WO2019207699A1 - Objective optical system and imaging device using same - Google Patents

Objective optical system and imaging device using same Download PDF

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Publication number
WO2019207699A1
WO2019207699A1 PCT/JP2018/016935 JP2018016935W WO2019207699A1 WO 2019207699 A1 WO2019207699 A1 WO 2019207699A1 JP 2018016935 W JP2018016935 W JP 2018016935W WO 2019207699 A1 WO2019207699 A1 WO 2019207699A1
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lens
lens group
optical system
objective optical
refractive power
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PCT/JP2018/016935
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French (fr)
Japanese (ja)
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水澤聖幸
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オリンパス株式会社
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Priority to PCT/JP2018/016935 priority Critical patent/WO2019207699A1/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/04—Reversed telephoto objectives

Definitions

  • the present invention relates to an objective optical system and an imaging apparatus using the objective optical system.
  • Patent Document 1 A small imaging optical system having an inner focus function is disclosed in Patent Document 1 and Patent Document 2.
  • the angle of view variation during focusing is slightly large.
  • the F number is slightly large and the focusing range is narrow.
  • the present invention has been made in view of such problems, and uses an objective optical system that has a wide angle, has a small angle of view variation at the time of focusing, and has various aberrations corrected satisfactorily.
  • An object is to provide an imaging device.
  • an objective optical system includes: From the object side, A first lens group having negative refractive power; A second lens group; The aperture stop, A third lens group having a positive refractive power, During focusing, the second lens group moves along the optical axis, The second lens group includes a positive lens and a negative lens.
  • An imaging apparatus includes: The above-described objective optical system, an image sensor, a control unit, and a calculation unit,
  • the image sensor receives an optical image generated by the objective optical system
  • the control unit moves the second lens group to the near point photographing position and the far point photographing position
  • the near-point image at the near-point shooting position and the far-point image at the far-point shooting position are acquired by the image sensor
  • the computing unit synthesizes the near point image and the far point image.
  • an objective optical system that has a wide angle, has a small angle of view variation during focusing, and has various aberrations corrected well, and an imaging apparatus using the objective optical system.
  • FIG. 1 is a cross-sectional view of an objective optical system according to Example 1.
  • FIG. 6 is a cross-sectional view of an objective optical system according to Example 2.
  • FIG. 6 is a sectional view of an objective optical system according to Example 3.
  • FIG. 6 is a cross-sectional view of an objective optical system according to Example 4.
  • FIG. 4 is an aberration diagram of the objective optical system according to Example 1.
  • FIG. 6 is an aberration diagram of the objective optical system according to Example 2.
  • FIG. 6 is an aberration diagram of an objective optical system according to Example 3.
  • FIG. 10 is an aberration diagram of the objective optical system according to Example 4.
  • the objective optical system according to the present embodiment can observe an object located at a long distance and an object located at a short distance with a single optical system. Therefore, in the objective optical system according to the present embodiment, the optical system is configured by a plurality of lens groups, and one lens group moves on the optical axis. Thereby, an optical image when focusing on a long-distance object and an optical image when focusing on a short-distance object are formed.
  • the objective optical system includes, in order from the object side, a first lens group having negative refractive power, a second lens group, an aperture stop, and a third lens group having positive refractive power,
  • the second lens group moves along the optical axis during focusing, and the second lens group includes a positive lens and a negative lens.
  • the objective optical system according to the present embodiment includes, in order from the object side, a first lens group having a negative refractive power, a second lens group, and a third lens group having a positive refractive power. By doing so, it is possible to secure a wide angle of view and shorten the overall length of the optical system.
  • a lens group having negative refractive power is positioned on the object side, and a lens group having positive refractive power is positioned on the image side.
  • the first lens group having a negative refractive power is located on the object side, and the third lens group having a positive refractive power is located on the image side. Therefore, the objective optical system of the present embodiment employs a retrofocus type optical system. Therefore, a long back focus can be secured.
  • Object distance differs between long-distance objects and short-distance objects. In observing an object, it is preferable that a clear image is formed even if the object distance changes. For this purpose, it is necessary to move at least one lens group.
  • the number of lens groups to be moved is small. If the number of lens groups to be moved is one, the driving mechanism can be simplified. In the objective optical system of the present embodiment, the second lens group moves during focusing. Since the number of moving lens groups is one, the focusing mechanism can be simplified.
  • the second lens group includes a positive lens and a negative lens. Therefore, the refractive power of the second lens group is small. As a result, it is possible to reduce the angle of view variation during focusing.
  • the objective optical system according to the present embodiment preferably satisfies the following conditional expression (1). -3.5 ⁇ f2n / f2p ⁇ -1.5 (1) here, f2p is the focal length of the positive lens in the second lens group, f2n is the focal length of the negative lens of the second lens group, It is.
  • the refractive power of the positive lens is relatively larger than the refractive power of the negative lens.
  • an aberration affected by the positive lens for example, a negative spherical aberration occurs.
  • the imaging performance deteriorates.
  • the refractive power of the negative lens is relatively larger than the refractive power of the positive lens.
  • an aberration affected by the negative lens for example, a positive spherical aberration occurs.
  • the imaging performance deteriorates.
  • the objective optical system according to the present embodiment preferably satisfies the following conditional expression (2). 5 ⁇ f2 / ffar ⁇ 8 (2) here, f2 is the focal length of the second lens group, ffar is the focal length of the entire objective optical system when focusing on the farthest object, It is.
  • the focal length of the second lens group becomes too long. Therefore, the focusing range is narrowed.
  • the focusing range can be expanded by increasing the amount of movement of the second lens group. However, if the amount of movement of the second lens group is increased, the overall length of the optical system becomes longer.
  • the third lens group includes, in order from the object side, an aperture stop, a first lens component, a second lens component, and a third lens component.
  • the first lens component is a single lens having a positive refractive power or a cemented lens having a positive refractive power
  • the second lens component is a single lens having a negative refractive power or a negative refractive power.
  • the third lens component is a single lens having a positive refractive power or a cemented lens having a positive refractive power.
  • the first lens component has a positive refractive power
  • the second lens component has a negative refractive power
  • the third lens component has a positive refractive power. Therefore, in the objective optical system according to the present embodiment, a portion in which the refractive power is arranged to have a positive refractive power, a negative refractive power, and a positive refractive power is formed in the third lens group.
  • Such an arrangement of refractive power is the same as the arrangement of refractive power in a triplet lens. Therefore, in the objective optical system according to the present embodiment, it can be considered that a triplet lens is arranged in the third lens group.
  • the triplet lens can achieve both a small F-number and a wide angle of view. Therefore, the objective optical system according to the present embodiment can achieve both a small F number and a wide angle of view.
  • the first lens group includes an object-side lens and an image-side lens
  • the object-side lens is a surface whose image side surface is concave on the image side. Is an object side concave surface on the object side, the image side lens is arranged next to the object side lens, It is preferable that the image side surface of the object side lens and the object side surface of the image side lens face each other.
  • the image side surface of the object side lens has negative refractive power.
  • the object side surface of the image side lens has negative refractive power. Therefore, in the objective optical system according to the present embodiment, the negative refractive power of the first lens group can be shared by the two lens surfaces. Therefore, a wide angle of view can be secured while suppressing the occurrence of various aberrations.
  • the image side surface of the object side lens faces the object side surface of the image side lens. Therefore, the angle of view can be widened while reducing curvature of field and astigmatism.
  • both the positive lens and the negative lens of the second lens group are meniscus lenses having a convex surface facing the object side.
  • the positive lens of the second lens group is located closer to the object side than the negative lens of the second lens group.
  • the third lens group includes a fourth lens component and a fifth lens component
  • the fourth lens component includes a single lens or a cemented lens.
  • the lens component 5 is preferably a cemented lens.
  • the fourth lens component and the fifth lens component of the third lens group are disposed near the image plane. At this position, the on-axis light beam and the off-axis light beam are separated. Therefore, the off-axis aberration can be favorably corrected with the fourth lens component and the fifth lens component. Since the fifth lens component is composed of a cemented lens, the lateral chromatic aberration can be particularly favorably corrected.
  • An imaging apparatus includes the above-described objective optical system, an imaging element, a control unit, and a calculation unit.
  • the imaging element receives an optical image generated by the objective optical system, and receives a control unit.
  • the second lens group is moved to the near point photographing position and the far point photographing position, the near point image at the near point photographing position and the far point image at the far point photographing position are acquired by the imaging device, , The near point image and the far point image are synthesized.
  • (A) is a lens cross-sectional view when focusing on a long-distance object
  • (b) is a lens cross-sectional view when focusing on a short-distance object.
  • SA spherical aberration
  • AS astigmatism
  • DT distortion aberration
  • SA Spherical aberration
  • AS Astigmatism
  • DT Distortion aberration
  • the first lens group is indicated by G1
  • the second lens group is indicated by G2
  • the third lens group is indicated by G3
  • the aperture stop is indicated by S
  • the image surface is indicated by I.
  • a parallel plate CG1 and a parallel plate CG2 are disposed between the third lens group G3 and the image plane I.
  • the parallel plate CG1 is a cover glass of the image sensor, and the parallel plate CG2 is a sealing glass.
  • a gap is formed between the parallel plate CG2 and the image plane I.
  • the image plane I may be located on the image side surface of the parallel plate CG2.
  • the objective optical system of Example 1 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3.
  • the first lens group G1 includes a plano-concave negative lens L1 having a plane on the object side, a biconcave negative lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.
  • the second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
  • the third lens group G3 includes a biconvex positive lens L6, a biconcave negative lens L7, a positive meniscus lens L8 having a convex surface facing the image side, a biconvex positive lens L9, and a negative meniscus having a convex surface facing the image side. It has a lens L10, a biconvex positive lens L11, and a negative meniscus lens L12 having a convex surface facing the image side.
  • the biconvex positive lens L9 and the negative meniscus lens L10 are cemented.
  • the biconvex positive lens L11 and the negative meniscus lens L12 are cemented.
  • the aperture stop S is disposed between the second lens group G2 and the third lens group G3. More specifically, the aperture stop S is disposed in the vicinity of the surface closest to the object side of the third lens group G3.
  • the second lens group G2 moves.
  • the second lens group G2 moves to the image side.
  • the aperture stop S is fixed together with the third lens group G3.
  • a parallel plate CG1 and a parallel plate CG2 are arranged on the image side of the third lens group G3.
  • the objective optical system of Example 2 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3.
  • the first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the image side, and a negative meniscus lens L3 having a convex surface facing the image side.
  • the second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
  • the third lens group G3 includes a biconvex positive lens L6, a negative meniscus lens L7 having a convex surface on the image side, a positive meniscus lens L8 having a convex surface on the image side, a biconvex positive lens L9, and an image side. It has a negative meniscus lens L10 having a convex surface, a biconvex positive lens L11, and a negative meniscus lens L12 having a convex surface facing the image side.
  • the biconvex positive lens L9 and the negative meniscus lens L10 are cemented.
  • the biconvex positive lens L11 and the negative meniscus lens L12 are cemented.
  • the aperture stop S is disposed between the second lens group G2 and the third lens group G3. More specifically, the aperture stop S is disposed in the vicinity of the surface closest to the object side of the third lens group G3.
  • the second lens group G2 moves.
  • the second lens group G2 moves to the image side.
  • the aperture stop S is fixed together with the third lens group G3.
  • a parallel plate CG1 and a parallel plate CG2 are arranged on the image side of the third lens group G3.
  • the objective optical system of Example 3 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3.
  • the first lens group G1 includes a planoconcave negative lens L1, a biconcave negative lens L2, and a biconvex positive lens L3.
  • the biconcave negative lens L2 and the biconvex positive lens L3 are cemented.
  • the second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
  • the third lens group G3 includes a biconvex positive lens L6, a biconcave negative lens L7, a biconvex positive lens L8, a biconvex positive lens L9, a negative meniscus lens L10 having a convex surface facing the object side, and a biconvex lens.
  • a positive lens L11 and a negative meniscus lens L12 having a convex surface facing the image side.
  • the concave negative lens L7 and the biconvex positive lens L8 are cemented.
  • the biconvex positive lens L11 and the negative meniscus lens L12 are cemented.
  • the aperture stop S is disposed between the second lens group G2 and the third lens group G3. More specifically, the aperture stop S is disposed in the vicinity of the surface closest to the object side of the third lens group G3.
  • the second lens group G2 moves.
  • the second lens group G2 moves to the image side.
  • the aperture stop S is fixed together with the third lens group G3.
  • a parallel plate CG1 and a parallel plate CG2 are arranged on the image side of the third lens group G3.
  • the objective optical system of Example 4 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3.
  • the first lens group G1 includes a plano-concave negative lens L1 having a flat surface on the object side, a negative meniscus lens L2 having a convex surface facing the image side, and a positive meniscus lens L3 having a convex surface facing the object side.
  • the second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
  • the third lens group G3 includes a biconvex positive lens L6, a biconcave negative lens L7, a biconvex positive lens L8, a biconvex positive lens L9, a biconvex positive lens L10, and a negative with a convex surface facing the image side. Meniscus lens L11.
  • the biconvex positive lens L10 and the negative meniscus lens L11 are cemented.
  • the aperture stop S is disposed between the second lens group G2 and the third lens group G3. More specifically, the aperture stop S is disposed in the vicinity of the surface closest to the object side of the third lens group G3.
  • the second lens group G2 moves.
  • the second lens group G2 moves to the image side.
  • the aperture stop S is fixed together with the third lens group G3.
  • a parallel plate CG1 and a parallel plate CG2 are arranged on the image side of the third lens group G3.
  • r is the radius of curvature of each lens surface
  • d is the distance between the lens surfaces
  • ne is the refractive index of the e-line of each lens
  • ⁇ d is the Abbe number of each lens.
  • the long distance is when the long distance object is focused
  • the short distance is when the short distance object is focused
  • OB is the object distance
  • f is the focal length of the entire system
  • FNO is the F number
  • ⁇ is the half field angle
  • IH is the image height.
  • f1, f2,... are focal lengths of the lens groups.
  • Example 1 Example 2
  • Example 3 Example 4 f2n / f2p -1.914 -1.466 -3.553 -2.484 f2 / ffar 7.76 7.46 5.22 5.85
  • the present invention is suitable for an objective optical system in which fluctuations in the angle of view at the time of focusing are small and various aberrations are well corrected, and an imaging apparatus using the objective optical system.

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Abstract

The present invention provides an objective optical system having small angle of view variation during focusing and for which various aberrations are satisfactorily corrected, and an imaging device using the objective optical system. The objective optical system comprises, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2, an aperture stop S, and a third lens group G3 having positive refractive power. During focusing, the second lens group G2 moves along the optical axis. The second lens group G2 comprises a positive lens and a negative lens.

Description

対物光学系及びそれを用いた撮像装置Objective optical system and imaging apparatus using the same
　本発明は、対物光学系及びそれを用いた撮像装置に関する。 The present invention relates to an objective optical system and an imaging apparatus using the objective optical system.
　インナーフォーカス機能を備えた小型の撮像光学系が、特許文献１や特許文献２に開示されている。 A small imaging optical system having an inner focus function is disclosed in Patent Document 1 and Patent Document 2.
国際公開第２０１６／０６７８３号International Publication No. 2016/066783 特許第５９４８５３０号公報Japanese Patent No. 5948530
　特許文献１に開示された撮像光学系では、合焦の際の画角変動がやや大きい。特許文献２に開示された撮像光学系では、Ｆナンバーがやや大きく、合焦範囲が狭い。 In the imaging optical system disclosed in Patent Document 1, the angle of view variation during focusing is slightly large. In the imaging optical system disclosed in Patent Document 2, the F number is slightly large and the focusing range is narrow.
　本発明は、このような課題に鑑みてなされたものであって、広角でありながら、合焦の際の画角変動が小さく、諸収差が良好に補正された対物光学系及びそれを用いた撮像装置を提供することを目的とする。 The present invention has been made in view of such problems, and uses an objective optical system that has a wide angle, has a small angle of view variation at the time of focusing, and has various aberrations corrected satisfactorily. An object is to provide an imaging device.
　上述した課題を解決し、目的を達成するために、本発明の少なくとも幾つかの実施形態に係る対物光学系は、
　物体側から順に、
　負の屈折力を有する第１レンズ群と、
　第２レンズ群と、
　明るさ絞りと、
　正の屈折力を有する第３レンズ群と、からなり、
　合焦時、第２レンズ群は光軸に沿って移動し、
　第２レンズ群は、正レンズと、負レンズと、からなることを特徴とする。 In order to solve the above-described problems and achieve the object, an objective optical system according to at least some embodiments of the present invention includes:
From the object side,
A first lens group having negative refractive power;
A second lens group;
The aperture stop,
A third lens group having a positive refractive power,
During focusing, the second lens group moves along the optical axis,
The second lens group includes a positive lens and a negative lens.
　本発明の少なくとも幾つかの実施形態に係る撮像装置は、
　上述の対物光学系と、撮像素子と、制御部と、演算部と、を備え、
　撮像素子は、対物光学系で生成された光学像を受光し、
　制御部は、第２レンズ群を、近点撮影位置と遠点撮影位置に移動させ、
　近点撮影位置における近点画像と遠点撮影位置における遠点画像とを、撮像素子で取得し、
　演算部は、近点画像と遠点画像とを合成することを特徴とする。 An imaging apparatus according to at least some embodiments of the present invention includes:
The above-described objective optical system, an image sensor, a control unit, and a calculation unit,
The image sensor receives an optical image generated by the objective optical system,
The control unit moves the second lens group to the near point photographing position and the far point photographing position,
The near-point image at the near-point shooting position and the far-point image at the far-point shooting position are acquired by the image sensor,
The computing unit synthesizes the near point image and the far point image.
　本発明によれば、広角でありながら、合焦の際の画角変動が小さく、諸収差が良好に補正された対物光学系及びそれを用いた撮像装置を提供することができる。 According to the present invention, it is possible to provide an objective optical system that has a wide angle, has a small angle of view variation during focusing, and has various aberrations corrected well, and an imaging apparatus using the objective optical system.
実施例１に係る対物光学系の断面図である。1 is a cross-sectional view of an objective optical system according to Example 1. FIG. 実施例２に係る対物光学系の断面図である。6 is a cross-sectional view of an objective optical system according to Example 2. FIG. 実施例３に係る対物光学系の断面図である。FIG. 6 is a sectional view of an objective optical system according to Example 3. 実施例４に係る対物光学系の断面図である。FIG. 6 is a cross-sectional view of an objective optical system according to Example 4. 実施例１に係る対物光学系の収差図である。FIG. 4 is an aberration diagram of the objective optical system according to Example 1. 実施例２に係る対物光学系の収差図である。FIG. 6 is an aberration diagram of the objective optical system according to Example 2. 実施例３に係る対物光学系の収差図である。FIG. 6 is an aberration diagram of an objective optical system according to Example 3. 実施例４に係る対物光学系の収差図である。FIG. 10 is an aberration diagram of the objective optical system according to Example 4.
　実施例の説明に先立ち、本発明のある態様にかかる実施形態の作用効果を説明する。なお、本実施形態の作用効果を具体的に説明するに際しては、具体的な例を示して説明することになる。しかし、後述する実施例の場合と同様に、それらの例示される態様はあくまでも本発明に含まれる態様のうちの一部に過ぎず、その態様には数多くのバリエーションが存在する。したがって、本発明は例示される態様に限定されるものではない。 Prior to the description of the examples, the operational effects of the embodiment according to an aspect of the present invention will be described. It should be noted that, when the operational effects of the present embodiment are specifically described, a specific example will be shown and described. However, as in the case of the embodiments to be described later, those exemplified aspects are only a part of the aspects included in the present invention, and there are many variations in the aspects. Therefore, the present invention is not limited to the illustrated embodiment.
　本実施形態に係る対物光学系は、一つの光学系で、遠距離に位置する物体と近距離に位置する物体とを観察できる。そのために、本実施形態に係る対物光学系では、光学系を複数のレンズ群で構成すると共に、１つのレンズ群が光軸上を移動する。これにより、遠距離物体に合焦したときの光学像と、近距離物体に合焦したときの光学像が形成される。 The objective optical system according to the present embodiment can observe an object located at a long distance and an object located at a short distance with a single optical system. Therefore, in the objective optical system according to the present embodiment, the optical system is configured by a plurality of lens groups, and one lens group moves on the optical axis. Thereby, an optical image when focusing on a long-distance object and an optical image when focusing on a short-distance object are formed.
　本実施形態に係る対物光学系は、物体側から順に、負の屈折力を有する第１レンズ群と、第２レンズ群と、明るさ絞りと、正の屈折力を有する第３レンズ群と、からなり、合焦時、第２レンズ群は光軸に沿って移動し、第２レンズ群は、正レンズと、負レンズと、からなることを特徴とする。 The objective optical system according to this embodiment includes, in order from the object side, a first lens group having negative refractive power, a second lens group, an aperture stop, and a third lens group having positive refractive power, The second lens group moves along the optical axis during focusing, and the second lens group includes a positive lens and a negative lens.
　本実施形態の対物光学系は、物体側から順に、負の屈折力を有する第１レンズ群と、第２レンズ群と、正の屈折力を有する第３レンズ群と、で構成されている。このようにすることで、広い画角の確保と、光学系の全長の短縮ができる。 The objective optical system according to the present embodiment includes, in order from the object side, a first lens group having a negative refractive power, a second lens group, and a third lens group having a positive refractive power. By doing so, it is possible to secure a wide angle of view and shorten the overall length of the optical system.
　レトロフォーカスタイプの光学系では、物体側に負の屈折力を有するレンズ群が位置し、像側に正の屈折力を有するレンズ群が位置している。本実施形態の対物光学系では、負の屈折力を有する第１レンズ群が物体側に位置し、正の屈折力を有する第３レンズ群が像側に位置している。よって、本実施形態の対物光学系では、レトロフォーカスタイプの光学系が採用されている。そのため、長いバックフォーカスを確保できる。 In a retrofocus type optical system, a lens group having negative refractive power is positioned on the object side, and a lens group having positive refractive power is positioned on the image side. In the objective optical system of the present embodiment, the first lens group having a negative refractive power is located on the object side, and the third lens group having a positive refractive power is located on the image side. Therefore, the objective optical system of the present embodiment employs a retrofocus type optical system. Therefore, a long back focus can be secured.
　遠距離物体と近距離物体とでは、物体距離が異なる。物体の観察では、物体距離が変化しても、鮮明な像が形成されることが好ましい。そのためには、レンズ群を少なくとも１つ動かす必要がある。 ∙ Object distance differs between long-distance objects and short-distance objects. In observing an object, it is preferable that a clear image is formed even if the object distance changes. For this purpose, it is necessary to move at least one lens group.
　移動させるレンズ群の数は、少ないほうが好ましい。移動させるレンズ群の数を１つにすると、駆動機構を簡略化できる。本実施形態の対物光学系では、合焦時、第２レンズ群が移動する。移動するレンズ群の数が１つなので、合焦機構を簡略化できる。 It is preferable that the number of lens groups to be moved is small. If the number of lens groups to be moved is one, the driving mechanism can be simplified. In the objective optical system of the present embodiment, the second lens group moves during focusing. Since the number of moving lens groups is one, the focusing mechanism can be simplified.
　第２レンズ群の屈折力が大きいと、画角変動は大きくなる。本実施形態の対物光学系では、第２レンズ群は、正レンズと負レンズを含んでいる。そのため、第２レンズ群の屈折力が小さい。その結果、合焦の際の画角変動を小さくできる。 ) When the refractive power of the second lens group is large, the angle of view fluctuation increases. In the objective optical system of the present embodiment, the second lens group includes a positive lens and a negative lens. Therefore, the refractive power of the second lens group is small. As a result, it is possible to reduce the angle of view variation during focusing.
　本実施形態に係る対物光学系は、以下の条件式（１）を満足することが好ましい。
　－３．５＜ｆ2n／ｆ2p＜－１．５　　　（１）
　ここで、
　ｆ2pは、第２レンズ群の正レンズの焦点距離、
　ｆ2nは、第２レンズ群の負レンズの焦点距離、
である。 The objective optical system according to the present embodiment preferably satisfies the following conditional expression (1).
-3.5 <f2n / f2p <-1.5 (1)
here,
f2p is the focal length of the positive lens in the second lens group,
f2n is the focal length of the negative lens of the second lens group,
It is.
　値が条件式（１）の下限値を下回る場合、正レンズの屈折力が相対的に、負レンズの屈折力より大きくなり過ぎる。この場合、正レンズの影響を受ける収差、例えば、負の球面収差が生じる。そのため、結像性能が劣化する。 When the value is lower than the lower limit value of the conditional expression (1), the refractive power of the positive lens is relatively larger than the refractive power of the negative lens. In this case, an aberration affected by the positive lens, for example, a negative spherical aberration occurs. As a result, the imaging performance deteriorates.
　値が条件式（１）の上限値を上回る場合、負レンズの屈折力が相対的に、正レンズの屈折力より大きくなり過ぎる。この場合、負レンズの影響を受ける収差、例えば、正の球面収差が生じる。そのため、結像性能が劣化する。 When the value exceeds the upper limit value of the conditional expression (1), the refractive power of the negative lens is relatively larger than the refractive power of the positive lens. In this case, an aberration affected by the negative lens, for example, a positive spherical aberration occurs. As a result, the imaging performance deteriorates.
　本実施形態に係る対物光学系は、以下の条件式（２）を満足することが好ましい。
　５＜ｆ2／ｆfar＜８　　　（２）
　ここで、
　ｆ2は、第２レンズ群の焦点距離、
　ｆfarは、最遠距離物体に合焦したときの対物光学系全体の焦点距離、
である。 The objective optical system according to the present embodiment preferably satisfies the following conditional expression (2).
5 <f2 / ffar <8 (2)
here,
f2 is the focal length of the second lens group,
ffar is the focal length of the entire objective optical system when focusing on the farthest object,
It is.
　値が条件式（２）の下限値を下回る場合、第２レンズ群の焦点距離が短くなり過ぎる。この場合、第２レンズ群の屈折力が大きくなるので、合焦の際の画角変動が大きくなる。 When the value falls below the lower limit value of conditional expression (2), the focal length of the second lens group becomes too short. In this case, since the refractive power of the second lens group increases, the field angle fluctuation during focusing increases.
　値が条件式（２）の上限値を上回る場合、第２レンズ群の焦点距離が長くなり過ぎる。そのため、合焦範囲が狭くなる。合焦範囲は、第２レンズ群の移動量を大きくすることで広げられる。しかしながら、第２レンズ群の移動量を大きくすると、光学系の全長が長くなってしまう。 When the value exceeds the upper limit value of the conditional expression (2), the focal length of the second lens group becomes too long. Therefore, the focusing range is narrowed. The focusing range can be expanded by increasing the amount of movement of the second lens group. However, if the amount of movement of the second lens group is increased, the overall length of the optical system becomes longer.
　本実施形態に係る対物光学系では、第３レンズ群は、物体側から順番に、明るさ絞りと、第１のレンズ成分と、第２のレンズ成分と、第３のレンズ成分と、を含み、第１のレンズ成分は、正の屈折力を有する単レンズ、又は正の屈折力を有する接合レンズからなり、第２のレンズ成分は、負の屈折力を有する単レンズ、又は負の屈折力を有する接合レンズからなり、第３のレンズ成分は、正の屈折力を有する単レンズ、又は正の屈折力を有する接合レンズからなることが好ましい。 In the objective optical system according to the present embodiment, the third lens group includes, in order from the object side, an aperture stop, a first lens component, a second lens component, and a third lens component. The first lens component is a single lens having a positive refractive power or a cemented lens having a positive refractive power, and the second lens component is a single lens having a negative refractive power or a negative refractive power. It is preferable that the third lens component is a single lens having a positive refractive power or a cemented lens having a positive refractive power.
　第１のレンズ成分は正の屈折力を有し、第２のレンズ成分は負の屈折力を有し、第３のレンズ成分は正の屈折力を有する。よって、本実施形態に係る対物光学系では、第３レンズ群中に、屈折力の並びが、正の屈折力、負の屈折力、正の屈折力となる部分が形成される。 The first lens component has a positive refractive power, the second lens component has a negative refractive power, and the third lens component has a positive refractive power. Therefore, in the objective optical system according to the present embodiment, a portion in which the refractive power is arranged to have a positive refractive power, a negative refractive power, and a positive refractive power is formed in the third lens group.
　このような屈折力の並びは、トリプレットレンズにおける屈折力の並びと同じである。よって、本実施形態に係る対物光学系では、第３レンズ群中に、トリプレットレンズが配置されていると見なすことができる。 Such an arrangement of refractive power is the same as the arrangement of refractive power in a triplet lens. Therefore, in the objective optical system according to the present embodiment, it can be considered that a triplet lens is arranged in the third lens group.
　トリプレットレンズでは、小さいＦナンバーの確保と広い画角の確保とが両立できる。よって、本実施形態に係る対物光学系でも、小さいＦナンバーの確保と広い画角の確保とが両立できる。 The triplet lens can achieve both a small F-number and a wide angle of view. Therefore, the objective optical system according to the present embodiment can achieve both a small F number and a wide angle of view.
　本実施形態に係る対物光学系では、第１レンズ群は、物体側レンズと、像側レンズと、を有し、物体側レンズは、像側面が像側に凹の面であり、像側レンズは、物体側面が物体側に凹の面であり、像側レンズは、物体側レンズの隣に配置され、
　物体側レンズの像側面と像側レンズの物体側面とが向かい合っていることが好ましい。 In the objective optical system according to the present embodiment, the first lens group includes an object-side lens and an image-side lens, and the object-side lens is a surface whose image side surface is concave on the image side. Is an object side concave surface on the object side, the image side lens is arranged next to the object side lens,
It is preferable that the image side surface of the object side lens and the object side surface of the image side lens face each other.
　物体側レンズの像側面を像側に凹の面にすることで、物体側レンズの像側面は負の屈折力を持つ。像側レンズの物体側面を物体側に凹の面にすることで、像側レンズの物体側面は負の屈折力を持つ。よって、本実施形態に係る対物光学系では、第１レンズ群の負の屈折力を、２つのレンズ面に分担させることができる。そのため、諸収差の発生を抑制しつつ、広い画角を確保できる。 ¡By making the image side surface of the object side lens concave to the image side, the image side surface of the object side lens has negative refractive power. By making the object side surface of the image side lens concave on the object side, the object side surface of the image side lens has negative refractive power. Therefore, in the objective optical system according to the present embodiment, the negative refractive power of the first lens group can be shared by the two lens surfaces. Therefore, a wide angle of view can be secured while suppressing the occurrence of various aberrations.
　更に、物体側レンズの像側面と像側レンズの物体側面とは向かい合っている。そのため、像面湾曲や非点収差を低減させつつ、画角を広げられる。 Furthermore, the image side surface of the object side lens faces the object side surface of the image side lens. Therefore, the angle of view can be widened while reducing curvature of field and astigmatism.
　本実施形態に係る対物光学系では、第２レンズ群の正レンズと負レンズは、共に、物体側に凸面を向けたメニスカスレンズであることが好ましい。 In the objective optical system according to the present embodiment, it is preferable that both the positive lens and the negative lens of the second lens group are meniscus lenses having a convex surface facing the object side.
　このようにすることで、広角化に伴って発生する諸収差を、より良好に補正できる。 By doing in this way, various aberrations that occur with widening of the angle can be corrected more favorably.
　本実施形態に係る対物光学系では、第２レンズ群の正レンズは、第２レンズ群の負レンズよりも物体側に位置することが好ましい。 In the objective optical system according to the present embodiment, it is preferable that the positive lens of the second lens group is located closer to the object side than the negative lens of the second lens group.
　本実施形態に係る対物光学系では、第３レンズ群は、第４のレンズ成分と、第５のレンズ成分と、を有し、第４レンズ成分は、単レンズ、又は接合レンズからなり、第５のレンズ成分は接合レンズからなることが好ましい。 In the objective optical system according to the present embodiment, the third lens group includes a fourth lens component and a fifth lens component, and the fourth lens component includes a single lens or a cemented lens. The lens component 5 is preferably a cemented lens.
　本実施形態に係る対物光学系では、第３レンズ群の第４のレンズ成分と第５のレンズ成分は、像面の近くに配置されている。この位置では、軸上光束と軸外光束が分離した状態になっている。そのため、第４のレンズ成分と第５のレンズ成分とで、軸外収差を良好に補正できる。第５のレンズ成分は接合レンズからなるので、特に、倍率色収差を良好に補正できる。 In the objective optical system according to the present embodiment, the fourth lens component and the fifth lens component of the third lens group are disposed near the image plane. At this position, the on-axis light beam and the off-axis light beam are separated. Therefore, the off-axis aberration can be favorably corrected with the fourth lens component and the fifth lens component. Since the fifth lens component is composed of a cemented lens, the lateral chromatic aberration can be particularly favorably corrected.
　本実施形態に係る撮像装置は、上述の対物光学系と、撮像素子と、制御部と、演算部と、を備え、撮像素子は、対物光学系で生成された光学像を受光し、制御部は、第２レンズ群を、近点撮影位置と遠点撮影位置に移動させ、近点撮影位置における近点画像と遠点撮影位置における遠点画像とを、撮像素子で取得し、演算部は、近点画像と遠点画像とを合成することを特徴とする。 An imaging apparatus according to the present embodiment includes the above-described objective optical system, an imaging element, a control unit, and a calculation unit. The imaging element receives an optical image generated by the objective optical system, and receives a control unit. The second lens group is moved to the near point photographing position and the far point photographing position, the near point image at the near point photographing position and the far point image at the far point photographing position are acquired by the imaging device, , The near point image and the far point image are synthesized.
　このようにすることで、焦点深度が拡張された画像を生成できる。 This makes it possible to generate an image with an extended depth of focus.
　以下に、対物光学系の実施例を、図面に基づいて詳細に説明する。なお、この実施例によりこの発明が限定されるものではない。 Hereinafter, embodiments of the objective optical system will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.
　各実施例のレンズ断面図について説明する。（ａ）は遠距離物体合焦時のレンズ断面図、（ｂ）は近距離物体合焦時のレンズ断面図を示している。 The lens sectional view of each example will be described. (A) is a lens cross-sectional view when focusing on a long-distance object, and (b) is a lens cross-sectional view when focusing on a short-distance object.
　各実施例の収差図について説明する。（ａ）は遠距離物体合焦時の球面収差（ＳＡ）、（ｂ）は遠距離物体合焦時の非点収差（ＡＳ）、（ｃ）は遠距離物体合焦時の歪曲収差（ＤＴ）を示している。 An aberration diagram of each example will be described. (A) is spherical aberration (SA) when focusing on a long-distance object, (b) is astigmatism (AS) when focusing on a long-distance object, and (c) is distortion aberration (DT) when focusing on a long-distance object. ).
　各実施例の収差図について説明する。（ｄ）は近距離物体合焦時の球面収差（ＳＡ）、（ｅ）は近距離物体合焦時の非点収差（ＡＳ）、（ｆ）は近距離物体合焦時の歪曲収差（ＤＴ）を示している。 An aberration diagram of each example will be described. (D) Spherical aberration (SA) when focusing on a close object, (e) Astigmatism (AS) when focusing on a close object, and (f) Distortion aberration (DT) when focusing on a close object. ).
　第１レンズ群はＧ１、第２レンズ群はＧ２、第３レンズ群はＧ３、明るさ絞りはＳ、像面（撮像面）はＩで示してある。また、第３レンズ群Ｇ３と像面Ｉとの間に、平行平板ＣＧ１と、平行平板ＣＧ２と、が配置されている。 The first lens group is indicated by G1, the second lens group is indicated by G2, the third lens group is indicated by G3, the aperture stop is indicated by S, and the image surface (imaging surface) is indicated by I. In addition, a parallel plate CG1 and a parallel plate CG2 are disposed between the third lens group G3 and the image plane I.
　平行平板ＣＧ１は撮像素子のカバーガラス、平行平板ＣＧ２は封止ガラスである。以下の実施例では、平行平板ＣＧ２と像面Ｉとの間に、隙間が形成されている。しかしながら、この隙間は、必ずしも必要ではない。平行平板ＣＧ２の像側面に像面Ｉが位置していても良い。 The parallel plate CG1 is a cover glass of the image sensor, and the parallel plate CG2 is a sealing glass. In the following embodiments, a gap is formed between the parallel plate CG2 and the image plane I. However, this gap is not always necessary. The image plane I may be located on the image side surface of the parallel plate CG2.
　実施例１の対物光学系は、物体側から順に、負の屈折力を有する第１レンズ群Ｇ１と、正の屈折力を有する第２レンズ群Ｇ２と、正の屈折力を有する第３レンズ群Ｇ３と、で構成されている。 The objective optical system of Example 1 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3.
　第１レンズ群Ｇ１は、物体側が平面である平凹負レンズＬ１と、両凹負レンズＬ２と、物体側に凸面を向けた正メニスカスレンズＬ３と、を有する。 The first lens group G1 includes a plano-concave negative lens L1 having a plane on the object side, a biconcave negative lens L2, and a positive meniscus lens L3 having a convex surface facing the object side.
　第２レンズ群Ｇ２は、物体側に凸面を向けた正メニスカスレンズＬ４と、物体側に凸面を向けた負メニスカスレンズＬ５と、を有する。 The second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
　第３レンズ群Ｇ３は、両凸正レンズＬ６と、両凹負レンズＬ７と、像側に凸面を向けた正メニスカスレンズＬ８と、両凸正レンズＬ９と、像側に凸面を向けた負メニスカスレンズＬ１０と、両凸正レンズＬ１１と、像側に凸面を向けた負メニスカスレンズＬ１２と、を有する。ここで、両凸正レンズＬ９と負メニスカスレンズＬ１０とが、接合されている。両凸正レンズＬ１１と負メニスカスレンズＬ１２とが、接合されている。 The third lens group G3 includes a biconvex positive lens L6, a biconcave negative lens L7, a positive meniscus lens L8 having a convex surface facing the image side, a biconvex positive lens L9, and a negative meniscus having a convex surface facing the image side. It has a lens L10, a biconvex positive lens L11, and a negative meniscus lens L12 having a convex surface facing the image side. Here, the biconvex positive lens L9 and the negative meniscus lens L10 are cemented. The biconvex positive lens L11 and the negative meniscus lens L12 are cemented.
　開口絞りＳは、第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置されている。より詳しくは、開口絞りＳは、第３レンズ群Ｇ３の最も物体側に位置する面の近傍に配置されている。 The aperture stop S is disposed between the second lens group G2 and the third lens group G3. More specifically, the aperture stop S is disposed in the vicinity of the surface closest to the object side of the third lens group G3.
　合焦時、第２レンズ群Ｇ２が移動する。遠距離物体から近距離物体への合焦時、第２レンズ群Ｇ２は像側に移動する。開口絞りＳは、第３レンズ群Ｇ３と共に固定されている。 During focusing, the second lens group G2 moves. When focusing from a long-distance object to a short-distance object, the second lens group G2 moves to the image side. The aperture stop S is fixed together with the third lens group G3.
　第３レンズ群Ｇ３の像側には、平行平板ＣＧ１と、平行平板ＣＧ２と、が配置されている。 A parallel plate CG1 and a parallel plate CG2 are arranged on the image side of the third lens group G3.
　実施例２の対物光学系は、物体側から順に、負の屈折力を有する第１レンズ群Ｇ１と、正の屈折力を有する第２レンズ群Ｇ２と、正の屈折力を有する第３レンズ群Ｇ３と、で構成されている。 The objective optical system of Example 2 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3.
　第１レンズ群Ｇ１は、物体側に凸面を向けた負メニスカスレンズＬ１と、像側に凸面を向けた負メニスカスレンズＬ２と、像側に凸面を向けた負メニスカスレンズＬ３と、を有する。 The first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, a negative meniscus lens L2 having a convex surface facing the image side, and a negative meniscus lens L3 having a convex surface facing the image side.
　第２レンズ群Ｇ２は、物体側に凸面を向けた正メニスカスレンズＬ４と、物体側に凸面を向けた負メニスカスレンズＬ５と、を有する。 The second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
　第３レンズ群Ｇ３は、両凸正レンズＬ６と、像側に凸面を向けた負メニスカスレンズＬ７と、像側に凸面を向けた正メニスカスレンズＬ８と、両凸正レンズＬ９と、像側に凸面を向けた負メニスカスレンズＬ１０と、両凸正レンズＬ１１と、像側に凸面を向けた負メニスカスレンズＬ１２と、を有する。ここで、両凸正レンズＬ９と負メニスカスレンズＬ１０とが、接合されている。両凸正レンズＬ１１と負メニスカスレンズＬ１２とが、接合されている。 The third lens group G3 includes a biconvex positive lens L6, a negative meniscus lens L7 having a convex surface on the image side, a positive meniscus lens L8 having a convex surface on the image side, a biconvex positive lens L9, and an image side. It has a negative meniscus lens L10 having a convex surface, a biconvex positive lens L11, and a negative meniscus lens L12 having a convex surface facing the image side. Here, the biconvex positive lens L9 and the negative meniscus lens L10 are cemented. The biconvex positive lens L11 and the negative meniscus lens L12 are cemented.
　開口絞りＳは、第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置されている。より詳しくは、開口絞りＳは、第３レンズ群Ｇ３の最も物体側に位置する面の近傍に配置されている。 The aperture stop S is disposed between the second lens group G2 and the third lens group G3. More specifically, the aperture stop S is disposed in the vicinity of the surface closest to the object side of the third lens group G3.
　合焦時、第２レンズ群Ｇ２が移動する。遠距離物体から近距離物体への合焦時、第２レンズ群Ｇ２は像側に移動する。開口絞りＳは、第３レンズ群Ｇ３と共に固定されている。 During focusing, the second lens group G2 moves. When focusing from a long-distance object to a short-distance object, the second lens group G2 moves to the image side. The aperture stop S is fixed together with the third lens group G3.
　第３レンズ群Ｇ３の像側には、平行平板ＣＧ１と、平行平板ＣＧ２と、が配置されている。 A parallel plate CG1 and a parallel plate CG2 are arranged on the image side of the third lens group G3.
　実施例３の対物光学系は、物体側から順に、負の屈折力を有する第１レンズ群Ｇ１と、正の屈折力を有する第２レンズ群Ｇ２と、正の屈折力を有する第３レンズ群Ｇ３と、で構成されている。 The objective optical system of Example 3 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3.
　第１レンズ群Ｇ１は、物体側が平面である平凹負レンズＬ１と、両凹負レンズＬ２と、両凸正レンズＬ３と、を有する。ここで、両凹負レンズＬ２と両凸正レンズＬ３とが、接合されている。 The first lens group G1 includes a planoconcave negative lens L1, a biconcave negative lens L2, and a biconvex positive lens L3. Here, the biconcave negative lens L2 and the biconvex positive lens L3 are cemented.
　第２レンズ群Ｇ２は、物体側に凸面を向けた正メニスカスレンズＬ４と、物体側に凸面を向けた負メニスカスレンズＬ５と、を有する。 The second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
　第３レンズ群Ｇ３は、両凸正レンズＬ６と、両凹負レンズＬ７と、両凸正レンズＬ８と、両凸正レンズＬ９と、物体側に凸面を向けた負メニスカスレンズＬ１０と、両凸正レンズＬ１１と、像側に凸面を向けた負メニスカスレンズＬ１２と、を有する。ここで、凹負レンズＬ７と両凸正レンズＬ８とが、接合されている。両凸正レンズＬ１１と負メニスカスレンズＬ１２とが、接合されている。 The third lens group G3 includes a biconvex positive lens L6, a biconcave negative lens L7, a biconvex positive lens L8, a biconvex positive lens L9, a negative meniscus lens L10 having a convex surface facing the object side, and a biconvex lens. A positive lens L11 and a negative meniscus lens L12 having a convex surface facing the image side. Here, the concave negative lens L7 and the biconvex positive lens L8 are cemented. The biconvex positive lens L11 and the negative meniscus lens L12 are cemented.
　開口絞りＳは、第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置されている。より詳しくは、開口絞りＳは、第３レンズ群Ｇ３の最も物体側に位置する面の近傍に配置されている。 The aperture stop S is disposed between the second lens group G2 and the third lens group G3. More specifically, the aperture stop S is disposed in the vicinity of the surface closest to the object side of the third lens group G3.
　合焦時、第２レンズ群Ｇ２が移動する。遠距離物体から近距離物体への合焦時、第２レンズ群Ｇ２は像側に移動する。開口絞りＳは、第３レンズ群Ｇ３と共に固定されている。 During focusing, the second lens group G2 moves. When focusing from a long-distance object to a short-distance object, the second lens group G2 moves to the image side. The aperture stop S is fixed together with the third lens group G3.
　第３レンズ群Ｇ３の像側には、平行平板ＣＧ１と、平行平板ＣＧ２と、が配置されている。 A parallel plate CG1 and a parallel plate CG2 are arranged on the image side of the third lens group G3.
　実施例４の対物光学系は、物体側から順に、負の屈折力を有する第１レンズ群Ｇ１と、正の屈折力を有する第２レンズ群Ｇ２と、正の屈折力を有する第３レンズ群Ｇ３と、で構成されている。 The objective optical system of Example 4 includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a positive refractive power. G3.
　第１レンズ群Ｇ１は、物体側が平面である平凹負レンズＬ１と、像側に凸面を向けた負メニスカスレンズＬ２と、物体側に凸面を向けた正メニスカスレンズＬ３と、を有する。 The first lens group G1 includes a plano-concave negative lens L1 having a flat surface on the object side, a negative meniscus lens L2 having a convex surface facing the image side, and a positive meniscus lens L3 having a convex surface facing the object side.
　第２レンズ群Ｇ２は、物体側に凸面を向けた正メニスカスレンズＬ４と、物体側に凸面を向けた負メニスカスレンズＬ５と、を有する。 The second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.
　第３レンズ群Ｇ３は、両凸正レンズＬ６と、両凹負レンズＬ７と、両凸正レンズＬ８と、両凸正レンズＬ９と、両凸正レンズＬ１０と、像側に凸面を向けた負メニスカスレンズＬ１１と、を有する。ここで、両凸正レンズＬ１０と負メニスカスレンズＬ１１とが、接合されている。 The third lens group G3 includes a biconvex positive lens L6, a biconcave negative lens L7, a biconvex positive lens L8, a biconvex positive lens L9, a biconvex positive lens L10, and a negative with a convex surface facing the image side. Meniscus lens L11. Here, the biconvex positive lens L10 and the negative meniscus lens L11 are cemented.
　開口絞りＳは、第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置されている。より詳しくは、開口絞りＳは、第３レンズ群Ｇ３の最も物体側に位置する面の近傍に配置されている。 The aperture stop S is disposed between the second lens group G2 and the third lens group G3. More specifically, the aperture stop S is disposed in the vicinity of the surface closest to the object side of the third lens group G3.
　合焦時、第２レンズ群Ｇ２が移動する。遠距離物体から近距離物体への合焦時、第２レンズ群Ｇ２は像側に移動する。開口絞りＳは、第３レンズ群Ｇ３と共に固定されている。 During focusing, the second lens group G2 moves. When focusing from a long-distance object to a short-distance object, the second lens group G2 moves to the image side. The aperture stop S is fixed together with the third lens group G3.
　第３レンズ群Ｇ３の像側には、平行平板ＣＧ１と、平行平板ＣＧ２と、が配置されている。 A parallel plate CG1 and a parallel plate CG2 are arranged on the image side of the third lens group G3.
　以下に、上記各実施例の数値データを示す。面データにおいて、ｒは各レンズ面の曲率半径、ｄは各レンズ面間の間隔、ｎｅは各レンズのｅ線の屈折率、νｄは各レンズのアッベ数である。 The numerical data of each of the above examples is shown below. In the surface data, r is the radius of curvature of each lens surface, d is the distance between the lens surfaces, ne is the refractive index of the e-line of each lens, and νd is the Abbe number of each lens.
　また、各種データにおいて、遠距離は遠距離物体合焦時、近距離は近距離物体合焦時、ＯＢは物体距離、ｆは全系の焦点距離、ＦＮＯ．はＦナンバー、ωは半画角、ＩＨは像高である。 Also, in various data, the long distance is when the long distance object is focused, the short distance is when the short distance object is focused, OB is the object distance, f is the focal length of the entire system, FNO. Is the F number, ω is the half field angle, and IH is the image height.
　また、各群焦点距離において、ｆ１、ｆ２…は各レンズ群の焦点距離である。 In each group focal length, f1, f2,... Are focal lengths of the lens groups.
数値実施例１
単位  ｍｍ
 
面データ
面番号      r          d          ne         νd
物面       ∞        23
1          ∞         0.35      1.888146     40.76
2         1.27161     0.7
3        -2.4432      0.4       1.518251     64.14
4         7.47418     0.1
5         2.33831     0.7481    1.820167     46.62
6         5.58761     可変
7         1.81045     0.45      1.489147     70.23
8         6.94666     0.1
9         2.34144     0.25      1.489147     70.23
10        1.4923      可変
11(絞り)   ∞         0.1
12        2.05        0.7       1.732336     54.68
13       -4.38925     0.15
14       -1.53741     1.2119    1.820167     46.62
15       13.07404     0.1
16       -9.64112     0.7       1.732336     54.68
17       -2.37619     0.1
18        4.05447     1.4       1.498455     81.54
19       -2.2         0.4       1.888146     40.76
20       -3.21743     0.1
21        4.05447     1.4       1.498455     81.54
22       -2.2         0.4       1.855041     23.78
23      -29.72887     0.5892
24         ∞         0.8       1.518251     64.14
25         ∞         0.7       1.613503     50.40
26         ∞         0.100
像面       ∞
 
各種データ
          遠距離       近距離
ＯＢ       23            2.8
ｆ          1.0703       1.0498
ＦＮＯ．    3.5
２ω      159.9        160.0
ＩＨ        1.14
 
d6          0.2          0.9343
d10         0.9343       0.2
 
各群焦点距離
f1=-1.2761     f2=8.3042     f3=2.7438 Numerical example 1
Unit mm

Surface data surface number r d ne νd
Surface ∞ 23
1 ∞ 0.35 1.888146 40.76
2 1.27161 0.7
3 -2.4432 0.4 1.518251 64.14
4 7.47418 0.1
5 2.33831 0.7481 1.820167 46.62
6 5.58761 Variable
7 1.81045 0.45 1.489147 70.23
8 6.94666 0.1
9 2.34144 0.25 1.489147 70.23
10 1.4923 Variable
11 (Aperture) ∞ 0.1
12 2.05 0.7 1.732336 54.68
13 -4.38925 0.15
14 -1.53741 1.2119 1.820167 46.62
15 13.07404 0.1
16 -9.64112 0.7 1.732336 54.68
17 -2.37619 0.1
18 4.05447 1.4 1.498455 81.54
19 -2.2 0.4 1.888146 40.76
20 -3.21743 0.1
21 4.05447 1.4 1.498455 81.54
22 -2.2 0.4 1.855041 23.78
23 -29.72887 0.5892
24 ∞ 0.8 1.518251 64.14
25 ∞ 0.7 1.613503 50.40
26 ∞ 0.100
Image plane ∞

Various data Long distance Short distance OB 23 2.8
f 1.0703 1.0498
FNO. 3.5
2ω 159.9 160.0
IH 1.14

d6 0.2 0.9343
d10 0.9343 0.2

Each group focal length
f1 = -1.2761 f2 = 8.3042 f3 = 2.7438
数値実施例２
単位  ｍｍ
 
面データ
面番号      r          d          ne         νd
物面       ∞        23
1        10.1792      0.37      1.888146     40.76
2         1.2         0.75
3        -1.8402      0.4       1.518251     64.14
4        -7.5232      0.0969
5        -2.8899      0.4774    1.820167     46.62
6        -3.2906      可変
7         1.6         0.4       1.489147     70.23
8        54.6520      0.1859
9         4.6766      0.2       1.489147     70.23
10        1.5679      可変
11(絞り)   ∞         0.1
12        2.3173      0.7       1.654251     58.55
13       -3.4084      0.15
14       -1.4461      0.4513    1.820167     46.62
15       -2.8         0.4338
16       -4.8196      1         1.791961     47.37
17       -2.7602      0.1444
18       17.1786      1.2       1.498455     81.54
19       -2.1129      0.45      1.761671     27.51
20       -4.0300      0.1
21        3.4556      1.4       1.498455     81.54
22       -2.1         0.4       1.855041     23.78
23      -11.3110      0.4
24         ∞         0.8       1.518251     64.14
25         ∞         0.7       1.613503     50.40
26         ∞         0.1
像面       ∞
 
          遠距離       近距離
ＯＢ       23            3
ｆ          0.9938       0.9816
ＦＮＯ．    4.0
２ω      165.1        165.0
ＩＨ        1.14
 
d6          0.3          0.8201
d10         0.8201       0.3
 
各群焦点距離
f1=-1.1102     f2=7.4148     f3=2.7386 Numerical example 2
Unit mm

Surface data surface number r d ne νd
Surface ∞ 23
1 10.1792 0.37 1.888146 40.76
2 1.2 0.75
3 -1.8402 0.4 1.518251 64.14
4 -7.5232 0.0969
5 -2.8899 0.4774 1.820167 46.62
6 -3.2906 Variable
7 1.6 0.4 1.489147 70.23
8 54.6520 0.1859
9 4.6766 0.2 1.489147 70.23
10 1.5679 Variable
11 (Aperture) ∞ 0.1
12 2.3173 0.7 1.654251 58.55
13 -3.4084 0.15
14 -1.4461 0.4513 1.820167 46.62
15 -2.8 0.4338
16 -4.8196 1 1.791961 47.37
17 -2.7602 0.1444
18 17.1786 1.2 1.498455 81.54
19 -2.1129 0.45 1.761671 27.51
20 -4.0300 0.1
21 3.4556 1.4 1.498455 81.54
22 -2.1 0.4 1.855041 23.78
23 -11.3110 0.4
24 ∞ 0.8 1.518251 64.14
25 ∞ 0.7 1.613503 50.40
26 ∞ 0.1
Image plane ∞

Long distance Short distance OB 23 3
f 0.9938 0.9816
FNO. 4.0
2ω 165.1 165.0
IH 1.14

d6 0.3 0.8201
d10 0.8201 0.3

Each group focal length
f1 = -1.1102 f2 = 7.4148 f3 = 2.7386
数値実施例３
単位  ｍｍ
 
面データ
面番号      r          d          ne         νd
物面       ∞        23
1          ∞         0.37      1.888146     40.76
2         1.3976      0.8554
3        -2.7332      0.3       1.732336     54.68
4         6           0.85      1.816434     22.76
5        -8.5586      可変
6         1.7056      0.45      1.654251     58.55
7         3.3510      0.3570
8         1.5681      0.3       1.654251     58.55
9         1.2706      可変
10(絞り)   ∞         0.1113
11        2.2510      0.7       1.776208     49.60
12       -4.3226      0.15
13       -1.4680      0.4620    1.743413     32.26
14        3.0621      1.2       1.520326     58.90
15       -2.55        0.1
16        8.1119      0.5094    1.758437     52.32
17       -5.5502      0.3449
18        3.6697      0.5431    1.810775     40.92
19        1.8654      0.1363
20        2.8910      1.3       1.654251     58.55
21       -3.2963      0.4       1.934291     18.90
22       -7.9998      0.4132
23         ∞         0.8       1.518251     64.14
24         ∞         0.7       1.613503     50.40
25         ∞         0.1036
像面       ∞
 
各種データ
          遠距離       近距離
ＯＢ       23            2.6
ｆ          1.0648       1.0431
ＦＮＯ．    3.8
２ω      160.5        160.0
ＩＨ        1.14
 
d5          0.3510       0.8675
d9          0.8429       0.3267
 
各群焦点距離
f1=-1.2277      f2=5.5565    f3=2.7446 Numerical Example 3
Unit mm

Surface data surface number r d ne νd
Surface ∞ 23
1 ∞ 0.37 1.888146 40.76
2 1.3976 0.8554
3 -2.7332 0.3 1.732336 54.68
4 6 0.85 1.816434 22.76
5 -8.5586 Variable
6 1.7056 0.45 1.654251 58.55
7 3.3510 0.3570
8 1.5681 0.3 1.654251 58.55
9 1.2706 Variable
10 (Aperture) ∞ 0.1113
11 2.2510 0.7 1.776208 49.60
12 -4.3226 0.15
13 -1.4680 0.4620 1.743413 32.26
14 3.0621 1.2 1.520326 58.90
15 -2.55 0.1
16 8.1119 0.5094 1.758437 52.32
17 -5.5502 0.3449
18 3.6697 0.5431 1.810775 40.92
19 1.8654 0.1363
20 2.8910 1.3 1.654251 58.55
21 -3.2963 0.4 1.934291 18.90
22 -7.9998 0.4132
23 ∞ 0.8 1.518251 64.14
24 ∞ 0.7 1.613503 50.40
25 ∞ 0.1036
Image plane ∞

Various data Long distance Short distance OB 23 2.6
f 1.0648 1.0431
FNO. 3.8
2ω 160.5 160.0
IH 1.14

d5 0.3510 0.8675
d9 0.8429 0.3267

Each group focal length
f1 = -1.2277 f2 = 5.5565 f3 = 2.7446
数値実施例４
単位  ｍｍ
 
面データ
面番号      r          d          ne         νd
物面       ∞        23
1          ∞         0.37      1.888146     40.76
2         1.2842      0.8
3        -1.7069      0.4       1.542121     59.46
4        -3.2590      0.2
5         3.7402      1.0095    1.820167     46.62
6         8.6632      可変
7         1.55        0.45      1.489147     70.23
8         3.7430      0.12
9         1.4303      0.25      1.489147     70.23
10        1.0941      可変
11(絞り)   ∞         0.1
12        2.2663      0.7       1.732336     54.68
13       -4.8453      0.15
14       -1.7718      0.8487    1.810775     40.92
15        3.3169      0.1
16        3.7965      0.7       1.732336     54.68
17       -5.8677      0.1
18      547.2814      1.6       1.654251     58.55
19       -3.3119      0.1
20        2.8         1.65      1.498455     81.54
21       -2.4         0.4       1.855041     23.78
22      -37.312       0.6557
23         ∞         0.8       1.518251     64.14
24         ∞         0.7       1.613503     50.40
25         ∞         0.1
像面       ∞
 
          遠距離       近距離
ＯＢ       23            2.8
ｆ          1.2016       1.1484
ＦＮＯ．    4.0
２ω      154.5        160.0
ＩＨ        1.14
 
d6          0.3          0.996
d10         0.996        0.3
 
各群焦点距離
f1=-1.5522     f2=7.0330     f3=2.9333 Numerical Example 4
Unit mm

Surface data surface number r d ne νd
Surface ∞ 23
1 ∞ 0.37 1.888146 40.76
2 1.2842 0.8
3 -1.7069 0.4 1.542121 59.46
4 -3.2590 0.2
5 3.7402 1.0095 1.820167 46.62
6 8.6632 Variable
7 1.55 0.45 1.489147 70.23
8 3.7430 0.12
9 1.4303 0.25 1.489147 70.23
10 1.0941 Variable
11 (Aperture) ∞ 0.1
12 2.2663 0.7 1.732336 54.68
13 -4.8453 0.15
14 -1.7718 0.8487 1.810775 40.92
15 3.3 169 0.1
16 3.7965 0.7 1.732336 54.68
17 -5.8677 0.1
18 547.2814 1.6 1.654251 58.55
19 -3.3119 0.1
20 2.8 1.65 1.498455 81.54
21 -2.4 0.4 1.855041 23.78
22 -37.312 0.6557
23 ∞ 0.8 1.518251 64.14
24 ∞ 0.7 1.613503 50.40
25 ∞ 0.1
Image plane ∞

Long distance Short distance OB 23 2.8
f 1.2016 1.1484
FNO. 4.0
2ω 154.5 160.0
IH 1.14

d6 0.3 0.996
d10 0.996 0.3

Each group focal length
f1 = -1.5522 f2 = 7.0330 f3 = 2.9333
　次に、各実施例における条件式の値を以下に掲げる。
            実施例１    実施例２    実施例３    実施例４
f2n/f2p     -1.914     -1.466       -3.553      -2.484
f2/ffar      7.76       7.46         5.22        5.85 Next, the values of the conditional expressions in each example are listed below.
Example 1 Example 2 Example 3 Example 4
f2n / f2p -1.914 -1.466 -3.553 -2.484
f2 / ffar 7.76 7.46 5.22 5.85
　以上のように、本発明は、合焦の際の画角変動が小さく、諸収差が良好に補正された対物光学系及びそれを用いた撮像装置に適している。 As described above, the present invention is suitable for an objective optical system in which fluctuations in the angle of view at the time of focusing are small and various aberrations are well corrected, and an imaging apparatus using the objective optical system.
　Ｇ１　第１レンズ群
　Ｇ２　第２レンズ群
　Ｇ３　第３レンズ群
　Ｓ　明るさ開口絞り
　Ｉ　像面
　ＣＧ１、ＣＧ２　平行平板 G1 First lens group G2 Second lens group G3 Third lens group S Brightness aperture stop I Image plane CG1, CG2 Parallel flat plate

Claims (8)

  1. 　物体側から順に、
    　負の屈折力を有する第１レンズ群と、
    　第２レンズ群と、
    　明るさ絞りと、
    　正の屈折力を有する第３レンズ群と、からなり、
    　合焦時、前記第２レンズ群は光軸に沿って移動し、
    　前記第２レンズ群は、正レンズと、負レンズと、からなることを特徴とする対物光学系。     From the object side,
    A first lens group having negative refractive power;
    A second lens group;
    The aperture stop,
    A third lens group having a positive refractive power,
    During focusing, the second lens group moves along the optical axis,
    The objective lens system, wherein the second lens group includes a positive lens and a negative lens.
  2. 　以下の条件式（１）を満足することを特徴とする請求項１に記載の対物光学系。
    　－３．５＜ｆ2n／ｆ2p＜－１．５　　　（１）
    　ここで、
    　ｆ2pは、前記第２レンズ群の前記正レンズの焦点距離、
    　ｆ2nは、前記第２レンズ群の前記負レンズの焦点距離、
    である。     The objective optical system according to claim 1, wherein the following conditional expression (1) is satisfied.
    -3.5 <f2n / f2p <-1.5 (1)
    here,
    f2p is the focal length of the positive lens of the second lens group,
    f2n is a focal length of the negative lens of the second lens group,
    It is.
  3. 　以下の条件式（２）を満足することを特徴とする請求項１に記載の対物光学系。
    　５＜ｆ2／ｆfar＜８　　　（２）
    　ここで、
    　ｆ2は、前記第２レンズ群の焦点距離、
    　ｆfarは、最遠距離物体に合焦したときの前記対物光学系全体の焦点距離、
    である。     The objective optical system according to claim 1, wherein the following conditional expression (2) is satisfied.
    5 <f2 / ffar <8 (2)
    here,
    f2 is the focal length of the second lens group,
    ffar is the focal length of the entire objective optical system when focusing on the farthest distance object,
    It is.
  4. 　前記第３レンズ群は、物体側から順番に、明るさ絞りと、第１のレンズ成分と、第２のレンズ成分と、第３のレンズ成分と、を含み、
    　前記第１のレンズ成分は、正の屈折力を有する単レンズ、又は正の屈折力を有する接合レンズからなり、
    　前記第２のレンズ成分は、負の屈折力を有する単レンズ、又は負の屈折力を有する接合レンズからなり、
    　前記第３のレンズ成分は、正の屈折力を有する単レンズ、又は正の屈折力を有する接合レンズからなることを特徴とする請求項１に記載の対物光学系。     The third lens group includes, in order from the object side, an aperture stop, a first lens component, a second lens component, and a third lens component;
    The first lens component includes a single lens having a positive refractive power or a cemented lens having a positive refractive power,
    The second lens component comprises a single lens having negative refractive power or a cemented lens having negative refractive power,
    The objective optical system according to claim 1, wherein the third lens component is a single lens having a positive refractive power or a cemented lens having a positive refractive power.
  5. 　前記第１レンズ群は、物体側レンズと、像側レンズと、を有し、
    　前記物体側レンズは、像側面が像側に凹の面であり、
    　前記像側レンズは、物体側面が物体側に凹の面であり、
    　前記像側レンズは、前記物体側レンズの隣に配置され、
    　前記物体側レンズの像側面と前記像側レンズの物体側面とが向かい合っていることを特徴とする請求項１に記載の対物光学系。     The first lens group includes an object side lens and an image side lens,
    The object side lens is a surface whose image side surface is concave on the image side,
    The image side lens is a surface in which the object side surface is concave on the object side,
    The image side lens is disposed next to the object side lens,
    The objective optical system according to claim 1, wherein an image side surface of the object side lens faces an object side surface of the image side lens.
  6. 　前記第２レンズ群の前記正レンズと前記負レンズは、共に、物体側に凸面を向けたメニスカスレンズであることを特徴とする請求項１に記載の対物光学系。 2. The objective optical system according to claim 1, wherein both the positive lens and the negative lens of the second lens group are meniscus lenses having a convex surface directed toward the object side.
  7. 　前記第２レンズ群の前記正レンズは、前記第２レンズ群の前記負レンズよりも物体側に位置することを特徴とする請求項１に記載の対物光学系。 2. The objective optical system according to claim 1, wherein the positive lens of the second lens group is located closer to the object side than the negative lens of the second lens group.
  8. 　請求項１に記載の対物光学系と、撮像素子と、制御部と、演算部と、を備え、
    　前記撮像素子は、前記対物光学系で生成された光学像を受光し、
    　前記制御部は、前記第２レンズ群を、近点撮影位置と遠点撮影位置に移動させ、
    　前記近点撮影位置における近点画像と前記遠点撮影位置における遠点画像とを、前記撮像素子で取得し、
    　前記演算部は、前記近点画像と前記遠点画像とを合成することを特徴とする撮像装置。     The objective optical system according to claim 1, an image sensor, a control unit, and a calculation unit,
    The image sensor receives an optical image generated by the objective optical system,
    The control unit moves the second lens group to a near point photographing position and a far point photographing position,
    The near point image at the near point photographing position and the far point image at the far point photographing position are acquired by the imaging element,
    The said calculating part synthesize | combines the said near point image and the said far point image, The imaging device characterized by the above-mentioned.
PCT/JP2018/016935 2018-04-26 2018-04-26 Objective optical system and imaging device using same WO2019207699A1 (en)

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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08304704A (en) * 1995-03-08 1996-11-22 Nikon Corp Zoom lens
JP2000131606A (en) * 1998-10-22 2000-05-12 Olympus Optical Co Ltd Wide angle lens having long back focus
JP2007094174A (en) * 2005-09-29 2007-04-12 Nikon Corp Zoom lens
JP2008233284A (en) * 2007-03-19 2008-10-02 Nikon Corp Zoom lens, optical device, and imaging method
JP2011107267A (en) * 2009-11-13 2011-06-02 Nikon Corp Lens system, optical apparatus, method for manufacturing the lens system
JP2011242520A (en) * 2010-05-17 2011-12-01 Olympus Imaging Corp Imaging optical system and imaging apparatus comprising the same
WO2013027459A1 (en) * 2011-08-24 2013-02-28 オリンパスメディカルシステムズ株式会社 Image capture device and iamge capture device system
JP2014056133A (en) * 2012-09-13 2014-03-27 Canon Inc Zoom lens and image capturing device having the same
WO2014088104A1 (en) * 2012-12-07 2014-06-12 オリンパス株式会社 Objective lens and observation device equipped with same
WO2014129089A1 (en) * 2013-02-22 2014-08-28 オリンパスメディカルシステムズ株式会社 Endoscope objective optical system, and imaging device

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08304704A (en) * 1995-03-08 1996-11-22 Nikon Corp Zoom lens
JP2000131606A (en) * 1998-10-22 2000-05-12 Olympus Optical Co Ltd Wide angle lens having long back focus
JP2007094174A (en) * 2005-09-29 2007-04-12 Nikon Corp Zoom lens
JP2008233284A (en) * 2007-03-19 2008-10-02 Nikon Corp Zoom lens, optical device, and imaging method
JP2011107267A (en) * 2009-11-13 2011-06-02 Nikon Corp Lens system, optical apparatus, method for manufacturing the lens system
JP2011242520A (en) * 2010-05-17 2011-12-01 Olympus Imaging Corp Imaging optical system and imaging apparatus comprising the same
WO2013027459A1 (en) * 2011-08-24 2013-02-28 オリンパスメディカルシステムズ株式会社 Image capture device and iamge capture device system
JP2014056133A (en) * 2012-09-13 2014-03-27 Canon Inc Zoom lens and image capturing device having the same
WO2014088104A1 (en) * 2012-12-07 2014-06-12 オリンパス株式会社 Objective lens and observation device equipped with same
WO2014129089A1 (en) * 2013-02-22 2014-08-28 オリンパスメディカルシステムズ株式会社 Endoscope objective optical system, and imaging device

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