JP3725817B2 - Aspheric lens decentration measuring method and decentration measuring apparatus - Google Patents

Description

【００２７】
この受け面1aの反対面1bの近軸曲率中心位置は図２(g)に示すように、
【数２】

という換算式を用いて演算部8で求める。
【００２８】
つづいて、変位センサ部6を被検レンズ1の被検面1bに応じてその検出軸10の角度を被検面1bの法線に一致させ、変位センサ部6の検出軸10方向の高さも被検レンズ1の被検面1bに応じて調整する。その状態で被検レンズ1を回転レンズ支持部材4により回転させて、検出軸10方向の高さの変化を、回転角測定部7により被検レンズ1の角度変化を出力し、両者を演算部8に入力する。
演算部8では、被検面形状測定部(変位センサ部)6の検出値を回転レンズ支持部材4の回転軸9の方向に変換する。
【００２９】
被検面形状測定部(変位センサ部)6の検出軸10の角度の支点位置と被検レンズ1の位置関係より、図１に示す測定半径rが算出される。この測定半径rと回転角測定部7の情報と被検面形状測定部(変位センサ部)6の出力を回転軸9方向に分解した情報より、ｘ，ｙ，ｚ座標の三次元座標データに換算する。測定部の出力信号に基づくこの三次元座標データと該被検面1bの設計上の式（設計式）を対比させる（参照：図４のＳ２０）。
この時に被検面形状測定部(変位センサ部)6の検出軸10は、回転軸9に対して傾いた構成となっているので、設計式との比較を行なう為には、回転軸方向の変位への変換を行なう必要がある。
【００３０】
【数３】

【００３１】
回転軸9からrだけ離れたポイントで非球面軸検出を行なう場合には、(5)式で示される高さ方向の情報を、次式により、ｘ，ｙに分離して設計式と比較を行なう。ここでは、各測定ポイントに対する回転角測定部7の出力をθrotとする。
【数４】

【００３２】
なお、図１では検出軸10が回転軸9に対して傾いた場合を例示しているが、この傾きθは０度、即ち回転軸9に対して平行な状態で、被検面形状測定部(変位センサ部)6の検出軸10を構成しても上記と同様な計算が成り立つ。
【００３３】
上述した三次元座標データと設計式とを比較する具体的方法としては、例えば、測定三次元データを被検面1bの設計式上でシフトまたはチルトさせて、両者の差が最も小さくなるように調整を行なえばよい。即ち、シフト量として(1)，(2)式で与えられる量をそれぞれｘ，ｙ別に代入し、ｘ方向とｙ方向のシフトを固定し、球心位置を中心としてｘ方向とｙ方向にチルトおよびｚ方向にシフトさせて、両者の差が最小となる状態を検出する。
【００３４】
その後、測定三次元データのチルト量およびシフト量より逆算すれば、回転軸９に対する受け面の反対面１ｂの非球面面頂のｘｙ平面における移動量１ｔｂを求めることができる（参照：図４のＳ３０）。
図３（ａ）、（ｂ）を参照して、上記チルト量およびシフト量について説明すると、図３（ａ）、（ｂ）で例示のように、上記計算で求めたｘ方向のチルト量をＡｂｘ，ｙ方向のチルト量をＡｂｙとすると、非球面面頂のシフト量１tbxおよび１tbyは次式で求められる。
【数５】

【００３５】
さらに演算部8は、被検レンズ1の両面の近軸曲率中心位置と被検面1bの面頂位置とのデータにより、被検面1bの非球面偏心量εb及びその方向θεbを算出する（参照：図４のＳ４０）。
この算出方法を図２(a)〜(g)を用いて、その手順を詳しく説明する。
第１のステップとして、受け面1aの近軸曲率中心位置1oaと、受け面の反対面1bの近軸曲率中心値1obを図２(d)及び(g)に示すようにそれぞれｘ、ｙの値に分解する。それぞれの数値は(1)〜(4)式と同様な式にて得られる。
【００３６】
第２のステップとして、両面の近軸曲率中心偏心量を考慮して、図２（ａ）におけるｚ軸上での１oaから１obまでの高さＺoを算出する。この高さＺoは次式による。
【数６】

ここでｒａは受け面１ａの近軸曲率半径、ｒｂは受け面１ｂの近軸曲率半径、ｄはレンズ肉厚を表わす。
【００３７】
第３のステップとして、受け面の反対面1bの面頂シフト量と受け面の偏心量とを考慮して、図２(a)におけるz軸上での1obから1tbまでの高さZbを算出する。また、高さZbは次式による。
【数７】

【００３８】
以降のステップにおいては、xz平面とyz平面に分けて計算を行なうことになる。ここでは一例として先にxz平面上での計算を行ない、その後にyz平面の計算を行なうものとするが、説明の便宜上でそのように行なうのであって、yz平面を先に計算してもよいし、各ステップにおいてxz平面とyz平面を交互に計算を行なってもよい。
【００３９】
第４のステップとして、ｘｚ平面でのｚ軸に対する非球面軸ｒｂｘと光軸１oax−１obxの傾きとから非球面軸偏心のｘ成分εbx を算出する。図３（ａ）に示すようにｘ成分εbxは次式による。
【数８】

【００４０】
第５のステップとして、xz平面上で非球面面頂1tbxから光軸1oax−1obxに垂線を下ろし、その長さLbxを算出する。図３(a)に示すようにLbxは次式による。
【数９】

【００４１】
上記第４と第５のステップをyz平面にも適用し、yz平面上で非球面面頂1tbyから光軸1oay−1obyに垂線を下ろし、その長さLbyを算出する。図３(b)に示すようにLbyは次式による。
【数１０】

【００４２】
第６のステップとして、光軸1oa−1obに対する非球面軸rbの傾き、即ち非球面偏心量εbを算出する。εbは図３(a)，(b)に示すように次式による。
【数１１】

【００４３】
第７のステップとして、光軸1oa−1obに対する非球面軸rbの偏心方向θbを算出する。θbは光軸に対して非球面面頂が図３(a)，(b)に示すようにｘ方向にLbx、ｙ方向にLbyだけ離れていることより次式による。
【数１２】

【００４４】
上記のステップにより、光軸1oa−1obに対する受け面の反対面1bの非球面偏心量及び方向を正確に求めることができる。
被検レンズ1を被検レンズ受け部3上でレンズの回転位置を変えずに上下を反転させて設置し、同様の検出及び演算を行なえば、上述で求めた面の反対面の非球面偏心量εa及びその方向θaを正確に求めることができる。ただし被検レンズ１を反転しているので、偏心方向については反転させる方向により、ｘ方向もしくはｙ方向の正負が反転し、設計式については、高さ方向が反転する。
【００４５】
（効果Ａ）
このように第１実施形態では、例えばレンズの両面が非球面の場合、近軸偏心測定部5により被検レンズ1の受け面1a及び受け面の反対面1bの近軸曲率中心位置の測定を行なうので、受け面1aが非球面であり、受け面の反対面1bの心出し調整時に受け面1aの近軸曲率中心が回転軸9からずれたとしても、測定値から被検レンズ1光軸を定義し直すことで正確な測定が可能となる。
尚、被検レンズ1を受ける被検レンズ受け部3の受け面も近軸領域である必要がないので、その寸法は加工精度の確保しやすい直径でよい。
また、受け面1aの近軸曲率中心1oaが正確に回転軸9に一致している必要が無いので、被検レンズ受け部3の回転軸9に対する同心度は厳密でなくても高精度の測定が可能となる。
【００４６】
近軸偏心測定部5により上記受け面1aの反対面1bと受け面1aの近軸曲率中心を検出し、非球面軸検出部6によりそのレンズの被検面の非球面の面頂位置を検出しているので、非球面偏心の定義に従った高精度な測定が可能となる。
被検レンズ1を反転させて両面の非球面偏心量を求めた場合でも、評価の基準が近軸曲率中心を結んだ光軸である故に、被検レンズ1を反転させて姿勢が変化しても、両面の近軸曲率中心とレンズとの位置関係は１対１で決定できるので、正確に評価の基準を統一しての高精度測定が可能となる。
また、被検レンズの外径等のその他の部位や、被検レンズ固定用治具等のある基準面を基準として評価を行なう「反転測定評価」と比較しても、最小箇所の測定評価で可能であり、レンズ以外に基準を設けなくてよいという利点がある。
【００４７】
なお、ここまでは、レンズの両面が非球面である被検レンズについて説明してきたが、次に説明するような片面が非球面である場合でも、同様にして非球面偏心量及び方向を求めることができる。
この場合には、図１に例示した構成において、まず被検レンズ1の球面が受け面1a側となるように被検レンズ受け部3に設置する。
【００４８】
片面だけが非球面であるこの被検レンズ1を被検レンズ受け部3にて支持しつつ、回転レンズ支持部材4にて回転させながら受け面1aの反対面1bの近軸曲率がほぼ回転軸9に一致するよう調心を行なうと、被検レンズ1の球面である受け面1aの曲率中心1oaは理論的には常に回転軸9の軸線上となるように調心されるが、受け面1aの面精度や被検レンズ受け部3の被検レンズ1との接触部3bの真円度や回転軸9に対する同軸度の不足により、曲率中心1oaが回転軸9と一致しなくなる場合が生ずる。
【００４９】
被検レンズ1を回転レンズ支持部材4で回転させながら、近軸偏心測定部5を介して受け面の反対面1bの近軸曲率中心1obの回転軸9に対する偏心量を検出し、この偏心量が概略０となるように被検レンズ1の位置調整を行なう。ここでの偏心調整では厳密に近軸曲率中心1obを回転軸9に一致させる必要はないが、受け面1aの曲率中心1oaの偏心量を測定するときに、受け面の反対面1bの偏心量が小さい方が、検出精度が高くなる故にここで行なう。
【００５０】
回転レンズ支持部材4には回転角測定部7が接続されており、その値により被検レンズ1の回転方向の基準を設定し、近軸曲率中心の偏心方向を測定する。
被検レンズ1の受け面の反対面1bの概略心出し調整が完了した後、被検レンズ1の受け面1aの曲率中心1oaを近軸偏心測定部5により先程と同様に回転軸9に対する偏心量と偏心方向を検出する。ただし、この場合においては、受け面の反対面1bを通して受け面1aの曲率中心1oaを観察している故に、近軸偏心測定部5と被検面との間の面の偏心量と方向の影響を考慮しなければならないが、その計算方法については特公昭５１-９６２０号公報にも記載されているように、偏心量を測定する面よりもその前にある面の偏心量が既知であれば、両面の近軸曲率、肉厚、屈折率の被検レンズの設計データを用いて計算可能であり、その方法により受け面1aの偏心量δa及び方向θaを算出可能である。
このように、近軸偏心測定部5と回転角測定部7の出力結果を用いて、受け面1aの曲率中心の偏心量δa、及び偏心方向θa、受け面の反対面1bの近軸曲率中心の偏心量δb及び偏心方向θbを、演算部8によって算出可能である。
【００５１】
図２(d)及び(g)に示すように、近軸曲率中心または曲率中心の偏心量及び偏心方向より被検レンズ1が回転原点位置にあるときの近軸曲率球心位置または曲率中心位置を、ｘｙ平面における値に換算することが可能であり、受け面1aの曲率中心位置は図２(d)に示すように、次式で表わせる。
【数１３】

【００５２】
受け面の反対面1bの近軸曲率中心位置は図２(g)に示すように、次の換算式を用いて演算部8で求める。
【数１４】

【００５３】
つづいて、変位センサ部6を被検レンズ1の被検面1bに応じてその検出軸10の角度を被検面1bの法線に一致させ、変位センサ部6の検出軸10方向の高さも被検レンズ1の被検面1bに応じて調整する。その状態で被検レンズ1を回転レンズ支持部材4により回転させて、検出軸10方向の高さの変化を、回転角測定部7により被検レンズ1の角度変化を出力し、両者を演算部8に入力する。
演算部8では、被検面形状測定部(変位センサ部)6の検出値を回転レンズ支持部材4の回転軸9の方向に変換する。
【００５４】
被検面形状測定部(変位センサ部)6の検出軸10の角度の支点位置と被検レンズ1の位置関係より、図示の測定半径rが算出される。この測定半径rと回転角測定部7の情報と被検面形状測定部(変位センサ部)6の出力を回転軸9方向に分解した情報より、ｘ，ｙ，ｚ座標の三次元座標データに換算する。この測定三次元座標データと被検面1bの設計式を対比させる。この時、被検面形状測定部(変位センサ部)6の検出軸10は、回転軸9に対して傾いた構成となっているので、設計式との比較を行なう為には、回転軸方向の変位への変換を行なう必要がある。
【００５５】
【数１５】

【００５６】
回転軸9からrだけ離れたポイントで非球面軸検出を行なう場合には、(5)式で示される高さ方向の情報を、次式により、ｘ，ｙに分離して設計式と比較を行なう。ここでは、各測定ポイントに対する回転角測定部7の出力をθrotとして表わす。
【００５７】
【数１６】

【００５８】
図１では検出軸10が回転軸9に対して、傾いた構成としているが、この傾きθは０度、即ち回転軸9に対して平行な状態で、被検面形状測定部(変位センサ部)6の検出軸10を構成しても同様な計算が成り立つ。
三次元座標データと設計式とを比較する方法としては、例えば測定三次元データを被検面1bの設計式上でシフト、チルトさせて両者の差が最も小さくなるように行なえばよい。シフト量として(1)，(2)式で与えられる量を代入し、ｘ方向とｙ方向のシフトを固定し、球心位置を中心としてｘ方向とｙ方向にチルトおよびｚ方向にシフトさせて両者の差が最小となる状態を検出する。
【００５９】
測定三次元データのチルト量およびシフト量より逆算すれば回転軸９に対する受け面の反対面１ｂの非球面面頂のｘｙ平面における移動量１ｔｂを求めることができる。図３（ａ）、（ｂ）で示すように、計算で求めたｘ方向のチルト量をＡｂｘ，ｙ方向のチルト量をＡｂｙとすると、非球面面頂のシフト量１tbxおよび１tbyは次式で求められる。
【数１７】

【００６０】
次に、演算部8によって、被検レンズ1の近軸曲率中心位置及び曲率中心位置と被検面1bの面頂位置とにより被検面1bの非球面偏心量εb及びその方向θεbを算出する。
【００６１】
その算出方法について図２(a)〜(g)を用いて説明する。
ここでは、被検レンズ1は受け面の反対面1bのみが非球面であるので、図２(a)，(b)，(c)，(f)に示す受け面1a側の非球面面頂1taは存在しない。
【００６２】
第１のステップとして、受け面１ａの曲率中心位置１oaと受け面の反対面１ｂの近軸曲率中心軸１obを図２（ｄ）及び（ｇ）に示すようにそれぞれｘ、ｙの値に分解する。それぞれの数値は（１）式から（４）式と同様な式にて得られる。
第２のステップとして、近軸曲率中心偏心量と曲率中心偏心量とを考慮して、図２（ａ）におけるｚ軸上での１oaから１obまでの高さＺoを算出する。この高さＺoは次式による。
【数１８】

ここでｒａは受け面１ａの近軸曲率半径、ｒｂは受け面１ｂの近軸曲率半径、ｄはレンズ肉厚を表わす。
【００６３】
第３のステップとして、受け面の反対面1bの面頂シフト量と受け面の偏心量とを考慮して、図２(a)におけるz軸上での1obから1tbまでの高さZbを算出する。この高さzbは次式による。
【数１９】

【００６４】
以降のステップにおいては、xz平面とyz平面に分けて計算を行なうことになる。ここでは一例として先にxz平面上での計算を行ない、その後にyz平面の計算を行なうものとするが、説明の便宜上でそのように行なうのであり、yz平面を先に計算してもよいし、各ステップにおいてxz平面とyz平面を交互に計算を行なってもよい。
【００６５】
第４のステップとして、ｘｚ平面でのｚ軸に対する非球面軸ｒｂｘと光軸１oax−１obxの傾きとから非球面軸偏心のｘ成分εbx を算出する。図３（ａ）に示すようにｘ成分εbxは次式による。
【数２０】

【００６６】
第５のステップとして、xz平面上で非球面面頂1tbxから光軸1oax−1obxに垂線を下ろし、その長さLbxを算出する。図３(a)に示すようにLbxは次式による。
【数２１】

【００６７】
上記第４と第５の各ステップをyz平面にも適用し、yz平面上で非球面面頂1tbyから光軸1oay−1obyに垂線を下ろし、その長さLbyを算出する。図３(b)に示すようにLbyは次式による。
【００６８】
【数２２】

【００６９】
第６のステップとして、光軸1oa−1obに対する非球面軸rbの傾き、即ち非球面偏心量εbを算出する。εbは図３(a)，(b)に示すように次式による。
【数２３】

【００７０】
第７のステップとして、光軸1oa−1obに対する非球面軸rbの偏心方向θbを算出する。θbは光軸に対して非球面面頂が図３(a)，(b)に示すようにｘ方向にLby，ｙ方向にLbyだけ離れていることにより次式による。
【数２４】

【００７１】
（効果Ｂ）
上記のように実施すれば、被検レンズ1が片面非球面であっても、光軸1oa−1obに対する受け面の反対面1bの非球面偏心量及び方向を正確に求めることができる。
【００７２】
以上説明した実施形態は、次のような複数に変形実施してもよく、上記実施形態と同等またはそれ以上の効果も期待できる。
（変形例１）
図５には、その一変形例に係る非球面レンズの偏心測定装置の概略構成を示す。図示の如くに被検面形状測定部(変位センサ部)6を被検レンズ1の上下にそれぞれ設置すれば、反転することなく、受け面1aの非球面軸の傾き量及び方向が検出可能となり、上下面の非球面偏心量が高精度にて測定可能となる。
詳しくは、図５において、非球面レンズの偏心測定装置2は、被検レンズ１を回転自在に保持する被検レンズ受け部3と、被検レンズ受け部3を回転させる為の回転レンズ支持部材4と、回転レンズ支持部材4の回転軸9に対する被検レンズ１の両面1a及び1bの近軸曲率中心の偏心量を検出する為の近軸偏心測定部5と、回転軸9に対するレンズ受け面の反対面1bにおける非球面軸の傾き角を検出する為の被検面形状測定部(変位センサ部)6aと、回転軸9に対するレンズ受け面1aにおける非球面軸の傾き角を検出する為の被検面形状測定部(変位センサ部)6bと、回転軸9の回転角を検出する為の回転角測定部7と、近軸偏心測定部5、被検面形状測定部(変位センサ部)6b及び回転角測定部7の各々の測定値を演算する演算部8と、により構成されている。
【００７３】
つまり変形例１では、被検レンズ１の両面に係わる非球面軸の傾き角をそれぞれ専用に検出する為、被検面形状測定部(変位センサ部)6aおよび被検面形状測定部(変位センサ部)6bの２つで構成し、被検レンズ1の上下にそれぞれ設置している。
【００７４】
なお、被検レンズ受け部3における被検レンズ1との接触部3a、3bは、前述と同様に、回転レンズ支持部材4の回転軸9に対してほぼ同心加工してある。
回転レンズ支持部材4の上面には被検レンズ受け部3が設置されており、レンズ受け部の上端面にある内径側のエッジ3aまたは外径側のエッジ3bにて被検レンズ1を受ける。内径エッジ3a及び外径エッジ3bは回転軸9に対して同心加工してあるので、それぞれのエッジ3a、3bの中心は回転軸9上にある。
【００７５】
なお、10aで示す線は受け面の反対面1bの非球面軸の検出軸、10bで示す線は受け面1aの非球面軸の検出軸、1oaで示す点は被検レンズ1の受け面側の近軸曲率中心、1obで示す点は被検レンズ1の受け面の反対面の近軸曲率中心である。
近軸偏心測定部5は、被検レンズ1の上面にその光学軸を回転レンズ支持部材4の回転軸9と同軸に設置されている。
【００７６】
図５では不図示だが、近軸偏心測定部5の内部には前述同様に、光源と光学系と撮像素子と、光束を光源及び撮像素子の二方向に振り分ける為の光路切替手段とを備えている。光源から照射された光束は光学系により被検レンズ1の被検面の近軸曲率中心に集光するような光束を照射する。近軸偏心測定部5内部の光学系は被検面の曲率に応じて照射する光束の集光点を可変とするように、光学系を構成する一部のレンズ群が移動及び切り替え可能な構成となっている。
【００７７】
近軸偏心測定部5から照射され被検面で反射した光束は同じ光路を戻り、近軸偏心測定部5に入射し、光路内に存在する光路切替手段により折り曲げられて、撮像素子上に結像し、スポット状の像を結ぶ。被検面に全く偏心が無い場合には、被検レンズ1を回転させながら被検面に照射した光束の反射光を撮像素子で観察しても、スポットは振れ回りを生じない。
【００７８】
被検面が回転軸に対して偏心がある場合においては、被検レンズ1を回転しながらその反射光を観察すると、偏心量に応じた半径にてスポットが回転するのを撮像素子にて観察できる。
このスポットの回転半径及び被検レンズの原点状態におけるスポットの回転中心からの方向により、被検面の偏心量及び偏心方向を検出することが可能である。 具体的には、近軸偏心測定部5と回転角測定部7からの信号を演算部8に入力することにより、被検レンズ1を回転させた時の角度変化に対する被検面の近軸曲率中心の近軸偏心測定部5内の撮像素子上の位置変化の測定を行なうことにより、被検面の近軸曲率中心の偏心量及び偏心方向を検出する。
【００７９】
被検面形状測定部(変位センサ部)6a及び6bは、被検レンズ1の回転に伴う被検面1bまたは1aの検出軸10bまたは10a方向の変位量を検出する。図５にはその構成を図示していないが、レーザ光源と干渉光学系とファイバから成り、ファイバ出射端面から被検面に照射された光束は再度ファイバから被検面形状測定部(変位センサ部)6aまたは6bに入射され、変位の変化により干渉縞が変化する、その干渉縞の変化を受光センサで捉え変位量を検出する。
【００８０】
また、回転レンズ支持部材4の回転軸9上に被検面形状測定部(変位センサ部)6a及び6bの回転移動の支点があり、それを中心として被検レンズ1の被検面の測定点の法線に検出軸10aまたは10bを一致するように調整可能であり、支点位置の高さは被検レンズ1に応じて回転軸9上で移動することが可能である。また、被検面形状測定部(変位センサ部)6a及び6bもその検出軸10の方向に高さを被検レンズ1の形状に応じて変更可能である。
【００８１】
被検面形状測定部(変位センサ部)6a及び6bと回転角測定部7からの信号を演算部8に入力することにより、被検レンズ1を回転させたときの角度変化に対する検出軸10a及び10b方向の高さの変化の測定を行なう。
尚、この変形例１においては、両面凸の非球面形状から成る被検レンズ1について説明してあるが、両面または片面が凹の非球面または球面の被検レンズであっても同様に適応可能であることはいうまでもない。
【００８２】
上述のように変形構成された偏心測定装置においては、被検レンズ１を被検レンズ受け部3にて支持しつつ回転レンズ支持部材4にて回転させながら調心を行なうと、被検レンズ1の受け面1aの曲率中心1oaは受け面1aが球面の場合には理論的には常に回転軸9の軸線上となるように調心されるが、受け面1aが非球面の場合には図５に例示のように、レンズ受け部3の内径エッジ3aが受け面1aの面頂から等距離にある場合には近軸曲率中心1oaは回転軸9上にあるが、その関係が成り立たない場合には、近軸曲率中心1oaは回転軸9の軸線上にあるとは限らない。
【００８３】
被検レンズ1を回転レンズ支持部材4で回転させながら、近軸偏心測定部5を介して受け面の反対面1bの近軸曲率中心1obの回転軸9に対する偏心量を検出し、この偏心量が概略０となるように被検レンズ1の位置調整を行なう。ここでの偏心調整では厳密に近軸曲率中心1obを回転軸9に一致させる必要はないが、受け面1aの近軸曲率中心1oaの偏心量を測定するときに受け面の反対面1bの偏心量が小さい方が、検出精度が高くなる故に行なっている。
【００８４】
回転レンズ支持部材4には回転角測定部7が接続されており、その値により被検レンズ1の回転方向の基準を設定し、近軸曲率中心の偏心方向を測定する。
被検レンズ1の受け面の反対面1bの概略心出し調整が完了した後、被検レンズ1の受け面1aの近軸曲率中心1oaを近軸偏心測定部5により先程と同様に回転軸9に対する偏心量と偏心方向を検出する。ただし、この場合においては、受け面の反対面1bを通して受け面1aの近軸曲率中心1oaを観察している故に、近軸偏心測定部5と被検面の間の面の偏心量と方向の影響を考慮しなければならないが、その計算方法については特公昭５１-９６２０号公報にも開示のように、偏心量を測定する面よりも前にある面の偏心量が既知であれば両面の近軸曲率、肉厚、屈折率の被検レンズの設計データを用いて計算可能であり、その方法により受け面1aの偏心量δa及び方向θaを算出可能である。
以上のように、近軸偏心測定部5と回転角測定部7の出力結果を用いて、受け面1a及び受け面の反対面1bの近軸曲率中心の偏心量δa、δb及び偏心方向θa、θbを演算部8により算出可能である。
【００８５】
図２(d)及び図２(g)に示すように、近軸曲率中心の偏心量及び偏心方向より被検レンズ1が回転原点位置にあるときの近軸曲率球心位置をｘｙ平面における値に換算することが可能である。
受け面1aの近軸曲率中心位置は図２(d)に示すように、次式で表わせる。
【数２５】

【００８６】
受け面の反対面1bの近軸曲率中心位置は図２(g)に示すように、次の換算式を用いて演算部8で求める。
【数２６】

【００８７】
次に、変位センサ部6aを被検レンズ1の受け面の反対面1bに応じてその検出軸10の角度を被検面1bの法線に一致させ、変位センサ部6aの検出軸10方向の高さも被検レンズ1の被検面1bに応じて調整する。その状態で被検レンズ1を回転レンズ支持部材4により回転させて、検出軸10a方向の高さの変化を、回転角測定部7により被検レンズ1の角度変化を出力し、両者を演算部8に入力する。
【００８８】
また、同様に変位センサ部6bを被検レンズ1の受け面1aに応じてその検出軸10の角度を被検面1aの法線に一致させ、変位センサ部6の検出軸10方向の高さも被検レンズ1の被検面1aに応じて調整する。その状態で被検レンズ1を回転レンズ支持部材4により回転させて、検出軸10b方向の高さの変化を、回転角測定部7により被検レンズ1の角度変化を出力し、両者を演算部8に入力する。
演算部8では被検面形状測定部(変位センサ部)6a及び6bの検出値を回転レンズ支持部材4の回転軸9の方向に変換する。
【００８９】
被検面形状測定部(変位センサ部)6aの検出軸10aの角度の支点位置と被検レンズ1の形状及び位置関係より、図５に示す測定半径ra’が算出される。このra’と回転角測定部7の情報と被検面形状測定部(変位センサ部)6の出力を回転軸9方向に分解した情報より、ｘ，ｙ，ｚ座標の三次元座標データに換算する。この測定三次元座標データと被検面1bの設計式を対比させる。
この時に被検面形状測定部(変位センサ部)6aの検出軸10aは、回転軸9に対してθaだけ傾いた構成となっているので、設計式との比較を行なう為には、回転軸方向の変位への変換を行なう必要がある。
【００９０】
【数２７】

【００９１】
回転軸9からra’だけ離れたポイントで非球面軸検出を行なう場合には、(5)式で示される高さ方向の情報を、次式により、ｘ，ｙに分離して設計式と比較を行なう。ここでは、各測定ポイントに対する回転角測定部7の出力をθrotとする。
【数２８】

【００９２】
図５では検出軸10aが回転軸9に対して傾いた構成としているが、この傾きθaは０度、即ち回転軸9に対して平行な状態で、被検面形状測定部(変位センサ部)6の検出軸10aを構成しても同様な計算が成り立つ。
三次元座標データと設計式とを比較する方法としては、例えば測定三次元データを被検面1bの設計式上でシフト、チルトさせて両者の差が最も小さくなるように行なえばよい。シフト量として(1)，(2)式で与えられる量を代入し、ｘ方向とｙ方向のシフトを固定し、球心位置を中心としてｘ方向とｙ方向にチルトおよびｚ方向にシフトさせて両者の差が最小となる状態を検出する。
【００９３】
その後、測定三次元データのチルト量およびシフト量より逆算すれば、回転軸９に対する受け面の反対面１ｂの非球面面頂のｘｙ平面における移動量１ｔｂを求めることができる。図４（ａ）、（ｂ）に示すように、上記計算で求めたｘ方向のチルト量をＡｂｘ，ｙ方向のチルト量をＡｂｙとすると、非球面面頂のシフト量１tbxおよび１tbyは次式で求められる。
【数２９】

【００９４】
尚、ここでは説明の都合上、受け面の反対面1bについて述べたが、同様に被検面形状測定部(変位センサ部)6bの出力についても同様の処理を行なえばよい。
【数３０】

【００９５】
回転軸9からrb’だけ離れたポイントで非球面軸検出を行なう場合には、(5)’式で示される高さ方向の情報を、次式により、ｘ，ｙに分離して設計式と比較を行なう。
また、各測定ポイントに対する回転角測定部7の出力をθrotとすと、次式が成り立つ。
【数３１】

【００９６】
受け面の反対面1bと同様に(6)’式で表される三次元データと設計式とを比較してｘ方向とｙ方向のチルト量Aax，Aayを求める。
【００９７】
図６(a)，(b)に示すように非球面の面頂のシフト量1taxおよび1tayは、次式で求められる。
【数３２】

【００９８】
次に、演算部8により被検レンズ1の両面の近軸曲率中心位置と被検面1bの面頂位置とにより被検面1bの非球面偏心量εb及びその方向θεbを算出する。
その算出方法について、図２(a)〜(g)を用いて詳しく説明すると、
第１のステップとして、受け面1aの近軸曲率中心位置1oaと受け面の反対面1bの近軸曲率中心値1obを図２(d)及び(g)に示すようにそれぞれｘ、ｙの値に分解する。 それぞれの数値は(1)式から(4)式と同様な関係式にて得られる。
【００９９】
第２のステップとして、両面の近軸曲率中心偏心量を考慮して、図２（ａ）におけるｚ軸上での１oaから１obまでの高さＺoを算出する。この高さＺoは次式による。
【数３３】

ここでｒａは受け面１ａの近軸曲率半径、ｒｂは受け面１ｂの近軸曲率半径、ｄはレンズ肉厚を表わす。
【０１００】
第３のステップとして、受け面の反対面1bの面頂シフト量と受け面の偏心量とを考慮して、図２(a)におけるz軸上での1obから1tbまでの高さZbを算出する。この高さZbは次式による。
【数３４】

【０１０１】
以降のステップにおいては、xz平面とyz平面に分けて計算を行なうことになる。ここでは一例として先にxz平面上での計算を行ない、その後にyz平面の計算を行なうものとするが、説明の便宜上で上記のように行なうのであり、yz平面を先に計算してもよいし、各ステップにおいてxz平面とyz平面を交互に計算を行なってもよい。
【０１０２】
第４のステップとして、ｘｚ平面でのｚ軸に対する非球面軸ｒｂｘと光軸１oax−１obxの傾きとから非球面軸偏心のｘ成分εbx を算出する。図３（ａ）に示すようにｘ成分εbxは次式による。
【数３５】

【０１０３】
第５のステップとして、xz平面上で非球面面頂1tbxから光軸1oax−1obxに垂線を下ろし、その長さLbxを算出する。図３(a)に示すようにLbxは次式による。
【数３６】

【０１０４】
第４と第５のステップをyz平面にも適用して、yz平面上で非球面面頂1tbyから光軸1oay−1obyに垂線を下ろし、その長さLbyを算出する。図３(b)に示す如くLbyは次式による。
【数３７】

【０１０５】
第６のステップとして、光軸1oa−1obに対する非球面軸rbの傾き、即ち非球面偏心量εbを算出する。εbは図３(a)，(b)に示すように次式による。
【数３８】

【０１０６】
第７のステップとして、光軸1oa−1obに対する非球面軸rbの偏心方向θbを算出する。θbは光軸に対して非球面面頂が図３(a)，(b)に示すようにｘ方向にLbx、ｙ方向にLbyだけ離れていることより、次式で求められる。
【数３９】

【０１０７】
同様に演算部8によって、被検レンズ1の両面の近軸曲率中心位置と受け面1aの面頂位置とにより、受け面1aの非球面偏心量εa及びその方向θεaを算出する。その算出方法を図２(a)〜(g)を用いて説明すると、
第１のステップとして、受け面1aの近軸曲率中心位置1oaと受け面の反対面1bの近軸曲率中心値1obを、図２(d)及び(g)に示すようにそれぞれｘ、ｙの値に分解する。それぞれの数値は(1)式から(4)式と同様な式にて得られる。
【０１０８】
第２のステップとして、両面の近軸曲率中心偏心量を考慮して、図２(a)におけるz軸上での1oaから1obまでの高さZoを算出する。この高さZoは次式による。
【数４０】

【０１０９】
(8)’式の結果は、先に受け面の反対面1bの非球面偏心量を求める時の(8)のZoと同じであるので、省略してよい。
【０１１０】
第３のステップとして、受け面1aの面頂シフト量と受け面1aの偏心量とを考慮して、図２(a)におけるz軸上での1oaから1taまでの高さZaを算出する。この高さＺaは次式による。
【数４１】

【０１１１】
以降のステップにおいては、xz平面とyz平面に分けて計算を行なうことになる。ここでは一例として、先にxz平面上での計算を行ない、その後にyz平面の計算を行なうものとするが、説明の便宜上でそのように行なうのであり、yz平面を先に計算してもよいし、各ステップにおいてxz平面とyz平面を交互に計算を行なってもよい。
【０１１２】
第４のステップとして、xz平面でのｚ軸に対する非球面軸raxと光軸1oax−1obxの傾きとから非球面軸偏心のx成分εaxを算出する。図６(a)に示すようにεaxは次式による。
【数４２】

【０１１３】
第５のステップとして、xz平面上で非球面面頂1taxから光軸1oax−1obxに垂線を下ろし、その長さLaxを算出する。図６(a)に示すようにLaxは次式による。
【数４３】

【０１１４】
第４と第５のステップをyz平面にも適用して、yz平面上で非球面面頂1tayから光軸1oay−1obyに垂線を下ろし、その長さLayを算出する。図６(b)に示すように、Layは次式による。
【数４４】

【０１１５】
第６のステップとして、光軸1oa−1obに対する非球面軸raの傾き、即ち非球面偏心量εaを算出する。Εaは図６(a)，(b)に示すように次式による。
【数４５】

【０１１６】
第７のステップとして、光軸1oa−1obに対する非球面軸raの偏心方向θaを算出する。θaは光軸に対して非球面面頂が図６(a)，(b)に示すようにｘ方向にLay、ｙ方向にLayだけ離れていることより、次式で求められる。
【数４６】

【０１１７】
上記のステップにより、光軸1oa−1obに対する受け面1aの非球面偏心量及び方向を正確に求めることができる。
【０１１８】
このように変形例１によれば、被検面形状測定部(変位センサ部)6aおよび被検面形状測定部(変位センサ部)6bをそれぞれ被検レンズ1の上下に設置しているので、両面に係わる非球面軸の傾き角をそれぞれ専用に検出できるので、その被検レンズを反転することなく上下面それぞれの非球面偏心量が測定可能であり、また、被検レンズを反転する為に測定作業を中断する必要がなくなる。
【０１１９】
（変形例２）
第１実施形態はさらに次のようにも変形実施してよく、その第１実施形態と同等またはそれ以上の効果も期待できる。
図７にはこの変形例に係る非球面レンズの偏心測定装置の概略構成を示す。
この偏心測定装置2は、図示の如く、被検レンズ１を回転自在に保持する被検レンズ受け部3と、鉛直断面で図示された被検レンズ受け部3を回転させる為の回転レンズ支持部材4と、鉛直断面で同様に図示された回転レンズ支持部材4の、回転軸9に対する被検レンズ１の受け面の反対面1bの近軸曲率中心の偏心量を検出する為の近軸偏心測定部5aと、回転レンズ支持部材4の回転軸9に対する被検レンズ１の受け面1aの近軸曲率中心の偏心量を検出する為の近軸偏心測定部5bと、回転軸9に対するレンズ受け面の反対面1bにおける非球面軸の傾き角を検出する為の被検面形状測定部(変位センサ部)6と、回転軸9の回転角を検出する為の回転角測定部7と、上記した近軸偏心測定部5、被検面形状測定部(変位センサ部)6及び回転角測定部7の各々の測定値を演算する演算部8と、により構成されている。
【０１２０】
つまり変形例２では、被検レンズ１の両面に係わる近軸曲率中心の偏心量を検出する為に、近軸偏心測定部5aおよび近軸偏心測定部5bをそれぞれ専用に構成し、被検レンズ1の上下にそれぞれ設置している。
なお、被検レンズ受け部3における被検レンズ1との接触部3a、3bは、前述同様に回転レンズ支持部材4の回転軸9に対してほぼ同心加工されている。この回転レンズ支持部材4もまた、回転軸9に対してほぼ同心加工されている。
【０１２１】
回転レンズ支持部材4の上面には被検レンズ受け部3が設置されており、レンズ受け部の上端面にある内径側のエッジ3aまたは外径側のエッジ3bにて被検レンズ1を受ける。内径エッジ3a及び外径エッジ3bは回転軸9に対して同心加工してあるので、それぞれのエッジ3a、3bの中心は回転軸9上に存在する。
なお、10aで示す軸線は受け面の反対面1bの非球面軸の検出軸、10bで示す軸線は受け面1aの非球面軸の検出軸である。1oaで示す点は被検レンズ1の受け面側の近軸曲率中心、1obで示す点は被検レンズ1の受け面の反対面の近軸曲率中心である。
【０１２２】
近軸偏心測定部5aは被検レンズ1の上面にその光学軸を回転レンズ支持部材4の回転軸9と同軸に設置されていて、同様に近軸偏心測定部5bは被検レンズ1の下面にその光学軸を回転レンズ支持部材4の回転軸9と同軸に設置されている。
鉛直断面で図示された如く回転レンズ支持部材4もまた、近軸偏心測定部5bの測定光束をけらないように、図示の如く回転軸付近の中央部が中空に形成されている。
回転角測定部7は、近軸偏心測定部5bの測定光束をけらないように配置されており、図示していないが、ベルトとプーリにより回転レンズ支持部材4の回転角を回転角測定部7に伝達することにより、回転レンズ支持部材4の回転角を検出する。
【０１２３】
図７には示していないが、近軸偏心測定部5aおよび5bの内部には、光源と光学系と撮像素子と、光束を光源及び撮像素子の二方向に振り分ける為の光路切替手段とを備えている。光源から照射された光束は光学系により被検レンズ1の被検面の近軸曲率中心に集光するような光束を照射する。近軸偏心測定部5a及び5bの内部の光学系は被検面の曲率に応じて照射する光束の集光点を可変とするように、光学系を構成する一部のレンズ群が移動及び切り替え可能な構成となっている。
【０１２４】
近軸偏心測定部5a及び5bから照射されそれぞれの被検面で反射した光束は、同じ光路を戻って近軸偏心測定部5a及び5bに入射し、光路内に存在する光路切替手段により折り曲げられて、撮像素子上に結像し、スポット状の像を結ぶ。被検面に全く偏心が無い場合には、被検レンズ1を回転させながら被検面に照射した光束の反射光を撮像素子で観察しても、スポットは振れ回りを生じない。
【０１２５】
被検面が回転軸に対して偏心がある場合においては、被検レンズ1を回転しながらその反射光を観察すると、偏心量に応じた半径にてスポットが回転するのを撮像素子にて観察できる。
このスポットの回転半径及び被検レンズの原点状態におけるスポットの回転中心からの方向により、被検面の偏心量及び偏心方向を検出することが可能である。
【０１２６】
具体的には、近軸偏心測定部5a及び5bと回転角測定部7からの信号を演算部8に入力することにより、被検レンズ1を回転させた時の角度変化に対する被検面の近軸曲率中心の近軸偏心測定部5a及び5b内の撮像素子上の位置変化の測定を行なうことにより、それぞれの被検面の近軸曲率中心の偏心量及び偏心方向を検出する。被検面形状測定部(変位センサ部)6は、被検レンズ1の回転に伴う被検面1bの検出軸10a方向の変位量を検出する。
【０１２７】
また、図７にはその構成を図示していないが、レーザ光源と干渉光学系とファイバから成り、ファイバ出射端面から被検面に照射された光束は再度ファイバから被検面形状測定部(変位センサ部)6に入射され、変位の変化により干渉縞が変化する、その干渉縞の変化を受光センサで捉え変位量を検出する。
また、回転レンズ支持部材4の回転軸9上に被検面形状測定部(変位センサ部)6の回転移動の支点があり、それを中心として被検レンズ1の被検面の測定点の法線に検出軸10を一致するように調整可能であり、支点位置の高さは被検レンズ1に応じて回転軸9上で移動することが可能である。また、被検面形状測定部(変位センサ部)6もその検出軸10の方向に高さを被検レンズ1の形状に応じて変更可能になっている。
【０１２８】
被検面形状測定部(変位センサ部)6と回転角測定部7からの出力信号を演算部8に入力することにより、被検レンズ1を回転させたときの角度変化に対する検出軸10方向の高さの変化に関する測定を行なえる。
なお、この変形例２においては、両面凸の非球面形状から成る被検レンズ1について説明してあるが、両面または片面が凹の非球面または球面の被検レンズであっても同様に適応可能であることは云うまでもない。
【０１２９】
上述のように変形構成された偏心測定装置において、被検レンズ１を被検レンズ受け部３にて支持しつつ回転レンズ支持部材４にて回転させながら調心を行なうと、被検レンズ１の受け面１ａの曲率中心１ｏａは受け面１ａが球面の場合には理論的には常に回転軸９の軸線上となるように調心されるが、受け面１ａが非球面の場合には図７に示すようにレンズ受け部３の支持点３ｂが受け面１ａの面頂から等距離にある場合には近軸曲率中心１ｏａは回転軸９上にあるが、その関係が成り立たない場合には、近軸曲率中心１ｏａは回転軸９の軸線上にあるとは限らない。
【０１３０】
被検レンズ1を回転レンズ支持部材4で回転させながら、近軸偏心測定部5aを介して受け面の反対面1bの近軸曲率中心1obの回転軸9に対する偏心量を検出し、この偏心量が概略0となるように被検レンズ1の位置調整を行なう。ここでの偏心調整では厳密に近軸曲率中心1obを回転軸9に一致させる必要はないが、受け面1aの近軸曲率中心1oaの偏心量を測定するときに受け面の反対面1bの偏心量が小さい方が検出精度は高くなる故に行なっている。
【０１３１】
回転レンズ支持部材4には回転角測定部7が接続されており、その値により被検レンズ1の回転方向の基準を設定し、近軸曲率中心の偏心方向を測定する。被検レンズ1の受け面の反対面1bの概略心出し調整が完了した後、被検レンズ1の受け面1aの近軸曲率中心1oaを近軸偏心測定部5bにより先程と同様に回転軸9に対する偏心量と偏心方向を検出する。
以上のように、近軸偏心測定部5a及び5bと回転角測定部7の出力結果を用いて、受け面1a及び受け面の反対面1bの近軸曲率中心の偏心量δa、δb及び偏心方向θa、θbを演算部8により算出可能である。
【０１３２】
図２(d)及び(g)に示すように、近軸曲率中心の偏心量及び偏心方向より被検レンズ1が回転原点位置にあるときの近軸曲率球心位置をｘｙ平面における値に換算することが可能である。
受け面1aの近軸曲率中心位置は図２(d)に示すように、次式で表わせる。
【数４７】

【０１３３】
受け面の反対面1bの近軸曲率中心位置は図２(g)に示すように、次の換算式を用いて演算部8で求める。
【数４８】

【０１３４】
次に変位センサ部6を被検レンズ1の受け面の反対面1bに応じてその検出軸10の角度を被検面1bの法線に一致させ、変位センサ部6の検出軸10方向の高さも被検レンズ1の被検面1bに応じて調整する。その状態で被検レンズ1を回転レンズ支持部材4により回転させて、検出軸10a方向の高さの変化を、回転角測定部7により被検レンズ1の角度変化を出力し、両者を演算部8に入力する。
演算部8では被検面形状測定部(変位センサ部)6の検出値を回転レンズ支持部材4の回転軸9の方向に変換する。
【０１３５】
被検面形状測定部(変位センサ部)6の検出軸10の角度の支点位置と被検レンズ1の形状及び位置関係より図７に示す測定半径rが算出される。この測定半径rと回転角測定部7の情報と被検面形状測定部(変位センサ部)6の出力を回転軸9方向に分解した情報より、ｘ，ｙ，ｚ座標の三次元座標データに換算する。この測定三次元座標データと被検面1bの設計式を対比させる。
この時に被検面形状測定部(変位センサ部)6の検出軸10は、回転軸9に対してθa傾いた構成となっているので、設計式との比較を行なう為には、回転軸方向の変位への変換を行なう必要がある。
【０１３６】
【数４９】

【０１３７】
回転軸9からrだけ離れたポイントで非球面軸検出を行なう場合には、(5)式で示される高さ方向の情報を、次式により、ｘ，ｙに分離して設計式と比較を行なう。ここでは、各測定ポイントに対する回転角測定部7の出力をθrotとする。
【数５０】

【０１３８】
図７では検出軸10が回転軸9に対して、傾いた構成としているが、この傾きθは0度、即ち回転軸9に対して平行な状態で、被検面形状測定部(変位センサ部)6の検出軸10を構成しても同様な計算が成り立つ。
三次元座標データと設計式とを比較する方法としては、例えば測定三次元データを被検面1bの設計式上でシフト、チルトさせて両者の差が最も小さくなるように行なえばよい。シフト量として(1)，(2)式で与えられる量を代入し、ｘ方向とｙ方向のシフトを固定し、球心位置を中心としてｘ方向とｙ方向にチルトおよびｚ方向にシフトさせて両者の差が最小となる状態を検出する。
【０１３９】
その後、測定三次元データのチルト量およびシフト量より逆算すれば、回転軸９に対する受け面の反対面１ｂの非球面面頂のｘｙ平面における移動量１ｔｂを求めることができる。図２（ｅ）に示すように移動量１ｔｂのｘ方向の量を１tbx、ｙ方向の量を１tbyとする。また、ｘ方向のチルト量をＡｂｘ、ｙ方向のチルト量をＡｂｙとすると、非球面面頂のシフト量１tbxおよび１tbyは次式で求められる。
【数５１】

【０１４０】
次に演算部8により、被検レンズ1の両面の近軸曲率中心位置と被検面1bの面頂位置とにより被検面1bの非球面偏心量εb及びその方向θεbを算出する。
その演算方法を図２(a)〜(g)を用いて説明すると、
第１のステップとして、受け面1aの近軸曲率中心位置1oaと受け面の反対面1bの近軸曲率中心値1obを図２(d)及び(g)に示すようにそれぞれｘ，ｙの値に分解する。それぞれの数値は(1)式から(4)式と同様な式にて得られる。
【０１４１】
第２のステップとして、両面の近軸曲率中心偏心量を考慮して、図２（ａ）におけるｚ軸上での１oaから１obまでの高さＺoを算出する。この高さＺoは次式による。
【数５２】

ここでｒａは受け面１ａの近軸曲率半径、ｒｂは受け面１ｂの近軸曲率半径、ｄはレンズ肉厚を表わす。
【０１４２】
第３のステップとして、受け面の反対面1bの面頂シフト量と受け面の偏心量とを考慮して、図２(a)におけるz軸上での1obから1tbまでの高さZbを算出する。この高さZbは次式による。
【数５３】

【０１４３】
以降のステップにおいては、ｘｚ平面とｙｚ平面に分けて計算を行なうことになる。ここでは一例として先にｘｚ平面上での計算を行ない、その後にｙｚ平面の計算を行なうものとするが、説明の便宜上でそのように行なうのであり、ｙｚ平面を先に計算しても良いし、各ステップにおいてｘｚ平面とｙｚ平面を交互に計算を行なってもよい。
第４のステップとして、ｘｚ平面でのｚ軸に対する非球面軸ｒｂｘと光軸１oax−１obxの傾きとから非球面軸偏心のｘ成分εbx を算出する。図３（ａ）に示すようにｘ成分εbxは次式による。
【数５４】

【０１４４】
第５のステップとして、xz平面上で非球面面頂1tbxから光軸1oax−1obxに垂線を下ろし、その長さLbxを算出する。図３(a)に示すようにLbxは次式による。
【数５５】

【０１４５】
第４と第５のステップをyz平面にも適用し、yz平面上で非球面面頂1tbyから光軸1oay−1obyに垂線を下ろし、その長さLbyを算出する。図３(b)に示すようにLbyは次式による。
【数５６】

【０１４６】
第６のステップとして、光軸1oa−1obに対する非球面軸rbの傾き、即ち非球面偏心量εbを算出する。εbは図３(a)，(b)に示すように次式による。
【数５７】

【０１４７】
第７のステップとして、光軸1oa−1obに対する非球面軸rbの偏心方向θbを算出する。θbは光軸に対して非球面面頂が、図３(a)，(b)に示すようにｘ方向にLbx、ｙ方向にLbyだけ離れていることより、次式で求められる。
【数５８】

【０１４８】
上記のステップにより、光軸1oa−1obに対する受け面の反対面1bの非球面偏心量及び方向を正確に求めることができる。
被検レンズ1を被検レンズ受け部3上で上下を反転させて設置し、同様の検出及び演算を行なえば上記で求めた面の反対面の非球面偏心量εa及びその方向θaを正確に求めることができる。
【０１４９】
このように変形例２によれば、被検レンズ1の上下に近軸偏心測定部5aおよび近軸偏心測定部5bをそれぞれ専用に設置しているので、測定用の光線を被検レンズ１の受け面1aの反対面1bを透過させずに、その受け面1aの近軸曲率中心の偏心量と方向を検出できるので、高精度に近軸曲率中心を求めることが可能となり、非球面偏心量が高精度に測定可能となる。
このほかにも、本発明の要旨を逸脱しない範囲で種々の変形実施が可能である。
【０１５０】
以上、実施形態とその変形例に基づき説明したが、本明細書中には次の発明が含まれている。
（１） 前記被検レンズは、両面が非球面の場合のみならず、両面または片面が非球面または球面である場合であっても、同様に測定可能であることを特徴とする、請求項１に記載の偏心測定装置を提供できる。
（２） 前記被検レンズは、両面が凸形状の非球面のみならず、両面または片面が凹形状の非球面または球面であっても、同様に測定可能であることを特徴とする、請求項１に記載の偏心測定装置を提供できる。
【０１５１】
【発明の効果】
以上説明したように、本発明によれば、容易にかつ高精度に非球面レンズの非球面偏心量及びその方向の測定方法及び測定装置を提供することが可能となる。
【図面の簡単な説明】
【図１】 本発明の第１実施形態として非球面レンズの偏心測定装置の構成を概略的に示す構成図。
【図２】 図２(a)〜(g)は非球面偏心値を求める際の考え方を示し、
(a)は、レンズ両面の近軸曲率中心と非球面面頂をｘ,ｙ,ｚの三次元で示す説明図、
(b)は、レンズ両面の近軸曲率中心と非球面面頂をｘｚ平面で示す説明図、
(c)は、レンズ両面の近軸曲率中心と非球面面頂をｙｚ平面で示す説明図、
(d)は、受け面の近軸曲率中心の位置をｘｙ平面で示す説明図、
(e)は、受け面の反対面の非球面面頂の位置をｘｙ平面で示す説明図、
(f)は、受け面の非球面面頂の位置をｘｙ平面で示す説明図、
(g)は、受け面の反対面の近軸曲率中心の位置をｘｙ平面で示す説明図。
【図３】 図３(a)，(b)は、非球面偏心値を求める際の考え方を図解する説明図。
【図４】 非球面レンズの偏心測定方法に関係する演算の手順を示す流れ図。
【図５】 第１実施形態の変形例として非球面レンズの偏心測定装置の構成を概略的に示す構成図。
【図６】 図６(a)，(b)は、非球面の面頂のシフト量1taxおよび1tayを示す説明図。
【図７】 第１実施形態のもう１つの変形例として非球面レンズの偏心測定装置の構成を概略的に示す構成図。
【図８】 図８(a)〜(e)は非球面をもった非球面レンズを示し、
(a)は、両面が非球面の場合の二つの非球面軸と光軸とのずれを示す説明図、
(b)は、片面のみ非球面の場合の非球面軸と光軸とのずれを示す説明図、
(c)〜(e)は、非球面偏心の方向(原点から非球面面頂への方向)を表わすグラフ。
【図９】 従来の非球面レンズの偏心測定装置を示す概略構成図。
【符号の説明】
1…被検レンズ（測定対象非球面レンズ）、
1a，1b…被検面（測定対象レンズ面：受け面、反対面）、
1oa，1ob…近軸曲率中心、
1ta，1tb…面頂、
2…偏心測定装置、
3…被検レンズ受け部、
3a,3b…接触部（内径、外径エッジ）、
4…回転レンズ支持部材、
5，5a，5b…近軸偏心測定部、
6，6a，6b…変位センサ部（被検面形状測定部）、
7…回転角測定部、
8…演算部（ＣＰＵ：各種プログラムを含む）、
9…回転軸、
10…検出軸。
Ｓ１０〜Ｓ４０…偏心測定の演算手順。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aspheric lens eccentricity measuring apparatus and an eccentricity measuring method thereof for measuring the inclination of an aspherical axis of an aspherical lens including both a double-sided aspherical lens and a single-sided aspherical lens.
[0002]
[Prior art]
As a measurement technique for inspecting the eccentricity of an aspheric lens, in recent years, for example, Japanese Patent Application Laid-Open No. 7-159283 discloses an eccentricity measuring device for the aspherical lens and an eccentricity measuring method thereof. This conventional aspheric lens eccentricity measuring method will be described with reference to FIGS. 8A to 8E, and an outline of a conventional aspheric lens eccentricity measuring apparatus for realizing this will be described with reference to FIG.
First, FIG. 8A illustrates a lens having aspheric surfaces on both sides. Both aspherical surfaces 1b and 1a indicated by solid lines of this aspherical lens as a test lens are surfaces designed with reference to the paraxial spherical surfaces indicated by virtual lines 1a ′ and 1b ′. A line h connecting the centers of curvature 1ob and 1oa of the paraxial spherical surfaces 1a ′ and 1b ′ becomes the optical axis of the aspherical lens 1. Further, in a lens having both aspheric surfaces as illustrated, the vertex of the aspherical surface 1a together with the aspherical axis ib connecting the vertex (surface top) 1tb of the aspherical surface 1b and the center of curvature 1ob of the paraxial spherical surface 1b ′ ( There are two aspherical axes, that is, an aspherical axis ia connecting the surface top) 1ta and the center of curvature 1oa of the paraxial spherical surface 1a ′. If this aspherical lens is manufactured as designed, these three axes will coincide perfectly, but in practice it is difficult to manufacture such a lens.
[0003]
In the state where the two aspherical axes ia and ib and the optical axis h are shifted as shown in FIG. 8A, the aspherical surfaces 1b and 1a are inclined from the ideal state, and the optical axis h and the aspherical axes ia and ib are They intersect at angles εa and εb, respectively. This angle εb is the aspheric eccentricity of the aspherical surface 1b, and the angle εa is the aspherical eccentricity of the aspherical surface 1a. Then, as shown in the graphs of FIGS. 8 (c) and 8 (d), the direction from the origin to the aspheric surface apex (aspheric apex) is the direction of aspheric decentering with respect to the optical axis (ie, the receiving surface). The direction of the aspherical eccentricity of the surface 1a is θεa, and the direction of the aspherical eccentricity of the surface 1b opposite to the receiving surface is θεb). When an aspherical lens is manufactured, in order to evaluate the completed lens, it is necessary to first measure the amount and direction of the aspherical eccentricity, and then perform product evaluation and mold correction.
[0004]
On the other hand, FIG. 8B illustrates an aspheric lens when only one surface is aspheric. The aspheric surface 1b is a surface designed on the basis of the paraxial spherical surface indicated by the virtual line 1b ′. A line h connecting the paraxial center of curvature 1ob of the aspherical surface 1b and the center of curvature 1oa of the spherical surface 1a is the optical axis of the aspherical lens 1. In the case of such an aspherical lens, one aspherical axis ib connecting the vertex 1tb of the aspherical surface 1b and the center of curvature 1ob of the paraxial spherical surface 1b ′ is defined. If this aspherical lens is manufactured as designed, the optical axis h and the aspherical axis ib completely coincide with each other, but it is actually difficult to manufacture such a lens. As shown in FIG. 8B, the aspherical surface 1b is inclined from the ideal state, and the optical axis h and the aspherical axis ib intersect at an angle εb. This angle εb is the amount of aspherical eccentricity of the aspherical surface 1b, and the direction from the origin to the top of the aspherical surface is the direction of the aspherical surface eccentricity θεb with reference to the optical axis as shown in the graph of FIG. 8 (e). . Therefore, when only one surface is aspheric, it is necessary to perform lens evaluation and mold correction based on the aspheric eccentricity εb and the direction θεb.
[0005]
FIG. 9 discloses an eccentricity measuring apparatus 100 for an aspheric lens described in Japanese Patent Laid-Open No. 7-159283. The decentration measuring apparatus 100 includes a means 102 for holding a test lens 101 having both aspheric surfaces, a driving means 103 for rotating the holding means 102 about a rotation axis substantially overlapping the optical axis of the test lens, Means 104 for detecting the rotation origin position of the test lens, a light source 105 for irradiating the test lens with light from the rotation axis direction, and an optical system for forming a spot image of the light reflected from the test lens 107, means 108 for detecting the position of the spot image provided at the imaging position of the optical system, two displacement measuring means 109, 110 for measuring the displacement in the optical axis direction of both surfaces of the lens to be tested, and the spot image It is characterized by comprising a position detection means 108, a rotation origin position detection means 104, and a calculation means 112 that receives data from the displacement measurement means 109 and 110 and calculates the eccentric direction and the amount of eccentricity of the aspherical axis. Further, it is suggested that it is desirable to provide an actuator 111 that moves the lens to be measured in a direction substantially orthogonal to the optical axis k in accordance with an instruction from the calculation means 112.
[0006]
Further, the above-described conventional technique teaches that aspherical eccentricity measurement is performed by the following first, second, and third conventional measurement methods. That is, in the first conventional measuring method, the holding means 102 has a hollow cylindrical holding portion having an axis substantially parallel to the rotation axis k, and the diameter of the cylinder can be regarded as the substantially spherical surface of the aspheric lens. Implemented as a configuration that is not larger than the diameter of the paraxial region, or a configuration in which the hollow cylindrical holding portion is formed of a thin-walled cylinder, or a contact edge with the test lens 101 having a knife edge shape. It was done.
In the first conventional measurement method, the test lens 101 that is both aspheric on both sides is held by the receiving surface 101a, and the test lens 101 is rotated about the aspherical axis of the receiving surface 101a. Then, the test lens is irradiated with light from the direction of the rotation axis, and reflected light from the opposite surface 101b of the receiving surface of the test lens 101 is formed as a spot image on the imaging surface of the optical system, and the spot image The eccentric direction and the amount of eccentricity between the aspherical axis of the receiving surface 101a and the lens optical axis are obtained from the position of the lens and the size of the circle drawn by the spot image when the test lens 101 rotates. The displacement in the rotation axis direction of the opposite surface 101b of the receiving surface is used as a calculated value, and the displacement in the rotation axis direction of the opposite surface 101b of the receiving surface is measured. Then, the calculated value is subtracted from the actual measurement value to obtain an eccentric amount and an eccentric direction of the aspherical axis with respect to the lens optical axis with respect to the opposite surface 101b of the receiving surface.
[0007]
As a second conventional measurement method, the displacement of the test lens 101 in the direction of the rotation axis accompanying the rotation of the receiving surface 101a is measured, and the test lens 101 is substantially orthogonal to the rotation axis so that this displacement becomes zero. A configuration in which the aspherical axis of the receiving surface 101a coincides with the rotation axis by moving in the direction, or an actuator 111 for moving the lens 101 to be measured in a direction substantially perpendicular to the rotation axis k is provided. This suggests that the displacement of the receiving surface 101a may be configured such that the actuator 111 is feedback-driven according to the amount of displacement.
Further, as a third conventional measurement method, the test lens 101 that is both aspheric on both sides is held by the receiving surface 101a, and the test lens is centered on an axis passing through the paraxial center of curvature of the opposite surface 101b of the receiving surface. Rotate 101. The lens 101 is irradiated with light from the direction of the rotation axis, and the reflected light from the receiving surface 101a of the lens 101 is imaged as a spot image on the imaging surface of the optical system. A method of obtaining an eccentric direction and an amount of eccentricity between the rotation axis and the optical axis k of the test lens 101 from the position of the spot image and the size of a circle drawn by the spot image when the test lens 101 rotates. Or from the amount of eccentricity between the rotation axis and the optical axis of the test lens 101, the displacement in the rotation axis direction of both surfaces of the test lens 101 based on the decentration is calculated, and the rotation axes of both surfaces of the test lens 101 It also suggests a method and a configuration in which the amount of eccentricity and the direction of eccentricity of the two aspherical axes with respect to the lens optical axis are obtained by actually measuring the displacement in the direction and subtracting the calculated value from the obtained actual measurement values.
With such a conventional technique, it is possible to measure the amount of eccentricity and the direction of eccentricity of the aspherical surface of the aspheric lens with respect to the optical axis.
[0008]
[Problems to be solved by the invention]
However, in the above-described prior art, it is difficult to perform measurement with high accuracy for the following reason. That is, in the first conventional measurement method, when receiving the aspherical surface of the test lens, the diameter of the portion to be held is reduced, and the test lens is tilted by receiving the surface in the paraxial region. Although it is premised that the center of curvature does not shift, it is not clear to what extent the difference between the paraxial spherical surface and the aspherical surface can be regarded as the paraxial region. Actually, by tilting the lens to be examined, the center of curvature may deviate from the rotation axis, and as the deviation increases, the error in the aspherical axis eccentricity measurement result increases.
Also, in order to reduce the deviation of the center of curvature that occurs when the test lens is tilted, it is necessary to perform processing with high accuracy according to the accuracy with which the roundness of the surface that receives the test lens is to be measured. However, the accuracy becomes more difficult as the diameter of the portion that receives the lens to be examined becomes smaller.
[0009]
In the second conventional measurement method, the displacement in the direction of the rotation axis accompanying the rotation of the receiving surface is measured, and the lens to be measured is moved in a direction substantially perpendicular to the rotation axis so that this displacement becomes zero. The aspherical axis and the rotation axis are made to coincide. Matching in this way is a very difficult task in the actual case because the amount of displacement does not become zero due to the influence of measurement system noise, unevenness of the test surface, etc. It is. Here, it is possible to consider that the aspherical axis and the rotation axis coincide with each other by performing processing that considers a predetermined displacement amount or less to be 0, but if the amount is increased, the adjustment becomes simple, but measurement The error increases. On the other hand, if the amount is reduced, the measurement error is reduced, but adjustment becomes difficult.
Further, in the third conventional measurement method, the test lens 101 is rotated about an axis passing through the paraxial curvature center of the opposite surface 101b of the receiving surface, and a spot image of the reflected light from the receiving surface 101a is drawn. The direction of eccentricity and the amount of eccentricity between the rotation axis and the optical axis k of the lens 101 to be examined are obtained from However, although not explicitly stated, in this case as well, an operation is required in which the paraxial curvature center of the surface 101b opposite to the receiving surface of the lens to be tested is completely aligned with the rotation axis. However, it is very difficult to make them completely coincide with each other due to the influence of the resolution of the paraxial curvature center measurement system, the resolution of the adjustment system, etc., and the difference remains at about 0.5 μm. It is also possible to consider that the paraxial center of curvature coincides with the rotation axis by performing processing that considers a predetermined amount or less of the circle drawn by the spot image as 0. However, if the amount is set large, the adjustment becomes simple, but the measurement error becomes large. Conversely, if the amount is small, the measurement error becomes small, but the adjustment becomes difficult. In the above-described conventional method, the adjustment residual is handled ignoring, so that an error occurs in the calculation of the paraxial curvature center position on the receiving surface side, which causes a reduction in measurement accuracy.
[0010]
As described above, in the conventional measurement method, the measurement is started with the assumption that the aspherical axis of the aspherical lens as the test lens and the rotation axis coincide with each other on the assumption and assumption of the installation state. Met. Further, when determining the amount of eccentricity and the direction of eccentricity of the aspherical axis with respect to the lens optical axis, which is caused by the fact that the optical axis h as an aspherical lens and the aspherical axis ib of the aspherical lens do not completely coincide with each other. The calculation of the top position (calculation based on the calculation of tilt amount and shift amount) for the aspheric lens is not performed, and reconfirmation of the deviation of the axis (aspheric axis) that should pass through the top is required. It was not done. Therefore, no appropriate adjustment is made, and as a result, there is a limit to the improvement in measurement accuracy.
[0011]
Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to easily and accurately measure the aspheric eccentricity and direction of an aspheric lens and its method. It is to provide a measuring device for this purpose.
[0012]
[Means for Solving the Problems]
In order to solve the above problems and achieve the object, the present invention takes the following measures. That is, according to the first aspect, the lens receiving portion for holding the lens to be examined, the rotating lens support member configured to rotate the lens receiving portion, and the target to the rotation axis of the rotating lens support member. A paraxial decentering measuring means for detecting the amount and direction of decentering of the paraxial curvature center on both sides of the test lens, a test surface shape measuring means for detecting the shape of the test surface, and rotation of the test lens The rotation angle measuring means for detecting the angle, the data obtained by rotating the test lens and measuring with the test surface shape measuring means and the design formula of the test surface are compared, and the difference between the two is The smallest relative shift amount and tilt amount are obtained, the position of the surface apex with respect to the rotation axis is calculated from the shift amount and tilt amount, and the position of the surface apex and the object measured by the paraxial eccentricity measuring means are calculated. From the decentering amount and direction of the paraxial curvature center on both sides of the test lens, Proposes a calculating means for calculating a tilt amount and direction of the aspherical surface axis with respect to the optical axis of the lens, the eccentricity measuring apparatus of the aspherical lens having the.
[0013]
According to the second aspect, the paraxial decentering measuring means for detecting the decentering amount of the paraxial curvature center of both surfaces of the test lens, and the test surface shape measuring means for detecting the shape of the test surface of the test lens. And an aspherical lens eccentricity measuring method in an eccentricity measuring device comprising a rotational angle measuring means for detecting the rotational angle of the subject lens, wherein the paraxial eccentricity measuring means is used to measure both sides of the subject lens relative to the rotational axis. A paraxial curvature center detecting step for detecting an eccentric amount and direction of a paraxial curvature center; and Test surface shape The shape measurement step of measuring the shape of the test surface by the measuring means, the measured test surface shape and a predetermined design formula are compared, and the top position of the test surface shape with the smallest difference between them is calculated. A first calculation step, and a second calculation step for determining the eccentricity of the aspherical lens from the decentering amount and direction of the paraxial center of curvature of both surfaces of the lens to be tested and the position of the top of the surface. We propose a method for measuring the eccentricity of aspherical lenses.
The aspheric lens referred to here includes both a double-sided aspherical lens and a single-sided aspherical lens.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described and described with reference to FIGS.
(First embodiment)
FIG. 1 shows an aspheric lens decentration measuring apparatus according to a first embodiment of the present invention, and FIGS. 2 and 3 illustrate in detail the concept of obtaining an aspheric decentration value. FIG. 4 is a flowchart showing a calculation procedure related to the method of measuring the eccentricity of the aspheric lens. In FIG. 1, an aspherical lens decentration measuring device 2 includes a test lens receiving portion 3 that rotatably holds a test lens 1 to be measured, and a rotating lens support member for rotating the test lens receiving portion 3. 4, a paraxial eccentricity measuring unit 5 for detecting the eccentricity of the paraxial curvature centers of the test surfaces 1 a and 1 b on both surfaces of the test lens 1 with respect to the rotational axis 9 of the rotating lens support member 4, and a rotational axis 9 for detecting the inclination angle of the aspherical axis on the opposite surface 1b of the lens receiving surface with respect to 9 (displacement sensor unit) 6 and the rotation angle measuring unit for detecting the rotation angle of the rotating shaft 9 7, a paraxial eccentricity measuring unit 5, a surface shape measuring unit (displacement sensor unit) 6, and a calculation unit 8 for calculating the measured values of the rotation angle measuring unit 7.
[0015]
The test lens 1 placed on the test lens receiving portion 3 shown here in the vertical cross section and the contact portions (inner diameter, outer diameter edge) 3a, 3b serving as the receiving portions are rotated by the rotating lens support member 4. Almost concentric with the shaft 9. A test lens receiving portion 3 is installed on the upper surface of the rotating lens support member 4, and the test is performed at the inner diameter side inner edge 3a or the outer diameter side outer diameter edge 3b on the upper end surface of the test lens receiving portion 3. Lens 1 is received. Since the inner diameter edge 3 a and the outer diameter edge 3 b are processed concentrically with respect to the rotating shaft 9, the centers of the edges 3 a and 3 b of the inner and outer diameters are on the rotating shaft 9.
[0016]
Here, the lens 1 to be measured is an aspheric lens having aspheric surfaces on both sides. The line indicated by 10 is the detection axis of the aspherical axis, the point indicated by 1oa is the center of paraxial curvature on the receiving surface side of the lens 1 to be tested, and the point indicated by 1ob is near the surface opposite to the receiving surface of the lens 1 to be tested. It is the axial curvature center.
In addition, the paraxial eccentricity measuring unit 5 is installed on the upper surface of the lens 1 to be tested so that its optical axis is coaxial with the rotational axis 9 of the rotating lens support member 4.
[0017]
Although not shown in detail in FIG. 1, the paraxial eccentricity measuring unit 5 includes a light source, an optical system, and an image sensor, and further, a light beam along the optical axis is transmitted in two directions of the light source and the image sensor. An optical path switching means comprising a mirror or a prism for distributing the light to the light is provided. A light beam emitted from a light source such as a lamp irradiates a light beam that is condensed at the center of the paraxial curvature of the test surface of the test lens 1 by the optical system. The optical system provided in the paraxial decentering measurement unit 5 configures the optical system so that the condensing point of the light beam to be irradiated can be changed according to the curvature of the test surface of the test lens 1. Some lens groups can be moved and switched.
[0018]
The light beam irradiated from the paraxial decentering measurement unit 5 and reflected by the test surface returns to the same optical path, enters the paraxial decentering measurement unit 5, is bent by the optical path switching means existing in the optical path, and is connected to the image sensor. And connect spot-like images. If the test surface is not decentered at all (that is, the ideal form of design), the spot will not appear even if the reflected light of the light beam irradiated on the test surface 1 is observed with the image sensor while rotating the test lens 1. Does not cause “swing”.
Actually, when the test surface is decentered with respect to the rotation axis, when the reflected light is observed while the test lens 1 is rotated, the spot rotates as a “swing” with a radius corresponding to the amount of eccentricity. Can be observed with the image sensor in the paraxial eccentricity measuring unit 5.
Therefore, the amount of eccentricity and the direction of eccentricity of the test surface can be detected from the radius of the spot and the direction from the center of rotation of the spot in the origin state of the test lens.
[0019]
Specifically, by inputting output signals from the paraxial eccentricity measurement unit 5 and the rotation angle measurement unit 7 to the calculation unit 8, the paraxiality of the test surface with respect to the angle change when the test lens 1 is rotated By measuring the change in position of the center of curvature on the image sensor, the amount of eccentricity and the direction of eccentricity of the paraxial center of curvature of the test surface can be calculated and detected (see: S10 in FIG. 4).
The test surface shape measurement unit (displacement sensor unit) 6 detects the amount of displacement in the direction of the detection axis 10 of the opposite surface 1b of the receiving surface accompanying the rotation of the test lens 1. Although the detailed configuration is not shown in FIG. 1, the light source is composed of a laser light source, an interference optical system, and a fiber. The interference fringes change due to the change in displacement. The change of the interference fringe is caught by the light receiving sensor, and the displacement amount is detected.
[0020]
Further, there is a fulcrum for rotational movement of the test surface shape measurement unit (displacement sensor unit) 6 on the rotation axis 9 of the rotary lens support member 4, and the measurement of the surface 1b opposite to the receiving surface of the test lens 1 is centered on this fulcrum The detection axis 10 can be adjusted so as to coincide with the normal of the point, and the height of the fulcrum position can be moved on the rotation axis 9 in accordance with the lens 1 to be examined. In addition, the surface shape measuring unit (displacement sensor unit) 6 itself can change the height in the direction of the detection axis 10 according to the lens 1 to be tested.
By inputting output signals from the test surface shape measurement unit (displacement sensor unit) 6 and the rotation angle measurement unit 7 to the calculation unit 8, the detection axis 10 direction relative to the angle change when the test lens 1 is rotated is measured. Can measure height change.
In the first embodiment of the present invention, the lens 1 to be tested has a convex aspherical shape on both surfaces of the lens. However, the lens has a concavely aspherical or spherical surface on either side or one side. Needless to say, even a lens can be similarly applied.
[0021]
More specifically, a method for measuring the eccentricity of the aspheric lens described above will be described. In the eccentricity measuring apparatus having the above-described configuration, alignment is performed while rotating the rotating lens support member 4 while supporting the lens 1 to be tested by the lens receiving portion 3 to be tested. When the receiving surface 1a is a spherical surface, the center of curvature 1oa of the receiving surface 1a of the lens 1 to be examined is theoretically always aligned on the axis of the rotating shaft 9. However, when the receiving surface 1a is aspherical, the paraxial curvature center 1oa rotates when the inner diameter edge 3a of the lens receiving portion 3 is equidistant from the top of the receiving surface 1a, as illustrated in FIG. If the relationship exists on the axis 9 but the relationship does not hold, the paraxial center of curvature 1oa does not exist on the axis of the rotating shaft 9.
[0022]
Therefore, while rotating the test lens 1 with the rotating lens support member 4, the amount of eccentricity with respect to the rotational axis 9 of the paraxial center of curvature 1ob of the opposite surface 1b of the receiving surface is detected via the paraxial eccentricity measuring unit 5. The position adjustment (eccentricity adjustment) of the test lens 1 is performed so that the amount of eccentricity becomes approximately zero. In the eccentricity adjustment here, it is not necessary to make the paraxial curvature center 1ob exactly coincide with the rotation axis 9, but the calculation is performed in the paraxial region when measuring the eccentricity of the paraxial curvature center 1oa of the receiving surface 1a. The detection accuracy is higher when the eccentricity of the opposite surface 1b of the receiving surface 1a is smaller. A rotation angle measuring unit 7 is connected to the rotating lens support member 4, and a reference for the rotation direction of the lens 1 to be measured is set based on the measured rotation angle value, and the eccentric direction of the paraxial curvature center is measured.
[0023]
After completing the `` rough centering adjustment '' of the surface 1b opposite to the receiving surface of the lens 1 to be tested, the paraxial center of curvature 1oa of the receiving surface 1a of the lens 1 to be tested is measured by the paraxial eccentricity measuring unit 5 in the same manner as before. The amount of eccentricity and the direction of eccentricity with respect to the rotating shaft 9 are detected. However, in this case, since the paraxial curvature center 1oa of the receiving surface 1a is observed through the opposite surface 1b of the receiving surface, the amount of eccentricity and direction of the surface between the paraxial eccentricity measuring unit 5 and the test surface It must be calculated taking into account the impact. As for the calculation method, as disclosed in Japanese Patent Publication No. 51-9620, if the amount of eccentricity of the surface ahead of the surface for measuring the amount of eccentricity is known, the paraxial curvature and thickness of both surfaces are known. The design data of the test lens such as the refractive index can be calculated, and the eccentric amount Δa and the direction θa of the receiving surface 1a can be calculated by this calculation method.
As described above, by using the output results of the paraxial eccentricity measuring unit 5 and the rotation angle measuring unit 7, the arithmetic unit 8 causes the eccentric amounts δa and δb of the paraxial curvature centers of the receiving surface 1a and the opposite surface 1b of the receiving surface to be calculated. And the eccentric directions θa and θb can be calculated (details will be described later).
[0024]
Next, a method for obtaining an aspheric eccentric value will be described with reference to FIGS. 2A shows the positions of the above-mentioned paraxial curvature centers 1oa, 1ob on both sides and the aspherical surface apexes 1ta, 1tb in a three-dimensional relationship of xyz, and FIGS. 2B, 2C show xz. 2 (d) and (g) show the positions of the paraxial curvature centers 1oa and 1ob in the xy plane, and FIGS. 2 (e) and 2 (f) show the aspherical surface tops 1tb and 1ta, respectively. Is shown on the xy plane.
[0025]
As shown in FIGS. 2 (d) and 2 (g), the paraxial curvature sphere center position when the lens 1 to be tested is at the rotation origin position from the decentering amount and decentering direction of the paraxial curvature centers 1oa and 1ob is expressed in the xy plane. It is possible to convert to a value at. That is,
The position of the paraxial center of curvature 1oa of the receiving surface 1a can be expressed by the following equation as shown in FIG.
[0026]
[Expression 1]

[0027]
The paraxial curvature center position of the opposite surface 1b of the receiving surface 1a is as shown in FIG.
[Expression 2]

The calculation unit 8 uses the conversion formula
[0028]
Subsequently, the angle of the detection axis 10 of the displacement sensor unit 6 is matched with the normal line of the test surface 1b according to the test surface 1b of the test lens 1, and the height of the displacement sensor unit 6 in the direction of the detection axis 10 is also set. Adjust according to the test surface 1b of the test lens 1. In this state, the test lens 1 is rotated by the rotating lens support member 4, the height change in the direction of the detection axis 10 is output, and the angle change of the test lens 1 is output by the rotation angle measurement unit 7, and both are calculated. Type in 8.
The calculation unit 8 converts the detection value of the surface shape measurement unit (displacement sensor unit) 6 into the direction of the rotation axis 9 of the rotating lens support member 4.
[0029]
A measurement radius r shown in FIG. 1 is calculated from the positional relationship between the fulcrum position of the angle of the detection axis 10 of the test surface shape measurement unit (displacement sensor unit) 6 and the test lens 1. From this measurement radius r and information of the rotation angle measurement unit 7 and information obtained by decomposing the output of the test surface shape measurement unit (displacement sensor unit) 6 in the direction of the rotation axis 9, the three-dimensional coordinate data of the x, y and z coordinates is obtained. Convert. The three-dimensional coordinate data based on the output signal of the measurement unit is compared with the design formula (design formula) of the test surface 1b (see: S20 in FIG. 4).
At this time, since the detection shaft 10 of the surface shape measurement unit (displacement sensor unit) 6 is inclined with respect to the rotation shaft 9, in order to compare with the design formula, It is necessary to convert to displacement.
[0030]
[Equation 3]

[0031]
When aspherical axis detection is performed at a point separated from the rotation axis 9 by r, the information in the height direction shown in equation (5) is separated into x and y by the following equation and compared with the design equation. Do. Here, the output of the rotation angle measurement unit 7 for each measurement point is θrot.
[Expression 4]

[0032]
FIG. 1 illustrates the case where the detection axis 10 is tilted with respect to the rotation axis 9, but this inclination θ is 0 degrees, that is, in a state parallel to the rotation axis 9. Even if the detection axis 10 of the (displacement sensor unit) 6 is configured, the same calculation as described above is established.
[0033]
As a specific method for comparing the above-described 3D coordinate data with the design formula, for example, the measurement 3D data is shifted or tilted on the design formula of the test surface 1b so that the difference between the two is minimized. Adjustments can be made. That is, as the shift amount, the amounts given by the equations (1) and (2) are substituted for x and y, respectively, the shift in the x direction and the y direction is fixed, and the tilt in the x direction and the y direction is centered on the spherical center position. And a shift in the z direction to detect a state in which the difference between the two is minimized.
[0034]
Thereafter, by calculating backward from the tilt amount and the shift amount of the measured three-dimensional data, the amount of movement 1tb in the xy plane of the aspheric surface top of the opposite surface 1b of the receiving surface with respect to the rotating shaft 9 can be obtained (see: FIG. 4). S30).
The tilt amount and the shift amount will be described with reference to FIGS. 3A and 3B. As illustrated in FIGS. 3A and 3B, the tilt amount in the x direction obtained by the above calculation is calculated. Assuming that the amount of tilt in the Abx, y direction is Aby, the shift amounts 1tbx and 1tby of the aspheric surface top are obtained by the following equations.
[Equation 5]

[0035]
Further, the calculation unit 8 calculates the aspheric eccentricity εb and the direction θεb of the test surface 1b based on the data of the paraxial curvature center positions of both surfaces of the test lens 1 and the top position of the test surface 1b ( Reference: S40 in FIG.
This calculation method will be described in detail with reference to FIGS. 2 (a) to 2 (g).
As a first step, the paraxial curvature center position 1oa of the receiving surface 1a and the paraxial curvature center value 1ob of the opposite surface 1b of the receiving surface are respectively set to x and y as shown in FIGS. 2 (d) and (g). Break down into values. Each numerical value is obtained by a formula similar to formulas (1) to (4).
[0036]
As a second step, the height Zo from 1 oa to 1 ob on the z-axis in FIG. 2A is calculated in consideration of the amount of eccentricity of the paraxial curvature of both surfaces. This height Zo is according to the following equation.
[Formula 6]

Here, ra represents the paraxial radius of curvature of the receiving surface 1a, rb represents the paraxial radius of curvature of the receiving surface 1b, and d represents the lens thickness.
[0037]
As a third step, the height Zb from 1ob to 1tb on the z-axis in Fig. 2 (a) is calculated in consideration of the top shift amount of the opposite surface 1b of the receiving surface and the eccentric amount of the receiving surface. To do. The height Zb is calculated by the following formula.
[Expression 7]

[0038]
In the subsequent steps, calculations are performed separately for the xz plane and the yz plane. Here, as an example, the calculation on the xz plane is performed first, and then the calculation on the yz plane is performed. However, for convenience of explanation, the calculation may be performed first, and the yz plane may be calculated first. In each step, calculation may be performed alternately on the xz plane and the yz plane.
[0039]
As a fourth step, the x component εbx of the aspherical axis eccentricity is calculated from the aspherical axis rbx with respect to the z axis in the xz plane and the inclination of the optical axis 1oax-1obx. As shown in FIG. 3A, the x component εbx is expressed by the following equation.
[Equation 8]

[0040]
As a fifth step, a perpendicular line is drawn from the aspherical surface top 1tbx to the optical axis 1oax-1obx on the xz plane, and the length Lbx is calculated. As shown in FIG. 3 (a), Lbx is according to the following equation.
[Equation 9]

[0041]
The above fourth and fifth steps are also applied to the yz plane, and a perpendicular line is drawn from the aspheric surface top 1tby to the optical axis 1oay-1oby on the yz plane, and the length Lby is calculated. As shown in FIG. 3 (b), Lby is according to the following equation.
[Expression 10]

[0042]
As a sixth step, the inclination of the aspheric axis rb relative to the optical axis 1oa-1ob, that is, the aspheric eccentricity εb is calculated. As shown in FIGS. 3 (a) and 3 (b), εb is obtained by the following equation.
[Expression 11]

[0043]
As a seventh step, the eccentric direction θb of the aspherical axis rb with respect to the optical axis 1oa-1ob is calculated. θb is given by the following equation because the aspherical surface top is separated from the optical axis by Lbx in the x direction and Lby in the y direction as shown in FIGS. 3 (a) and 3 (b).
[Expression 12]

[0044]
By the above steps, the aspheric eccentricity and direction of the surface 1b opposite to the receiving surface with respect to the optical axis 1oa-1ob can be accurately obtained.
If the test lens 1 is placed upside down on the test lens receiving part 3 without changing the rotational position of the lens, and the same detection and calculation are performed, the aspherical eccentricity of the surface opposite to the surface obtained above is obtained. The quantity εa and its direction θa can be determined accurately. However, since the lens 1 to be examined is inverted, the positive or negative direction in the x direction or the y direction is inverted depending on the direction in which the eccentric direction is inverted, and the height direction is inverted in the design formula.
[0045]
(Effect A)
As described above, in the first embodiment, for example, when both surfaces of the lens are aspherical surfaces, the paraxial eccentricity measurement unit 5 measures the paraxial curvature center positions of the receiving surface 1a of the lens 1 to be tested and the opposite surface 1b of the receiving surface. Even if the paraxial center of curvature of the receiving surface 1a deviates from the rotation axis 9 when adjusting the centering of the opposite surface 1b of the receiving surface, the measured lens 1 optical axis is measured. By redefining, accurate measurement becomes possible.
Since the receiving surface of the lens receiving portion 3 that receives the lens 1 does not need to be a paraxial region, the dimension thereof may be a diameter that facilitates ensuring processing accuracy.
In addition, since it is not necessary that the paraxial center of curvature 1oa of the receiving surface 1a exactly coincides with the rotation axis 9, high-precision measurement is possible even if the concentricity of the lens receiving portion 3 with respect to the rotation axis 9 is not strict. Is possible.
[0046]
The paraxial eccentricity measuring unit 5 detects the opposite surface 1b of the receiving surface 1a and the center of the paraxial curvature of the receiving surface 1a, and the aspherical axis detecting unit 6 detects the aspherical surface top position of the test surface of the lens. Therefore, highly accurate measurement according to the definition of aspheric eccentricity is possible.
Even when the test lens 1 is inverted and the aspheric decentering amount on both sides is obtained, the posture is changed by inverting the test lens 1 because the evaluation standard is the optical axis connecting the paraxial center of curvature. However, since the positional relationship between the paraxial center of curvature on both surfaces and the lens can be determined on a one-to-one basis, it is possible to perform high-accuracy measurement by accurately unifying evaluation criteria.
In addition, compared with “reverse measurement evaluation” in which evaluation is performed based on a reference surface such as the outer diameter of the lens to be examined and a reference surface such as a jig for fixing the lens to be examined, the measurement evaluation of the smallest part is possible. There is an advantage that a reference other than the lens need not be provided.
[0047]
Up to this point, the lens to be tested has been described as having both aspherical surfaces. However, even when one side as described below is an aspherical surface, the amount of aspherical eccentricity and the direction are determined in the same manner. Can do.
In this case, in the configuration illustrated in FIG. 1, first, the test lens 1 is installed in the test lens receiving portion 3 so that the spherical surface of the test lens 1 is on the receiving surface 1a side.
[0048]
While the test lens 1 having only one aspheric surface is supported by the test lens receiving portion 3, the paraxial curvature of the opposite surface 1b of the receiving surface 1a is substantially the rotation axis while being rotated by the rotating lens support member 4. If the alignment is made to match 9, the center of curvature 1oa of the receiving surface 1a, which is the spherical surface of the lens 1 to be examined, is theoretically always aligned to be on the axis of the rotating shaft 9, but the receiving surface The curvature center 1oa may not coincide with the rotation axis 9 due to the surface accuracy of 1a, the roundness of the contact portion 3b of the lens receiving portion 3 with the lens 1 to be tested, or the lack of coaxiality with the rotation shaft 9. .
[0049]
While rotating the test lens 1 with the rotating lens support member 4, the amount of eccentricity with respect to the rotation axis 9 of the paraxial center of curvature 1ob of the opposite surface 1b of the receiving surface is detected via the paraxial eccentricity measuring unit 5. The position of the test lens 1 is adjusted so that is approximately 0. In the eccentricity adjustment here, it is not necessary to make the paraxial center of curvature 1ob exactly coincide with the rotation axis 9, but when measuring the amount of eccentricity of the center of curvature 1oa of the receiving surface 1a, the amount of eccentricity of the opposite surface 1b of the receiving surface This is performed here because the detection accuracy is higher when the value is smaller.
[0050]
A rotation angle measuring unit 7 is connected to the rotating lens support member 4, and a reference is set for the rotation direction of the lens 1 to be measured, and the eccentric direction of the paraxial curvature center is measured.
After the rough centering adjustment of the opposite surface 1b of the receiving surface of the test lens 1 is completed, the center of curvature 1oa of the receiving surface 1a of the test lens 1 is decentered with respect to the rotating shaft 9 by the paraxial eccentricity measuring unit 5 as before. Detect quantity and eccentric direction. However, in this case, since the center of curvature 1oa of the receiving surface 1a is observed through the opposite surface 1b of the receiving surface, the influence of the amount and direction of the surface eccentricity between the paraxial eccentricity measuring unit 5 and the test surface However, as described in Japanese Patent Publication No. 51-9620, the calculation method is known if the eccentricity of the surface preceding the surface on which the eccentricity is measured is known. Further, it is possible to calculate using the design data of the test lens of the paraxial curvature, thickness, and refractive index of both surfaces, and the eccentric amount Δa and direction θa of the receiving surface 1a can be calculated by the method.
Thus, using the output results of the paraxial eccentricity measuring unit 5 and the rotation angle measuring unit 7, the eccentric amount δa of the center of curvature of the receiving surface 1a, the eccentric direction θa, and the paraxial center of curvature of the opposite surface 1b of the receiving surface The calculation unit 8 can calculate the eccentric amount Δb and the eccentric direction θb.
[0051]
As shown in FIGS. 2 (d) and 2 (g), the paraxial curvature sphere center position or the curvature center position when the lens 1 to be tested is at the rotation origin position from the decentering amount and decentering direction of the paraxial curvature center or curvature center. Can be converted into a value on the xy plane, and the center of curvature of the receiving surface 1a can be expressed by the following equation as shown in FIG.
[Formula 13]

[0052]
The paraxial curvature center position of the opposite surface 1b of the receiving surface is obtained by the calculation unit 8 using the following conversion formula as shown in FIG.
[Expression 14]

[0053]
Subsequently, the angle of the detection axis 10 of the displacement sensor unit 6 is matched with the normal line of the test surface 1b according to the test surface 1b of the test lens 1, and the height of the displacement sensor unit 6 in the direction of the detection axis 10 is also set. Adjust according to the test surface 1b of the test lens 1. In this state, the test lens 1 is rotated by the rotating lens support member 4, the height change in the direction of the detection axis 10 is output, and the angle change of the test lens 1 is output by the rotation angle measurement unit 7, and both are calculated. Type in 8.
The calculation unit 8 converts the detection value of the surface shape measurement unit (displacement sensor unit) 6 into the direction of the rotation axis 9 of the rotating lens support member 4.
[0054]
The illustrated measurement radius r is calculated from the position relationship between the fulcrum position of the angle of the detection axis 10 of the test surface shape measurement unit (displacement sensor unit) 6 and the test lens 1. From this measurement radius r and information of the rotation angle measurement unit 7 and information obtained by decomposing the output of the test surface shape measurement unit (displacement sensor unit) 6 in the direction of the rotation axis 9, the three-dimensional coordinate data of the x, y and z coordinates is obtained. Convert. The measured three-dimensional coordinate data is compared with the design formula of the test surface 1b. At this time, since the detection shaft 10 of the surface shape measuring unit (displacement sensor unit) 6 is inclined with respect to the rotation shaft 9, in order to compare with the design formula, the direction of the rotation axis Needs to be converted to displacement.
[0055]
[Expression 15]

[0056]
When aspherical axis detection is performed at a point separated from the rotation axis 9 by r, the information in the height direction shown in equation (5) is separated into x and y by the following equation and compared with the design equation. Do. Here, the output of the rotation angle measurement unit 7 for each measurement point is represented as θrot.
[0057]
[Expression 16]

[0058]
In FIG. 1, the detection axis 10 is inclined with respect to the rotation axis 9, but this inclination θ is 0 degree, that is, in a state parallel to the rotation axis 9, the surface shape measuring unit (displacement sensor unit) The same calculation is true even if the detection axis 10 of 6) is configured.
As a method of comparing the three-dimensional coordinate data with the design formula, for example, the measurement three-dimensional data may be shifted and tilted on the design formula of the surface 1b to be measured so that the difference between the two is minimized. Substituting the amount given by equations (1) and (2) as the shift amount, fixing the shift in the x and y directions, and shifting in the tilt and z directions in the x and y directions around the center of the ball A state where the difference between the two is minimized is detected.
[0059]
By calculating backward from the tilt amount and shift amount of the measured three-dimensional data, the amount of movement 1tb in the xy plane of the aspheric surface top of the opposite surface 1b of the receiving surface with respect to the rotating shaft 9 can be obtained. As shown in FIGS. 3A and 3B, assuming that the calculated tilt amount in the x direction is Abx and the tilt amount in the y direction is Aby, the shift amounts 1tbx and 1tby of the aspheric surface top are expressed by the following equations. Desired.
[Expression 17]

[0060]
Next, the calculation unit 8 calculates the aspherical eccentricity εb and the direction θεb of the test surface 1b from the paraxial curvature center position and the curvature center position of the test lens 1 and the surface top position of the test surface 1b. .
[0061]
The calculation method will be described with reference to FIGS.
Here, since only the surface 1b opposite the receiving surface of the lens 1 to be tested is an aspherical surface, the aspherical surface apex on the receiving surface 1a side shown in FIGS. 2 (a), (b), (c), and (f). 1ta does not exist.
[0062]
As a first step, the center of curvature 1oa of the receiving surface 1a and the paraxial center of curvature 1ob of the opposite surface 1b of the receiving surface are decomposed into values x and y, respectively, as shown in FIGS. 2 (d) and 2 (g). To do. Each numerical value is obtained by the same formula as formulas (1) to (4).
As a second step, the height Zo from 1 oa to 1ob on the z-axis in FIG. 2A is calculated in consideration of the paraxial curvature center eccentricity and the curvature center eccentricity. This height Zo is according to the following equation.
[Expression 18]

Here, ra represents the paraxial radius of curvature of the receiving surface 1a, rb represents the paraxial radius of curvature of the receiving surface 1b, and d represents the lens thickness.
[0063]
As a third step, the height Zb from 1ob to 1tb on the z-axis in Fig. 2 (a) is calculated in consideration of the top shift amount of the opposite surface 1b of the receiving surface and the eccentric amount of the receiving surface. To do. This height zb is according to the following equation.
[Equation 19]

[0064]
In the subsequent steps, calculations are performed separately for the xz plane and the yz plane. Here, as an example, the calculation on the xz plane is performed first, and then the calculation on the yz plane is performed. However, this is done for convenience of explanation, and the yz plane may be calculated first. In each step, the xz plane and the yz plane may be calculated alternately.
[0065]
As a fourth step, the x component εbx of the aspherical axis eccentricity is calculated from the aspherical axis rbx with respect to the z axis in the xz plane and the inclination of the optical axis 1oax-1obx. As shown in FIG. 3A, the x component εbx is expressed by the following equation.
[Expression 20]

[0066]
As a fifth step, a perpendicular line is drawn from the aspherical surface top 1tbx to the optical axis 1oax-1obx on the xz plane, and the length Lbx is calculated. As shown in FIG. 3 (a), Lbx is according to the following equation.
[Expression 21]

[0067]
The above fourth and fifth steps are also applied to the yz plane, a perpendicular line is drawn from the aspheric surface top 1tby to the optical axis 1oay-1oby on the yz plane, and the length Lby is calculated. As shown in FIG. 3 (b), Lby is according to the following equation.
[0068]
[Expression 22]

[0069]
As a sixth step, the inclination of the aspherical axis rb with respect to the optical axis 1oa-1ob, that is, the aspherical eccentricity εb is calculated. εb is obtained by the following equation as shown in FIGS.
[Expression 23]

[0070]
As a seventh step, the eccentric direction θb of the aspherical axis rb with respect to the optical axis 1oa-1ob is calculated. θb is given by the following equation because the aspherical surface top is separated from the optical axis by Lby in the x direction and Lby in the y direction as shown in FIGS. 3 (a) and 3 (b).
[Expression 24]

[0071]
(Effect B)
If implemented as described above, even if the subject lens 1 is a single-sided aspherical surface, the aspherical eccentricity and direction of the surface 1b opposite to the receiving surface with respect to the optical axis 1oa-1ob can be accurately obtained.
[0072]
The embodiment described above may be modified into a plurality of modifications as described below, and an effect equal to or greater than that of the above embodiment can be expected.
(Modification 1)
FIG. 5 shows a schematic configuration of an aspheric lens decentration measuring apparatus according to a modification thereof. As shown in the figure, if the test surface shape measurement unit (displacement sensor unit) 6 is installed above and below the test lens 1, the tilt amount and direction of the aspherical axis of the receiving surface 1a can be detected without inversion. In addition, the aspheric eccentricity of the upper and lower surfaces can be measured with high accuracy.
Specifically, in FIG. 5, an aspherical lens decentration measuring apparatus 2 includes a test lens receiving portion 3 that rotatably holds the test lens 1 and a rotating lens support member for rotating the test lens receiving portion 3. 4, a paraxial eccentricity measuring unit 5 for detecting the eccentricity of the paraxial curvature center of both surfaces 1 a and 1 b of the test lens 1 with respect to the rotating shaft 9 of the rotating lens support member 4, and a lens receiving surface for the rotating shaft 9 For detecting the inclination angle of the aspherical axis on the lens receiving surface 1a with respect to the rotating shaft 9 and the surface shape measuring part (displacement sensor part) 6a for detecting the inclination angle of the aspherical axis on the opposite surface 1b Test surface shape measurement unit (displacement sensor unit) 6b, rotation angle measurement unit 7 for detecting the rotation angle of the rotary shaft 9, paraxial eccentricity measurement unit 5, test surface shape measurement unit (displacement sensor unit) 6b and a calculation unit 8 that calculates the measurement values of the rotation angle measurement unit 7.
[0073]
That is, in the first modification, since the inclination angles of the aspherical axes related to both surfaces of the lens 1 to be tested are detected exclusively, the surface shape measuring unit (displacement sensor unit) 6a and the surface shape measuring unit (displacement sensor) are detected. Part) 6b, which are respectively installed above and below the lens 1 to be examined.
[0074]
Note that the contact portions 3a and 3b of the test lens receiving portion 3 with the test lens 1 are substantially concentrically processed with respect to the rotation shaft 9 of the rotary lens support member 4 as described above.
A test lens receiving portion 3 is installed on the upper surface of the rotating lens support member 4, and receives the test lens 1 at an inner diameter side edge 3a or an outer diameter side edge 3b on the upper end surface of the lens receiving portion. Since the inner diameter edge 3a and the outer diameter edge 3b are processed concentrically with respect to the rotating shaft 9, the centers of the respective edges 3a and 3b are on the rotating shaft 9.
[0075]
The line indicated by 10a is the detection axis of the aspherical axis of the opposite surface 1b of the receiving surface, the line indicated by 10b is the detection axis of the aspherical axis of the receiving surface 1a, and the point indicated by 1oa is the receiving surface side of the lens 1 to be tested The point indicated by 1ob is the paraxial curvature center of the surface opposite to the receiving surface of the lens 1 to be tested.
The paraxial decentering measuring unit 5 is installed on the upper surface of the lens 1 to be tested so that its optical axis is coaxial with the rotating shaft 9 of the rotating lens support member 4.
[0076]
FIG. Although not shown, the paraxial eccentricity measuring unit 5 includes a light source, an optical system, an image sensor, and an optical path switching unit for distributing a light beam in two directions, the light source and the image sensor, as described above. The light beam emitted from the light source irradiates a light beam that is condensed at the paraxial curvature center of the test surface of the test lens 1 by the optical system. The optical system inside the paraxial decentering measurement unit 5 is configured so that a part of the lens group constituting the optical system can be moved and switched so that the condensing point of the light beam to be irradiated can be changed according to the curvature of the test surface. It has become.
[0077]
The light beam irradiated from the paraxial eccentricity measuring unit 5 and reflected by the surface to be tested returns to the same optical path, enters the paraxial eccentricity measuring unit 5, is bent by the optical path switching means existing in the optical path, and is connected to the image sensor. And connect spot-like images. In the case where the test surface is not decentered at all, even if the reflected light of the light beam applied to the test surface is observed with the image sensor while rotating the test lens 1, the spot does not sway.
[0078]
When the test surface is decentered with respect to the rotation axis, when the reflected light is observed while rotating the test lens 1, the image sensor observes that the spot rotates with a radius corresponding to the amount of eccentricity. it can.
The amount of eccentricity and the direction of eccentricity of the surface to be detected can be detected from the rotation radius of the spot and the direction from the rotation center of the spot in the origin state of the lens to be detected. Specifically, by inputting signals from the paraxial eccentricity measurement unit 5 and the rotation angle measurement unit 7 to the calculation unit 8, the paraxial curvature of the test surface with respect to the angle change when the test lens 1 is rotated. By measuring the position change on the image sensor in the central paraxial eccentricity measuring unit 5, the eccentric amount and the eccentric direction of the paraxial curvature center of the surface to be measured are detected.
[0079]
The test surface shape measuring units (displacement sensor units) 6a and 6b detect the amount of displacement of the test surface 1b or 1a in the direction of the detection axis 10b or 10a as the test lens 1 rotates. Although the configuration is not shown in FIG. 5, the light source is composed of a laser light source, an interference optical system, and a fiber, and the light beam irradiated onto the test surface from the fiber exit end face is again sent from the fiber to the test surface shape measuring unit (displacement sensor unit). ) The incident light enters 6a or 6b, and the interference fringe changes due to the change in displacement. The change in the interference fringe is detected by the light receiving sensor, and the displacement amount is detected.
[0080]
In addition, there are fulcrums for rotational movement of the test surface shape measurement units (displacement sensor units) 6a and 6b on the rotation axis 9 of the rotary lens support member 4, and the measurement points of the test surface of the test lens 1 centering on this fulcrum The detection axis 10a or 10b can be adjusted to coincide with the normal line, and the height of the fulcrum position can be moved on the rotation axis 9 according to the lens 1 to be examined. Further, the heights of the test surface shape measuring units (displacement sensor units) 6a and 6b can be changed in the direction of the detection axis 10 according to the shape of the test lens 1.
[0081]
By inputting the signals from the test surface shape measurement units (displacement sensor units) 6a and 6b and the rotation angle measurement unit 7 to the calculation unit 8, the detection shaft 10a and the detection shaft 10a with respect to the angle change when the test lens 1 is rotated Measure the change in height in the 10b direction.
In the first modification, the test lens 1 having a double-sided convex aspherical shape is described. However, the present invention can be similarly applied to a test lens having a double-sided or one-sided concave aspherical or spherical surface. Needless to say.
[0082]
In the eccentricity measuring apparatus modified as described above, when the test lens 1 is centered while being rotated by the rotating lens support member 4 while being supported by the test lens receiving portion 3, the test lens 1 The center of curvature 1oa of the receiving surface 1a is theoretically always aligned to be on the axis of the rotating shaft 9 when the receiving surface 1a is spherical, but when the receiving surface 1a is aspheric, FIG. In the case where the inner diameter edge 3a of the lens receiving portion 3 is equidistant from the top of the receiving surface 1a, the paraxial curvature center 1oa is on the rotation axis 9, as shown in the example, but the relationship does not hold. The paraxial center of curvature 1oa is not necessarily on the axis of the rotating shaft 9.
[0083]
While rotating the test lens 1 with the rotating lens support member 4, the amount of eccentricity with respect to the rotation axis 9 of the paraxial center of curvature 1ob of the opposite surface 1b of the receiving surface is detected via the paraxial eccentricity measuring unit 5. The position of the test lens 1 is adjusted so that is approximately 0. The eccentricity adjustment here does not require the paraxial center of curvature 1ob to exactly coincide with the rotation axis 9, but when measuring the amount of eccentricity of the paraxial center of curvature 1oa of the receiving surface 1a, the eccentricity of the opposite surface 1b of the receiving surface This is done because the smaller the amount, the higher the detection accuracy.
[0084]
A rotation angle measuring unit 7 is connected to the rotating lens support member 4, and a reference is set for the rotation direction of the lens 1 to be measured, and the eccentric direction of the paraxial curvature center is measured.
After the rough centering adjustment of the surface 1b opposite to the receiving surface of the test lens 1 is completed, the paraxial center of curvature 1oa of the receiving surface 1a of the test lens 1 is rotated by the paraxial eccentricity measuring unit 5 in the same manner as before. The amount of eccentricity and the direction of eccentricity are detected. However, in this case, since the paraxial curvature center 1oa of the receiving surface 1a is observed through the opposite surface 1b of the receiving surface, the amount of eccentricity and direction of the surface between the paraxial eccentricity measuring unit 5 and the test surface Although the influence must be taken into consideration, as disclosed in Japanese Examined Patent Publication No. 51-9620, the calculation method of both sides is known if the amount of eccentricity of the surface before the surface where the amount of eccentricity is measured is known. The calculation can be made using the design data of the lens to be examined having the paraxial curvature, the thickness, and the refractive index, and the eccentric amount Δa and the direction θa of the receiving surface 1a can be calculated by the method.
As described above, using the output results of the paraxial eccentricity measuring unit 5 and the rotation angle measuring unit 7, the eccentric amounts δa and δb and the eccentric direction θa of the paraxial curvature center of the receiving surface 1a and the opposite surface 1b of the receiving surface, θb can be calculated by the calculation unit 8.
[0085]
As shown in FIGS. 2 (d) and 2 (g), the paraxial curvature sphere center position when the test lens 1 is at the rotation origin position from the decentering amount and decentering direction of the paraxial curvature center is a value in the xy plane. Can be converted to
The paraxial curvature center position of the receiving surface 1a can be expressed by the following equation as shown in FIG.
[Expression 25]

[0086]
The paraxial curvature center position of the opposite surface 1b of the receiving surface is obtained by the calculation unit 8 using the following conversion formula as shown in FIG.
[Equation 26]

[0087]
Next, in accordance with the surface 1b opposite to the receiving surface of the lens 1 to be detected, the displacement sensor unit 6a is matched with the normal of the surface 1b to be detected in the direction of the detection axis 10 of the displacement sensor unit 6a. The height is also adjusted according to the test surface 1b of the test lens 1. In this state, the test lens 1 is rotated by the rotating lens support member 4, the change in height in the direction of the detection axis 10a is output, and the change in the angle of the test lens 1 is output by the rotation angle measurement unit 7. Type in 8.
[0088]
Similarly, the angle of the detection axis 10 of the displacement sensor unit 6b is matched with the normal line of the test surface 1a according to the receiving surface 1a of the test lens 1, and the height of the displacement sensor unit 6 in the direction of the detection axis 10 is also set. Adjustment is made according to the test surface 1a of the test lens 1. In this state, the test lens 1 is rotated by the rotating lens support member 4, the change in height in the direction of the detection axis 10b is output, and the change in the angle of the test lens 1 is output by the rotation angle measuring unit 7, and both are calculated. Type in 8.
The calculation unit 8 converts the detected values of the surface shape measuring units (displacement sensor units) 6a and 6b into the direction of the rotation axis 9 of the rotating lens support member 4.
[0089]
The measurement radius ra ′ shown in FIG. 5 is calculated from the fulcrum position of the angle of the detection axis 10a of the test surface shape measurement unit (displacement sensor unit) 6a and the shape and positional relationship of the test lens 1. From this ra 'and the information of the rotation angle measuring unit 7 and the information obtained by disassembling the output of the surface shape measuring unit (displacement sensor unit) 6 in the direction of the rotation axis 9, it is converted into three-dimensional coordinate data of x, y, z coordinates. To do. The measured three-dimensional coordinate data is compared with the design formula of the test surface 1b.
At this time, the detection axis 10a of the surface shape measuring unit (displacement sensor unit) 6a is configured to be inclined by θa with respect to the rotation axis 9, so in order to compare with the design formula, the rotation axis Conversion to directional displacement is required.
[0090]
[Expression 27]

[0091]
When detecting the aspherical axis at a point ra 'away from the rotation axis 9, the information in the height direction shown in equation (5) is separated into x and y by the following equation and compared with the design equation To do. Here, the output of the rotation angle measurement unit 7 for each measurement point is θrot.
[Expression 28]

[0092]
In FIG. 5, the detection axis 10a is inclined with respect to the rotation axis 9, but this inclination θa is 0 degree, that is, in a state parallel to the rotation axis 9, the surface shape measurement unit (displacement sensor unit). The same calculation holds true even if six detection axes 10a are configured.
As a method of comparing the three-dimensional coordinate data with the design formula, for example, the measurement three-dimensional data may be shifted and tilted on the design formula of the surface 1b to be measured so that the difference between the two is minimized. Substituting the amount given by equations (1) and (2) as the shift amount, fixing the shift in the x and y directions, and shifting in the tilt and z directions in the x and y directions around the center of the ball A state where the difference between the two is minimized is detected.
[0093]
Thereafter, by calculating backward from the tilt amount and the shift amount of the measured three-dimensional data, the amount of movement 1tb in the xy plane of the aspheric surface top of the opposite surface 1b of the receiving surface with respect to the rotating shaft 9 can be obtained. As shown in FIGS. 4A and 4B, when the tilt amount in the x direction obtained by the above calculation is Abx and the tilt amount in the y direction is Aby, the shift amounts 1tbx and 1tby of the aspheric surface top are expressed by the following equations. Is required.
[Expression 29]

[0094]
Here, for convenience of explanation, the opposite surface 1b of the receiving surface has been described. Similarly, the same processing may be performed for the output of the test surface shape measurement unit (displacement sensor unit) 6b.
[30]

[0095]
When aspherical axis detection is performed at a point separated by rb ′ from the rotation axis 9, the information in the height direction shown by the equation (5) ′ is separated into x and y by the following equation and the design equation: Make a comparison.
Further, when the output of the rotation angle measurement unit 7 for each measurement point is θrot, the following equation is established.
[31]

[0096]
Similar to the opposite surface 1b of the receiving surface, the three-dimensional data represented by the equation (6) ′ is compared with the design equation to determine the tilt amounts Aax and Aay in the x and y directions.
[0097]
As shown in FIGS. 6 (a) and 6 (b), the shift amounts 1tax and 1tay of the aspheric surface top are obtained by the following equations.
[Expression 32]

[0098]
Next, the calculation unit 8 calculates the aspheric eccentricity εb and the direction θεb of the test surface 1b based on the paraxial curvature center positions of both surfaces of the test lens 1 and the surface top position of the test surface 1b.
The calculation method will be described in detail with reference to FIGS. 2 (a) to 2 (g).
As a first step, the paraxial curvature center position 1oa of the receiving surface 1a and the paraxial curvature center value 1ob of the opposite surface 1b of the receiving surface are the values of x and y, respectively, as shown in FIGS. 2 (d) and 2 (g). Disassembled into Each numerical value can be obtained by the same relational expression as Expressions (1) to (4).
[0099]
As a second step, the height Zo from 1 oa to 1 ob on the z-axis in FIG. 2A is calculated in consideration of the amount of eccentricity of the paraxial curvature of both surfaces. This height Zo is according to the following equation.
[Expression 33]

Here, ra represents the paraxial radius of curvature of the receiving surface 1a, rb represents the paraxial radius of curvature of the receiving surface 1b, and d represents the lens thickness.
[0100]
As a third step, the height Zb from 1ob to 1tb on the z-axis in Fig. 2 (a) is calculated in consideration of the top shift amount of the opposite surface 1b of the receiving surface and the eccentric amount of the receiving surface. To do. This height Zb is according to the following equation.
[Expression 34]

[0101]
In the subsequent steps, calculations are performed separately for the xz plane and the yz plane. Here, as an example, the calculation on the xz plane is performed first, and then the calculation on the yz plane is performed. However, for convenience of explanation, it is performed as described above, and the yz plane may be calculated first. In each step, calculation may be performed alternately on the xz plane and the yz plane.
[0102]
As a fourth step, the x component εbx of the aspherical axis eccentricity is calculated from the aspherical axis rbx with respect to the z axis in the xz plane and the inclination of the optical axis 1oax-1obx. As shown in FIG. 3A, the x component εbx is expressed by the following equation.
[Expression 35]

[0103]
As a fifth step, a perpendicular line is drawn from the aspherical surface top 1tbx to the optical axis 1oax-1obx on the xz plane, and the length Lbx is calculated. As shown in FIG. 3 (a), Lbx is according to the following equation.
[Expression 36]

[0104]
The fourth and fifth steps are also applied to the yz plane, a perpendicular line is drawn from the aspheric surface top 1tby to the optical axis 1oay-1oby on the yz plane, and the length Lby is calculated. As shown in FIG. 3 (b), Lby is according to the following equation.
[Expression 37]

[0105]
As a sixth step, the inclination of the aspherical axis rb with respect to the optical axis 1oa-1ob, that is, the aspherical eccentricity εb is calculated. εb is obtained by the following equation as shown in FIGS.
[Formula 38]

[0106]
As a seventh step, the eccentric direction θb of the aspherical axis rb with respect to the optical axis 1oa-1ob is calculated. θb can be obtained by the following equation because the aspherical surface top is separated from the optical axis by Lbx in the x direction and Lby in the y direction as shown in FIGS. 3 (a) and 3 (b).
[39]

[0107]
Similarly, the calculation unit 8 calculates the aspheric eccentricity εa and the direction θεa of the receiving surface 1a from the paraxial curvature center positions of both surfaces of the lens 1 to be tested and the surface top position of the receiving surface 1a. The calculation method will be described with reference to FIGS.
As a first step, the paraxial curvature center position 1oa of the receiving surface 1a and the paraxial curvature center value 1ob of the opposite surface 1b of the receiving surface are set as x and y, respectively, as shown in FIGS. 2 (d) and (g). Break down into values. Each numerical value is obtained by the same formula as formulas (1) to (4).
[0108]
As a second step, the height Zo from 1 oa to 1 ob on the z-axis in FIG. 2 (a) is calculated in consideration of the amount of eccentricity of the paraxial curvature on both sides. This height Zo is according to the following equation.
[Formula 40]

[0109]
The result of the expression (8) 'is the same as Zo in (8) when the aspherical eccentric amount of the opposite surface 1b of the receiving surface is obtained first, and may be omitted.
[0110]
As a third step, the height Za from 1 oa to 1 ta on the z axis in FIG. 2 (a) is calculated in consideration of the surface top shift amount of the receiving surface 1a and the eccentric amount of the receiving surface 1a. This height Za is according to the following equation.
[Expression 41]

[0111]
In the subsequent steps, calculations are performed separately for the xz plane and the yz plane. Here, as an example, the calculation on the xz plane is performed first, and then the calculation on the yz plane is performed. In each step, calculation may be performed alternately on the xz plane and the yz plane.
[0112]
As a fourth step, the x component εax of the aspheric axis eccentricity is calculated from the aspheric axis rax with respect to the z axis in the xz plane and the inclination of the optical axis 1oax-1obx. As shown in FIG. 6A, εax is obtained by the following equation.
[Expression 42]

[0113]
As a fifth step, a perpendicular line is drawn from the aspherical surface top 1tax to the optical axis 1oax-1obx on the xz plane, and the length Lax is calculated. As shown in FIG. 6A, Lax is according to the following equation.
[Expression 43]

[0114]
The fourth and fifth steps are also applied to the yz plane, a perpendicular line is drawn from the aspherical surface top 1tay to the optical axis 1oay-1oby on the yz plane, and the length Lay is calculated. As shown in FIG. 6B, Lay is according to the following equation.
(44)

[0115]
As a sixth step, the inclination of the aspheric axis ra relative to the optical axis 1oa-1ob, that is, the aspheric eccentricity εa is calculated. Εa is obtained by the following equation as shown in FIGS.
[Equation 45]

[0116]
As a seventh step, the eccentric direction θa of the aspherical axis ra with respect to the optical axis 1oa-1ob is calculated. θa is obtained by the following equation because the aspherical surface top is separated from the optical axis by Lay in the x direction and Lay in the y direction as shown in FIGS.
[Equation 46]

[0117]
Through the above steps, the aspheric eccentricity and direction of the receiving surface 1a with respect to the optical axis 1oa-1ob can be accurately obtained.
[0118]
As described above, according to the first modification, the test surface shape measuring unit (displacement sensor unit) 6a and the test surface shape measuring unit (displacement sensor unit) 6b are installed above and below the test lens 1, respectively. Since the angle of inclination of the aspheric axis related to both sides can be detected exclusively, the aspheric decentering amount of each of the upper and lower surfaces can be measured without inverting the test lens, and in order to invert the test lens No need to interrupt measurement work.
[0119]
(Modification 2)
The first embodiment may be further modified as follows, and an effect equivalent to or higher than that of the first embodiment can be expected.
FIG. 7 shows a schematic configuration of an aspheric lens decentration measuring apparatus according to this modification.
As shown in the figure, the eccentricity measuring device 2 includes a test lens receiving portion 3 that rotatably holds the test lens 1 and a rotating lens support member for rotating the test lens receiving portion 3 shown in a vertical section. 4 and the paraxial eccentricity measurement for detecting the eccentricity of the paraxial curvature center of the surface 1b opposite to the receiving surface of the lens 1 with respect to the rotational axis 9 of the rotating lens support member 4 illustrated in the vertical section in the same manner. Part 5a, a paraxial eccentricity measuring unit 5b for detecting the amount of eccentricity of the paraxial curvature center of the receiving surface 1a of the lens 1 to be tested with respect to the rotating shaft 9 of the rotating lens support member 4, and a lens receiving surface for the rotating shaft 9 The surface shape measurement unit (displacement sensor unit) 6 for detecting the inclination angle of the aspherical axis on the opposite surface 1b of the rotation surface, the rotation angle measurement unit 7 for detecting the rotation angle of the rotation shaft 9, and the above-mentioned Calculate the measured values of the paraxial eccentricity measurement unit 5, the surface shape measurement unit (displacement sensor unit) 6, and the rotation angle measurement unit 7. That the arithmetic unit 8, and is composed of.
[0120]
That is, in Modification 2, in order to detect the amount of decentering of the paraxial curvature center related to both surfaces of the lens 1 to be examined, the paraxial eccentricity measuring unit 5a and the paraxial decentering measuring unit 5b are each configured exclusively for the lens to be examined. It is installed above and below 1 respectively.
Note that the contact portions 3a and 3b of the lens receiving portion 3 with the lens 1 to be tested are substantially concentrically processed with respect to the rotating shaft 9 of the rotating lens support member 4 as described above. The rotating lens support member 4 is also processed substantially concentrically with respect to the rotating shaft 9.
[0121]
A test lens receiving portion 3 is installed on the upper surface of the rotating lens support member 4, and receives the test lens 1 at an inner diameter side edge 3a or an outer diameter side edge 3b on the upper end surface of the lens receiving portion. Since the inner diameter edge 3 a and the outer diameter edge 3 b are processed concentrically with respect to the rotation shaft 9, the centers of the respective edges 3 a and 3 b exist on the rotation shaft 9.
The axis indicated by 10a is the detection axis of the aspherical axis of the opposite surface 1b of the receiving surface, and the axis indicated by 10b is the detection axis of the aspherical axis of the receiving surface 1a. The point indicated by 1 oa is the paraxial curvature center on the receiving surface side of the test lens 1, and the point indicated by 1 ob is the paraxial curvature center on the surface opposite to the receiving surface of the test lens 1.
[0122]
The paraxial eccentricity measuring unit 5a is installed on the upper surface of the test lens 1 so that its optical axis is coaxial with the rotational axis 9 of the rotating lens support member 4. Similarly, the paraxial eccentricity measuring unit 5b is provided on the lower surface of the test lens 1. The optical axis of the rotating lens support member 4 is installed coaxially with the rotating shaft 9.
As shown in the vertical cross section, the rotating lens support member 4 is also formed with a hollow central portion in the vicinity of the rotating shaft as shown in the drawing so as not to scatter the measurement light beam of the paraxial eccentricity measuring portion 5b.
The rotation angle measurement unit 7 is disposed so as not to scatter the measurement light beam of the paraxial eccentric measurement unit 5b, and although not shown, the rotation angle of the rotation lens support member 4 is determined by the belt and the pulley. , The rotation angle of the rotating lens support member 4 is detected.
[0123]
Although not shown in FIG. 7, the paraxial eccentricity measuring units 5a and 5b are provided with a light source, an optical system, an image pickup device, and an optical path switching means for distributing a light beam in two directions of the light source and the image pickup device. ing. The light beam emitted from the light source irradiates a light beam that is condensed at the paraxial curvature center of the test surface of the test lens 1 by the optical system. The optical system inside the paraxial decentering measurement units 5a and 5b moves and switches a part of the lens group constituting the optical system so that the condensing point of the light beam to be irradiated can be changed according to the curvature of the test surface. It has a possible configuration.
[0124]
The light beams irradiated from the paraxial eccentricity measuring units 5a and 5b and reflected by the respective test surfaces return to the same optical path, enter the paraxial eccentricity measuring units 5a and 5b, and are bent by the optical path switching means existing in the optical path. Then, an image is formed on the image sensor to form a spot-like image. In the case where the test surface is not decentered at all, even if the reflected light of the light beam applied to the test surface is observed with the image sensor while rotating the test lens 1, the spot does not sway.
[0125]
When the test surface is decentered with respect to the rotation axis, when the reflected light is observed while rotating the test lens 1, the image sensor observes that the spot rotates with a radius corresponding to the amount of eccentricity. it can.
The amount of eccentricity and the direction of eccentricity of the surface to be detected can be detected from the rotation radius of the spot and the direction from the rotation center of the spot in the origin state of the lens to be detected.
[0126]
Specifically, by inputting the signals from the paraxial eccentricity measurement units 5a and 5b and the rotation angle measurement unit 7 to the calculation unit 8, the proximity of the test surface to the angle change when the test lens 1 is rotated is measured. By measuring the change in position on the image sensor in the paraxial eccentricity measuring units 5a and 5b with the center of axial curvature, the amount of eccentricity and the direction of eccentricity of the paraxial center of curvature of each test surface are detected. The test surface shape measurement unit (displacement sensor unit) 6 detects the amount of displacement of the test surface 1b in the direction of the detection axis 10a accompanying the rotation of the test lens 1.
[0127]
Although the configuration is not shown in FIG. 7, the light beam, which is composed of a laser light source, an interference optical system, and a fiber, is irradiated on the test surface from the fiber exit end face again from the fiber. The interference fringes change due to the change in the displacement, which is incident on the sensor unit) 6, and the amount of displacement is detected by the light receiving sensor.
Further, there is a fulcrum for rotational movement of the test surface shape measuring unit (displacement sensor unit) 6 on the rotation axis 9 of the rotating lens support member 4, and the method of measuring the measurement surface of the test surface of the test lens 1 around that is the center. The detection axis 10 can be adjusted to coincide with the line, and the height of the fulcrum position can be moved on the rotation axis 9 according to the lens 1 to be examined. In addition, the height of the test surface shape measuring unit (displacement sensor unit) 6 in the direction of the detection axis 10 can be changed according to the shape of the test lens 1.
[0128]
By inputting output signals from the test surface shape measurement unit (displacement sensor unit) 6 and the rotation angle measurement unit 7 to the calculation unit 8, the detection axis 10 direction relative to the angle change when the test lens 1 is rotated is measured. Can measure height changes.
In the second modification, the test lens 1 having a double-sided convex aspherical shape is described. However, the present invention can be similarly applied to a test lens having a double-sided or one-sided concave aspherical or spherical surface. Needless to say.
[0129]
In the eccentricity measuring apparatus modified as described above, when alignment is performed while rotating the test lens 1 with the rotating lens support member 4 while supporting the test lens 1 with the test lens receiving portion 3, The center of curvature 1oa of the receiving surface 1a is theoretically always aligned with the axis of the rotating shaft 9 when the receiving surface 1a is a spherical surface. However, when the receiving surface 1a is an aspherical surface, 7 When the support point 3b of the lens receiving part 3 is equidistant from the top of the receiving surface 1a, the paraxial curvature center 1oa is on the rotation axis 9, but when the relationship does not hold, The paraxial center of curvature 1oa is not necessarily on the axis of the rotating shaft 9.
[0130]
While rotating the test lens 1 with the rotating lens support member 4, the amount of eccentricity with respect to the rotation axis 9 of the paraxial center of curvature 1ob of the opposite surface 1b of the receiving surface is detected via the paraxial eccentricity measuring unit 5a. The position of the test lens 1 is adjusted so that becomes approximately 0. The eccentricity adjustment here does not require the paraxial center of curvature 1ob to exactly coincide with the rotation axis 9, but when measuring the amount of eccentricity of the paraxial center of curvature 1oa of the receiving surface 1a, the eccentricity of the opposite surface 1b of the receiving surface This is done because the smaller the amount, the higher the detection accuracy.
[0131]
A rotation angle measuring unit 7 is connected to the rotating lens support member 4, and a reference is set for the rotation direction of the lens 1 to be measured, and the eccentric direction of the paraxial curvature center is measured. After the rough centering adjustment of the surface 1b opposite to the receiving surface of the lens 1 to be tested is completed, the paraxial center of curvature 1oa of the receiving surface 1a of the lens 1 to be tested is rotated by the paraxial eccentricity measuring unit 5b in the same manner as before. The amount of eccentricity and the direction of eccentricity are detected.
As described above, using the output results of the paraxial eccentricity measuring units 5a and 5b and the rotation angle measuring unit 7, the eccentric amounts δa and δb and the eccentric directions of the paraxial curvature centers of the receiving surface 1a and the opposite surface 1b of the receiving surface θa and θb can be calculated by the calculation unit 8.
[0132]
2 (d) and 2 (g), the paraxial curvature sphere center position when the lens 1 to be tested is at the rotation origin position is converted into a value in the xy plane from the decentering amount and decentering direction of the paraxial curvature center. Is possible.
The paraxial curvature center position of the receiving surface 1a can be expressed by the following equation as shown in FIG.
[Equation 47]

[0133]
The paraxial curvature center position of the opposite surface 1b of the receiving surface is obtained by the calculation unit 8 using the following conversion formula as shown in FIG.
[Formula 48]

[0134]
Next, according to the surface 1b opposite to the receiving surface of the lens 1 to be detected, the angle of the detection axis 10 of the displacement sensor unit 6 is made to coincide with the normal of the surface 1b to be detected. The adjustment is also made according to the test surface 1b of the test lens 1. In this state, the test lens 1 is rotated by the rotating lens support member 4, the change in height in the direction of the detection axis 10a is output, and the change in the angle of the test lens 1 is output by the rotation angle measurement unit 7. Type in 8.
The calculation unit 8 converts the detection value of the surface shape measurement unit (displacement sensor unit) 6 into the direction of the rotation axis 9 of the rotating lens support member 4.
[0135]
A measurement radius r shown in FIG. 7 is calculated from the fulcrum position of the angle of the detection axis 10 of the test surface shape measurement unit (displacement sensor unit) 6 and the shape and positional relationship of the test lens 1. From this measurement radius r and information of the rotation angle measurement unit 7 and information obtained by decomposing the output of the test surface shape measurement unit (displacement sensor unit) 6 in the direction of the rotation axis 9, the three-dimensional coordinate data of the x, y and z coordinates is obtained. Convert. The measured three-dimensional coordinate data is compared with the design formula of the test surface 1b.
At this time, the detection shaft 10 of the surface shape measurement unit (displacement sensor unit) 6 is inclined by θa with respect to the rotation shaft 9, so in order to compare with the design formula, the direction of the rotation axis Needs to be converted to displacement.
[0136]
[Formula 49]

[0137]
When aspherical axis detection is performed at a point separated from the rotation axis 9 by r, the information in the height direction shown in equation (5) is separated into x and y by the following equation and compared with the design equation. Do. Here, the output of the rotation angle measurement unit 7 for each measurement point is θrot.
[Equation 50]

[0138]
In FIG. 7, the detection axis 10 is inclined with respect to the rotation axis 9, but the inclination θ is 0 degree, that is, in a state parallel to the rotation axis 9, the surface shape measurement unit (displacement sensor unit) The same calculation is true even if the detection axis 10 of 6) is configured.
As a method of comparing the three-dimensional coordinate data with the design formula, for example, the measurement three-dimensional data may be shifted and tilted on the design formula of the surface 1b to be measured so that the difference between the two is minimized. Substituting the amount given by equations (1) and (2) as the shift amount, fixing the shift in the x and y directions, and shifting in the tilt and z directions in the x and y directions around the center of the ball A state where the difference between the two is minimized is detected.
[0139]
Thereafter, by calculating backward from the tilt amount and the shift amount of the measured three-dimensional data, the amount of movement 1tb in the xy plane of the aspheric surface top of the opposite surface 1b of the receiving surface with respect to the rotating shaft 9 can be obtained. As shown in FIG. 2E, the amount of movement 1tb in the x direction is 1tbx, and the amount in the y direction is 1tby. Also, assuming that the tilt amount in the x direction is Abx and the tilt amount in the y direction is Aby, the shift amounts 1tbx and 1tby of the aspheric surface top can be obtained by the following equations.
[Formula 51]

[0140]
Next, the calculation unit 8 calculates the aspheric eccentricity εb and the direction θεb of the test surface 1b from the paraxial curvature center positions of both surfaces of the test lens 1 and the top position of the test surface 1b.
The calculation method will be described with reference to FIGS. 2 (a) to (g).
As a first step, the paraxial curvature center position 1oa of the receiving surface 1a and the paraxial curvature center value 1ob of the opposite surface 1b of the receiving surface are respectively set to x and y as shown in FIGS. 2 (d) and 2 (g). Disassembled into Each numerical value is obtained by the same formula as formulas (1) to (4).
[0141]
As a second step, the height Zo from 1 oa to 1 ob on the z-axis in FIG. 2A is calculated in consideration of the amount of eccentricity of the paraxial curvature of both surfaces. This height Zo is according to the following equation.
[Formula 52]

Here, ra represents the paraxial radius of curvature of the receiving surface 1a, rb represents the paraxial radius of curvature of the receiving surface 1b, and d represents the lens thickness.
[0142]
As a third step, the height Zb from 1ob to 1tb on the z-axis in Fig. 2 (a) is calculated in consideration of the top shift amount of the opposite surface 1b of the receiving surface and the eccentric amount of the receiving surface. To do. This height Zb is according to the following equation.
[53]

[0143]
In the subsequent steps, calculation is performed separately for the xz plane and the yz plane. Here, as an example, the calculation on the xz plane is performed first, and then the calculation on the yz plane is performed. However, this is performed for convenience of explanation, and the yz plane may be calculated first. In each step, the xz plane and the yz plane may be calculated alternately.
As a fourth step, the x component εbx of the aspherical axis eccentricity is calculated from the aspherical axis rbx with respect to the z axis in the xz plane and the inclination of the optical axis 1oax-1obx. As shown in FIG. 3A, the x component εbx is expressed by the following equation.
[Formula 54]

[0144]
As a fifth step, a perpendicular line is drawn from the aspherical surface top 1tbx to the optical axis 1oax-1obx on the xz plane, and the length Lbx is calculated. As shown in FIG. 3 (a), Lbx is according to the following equation.
[Expression 55]

[0145]
The fourth and fifth steps are also applied to the yz plane, a perpendicular line is drawn from the aspheric surface top 1tby to the optical axis 1oay-1oby on the yz plane, and the length Lby is calculated. As shown in FIG. 3 (b), Lby is according to the following equation.
[Expression 56]

[0146]
As a sixth step, the inclination of the aspherical axis rb with respect to the optical axis 1oa-1ob, that is, the aspherical eccentricity εb is calculated. εb is obtained by the following equation as shown in FIGS.
[Equation 57]

[0147]
As a seventh step, the eccentric direction θb of the aspherical axis rb with respect to the optical axis 1oa-1ob is calculated. θb can be obtained by the following equation because the aspherical surface top is separated from the optical axis by Lbx in the x direction and Lby in the y direction as shown in FIGS. 3 (a) and 3 (b).
[Formula 58]

[0148]
By the above steps, the aspheric eccentricity and direction of the surface 1b opposite to the receiving surface with respect to the optical axis 1oa-1ob can be accurately obtained.
If the test lens 1 is installed upside down on the test lens receiving portion 3 and the same detection and calculation are performed, the aspheric decentering amount εa and the direction θa of the surface opposite to the surface obtained above are accurately determined. Can be sought.
[0149]
As described above, according to the second modification example, the paraxial decentering measuring unit 5a and the paraxial decentering measuring unit 5b are provided on the upper and lower sides of the test lens 1, respectively. Since the eccentric amount and direction of the paraxial curvature center of the receiving surface 1a can be detected without passing through the opposite surface 1b of the receiving surface 1a, it becomes possible to obtain the paraxial curvature center with high accuracy and the aspheric eccentricity amount. Can be measured with high accuracy.
In addition, various modifications can be made without departing from the scope of the present invention.
[0150]
As mentioned above, although demonstrated based on embodiment and its modification, the following invention is contained in this specification.
(1) The test lens can be measured not only when both surfaces are aspherical but also when both surfaces or one surface is aspherical or spherical. Can be provided.
(2) The test lens can be measured not only on a convex aspherical surface on both sides but also on a concave aspherical or spherical surface on one or both sides. 1 can be provided.
[0151]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an aspheric decentering amount of an aspheric lens and its measuring method and measuring device easily and with high accuracy.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing the configuration of an aspheric lens decentration measuring apparatus as a first embodiment of the present invention.
[Fig. 2] Fig. 2 (a) to (g) show the way of thinking when calculating the aspheric eccentricity value.
(a) is an explanatory diagram showing the paraxial center of curvature and the aspherical surface apex of both surfaces of the lens in three dimensions x, y, z
(b) is an explanatory view showing the paraxial curvature center and the aspherical surface top of both lens surfaces in the xz plane,
(c) is an explanatory view showing the paraxial curvature center and the aspherical surface apex on both surfaces of the lens in the yz plane;
(d) is an explanatory view showing the position of the paraxial center of curvature of the receiving surface on the xy plane,
(e) is an explanatory view showing the position of the top of the aspherical surface opposite to the receiving surface in the xy plane;
(f) is an explanatory view showing the position of the aspheric surface top of the receiving surface in the xy plane,
(g) is explanatory drawing which shows the position of the paraxial curvature center of the opposite surface of a receiving surface in xy plane.
FIGS. 3 (a) and 3 (b) are explanatory diagrams illustrating the concept of obtaining an aspheric eccentricity value.
FIG. 4 is a flowchart showing a calculation procedure related to a method for measuring the eccentricity of an aspheric lens.
FIG. 5 is a configuration diagram schematically showing the configuration of an aspheric lens decentration measuring apparatus as a modification of the first embodiment.
FIGS. 6A and 6B are explanatory diagrams showing shift amounts 1tax and 1tay of the aspherical surface top. FIG.
FIG. 7 is a configuration diagram schematically showing a configuration of an aspheric lens decentration measuring apparatus as another modification of the first embodiment.
FIGS. 8A to 8E show an aspheric lens having an aspheric surface,
(a) is an explanatory diagram showing the deviation between the two aspherical axes and the optical axis when both surfaces are aspherical,
(b) is an explanatory diagram showing the deviation between the aspherical axis and the optical axis when only one side is aspherical,
(c)-(e) is a graph showing the direction of aspheric eccentricity (direction from the origin to the top of the aspheric surface).
FIG. 9 is a schematic configuration diagram showing a conventional aspheric lens decentration measuring apparatus.
[Explanation of symbols]
1 ... Test lens (Aspherical lens to be measured),
1a, 1b ... surface to be measured (measurement lens surface: receiving surface, opposite surface),
1oa, 1ob… Paraxial center of curvature,
1ta, 1tb ... the top,
2 ... Eccentricity measuring device,
3 ... Test lens receiving part,
3a, 3b ... contact part (inner diameter, outer diameter edge),
4… Rotating lens support member,
5, 5a, 5b ... Paraxial eccentricity measurement unit,
6, 6a, 6b ... Displacement sensor part (surface shape measuring part to be tested),
7 ... Rotation angle measurement unit,
8 ... arithmetic unit (CPU: includes various programs),
9 ... rotary axis,
10 ... Detection axis.
S10 to S40: Calculation procedure for eccentricity measurement.

Claims (7)

A lens receiver for holding the lens to be examined;
A rotating lens support member configured to freely rotate the lens receiving portion;
A paraxial eccentricity measuring means for detecting the amount and direction of the eccentricity of the paraxial center of curvature of both surfaces of the lens to be measured with respect to the rotational axis of the rotating lens support member;
A test surface shape measuring means for detecting the shape of the test surface;
Rotation angle measuring means for detecting the rotation angle of the lens to be examined;
The data obtained by rotating the lens to be measured and measured by the surface shape measuring means is compared with the design formula of the surface to be tested, and the relative shift amount and tilt amount that minimize the difference between the two are obtained. And calculating the position of the surface apex with respect to the rotation axis from the shift amount and the tilt amount, and the amount of eccentricity between the surface apex position and the paraxial curvature center of both surfaces of the test lens measured by the paraxial eccentricity measuring means, and Calculating means for calculating the amount and direction of inclination of the aspherical axis with respect to the optical axis of the lens to be examined from the direction;
An aspherical lens eccentricity measuring device comprising: The test surface shape measuring means is composed of two test surface shape measuring units respectively installed in the vicinity of both surfaces of the test lens,
The aspherical lens eccentricity measuring apparatus according to claim 1, wherein the shape of the test surface on both sides of the aspherical lens is detected independently. The paraxial decentering measuring means is composed of two paraxial decentering measuring units respectively installed in the vertical and vertical directions of the test lens, and the measuring light beam is opposite to the receiving surface of the test lens. Configured to not penetrate
The aspherical lens eccentricity measuring apparatus according to claim 1, wherein the rotating lens support member is substantially concentrically processed with respect to the rotating shaft. Paraxial eccentricity measuring means for detecting the amount of eccentricity of the paraxial curvature center of both surfaces of the test lens, test surface shape measuring means for detecting the shape of the test surface of the test lens, and the rotation angle of the test lens In the eccentricity measuring method of the aspherical lens in the eccentricity measuring device provided with the rotation angle measuring means for detecting
A paraxial curvature center detecting step of detecting an eccentric amount and direction of a paraxial curvature center of both surfaces of the lens to be tested with respect to the rotation axis by the paraxial eccentricity measuring means;
A shape measuring step for measuring the shape of the test surface by the test surface shape measuring means and a surface having a test surface shape in which the measured test surface shape is compared with a predetermined design formula, and the difference between the two is minimized. A first calculation step for calculating the position of the apex;
A second calculation step for determining the eccentricity of the aspherical lens from the decentering amount and direction of the paraxial curvature center of both surfaces of the test lens and the position of the surface top;
A method for measuring the eccentricity of an aspherical lens. The first calculation step compares the measured test surface shape with a predetermined design formula, and calculates the top position of the test surface shape so that the relative shift amount and tilt amount of both are minimized. The method of measuring eccentricity of an aspherical lens according to claim 4, wherein The second calculation step includes an optical axis connecting the paraxial curvature center of the target lens both surfaces, and the aspherical axis connecting the paraxial curvature center of the aspheric surface including the position and said surface top of a surface apex, 6. The method for measuring the eccentricity of an aspheric lens according to claim 4, wherein the tilt amount and direction are calculated. The inclination and direction of the aspherical axis of the first surface with respect to the optical axis connecting the paraxial curvature centers of both surfaces of the test lens are calculated, and the test lens is inverted to connect the paraxial curvature centers of both surfaces. The method for measuring the eccentricity of an aspheric lens according to any one of claims 4 to 6, wherein an inclination amount and direction of an aspheric axis of the second surface with respect to the optical axis are calculated.

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