JP3698179B2 - Microscope objective lens - Google Patents
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- JP3698179B2 JP3698179B2 JP17615796A JP17615796A JP3698179B2 JP 3698179 B2 JP3698179 B2 JP 3698179B2 JP 17615796 A JP17615796 A JP 17615796A JP 17615796 A JP17615796 A JP 17615796A JP 3698179 B2 JP3698179 B2 JP 3698179B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、顕微鏡に用いられる対物レンズに関する。特に中高倍率（約１０倍以上）の像面が平坦なアクロマート級またはセミアポクロマート級顕微鏡用対物レンズに関する。
【０００２】
【従来の技術】
従来、中高倍率のアクロマート級対物レンズとしては、中倍率においてはリスター型、高倍率においてはアミチ型のものが知られている。
これらの対物レンズよりも像面の平坦性（プラン性）を向上させたものとしては、中倍率においては、トリプレット型、エルノスター型、ガウス型などのレンズタイプのものが用いられており、高倍率においては、強い凹面を物体側に向けた正アプラナチックレンズを最も物体側に配置し、かつ凹面を像側に向けた厚いメニスカスレンズを最も像側に配置したベーゲボールド型や、正アプラナチックレンズを最も物体側に配置し、かつ互いに向かい合った凹面を持つ２組の厚いメニスカスレンズの組を最も像側に配置したタイプなどが知られている。
【０００３】
【発明が解決しようとする課題】
ここで、上述のごとき従来の顕微鏡用対物レンズにおいては、光学性能を重視するあまり、この対物レンズを構成する各レンズ素子の曲率半径、レンズ中心厚及び硝材がそれぞれ異なるように構成している。
従って、従来の顕微鏡用対物レンズの製造においては、各レンズ素子をそれぞれ異なる曲率半径、レンズ中心厚となるように加工する必要があり、さらには、多種類の硝材を手配する必要があるため、コストの上昇が避けられなかった。
【０００４】
そこで、本発明は、良好な結像性能を維持しつつ大幅なコストダウンを図ることが可能な中高倍率用の顕微鏡用対物レンズを提供することを目的とする。
【０００５】
【課題を解決するための手段】
上述の目的を達成するために、本発明による顕微鏡用対物レンズは、物体側より順に、物体側に凹面を向けたレンズ素子を含む第１レンズ群と、
第１の正レンズ素子とこの第１の正レンズ素子よりも像側に配置される第２の正レンズ素子とを含み全体として正屈折力を有する第２レンズ群と、
全体として負屈折力を有する第３レンズ群とを有し、
第１の正レンズ素子の物体側レンズ面の曲率半径をＲ１ａ、第１の正レンズ素子の像側レンズ面の曲率半径をＲ１ｂ、第１の正レンズ素子の中心厚をＤ１、第１の正レンズ素子を構成する光学材料の屈折率をＮ１、第２の正レンズ素子の物体側レンズ面の曲率半径をＲ２ａ、第２の正レンズ素子の像側レンズ面の曲率半径をＲ２ｂ、第２の正レンズ素子の中心厚をＤ２、第２の正レンズ素子を構成する光学材料の屈折率をＮ２とするとき、
（１） ｜Ｒ１ａ｜＝｜Ｒ２ｂ｜
（２） ｜Ｒ１ｂ｜＝｜Ｒ２ａ｜
（３） Ｄ１＝Ｄ２
（４） Ｎ１＝Ｎ２
（５） ｜Ｒ１ａ｜＞｜Ｒ１ｂ｜
（６） ｜Ｒ２ａ｜＜｜Ｒ２ｂ｜
の各条件を満足するものである。
【０００６】
なお、本発明において、顕微鏡用対物レンズが無限遠系の場合には、像側とは顕微鏡用対物レンズを挟んで物体側とは反対側のことを指す。
【０００７】
【発明の実施の形態】
まず、本発明における基本構成について説明する。本発明にかかる顕微鏡用対物レンズの第１レンズ群中の物体側に凹面を向けたレンズ素子は、第１レンズ群で発生する球面収差を最小限に抑え、かつ負のペッツバール和を発生させることで像面の平坦性の向上に寄与している。
【０００８】
また、第２レンズ群は、正の屈折力を有しており、本発明では、第２レンズ群中の第１および第２の正レンズ素子を上記条件式（１）〜（６）を同時に満足するように構成している。
条件式（１）〜（４）は、本発明の顕微鏡用対物レンズの第２レンズ群における２枚の正レンズ（第１および第２の正レンズ素子）が、共に同じレンズ素子から構成されていることを意味する。従って、本発明にかかる顕微鏡用対物レンズを製造する際には、１種類の正レンズ素子を加工するだけで、顕微鏡用対物レンズを構成するレンズ素子のうち２枚のレンズ素子が加工できることになり、使用する硝種の数が減り、さらにレンズの曲率及び中心厚を揃えることできるためレンズ加工治具も減り、全体の工数も減ることになり、大幅なコスト低減を図ることができる。
【０００９】
そして、条件式（５）および（６）は、第１および第２の正レンズ素子において曲率の強いレンズ面を互いに向き合わせて配置することを意味しており、これにより、第２レンズ郡内における各レンズ面で担う屈折力が分散される。上記条件式（５）および（６）を満足しない場合には、第１レンズ群及び第２レンズ群から発生する球面収差およびコマ収差補正が困難となる。
【００１０】
第３レンズ群は、全体として負屈折力をもつことで、第１レンズ群中の物体側に向けられた凹面と共に、像の平坦性向上に寄与している。さて、本発明にかかる顕微鏡用対物レンズは、第２レンズ群中の第１の正レンズ素子のアッベ数をνｄ１とし、第２レンズ群中の第２の正レンズ素子のアッベ数をνｄ２とするとき、以下の条件式（７）および（８）を満足するように構成されることが好ましい。
（７） νｄ１≧６２
（８） νｄ２≧６２
これらの条件式（７）および（８）は、第１レンズ群及び第２レンズ群で発生する軸上色収差および倍率色収差を抑えるためのものであり、これらの条件式（７）および（８）の下限を下回る場合には、顕微鏡用対物レンズ全系の軸上色収差および倍率色収差が補正不足となるため好ましくない。
【００１１】
また、本発明にかかる顕微鏡用対物レンズは、第１の正レンズ素子の物体側レンズ面に入射する近軸光線の換算傾角をαｉｎ、第１の正レンズ素子の物体側レンズ面に入射する近軸光線の入射高をｈｉｎ、第２の正レンズ素子の像側レンズ面から射出される近軸光線の換算傾角をαｏｕｔ、第２の正レンズ素子の像側レンズ面から射出される近軸光線の入射高をｈｏｕｔ、第３レンズ群から射出される近軸光線の入射高をｈｅｎｄとするとき、
（９） −１＜αｏｕｔ／αｉｎ＜−０．１５
（１０） ｜ ｈｉｎ／ ｈｅｎｄ ｜＞１
（１１） ｜ ｈｏｕｔ ／ ｈｅｎｄ ｜＞１
の各条件を満足するように構成されることが好ましい。
【００１２】
なお、換算傾角の定義については、「レンズ設計法」松居吉哉著 共立出版発行 第２０頁に記載されている。
上記条件式（９）は、第２レンズ群中の第１の正レンズ素子と第２の正レンズ素子とによって挟まれるレンズ群の横倍率を規定するものである。ここで、条件式（９）の下限を下回る場合には、第２レンズ群全体の屈折力が強くなり過ぎるため球面収差が著しくアンダーになるため好ましくない。ここで、このアンダーな球面収差を無理に補正しようとすると、第２レンズ群における各レンズ面の曲率が強くなるため、外向性のコマ収差が発生し、さらには短波長の球面収差が補正過剰となるため好ましくない。
【００１３】
一方、条件式（９）の上限を超える場合には、第２レンズ群全体の屈折力が弱くなり過ぎるため、第１レンズ群からの発散光束を十分に収斂光束にすることができないため好ましくない。この場合においては、内向性のコマ収差が発生し、さらには、像面の平坦性を確保することができないため好ましくない。
条件式（１０）および（１１）は、第２レンズ群と第３レンズ群との屈折力配置に関する物であって、この条件式（１０）および（１１）の下限を下回る場合には、顕微鏡用対物レンズの作動距離が短くなり、さらには像面の平坦性も確保できなくなるため好ましくない。
【００１４】
また、本発明にかかる顕微鏡用対物レンズは、第１の正レンズ素子の物体側レンズ面に入射する近軸光線の換算傾角をαｉｎ、第２の正レンズ素子の物体側に入射する近軸光線の換算傾角をαｍｉｄとするとき、
（１２） ０≦αｍｉｄ／αｉｎ＜０．６
の条件を満足するように構成されることが好ましい。
【００１５】
上記条件式（１２）は、第１レンズ群と第２レンズ群との屈折力配置に関するものであって、条件式（１２）の下限を下回る場合には、第２レンズ群全体の屈折力が強大になり過ぎるため、第２レンズ群を構成する各レンズ面の曲率半径が強くなる。このとき、外向性のコマ収差が発生し、さらには短波長の球面収差が補正過剰となるため好ましくない。
【００１６】
一方、上限式（１２）の上限を超える場合には、第２レンズ群から射出される軸上光束の入射高が高くなり過ぎるため、第３レンズ群の負屈折力を強める必要が生じる。このときには、像面が正側へ倒れ、外向性のコマ収差が発生し、さらには倍率色収差が補正不足となるため好ましくない。
さて、本発明にかかる顕微鏡用対物レンズにおいては、第２レンズ群中の第１の正レンズ素子に接合される第１の負レンズ素子と、第２レンズ群中の第２の正レンズ素子に接合される第２の負レンズ素子とをさらに有するように構成されることが好ましい。
【００１７】
この場合、第１の負レンズ素子の第１の正レンズ素子とは反対側のレンズ面の曲率半径をＲ３ａ、第１の負レンズ素子の第１の正レンズ素子側のレンズ面の曲率半径をＲ３ｂ、第１の負レンズ素子の中心厚をＤ４、第１の負レンズ素子を構成する光学材料の屈折率をＮ４、第２の負レンズ素子の第２の正レンズ素子側のレンズ面の曲率半径をＲ３ａ、第２の負レンズ素子の第２の正レンズ素子とは反対側のレンズ面の曲率半径をＲ４ｂ、第２の負レンズ素子の中心厚をＤ４、第２の負レンズ素子を構成する光学材料の屈折率をＮ４とするとき、
（１３） ｜Ｒ３ａ｜＝｜Ｒ４ｂ｜
（１４） ｜Ｒ３ｂ｜＝｜Ｒ４ａ｜
（１５） Ｄ３＝Ｄ４
（１６） Ｎ３＝Ｎ４
の各条件を満足するように構成することが好ましい。
【００１８】
これらの条件式（１３）〜（１６）は、第２レンズ群中の第１および第２の正レンズ素子に接合される２つのレンズ素子（第３および第２の負レンズ素子）が、共に同じレンズ素子から構成されていることを意味する。この構成によれば、さらに使用する硝種の数が減り、さらにレンズの曲率及び中心厚を揃えることできるためレンズ加工治具も減り、全体の工数も減ることになり、大幅なコスト低減を図ることができる利点がある。
【００１９】
ここで、第１の正レンズ素子に接合される第１の負レンズ素子と、第２の正レンズ素子に接合される第２の負レンズ素子とを有する場合には、第１の負レンズ素子の物体側レンズ面に入射する近軸光線の換算傾角をαｉｎ、第１の負レンズ素子の物体側レンズ面に入射する近軸光線の入射高をｈｉｎ、第２の負レンズ素子の像側レンズ面から射出される近軸光線の換算傾角をαｏｕｔ、第２の負レンズ素子の像側レンズ面から射出される近軸光線の入射高をｈｏｕｔ、第３レンズ群から射出される近軸光線の入射高をｈｅｎｄとするとき、
（１７） −１＜αｏｕｔ／αｉｎ＜−０．１５
（１８） ｜ ｈｉｎ／ ｈｅｎｄ ｜＞１
（１９） ｜ ｈｏｕｔ ／ ｈｅｎｄ ｜＞１
の各条件を満足するように構成されることが好ましい。
【００２０】
上記条件式（１７）は、第２レンズ群中の第１の負レンズ素子と第２の負レンズ素子とによって挟まれるレンズ群の横倍率を規定するものである。ここで、条件式（１７）の下限を下回る場合には、第２レンズ群全体の屈折力が強くなり過ぎるため球面収差が著しくアンダーになるため好ましくない。ここで、このアンダーな球面収差を無理に補正しようとすると、第２レンズ群における各レンズ面の曲率が強くなるため、外向性のコマ収差が発生し、さらには短波長の球面収差が補正過剰となるため好ましくない。
【００２１】
一方、条件式（１７）の上限を超える場合には、第２レンズ群全体の屈折力が弱くなり過ぎるため、第１レンズ群からの発散光束を十分に収斂光束にすることができないため好ましくない。この場合においては、内向性のコマ収差が発生し、さらには、像面の平坦性を確保することができないため好ましくない。
条件式（１８）および（１９）は、第２レンズ群と第３レンズ群との屈折力配置に関する物であって、この条件式（１８）および（１９）の下限を下回る場合には、顕微鏡用対物レンズの作動距離が短くなり、さらには像面の平坦性も確保できなくなるため好ましくない。
【００２２】
また、第１の正レンズ素子に接合される第１の負レンズ素子と、第２の正レンズ素子に接合される第２の負レンズ素子とを有する場合には、第１の負レンズ素子の物体側レンズ面に入射する近軸光線の換算傾角をαｉｎ、第２の負レンズ素子の物体側に入射する近軸光線の換算傾角をαｍｉｄとするとき、
（２０） ０≦αｍｉｄ／αｉｎ＜０．６
の条件を満足するように構成されることが好ましい。
【００２３】
上記条件式（２０）は、第１レンズ群と第２レンズ群との屈折力配置に関するものであって、条件式（２０）の下限を下回る場合には、第２レンズ群全体の屈折力が強大になり過ぎるため、第２レンズ群を構成する各レンズ面の曲率半径が強くなる。このときには、外向性のコマ収差が発生し、さらには短波長の球面収差が補正過剰となるため好ましくない。
【００２４】
一方、条件式（２０）の上限を超える場合には、第２レンズ群から射出される軸上光束の入射高が高くなり過ぎるため、第３レンズ群の負屈折力を強める必要が生じる。このときには、像面が正側に倒れ、外向性のコマ収差が発生し、さらには倍率色収差が補正不足となるため好ましくない。
また、本発明にかかる顕微鏡用対物レンズにおいては、第１の正レンズ素子と第２の正レンズ素子との間に配置されて第１および第２の正レンズ素子に接合される負レンズ素子をさらに有するように構成されることが好ましい。この場合には、第１および第２の正レンズ素子に挟まれる負レンズ素子もその両側のレンズ面が同一曲率半径のものとなるため、その加工が容易になる利点がある。
【００２５】
なお、本発明でいう同一硝種、同一曲率半径及び同一中心厚の２枚の正レンズ或いは２枚の負レンズとは、それらのレンズが屈折率分布型レンズであることや非球面レンズであることを排除するものではない。例えば非球面レンズであるときには、２枚のレンズが同一の非球面形状であれば良く、屈折率分布型レンズであるときには、２枚のレンズにおける屈折率分布が同じであれば良い。
【００２６】
【実施例】
以下、図面を参照して本発明による顕微鏡用対物レンズの実施例を示す。図１〜図４はそれぞれ第１乃至第４実施例による顕微鏡用対物レンズのレンズ構成図である。
［第１実施例］
図１において、第１実施例の顕微鏡用対物レンズは、物体側から順に、物体側に凹面を向けた両凹形状の負レンズＬ１１およびこの負レンズＬ１１に接合された正レンズＬ１２からなる接合レンズ成分を有し全体として負屈折力の第１レンズ群Ｇ１と、強い凸面を像側へ向けた両凸形状の正レンズ（第１の正レンズ素子）Ｌ２１と、強い凸面を物体側へ向けた両凸形状の正レンズ（第２の正レンズ素子）Ｌ２２とを有する第２レンズ群Ｇ２と、凹面を像側へ向けた負メニスカスレンズＬ３１を有する第３レンズ群Ｇ３とから構成される。
［第２実施例］
図２において、第２実施例の顕微鏡用対物レンズは、物体側から順に、物体側に凹面を向けた両凹形状の負レンズＬ１１およびこの負レンズＬ１１に接合された正レンズＬ１２からなる接合レンズ成分を有し全体として正屈折力を有する第１レンズ群Ｇ１と、強い凸面を像側へ向けた両凸形状の正レンズ（第１の正レンズ素子）Ｌ２１と、強い凸面を物体側へ向けた両凸形状の正レンズ（第２の正レンズ素子）Ｌ２２ととを有する第２レンズ群Ｇ２と、強い凸面を物体側へ向けた両凸形状の正レンズＬ３１およびこの正レンズＬ３１に接合されて像側に強い凹面を向けた両凹形状の負レンズＬ３２からなる接合レンズ成分と、物体側に凹面を向けた負メニスカスレンズＬ３３と、物体側に凹面を向けた正メニスカスレンズＬ３４とを有し全体として負屈折力の第３レンズ群とから構成される。
［第３実施例］
図３において、第３実施例の顕微鏡用対物レンズは、物体側から順に、物体側に凹面を向けた正メニスカスレンズＬ１１と、同じく物体側に凹面を向けた正メニスカスレンズＬ１２とを有し全体として正屈折力を有する第１レンズ群Ｇ１と、像側に強い凸面を向けた両凸形状の正レンズ（第１の正レンズ素子）Ｌ２１、両凹形状の負レンズ素子Ｌ２２および物体側に強い凸面を向けた両凸形状の正レンズＬ２３（第２の正レンズ素子）Ｌ２３からなり全体として正屈折力の接合レンズ成分を有する第２レンズ群Ｇ２と、像側に凹面を向けた正メニスカスレンズＬ３１および像側に凹面を向けた負メニスカスレンズＬ３２からなり全体として負屈折力の接合レンズ成分を有する第３レンズ群Ｇ３とから構成される。
［第４実施例］
図４において、第４実施例の顕微鏡用対物レンズは、物体側から順に、像側に凸面を向けた平凸レンズＬ１１および物体側に凹面を向けた負メニスカスレンズＬ１２からなる接合レンズ成分と、像側に強い凸面を向けた両凸形状の正レンズＬ１３とを有し全体として正屈折力を有する第１レンズ群Ｇ１と、像側に強い凹面を向けたメニスカス形状の負レンズ（第１の負レンズ素子）Ｌ２１およびこの負レンズＬ２１に接合されて像側に強い凸面を向けた両凸形状の正レンズ（第１の正レンズ素子）Ｌ２２とからなる接合レンズ成分と、物体側に強い凸面を向けた両凸形状の正レンズ（第２の正レンズ素子）Ｌ２３およびこの正レンズＬ２３に接合されて物体側に強い凹面を向けたメニスカス形状の負レンズＬ２４とからなる接合レンズ成分とを有し全体として正屈折力の第２レンズ群Ｇ２と、像側に強い凸面を向けた両凸形状の正レンズＬ３１およびこの正レンズＬ３１に接合された両凹形状の負レンズＬ３２からなる接合レンズ成分を有し全体として負屈折力の第３レンズ群Ｇ３とから構成される。
次に、上記の各実施例の諸元を以下の表１〜４に示す。
【００２７】
表１〜４において、ｆは焦点距離、βは後述の第２対物レンズと組み合わせたときの横倍率、Ｎ．Ａ．は物体側の開口数である。また、各表において、ｒｉは第ｉ面の曲率半径、ｄｉは第ｉ面と第ｉ＋１面との間の面間隔、ｎｄｉは第ｉ面と第ｉ＋１面との間の媒質のｄ線（λ＝５８７．６ｎｍ）に対する屈折率（空白は媒質が空気であることを示す）であり、νｄｉは第ｉ面と第ｉ＋１面との間の媒質のｄ線（λ＝５８７．６ｎｍ）に対するアッベ数（空白は媒質が空気であることを示す）である。
【００２８】
【表１】
［第１実施例］
ｆ＝20mm
β＝-10×
Ｎ．Ａ．＝0.25
ｒ1 ＝ -12.264 ｄ1 ＝ 8.96 ｎｄ1 ＝1.6889 νｄ1 ＝31.1
ｒ2 ＝ +44.184 ｄ2 ＝ 5.33 ｎｄ2 ＝1.4978 νｄ2 ＝82.5
ｒ3 ＝ -14.935 ｄ3 ＝ 1.01
ｒ4 ＝ +88.709 ｄ4 ＝ 2.97 ｎｄ4 ＝1.5186 νｄ4 ＝70.0
ｒ5 ＝ -37.364 ｄ5 ＝ 0.53
ｒ6 ＝ +37.364 ｄ6 ＝ 2.97 ｎｄ6 ＝1.5186 νｄ6 ＝70.0
ｒ7 ＝ -88.709 ｄ7 ＝ 23.35
ｒ8 ＝ +31.604 ｄ8 ＝ 5.66 ｎｄ8 ＝1.5474 νｄ8 ＝53.5
ｒ9 ＝ +16.385
【００２９】
【表２】
［第２実施例］
ｆ＝20mm
β＝-10×
Ｎ．Ａ．＝0.30
ｒ1 ＝ -39.564 ｄ1 ＝ 8.07 ｎｄ1 ＝1.6200 νｄ1 ＝36.3
ｒ2 ＝ +76.081 ｄ2 ＝ 5.95 ｎｄ2 ＝1.4339 νｄ2 ＝95.2
ｒ3 ＝ -18.154 ｄ3 ＝ 0.16
ｒ4 ＝+104.670 ｄ4 ＝ 3.04 ｎｄ4 ＝1.4978 νｄ4 ＝82.5
ｒ5 ＝ -27.454 ｄ5 ＝ 0.17
ｒ6 ＝ +27.454 ｄ6 ＝ 3.04 ｎｄ6 ＝1.4978 νｄ6 ＝82.5
ｒ7 ＝-104.670 ｄ7 ＝ 0.18
ｒ8 ＝ +18.038 ｄ8 ＝ 7.32 ｎｄ8 ＝1.5186 νｄ8 ＝70.0
ｒ9 ＝ -76.185 ｄ9 ＝ 5.08 ｎｄ9 ＝1.6200 νｄ9 ＝36.3
ｒ10＝ +9.336 ｄ10＝ 2.89
ｒ11＝ -12.251 ｄ11＝ 1.03 ｎｄ11＝1.4875 νｄ11＝70.4
ｒ12＝-262.359 ｄ12＝ 6.62
ｒ13＝ -33.186 ｄ13＝ 5.88 ｎｄ13＝1.7707 νｄ13＝50.2
ｒ14＝ -20.195
【００３０】
【表３】
［第３実施例］
ｆ＝5mm
β＝-40×
Ｎ．Ａ．＝0.65
ｒ1 ＝ -3.075 ｄ1 ＝ 6.15 ｎｄ1 ＝1.7481 νｄ1 ＝52.3
ｒ2 ＝ -4.536 ｄ2 ＝ 0.39
ｒ3 ＝ -39.801 ｄ3 ＝ 5.79 ｎｄ3 ＝1.5186 νｄ3 ＝70.0
ｒ4 ＝ -9.512 ｄ4 ＝ 0.18
ｒ5 ＝ +20.751 ｄ5 ＝ 2.99 ｎｄ5 ＝1.4978 νｄ5 ＝82.5
ｒ6 ＝ -10.116 ｄ6 ＝ 1.02 ｎｄ6 ＝1.6716 νｄ6 ＝38.8
ｒ7 ＝ +10.116 ｄ7 ＝ 2.99 ｎｄ7 ＝1.4978 νｄ7 ＝82.5
ｒ8 ＝ -20.751 ｄ8 ＝37.20
ｒ9 ＝ +21.301 ｄ9 ＝ 3.03 ｎｄ9 ＝1.7234 νｄ9 ＝37.9
ｒ10＝+128.178 ｄ10＝ 3.93 ｎｄ10＝1.5186 νｄ10＝70.0
ｒ11＝ +12.073
【００３１】
【表４】
ｆ＝4mm
β＝-50×
Ｎ．Ａ．＝0.9
ｒ1 ＝ ∞ ｄ1 ＝ 0.64 ｎｄ1 ＝1.5168 νｄ1 ＝64.1
ｒ2 ＝ -1.0300 ｄ2 ＝ 6.22 ｎｄ2 ＝1.8404 νｄ2 ＝43.3
ｒ3 ＝ -4.941 ｄ3 ＝ 0.19
ｒ4 ＝+153.617 ｄ4 ＝ 3.19 ｎｄ4 ＝1.5186 νｄ4 ＝70.0
ｒ5 ＝ -10.484 ｄ5 ＝ 0.99
ｒ6 ＝+147.015 ｄ6 ＝ 1.49 ｎｄ6 ＝1.7950 νｄ6 ＝28.6
ｒ7 ＝ +16.261 ｄ7 ＝ 4.62 ｎｄ7 ＝1.4343 νｄ7 ＝95.0
ｒ8 ＝ -15.900 ｄ8 ＝ 0.21
ｒ9 ＝ +15.900 ｄ8 ＝ 4.62 ｎｄ9 ＝1.4343 νｄ9 ＝95.0
ｒ10＝ -16.261 ｄ10＝ 1.49 ｎｄ10＝1.7950 νｄ10＝28.6
ｒ11＝-147.015 ｄ11＝24.98
ｒ12＝ +24.560 ｄ12＝ 3.52 ｎｄ12＝1.6727 νｄ12＝32.2
ｒ13＝ -13.504 ｄ13＝ 1.97 ｎｄ13＝1.5268 νｄ13＝51.4
ｒ14＝ +9.250
以下の表５に上記各実施例の条件対応値を掲げる。
【００３２】
【表５】
【００３３】
【表６】
ｒ1 ＝ +75.045 ｄ1 ＝ 5.1 ｎｄ1 ＝1.6228 νｄ1 ＝57.0
ｒ2 ＝ -75.045 ｄ2 ＝ 2.0 ｎｄ2 ＝1.7495 νｄ2 ＝35.2
ｒ3 ＝+1600.580 ｄ3 ＝ 7.5
ｒ4 ＝ +50.256 ｄ4 ＝ 5.1 ｎｄ4 ＝1.6676 νｄ4 ＝42.0
ｒ5 ＝ -84.541 ｄ5 ＝ 1.8 ｎｄ5 ＝1.6127 νｄ5 ＝44.4
ｒ6 ＝ +36.911
なお、図５および図６に示す第１および第２実施例の諸収差図においては、軸上厚0.17、ｄ線に対する屈折率ｎｄ＝1.522、ｄ線に対するアッベ数νｄ＝58.8であるカバーガラスを物体面の表面に配置した状態での収差を示している。図８の第４実施例の諸収差図においては、液浸系であり、軸上厚0.17、ｄ線に対する屈折率ｎｄ＝1.522、ｄ線に対するアッベ数νｄ＝58.8であるカバーガラスを物体面の表面に配置し、ｄ線に対する屈折率ｎｄ＝1.5154、ｄ線に対するアッベ数νｄ＝41.4である液体を物体面と最物体側レンズ面との間に介在させた状態での収差を示している。
【００３４】
また、図５〜図８に示す諸収差図においては、表１〜表４の顕微鏡用対物レンズと表６の第２対物レンズとの間隔が１４０ｍｍである場合を示している。なお、表１〜表４の顕微鏡用対物レンズと表６の第２対物レンズとの間隔は８０乃至２００ｍｍの間であれば何れの位置でも良い。
図５〜図８の諸収差図において、ＮＡは物体側開口数、Ｙは像高、ｄはｄ線（λ＝５８７．６ｎｍ）、ＦはＦ線（λ＝４８６．１ｎｍ）、ＣはＣ線（λ＝６５６．３ｎｍ）、ｇはｇ線（λ＝４３５．８ｎｍ）、Ｓはサジタル像面、Ｍはメリジオナル像面をそれぞれ表している。
【００３５】
このように、各実施例の顕微鏡用対物レンズは、第１の正レンズ素子及び第２の正レンズ素子を共通のレンズ素子としてコスト低減を図っているにもかかわらず、良好な結像性能を達成していることがわかる。
【００３６】
【発明の効果】
以上の通り、本発明の顕微鏡対物レンズでは、良好な結像性能を維持しつつ大幅なコストダウンを図ることが可能である。
【図面の簡単な説明】
【図１】本発明の第１実施例による顕微鏡用対物レンズのレンズ構成図である。
【図２】本発明の第２実施例による顕微鏡用対物レンズのレンズ構成図である。
【図３】本発明の第３実施例による顕微鏡用対物レンズのレンズ構成図である。
【図４】本発明の第４実施例による顕微鏡用対物レンズのレンズ構成図である。
【図５】第１実施例の顕微鏡用対物レンズの諸収差図である。
【図６】第２実施例の顕微鏡用対物レンズの諸収差図である。
【図７】第３実施例の顕微鏡用対物レンズの諸収差図である。
【図８】第４実施例の顕微鏡用対物レンズの諸収差図である。
【符号の説明】
Ｇ１：第１レンズ群、
Ｇ２：第２レンズ群、
Ｇ３：第３レンズ群、[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an objective lens used in a microscope. In particular, the present invention relates to an objective lens for an achromat grade or semi-apochromat grade microscope having a flat image surface of medium to high magnification (about 10 times or more).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a medium-to-high magnification achromat-class objective lens, a Lister type is known for medium magnification and an Amici type is used for high magnification.
As a lens that improves the flatness (plan) of the image plane over these objective lenses, lens types such as triplet type, Ernostar type, and Gauss type are used at medium magnification. , A positive aplanatic lens with a strong concave surface facing the object side is located closest to the object side, and a thick meniscus lens with a concave surface facing the image side is located closest to the image side. There is known a type in which a lens is disposed on the most object side and two thick meniscus lens groups having concave surfaces facing each other are disposed on the most image side.
[0003]
[Problems to be solved by the invention]
Here, in the conventional microscope objective lens as described above, since the optical performance is emphasized, the curvature radius, the lens center thickness, and the glass material of each lens element constituting the objective lens are different from each other.
Therefore, in the production of a conventional microscope objective lens, it is necessary to process each lens element to have a different radius of curvature and a lens center thickness, and moreover, it is necessary to arrange many kinds of glass materials. The increase in cost was inevitable.
[0004]
Therefore, an object of the present invention is to provide a microscope objective lens for a medium and high magnification capable of achieving a significant cost reduction while maintaining good imaging performance.
[0005]
[Means for Solving the Problems]
To achieve the above object, a microscope objective lens according to the present invention includes, in order from the object side, a first lens group including a lens element having a concave surface directed toward the object side;
A second lens group including a first positive lens element and a second positive lens element disposed closer to the image side than the first positive lens element and having a positive refractive power as a whole;
A third lens group having negative refractive power as a whole,
The radius of curvature of the object-side lens surface of the first positive lens element is R1a, the radius of curvature of the image-side lens surface of the first positive lens element is R1b, the center thickness of the first positive lens element is D1, and the first positive lens element is The refractive index of the optical material constituting the lens element is N1, the radius of curvature of the object side lens surface of the second positive lens element is R2a, the radius of curvature of the image side lens surface of the second positive lens element is R2b, and the second When the center thickness of the positive lens element is D2, and the refractive index of the optical material constituting the second positive lens element is N2,
(1) | R1a | = | R2b |
(2) | R1b | = | R2a |
(3) D1 = D2
(4) N1 = N2
(5) | R1a |> | R1b |
(6) | R2a | <| R2b |
These conditions are satisfied.
[0006]
In the present invention, when the microscope objective lens is an infinite system, the image side refers to the side opposite to the object side with the microscope objective lens interposed therebetween.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
First, the basic configuration of the present invention will be described. The lens element having a concave surface facing the object side in the first lens group of the microscope objective lens according to the present invention minimizes spherical aberration generated in the first lens group and generates a negative Petzval sum. This contributes to improving the flatness of the image plane.
[0008]
The second lens group has a positive refractive power. In the present invention, the first and second positive lens elements in the second lens group are simultaneously subjected to the conditional expressions (1) to (6). It is configured to satisfy.
Conditional expressions (1) to (4) indicate that the two positive lenses (first and second positive lens elements) in the second lens group of the microscope objective lens of the present invention are both composed of the same lens element. Means that Therefore, when manufacturing the microscope objective lens according to the present invention, only one type of positive lens element is processed, and two lens elements among the lens elements constituting the microscope objective lens can be processed. Since the number of glass types to be used is reduced, and the curvature and center thickness of the lens can be made uniform, the number of lens processing jigs is reduced, and the total number of man-hours is reduced, thereby greatly reducing the cost.
[0009]
Conditional expressions (5) and (6) mean that the first and second positive lens elements are arranged so that the lens surfaces having a strong curvature face each other. The refractive power carried by each lens surface in is dispersed. When the conditional expressions (5) and (6) are not satisfied, it is difficult to correct spherical aberration and coma aberration generated from the first lens group and the second lens group.
[0010]
The third lens group has negative refracting power as a whole, thereby contributing to an improvement in image flatness together with a concave surface directed toward the object side in the first lens group. In the microscope objective lens according to the present invention, the Abbe number of the first positive lens element in the second lens group is νd1, and the Abbe number of the second positive lens element in the second lens group is νd2. In this case, it is preferable that the following conditional expressions (7) and (8) are satisfied.
(7) νd1 ≧ 62
(8) νd2 ≧ 62
These conditional expressions (7) and (8) are for suppressing axial chromatic aberration and lateral chromatic aberration generated in the first lens group and the second lens group. These conditional expressions (7) and (8) When the value is below the lower limit, the axial chromatic aberration and the lateral chromatic aberration of the entire microscope objective lens system are insufficiently corrected.
[0011]
In the microscope objective lens according to the present invention, the converted tilt angle of the paraxial ray incident on the object side lens surface of the first positive lens element is αin, and the near angle incident on the object side lens surface of the first positive lens element. The incident height of the axial ray is hin, the converted inclination angle of the paraxial ray emitted from the image side lens surface of the second positive lens element is αout, and the paraxial ray emitted from the image side lens surface of the second positive lens element Where hout is the incident height and hinc is the incident height of the paraxial ray emitted from the third lens group,
(9) −1 <αout / αin <−0.15
(10) | Hin / Hend |> 1
(11) | hout / hend |> 1
It is preferable to be configured to satisfy these conditions.
[0012]
The definition of the conversion tilt angle is described in “Lens Design Method”, page 20 of Kyoritsu Publishing, published by Yoshiya Matsui.
Conditional expression (9) defines the lateral magnification of the lens group sandwiched between the first positive lens element and the second positive lens element in the second lens group. Here, when the value is below the lower limit of the conditional expression (9), the refractive power of the entire second lens unit becomes too strong, which is not preferable because the spherical aberration becomes significantly under. Here, if the under-spherical aberration is forcibly corrected, the curvature of each lens surface in the second lens group becomes strong, so that outward coma occurs, and short-wave spherical aberration is overcorrected. This is not preferable.
[0013]
On the other hand, if the upper limit of conditional expression (9) is exceeded, the refractive power of the entire second lens group becomes too weak, so the divergent light beam from the first lens group cannot be made sufficiently convergent, and this is not preferable. . In this case, inward coma is generated, and further, the flatness of the image surface cannot be ensured, which is not preferable.
Conditional expressions (10) and (11) are related to the refractive power arrangement of the second lens group and the third lens group, and when the conditional expressions (10) and (11) are below the lower limit of the conditional expressions (10) and (11), This is not preferable because the working distance of the objective lens is shortened and the flatness of the image plane cannot be secured.
[0014]
In the microscope objective lens according to the present invention, the converted inclination angle of the paraxial ray incident on the object side lens surface of the first positive lens element is αin, and the paraxial ray incident on the object side of the second positive lens element. When the conversion inclination angle is αmid,
(12) 0 ≦ αmid / αin <0.6
It is preferable to be configured to satisfy the above condition.
[0015]
The conditional expression (12) relates to the refractive power arrangement of the first lens group and the second lens group. When the conditional expression (12) is below the lower limit of the conditional expression (12), the refractive power of the entire second lens group is Since it becomes too strong, the curvature radius of each lens surface which comprises a 2nd lens group becomes strong. At this time, outward coma occurs, and short-wave spherical aberration is overcorrected, which is not preferable.
[0016]
On the other hand, when the upper limit of the upper limit expression (12) is exceeded, the incident height of the axial light beam emitted from the second lens group becomes too high, and it is necessary to increase the negative refractive power of the third lens group. In this case, the image surface is tilted to the positive side, an outward coma is generated, and the lateral chromatic aberration is insufficiently corrected.
In the microscope objective lens according to the present invention, the first negative lens element joined to the first positive lens element in the second lens group, and the second positive lens element in the second lens group. It is preferable to further include a second negative lens element to be joined.
[0017]
In this case, the curvature radius of the lens surface of the first negative lens element opposite to the first positive lens element is R3a, and the curvature radius of the lens surface of the first negative lens element on the first positive lens element side is R3a. R3b, the center thickness of the first negative lens element is D4, the refractive index of the optical material constituting the first negative lens element is N4, and the curvature of the lens surface on the second positive lens element side of the second negative lens element The radius is R3a, the radius of curvature of the lens surface of the second negative lens element opposite to the second positive lens element is R4b, the center thickness of the second negative lens element is D4, and the second negative lens element is configured. When the refractive index of the optical material is N4,
(13) | R3a | = | R4b |
(14) | R3b | = | R4a |
(15) D3 = D4
(16) N3 = N4
It is preferable to configure so as to satisfy each of the conditions.
[0018]
In these conditional expressions (13) to (16), two lens elements (third and second negative lens elements) joined to the first and second positive lens elements in the second lens group are both It means that they are composed of the same lens element. According to this configuration, the number of glass types to be used is further reduced, and the lens curvature and center thickness can be made uniform, so that the number of lens processing jigs is reduced, and the overall man-hours are also reduced. There is an advantage that can be.
[0019]
Here, in the case of having a first negative lens element joined to the first positive lens element and a second negative lens element joined to the second positive lens element, the first negative lens element Αin is the converted tilt angle of the paraxial ray incident on the object side lens surface, and h is the incident height of the paraxial ray incident on the object side lens surface of the first negative lens element, and the image side lens of the second negative lens element The conversion tilt angle of the paraxial ray emitted from the surface is αout, the incident height of the paraxial ray emitted from the image side lens surface of the second negative lens element is hout, and the paraxial ray emitted from the third lens group is When the incident height is hend,
(17) −1 <αout / αin <−0.15
(18) | Hin / Hend |> 1
(19) | hout / hend |> 1
It is preferable to be configured to satisfy these conditions.
[0020]
Conditional expression (17) defines the lateral magnification of the lens group sandwiched between the first negative lens element and the second negative lens element in the second lens group. Here, if the lower limit of conditional expression (17) is not reached, the refractive power of the entire second lens unit becomes too strong, so that the spherical aberration becomes significantly under, which is not preferable. Here, if the under-spherical aberration is forcibly corrected, the curvature of each lens surface in the second lens group becomes strong, so that outward coma occurs, and short-wave spherical aberration is overcorrected. This is not preferable.
[0021]
On the other hand, if the upper limit of conditional expression (17) is exceeded, the refractive power of the entire second lens group becomes too weak, and therefore the divergent light beam from the first lens group cannot be made sufficiently convergent, and this is not preferable. . In this case, inward coma is generated, and further, the flatness of the image surface cannot be ensured, which is not preferable.
Conditional expressions (18) and (19) are related to the refractive power arrangement of the second lens group and the third lens group, and when the conditional expressions (18) and (19) are below the lower limit of the conditional expressions (18) and (19), This is not preferable because the working distance of the objective lens is shortened and the flatness of the image plane cannot be secured.
[0022]
Further, in the case of having the first negative lens element joined to the first positive lens element and the second negative lens element joined to the second positive lens element, the first negative lens element When the converted tilt angle of the paraxial ray incident on the object side lens surface is αin, and the converted tilt angle of the paraxial ray incident on the object side of the second negative lens element is αmid,
(20) 0 ≦ αmid / αin <0.6
It is preferable to be configured to satisfy the above condition.
[0023]
The conditional expression (20) relates to the refractive power arrangement of the first lens group and the second lens group. When the conditional expression (20) is below the lower limit of the conditional expression (20), the refractive power of the entire second lens group is Since it becomes too strong, the curvature radius of each lens surface which comprises a 2nd lens group becomes strong. In this case, outward coma is generated, and spherical aberration of a short wavelength is excessively corrected, which is not preferable.
[0024]
On the other hand, when the upper limit of conditional expression (20) is exceeded, the incident height of the axial light beam emitted from the second lens group becomes too high, and it is necessary to increase the negative refractive power of the third lens group. In this case, the image surface is tilted to the positive side, an outward coma is generated, and the lateral chromatic aberration is insufficiently corrected.
In the objective lens for a microscope according to the present invention, the negative lens element disposed between the first positive lens element and the second positive lens element and joined to the first and second positive lens elements is provided. Furthermore, it is preferable that it is comprised so that it may have. In this case, the negative lens element sandwiched between the first and second positive lens elements also has an advantage that the processing is easy because the lens surfaces on both sides thereof have the same curvature radius.
[0025]
The two positive lenses or the two negative lenses having the same glass type, the same radius of curvature, and the same center thickness as used in the present invention are a refractive index distribution type lens or an aspherical lens. Is not to be excluded. For example, in the case of an aspheric lens, the two lenses need only have the same aspheric shape, and in the case of a gradient index lens, the refractive index distribution in the two lenses may be the same.
[0026]
【Example】
Embodiments of a microscope objective lens according to the present invention will be described below with reference to the drawings. 1 to 4 are lens configuration diagrams of microscope objective lenses according to first to fourth embodiments, respectively.
[First embodiment]
In FIG. 1, the objective lens for a microscope according to the first embodiment is a cemented lens including, in order from the object side, a biconcave negative lens L11 having a concave surface directed toward the object side, and a positive lens L12 cemented to the negative lens L11. The first lens group G1 having a component and negative refractive power as a whole, a biconvex positive lens (first positive lens element) L21 having a strong convex surface facing the image side, and a strong convex surface facing the object side The second lens group G2 includes a biconvex positive lens (second positive lens element) L22, and the third lens group G3 includes a negative meniscus lens L31 having a concave surface directed toward the image side.
[Second Embodiment]
In FIG. 2, the objective lens for a microscope according to the second example is a cemented lens including, in order from the object side, a biconcave negative lens L11 having a concave surface directed toward the object side, and a positive lens L12 cemented to the negative lens L11. A first lens group G1 having a component and positive refracting power as a whole, a biconvex positive lens (first positive lens element) L21 having a strong convex surface facing the image side, and a strong convex surface facing the object side The second lens group G2 having a biconvex positive lens (second positive lens element) L22, a biconvex positive lens L31 having a strong convex surface facing the object side, and the positive lens L31. A cemented lens component composed of a biconcave negative lens L32 having a strong concave surface facing the image side, a negative meniscus lens L33 having a concave surface facing the object side, and a positive meniscus lens L34 having a concave surface facing the object side. Whole To composed of a third lens unit having a negative refractive power.
[Third embodiment]
In FIG. 3, the microscope objective lens according to the third embodiment includes, in order from the object side, a positive meniscus lens L11 having a concave surface facing the object side and a positive meniscus lens L12 having a concave surface facing the object side as a whole. A first lens group G1 having positive refractive power, a biconvex positive lens (first positive lens element) L21 having a strong convex surface facing the image side, a biconcave negative lens element L22, and an object side. A second lens group G2 which includes a biconvex positive lens L23 (second positive lens element) L23 having a convex surface and has a cemented lens component having a positive refractive power as a whole, and a positive meniscus lens having a concave surface facing the image side The third lens group G3 includes a negative meniscus lens L32 having a concave surface facing the image side and a cemented lens component having a negative refractive power as a whole.
[Fourth embodiment]
In FIG. 4, the objective lens for a microscope according to the fourth example includes, in order from the object side, a cemented lens component including a plano-convex lens L11 having a convex surface facing the image side and a negative meniscus lens L12 having a concave surface facing the object side, and an image. A first lens group G1 having a biconvex positive lens L13 with a strong convex surface facing the side and having positive refractive power as a whole, and a meniscus negative lens (first negative lens with a strong concave surface facing the image side) A cemented lens component consisting of a lens element) L21 and a biconvex positive lens (first positive lens element) L22 which is cemented to the negative lens L21 and has a strong convex surface facing the image side, and a strong convex surface on the object side. A cemented lens component including a positive biconvex positive lens (second positive lens element) L23 and a meniscus negative lens L24 which is cemented to the positive lens L23 and has a strong concave surface facing the object side; The cemented lens includes a second lens group G2 having positive refractive power as a whole, a biconvex positive lens L31 having a strong convex surface facing the image side, and a biconcave negative lens L32 cemented to the positive lens L31. The third lens unit G3 has a component and has a negative refractive power as a whole.
Next, the data of each said Example is shown to the following Tables 1-4.
[0027]
In Tables 1 to 4, f is a focal length, β is a lateral magnification when combined with a second objective lens described later, and N.P. A. Is the numerical aperture on the object side. In each table, ri is the radius of curvature of the i-th surface, di is the surface interval between the i-th surface and the i + 1-th surface, and ndi is the d-line (λ of the medium between the i-th surface and the i + 1-th surface) = 587.6 nm) and the refractive index (blank indicates that the medium is air), and νdi is the Abbe number for the d-line (λ = 587.6 nm) of the medium between the i-th surface and the i + 1-th surface. (The blank indicates that the medium is air).
[0028]
[Table 1]
[First embodiment]
f = 20mm
β = -10 ×
N. A. = 0.25
r1 = -12.264 d1 = 8.96 nd1 = 1.6889 νd1 = 31.1
r2 = +44.184 d2 = 5.33 nd2 = 1.4978 νd2 = 82.5
r3 = -14.935 d3 = 1.01
r4 = + 88.709 d4 = 2.97 nd4 = 1.5186 νd4 = 70.0
r5 = -37.364 d5 = 0.53
r6 = +37.364 d6 = 2.97 nd6 = 1.5186 νd6 = 70.0
r7 = -88.709 d7 = 23.35
r8 = + 31.604 d8 = 5.66 nd8 = 1.5474 νd8 = 53.5
r9 = +16.385
[0029]
[Table 2]
[Second Embodiment]
f = 20mm
β = -10 ×
N. A. = 0.30
r1 = -39.564 d1 = 8.07 nd1 = 1.6200 νd1 = 36.3
r2 = +76.081 d2 = 5.95 nd2 = 1.4339 νd2 = 95.2
r3 = -18.154 d3 = 0.16
r4 = + 104.670 d4 = 3.04 nd4 = 1.4978 νd4 = 82.5
r5 = -27.454 d5 = 0.17
r6 = +27.454 d6 = 3.04 nd6 = 1.4978 νd6 = 82.5
r7 = -104.670 d7 = 0.18
r8 = + 18.038 d8 = 7.32 nd8 = 1.5186 νd8 = 70.0
r9 = -76.185 d9 = 5.08 nd9 = 1.6200 νd9 = 36.3
r10 = +9.336 d10 = 2.89
r11 = -12.251 d11 = 1.03 nd11 = 1.4875 νd11 = 70.4
r12 = -262.359 d12 = 6.62
r13 = −33.186 d13 = 5.88 nd13 = 1.7707 νd13 = 50.2
r14 = -20.195
[0030]
[Table 3]
[Third embodiment]
f = 5mm
β = -40 ×
N. A. = 0.65
r1 = -3.075 d1 = 6.15 nd1 = 1.7481 νd1 = 52.3
r2 = -4.536 d2 = 0.39
r3 = -39.801 d3 = 5.79 nd3 = 1.5186 νd3 = 70.0
r4 = -9.512 d4 = 0.18
r5 = +20.751 d5 = 2.99 nd5 = 1.4978 νd5 = 82.5
r6 = -10.116 d6 = 1.02 nd6 = 1.6716 νd6 = 38.8
r7 = +10.116 d7 = 2.99 nd7 = 1.4978 νd7 = 82.5
r8 = -20.751 d8 = 37.20
r9 = +21.301 d9 = 3.03 nd9 = 1.7234 νd9 = 37.9
r10 = + 128.178 d10 = 3.93 nd10 = 1.5186 νd10 = 70.0
r11 = +12.073
[0031]
[Table 4]
f = 4mm
β = -50 ×
N. A. = 0.9
r1 = ∞ d1 = 0.64 nd1 = 1.5168 νd1 = 64.1
r2 = -1.0300 d2 = 6.22 nd2 = 1.8404 νd2 = 43.3
r3 = -4.941 d3 = 0.19
r4 = + 153.617 d4 = 3.19 nd4 = 1.5186 νd4 = 70.0
r5 = -10.484 d5 = 0.99
r6 = + 147.015 d6 = 1.49 nd6 = 1.7950 νd6 = 28.6
r7 = +16.261 d7 = 4.62 nd7 = 1.4343 νd7 = 95.0
r8 = -15.900 d8 = 0.21
r9 = +15.900 d8 = 4.62 nd9 = 1.4343 νd9 = 95.0
r10 = -16.261 d10 = 1.49 nd10 = 1.7950 νd10 = 28.6
r11 = -147.015 d11 = 24.98
r12 = +24.560 d12 = 3.52 nd12 = 1.6727 νd12 = 32.2
r13 = -13.504 d13 = 1.97 nd13 = 1.5268 νd13 = 51.4
r14 = +9.250
Table 5 below lists the condition-corresponding values for each of the above examples.
[0032]
[Table 5]
[0033]
[Table 6]
r1 = +75.045 d1 = 5.1 nd1 = 1.6228 νd1 = 57.0
r2 = -75.045 d2 = 2.0 nd2 = 1.7495 νd2 = 35.2
r3 = + 1600.580 d3 = 7.5
r4 = +50.256 d4 = 5.1 nd4 = 1.6676 νd4 = 42.0
r5 = -84.541 d5 = 1.8 nd5 = 1.6127 νd5 = 44.4
r6 = +36.911
In the aberration diagrams of the first and second examples shown in FIGS. 5 and 6, a cover glass having an axial thickness of 0.17, a refractive index nd = 1.522 for the d-line, and an Abbe number νd = 58.8 for the d-line is used. The aberration in the state arrange | positioned on the surface of an object surface is shown. In the various aberration diagrams of the fourth example of FIG. 8, a cover glass having an immersion system and having an axial thickness of 0.17, a refractive index nd = 1.522 for the d-line, and an Abbe number νd = 58.8 for the d-line is shown on the object surface. The aberration is shown in a state where a liquid is disposed on the surface and has a refractive index nd = 1.5154 with respect to the d-line and an Abbe number νd = 41.4 with respect to the d-line between the object surface and the most object side lens surface.
[0034]
In addition, in the various aberration diagrams shown in FIGS. 5 to 8, the interval between the microscope objective lens in Tables 1 to 4 and the second objective lens in Table 6 is 140 mm. The distance between the microscope objective lens in Tables 1 to 4 and the second objective lens in Table 6 may be any position as long as it is between 80 and 200 mm.
5 to 8, NA is the object-side numerical aperture, Y is the image height, d is the d-line (λ = 587.6 nm), F is the F-line (λ = 486.1 nm), and C is C Line (λ = 656.3 nm), g represents g line (λ = 435.8 nm), S represents a sagittal image plane, and M represents a meridional image plane.
[0035]
As described above, the microscope objective lens of each example has good imaging performance despite the fact that the first positive lens element and the second positive lens element are used as a common lens element to reduce the cost. You can see that it has been achieved.
[0036]
【The invention's effect】
As described above, the microscope objective lens of the present invention can achieve a significant cost reduction while maintaining good imaging performance.
[Brief description of the drawings]
FIG. 1 is a lens configuration diagram of a microscope objective lens according to a first example of the present invention.
FIG. 2 is a lens configuration diagram of a microscope objective lens according to a second example of the present invention.
FIG. 3 is a lens configuration diagram of a microscope objective lens according to a third example of the present invention.
FIG. 4 is a lens configuration diagram of a microscope objective lens according to a fourth example of the present invention.
FIG. 5 is a diagram illustrating various aberrations of the microscope objective lens according to the first example.
FIG. 6 is a diagram showing various aberrations of the microscope objective lens of the second example.
FIG. 7 is a diagram illustrating various aberrations of the microscope objective lens according to the third example.
FIG. 8 is a diagram illustrating various aberrations of the microscope objective lens according to the fourth example.
[Explanation of symbols]
G1: first lens group,
G2: second lens group,
G3: third lens group,
Claims (10)
第１の正レンズ素子と該第１の正レンズ素子よりも像側に配置される第２の正レンズ素子とを含み全体として正屈折力を有する第２レンズ群と、
全体として負屈折力を有する第３レンズ群とを有し、
前記第１の正レンズ素子の物体側レンズ面の曲率半径をＲ１ａ、前記第１の正レンズ素子の像側レンズ面の曲率半径をＲ１ｂ、前記第１の正レンズ素子の中心厚をＤ１、前記第１の正レンズ素子を構成する光学材料の屈折率をＮ１、前記第２の正レンズ素子の物体側レンズ面の曲率半径をＲ２ａ、前記第２の正レンズ素子の像側レンズ面の曲率半径をＲ２ｂ、前記第２の正レンズ素子の中心厚をＤ２、前記第２の正レンズ素子を構成する光学材料の屈折率をＮ２とするとき、
｜Ｒ１ａ｜＝｜Ｒ２ｂ｜
｜Ｒ１ｂ｜＝｜Ｒ２ａ｜
Ｄ１＝Ｄ２
Ｎ１＝Ｎ２
｜Ｒ１ａ｜＞｜Ｒ１ｂ｜
｜Ｒ２ａ｜＜｜Ｒ２ｂ｜
の各条件を満足することを特徴とする顕微鏡用対物レンズ。In order from the object side, a first lens group including a lens element having a concave surface directed toward the object side;
A second lens group including a first positive lens element and a second positive lens element disposed closer to the image side than the first positive lens element and having a positive refractive power as a whole;
A third lens group having negative refractive power as a whole,
The radius of curvature of the object-side lens surface of the first positive lens element is R1a, the radius of curvature of the image-side lens surface of the first positive lens element is R1b, the center thickness of the first positive lens element is D1, The refractive index of the optical material constituting the first positive lens element is N1, the radius of curvature of the object side lens surface of the second positive lens element is R2a, and the radius of curvature of the image side lens surface of the second positive lens element Is R2b, the center thickness of the second positive lens element is D2, and the refractive index of the optical material constituting the second positive lens element is N2,
| R1a | = | R2b |
| R1b | = | R2a |
D1 = D2
N1 = N2
| R1a |> | R1b |
| R2a | <| R2b |
An objective lens for a microscope characterized by satisfying each of the following conditions.
νｄ１≧６２
νｄ２≧６２2. The objective lens for a microscope according to claim 1, wherein when the Abbe number of the first positive lens element is νd1 and the Abbe number of the second positive lens element is νd2, the following condition is satisfied. .
νd1 ≧ 62
νd2 ≧ 62
−１＜αｏｕｔ／αｉｎ＜−０．１５
｜ ｈｉｎ／ ｈｅｎｄ ｜＞１
｜ ｈｏｕｔ ／ ｈｅｎｄ ｜＞１
の各条件を満足することを特徴とする請求項１または２記載の顕微鏡用対物レンズ。Αin is the converted inclination angle of the paraxial ray incident on the object side lens surface of the first positive lens element, and h is the incident height of the paraxial ray incident on the object side lens surface of the first positive lens element. Αout is the converted tilt angle of the paraxial ray emitted from the image side lens surface of the second positive lens element, hout is the incident height of the paraxial ray emitted from the image side lens surface of the second positive lens element, and When the incident height of the paraxial light beam emitted from the three lens groups is hend,
−1 <αout / αin <−0.15
| Hin / Hend |> 1
| Hout / hend |> 1
3. The microscope objective lens according to claim 1, wherein the following conditions are satisfied.
０≦αｍｉｄ／αｉｎ＜０．６
の条件を満足することを特徴とする請求項１乃至３の何れか一項記載の顕微鏡用対物レンズ。When the converted tilt angle of the paraxial ray incident on the object side lens surface of the first positive lens element is αin, and the converted tilt angle of the paraxial ray incident on the object side of the second positive lens element is αmid,
0 ≦ αmid / αin <0.6
The microscope objective lens according to claim 1, wherein the following condition is satisfied.
前記第１の負レンズ素子の前記第１の正レンズ素子とは反対側のレンズ面の曲率半径をＲ３ａ、前記第１の負レンズ素子の前記第１の正レンズ素子側のレンズ面の曲率半径をＲ３ｂ、前記第１の負レンズ素子の中心厚をＤ４、前記第１の負レンズ素子を構成する光学材料の屈折率をＮ４、前記第２の負レンズ素子の前記第２の正レンズ素子側のレンズ面の曲率半径をＲ３ａ、前記第２の負レンズ素子の前記第２の正レンズ素子とは反対側のレンズ面の曲率半径をＲ４ｂ、前記第２の負レンズ素子の中心厚をＤ４、前記第２の負レンズ素子を構成する光学材料の屈折率をＮ４とするとき、
｜Ｒ３ａ｜＝｜Ｒ４ｂ｜
｜Ｒ３ｂ｜＝｜Ｒ４ａ｜
Ｄ３＝Ｄ４
Ｎ３＝Ｎ４
の各条件を満足することを特徴とする請求項１乃至５の何れか一項記載の顕微鏡用対物レンズ。A first negative lens element joined to the first positive lens element in the second lens group; a second negative lens element joined to the second positive lens element in the second lens group; Further comprising
The radius of curvature of the lens surface of the first negative lens element opposite to the first positive lens element is R3a, and the radius of curvature of the lens surface of the first negative lens element on the first positive lens element side is R3a. R3b, the center thickness of the first negative lens element is D4, the refractive index of the optical material constituting the first negative lens element is N4, the second positive lens element side of the second negative lens element The radius of curvature of the lens surface is R3a, the radius of curvature of the lens surface of the second negative lens element opposite to the second positive lens element is R4b, and the center thickness of the second negative lens element is D4, When the refractive index of the optical material constituting the second negative lens element is N4,
| R3a | = | R4b |
| R3b | = | R4a |
D3 = D4
N3 = N4
The objective lens for a microscope according to claim 1, wherein the following conditions are satisfied.
前記第２の負レンズ素子は、前記第２の正レンズ素子の像側に配置されることを特徴とする請求項６記載の顕微鏡用対物レンズ。The first negative lens element is disposed on the object side of the first positive lens element;
The microscope objective lens according to claim 6, wherein the second negative lens element is disposed on an image side of the second positive lens element.
−１＜αｏｕｔ／αｉｎ＜−０．１５
｜ ｈｉｎ／ ｈｅｎｄ ｜＞１
｜ ｈｏｕｔ ／ ｈｅｎｄ ｜＞１
の各条件を満足することを特徴とする請求項６または７記載の顕微鏡用対物レンズ。Αin is the converted tilt angle of the paraxial ray incident on the object side lens surface of the first negative lens element, and h is the incident height of the paraxial ray incident on the object side lens surface of the first negative lens element. A conversion inclination angle of a paraxial ray emitted from the image side lens surface of the second negative lens element is αout, an incident height of the paraxial ray emitted from the image side lens surface of the second negative lens element is hout, When the incident height of the paraxial light beam emitted from the three lens groups is hend,
−1 <αout / αin <−0.15
| Hin / Hend |> 1
| Hout / hend |> 1
The microscope objective lens according to claim 6, wherein the following conditions are satisfied.
０≦αｍｉｄ／αｉｎ＜０．６
の条件を満足することを特徴とする請求項６乃至８の何れか一項記載の顕微鏡用対物レンズ。When the converted tilt angle of the paraxial ray incident on the object side lens surface of the first negative lens element is αin, and the converted tilt angle of the paraxial ray incident on the object side of the second negative lens element is αmid,
0 ≦ αmid / αin <0.6
The microscope objective lens according to claim 6, wherein the following condition is satisfied.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17615796A JP3698179B2 (en) | 1996-07-05 | 1996-07-05 | Microscope objective lens |
| CN97114096A CN1172959A (en) | 1996-07-05 | 1997-07-07 | Microscope objective |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17615796A JP3698179B2 (en) | 1996-07-05 | 1996-07-05 | Microscope objective lens |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1020204A JPH1020204A (en) | 1998-01-23 |
| JP3698179B2 true JP3698179B2 (en) | 2005-09-21 |
Family
ID=16008668
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17615796A Expired - Lifetime JP3698179B2 (en) | 1996-07-05 | 1996-07-05 | Microscope objective lens |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP3698179B2 (en) |
| CN (1) | CN1172959A (en) |
-
1996
- 1996-07-05 JP JP17615796A patent/JP3698179B2/en not_active Expired - Lifetime
-
1997
- 1997-07-07 CN CN97114096A patent/CN1172959A/en active Pending
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| Publication number | Publication date |
|---|---|
| CN1172959A (en) | 1998-02-11 |
| JPH1020204A (en) | 1998-01-23 |
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