JP3754805B2 - Zoom lens and optical apparatus using the same - Google Patents
Zoom lens and optical apparatus using the same Download PDFInfo
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- JP3754805B2 JP3754805B2 JP24531497A JP24531497A JP3754805B2 JP 3754805 B2 JP3754805 B2 JP 3754805B2 JP 24531497 A JP24531497 A JP 24531497A JP 24531497 A JP24531497 A JP 24531497A JP 3754805 B2 JP3754805 B2 JP 3754805B2
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/144—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only
- G02B15/1441—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive
- G02B15/144113—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive arranged +-++
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/144—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only
- G02B15/1441—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive
- G02B15/144105—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being positive arranged +-+-
Description
【０００１】
【発明の属する技術分野】
本発明は、銀塩カメラやデジタルカメラ、ビデオカメラに好適に用いられるズームレンズ及びそれを用いた光学機器に関するものである。
【０００２】
【従来の技術】
ホームビデオカメラ等の小型軽量化に伴い、撮像用ズームレンズの小型化にもめざましい進歩が見られる。最近では特に全長の短縮化、前玉径の小型化、光学系の構成の簡略化等に力が注がれている。
【０００３】
これらの目的を達成する一つの手段として、物体側の第１レンズ群以外のレンズ群を移動させてフォーカスを行う、所謂リアフォーカス式のズームレンズが知られている。一般に、リアフォーカス式のズームレンズは、第１レンズ群を移動させてフォーカスを行うズームレンズに比べて、第１レンズ群の有効径を小さくできるため、レンズ系全体の小型化が容易になる。
【０００４】
このようなリアフォーカス式のズームレンズとして、例えば特開昭６２−２４２１３号公報、特開昭６２−２４７３１６号公報では、物体側より順に正の第１レンズ群、負の第２レンズ群、正の第３レンズ群、正の第４レンズ群を有し、第２レンズ群を移動させて変倍を行い、第４レンズ群で変倍に伴う像面変動の補正とフォーカシングを行うズームレンズを開示している。
【０００５】
また一方では、１０倍以上の高変倍化を達成するズームレンズへのニーズが大きくなってきている。しかしながら、高変倍化を実現しつつ収差を抑えるためには、各レンズ群を構成するレンズの枚数を多くして、各レンズ群の収差補正にかかる分担を小さくする必要がある。各レンズ群を構成するレンズ枚数が増えると、当然ズームレンズ全体は大型化することになる。つまりズームレンズの高変倍化の要求は、小型化への要求とは相反するものであった。
【０００６】
この二律背反する要求を達成するため、ズームレンズを構成するレンズに非球面を用いる方法が従来より知られている。ただし、１０倍を超える高変倍比においては、色収差の補正も重要な課題となってくるが、非球面レンズでの色収差の補正は難しい。
【０００７】
ところで、色収差を良好に補正しつつ、ズームレンズを小型化する方法として、回折光学素子を用いる方法が知られている。
【０００８】
例えば米国特許５，２６８，７９０号には、バリエーターである第２レンズ群及び／またはコンペンセーターである第３レンズ群に回折光学素子を用いることを開示している。
【０００９】
【発明が解決しようとする課題】
本発明は、レンズ系の小型化を図りつつ、高変倍で、良好に色収差の補正された従来存在しない構成のズームレンズを提供することを目的とする。
【００１０】
【課題を解決するための手段】
上記目的を達成するため、本願第１発明のズームレンズは、長い共役側より順に、正の屈折力の第１レンズ群、負の屈折力の第２レンズ群、正の屈折力の第３レンズ群、正の屈折力の第４レンズ群のみをレンズ群として有し、広角端から望遠端へのズーミングに際して、前記第２レンズ群を移動させることにより像の大きさを変えるとともに、第３レンズ群以降の少なくとも１つのレンズ群を移動させることによりズーミングに伴う像面変動を補正する全体で正の屈折力のズームレンズにおいて、前記第１レンズ群が回折光学素子を有し、前記回折光学素子の位相を、
【外１６】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
とするとき、
１×１０−４＜｜Ｃ２／Ｃ１｜＜１×１０−１ （４ａ）
１×１０−７＜｜Ｃ３／Ｃ１｜＜１×１０−４ （５ａ）
なる条件を満足することを特徴としている。
また、これを５群構成としても構わない。すなわち、本願第２発明のズームレンズは、長い共役側より順に、正の屈折力の第１レンズ群、負の屈折力の第２レンズ群、正の屈折力の第３レンズ群、負の屈折力の第４レンズ群、正の屈折力の第５レンズ群のみをレンズ群として有し、広角端から望遠端へのズーミングに際して、前記第２レンズ群を移動させることにより像の大きさを変えるとともに、第３レンズ群以降の少なくとも１つのレンズ群を移動させることによりズーミングに伴う像面変動を補正する全体で正の屈折力のズームレンズにおいて、前記第１レンズ群が回折光学素子を有し、前記回折光学素子の位相を式（１）で表すとき、
１×１０ −４ ＜｜Ｃ２／Ｃ１｜＜１×１０ −１ （４ａ）
１×１０ −７ ＜｜Ｃ３／Ｃ１｜＜１×１０ −４ （５ａ）
なる条件を満足することを特徴としている。
【００１１】
本願第３発明のズームレンズは、長い共役側より順に、正の屈折力の第１レンズ群、負の屈折力の第２レンズ群、ズーミング中固定で正の屈折力の第３レンズ群、正の屈折力の第４レンズ群のみをレンズ群として有し、広角端から望遠端へのズーミングに際して、前記第２レンズ群を移動させることにより像の大きさを変えるとともに、第４レンズ群以降の少なくとも１つのレンズ群を移動させることによりズーミングに伴う像面変動を補正するズームレンズにおいて、前記第２レンズ群が回折光学素子を有し、前記回折光学素子の位相を式（１）で表すとき、
１×１０−４＜｜Ｃ２／Ｃ１｜＜１×１０＋１ （４ｂ）
１×１０−５＜｜Ｃ３／Ｃ１｜＜１×１０−３ （５ｂ）
なる条件を満足することを特徴としている。
また、これを５群構成としても構わない。すなわち、本願第４発明のズームレンズは、長い共役側より順に、正の屈折力の第１レンズ群、負の屈折力の第２レンズ群、ズーミング中固定で正の屈折力の第３レンズ群、負の屈折力の第４レンズ群、正の屈折力の第５レンズ群のみをレンズ群として有し、広角端から望遠端へのズーミングに際して、前記第２レンズ群を移動させることにより像の大きさを変えるとともに、第４レンズ群以降の少なくとも１つのレンズ群を移動させることによりズーミングに伴う像面変動を補正するズームレンズにおいて、前記第２レンズ群が回折光学素子を有し、前記回折光学素子の位相を式（１）で表すとき、
１×１０ −４ ＜｜Ｃ２／Ｃ１｜＜１×１０ ＋１ （４ｂ）
１×１０ −５ ＜｜Ｃ３／Ｃ１｜＜１×１０ −３ （５ｂ）
なる条件を満足することを特徴としている。
【００１２】
本願第５発明のズームレンズは、長い共役側より順に、少なくとも、正の屈折力の第１レンズ群、負の屈折力の第２レンズ群、ズーミング中固定で正の屈折力の第３レンズ群、正の屈折力の第４レンズ群のみをレンズ群として有し、広角端から望遠端へのズーミングに際して、前記第２レンズ群を移動させることにより像の大きさを変えるとともに、第４レンズ群以降の少なくとも１つのレンズ群を移動させることによりズーミングに伴う像面変動を補正するズームレンズにおいて、前記第３レンズ群が回折光学素子を有し、前記回折光学素子の位相を式（１）で表すとき、
１×１０−４＜｜Ｃ２／Ｃ１｜＜１×１０−１ （４ｃ）
１×１０−５＜｜Ｃ３／Ｃ１｜＜１×１０−２ （５ｃ）
なる条件を満足することを特徴としている。
また、これを５群構成としても構わない。すなわち、本願第６発明のズームレンズは、長い共役側より順に、少なくとも、正の屈折力の第１レンズ群、負の屈折力の第２レンズ群、ズーミング中固定で正の屈折力の第３レンズ群、負の屈折力の第４レンズ群、正の屈折力の第５レンズ群のみをレンズ群として有し、広角端から望遠端へのズーミングに際して、前記第２レンズ群を移動させることにより像の大きさを変えるとともに、第４レンズ群以降の少なくとも１つのレンズ群を移動させることによりズーミングに伴う像面変動を補正するズームレンズにおいて、前記第３レンズ群が回折光学素子を有し、前記回折光学素子の位相を式（１）で表すとき、
１×１０ −４ ＜｜Ｃ２／Ｃ１｜＜１×１０ −１ （４ｃ）
１×１０ −５ ＜｜Ｃ３／Ｃ１｜＜１×１０ −２ （５ｃ）
なる条件を満足することを特徴としている。
【００１４】
また、本願第１乃至第３発明のズームレンズにおいて、回折光学素子の位相を式（１）で表すとき、
Ψｉ・Ｃ１＜０ （２）
Ψｉ：回折光学素子を有するレンズ群の屈折力
なる条件を満足することが望ましい。
【００１５】
特に、回折光学素子が形成された面（ベース面）の曲率による屈折力をψｉとするとき、
ψｉ・Ｃ１＜０ （３）
なる条件を満足することが望ましい。
【００１７】
また、本願第１発明のズームレンズにおいて、第１レンズ群の焦点距離をＦ１、回折光学素子の回折光学面のみの焦点距離をＦｂｏとするとき、
０． ０５＜Ｆ１／Ｆｂｏ＜０．７ （６ａ）
なる条件を、本願第２発明のズームレンズにおいて、第２レンズ群の焦点距離をＦ２、回折光学素子の回折光学面のみの焦点距離をＦｂｏとするとき、
０． １＜｜ Ｆ２／Ｆｂｏ ｜ ＜０．７ （６ｂ）
なる条件を、本願第３発明のズームレンズにおいて、第３レンズ群の焦点距離をＦ３、回折光学素子の回折光学面のみの焦点距離をＦｂｏとするとき、
０． ０５＜Ｆ３／Ｆｂｏ＜０．２ （６ｃ）
なる条件を満足することが望ましい。
【００１８】
なお、ここでいう「回折光学面のみの焦点距離」とは、ベース面の曲率による屈折力を除いた回折光学面の回折作用だけで決まる焦点距離のことである。
【００１９】
また、本願第１発明のズームレンズにおいて、第１レンズ群の焦点距離をＦ１、広角端、望遠端での全系の焦点距離をそれぞれＦｗ、Ｆｔとするとき、
【００２０】
【外１４】
【００２１】
【外１５】
【００２２】
【外１６】
【００２３】
また、本願第１発明のズームレンズにおいて、第１レンズ群中、回折光学面が１面のみであり、第１レンズ群の焦点距離をＦ１、回折光学面のベース面の曲率をＲｂｏとするとき、
｜Ｆ１／Ｒｂｏ｜＜１．８ （８ａ）
なる条件を、本願第２発明のズームレンズにおいて、第２レンズ群中、回折光学面が１面のみであり、第２レンズ群の焦点距離をＦ２、回折光学面のベース面の曲率をＲｂｏとするとき、
｜Ｆ２／Ｒｂｏ｜＜１．８ （８ｂ）
なる条件を、本願第３発明のズームレンズにおいて、第３レンズ群中、回折光学面が１面のみであり、第３レンズ群の焦点距離をＦ３、該回折光学面のベース面の曲率をＲｂｏとするとき、
｜Ｆ３／Ｒｂｏ｜＜０．７ （８ｃ）
なる条件を満足することが望ましい。
【００２４】
また、本願第１発明のズームレンズにおいて、第１レンズ群の光軸上の厚みをｔ１、前記第１レンズ群の焦点距離をＦ１とするとき、
０．１＜ｔ１／Ｆ１＜０．２７ （９ａ）
なる条件を、本願第２発明のズームレンズにおいて、第２レンズ群の光軸上の厚みをｔ２、前記第２レンズ群の焦点距離をＦ２とするとき、
０．０５＜｜ ｔ２／Ｆ２｜ ＜０．４ （９ｂ）
なる条件を、本願第３発明のズームレンズにおいて、第３レンズ群の光軸上の厚みをｔ３、前記第３レンズ群の焦点距離をＦ３とするとき、
０．１＜ｔ３／Ｆ３＜０．２７ （９ｃ）
なる条件を満足することが望ましい。
【００２５】
【発明の実施の形態】
図１〜図８は、数値実施例１〜８に対応するズームレンズである。各図は全て広角端でのレンズ配置であり、広角端から望遠端へのレンズの移動の様子を矢印にて示している。図９〜図１６は、それぞれ図１〜図８のレンズ系に対応した広角端、望遠端における収差図である。
【００２６】
各図中、物体側（長い共役側）から順に、１は正の屈折力で固定の第１レンズ群、２は負の屈折力で変倍を行う第２レンズ群、３は正の屈折力で固定の第３レンズ群、４は正又は負の屈折力で変倍に伴う像面の補正並びにフォーカシングを行う第４レンズ群、５は正の屈折力で固定の第５レンズ群、Ｓは絞り、Ｇは光学フィルター、フェースプレート等、Ｉは像面、Ｂは回折光学面を表している。
【００２７】
図１、２、４、５、７に示したものは４群構成であり、第４レンズ群は正の屈折力を有している。図３、６に示したものは５群構成であり、第４レンズ群は負の屈折力を有している。
【００２８】
次に前述の条件式の意味について説明する。
【００２９】
式（２）において、Ｃ１は回折光学面による近軸屈折力を表している。式（２）の条件を満たすとき、回折光学素子を有するレンズ群の屈折力が正のときも、負のときも、そのレンズ群を構成する各レンズの曲率を緩くできるため、収差補正上有効である。
【００３０】
特に式（３）の条件を満たせば、同一の屈折力を持つ面を設定しても曲率が緩くなるため、色収差を含めた諸収差の発生を小さく抑えることができ、したがって、補正も非常に容易になる。
【００３１】
式（４ａ）〜（４ｃ）、（５ａ）〜（５ｃ）は、ビデオ用のズームレンズのように小さな径のズームレンズにおいて、有効に収差補正を行うための条件である。この条件式を外れると、収差補正が難しくなるだけでなく、回折光学素子を精度よく製造するのが難しくなる。
【００３２】
式（６ａ）〜（６ｃ）は若干の軸外収差、特に像面湾曲、ディストーションを補正するために、回折光学素子にパワーを与える際の条件である。式（６ａ）〜（６ｃ）を満たしていれば、回折光学素子の製作も難しくなく、収差補正も良好に行える。
【００３３】
式（７ａ）〜（７ｃ）の範囲であれば、回折光学素子の働きを有効に引き出すことができる。式（７ａ）〜（７ｃ）の下限値を逸脱すると、回折光学素子を含むレンズ群の屈折力が強すぎて色収差を補正しきれなくなり、また製作も困難になる。上限値を逸脱すると、回折光学素子を使わなくとも色収差の除去が容易になる。ただし、上限値を逸脱する場合であって、第１レンズ群が回折光学素子を有しているときは、所望の焦点距離のレンズを得るために、特に第２レンズ群の屈折力が強くなる。これによりペッツバール和が負に大きくなり、像面湾曲が補正過剰になるため適当でない。また、上限値を逸脱する場合であって、第２レンズ群が回折光学素子を有しているときは、第２レンズ群の移動量が大きくなるため、全長が大型化する。
【００３４】
回折光学面が１面だけのとき、式（８ａ）〜（８ｃ）の条件を逸脱すると、ベースの曲面で発生する収差を回折光学素子で補正しきれず、回折光学系の効果を十分に引き出せない。
【００３５】
式（９ａ）〜（９ｃ）は、回折光学素子を有効に用いられる範囲を示している。回折光学素子を用いると式（２）、（３）のところで述べたように、曲率が緩くても所望の屈折力が得られる。色収差補正のための組み合せレンズを回折光学素子によって廃止できれば、レンズ系の全長が短くなり有効に使われたことになる。
【００３６】
式（９ａ）〜（９ｃ）の上限値を逸脱すると、通常のガラスレンズでも可能な厚みであるため、回折光学素子を有効に使ったことにならない。また下限値を逸脱すると、回折による屈折力が多大に必要となり、収差の発生が大きくなる。
【００３７】
本実施形態の回折光学素子は、ホログラフィック光学素子（ＨＯＥ）の製作手法であるリソグラフィック手法で製作した、所謂バイナリーオプティックス（Binary Optics）と呼ばれる位相型の環状回折格子である。この場合更に回折効率を上げるため、格子の断面形状をキノフォームと呼ばれる鋸歯状の形状にしてもよい。またリソグラフィック手法で製作した型でモールド成型すれば、本実施形態の回折光学素子を安価に製作できる。
【００３８】
ところで、色収差係数（共立出版発行、松居吉哉著「レンズ設計法」８９ページ参照）といった観点から見ると絞りより物体側のレンズ群では、軸上色収差係数Ｌと倍率色収差係数Ｔが同一符号の面に回折光学面を配置し、絞りより像側のレンズ群では双方が逆符号の面に回折光学面を配置するのが好ましい。
【００３９】
本実施形態のように回折光学素子にバイナリーオプティックスを用いる場合、収差補正上やむを得ない場合などを除いて、最も物体側の面には回折光学素子を配置しないほうがよい。これは、数ミクロン、あるいはサブミクロンのオーダーの幅の溝で形成されたバイナリーオプティックスを、ゴミ等から守るためである。
【００４０】
以下に数値実施例を示すが、ｒｉは物体側より順に第ｉ番目のレンズ面の曲率半径、ｄｉは物体側より順に第ｉ番目のレンズ厚または空気間隔、ｎｉとνｉはそれぞれ物体側より順に第ｉ番目のレンズの屈折率とアッベ数である。
【００４１】
非球面形状は、光軸方向にＸ軸、光軸と垂直な方向にＹ軸、光の進行方向を正とし、レンズの頂点とＸ軸の交点を原点にとり、ｒをレンズ面の近軸曲率半径、Ｋ、Ａ２、Ａ３、Ａ４、Ａ５を非球面係数とするとき、
【００４２】
【外１７】
【００４３】
また、『Ｅ−０３』の表示は、『１０-3』を意味し、長さの単位は（ｍｍ）である。
【００４４】
【外１８】
【外１９】
【外２０】
【外２１】
【外２２】
【外２３】
【外２４】
【外２５】
ところで、各数値実施例において回折光学素子の格子断面形状が、図１７に示すようなキノフォーム形状をしているとする。図１７中、１０１は回折光学素子であり、１０２は基材、１０３は基材１０２の表面に紫外線硬化樹脂により形成された環状回折格子である。各数値実施例においては、基材１０２は回折光学面が形成されるベース面に相当する。図１７の回折光学素子は、波長５３０ｎｍで１次回折光の回折効率が１００％となるよう、環状回折格子１０３の格子厚ｄを設定している。
【００５３】
図１８は、図１７に示す回折光学素子の１次回折光の回折効率の波長依存特性を示している。図１８から明らかなように、設計次数での回折効率は最適化した波長５３０ｎｍから離れるに従って低下する一方、設計次数近傍の次数の０次、２次回折光の回折効率が増大する。この設計次数以外の回折光は、フレアの原因となるため光学系の解像度の低下につながる。
【００５４】
数値実施例８のズームレンズにおいて、回折光学素子の格子断面形状が図１７の格子形状である場合の、ワイド端での空間周波数に対するＭＴＦ特性を図１９に示す。この図で、低周波数領域のＭＴＦが所望の値より低下していることがわかる。
【００５５】
ここで、回折光学素子が、図２０に示すような積層型の格子断面形状である場合を考える。具体的な構成としては、基材１０２上に紫外線硬化樹脂（ｎｄ＝１．４９９、νｄ＝５４）からなる第１の回折格子１０４を形成し、その上に別の紫外線硬化樹脂（ｎｄ＝１．５９８、νｄ＝２８）からなる第２の回折格子１０５を形成している。この材質の組み合わせでは、第１の回折格子部の格子厚ｄｌはｄｌ＝１３．８μｍ、第２の回折格子部の格子厚ｄ２はｄ２＝１０．５μｍとなる。
【００５６】
図２１は、図２０に示す回折光学素子の１次回折光の回折効率の波長依存特性である。図２１からわかるように、積層構造の回折格子にすることで、設計次数の回折効率が使用波長城全域で９５％以上の高い回折効率を有している。
【００５７】
数値実施例８のズームレンズにおいて、回折光学素子の格子断面形状が図２０の格子形状である場合の、ワイド端での空間周波数に対するＭＴＦ特性を図２２に示す。積層構造の回折格子を用いることで、低周波数領域のＭＴＦは改善され、所望のＭＴＦ特性が得られる。このように、積層構造の回折格子を回折光学素子として用いることで、光学性能はさらに改善される。
【００５８】
なお前述の積層構造の回折光学素子の材質は、紫外線硬化樹脂に限定されるものではなく、他のプラスチック材なども使用できるし、基材によっては、第１の回折格子１０４を直接基材に形成してもよい。また各格子厚が必ずしも異なる必要はなく、材料の組み合わせによっては図２３に示すように２つの格子厚を等しくできる。この場合は、回折光学素子表面に格子形状が形成されないので、防塵性に優れ、回折光学素子の組み立て作業性が向上し、より安価な光学系を提供できる。
【００５９】
図２４、図２５は、本発明のズームレンズを光学機器に適用した例である。
【００６０】
図２４は本発明のズームレンズをビデオカメラに用いた場合であり、図中１０はビデオカメラ本体、１１は本発明のズームレンズによって構成される撮像光学系、１２はＣＣＤ等の撮像素子、１３は記録部である。撮像光学系１１によって取り込まれた像が撮像素子１２上に結像し、画像情報を記録部１３に記録する。不図示のファインダー系により観察者は撮影中に撮像素子上に形成された物体像を観察することができる。図２４と同様のシステムでデジタルスチルカメラも実現できる。
【００６１】
図２５は銀塩コンパクトカメラに用いた場合である。図中２０はカメラ本体、２１は本発明のズームレンズによって構成される撮影光学系、２２はフィルム面、２３はファインダー光学系である。
【００６２】
図２４、図２５に示したように、本発明のズームレンズを用いることにより、装置の小型化を図りつつ、高変倍で、良好に色収差の補正された光学機器を提供できる。
【００６３】
【発明の効果】
以上説明したように本発明によれば、レンズ系の小型化を図りつつ、高変倍で、良好に色収差の補正されたズームレンズを提供することができる。
【図面の簡単な説明】
【図１】本発明の数値実施例１のズームレンズの断面図である。
【図２】本発明の数値実施例２のズームレンズの断面図である。
【図３】本発明の数値実施例３のズームレンズの断面図である。
【図４】本発明の数値実施例４のズームレンズの断面図である。
【図５】本発明の数値実施例５のズームレンズの断面図である。
【図６】本発明の数値実施例６のズームレンズの断面図である。
【図７】本発明の数値実施例７のズームレンズの断面図である。
【図８】本発明の数値実施例８のズームレンズの断面図である。
【図９】本発明の数値実施例１のズームレンズの広角端と望遠端の収差図である。
【図１０】本発明の数値実施例２のズームレンズの広角端と望遠端の収差図である。
【図１１】本発明の数値実施例３のズームレンズの広角端と望遠端の収差図である。
【図１２】本発明の数値実施例４のズームレンズの広角端と望遠端の収差図である。
【図１３】本発明の数値実施例５のズームレンズの広角端と望遠端の収差図である。
【図１４】本発明の数値実施例６のズームレンズの広角端と望遠端の収差図である。
【図１５】本発明の数値実施例７のズームレンズの広角端と望遠端の収差図である。
【図１６】本発明の数値実施例８のズームレンズの広角端と望遠端の収差図である。
【図１７】回折光学素子の格子断面形状の一例を示す図である。
【図１８】図１７の回折光学素子の１次回折光の回折効率の波長依存特性を示す図である。
【図１９】図１７の回折光学素子を有するズームレンズの空間周波数に対するＭＴＦ特性を示す図である。
【図２０】積層構造の回折光学素子の格子断面形状の一例を示す図である。
【図２１】図２０の回折光学素子の１次回折効率の波長依存特性を示す図である。
【図２２】図２０の回折光学素子を有するズームレンズの空間周波数に対するＭＴＦ特性を示す図である。
【図２３】積層構造の回折光学素子の格子断面形状の別の例を示す図である。
【図２４】本発明のズームレンズを有したビデオカメラの要部概略図である。
【図２５】本発明のズームレンズを有したコンパクトカメラの要部概略図である。
【符号の説明】
１ 第１レンズ群
２ 第２レンズ群
３ 第３レンズ群
４ 第４レンズ群
５ 第５レンズ群
Ｓ 絞り
Ｇ 光学フィルター、フェースプレート等
Ｉ 像面
Ｂ 回折光学面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zoom lens suitably used for a silver salt camera, a digital camera, and a video camera, and an optical apparatus using the zoom lens.
[0002]
[Prior art]
With the reduction in size and weight of home video cameras and the like, remarkable progress has been made in reducing the size of imaging zoom lenses. Recently, efforts have been focused on shortening the overall length, reducing the front lens diameter, simplifying the configuration of the optical system, and the like.
[0003]
As one means for achieving these objects, a so-called rear focus type zoom lens that performs focusing by moving a lens group other than the first lens group on the object side is known. In general, a rear focus type zoom lens can reduce the effective diameter of the first lens group compared to a zoom lens that moves the first lens group to perform focusing, and thus the entire lens system can be easily downsized.
[0004]
As such a rear focus type zoom lens, for example, in Japanese Patent Application Laid-Open Nos. 62-24213 and 62-247316, a positive first lens group, a negative second lens group, A zoom lens that has a third lens group, a positive fourth lens group, performs zooming by moving the second lens group, and performs correction and focusing of image plane variation accompanying zooming by the fourth lens group. Disclosure.
[0005]
On the other hand, there is an increasing need for a zoom lens that achieves a zoom ratio of 10 times or more. However, in order to suppress aberrations while realizing high zoom ratio, it is necessary to increase the number of lenses constituting each lens group to reduce the share of aberration correction of each lens group. As the number of lenses constituting each lens group increases, the entire zoom lens naturally becomes larger. That is, the demand for high zoom magnification of the zoom lens is contrary to the demand for miniaturization.
[0006]
In order to achieve this contradictory requirement, a method of using an aspherical surface for a lens constituting a zoom lens has been conventionally known. However, at a high zoom ratio exceeding 10 times, correction of chromatic aberration is an important issue, but correction of chromatic aberration with an aspheric lens is difficult.
[0007]
Incidentally, a method using a diffractive optical element is known as a method for reducing the size of a zoom lens while correcting chromatic aberration satisfactorily.
[0008]
For example, US Pat. No. 5,268,790 discloses the use of a diffractive optical element for a second lens group that is a variator and / or a third lens group that is a compensator.
[0009]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens having a structure that does not exist in the related art, with high zoom ratio and good chromatic aberration correction, while reducing the size of the lens system.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the zoom lens according to the first aspect of the present invention includes, in order from the long conjugate side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power . And a fourth lens group having a positive refractive power as a lens group. When zooming from the wide-angle end to the telephoto end, the second lens group is moved to change the image size, and the third lens In a zoom lens having an overall positive refractive power that corrects image plane variation accompanying zooming by moving at least one lens group subsequent to the first group, the first lens group includes a diffractive optical element, and the diffractive optical element Phase of
[Outside 16]
1 × 10 −4 <| C2 / C1 | <1 × 10 −1 (4a)
1 × 10 −7 <| C3 / C1 | <1 × 10 −4 (5a)
It is characterized by satisfying the following conditions.
Further, this may be a five-group configuration. That is, the zoom lens according to the second invention of the present application, in order from the long conjugate side, is a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a negative refraction. Only the fourth lens unit having a positive power and the fifth lens unit having a positive refractive power are used as a lens unit. When zooming from the wide-angle end to the telephoto end, the size of the image is changed by moving the second lens unit. In addition, in the zoom lens having a positive refractive power as a whole, the first lens group has a diffractive optical element. The zoom lens has a positive refractive power as a whole, and corrects the image plane variation caused by zooming by moving at least one lens group after the third lens group. , When the phase of the diffractive optical element is expressed by equation (1),
1 × 10 −4 <| C2 / C1 | <1 × 10 −1 (4a)
1 × 10 −7 <| C3 / C1 | <1 × 10 −4 (5a)
It is characterized by satisfying the following conditions.
[0011]
The zoom lens according to the third aspect of the present application includes, in order from the long conjugate side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power fixed during zooming, Only the fourth lens group having a refractive power of 2 is used as a lens group, and when zooming from the wide-angle end to the telephoto end, the second lens group is moved to change the size of the image, and after the fourth lens group In a zoom lens that corrects image plane variation caused by zooming by moving at least one lens group, the second lens group includes a diffractive optical element, and the phase of the diffractive optical element is expressed by Expression (1). ,
1 × 10 −4 <| C2 / C1 | <1 × 10 +1 (4b)
1 × 10 −5 <| C3 / C1 | <1 × 10 −3 (5b)
It is characterized by satisfying the following conditions.
Further, this may be a five-group configuration. That is, the zoom lens according to the fourth aspect of the present invention includes, in order from the long conjugate side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power fixed during zooming. The fourth lens group having a negative refractive power and the fifth lens group having a positive refractive power are used as a lens group. When zooming from the wide-angle end to the telephoto end, the second lens group is moved to move the image. In the zoom lens that changes the size and corrects the image plane variation caused by zooming by moving at least one lens group after the fourth lens group, the second lens group includes a diffractive optical element, and the diffraction lens When the phase of the optical element is expressed by equation (1),
1 × 10 −4 <| C2 / C1 | <1 × 10 +1 (4b)
1 × 10 −5 <| C3 / C1 | <1 × 10 −3 (5b)
It is characterized by satisfying the following conditions.
[0012]
The zoom lens according to the fifth aspect of the present application includes, in order from the long conjugate side, at least a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power fixed during zooming. The fourth lens group has only a fourth lens group having a positive refractive power as a lens group, and changes the size of the image by moving the second lens group during zooming from the wide-angle end to the telephoto end. In a zoom lens that corrects image plane fluctuations associated with zooming by moving at least one subsequent lens group, the third lens group has a diffractive optical element, and the phase of the diffractive optical element is expressed by equation (1). When representing
1 × 10 −4 <| C2 / C1 | <1 × 10 −1 (4c)
1 × 10 −5 <| C3 / C1 | <1 × 10 −2 (5c)
It is characterized by satisfying the following conditions.
Further, this may be a five-group configuration. That is, in the zoom lens according to the sixth aspect of the present invention, in order from the long conjugate side, at least a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power fixed during zooming. By having only a lens group, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power as a lens group, the second lens group is moved during zooming from the wide-angle end to the telephoto end. In the zoom lens that changes the image size and corrects image plane variation caused by zooming by moving at least one lens group after the fourth lens group, the third lens group includes a diffractive optical element, When the phase of the diffractive optical element is represented by Formula (1),
1 × 10 −4 <| C2 / C1 | <1 × 10 −1 (4c)
1 × 10 −5 <| C3 / C1 | <1 × 10 −2 (5c)
It is characterized by satisfying the following conditions.
[0014]
In the zoom lenses according to the first to third inventions of the present application, when the phase of the diffractive optical element is expressed by Expression (1),
Ψi · C1 <0 (2)
Ψi: It is desirable to satisfy the condition of refractive power of a lens group having a diffractive optical element.
[0015]
In particular, when the refractive power due to the curvature of the surface (base surface) on which the diffractive optical element is formed is ψi,
ψi · C1 <0 (3)
It is desirable to satisfy the following conditions.
[0017]
In the zoom lens of the first invention of the present application, when the focal length of the first lens group is F1, and the focal length of only the diffractive optical surface of the diffractive optical element is Fbo,
0. 05 <F1 / Fbo <0.7 (6a)
In the zoom lens of the second invention of the present application, when the focal length of the second lens group is F2, and the focal length of only the diffractive optical surface of the diffractive optical element is Fbo,
0. 1 <| F2 / Fbo | <0.7 (6b)
In the zoom lens according to the third invention of the present application, when the focal length of the third lens unit is F3 and the focal length of only the diffractive optical surface of the diffractive optical element is Fbo,
0. 05 <F3 / Fbo <0.2 (6c)
It is desirable to satisfy the following conditions.
[0018]
Here, the “focal length of only the diffractive optical surface” is a focal length determined only by the diffractive action of the diffractive optical surface excluding the refractive power due to the curvature of the base surface.
[0019]
In the zoom lens of the first invention of the present application, when the focal length of the first lens group is F1, and the focal lengths of the entire system at the wide-angle end and the telephoto end are Fw and Ft, respectively.
[0020]
[Outside 14]
[0021]
[Outside 15]
[0022]
[Outside 16]
[0023]
In the zoom lens according to the first aspect of the present invention, there is only one diffractive optical surface in the first lens group, the focal length of the first lens group is F1, and the curvature of the base surface of the diffractive optical surface is Rbo. ,
| F1 / Rbo | <1.8 (8a)
In the zoom lens of the second invention of the present application, there is only one diffractive optical surface in the second lens group, the focal length of the second lens group is F2, and the curvature of the base surface of the diffractive optical surface is Rbo. and when,
| F2 / Rbo | <1.8 (8b)
In the zoom lens of the third invention of the present application, there is only one diffractive optical surface in the third lens group, the focal length of the third lens group is F3, and the curvature of the base surface of the diffractive optical surface is Rbo. And when
| F3 / Rbo | <0.7 (8c)
It is desirable to satisfy the following conditions.
[0024]
In the zoom lens according to the first aspect of the present invention, when the thickness of the first lens unit on the optical axis is t1, and the focal length of the first lens unit is F1,
0.1 <t1 / F1 <0.27 (9a)
In the zoom lens of the second invention of the present application, when the thickness on the optical axis of the second lens group is t2, and the focal length of the second lens group is F2,
0.05 <| t2 / F2 | <0.4 (9b)
In the zoom lens according to the third invention of the present application, when the thickness on the optical axis of the third lens unit is t3 and the focal length of the third lens unit is F3,
0.1 <t3 / F3 <0.27 (9c)
It is desirable to satisfy the following conditions.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
1 to 8 are zoom lenses corresponding to Numerical Examples 1 to 8. FIG. Each figure is a lens arrangement at the wide-angle end, and the movement of the lens from the wide-angle end to the telephoto end is indicated by an arrow. 9 to 16 are aberration diagrams at the wide-angle end and the telephoto end corresponding to the lens systems of FIGS. 1 to 8, respectively.
[0026]
In each figure, in order from the object side (long conjugate side), 1 is a first lens group that is fixed with positive refractive power, 2 is a second lens group that performs zooming with negative refractive power, and 3 is positive refractive power. 3 is a fixed third lens group, 4 is a fourth lens group that performs positive and negative refractive power to correct and focus an image plane accompanying zooming, 5 is a fifth lens group that is fixed with positive refractive power, and S is A stop, G is an optical filter, a face plate, I is an image plane, and B is a diffractive optical surface.
[0027]
1, 2, 4, 5, and 7 have a four-group configuration, and the fourth lens group has a positive refractive power. 3 and 6 have a five-group configuration, and the fourth lens group has a negative refractive power.
[0028]
Next, the meaning of the above conditional expression will be described.
[0029]
In Formula (2), C1 represents the paraxial refractive power by the diffractive optical surface. When the condition of Expression (2) is satisfied, the curvature of each lens constituting the lens group can be relaxed regardless of whether the refractive power of the lens group having the diffractive optical element is positive or negative. It is.
[0030]
In particular, if the condition of the expression (3) is satisfied, the curvature becomes gentle even when a surface having the same refractive power is set, so that the occurrence of various aberrations including chromatic aberration can be suppressed to a small level. It becomes easy.
[0031]
Expressions (4a) to (4c) and (5a) to (5c) are conditions for effectively performing aberration correction in a zoom lens having a small diameter such as a zoom lens for video. If this conditional expression is not satisfied, not only aberration correction becomes difficult, but also it becomes difficult to manufacture the diffractive optical element with high accuracy.
[0032]
Expressions (6a) to (6c) are conditions for applying power to the diffractive optical element in order to correct some off-axis aberrations, particularly field curvature and distortion. If the expressions (6a) to (6c) are satisfied, it is not difficult to manufacture a diffractive optical element, and aberration correction can be performed well.
[0033]
If it is the range of Formula (7a)-(7c), the function of a diffractive optical element can be pulled out effectively. If the lower limit value of the expressions (7a) to (7c) is deviated, the refractive power of the lens group including the diffractive optical element is too strong to correct the chromatic aberration, and the manufacture becomes difficult. When the value deviates from the upper limit, chromatic aberration can be easily removed without using a diffractive optical element. However, when the value deviates from the upper limit value and the first lens group has a diffractive optical element, the refractive power of the second lens group is particularly strong in order to obtain a lens having a desired focal length. . As a result, the Petzval sum becomes negative and the field curvature is overcorrected. Further, when the value deviates from the upper limit value and the second lens group has a diffractive optical element, the movement amount of the second lens group becomes large, so that the total length becomes large.
[0034]
When there is only one diffractive optical surface, if it deviates from the conditions of the equations (8a) to (8c), the aberration generated on the curved surface of the base cannot be corrected by the diffractive optical element, and the effect of the diffractive optical system cannot be sufficiently obtained .
[0035]
Expressions (9a) to (9c) indicate a range in which the diffractive optical element is effectively used. When a diffractive optical element is used, a desired refractive power can be obtained even when the curvature is loose, as described in the expressions (2) and (3). If the combination lens for correcting chromatic aberration can be abolished by the diffractive optical element, the total length of the lens system is shortened and it is used effectively.
[0036]
When deviating from the upper limit values of the expressions (9a) to (9c), the thickness is possible even with a normal glass lens, and thus the diffractive optical element is not effectively used. On the other hand, if the value deviates from the lower limit, a great amount of refractive power is required due to diffraction, and the generation of aberration increases.
[0037]
The diffractive optical element of the present embodiment is a phase-type annular diffraction grating called “Binary Optics” manufactured by a lithographic technique that is a manufacturing technique of a holographic optical element (HOE). In this case, in order to further increase the diffraction efficiency, the cross-sectional shape of the grating may be a sawtooth shape called a kinoform. Further, if the mold is manufactured by a mold manufactured by a lithographic technique, the diffractive optical element of this embodiment can be manufactured at low cost.
[0038]
By the way, from the viewpoint of the chromatic aberration coefficient (published by Kyoritsu Publishing Co., Ltd., Yoshiya Matsui, “Lens Design Method” on page 89), the axial chromatic aberration coefficient L and the lateral chromatic aberration coefficient T have the same sign in the lens group closer to the object than the stop. It is preferable to dispose a diffractive optical surface on the surface, and in the lens group on the image side from the stop, both diffractive optical surfaces are disposed on surfaces of opposite signs.
[0039]
When binary optics is used for the diffractive optical element as in this embodiment, it is better not to dispose the diffractive optical element on the surface closest to the object side, except in cases where correction of aberration is unavoidable. This is to protect the binary optics formed by grooves having a width on the order of several microns or submicrons from dust.
[0040]
In the following numerical examples, ri is the radius of curvature of the i-th lens surface in order from the object side, di is the i-th lens thickness or air interval in order from the object side, and ni and νi are in order from the object side. The refractive index and Abbe number of the i-th lens.
[0041]
The aspherical shape is the X axis in the optical axis direction, the Y axis in the direction perpendicular to the optical axis, the light traveling direction is positive, the intersection of the lens apex and the X axis is the origin, and r is the paraxial curvature of the lens surface. When the radius, K, A2, A3, A4, and A5 are aspherical coefficients,
[0042]
[Outside 17]
[0043]
The display of “E-03” means “10 −3 ”, and the unit of length is (mm).
[0044]
[Outside 18]
[Outside 19]
[Outside 20]
[Outside 21]
[Outside 22]
[Outside 23]
[Outside 24]
[Outside 25]
By the way, in each numerical example, it is assumed that the grating cross-sectional shape of the diffractive optical element has a kinoform shape as shown in FIG. In FIG. 17, 101 is a diffractive optical element, 102 is a base material, and 103 is an annular diffraction grating formed on the surface of the
[0053]
FIG. 18 shows the wavelength dependence characteristics of the diffraction efficiency of the first-order diffracted light of the diffractive optical element shown in FIG. As is clear from FIG. 18, the diffraction efficiency at the design order decreases with increasing distance from the optimized wavelength of 530 nm, while the diffraction efficiency of the 0th-order and second-order diffracted light near the design order increases. Diffracted light other than this design order causes flare, leading to a decrease in resolution of the optical system.
[0054]
FIG. 19 shows the MTF characteristics with respect to the spatial frequency at the wide end when the grating sectional shape of the diffractive optical element in the zoom lens of Numerical Example 8 is the grating shape shown in FIG. In this figure, it can be seen that the MTF in the low frequency region is lower than the desired value.
[0055]
Here, consider a case where the diffractive optical element has a laminated grating cross-sectional shape as shown in FIG. As a specific configuration, the
[0056]
FIG. 21 shows the wavelength dependence characteristics of the diffraction efficiency of the first-order diffracted light of the diffractive optical element shown in FIG. As can be seen from FIG. 21, by using a diffraction grating having a laminated structure, the diffraction efficiency of the designed order has a high diffraction efficiency of 95% or more over the entire wavelength range used.
[0057]
FIG. 22 shows the MTF characteristics with respect to the spatial frequency at the wide end in the zoom lens of Numerical Example 8 when the grating cross-sectional shape of the diffractive optical element is that of FIG. By using a diffraction grating having a laminated structure, the MTF in the low frequency region is improved and desired MTF characteristics are obtained. As described above, the optical performance is further improved by using the diffraction grating having the laminated structure as the diffractive optical element.
[0058]
The material of the diffractive optical element having the above-described laminated structure is not limited to the ultraviolet curable resin, and other plastic materials can be used. Depending on the base material, the
[0059]
24 and 25 show examples in which the zoom lens of the present invention is applied to an optical apparatus.
[0060]
FIG. 24 shows a case where the zoom lens of the present invention is used in a video camera. In FIG. 24, 10 is a video camera body, 11 is an imaging optical system constituted by the zoom lens of the present invention, 12 is an imaging device such as a CCD, 13 Is a recording part. An image captured by the imaging
[0061]
FIG. 25 shows a case where it is used in a silver salt compact camera. In the figure, 20 is a camera body, 21 is a photographing optical system constituted by the zoom lens of the present invention, 22 is a film surface, and 23 is a finder optical system.
[0062]
As shown in FIGS. 24 and 25, by using the zoom lens of the present invention, it is possible to provide an optical apparatus that is highly variable in magnification and excellently corrected for chromatic aberration while reducing the size of the apparatus.
[0063]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a zoom lens in which the chromatic aberration is favorably corrected with high zoom ratio while reducing the size of the lens system.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a zoom lens according to Numerical Example 1 of the present invention.
FIG. 2 is a sectional view of a zoom lens according to Numerical Example 2 of the present invention.
FIG. 3 is a sectional view of a zoom lens according to Numerical Example 3 of the present invention.
FIG. 4 is a sectional view of a zoom lens according to Numerical Example 4 of the present invention.
FIG. 5 is a sectional view of a zoom lens according to Numerical Example 5 of the present invention.
FIG. 6 is a cross-sectional view of a zoom lens according to Numerical Example 6 of the present invention.
FIG. 7 is a cross-sectional view of a zoom lens according to Numerical Example 7 of the present invention.
FIG. 8 is a cross-sectional view of a zoom lens according to Numerical Example 8 of the present invention.
FIG. 9 is an aberration diagram at the wide-angle end and a telephoto end of the zoom lens according to Numerical Example 1 of the present invention.
FIG. 10 is an aberration diagram at the wide-angle end and a telephoto end of the zoom lens according to Numerical Example 2 of the present invention.
FIG. 11 is an aberration diagram at the wide-angle end and a telephoto end of the zoom lens according to Numerical Example 3 of the present invention.
FIG. 12 is an aberration diagram at the wide-angle end and a telephoto end of the zoom lens according to Numerical Example 4 of the present invention.
FIG. 13 is an aberration diagram at the wide-angle end and a telephoto end of the zoom lens according to Numerical Example 5 of the present invention.
FIG. 14 is an aberration diagram at the wide-angle end and a telephoto end of the zoom lens according to Numerical Example 6 of the present invention.
15 is an aberration diagram at a wide-angle end and a telephoto end of a zoom lens according to Numerical Example 7 of the present invention. FIG.
FIG. 16 is an aberration diagram at the wide-angle end and a telephoto end of the zoom lens according to Numerical Example 8 of the present invention.
FIG. 17 is a diagram illustrating an example of a grating cross-sectional shape of a diffractive optical element.
18 is a diagram showing the wavelength dependence characteristics of the diffraction efficiency of the first-order diffracted light of the diffractive optical element of FIG.
FIG. 19 is a diagram showing MTF characteristics with respect to the spatial frequency of a zoom lens having the diffractive optical element of FIG. 17;
FIG. 20 is a diagram illustrating an example of a cross-sectional shape of a grating of a diffractive optical element having a laminated structure.
21 is a graph showing the wavelength dependence characteristics of the first-order diffraction efficiency of the diffractive optical element in FIG.
FIG. 22 is a diagram showing MTF characteristics with respect to the spatial frequency of a zoom lens having the diffractive optical element of FIG. 20;
FIG. 23 is a diagram showing another example of a grating cross-sectional shape of a diffractive optical element having a laminated structure.
FIG. 24 is a schematic view of a main part of a video camera having a zoom lens according to the present invention.
FIG. 25 is a schematic view of a main part of a compact camera having a zoom lens according to the present invention.
[Explanation of symbols]
DESCRIPTION OF
Claims (29)
前記第１レンズ群が回折光学素子を有し、前記回折光学素子の位相を、
【外１】
Ｃｉ：位相を表す係数
ｈ：光軸からの高さ
とするとき、
１×１０−４＜｜Ｃ２／Ｃ１｜＜１×１０−１
１×１０−７＜｜Ｃ３／Ｃ１｜＜１×１０−４
なる条件を満足することを特徴とするズームレンズ。In order from the long conjugate side, only the first lens group with positive refractive power, the second lens group with negative refractive power, the third lens group with positive refractive power, and the fourth lens group with positive refractive power are used as lens groups. In zooming from the wide-angle end to the telephoto end, the size of the image is changed by moving the second lens group, and at least one lens group after the third lens group is moved, thereby accompanying zooming . In a zoom lens with positive refractive power as a whole to correct image plane fluctuations,
The first lens group has a diffractive optical element, and the phase of the diffractive optical element is
[Outside 1]
1 × 10 −4 <| C2 / C1 | <1 × 10 −1
1 × 10 −7 <| C3 / C1 | <1 × 10 −4
A zoom lens characterized by satisfying the following conditions:
前記第１レンズ群が回折光学素子を有し、前記回折光学素子の位相を、
【外２】
Ｃｉ：位相を表す係数
ｈ：光軸からの高さ
とするとき、
１×１０ −４ ＜｜Ｃ２／Ｃ１｜＜１×１０ −１
１×１０ −７ ＜｜Ｃ３／Ｃ１｜＜１×１０ −４
なる条件を満足することを特徴とするズームレンズ。 In order from the long conjugate side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a positive refractive power. In the zooming from the wide-angle end to the telephoto end, the size of the image is changed by moving the second lens group, and at least one of the third and subsequent lens groups is provided. In a zoom lens with positive refractive power as a whole, which corrects image plane fluctuations accompanying zooming by moving the lens group,
The first lens group has a diffractive optical element, and the phase of the diffractive optical element is
[Outside 2]
Ci: Coefficient representing phase
h: Height from the optical axis
And when
1 × 10 −4 <| C2 / C1 | <1 × 10 −1
1 × 10 −7 <| C3 / C1 | <1 × 10 −4
A zoom lens characterized by satisfying the following conditions:
【外３】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
前記第１レンズ群の屈折力をΨ１とするとき、
Ψ１・Ｃ１＜０
なる条件を満足することを特徴とする請求項１乃至３いずれかに記載のズームレンズ。The phase of the diffractive optical element is
[Outside 3]
Ψ1 · C1 <0
The zoom lens according to any of claims 1 to 3, characterized by satisfying the following condition.
【外４】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
前記回折光学素子の回折光学面が形成された面の曲率による屈折力をψ１とするとき、
ψ１・Ｃ１＜０
なる条件を満足することを特徴とする請求項１乃至４いずれかに記載のズームレンズ。The phase of the diffractive optical element is
[Outside 4]
ψ1 · C1 <0
The zoom lens according to any one of claims 1 to 4, characterized by satisfying the following condition.
０．０５＜Ｆ１／Ｆｂｏ＜０．７
なる条件を満足することを特徴とする請求項１乃至５いずれかに記載のズームレンズ。When the focal length of the first lens group is F1, and the focal length of only the diffractive optical surface of the diffractive optical element is Fbo,
0.05 <F1 / Fbo <0.7
The zoom lens according to any one of claims 1 to 5, characterized by satisfying the following condition.
【外５】
[Outside 5]
｜Ｆ１／Ｒｂｏ｜＜１．８
なる条件を満足することを特徴とする請求項１乃至７いずれかに記載のズームレンズ。When there is only one diffractive optical surface in the first lens group, the focal length of the first lens group is F1, and the curvature of the surface on which the diffractive optical surface is formed is Rbo.
| F1 / Rbo | <1.8
The zoom lens according to any one of claims 1 to 7, characterized by satisfying the following condition.
０．１＜ｔ１／Ｆ１＜０．２７
なる条件を満足することを特徴とする請求項１乃至８いずれかに記載のズームレンズ。When the thickness on the optical axis of the first lens group is t1, and the focal length of the first lens group is F1,
0.1 <t1 / F1 <0.27
The zoom lens according to any one of claims 1 to 8, characterized by satisfying the following condition.
前記第２レンズ群が回折光学素子を有し、前記回折光学素子の位相を、
【外６】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
とするとき、
１×１０−４＜｜Ｃ２／Ｃ１｜＜１×１０＋１
１×１０−５＜｜Ｃ３／Ｃ１｜＜１×１０−３
なる条件を満足することを特徴とするズームレンズ。In order from the long conjugate side, only a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power fixed during zooming, and a fourth lens group having a positive refractive power only. When zooming from the wide-angle end to the telephoto end, the size of the image is changed by moving the second lens group, and at least one lens group after the fourth lens group is moved. In the zoom lens that corrects the image plane fluctuation accompanying zooming ,
The second lens group has a diffractive optical element, and the phase of the diffractive optical element is
[Outside 6]
1 × 10 −4 <| C2 / C1 | <1 × 10 +1
1 × 10 −5 <| C3 / C1 | <1 × 10 −3
A zoom lens characterized by satisfying the following conditions:
前記第２レンズ群が回折光学素子を有し、前記回折光学素子の位相を、
【外７】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
とするとき、
１×１０ −４ ＜｜Ｃ２／Ｃ１｜＜１×１０ ＋１
１×１０ −５ ＜｜Ｃ３／Ｃ１｜＜１×１０ −３
なる条件を満足することを特徴とするズームレンズ。 In order from the long conjugate side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power fixed during zooming, a fourth lens group having a negative refractive power, Only the fifth lens group having a positive refractive power is used as a lens group. When zooming from the wide-angle end to the telephoto end, the second lens group is moved to change the size of the image, and the fourth and subsequent lens groups. In a zoom lens that corrects image plane variation due to zooming by moving at least one lens group of
The second lens group has a diffractive optical element, and the phase of the diffractive optical element is
[Outside 7]
Ci: Coefficient representing phase
h : Height from the optical axis
And when
1 × 10 −4 <| C2 / C1 | <1 × 10 +1
1 × 10 −5 <| C3 / C1 | <1 × 10 −3
A zoom lens characterized by satisfying the following conditions:
【外８】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
前記第２レンズ群の屈折力をΨ２とするとき、
Ψ２・Ｃ１＜０
なる条件を満足することを特徴とする請求項１１又は１２記載のズームレンズ。The phase of the diffractive optical element is
[Outside 8]
Ψ2 · C1 <0
The zoom lens according to claim 11, wherein the following condition is satisfied.
【外９】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
前記回折光学素子の回折光学面が形成された面の曲率による屈折力をψ２とするとき、
ψ２・Ｃ１＜０
なる条件を満足することを特徴とする請求項１１乃至１３いずれかに記載のズームレンズ。The phase of the diffractive optical element is
[Outside 9]
ψ2 · C1 <0
The zoom lens according to claim 11, wherein the following condition is satisfied.
０．１＜｜Ｆ２／Ｆｂｏ｜＜０．７
なる条件を満足することを特徴とする請求項１１乃至１４いずれかに記載のズームレンズ。When the focal length of the second lens group is F2, and the focal length of the diffractive optical surface of the diffractive optical element is Fbo,
0.1 <| F2 / Fbo | <0.7
The zoom lens according to claim 11, wherein the following condition is satisfied.
【外１０】
[Outside 10]
｜Ｆ２／Ｒｂｏ｜＜１．８
なる条件を満足することを特徴とする請求項１１乃至１６いずれかに記載のズームレンズ。When there is only one diffractive optical surface in the second lens group, the focal length of the second lens group is F2, and the curvature of the surface on which the diffractive optical surface is formed is Rbo.
| F2 / Rbo | <1.8
The zoom lens according to claim 11, wherein the following condition is satisfied.
０．０５＜｜ｔ２／Ｆ２｜＜０．４
なる条件を満足することを特徴とする請求項１１乃至１７いずれかに記載のズームレンズ。When the thickness on the optical axis of the second lens group is t2, and the focal length of the second lens group is F2,
0.05 <| t2 / F2 | <0.4
The zoom lens according to claim 11, wherein the following condition is satisfied.
前記第３レンズ群が回折光学素子を有し、前記回折光学素子の位相を、
【外１１】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
とするとき、
１×１０−４＜｜Ｃ２／Ｃ１｜＜１×１０−１
１×１０−５＜｜Ｃ３／Ｃ１｜＜１×１０−２
なる条件を満足することを特徴とするズームレンズ。In order from the long conjugate side, at least a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power fixed during zooming, and a fourth lens having a positive refractive power This lens group is the only lens group. When zooming from the wide-angle end to the telephoto end, the image size is changed by moving the second lens group, and at least one lens group after the fourth lens group is moved. In the zoom lens that corrects the image plane variation accompanying zooming by
The third lens group has a diffractive optical element, and the phase of the diffractive optical element is
[Outside 11]
1 × 10 −4 <| C2 / C1 | <1 × 10 −1
1 × 10 −5 <| C3 / C1 | <1 × 10 −2
A zoom lens characterized by satisfying the following conditions:
前記第３レンズ群が回折光学素子を有し、前記回折光学素子の位相を、
【外１２】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
とするとき、
１×１０ −４ ＜｜Ｃ２／Ｃ１｜＜１×１０ −１
１×１０ −５ ＜｜Ｃ３／Ｃ１｜＜１×１０ −２
なる条件を満足することを特徴とするズームレンズ。 In order from the long conjugate side, at least a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power fixed during zooming, and a fourth lens having a negative refractive power A fifth lens group having a positive refractive power as a lens group, and changing the size of the image by moving the second lens group during zooming from the wide-angle end to the telephoto end; In a zoom lens that corrects image plane variation caused by zooming by moving at least one lens group after the group,
The third lens group has a diffractive optical element, and the phase of the diffractive optical element is
[Outside 12]
Ci: Coefficient representing phase
h : Height from the optical axis
And when
1 × 10 −4 <| C2 / C1 | <1 × 10 −1
1 × 10 −5 <| C3 / C1 | <1 × 10 −2
A zoom lens that satisfies the following conditions:
【外１３】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
前記第３レンズ群の屈折力をΨ３とするとき、
Ψ３・Ｃ１＜０
なる条件を満足することを特徴とする請求項２０又は２１記載のズームレンズ。The phase of the diffractive optical element is
[Outside 13]
Ψ3 · C1 <0
The zoom lens according to claim 20 or 21, wherein the following condition is satisfied.
【外１４】
Ｃｉ：位相を表す係数
ｈ ：光軸からの高さ
前記回折光学素子が形成された面の曲率による屈折力をψ３とするとき、
ψ３・Ｃ１＜０
なる条件を満足することを特徴とする請求項２０乃至２２いずれかに記載のズームレンズ。The phase of the diffractive optical element is
[Outside 14]
ψ3 · C1 <0
The zoom lens according to claim 20, wherein the following condition is satisfied.
０．０５＜Ｆ３／Ｆｂｏ＜０．２
なる条件を満足することを特徴とする請求項２０乃至２３いずれかに記載のズームレンズ。When the focal length of the third lens group is F3, and the focal length of only the diffractive optical surface of the diffractive optical element is Fbo,
0.05 <F3 / Fbo <0.2
The zoom lens according to claim 20, wherein the following condition is satisfied.
【外１５】
[Outside 15]
｜Ｆ３／Ｒｂｏ｜＜０．７
なる条件を満足することを特徴とする請求項２０乃至２５いずれかに記載のズームレンズ。When there is only one diffractive optical surface in the third lens group, the focal length of the third lens group is F3, and the curvature of the diffractive optical surface is Rbo,
| F3 / Rbo | <0.7
The zoom lens according to claim 20, wherein the following condition is satisfied.
０．１＜ｔ３／Ｆ３＜０．２７
なる条件を満足することを特徴とする請求項２０乃至２６いずれかに記載のズームレンズ。When the thickness on the optical axis of the third lens group is t3 and the focal length of the third lens group is F3,
0.1 <t3 / F3 <0.27
27. The zoom lens according to claim 20, wherein the following condition is satisfied.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24531497A JP3754805B2 (en) | 1996-09-19 | 1997-09-10 | Zoom lens and optical apparatus using the same |
| US09/421,367 US6606200B1 (en) | 1996-09-19 | 1999-10-19 | Zoom lens device and optical apparatus provided with the same |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8-247837 | 1996-09-19 | ||
| JP24783796 | 1996-09-19 | ||
| JP24531497A JP3754805B2 (en) | 1996-09-19 | 1997-09-10 | Zoom lens and optical apparatus using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10148757A JPH10148757A (en) | 1998-06-02 |
| JP3754805B2 true JP3754805B2 (en) | 2006-03-15 |
Family
ID=26537169
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24531497A Expired - Fee Related JP3754805B2 (en) | 1996-09-19 | 1997-09-10 | Zoom lens and optical apparatus using the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3754805B2 (en) |
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| CN105209951B (en) * | 2013-01-25 | 2017-09-22 | 柯尼卡美能达株式会社 | Zoom lens and camera device |
| JP2018180365A (en) | 2017-04-17 | 2018-11-15 | キヤノン株式会社 | Zoom lens and image capturing device having the same |
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-
1997
- 1997-09-10 JP JP24531497A patent/JP3754805B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10148757A (en) | 1998-06-02 |
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