shown in FIG. 2 or FIG. 3, but the temperature detecting means 10 is provided at a location corresponding to the mirror fixing portion 3 on the mirror surface side of the mirror. It is arranged at a location corresponding to the convex portion 14. As described above, by disposing the temperature detecting means 10 at the location corresponding to the mirror fixing portion 3 or the location corresponding to the convex portion 14 on the mirror side of the mirror portion, the mirror surface shape of the mirror portion is expanded and contracted by the piezoelectric element 2. Even if the temperature is changed, the temperature detecting means 10 does not deform at all, can measure the temperature with high accuracy, and can provide the temperature detecting means 10 with long-term reliability secured. Further, since the temperature detecting means 10 is disposed in a portion of the mirror portion where the mirror shape is not deformed, distortion of the initial mirror surface shape of the deformable mirror due to the film stress of the temperature detecting means 10 can be removed. Further, by disposing the temperature detecting means 10 on the mirror surface side of the mirror portion, it is not necessary to form the temperature outside the bonding pad temperature detecting means forming area. 10 can be connected to means for measuring the resistance value of the metal thin film resistor 12 of the temperature detecting means 10.
[0068]
Next, a seventh embodiment of the present invention will be described.
[0069]
In the deformable mirror according to the present embodiment, in the fourth embodiment and the sixth embodiment, an area (temperature detecting means forming area) where the reflection film 1 and the temperature detecting means 10 are formed on the mirror substrate 6 is formed. Are separated. The reflection film 1 is formed of a metal thin film such as gold (Au) having a high reflectance or a dielectric multilayer film, and is usually formed on the entire mirror surface. However, in a deformable mirror having a structure in which the temperature detecting means 10 is formed on the mirror surface side of the mirror portion, if the reflective film 1 is also formed on the temperature detecting means 10, the temperature detecting means In some cases, stress is generated in the metal thin film resistor 12 of 10 and the resistance value changes. In particular, when the reflection film 1 is formed of a dielectric multilayer film, the reflection film 1 is a laminated film of about 30 layers having a thickness of about 3 μm in order to realize the reflection film 1 having a desired reflectance. In some cases. Further, since the temperature detecting means 10 is connected to the means for measuring the resistance value of the metal thin film resistor 12 of the temperature detecting means 10, it is desirable that nothing exists on the temperature detecting means 10. By separating the area on the mirror substrate 6 where the reflective film 1 and the temperature detecting means 10 are formed, the resistance of the metal thin film resistor 12 of the temperature detecting means 10 changes due to the film stress of the reflective film 1. Can be provided, and a deformable mirror having temperature detecting means capable of accurately measuring the temperature can be provided.
[0070]
In the present embodiment, in the deformable mirror in which the reflection film 1 is separated from the temperature detecting means forming area on the mirror substrate 6, first, a temperature detecting means is prepared in advance in the temperature detecting means forming area on the mirror substrate 6. Thereafter, when the reflective film 1 is formed on the mirror substrate by sputtering, the reflective film 1 is separated from the temperature detection unit forming region by using vapor deposition using a metal mask without adding a new process. Can be formed. As shown in FIG. 7, the area of the detecting means forming area can be made very small as compared with the area of the mirror part, so that a new space for the temperature detecting means forming area is provided on the mirror substrate 6. No need to secure.
[0071]
Next, an eighth embodiment of the present invention will be described with reference to FIG.
[0072]
The deformable mirror according to the present embodiment is different from the deformable mirror having the thin film structure according to the third embodiment shown in FIG. 3B in that it is connected to the metal thin film resistor 12 of the temperature detecting means 10 formed on the projection 14. The width of the wiring to be formed is wider than the length or width of the bonding pad of the metal thin film resistor 12. In the deformable mirror having the thin film structure shown in FIG. 3B, when wiring for the temperature detecting means 10 is formed on the surface opposite to the mirror surface of the mirror portion, as shown in FIG. Wirings 10 ′ are formed on the projections 14, and these wirings 10 ′ are attached to the mirror fixing members 8 by using a conductive adhesive or bumps on the surfaces of the projections 14 that contact the mirror fixing members 8. It is electrically connected to the formed wiring.
[0073]
However, as shown in FIG. 10B showing a cross section taken along line bb ′ in FIG. 10A, the boundary between the side surface of the convex portion 14 and the surface that contacts the mirror fixing member 8, The thickness of the wiring 10 'becomes thin, and the resistance value increases at this boundary. When the ambient temperature is detected by using the metal thin film resistor 12 of the temperature detecting means 10, ideally, a temperature detecting means having a large dynamic range is realized by eliminating illegal resistance such as wiring. be able to. Therefore, the increase in the resistance value generated at the boundary difference portion is not desirable. In the deformable mirror according to the present embodiment, as shown in FIG. 10C, the width of the wiring 10 ′ formed on the projection 14 and connected to the metal thin film resistor 12 of the temperature detecting means 10 is changed to the metal thin film resistance. It is wider than the length or width of the bonding pad of the body 12. As a result, even if the thickness of the wiring 10 ′ becomes thinner at the boundary between the side surface of the convex portion 14 and the surface in contact with the mirror fixing member 8, the width of the wiring 10 ′ becomes wider. It is possible to prevent an increase in the resistance value in the portion. For example, even if the film thickness at the boundary portion of the wiring 10 ′ becomes half of the film thickness at the other portion, the width of the wiring is doubled as the normal width, thereby preventing an increase in the resistance value at the boundary portion. be able to. The width of the wiring 10 ′ is desirably wide, but the width of the wiring 10 ′ should be determined in consideration of the balance of the entire design of the deformable mirror. Further, since the width of the wiring 10 ′ is large, the wiring 10 ′ can be easily formed on the projection 14.
[0074]
Next, a ninth embodiment of the present invention will be described with reference to FIG.
[0075]
The deformable mirror according to this embodiment has a resistance value of 1 kΩ to 10 kΩ when the Pt thin film is used as the metal thin film resistor in all the above embodiments.
[0076]
Assuming that the room temperature (25 ° C.) is a reference for the ambient temperature, the resistance R measured by the temperature detecting means at the room temperature 25 Is given by the following equation 1.
R 25 = Rs + R 1 ... (Equation 1)
Is represented by Here, Rs is the resistance value of the metal thin film resistor at room temperature, R 1 Is the value of the improper resistance due to wiring and the like.
[0077]
The resistance value R measured by the temperature detecting means when the ambient temperature changes by 1 ° C. (26 ° C.) 26 Is given by Equation 2
R 26 = Rs + R 1 + (Rs × TCR × 1 (° C.)) (Equation 2)
Is represented by Here, TCR is a temperature coefficient of resistance.
[0078]
From Equations 1 and 2, the resistance value changes almost linearly with temperature. Here, the value R of the illegal resistance 1 Is desirably negligibly smaller than the resistance value Rs of the metal thin film resistor. When the value of the illicit resistance increases, the change in the resistance value measured by the temperature detecting means with respect to the temperature change decreases, and the sensitivity for detecting the temperature decreases. Therefore, the resistance value Rs of the metal thin-film resistor is usually equal to the value R 1 And the resistance value measured by the temperature detecting means with respect to the temperature is greatly changed. However, if the resistance value Rs of the metal thin-film resistor is too large, the voltage required for flowing a constant current through the metal thin-film resistor must be increased. Therefore, the resistance value Rs of the metal thin film resistor needs to be set to an appropriate value.
[0079]
Here, it is assumed that the illicit resistance is negligibly small compared to the resistance value of the metal thin film resistor, the TCR is 3200 ppm / ° C., and the resistance value of the metal thin film resistor at room temperature is 1 kΩ, and the metal thin film resistor is designed. Assuming that a constant current of 1 mA flows through the metal thin film resistor at room temperature, the required voltage is about 1 V. The change in the resistance value measured by the temperature detecting means when the temperature changes by 1 ° C. is 3.2 Ω from Equations 1 and 2, and the change in voltage is 3.2 mV. Similarly, the metal thin-film resistor is designed such that the illicit resistance is negligibly smaller than the resistance value of the metal thin-film resistor, the TCR is 3200 ppm / ° C., and the resistance value of the metal thin-film resistor at room temperature is 10 kΩ. In this case, if a constant current of 0.3 mA flows through the metal thin film resistor at room temperature, the required voltage is about 3V. When the temperature changes by 1 ° C., the change in the resistance value measured by the temperature detecting means is 32Ω, and the change in the voltage is 9.6 mV.
[0080]
The above design conditions were determined so that the voltage of the power supply of the optical pickup device was 5 V, and the voltage applied to the metal thin-film resistor was lower than the voltage of the power supply. Assuming that the resistance value of the metal thin-film resistor at room temperature is 1 kΩ to 10 kΩ, the electric power required to flow the above constant current through the metal thin-film resistor is 1 mVA to 9 mVA. Therefore, when the deformable mirror provided with the temperature detecting means is used in an optical pickup device, if the resistance value of the metal thin film resistor in the temperature detecting means at room temperature is within the range of 1 kΩ to 10 kΩ, the temperature change is detected. It is possible to provide a deformable mirror with temperature detecting means that balances sensitivity and power consumption.
[0081]
【The invention's effect】
According to the present invention, there is provided a deformable mirror and an optical pickup device having the deformable mirror, which have a temperature detecting means capable of substantially accurately measuring the ambient temperature, have a small initial planar shape distortion. An optical disk information input / output device can be provided.
[0082]
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams illustrating the generation of coma due to tilt of an optical disk, wherein FIG. 1A is a diagram for a CD and FIG. 1B is a diagram for a DVD.
FIG. 2 is a cross-sectional view of a conventional deformable mirror having a normal structure.
3A and 3B are diagrams showing a conventional deformable mirror having a thin film structure, in which FIG. 3A is a plan view of a mirror fixing member removed and viewed from a side opposite to a reflection film, and FIG. It is a sectional view in the AA 'direction of a), and (c) is a figure explaining change of a mirror surface shape.
FIG. 4 is a contour diagram of wavefront aberration of laser light generated by tilt.
5A and 5B are diagrams illustrating reduction of wavefront aberration of laser light in the AA ′ direction of the deformable mirror, wherein FIG. 5A is a diagram illustrating a wavefront aberration of laser light generated by tilt, and FIG. FIG. 3C is a wavefront aberration diagram generated by the deformable mirror, and FIG. 4C is a wavefront aberration diagram after the wavefront aberration has been reduced by the deformable mirror.
FIGS. 6A and 6B are diagrams illustrating a deformable mirror according to the first and second embodiments of the present invention. FIG. 6A is a diagram of a deformable mirror in which a temperature detecting unit is provided in a deformable mirror having a normal structure. (B) is a diagram of a deformable mirror having a thin film structure and a temperature detecting means provided on the deformable mirror.
FIG. 7 is a diagram illustrating a temperature detecting means of the deformable mirror according to the present invention.
8A and 8B are diagrams illustrating a deformable mirror according to a third embodiment of the present invention, wherein FIG. 8A is a diagram of a deformable mirror in which a temperature detecting unit is provided on a deformable mirror having a normal structure, and FIG. FIG. 3 is a view of a deformable mirror provided with a temperature detecting means on the deformable mirror having a thin film structure.
9A and 9B are diagrams illustrating a deformable mirror according to a fifth embodiment of the present invention, in which FIG. 9A is a diagram of a deformable mirror in which a temperature detecting unit is provided on a deformable mirror having a normal structure, and FIG. FIG. 3 is a view of a deformable mirror provided with a temperature detecting means on the deformable mirror having a thin film structure.
FIGS. 10A and 10B are diagrams illustrating a deformable mirror according to an eighth embodiment of the present invention, wherein FIG. 10A is a diagram of a deformable mirror in which wiring for a narrow temperature detecting unit is formed, and FIG. , (A) and (c) are cross-sectional views along the line bb ′, and (c) is a view of the deformable mirror on which wires for a wide temperature detecting means are formed.
[Explanation of symbols]
1 Mirror material, reflective film
2 Piezoelectric element
3 Mirror fixing part
4a, 5a electrode
4b, 4c, 5b, 5c Wiring
6 Mirror substrate
7 Insulating film
8 Mirror fixing members
9 slit
10 Temperature detection means
10 'wiring, bonding pad
11 Adhesion layer
12 Metal thin film resistor
13 Protective film
14 convex
101a, 101b Objective lens
102a, 102b resin layer
103a, 103b spot
108 recording layer

Claims (11)

鏡部の鏡面の形状が可変な形状可変鏡において、
該形状可変鏡の周囲の温度を検知する温度検知手段を有し、
該温度検知手段は、前記鏡部の前記鏡面の形状が変化しない部分に設けられることを特徴とする形状可変鏡。In a deformable mirror in which the shape of the mirror surface of the mirror section is variable,
Having a temperature detecting means for detecting a temperature around the deformable mirror,
The deformable mirror according to claim 1, wherein the temperature detecting means is provided at a portion of the mirror portion where the shape of the mirror surface does not change. 鏡部の鏡面の形状が可変な形状可変鏡において、
該形状可変鏡の周囲の温度を検知する温度検知手段を有し、
該温度検知手段は、前記鏡部の前記鏡面の形状が変化しない部分に一体に設けられることを特徴とする形状可変鏡。In a deformable mirror in which the shape of the mirror surface of the mirror section is variable,
Having a temperature detecting means for detecting a temperature around the deformable mirror,
The deformable mirror is characterized in that the temperature detecting means is provided integrally with a portion of the mirror portion where the shape of the mirror surface does not change. 前記鏡部の鏡面の形状は、前記鏡部の前記鏡面と反対側に設けられた圧電素子の伸縮によって変化させられ、
前記温度検知手段は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分及び前記圧電素子が設けられる部分の間、に配置されることを特徴とする請求項１又は２記載の形状可変鏡。The shape of the mirror surface of the mirror portion is changed by expansion and contraction of a piezoelectric element provided on the side opposite to the mirror surface of the mirror portion,
The temperature detecting means is arranged between a portion where a member supporting the mirror portion is in contact with the mirror portion and a portion where the piezoelectric element is provided, on a side opposite to the mirror surface of the mirror portion. The deformable mirror according to claim 1 or 2, wherein 前記鏡部の鏡面の形状は、前記鏡部の前記鏡面と反対側に設けられた圧電素子の伸縮によって変化させられ、
前記温度検知手段は、前記鏡部の前記鏡面側の、前記鏡部の前記鏡面と反対側で前記鏡部を支持する部材が前記鏡部と接触する部分及び前記鏡部の前記鏡面と反対側で前記圧電素子が設けられる部分の間、に配置されることを特徴とする請求項１又は２記載の形状可変鏡。The shape of the mirror surface of the mirror portion is changed by expansion and contraction of a piezoelectric element provided on the side opposite to the mirror surface of the mirror portion,
The temperature detecting means is provided on the mirror surface side of the mirror portion, on a side opposite to the mirror surface of the mirror portion, where a member supporting the mirror portion is in contact with the mirror portion, and on a side opposite to the mirror surface of the mirror portion. The deformable mirror according to claim 1, wherein the deformable mirror is disposed between portions where the piezoelectric element is provided. 前記温度検知手段は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分、に配置されることを特徴とする請求項１又は２記載の形状可変鏡。The shape according to claim 1, wherein the temperature detection unit is arranged at a portion of the mirror portion opposite to the mirror surface, at a portion where a member supporting the mirror portion comes into contact with the mirror portion. 4. Variable mirror. 前記温度検知手段は、前記鏡部の前記鏡面側の、前記鏡部の前記鏡面と反対側で前記鏡部を支持する部材が前記鏡部と接触する部分、に配置されることを特徴とする請求項１又は２記載の形状可変鏡。The temperature detecting means is arranged on the mirror surface side of the mirror portion, at a portion opposite to the mirror surface of the mirror portion, where a member supporting the mirror portion contacts the mirror portion. The deformable mirror according to claim 1. 前記鏡部は、前記鏡部の前記鏡面側に前記形状可変鏡に入射する光を反射する反射膜を含み、
前記温度検知手段は、前記鏡部の前記反射膜が設けられてない部分に配置されることを特徴とする請求項４又は６記載の形状可変鏡。The mirror unit includes a reflection film that reflects light incident on the shape-variable mirror on the mirror surface side of the mirror unit,
The deformable mirror according to claim 4, wherein the temperature detecting unit is disposed in a portion of the mirror unit where the reflection film is not provided. 前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触する部分は、前記鏡部の前記鏡面と反対側の、前記鏡部を支持する部材が前記鏡部と接触しない部分に対する凸部であり、
前記温度検知手段は、該温度検知手段を駆動する電圧を印加する電極を有し、
前記温度検知手段の前記電極に接続される配線は、少なくとも前記凸部に設けられ、
前記配線の前記凸部における幅は、前記電極の幅よりも広いことを特徴とする請求項３又は５記載の形状可変鏡。The portion of the mirror portion opposite to the mirror surface, where the member supporting the mirror portion contacts the mirror portion, the member of the mirror portion opposite to the mirror surface that supports the mirror portion is the mirror portion. Is a convex portion for a portion that does not contact with
The temperature detecting means has an electrode for applying a voltage for driving the temperature detecting means,
A wire connected to the electrode of the temperature detection means is provided at least on the protrusion,
The deformable mirror according to claim 3, wherein a width of the wiring at the convex portion is wider than a width of the electrode. 前記温度検知手段は、白金からなる薄膜の抵抗体、及び前記抵抗体の少なくとも一部分を覆う五酸化二タンタル又は窒化シリコンからなる絶縁層を含むことを特徴とする請求項１乃至８いずれか１項記載の形状可変鏡。9. The temperature detecting means according to claim 1, further comprising a thin-film resistor made of platinum and an insulating layer made of tantalum pentoxide or silicon nitride covering at least a part of the resistor. The deformable mirror as described. 前記抵抗体の抵抗値は、１ｋΩ乃至１０ｋΩであることを特徴とする請求項９記載の形状可変鏡。The deformable mirror according to claim 9, wherein the resistance value of the resistor is 1 kΩ to 10 kΩ. 請求項１乃至１０いずれか１項記載の形状可変鏡を有する光ピックアップ装置を備えることを特徴とする光ディスク情報入出力装置。An optical disc information input / output device comprising an optical pickup device having the deformable mirror according to any one of claims 1 to 10.
JP2002175893A 2002-06-17 2002-06-17 Shape variable mirror and optical disk information input and output device Pending JP2004020940A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011221402A (en) * 2010-04-13 2011-11-04 Mitsubishi Electric Corp Deformable mirror
JP2015008031A (en) * 2013-06-24 2015-01-15 シーゲイト テクノロジー エルエルシー Device including at least one adhesion layer and method of forming adhesion layer

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011221402A (en) * 2010-04-13 2011-11-04 Mitsubishi Electric Corp Deformable mirror
JP2015008031A (en) * 2013-06-24 2015-01-15 シーゲイト テクノロジー エルエルシー Device including at least one adhesion layer and method of forming adhesion layer

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