JPH05107470A - Objective lens for endoscope - Google Patents
Objective lens for endoscopeInfo
- Publication number
- JPH05107470A JPH05107470A JP13530491A JP13530491A JPH05107470A JP H05107470 A JPH05107470 A JP H05107470A JP 13530491 A JP13530491 A JP 13530491A JP 13530491 A JP13530491 A JP 13530491A JP H05107470 A JPH05107470 A JP H05107470A
- Authority
- JP
- Japan
- Prior art keywords
- lens
- aberration
- diaphragm
- aspherical
- image
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Instruments For Viewing The Inside Of Hollow Bodies (AREA)
- Lenses (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、３枚の簡単な構成の内
視鏡の広角な対物レンズに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-angle objective lens for an endoscope having three simple structures.
【０００２】[0002]
【従来の技術】従来、内視鏡の広角な対物レンズは、特
開平２−２９３７０９号公報等に示されるように多数の
レンズを用いて構成されており、主に絞りが負のパワー
を持つ第１レンズ群と正のパワーを持つ第２レンズ群の
間に位置し、絞りの後方に接合レンズが配置されてい
る。それは、視野角が広くなるに伴って、第１レンズ群
で発生する諸収差を絞り以降に配置されているレンズ群
で良好に補正するためである。特に倍率色収差を補正す
るために上記のように接合レンズを配置している。2. Description of the Related Art Conventionally, a wide-angle objective lens of an endoscope is constructed by using a large number of lenses as disclosed in Japanese Patent Laid-Open No. 2-293709, and the diaphragm mainly has a negative power. A cemented lens is located between the first lens group and the second lens group having a positive power, and behind the diaphragm. This is because various aberrations occurring in the first lens group are favorably corrected by the lens groups arranged after the stop as the viewing angle becomes wider. In particular, the cemented lens is arranged as described above in order to correct lateral chromatic aberration.
【０００３】しかしながら、上記のような対物レンズ
は、レンズの枚数が多く構成が複雑であるために高価に
ならざるを得ない。However, the above objective lens is inevitably expensive because of the large number of lenses and the complicated structure.
【０００４】また、レンズ枚数を減らして比較的簡単な
構成にしようとすると、各レンズのパワーが相対的に増
大し、それに伴って諸収差が増大するのでこの収差を抑
えるために全長を伸ばさなければならず内視鏡において
要求されるコンパクト性を持つことが出来ない。Further, if the number of lenses is reduced and a relatively simple structure is attempted, the power of each lens increases relatively, and various aberrations increase accordingly. Therefore, the total length must be extended to suppress this aberration. Inevitably, the compactness required for endoscopes cannot be achieved.
【０００５】又絞りより後方の接合レンズを単レンズで
構成すると倍率の色収差を十分良好に補正できない。例
えば特開平２−２０８６１７号公報には、比較的広角で
簡単な構成をもつ対物レンズの発明が記載されている。
その視野角は、７０°程度であり、この光学系を用い
て、更に広角（８０°〜１４０°）な対物レンズを構成
しようとすると、収差が十分良好に補正できない。特に
特開平２−２０８６１７号公報の実施例の中に単レンズ
３枚で構成されている対物レンズがあり、この実施例
は、各レンズで発生する倍率の色収差の方向が同じであ
り、そのため色収差は厳密には補正されていない。Further, if the cemented lens behind the diaphragm is composed of a single lens, the chromatic aberration of magnification cannot be corrected sufficiently. For example, JP-A-2-208617 discloses an invention of an objective lens having a relatively wide angle and a simple structure.
The viewing angle is about 70 °, and if an attempt is made to construct an objective lens with a wider angle (80 ° to 140 °) using this optical system, the aberration cannot be corrected sufficiently. In particular, in the example of Japanese Patent Laid-Open No. 2-208617, there is an objective lens composed of three single lenses. In this example, the directions of the chromatic aberration of magnification generated in each lens are the same, and therefore the chromatic aberration is the same. Is not strictly corrected.
【０００６】[0006]
【発明が解決しようとする課題】本発明の目的は、安価
で構成が簡単であり、色収差を含めて収差が良好に補正
されている対物レンズを提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide an objective lens which is inexpensive, has a simple structure, and is well corrected for aberrations including chromatic aberrations.
【０００７】[0007]
【問題点を解決するための手段】本発明の内視鏡対物レ
ンズは、物体側より順に、負のパワーを有する第１レン
ズと正のパワーを有する第２レンズと第３レンズとの単
レンズ３枚からなり、絞りが第２レンズから像面までの
間に配置される。An endoscope objective lens of the present invention is a single lens composed of a first lens having negative power, a second lens having positive power, and a third lens in order from the object side. It consists of three lenses, and the diaphragm is arranged between the second lens and the image plane.
【０００８】上記構成のレンズ系で更に次の条件
（１），（２）を満足することが望ましい。 （１）５＞｜ｆ1 ／ｆ2 ｜＞0.03 （２）ｄ／ｆ＜５ ただし、ｆ1 ，ｆ2 は夫々第１レンズおよび第２レンズ
の焦点距離、ｆは全系の焦点距離、ｄは第２レンズと第
３レンズの間の主点間距離である。It is desirable that the lens system having the above structure further satisfies the following conditions (1) and (2). (1) 5> | f1 / f2 |> 0.03 (2) d / f <5 where f1 and f2 are the focal lengths of the first lens and the second lens, f is the focal length of the entire system, and d is the second. It is the distance between the principal points between the lens and the third lens.
【０００９】本発明の対物レンズは、前記の構成で、絞
りを第２レンズから像面までの間のいずれかに配置する
ものである。即ち後に示す実施例１，２，６のように、
絞りを第３レンズの像側の面から像面までの間に配置す
るか、実施例３〜５，７〜１２のように絞りを第２レン
ズの像側の面から第３レンズの物体側の面の間に配置し
たものである。The objective lens of the present invention has the above-mentioned configuration, and the diaphragm is arranged anywhere between the second lens and the image plane. That is, as in Examples 1, 2 and 6 described later,
The diaphragm is arranged between the image side surface of the third lens and the image surface, or as in Examples 3 to 5 and 7 to 12, the diaphragm is arranged from the image side surface of the second lens to the object side of the third lens. It is placed between the faces of.
【００１０】このように絞りを配置することにより、絞
りより物体側に正のパワーをもつレンズを少なくとも１
枚配置することになり、負のパワーをもつ第１レンズで
発生する倍率の色収差を上記の正のパワーをもつレンズ
でこの収差を補正する方向に発生させて倍率の色収差を
除去し、これによって倍率の色収差を補正するために従
来設けられていた接合レンズが不要になり、レンズ系を
簡単な構成になし得るようにした。By arranging the diaphragm in this way, at least one lens having a positive power on the object side of the diaphragm is provided.
The chromatic aberration of magnification that occurs in the first lens having negative power is generated in the direction in which this aberration is corrected by the lens having positive power described above, and the chromatic aberration of magnification is removed. The cemented lens that has been conventionally provided for correcting the chromatic aberration of magnification is no longer necessary, and the lens system can be made into a simple configuration.
【００１１】また倍率の色収差以外の諸収差も、各レン
ズのパワー配分を適切に選びながら面の向きを収差の補
正に最適な向きにして収差を良好に補正している。Further, various aberrations other than the chromatic aberration of magnification are properly corrected by properly selecting the power distribution of each lens and making the surface orientation optimal for aberration correction.
【００１２】また実施例１，２のように、第１レンズの
像側の面の曲率中心が面の像側にある曲率のきつい面で
あり、視野角が広くなるに伴ってこの面での非点収差や
コマ収差が増大する。そのため正のパワーを有する第２
レンズと第３レンズで第１レンズで発生する収差を打消
す方向の非点収差，コマ収差を発生させてレンズ系全体
でほぼ０になるようにしている。Further, as in Examples 1 and 2, the center of curvature of the image-side surface of the first lens is a surface having a strong curvature on the image side of the surface, and as the viewing angle becomes wider, Astigmatism and coma increase. Therefore, the second with positive power
The lens and the third lens generate astigmatism and coma in the direction of canceling the aberration generated in the first lens so that they are almost zero in the entire lens system.
【００１３】このとき、第２レンズは絞りから十分離れ
ているので主光線の光線高が高い。そこで第２レンズの
像側の面の曲率中心が物体側になるようにして第１レン
ズで発生する収差と逆方向に発生する収差により、非点
収差を補正している。At this time, since the second lens is sufficiently away from the stop, the ray height of the principal ray is high. Therefore, the astigmatism is corrected by the aberration generated in the direction opposite to the aberration generated in the first lens so that the center of curvature of the image side surface of the second lens is on the object side.
【００１４】また、第３レンズの像側の面の曲率中心を
面の物体側に位置せしめることによって第２レンズと共
に第１レンズの像側の面で発生するコマ収差を補正して
いる。Further, the center of curvature of the image-side surface of the third lens is positioned on the object side of the surface to correct coma aberration generated on the image-side surface of the first lens together with the second lens.
【００１５】又実施例３〜５のように、絞りを第２レン
ズと第３レンズの間に配置し、しかも実施例１，２より
も絞りが第２レンズに近い場合、第２レンズの像側の面
での第１レンズの像側の面で発生する非点収差を補正す
る作用が小さくなる。更に第３レンズは絞りの後方に位
置するので、この第３レンズで発生する非点収差は、第
１レンズでの収差の発生方向と同じ向きであるのでレン
ズ系全体の非点収差の補正が難しい。When the diaphragm is arranged between the second lens and the third lens as in Embodiments 3 to 5, and the diaphragm is closer to the second lens than in Embodiments 1 and 2, the image of the second lens is obtained. The effect of correcting astigmatism generated on the image side surface of the first lens on the side surface is reduced. Further, since the third lens is located behind the diaphragm, the astigmatism generated by this third lens is in the same direction as the direction of the aberration generated by the first lens. difficult.
【００１６】第１レンズを通過する主光線が第１レンズ
の像側の面のほぼ曲率中心に向かうように配置すること
によって第１レンズの像側の面で発生する非点収差の発
生量を抑えるようにし、第２レンズの物体側の面の曲率
中心と第３レンズの像側の面の曲率中心が夫々絞りの方
向になるようにし、しかも両面をほぼ対称に配置するこ
とによって、第２レンズの非点収差の補正効果の減少と
合わせてレンズ系全体の非点収差を良好に補正してい
る。By arranging the chief ray passing through the first lens so as to be directed substantially to the center of curvature of the image-side surface of the first lens, the amount of astigmatism generated on the image-side surface of the first lens can be reduced. By suppressing the center of curvature of the object-side surface of the second lens and the center of curvature of the image-side surface of the third lens in the direction of the diaphragm, and arranging both surfaces substantially symmetrically, The astigmatism of the entire lens system is well corrected together with the reduction of the astigmatism correction effect of the lens.
【００１７】またコマ収差の補正も、主光線が第２レン
ズの物体側の面にほぼ垂直に入射するようにその曲率を
選んで第２レンズの物体側の面で発生するコマ収差を抑
え、更に第２レンズの像側の面の曲率中心位置を適当に
調整することによってレンズ系全体のコマ収差を補正し
ている。Also in the correction of coma aberration, the curvature is selected so that the principal ray is incident on the object side surface of the second lens substantially perpendicularly, and the coma aberration generated on the object side surface of the second lens is suppressed, Further, the coma aberration of the entire lens system is corrected by appropriately adjusting the position of the center of curvature of the image side surface of the second lens.
【００１８】このとき、第３レンズは、コマ収差，非点
収差が発生しにくい形状にするために、特に像側の面を
その曲率中心が物体側に位置するようにした。このよう
にしてコマ収差の対称性が得られる。尚全体として像面
湾曲は僅かに残存する。At this time, in order to make the coma and astigmatism less likely to occur, the third lens is arranged such that the center of curvature of its surface on the image side is located on the object side. In this way, the symmetry of coma is obtained. Note that the field curvature slightly remains as a whole.
【００１９】本発明は、以上のように構成すると共に前
記の条件（１），（２）を満足するようにして発明の目
的を達成するようにした。The present invention has the above-mentioned structure and achieves the object of the invention by satisfying the above conditions (1) and (2).
【００２０】前述のような構成の本発明の内視鏡対物レ
ンズは、アフォーカルな第１レンズと第２レンズとより
なる前群と、正のパワーを有する単レンズの第３レンズ
からなる後群とにて構成されていると考えられる。した
がって、レンズ系の全長Ｌは次の式で表わされる。 Ｌ≡｜ｆ2|−｜ｆ1|＋ｄ＋｜ｆ3| ただしｆ3 は第３レンズの焦点距離である。The endoscope objective lens of the present invention having the above-described structure comprises a front group consisting of an afocal first lens and a second lens, and a rear group consisting of a single lens third lens having a positive power. It is considered to be composed of groups. Therefore, the total length L of the lens system is expressed by the following equation. L≡ | f2 | − | f1 | + d + | f3 | where f3 is the focal length of the third lens.
【００２１】いま｜ｆ1/ｆ2 ｜≡αとおくと、レンズ系
全系の焦点距離ｆは、ｆ≡α・ｆ3 と表わされるから、
レンズ系の全長Ｌは、次のように書き換えられる。 Ｌ≡｜ｆ2|−｜α・ｆ2|＋ｄ＋ｆ／｜α｜ この式からわかるように、αの値があまり小さいと、レ
ンズ系の全長をあまり短く出来ない。又αの値があまり
大であると第３レンズの焦点距離が小さくなって第３レ
ンズの収差補正作用が大きくなり過ぎて、レンズ系全体
の収差補正が難しくなる。When | f1 / f2 | ≡α is set, the focal length f of the entire lens system is expressed as f≡αf3.
The total length L of the lens system can be rewritten as follows. L≡ | f2 | − | α · f2 | + d + f / | α | As can be seen from this equation, if the value of α is too small, the total length of the lens system cannot be shortened too much. On the other hand, if the value of α is too large, the focal length of the third lens becomes small and the aberration correcting action of the third lens becomes too large, making it difficult to correct the aberration of the entire lens system.
【００２２】以上のような理由から設けられたのが条件
（１）である。The condition (1) is provided for the above reasons.
【００２３】尚絞りを絞った場合で、ＣＣＤ等の画素が
あらい場合は、条件（１）の上限は５まで許される。又
レンズ系にフィルターを多数挿入して光学特性を向上さ
せる場合、条件（１）の下限は０．０３としても、多少
コンパクト性はそこなわれるが実用上使用に耐え得る。When the aperture is narrowed down and the pixels such as CCD are large, the upper limit of the condition (1) is allowed up to 5. When a large number of filters are inserted in the lens system to improve the optical characteristics, even if the lower limit of the condition (1) is set to 0.03, the compactness is somewhat impaired, but it can be practically used.
【００２４】次に第２レンズと第３レンズの間の主点間
隔ｄを定めたのが条件（２）である。このｄの値が大に
なり上限を越えるとレンズ系の全長が長くなり好ましく
ない。Next, the condition (2) defines the principal point distance d between the second lens and the third lens. If the value of d becomes large and exceeds the upper limit, the total length of the lens system becomes long, which is not preferable.
【００２５】更に本発明の内視鏡対物レンズは、少なく
とも１面の非球面を最適な位置に配置することによって
諸収差を良好に補正するようにした。Further, in the endoscope objective lens of the present invention, various aberrations are satisfactorily corrected by disposing at least one aspherical surface at an optimum position.
【００２６】特にＦナンバーを小にして比較的明るいレ
ンズにする場合、球面収差およびコマ収差の発生が増大
するが、これを補正するためには非球面を設ける必要が
あり、この非球面が次の条件（３）を満足することが望
ましい。 （３）｜ｈc/ｈm ｜＜２ ただし、ｈc は最大光線高の軸外主光線の光線高、ｈm
は軸上マージナル光線の光線高である。In particular, when the F number is made small to make a relatively bright lens, the occurrence of spherical aberration and coma aberration increases, but in order to correct this, it is necessary to provide an aspherical surface. It is desirable to satisfy the condition (3). (3) | hc / hm | <2 where hc is the maximum ray height of the off-axis chief ray, hm
Is the height of the on-axis marginal ray.
【００２７】この条件（３）は、非球面の位置での軸上
マージナル光線の光線高に対する軸外主光線の光線高の
比を規定したもので、上記のように非球面により主とし
て球面収差とコマ収差とを補正するために必要な条件で
ある。This condition (3) defines the ratio of the ray height of the off-axis chief ray to the ray height of the axial marginal ray at the position of the aspherical surface. As described above, the aspherical surface mainly causes spherical aberration. This is a condition necessary for correcting coma aberration.
【００２８】この場合、球面収差とコマ収差とを補正す
るための非球面の形状は、非球面が凸面の場合光軸から
遠くなるほど曲率が緩くなるような形状であり、又凹面
の場合光軸から遠くなるほど曲率が強くなるような形状
である。つまり上記形状の非球面によれば、光線高の高
いところを通過する光線に対して球面レンズ系ではマイ
ナス側に大きく発生する球面収差，コマ収差を抑えるこ
とが出来る。In this case, the shape of the aspherical surface for correcting the spherical aberration and the coma aberration is such that when the aspherical surface is a convex surface, the curvature becomes gentler as the distance from the optical axis increases. The shape is such that the curvature increases as the distance from the point increases. That is, according to the aspherical surface having the above-described shape, it is possible to suppress spherical aberration and coma which largely occur in the minus side in the spherical lens system with respect to a ray passing through a high ray height.
【００２９】[0029]
【実施例】次に本発明の内視鏡対物レンズの実施例を示
す。 実施例１ ｆ＝1.000 ，Ｆ/4.290，２ω＝116 ° ｒ1 ＝∞ ｄ1 ＝0.5500 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝0.9454 ｄ2 ＝1.2300 ｒ3 ＝4.0175 ｄ3 ＝0.8600 ｎ2 ＝1.88300 ν2 ＝40.78 ｒ4 ＝-2.6882 ｄ4 ＝0.4000 ｒ5 ＝33.6773 ｄ5 ＝1.0300 ｎ3 ＝1.72916 ν3 ＝54.68 ｒ6 ＝-2.3068 ｄ6 ＝0.0200 ｒ7 ＝∞（絞り） ｄ7 ＝0.5600 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ8＝∞ ｄ8 ＝0.0300 ｒ9＝∞ ｄ9＝0.3600 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ10＝∞ ｄ10＝0.8000 ｒ11＝∞ ｄ11＝0.9400 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ12＝∞ ｜ｆ1/ｆ2 | ＝0.55 ，ｄ／ｆ＝1.16 実施例２ ｆ＝0.965 ，Ｆ/3.993，２ω＝135 ° ｒ1 ＝∞ ｄ1 ＝0.3738 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.0287 ｄ2 ＝1.0469 ｒ3 ＝4.6383 ｄ3 ＝1.0510 ｎ2 ＝1.88300 ν2 ＝40.78 ｒ4 ＝-6.1647 ｄ4 ＝0.6367 ｒ5 ＝3.2550 ｄ5 ＝0.5606 ｎ3 ＝1.72916 ν3 ＝54.68 ｒ6 ＝-2.2529 ｄ6 ＝0.0184 ｒ7 ＝∞（絞り） ｄ7 ＝0.6181 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ8 ＝∞ ｄ8 ＝0.0280 ｒ9＝∞ ｄ9 ＝0.3988 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ10＝∞ ｄ10＝0.7774 ｒ11＝∞ ｄ11＝0.9970 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ12＝∞ ｜ｆ1/ｆ2 |＝0.371 ，ｄ／ｆ＝1.19 実施例３ ｆ＝1.000 ，Ｆ/4.300，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.3284 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.0635 ｄ2 ＝0.8128 ｒ3 ＝1.7391 ｄ3 ＝0.8210 ｎ2 ＝1.88300 ν2 ＝40.78 ｒ4 ＝-7.8275 ｄ4 ＝0.4105 ｒ5 ＝∞（絞り） ｄ5 ＝0.0246 ｒ6 ＝6.2260 ｄ6 ＝0.5114 ｎ3 ＝1.72916 ν3 ＝54.68 ｒ7 ＝-1.7509 ｄ7 ＝0.0162 ｒ８＝∞ ｄ8＝0.5090 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ９＝∞ ｄ9＝0.0246 ｒ10＝∞ ｄ10＝0.3284 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ11＝∞ ｄ11＝0.3801 ｒ12＝∞ ｄ12＝0.8210 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ13＝∞ ｜ｆ1/ｆ2 |＝0.717 ，ｄ／ｆ＝1.04 実施例４ ｆ＝1.001 ，Ｆ/3.833，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.4984 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.2048 ｄ2 ＝0.5708 ｒ3 ＝∞ ｄ3 ＝0.6431 ｎ2 ＝1.51633 ν2 ＝64.15 ｒ4 ＝∞ ｄ4 ＝0.0322 ｒ5 ＝1.3000 ｄ5 ＝0.7464 ｎ3 ＝1.51728 ν3 ＝69.56 ｒ6 ＝-3.0866 ｄ6 ＝0.2912 ｒ7 ＝∞（絞り） ｄ7 ＝0.9419 ｎ4 ＝1.51728 ν4 ＝69.56 ｒ8 ＝-1.0736 ｄ8 ＝0.5266 ｒ9＝∞ ｄ9＝1.6077 ｎ5 ＝1.51633 ν5 ＝64.15 ｒ10＝∞ ｜ｆ1/ｆ2 |＝0.727 ，ｄ／ｆ＝1.28 実施例５ ｆ＝1.000 ，Ｆ/4.243，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.3320 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.0944 ｄ2 ＝0.8216 ｒ3 ＝1.4850 ｄ3 ＝0.8299 ｎ2 ＝1.83400 ν2 ＝37.16 ｒ4 ＝-4.8373 ｄ4 ＝0.3734 ｒ5 ＝∞（絞り） ｄ5 ＝0.1826 ｒ6 ＝11.1197 ｄ6 ＝0.5228 ｎ3 ＝1.81600 ν3 ＝46.62 ｒ7 ＝-2.0380 ｄ7 ＝0.0166 ｒ8 ＝∞ ｄ8 ＝0.5145 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ9 ＝∞ ｄ9 ＝0.0249 ｒ10＝∞ ｄ10＝0.3320 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ11＝∞ ｄ11＝0.1411 ｒ12＝∞ ｄ12＝0.8299 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ13＝∞ ｜ｆ1/ｆ2 |＝0.855 ，ｄ／ｆ＝1.17 実施例６ ｆ＝1.001 ，Ｆ/2.796，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.5000 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝0.9742 ｄ2 ＝1.1200 ｒ3 ＝1.3171 ｄ3 ＝0.7000 ｎ2 ＝1.88300 ν2 ＝40.78 ｒ4 ＝3.3918 ｄ4 ＝0.2400 ｒ5 ＝5.4887（非球面） ｄ5 ＝0.4900 ｎ3 ＝1.75500 ν3 ＝52.33 ｒ6 ＝-1.7388 ｄ6 ＝0.0200 ｒ7 ＝∞（絞り） ｄ7 ＝0.5000 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ8＝∞ ｄ8 ＝0.0200 ｒ9＝∞ ｄ9＝0.3300 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ10＝∞ ｄ10＝0.7500 ｒ11＝∞ ｄ11＝0.8200 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ12＝∞ 非球面係数 Ｐ＝1.0000，Ｅ＝-0.22281，Ｆ＝-0.12062×10-1，Ｇ＝
-0.54320×10-1 ｜ｆ1/ｆ2 |＝0.52 ，ｄ／ｆ＝0.036 ，｜ｈc/ｈm ｜
＝0.37 実施例７ ｆ＝1.000 ，Ｆ/2.536，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.3234 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝0.9210 ｄ2 ＝0.8003 ｒ3 ＝1.2745 ｄ3 ＝0.8084 ｎ2 ＝1.80518 ν2 ＝25.43 ｒ4 ＝7.4446 ｄ4 ＝0.4042 ｒ5 ＝∞（絞り） ｄ5 ＝0.0243 ｒ6 ＝1.2714 ｄ6 ＝0.5012 ｎ3 ＝1.77250 ν3 ＝49.66 ｒ7 ＝91.2505 （非球面）ｄ7 ＝0.1617 ｒ8 ＝∞ ｄ8 ＝0.5012 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ9 ＝∞ ｄ9 ＝0.0243 ｒ10＝∞ ｄ10＝0.3234 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ11＝∞ ｄ11＝0.2183 ｒ12＝∞ ｄ12＝0.8084 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ13＝∞ 非球面係数 Ｐ＝1.0000，Ｅ＝0.28326 ｜ｆ1/ｆ2 |＝0.58 ，ｄ／ｆ＝1.05 ，｜ｈc/ｈm ｜
＝0.48 実施例８ ｆ＝1.000 ，Ｆ/2.808，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.3167 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝0.9520 ｄ2 ＝0.7852 ｒ3 ＝1.3451 ｄ3 ＝0.8320 ｎ2 ＝1.88300 ν2 ＝40.78 ｒ4 ＝8.2060（非球面） ｄ4 ＝0.4819 ｒ5 ＝∞（絞り） ｄ5 ＝0.0238 ｒ6 ＝1.8507（非球面） ｄ6 ＝0.4933 ｎ3 ＝1.72916 ν3 ＝54.68 ｒ7 ＝-3.1601 ｄ7 ＝0.0156 ｒ8 ＝∞ ｄ8 ＝0.4909 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ9 ＝∞ ｄ9 ＝0.0238 ｒ10＝∞ ｄ10＝0.3167 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ11＝∞ ｄ11＝0.8234 ｒ12＝∞ ｄ12＝0.7918 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ13＝∞ 非球面係数 （第４面）Ｐ＝1.0000，Ｅ＝0.53786 ×10-2 （第６面）Ｐ＝1.0000，Ｅ＝-0.12945 ｜ｆ1/ｆ2 |＝0.626 ，ｄ／ｆ＝1.12 ，｜ｈc/ｈm ｜
＝0.82 ，0.04 実施例９ ｆ＝1.000 ，Ｆ/2.743，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.3276 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝0.8369 ｄ2 ＝0.8190 ｒ3 ＝1.1527 ｄ3 ＝0.8190 ｎ2 ＝1.80100 ν2 ＝34.97 ｒ4 ＝-6.3773 （非球面）ｄ4 ＝0.1556 ｒ5 ＝∞（絞り） ｄ5 ＝0.1802 ｒ6 ＝2.4229（非球面） ｄ6 ＝0.5160 ｎ3 ＝1.72916 ν3 ＝54.68 ｒ7 ＝-16.6121 ｄ7 ＝0.0164 ｒ8 ＝∞ ｄ8 ＝0.5078 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ9 ＝∞ ｄ9 ＝0.0246 ｒ10＝∞ ｄ10＝0.3276 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ11＝∞ ｄ11＝0.2457 ｒ12＝∞ ｄ12＝0.8190 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ13＝∞ 非球面係数 （第４面）Ｐ＝1.0000，Ｅ＝0.24824 ×10-1 （第６面）Ｐ＝1.0000，Ｅ＝-0.26080 ｜ｆ1/ｆ2 |＝0.74 ，ｄ／ｆ＝0.775 ，｜ｈc/ｈm ｜
＝0.245 ，0.31 実施例１０ ｆ＝1.000 ，Ｆ/2.717，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.3317 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝0.9017 ｄ2 ＝0.7839 ｒ3 ＝2.1170 ｄ3 ＝0.8543 ｎ2 ＝1.92286 ν2 ＝21.29 ｒ4 ＝-3.7880 （非球面）ｄ4 ＝0.0402 ｒ5 ＝∞（絞り） ｄ5 ＝0.4824 ｒ6 ＝3.0647 ｄ6 ＝0.5126 ｎ3 ＝1.81600 ν3 ＝46.62 ｒ7 ＝-4.2574 （非球面）ｄ7 ＝0.0201 ｒ8 ＝∞ ｄ8 ＝0.5226 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ9 ＝∞ ｄ9 ＝0.0201 ｒ10＝∞ ｄ10＝0.3317 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ11＝∞ ｄ11＝0.4322 ｒ12＝∞ ｄ12＝0.8342 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ13＝∞ 非球面係数 （第４面）Ｐ＝1.0000，Ｅ＝-0.39304×10-1 （第７面）Ｐ＝1.0000，Ｅ＝0.11972 ｜ｆ1/ｆ2 |＝0.65 ，ｄ／ｆ＝0.95 ，｜ｈc/ｈm ｜＝
0.05 ，1.14 実施例１１ ｆ＝1.000 ，Ｆ/2.791，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.3876 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.0210 ｄ2 ＝0.7969 ｒ3 ＝2.5204 ｄ3 ＝0.8105 ｎ2 ＝1.92286 ν2 ＝21.29 ｒ4 ＝18.3305 ｄ4 ＝0.0376 ｒ5 ＝∞（絞り） ｄ5 ＝0.4867 ｒ6 ＝2.8587 （非球面）ｄ6 ＝0.5012 ｎ3 ＝1.60300 ν3 ＝65.48 ｒ7 ＝-1.2734 （非球面）ｄ7 ＝0.0159 ｒ8 ＝∞ ｄ8 ＝0.4990 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ9 ＝∞ ｄ9 ＝0.0241 ｒ10＝∞ ｄ10＝0.3219 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ11＝∞ ｄ11＝0.8370 ｒ12＝∞ ｄ12＝0.8048 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ13＝∞ 非球面係数 （第６面）Ｐ＝1.0000，Ｅ＝-0.74331×10-1 （第７面）Ｐ＝1.0000，Ｅ＝0.67664 ×10-1 ｜ｆ1/ｆ2 |＝0.37 ，ｄ／ｆ＝1.228 ，｜ｈc/ｈm ｜
＝0.65 ，0.9 実施例１２ ｆ＝1.000 ，Ｆ/2.881，２ω＝100 ° ｒ1 ＝∞ ｄ1 ＝0.2865 ｎ1 ＝1.88300 ν1 ＝40.78 ｒ2 ＝1.1064 （非球面）ｄ2 ＝0.7092 ｒ3 ＝1.4467 （非球面）ｄ3 ＝0.7163 ｎ2 ＝1.88300 ν2 ＝40.78 ｒ4 ＝-1.9231 ｄ4 ＝0.3582 ｒ5 ＝∞（絞り） ｄ5 ＝0.0215 ｒ6 ＝5.5434 ｄ6 ＝0.4441 ｎ3 ＝1.72916 ν3 ＝54.68 ｒ7 ＝-2.4913 ｄ7 ＝0.0143 ｒ8 ＝∞ ｄ8 ＝0.4441 ｎ4 ＝1.52000 ν4 ＝74.00 ｒ9 ＝∞ ｄ9 ＝0.0215 ｒ10＝∞ ｄ10＝0.2865 ｎ5 ＝1.52287 ν5 ＝59.89 ｒ11＝∞ ｄ11＝0.3510 ｒ12＝∞ ｄ12＝0.7163 ｎ6 ＝1.51633 ν6 ＝64.15 ｒ13＝∞ 非球面係数 （第２面）Ｐ＝1.0000，Ｂ＝-0.59647×10-1，Ｅ＝0.20
602 Ｆ＝0.41050 ，Ｇ＝0.16288 （第３面）Ｐ＝1.0000，Ｂ＝-0.19702，Ｅ＝-0.13203×
10-1 Ｆ＝0.72757 ×10-1，Ｇ＝-0.14645 ｜ｆ1/ｆ2 |＝0.98 ，ｄ／ｆ＝0.71，｜ｈc/ｈm ｜＝
2.9 ，1.2 ただしｒ1 ，ｒ2 ，・・・ は各レンズの屈折率の曲率半
径、ｄ1 ，ｄ2 ，・・・は各レンズの肉厚およびレンズ間
隔、ｎ1 ，ｎ2 ，・・・ は各レンズの屈折率、ν1 ，ν2
，・・・ は各レンズのアッベ数である。EXAMPLES Examples of the endoscope objective lens of the present invention will be described below. Example 1 f = 1.000, F / 4.290, 2ω = 116 ° r1 = ∞ d1 = 0.5500 n1 = 1.88300 ν1 = 40.78 r2 = 0.9454 d2 = 1.2300 r3 = 4.0175 d3 = 0.8600 n2 = 1.88300 ν2 = 40.78 882 = 0.4000 r5 = 33.6773 d5 = 1.0300 n3 = 1.72916 ν3 = 54.68 r6 = -2.3068 d6 = 0.0200 r7 = ∞ (aperture) d7 = 0.5600 n4 = 1.52000 ν4 = 74.00 r8 = ∞ d8 = 600 d9 = 0.0300 1.52287 ν5 = 59.89 r10 = ∞ d10 = 0.8000 r11 = ∞ d11 = 0.9400 n6 = 1.51633 ν6 = 64.15 r12 = ∞ | f1 / f2 | = 0.55, d / f = 1.16 Example 2 f = 0.965, F / 3.993, 2ω = 135 ° r1 = ∞ d1 = 0.3738 n1 = 1.88300 ν1 ＝ 40.78 r2 ＝ 1.0287 d2 ＝ 1.0469 r3 ＝ 4.6383 d3 ＝ 510510 n2 ＝ 1.88300 ν2 ＝ 40.78 r3 ＝ -6.1647 d4 ＝ 33.20.5 r5 ＝ 0.6367 606 r5 ＝ 0.6367 606 r5 = 54.68 r6 = -2.2529 d6 = 0.0184 r7 = ∞ (aperture) d7 = 0.6181 n4 = 1.52000 ν4 = 74.00 r 8 = ∞ d8 = 0.0280 r9 = ∞ d9 = 0.3988 n5 = 1.52287 ν5 = 59.89 r10 = ∞ d10 = 0.7774 r11 = ∞ d11 = 0.9970 n6 = 1.51633 ν6 = 64.15 r12 = ∞ | f1 / f2 | = 0.371, d / f = 1.19 Example 3 f = 1.000, F / 4.300, 2ω = 100 ° r1 = ∞ d1 = 0.3284 n1 = 1.88300 ν1 = 40.78 r2 = 1.0635 d2 = 0.8128 r3 = 1.7391 d3 = 0.8210 n2 = 1.88300-r4 = 40.78 7.8275 d4 = 0.4105 r5 = ∞ (aperture) d5 = 0.0246 r6 = 6.2260 d6 = 0.5114 n3 = 1.72916 ν3 = 54.68 r7 = -1.7509 d7 = 0.0162 r8 = ∞ d8 = 0.5090 n4 = 1.52000 ν4 = 74.00. r10 = ∞ d10 = 0.3284 n5 = 1.52287 ν5 = 59.89 r11 = ∞ d11 = 0.3801 r12 = ∞ d12 = 0.8210 n6 = 1.51633 ν6 = 64.15 r13 = ∞ | f1 / f2 | = 0.717, d / f = 1.04 Example 4f = 1.001, F / 3.833, 2ω = 100 ° r1 = ∞ d1 = 0.4984 n1 = 1.88300 ν1 = 40.78 r2 = 1.2048 d2 = 0.5708 r3 ＝ ∞ d3 ＝ 0.6431 n2 ＝ 1.51633 ν2 ＝ 64.15 r4 ＝ ∞ d4 ＝ 0.0322 r5 ＝ 1.3000 d5 ＝ 0.7464 n3 ＝ 1.51728 ν3 ＝ 69.56 r6 ＝ -3.0866 d6 ＝ 0.2912 r7 ＝ ∞ ＝ 1.94 d7 ④4 69.56 r8 = -1.0736 d8 = 0.5266 r9 = ∞ d9 = 1.6077 n5 = 1.51633 ν5 = 64.15 r10 = ∞ | f1 / f2 | = 0.727, d / f = 1.28 Example 5 f = 1.000, F / 4.243, 2ω = 100 ° r1 = ∞ d1 = 0.3320 n1 = 1.88300 ν1 = 40.78 r2 = 1.0944 d2 = 0.8216 r3 = 1.4850 d3 = 0.8299 n2 = 1.83400 ν2 = 37.16 r4 = -4.8373 d4 = 0.3734 r8 d6 = 6 (6) = 6 (8) d6 = 0.5228 n3 = 1.81600 ν3 = 46.62 r7 = -2.0380 d7 = 0.0166 r8 = ∞ d8 = 0.5145 n4 = 1.52000 ν4 = 74.00 r9 = ∞ d9 = 0.0249 r10 = ∞ d10 = 0.3320 ν11 = 1.5287 = 5287 = 5287 = 5287 = 0.1411 r12 = ∞ d12 = 0.8299 n6 = 1.51633 ν6 = 64.15 r13 = ∞ | f1 / f2 | = 0.855, d /F=1.17 Example 6 f = 1.001, F / 2.796, 2ω = 100 ° r1 = ∞ d1 = 0.5000 n1 = 1.88300 v1 = 40.78 r2 = 0.9742 d2 = 1.1200 r3 = 1.3171 d3 = 0.7000 n2 = 1.840300 v2 = 3.3918 d4 = 0.2400 r5 = 5.4887 (aspherical surface) d5 = 0.4900 n3 = 1.75500 ν3 = 52.33 r6 = -1.7388 d6 = 0.0200 r7 = ∞ (aperture) d7 = 0.5000 n4 = 1.52000 ν4 = 74.00 r8 = 0.08 ＝ ∞ d9 ＝ 0.3300 n5 ＝ 1.52287 ν5 ＝ 59.89 r10 ＝ ∞ d10 ＝ 0.7500 r11 ＝ ∞ d11 ＝ 0.8200 n6 ＝ 1.51633 ν6 ＝ 64.15 r12 ＝ ∞ Aspherical coefficient P = 1.0000, E = -0.22281, F = -0.12062 × 10 -1 , G =
-0.54320 × 10 -1 | f1 / f2 | = 0.52, d / f = 0.036, | hc / hm |
= 0.37 Example 7 f = 1.000, F / 2.536, 2ω = 100 ° r1 = ∞ d1 = 0.3234 n1 = 1.88300 ν1 = 40.78 r2 = 0.9210 d2 = 0.8003 r3 = 1.2745 d3 = 0.8084 n2 = 1.805187.44 = 4. d4 = 0.4042 r5 = ∞ (aperture) d5 = 0.0243 r6 = 1.2714 d6 = 0.5012 n3 = 1.77250 ν3 = 49.66 r7 = 91.2505 (aspherical surface) d7 = 0.1617 r8 = ∞ d8 = 0.5012 n4 = 9.4000 ν ＝ 0.0243 r10 ＝ ∞ d10 ＝ 0.3234 n5 ＝ 1.52287 ν5 ＝ 59.89 r11 ＝ ∞ d11 ＝ 0.2183 r12 ＝ ∞ d12 ＝ 0.8084 n6 ＝ 1.51633 ν6 ＝ 64.15 r13 ＝ ∞ aspheric coefficient P = 1.0000, E = 0.28326 | f1 / f2 | = 0.58, d / f = 1.05, | hc / hm |
= 0.48 Example 8 f = 1.000, F / 2.808, 2ω = 100 ° r1 = ∞ d1 = 0.3167 n1 = 1.88300 ν1 = 40.78 r2 = 0.9520 d2 = 0.7852 r3 = 1.3451 d3 = 0.8320 n2 = 1.88300 ν2 = 40.78 (Aspherical surface) d4 = 0.4819 r5 = ∞ (aperture) d5 = 0.0238 r6 = 1.8507 (aspherical surface) d6 = 0.4933 n3 = 1.72916 ν3 = 54.68 r7 = -3.1601 d7 = 0.0156 r8 = ∞ d8 = 0.4909 n4 = 1.52000 74.00 r9 = ∞ d9 = 0.0238 r10 = ∞ d10 = 0.3167 n5 = 1.52287 ν5 = 59.89 r11 = ∞ d11 = 0.8234 r12 = ∞ d12 = 0.7918 n6 = 1.51633 ν6 = 64.15 r13 = ∞ aspherical coefficient (4th surface) P = 1.0000, E = 0.53786 × 10 -2 (6th surface) P = 1.0000, E = -0.12945 | f1 / f2 | = 0.626, d / f = 1.12, | hc / hm |
= 0.82, 0.04 Example 9 f = 1.000, F / 2.743, 2ω = 100 ° r1 = ∞ d1 = 0.3276 n1 = 1.88300 ν1 = 40.78 r2 = 0.8369 d2 = 0.8190 r3 = 1.1527 d2 = 0.8190 n2 = 1.834100 ν = -6.3773 (aspherical surface) d4 = 0.1556 r5 = ∞ (aperture) d5 = 0.1802 r6 = 2.4229 (aspherical surface) d6 = 0.5160 n3 = 1.72916 ν3 = 54.68 r7 = -16.6121 d7 = 0.0164 r8 = ∞ d8 = 0.5078 1.52000 ν4 = 74.00 r9 = ∞ d9 = 0.0246 r10 = ∞ d10 = 0.3276 n5 = 1.52287 ν5 = 59.89 r11 = ∞ d11 = 0.2457 r12 = ∞ d12 = 0.8190 n6 = 1.51633 ν6 = 64.15 r13 = ∞ aspherical coefficient ) P = 1.0000, E = 0.24824 × 10 -1 (6th surface) P = 1.0000, E = -0.26080 | f1 / f2 | = 0.74, d / f = 0.775, | hc / hm |
= 0.245, 0.31 Example 10 f = 1.000, F / 2.717, 2ω = 100 ° r1 = ∞ d1 = 0.3317 n1 = 1.88300 ν1 = 40.78 r2 = 0.9017 d2 = 0.7839 r3 = 2.1170 d3 = 0.8543 n2 = 1.92286 ν = -3.7880 (aspherical surface) d4 = 0.0402 r5 = ∞ (aperture) d5 = 0.4824 r6 = 3.0647 d6 = 0.5126 n3 = 1.81600 ν3 = 46.62 r7 = -4.2574 (aspherical surface) d7 = 0.0201 r8 = ∞ d8 = 0.5226 n4 1.52000 ν4 = 74.00 r9 = ∞ d9 = 0.0201 r10 = ∞ d10 = 0.3317 n5 = 1.52287 ν5 = 59.89 r11 = ∞ d11 = 0.4322 r12 = ∞ d12 = 0.8342 n6 = 1.51633 ν6 = 64.15 r13 = ∞ aspherical coefficient ) P = 1.0000, E = -0.39304 × 10 -1 (7th surface) P = 1.0000, E = 0.11972 | f1 / f2 | = 0.65, d / f = 0.95, | hc / hm | =
0.05, 1.14 Example 11 f = 1.000, F / 2.791, 2ω = 100 ° r1 = ∞ d1 = 0.3876 n1 = 1.88300 v1 = 40.78 r2 = 1.0210 d2 = 0.7969 r3 = 2.5204 d3 = 0.8105 n2 = 1.92286 r2 = 4. 18.3305 d4 = 0.0376 r5 = ∞ (aperture) d5 = 0.4867 r6 = 2.8587 (aspherical surface) d6 = 0.5012 n3 = 1.60300 ν3 = 65.48 r7 = -1.2734 (aspherical surface) d7 = 0.0159 r8 = ∞ d8 = 0.4990 n4 = 74.00 r9 = ∞ d9 = 0.0241 r10 = ∞ d10 = 0.3219 n5 = 1.52287 ν5 = 59.89 r11 = ∞ d11 = 0.8370 r12 = ∞ d12 = 0.8048 n6 = 1.51633 ν6 = 64.15 r13 = ∞ aspherical surface coefficient (6th surface) = 1.0000, E = -0.74331 × 10 -1 (7th surface) P = 1.0000, E = 0.76664 × 10 -1 | f1 / f2 | = 0.37, d / f = 1.228, | hc / hm |
= 0.65, 0.9 Example 12 f = 1.000, F / 2.881,2ω = 100 ° r1 = ∞ d1 = 0.2865 n1 = 1.88300 ν1 = 40.78 r2 = 1.1064 (aspherical surface) d2 = 0.7092 r3 = 1.4467 (aspherical surface) d3 = 0.7163 n2 = 1.88300 ν2 ＝ 40.78 r4 ＝ -1.9231 d4 ＝ 0.3582 r5 ＝ ∞ (aperture) d5 ＝ 0.0215 r6 ＝ 5.5434 d6 ＝ 0.4441 n3 ＝ 1.72916 ν3 ＝ 54.68 r8 ＝ －2.4913 d7 ＝ 0.0441 r8 ＝ 0.0143 r8 1.52000 ν4 = 74.00 r9 = ∞ d9 = 0.0215 r10 = ∞ d10 = 0.2865 n5 = 1.52287 ν5 = 59.89 r11 = ∞ d11 = 0.3510 r12 = ∞ d12 = 0.7163 n6 = 1.51633 ν6 = 64.15 r13 = ∞ aspherical coefficient ) P = 1.0000, B = -0.59647 × 10 -1 , E = 0.20
602 F = 0.41050, G = 0.16288 (3rd surface) P = 1.0000, B = -0.19702, E = -0.13203 ×
10 -1 F = 0.72757 x 10 -1 , G = -0.14645 | f1 / f2 | = 0.98, d / f = 0.71, | hc / hm | =
2.9, 1.2 where r1, r2, ... are the radii of curvature of the refractive index of each lens, d1, d2, .. are the wall thickness and lens spacing of each lens, and n1, n2 ,. Rate, ν1, ν2
, ... is the Abbe number of each lens.
【００３０】上記実施例中、実施例１〜５は、球面のみ
で構成されたレンズ系であり、又実施例６〜１２は適当
な位置に少なくとも１面の非球面を設け、Ｆナンバーを
小にした比較的明るいレンズ系とした。これら実施例で
用いる非球面の形状は、光軸をｘ軸に取り像の方向を正
とし、面と光軸の交点を原点とし、ｘ軸と直交する方向
をｙ軸とした時、以下の式で表される。 ここで、Ｃは光軸近傍でこの非球面と接する円の曲率半
径の逆数、Ｐは円錐定数、Ｂ，Ｅ，Ｆ，Ｇは夫々２，
４，６，８次の非球面係数である。Of the above examples, Examples 1 to 5 are lens systems composed of only spherical surfaces, and Examples 6 to 12 are those in which at least one aspherical surface is provided at an appropriate position and the F number is small. It is a relatively bright lens system. The shape of the aspherical surface used in these examples is as follows when the optical axis is taken as the x-axis, the direction of the image is positive, the intersection of the surface and the optical axis is the origin, and the direction orthogonal to the x-axis is the y-axis. It is represented by a formula. Here, C is the reciprocal of the radius of curvature of the circle that is in contact with this aspherical surface in the vicinity of the optical axis, P is the conic constant, and B, E, F, and G are 2, respectively.
These are aspherical coefficients of order 4, 6, and 8.
【００３１】実施例１，２は、夫々図１，２に示す構成
で絞りを第３レンズより像側に配置している。In Embodiments 1 and 2, the diaphragms are arranged on the image side of the third lens with the configurations shown in FIGS. 1 and 2, respectively.
【００３２】上記のようなタイプのレンズ系は、第１レ
ンズでの収差の発生方向と第２，第３レンズでの収差の
発生方向とが基本的に異なることにより、広角な視野を
確保しつつ倍率の色収差をはじめその他の諸収差の補正
をなし得たものである。The lens system of the type described above ensures a wide-angle field of view because the aberration generation directions of the first lens and the second and third lenses are basically different. However, it is possible to correct various aberrations such as chromatic aberration of magnification.
【００３３】尚図中Ｆ１は観察上不要な赤外光を吸収す
る赤外カットフィルター、Ｆ２は観察に不要なレーザー
光を遮断するＹＡＧフィルター、Ｆ３は固体撮像素子の
カバーガラスである。In the figure, F1 is an infrared cut filter for absorbing infrared light unnecessary for observation, F2 is a YAG filter for blocking laser light unnecessary for observation, and F3 is a cover glass for the solid-state image pickup device.
【００３４】実施例３，４，５は夫々図３，図４，図５
に示す構成で、絞りを第２レンズの像側の面から第３レ
ンズの物体側の面までの間に配置したレンズタイプであ
る。Embodiments 3, 4 and 5 are shown in FIGS. 3, 4 and 5, respectively.
It is a lens type having a configuration shown in (1), in which a diaphragm is arranged between the image side surface of the second lens and the object side surface of the third lens.
【００３５】このタイプのレンズ系は、実施例１，２に
示すタイプのレンズ系に比べると、絞りの位置が物体側
に近づいている。そのため第１レンズに入射する主光線
の光線高をより低くすることが出来、対物レンズの細径
化には都合のよい構成である。In this type of lens system, the position of the diaphragm is closer to the object side than the lens systems of the types shown in Examples 1 and 2. Therefore, the height of the principal ray incident on the first lens can be made lower, which is a convenient structure for reducing the diameter of the objective lens.
【００３６】実施例６は、図６に示す構成で、絞りを第
３レンズより像側に配置したもので、又第３レンズの物
体側の面を非球面にしたレンズ系である。この非球面の
形状は、光軸から離れるにしたがってその曲率が緩くな
るもので周辺においては凹の作用を有している凸面であ
る。この面は光軸付近では凸の作用を有しているが周辺
部では凹の作用を有している。そのため中間のＮＡをも
った光束に対しては、収差の発生を抑える効果を有して
おり、周辺光束に対しては、凹の作用を有していて収差
の発生方向の符号が逆の収差補正効果を有している。Example 6 is a lens system in which the diaphragm is arranged on the image side of the third lens, and the object side surface of the third lens is an aspherical surface, having the structure shown in FIG. The shape of this aspherical surface is such that its curvature becomes looser as it moves away from the optical axis, and it is a convex surface having a concave action in the periphery. This surface has a convex action in the vicinity of the optical axis, but has a concave action in the peripheral portion. Therefore, it has the effect of suppressing the occurrence of aberrations with respect to a light beam having an intermediate NA, and has the effect of being concave with respect to the peripheral light beams, and the aberration generation direction has the opposite sign. Has a correcting effect.
【００３７】実施例７，８，１２は、夫々図７，図８，
図１２に示す構成で、絞りを第３レンズの物体側の面に
近接させたもので、又いずれも適切な位置に非球面を設
けている。Embodiments 7, 8 and 12 are shown in FIGS.
In the configuration shown in FIG. 12, the diaphragm is arranged close to the object side surface of the third lens, and in each case, an aspherical surface is provided at an appropriate position.
【００３８】実施例７は、第３レンズの像側の面に曲率
が光軸から離れるにしたがって緩くなり周辺においては
凹の作用を有する凸面である非球面を設けた。この面
は、光軸近傍では凸の作用、中間のＮＡでは緩い凸の作
用、周辺では凹の作用を有しており、中間のＮＡをもっ
た光束に対しては、球面収差、コマ収差の発生を抑えて
いる。また第１レンズで発生した収差を第２レンズで補
正し更に残存する収差を第３レンズの上記非球面の周辺
部の凹面で補正している。In the seventh embodiment, an aspherical surface, which is a convex surface having a concave action in the periphery, is provided on the image side surface of the third lens, the curvature of which gradually decreases as the distance from the optical axis increases. This surface has a convex action in the vicinity of the optical axis, a gentle convex action in the intermediate NA, and a concave action in the peripheral portion. For a light beam having an intermediate NA, spherical aberration and coma aberration are caused. The occurrence is suppressed. Further, the aberration generated in the first lens is corrected by the second lens, and the remaining aberration is corrected by the concave surface of the peripheral portion of the aspherical surface of the third lens.
【００３９】実施例８は、第２レンズの像側の面と第３
レンズの物体側の面に夫々非球面を設けている。第２レ
ンズの像側の面の非球面形状は、光軸から離れるにした
がって曲率が強くなる凹面であり、又第３レンズの物体
側の非球面は、光軸から離れるにしたがって曲率が緩く
なる凸面である。In the eighth embodiment, the image-side surface of the second lens and the third surface
An aspherical surface is provided on the object side surface of the lens. The aspherical shape of the image side surface of the second lens is a concave surface whose curvature increases as it moves away from the optical axis, and the object side aspherical surface of the third lens decreases in curvature as it moves away from the optical axis. It is convex.
【００４０】以上のような形状の非球面を二つ設けるこ
とによってこの二つの面に球面収差とコマ収差の補正作
用をうまく分割し、比較的無理のない非球面形状で加工
しやすいレンズで収差を良好に補正し得るようにした。By providing two aspherical surfaces having the above-described shapes, the correction function of spherical aberration and coma aberration is well divided into these two surfaces, so that the lens is relatively reasonably aspherical and easy to process. So that it can be corrected well.
【００４１】実施例９は図９に示す構成で、絞りを第２
レンズと第３レンズのほぼ中間に配置し、第２レンズの
像側の面と第３レンズの物体側の面に夫々非球面を設け
たものである。The ninth embodiment has the configuration shown in FIG.
It is arranged approximately in the middle of the lens and the third lens, and aspherical surfaces are provided on the image side surface of the second lens and the object side surface of the third lens, respectively.
【００４２】第２レンズの像側の面の非球面形状は、光
軸から離れるにしたがって曲率が緩くなる凸面であり、
第３レンズの物体側の面の非球面は、光軸から離れるに
したがって曲率が緩くなる凸面である。The aspherical shape of the image side surface of the second lens is a convex surface whose curvature becomes gentler as it moves away from the optical axis,
The aspherical surface on the object side of the third lens is a convex surface whose curvature becomes gentler as it moves away from the optical axis.
【００４３】実施例１０，１１は夫々図１０、１１に示
す構成で、絞りを第２レンズの像側の面に近接させ配置
したものである。The tenth and eleventh embodiments have the configurations shown in FIGS. 10 and 11, respectively, in which the diaphragm is arranged close to the image side surface of the second lens.
【００４４】実施例１０は、第２レンズの像側の面と第
３レンズの像側の面に夫々非球面を設けられている。そ
のうち第２レンズの像側の面の形状は、光軸から離れる
にしたがって曲率が強くなる凸面であり、又第３レンズ
の像側の面の形状は、光軸から離れるにしたがって曲率
が緩くなって周辺では凹の作用を有する凸面である。In Example 10, aspherical surfaces are provided on the image side surface of the second lens and the image side surface of the third lens, respectively. Of these, the shape of the image side surface of the second lens is a convex surface whose curvature increases as it moves away from the optical axis, and the shape of the image side surface of the third lens decreases in curvature as it moves away from the optical axis. In the periphery, it is a convex surface having a concave action.
【００４５】実施例３〜５のように、細径化しやすい構
成の対物レンズの場合、像面湾曲の補正が他の収差に比
べて不十分である。As in Examples 3 to 5, in the case of an objective lens having a structure in which the diameter can be easily reduced, the correction of the field curvature is insufficient as compared with other aberrations.
【００４６】この実施例１０は、絞り直前の第２レンズ
の像側の面と、絞りから少し離れた第３レンズの像側の
面に非球面を設けて、球面収差、コマ収差の補正に加え
て同時に像面湾曲の補正も行なっている。In the tenth embodiment, an aspherical surface is provided on the image side surface of the second lens immediately before the stop and the image side surface of the third lens slightly away from the stop to correct spherical aberration and coma. In addition, the field curvature is corrected at the same time.
【００４７】上記第３レンズの像側の面では、主光線の
高さが若干高いために、像面湾曲の補正を同時に行なう
ことが出来る。しかし主光線の光線高が像面湾曲を十分
補正出来るほど高くないので、これを補うために、非球
面の形状は、光軸から周辺にかけて凸面から凹面に変化
するような非球面度の高いものになっており、球面収差
とコマ収差は、補正過剰になる。そこで主光線に関係す
る収差には効かない第２レンズの像側の面を球面収差，
コマ収差を発生させる形状の非球面にし、レンズ系全体
の諸収差が良好に補正されるようにした。On the image side surface of the third lens, the height of the chief ray is slightly high, so that the field curvature can be corrected at the same time. However, the ray height of the chief ray is not high enough to correct the field curvature, so to compensate for this, the shape of the aspheric surface has a high degree of asphericity that changes from convex to concave from the optical axis to the periphery. Therefore, spherical aberration and coma are overcorrected. Therefore, the surface on the image side of the second lens, which is not effective for the aberration related to the chief ray, is spherical aberration,
The shape of the aspherical surface is such that coma is generated, and various aberrations of the entire lens system are corrected well.
【００４８】実施例１１は、第３レンズの両面に非球面
を設けた。In Example 11, aspherical surfaces were provided on both surfaces of the third lens.
【００４９】第３レンズの物体側の面の形状は、光軸か
ら離れるにしたがって曲率が緩くなる凸面であり、又像
側の面も同様の形状の非球面である。The shape of the object side surface of the third lens is a convex surface whose curvature becomes gentler as it moves away from the optical axis, and the image side surface is also an aspherical surface of the same shape.
【００５０】この実施例１１は、絞りから少し離れた第
３レンズの物体側および像側の面に非球面を設けて、実
施例１０と同様の効果を持たせるとともに球面収差、コ
マ収差および像面湾曲の補正作用をうまく分割させるこ
とによって非球面度が比較的緩く加工が容易な非球面形
状とすることが出来る。In the eleventh embodiment, an aspherical surface is provided on the object-side surface and the image-side surface of the third lens, which is slightly away from the stop, to obtain the same effect as that of the tenth embodiment, and spherical aberration, coma and image. By properly dividing the correction effect of the surface curvature, an aspherical surface having a relatively low asphericity and easy to process can be formed.
【００５１】実施例１２は、実施例３のレンズ系を大口
径化したもので、第１レンズの像側の面と第２レンズの
物体側の面を夫々非球面にした。In Example 12, the lens system of Example 3 was enlarged, and the image-side surface of the first lens and the object-side surface of the second lens were made aspheric.
【００５２】第１レンズの像側の面を、光軸から離れる
にしたがって曲率が強くなる凹面の非球面とし又第２レ
ンズの物体側の面を光軸から離れるにしたがって曲率が
緩くなる凸面の非球面にした。The image-side surface of the first lens is a concave aspherical surface whose curvature increases as it moves away from the optical axis, and the object-side surface of the second lens has a convex surface whose curvature decreases as it moves away from the optical axis. I made it aspheric.
【００５３】ここで第１レンズの像側の面は、主光線の
光線高とマージナル光線の光線高との比が２．９：１で
あり、非球面の設置範囲を規定した条件（３）を満足し
ない。しかし、この比率が示すように、第１レンズの像
側の面では、主光線の光線高が高いので上記のような非
球面形状をもたせ、光軸から離れるほど主光線を屈曲さ
せるようにして、実施例３では補正しきれなかった像面
湾曲も良好に補正している。また条件（３）を満足する
非球面をもう１面設けて球面収差、コマ収差の補正も行
なっている。Here, on the image side surface of the first lens, the ratio of the ray height of the principal ray to the ray height of the marginal ray is 2.9: 1, and the condition (3) which defines the installation range of the aspherical surface. Not satisfied. However, as shown by this ratio, since the ray height of the chief ray is high on the image-side surface of the first lens, the chief ray should be bent as it moves away from the optical axis because the ray height of the chief ray is high. The field curvature, which cannot be completely corrected in the third embodiment, is also corrected well. Further, another aspherical surface satisfying the condition (3) is provided to correct spherical aberration and coma.
【００５４】[0054]
【発明の効果】本発明は、負のパワーの第１レンズと正
のパワーの第２、第３レンズの単レンズ３枚で、絞りを
第２レンズから像面までの間に配置することにより絞り
の前に少なくとも１枚正のパワーのレンズが来るように
して、第１レンズで発生する倍率の色収差をはじめとす
る諸収差を良好に補正されしかもコンパクトな内視鏡対
物レンズを実現したものである。更に上記レンズ系で、
適宜位置に非球面を１面以上設ければ明るい大口径の対
物レンズになし得る。According to the present invention, the first lens having negative power and the second and third lenses having positive power have three single lenses, and the diaphragm is arranged between the second lens and the image plane. At least one positive power lens comes in front of the diaphragm, and various aberrations such as chromatic aberration of magnification generated by the first lens are well corrected, and a compact endoscope objective lens is realized. Is. Furthermore, with the above lens system,
If one or more aspherical surfaces are provided at appropriate positions, a bright large-diameter objective lens can be obtained.
【図１】本発明の実施例１の断面図FIG. 1 is a sectional view of a first embodiment of the present invention.
【図２】本発明の実施例２の断面図FIG. 2 is a sectional view of a second embodiment of the present invention.
【図３】本発明の実施例３の断面図FIG. 3 is a sectional view of a third embodiment of the present invention.
【図４】本発明の実施例４の断面図FIG. 4 is a sectional view of a fourth embodiment of the present invention.
【図５】本発明の実施例５の断面図FIG. 5 is a sectional view of a fifth embodiment of the present invention.
【図６】本発明の実施例６の断面図FIG. 6 is a sectional view of a sixth embodiment of the present invention.
【図７】本発明の実施例７の断面図FIG. 7 is a sectional view of a seventh embodiment of the present invention.
【図８】本発明の実施例８の断面図FIG. 8 is a sectional view of an eighth embodiment of the present invention.
【図９】本発明の実施例９の断面図FIG. 9 is a sectional view of a ninth embodiment of the present invention.
【図１０】本発明の実施例１０の断面図FIG. 10 is a sectional view of Example 10 of the present invention.
【図１１】本発明の実施例１１の断面図FIG. 11 is a sectional view of Embodiment 11 of the present invention.
【図１２】本発明の実施例１２の断面図FIG. 12 is a sectional view of embodiment 12 of the present invention.
【図１３】本発明の実施例１の収差曲線図FIG. 13 is an aberration curve diagram of Example 1 of the present invention.
【図１４】本発明の実施例２の収差曲線図FIG. 14 is an aberration curve diagram of Example 2 of the present invention.
【図１５】本発明の実施例３の収差曲線図FIG. 15 is an aberration curve diagram of Example 3 of the present invention.
【図１６】本発明の実施例４の収差曲線図FIG. 16 is an aberration curve diagram for Example 4 of the present invention.
【図１７】本発明の実施例５の収差曲線図FIG. 17 is an aberration curve diagram of Example 5 of the present invention.
【図１８】本発明の実施例６の収差曲線図FIG. 18 is an aberration curve diagram for Example 6 of the present invention.
【図１９】本発明の実施例７の収差曲線図FIG. 19 is an aberration curve diagram of Example 7 of the present invention.
【図２０】本発明の実施例８の収差曲線図FIG. 20 is an aberration curve diagram of Example 8 of the present invention.
【図２１】本発明の実施例９の収差曲線図FIG. 21 is an aberration curve diagram of Example 9 of the present invention.
【図２２】本発明の実施例１０の収差曲線図FIG. 22 is an aberration curve diagram of Example 10 of the present invention.
【図２３】本発明の実施例１１の収差曲線図FIG. 23 is an aberration curve diagram of Example 11 of the present invention.
【図２４】本発明の実施例１２の収差曲線図FIG. 24 is an aberration curve diagram for Example 12 of the present invention.
Claims (1)
レンズと、正の屈折力を有する第２レンズと、正の屈折
力を有する第３レンズとよりなる３枚構成の対物レンズ
で、絞りが上記第２レンズから像面までの間に配置され
ることを特徴とする内視鏡対物レンズ。1. A first lens element having a negative refractive power in order from the object side.
A three-lens objective lens including a lens, a second lens having a positive refracting power, and a third lens having a positive refracting power, and a diaphragm disposed between the second lens and the image plane. An endoscope objective lens characterized in that
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13530491A JP3206930B2 (en) | 1991-05-13 | 1991-05-13 | Endoscope objective lens |
| US07/845,944 US5223982A (en) | 1991-03-05 | 1992-03-04 | Objective lens system for endoscopes |
| US08/236,680 US5436767A (en) | 1991-03-05 | 1994-05-02 | Objective lens system for endoscopes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13530491A JP3206930B2 (en) | 1991-05-13 | 1991-05-13 | Endoscope objective lens |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05107470A true JPH05107470A (en) | 1993-04-30 |
| JP3206930B2 JP3206930B2 (en) | 2001-09-10 |
Family
ID=15148586
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13530491A Expired - Lifetime JP3206930B2 (en) | 1991-03-05 | 1991-05-13 | Endoscope objective lens |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3206930B2 (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09269450A (en) * | 1996-03-29 | 1997-10-14 | Olympus Optical Co Ltd | Objective lens for endoscope |
| JPH1020188A (en) * | 1996-07-03 | 1998-01-23 | Asahi Optical Co Ltd | Photographing lens |
| JPH10170821A (en) * | 1996-12-16 | 1998-06-26 | Olympus Optical Co Ltd | Objective lens for endoscope |
| JP2001159732A (en) * | 1999-12-02 | 2001-06-12 | Nikon Corp | Super wide angle lens and photographic device having the lens |
| WO2004102247A1 (en) * | 2003-05-15 | 2004-11-25 | Olympus Corporation | Object lens and endoscope using it |
| US7379252B2 (en) | 2005-03-30 | 2008-05-27 | Pentax Corporation | Endoscope objective lens system |
| WO2011027622A1 (en) * | 2009-09-01 | 2011-03-10 | オリンパスメディカルシステムズ株式会社 | Objective optical system |
| KR101429899B1 (en) * | 2013-04-10 | 2014-08-13 | 주식회사 세코닉스 | Compact type wide angle lens system |
| JP2014160104A (en) * | 2013-02-19 | 2014-09-04 | Nikon Corp | Optical system, optical device, and method for manufacturing optical system |
| JP2015132759A (en) * | 2014-01-15 | 2015-07-23 | パナソニックＩｐマネジメント株式会社 | Wide-angle lens system, camera |
| WO2017068726A1 (en) * | 2015-10-23 | 2017-04-27 | オリンパス株式会社 | Imaging device and optical device provided with same |
| US9915803B2 (en) | 2013-02-19 | 2018-03-13 | Nikon Corporation | Optical system, optical apparatus, and method for manufacturing the optical system |
| WO2021166027A1 (en) * | 2020-02-17 | 2021-08-26 | オリンパス株式会社 | Objective optical system, imaging device, and endoscope |
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| JP2008102500A (en) | 2006-09-19 | 2008-05-01 | Fujinon Corp | Imaging lens and camera system including the same lens |
| JP4815319B2 (en) | 2006-09-29 | 2011-11-16 | 富士フイルム株式会社 | Imaging lens and camera device provided with the same |
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Cited By (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09269450A (en) * | 1996-03-29 | 1997-10-14 | Olympus Optical Co Ltd | Objective lens for endoscope |
| JPH1020188A (en) * | 1996-07-03 | 1998-01-23 | Asahi Optical Co Ltd | Photographing lens |
| JPH10170821A (en) * | 1996-12-16 | 1998-06-26 | Olympus Optical Co Ltd | Objective lens for endoscope |
| JP2001159732A (en) * | 1999-12-02 | 2001-06-12 | Nikon Corp | Super wide angle lens and photographic device having the lens |
| WO2004102247A1 (en) * | 2003-05-15 | 2004-11-25 | Olympus Corporation | Object lens and endoscope using it |
| US7379252B2 (en) | 2005-03-30 | 2008-05-27 | Pentax Corporation | Endoscope objective lens system |
| DE102006014887B4 (en) * | 2005-03-30 | 2010-04-22 | Hoya Corp. | Endoscope objective lens system |
| US8531781B2 (en) | 2009-09-01 | 2013-09-10 | Olympus Medical Systems Corp. | Objective optical system |
| WO2011027622A1 (en) * | 2009-09-01 | 2011-03-10 | オリンパスメディカルシステムズ株式会社 | Objective optical system |
| JP2014160104A (en) * | 2013-02-19 | 2014-09-04 | Nikon Corp | Optical system, optical device, and method for manufacturing optical system |
| US9915803B2 (en) | 2013-02-19 | 2018-03-13 | Nikon Corporation | Optical system, optical apparatus, and method for manufacturing the optical system |
| KR101429899B1 (en) * | 2013-04-10 | 2014-08-13 | 주식회사 세코닉스 | Compact type wide angle lens system |
| JP2015132759A (en) * | 2014-01-15 | 2015-07-23 | パナソニックＩｐマネジメント株式会社 | Wide-angle lens system, camera |
| WO2017068726A1 (en) * | 2015-10-23 | 2017-04-27 | オリンパス株式会社 | Imaging device and optical device provided with same |
| JPWO2017068726A1 (en) * | 2015-10-23 | 2018-08-09 | オリンパス株式会社 | Imaging apparatus and optical apparatus including the same |
| US10634884B2 (en) | 2015-10-23 | 2020-04-28 | Olympus Corporation | Image pickup apparatus and optical apparatus using the same |
| WO2021166027A1 (en) * | 2020-02-17 | 2021-08-26 | オリンパス株式会社 | Objective optical system, imaging device, and endoscope |
| EP4152071A1 (en) * | 2021-09-17 | 2023-03-22 | Altek Biotechnology Corporation | Optical imaging lens assembly and endoscopic optical device |
| US11832791B2 (en) | 2021-09-17 | 2023-12-05 | Altek Biotechnology Corporation | Optical imaging lens assembly and endoscopic optical device |
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| JP3206930B2 (en) | 2001-09-10 |
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