JP2009053330A

JP2009053330A - Optical system

Info

Publication number: JP2009053330A
Application number: JP2007218345A
Authority: JP
Inventors: Kokichi Kenno; 孝吉研野
Original assignee: Olympus Corp
Current assignee: Olympus Corp
Priority date: 2007-08-24
Filing date: 2007-08-24
Publication date: 2009-03-12

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical system capable of photographing a wide observation field angle out of an axis in a compact and simple composition in a reflection optical system and a catadioptric system. <P>SOLUTION: A rotary symmetric optical system to an optical axis O-O' includes reflection faces 1, 3 of two opposite faces. Each of the reflection faces 1, 3 has openings 2, 4 in a center part including the optical axis. In the optical system wherein a light flux from an object out of the optical axis incident between the reflection faces of two faces through the opening 2 of the object side reflection face 1 is reflected in order of the image plane side reflection face 3 and the object side reflection face 1 and image-formed on an image plane 5 by outgoing from between the reflection faces of the two faces through the opening 4 of the image plane side reflection face 3, a light flux incident through the opening 2 of the object side reflection face 1 and a light flux reflected on the object side reflection face 1 and outgoing through the opening 4 of the image plane side reflection face 3 are intersected on only one side of the optical axis. An intermediate image 21 of the object is image-formed between the reflection faces 1, 3 of the two faces of only one time. At least one face of the reflection faces 1, 3 comprises a discontinuous rotary symmetric curved face on the optical axis. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

本発明は光学系に関し、特に、反射光学系、反射屈折光学系であって、小型で簡単な構成で軸外の広い観察画角を撮像可能な結像光学系に関するものである。 The present invention relates to an optical system, and more particularly to an imaging optical system that is a reflective optical system and a catadioptric optical system and can capture a wide off-axis observation angle of view with a small and simple configuration.

従来、２面の球面鏡、放物面鏡、楕円面鏡を組み合わせて対物系としたりリレー光学系とすることはよく知られており、その応用例もある。 Conventionally, it is well known that an objective system or a relay optical system is formed by combining two spherical mirrors, a parabolic mirror, and an ellipsoidal mirror, and there is an application example thereof.

特許文献１に記載のものは、２枚の中央に開口を持つ凹面球面鏡を対向させ、その２つの反射面の間に２枚のレンズを配置してリレー光学系とするものである。 Patent Document 1 discloses a relay optical system in which two concave spherical mirrors having an opening at the center are opposed to each other and two lenses are arranged between the two reflecting surfaces.

また、特許文献２に記載のものは、裏面鏡からなる２枚の中央に開口を持つ凹面球面鏡を対向させてなる対物系である。
特開２００５−２３３９７９号公報特表２００７−５１４１７９号公報 Further, the device described in Patent Document 2 is an objective system in which two concave spherical mirrors having an opening at the center of two back mirrors are opposed to each other.
Japanese Patent Laid-Open No. 2005-2331979 Special table 2007-514179 gazette

しかし、特許文献１〜２等で知られている反射屈折光学系は、何れも軸上像を結像するためのものであり、軸外の広い画角の像を結像するものではなく、さらに大型になるものである。 However, the catadioptric optical systems known from Patent Documents 1 and 2 are all for forming an on-axis image, not an image with a wide off-axis image, It will be even larger.

本発明は従来技術のこのような状況に鑑みてなされたものであり、その目的は、反射光学系、反射屈折光学系であって、小型で簡単な構成で軸外の広い観察画角を撮像可能な光学系を提供することである。 The present invention has been made in view of such a situation in the prior art, and an object thereof is a reflection optical system and a catadioptric optical system, which captures a wide off-axis observation angle of view with a small and simple configuration. It is to provide a possible optical system.

上記目的を達成する本発明の光学系は、光軸に対して回転対称な光学系であって、対向する２面の反射面を備え、前記反射面は各々は光軸を含む中心部に開口を備え、物体側反射面の開口を経て２面の反射面間に入射した光軸外の物体からの光束は、像面側反射面、前記物体側反射面の順に反射して、前記像面側反射面の開口を経て２面の反射面間から出て像面に結像する光学系であって、前記物体側反射面の開口を経て入射する光束と前記物体側反射面で反射されて前記像面側反射面の開口を経て出る光束とが光軸の片側のみで交差する光学系において、
物体の中間像を１回のみ前記２面の反射面の間に結像し、かつ、前記反射面の中少なくとも１面は光軸上で不連続な回転対称な曲面からなることを特徴とするものである。 An optical system of the present invention that achieves the above object is an optical system that is rotationally symmetric with respect to an optical axis, and includes two opposing reflecting surfaces, each of which opens at a central portion including the optical axis. A light beam from an object outside the optical axis that is incident between the two reflecting surfaces through the opening of the object-side reflecting surface is reflected in the order of the image-side reflecting surface and the object-side reflecting surface, and the image surface An optical system for forming an image on an image surface through an opening on the side reflecting surface and forming an image on an image surface, and is reflected by the light beam incident through the opening on the object side reflecting surface and the object side reflecting surface In the optical system in which the light beam emitted through the aperture of the image plane side reflecting surface intersects only on one side of the optical axis,
An intermediate image of an object is formed only once between the two reflecting surfaces, and at least one of the reflecting surfaces is formed of a rotationally symmetric curved surface that is discontinuous on the optical axis. Is.

この場合、前記２面の反射面間が透明媒質で満たされ、前記物体側反射面の開口近傍に回転対称な入射面、前記像面側反射面の開口近傍に回転対称な射出面を備えていることが望ましい。 In this case, a space between the two reflecting surfaces is filled with a transparent medium, and a rotationally symmetric incident surface is provided near the opening of the object-side reflecting surface, and a rotationally symmetric exit surface is provided near the opening of the image-side reflecting surface. It is desirable.

また、前記入射面、前記射出面の一方がそれぞれ前記物体側反射面、前記像面側反射面を構成する曲面と同一位置同一形状の曲面からなっていてもよい。 Further, one of the incident surface and the exit surface may be a curved surface having the same position and shape as the curved surface constituting the object-side reflecting surface and the image-side reflecting surface, respectively.

また、前記光軸上で不連続な回転対称な曲面がトーリック面、あるいは、光軸を含む平面上で任意形状の曲線を光軸の周りで回転させて形成される回転自由曲面から構成することができる。 Further, the rotationally symmetric curved surface that is discontinuous on the optical axis is a toric surface or a rotationally free curved surface that is formed by rotating an arbitrary shape curve around the optical axis on a plane including the optical axis. Can do.

また、前記光軸上で不連続な回転対称な曲面が光軸を含む平面上で奇数次項を含む任意形状の曲線を光軸の周りで回転させて形成される回転自由曲面からなることが望ましい。 Further, it is desirable that the rotationally symmetric curved surface that is discontinuous on the optical axis is a free-form curved surface formed by rotating an arbitrary-shaped curve including an odd-order term on the plane including the optical axis around the optical axis. .

また、前記物体側反射面の開口前方の光軸近傍の物体からの光束が、前記入射面、前記射出面の順に通過して前記像面に結像されることもできる。 Further, a light beam from an object in the vicinity of the optical axis in front of the opening of the object-side reflecting surface may pass through the incident surface and the exit surface in this order to form an image on the image surface.

以上の本発明によると、小型で簡単な構成で軸外の広い観察画角を撮像可能な光学系を得ることができる。 According to the present invention described above, an optical system capable of capturing a wide off-axis observation angle of view with a small and simple configuration can be obtained.

以下、本発明の光学系を実施例に基づいて説明する。 The optical system of the present invention will be described below based on examples.

図１は、本発明の実施例１の光学系の光軸を含み光路を示す断面図である。 FIG. 1 is a sectional view showing an optical path including the optical axis of the optical system according to the first embodiment of the present invention.

本発明の光学系１０は、光軸Ｏ−Ｏ’を中心として回転対称な光学系である。そして、対向する２面の反射面１、３を備えており、反射面１、３各々は光軸Ｏ−Ｏ’を含む中心部にそれぞれ開口２、４を備えている。このように、本発明の光学系１０は、光軸Ｏ−Ｏ’を中心として回転対称であるので、製作性が良い。 The optical system 10 of the present invention is an optical system that is rotationally symmetric about the optical axis O-O ′. Then, two opposing reflecting surfaces 1 and 3 are provided, and each of the reflecting surfaces 1 and 3 is provided with an opening 2 and 4 at the center including the optical axis O-O ', respectively. Thus, since the optical system 10 of the present invention is rotationally symmetric about the optical axis O-O ', the manufacturability is good.

この光学系１０は、光軸Ｏ−Ｏ’の外の物体からの光束を入射させて像面５に結像するものであり、構成が上記のように回転対称であるため、光軸Ｏ−Ｏ’の外の光軸Ｏ−Ｏ’を中心とする３６０°全方位の軸外の物体の像を像面５に円環状に結像する。図１は特定方位の断面図であり、その方位における最内画角の光束を１１_i、最外画角の光束を１１_oとしている。 This optical system 10 makes a light beam from an object outside the optical axis OO ′ incident and forms an image on the image plane 5, and since the configuration is rotationally symmetric as described above, the optical axis O−. An image of an off-axis object in all 360 ° directions centered on the optical axis OO ′ outside O ′ is formed in an annular shape on the image plane 5. FIG. 1 is a cross-sectional view of a specific azimuth, in which the luminous flux at the innermost field angle is 11 _i and the luminous flux at the outermost field angle is 11 _o .

したがって、物体側反射面１の開口２を経て反射面１、３間に入射した光軸外の物体からの光束１１_i、１１_oは、像面側反射面３、物体側反射面１の順に反射して、像面側反射面３の開口４を経て反射面１、３間から出て像面５に円環状の像を結像する。その際、物体側反射面１の開口２を経て入射する光束と物体側反射面１で反射されて像面側反射面３の開口４を経て出る光束とは、光軸Ｏ−Ｏ’の光学系１０に入射する方位と反対側で交差するような光路をとって光学系１０から射出する。このように、光軸外の物体からの光束１１_i、１１_oが光軸Ｏ−Ｏ’の片側のみで交差するように構成することで、反射面１、３の開口２、４の外の領域を有効に使うことができ、光学系１０が小型になり、諸収差の発生が少なくなる。 Therefore, the light beams 11 _i and 11 _o from the object outside the optical axis that are incident between the reflecting surfaces 1 and 3 through the opening 2 of the object-side reflecting surface 1 are in order of the image-side reflecting surface 3 and the object-side reflecting surface 1. Reflecting, an annular image is formed on the image plane 5 through the opening 4 of the image plane side reflection plane 3 and out of the reflection planes 1 and 3. At that time, the light beam incident through the opening 2 of the object side reflecting surface 1 and the light beam reflected by the object side reflecting surface 1 and exiting through the opening 4 of the image surface side reflecting surface 3 are optically related to the optical axis OO ′. The light exits from the optical system 10 along an optical path that intersects the direction opposite to the direction of incidence on the system 10. In this way, by configuring the light beams 11 _i and 11 _o from the object outside the optical axis to intersect only on one side of the optical axis OO ′, the outside of the openings 2 and 4 of the reflecting surfaces 1 and 3 is formed. The region can be used effectively, the optical system 10 is downsized, and the occurrence of various aberrations is reduced.

また、本発明に基づいて、物体の中間像２１を反射面１、３の間に１回結像するように構成している。中間像２１を光学系１０内に結像する構成とすると、物体側反射面１の開口２の像を像面側反射面３の開口４の近傍に結像させることが可能になり、光学系１０内に有効径の大きな光束を有効に入射させ、光学系１０から有効径の大きな光束を有効に取り出すことができ、明るい光学系が可能になる。中間像の結像回数をそれ以上に増やすと、光学系１０が特に回転対称軸（光軸）方向に大型化し好ましくない。 Further, according to the present invention, the intermediate image 21 of the object is formed once between the reflecting surfaces 1 and 3. When the intermediate image 21 is formed in the optical system 10, it is possible to form an image of the opening 2 of the object side reflecting surface 1 in the vicinity of the opening 4 of the image side reflecting surface 3. A light beam having a large effective diameter can be effectively entered into the optical system 10 and a light beam having a large effective diameter can be effectively extracted from the optical system 10, so that a bright optical system is possible. If the number of intermediate images is increased more than that, the optical system 10 becomes undesirably large, particularly in the direction of the rotational symmetry axis (optical axis).

また、反射面１、３の中少なくとも１面を光軸Ｏ−Ｏ’上で不連続な回転対称な曲面から構成する。光軸Ｏ−Ｏ’上で不連続な回転対称な曲面としては、トーリック面や、光軸Ｏ−Ｏ’を含む平面上で任意形状の曲線を光軸Ｏ−Ｏ’の周りで回転させて形成される回転自由曲面等から構成する。このような光軸Ｏ−Ｏ’上で不連続な回転対称な曲面は、回転対称軸（光軸）とその曲面が直交する制約を受けなくなるために、サジタル断面とメリジオナル断面の曲率を任意に設定することが可能となり、軸外の諸収差の発生を少なくすることが可能となる。 Further, at least one of the reflecting surfaces 1 and 3 is formed of a rotationally symmetric curved surface that is discontinuous on the optical axis O-O ′. As a rotationally symmetric curved surface that is discontinuous on the optical axis OO ′, a curved line having an arbitrary shape is rotated around the optical axis OO ′ on a toric surface or a plane including the optical axis OO ′. It is composed of a rotation free-form surface to be formed. Such a rotationally symmetric curved surface that is discontinuous on the optical axis OO ′ is not subject to the constraint that the rotationally symmetric axis (optical axis) and the curved surface are orthogonal to each other. This makes it possible to reduce the occurrence of off-axis aberrations.

また、反射面１、３間を屈折率が１より大きな透明媒質６で満たし、反射面１、３の開口２、４近傍にそれぞれ回転対称な入射面７、回転対称な射出面８を設けるようにすることが望ましい。このような屈折面の入射面７、射出面８を備えるようにすると、諸収差の発生をより少なくすることが可能となると共に、光学系１０をより小型化できる。 Further, the space between the reflective surfaces 1 and 3 is filled with a transparent medium 6 having a refractive index larger than 1, and a rotationally symmetric entrance surface 7 and a rotationally symmetric exit surface 8 are provided in the vicinity of the openings 2 and 4 of the reflective surfaces 1 and 3, respectively. It is desirable to make it. By providing the entrance surface 7 and the exit surface 8 having such a refractive surface, it is possible to reduce the occurrence of various aberrations and to further reduce the size of the optical system 10.

また、入射面７、射出面８の一方がそれぞれ反射面１、３を構成する曲面と同一位置同一形状の曲面から構成することにより、製作性が向上する。さらに好ましくは、それを平面にすることで製作性が飛躍的に向上する。 Further, when one of the entrance surface 7 and the exit surface 8 is formed of a curved surface having the same position and the same shape as the curved surfaces that constitute the reflecting surfaces 1 and 3, respectively, the productivity is improved. More preferably, the productivity is drastically improved by making it flat.

また、像面側反射面３を物体側の開口２に凹面を向けた曲面で構成することが好ましい。このように構成すると、観察画角を広くとっても像面側反射面３で反射後の光束は光軸Ｏ−Ｏ’に略平行な光束となり、光学系の大型化を避けることができる。また、コマ収差の発生を小さくすることが可能となる。 In addition, it is preferable that the image-side reflecting surface 3 is constituted by a curved surface having a concave surface directed to the object-side opening 2. With this configuration, the light beam reflected by the image plane side reflecting surface 3 becomes a light beam substantially parallel to the optical axis O-O 'even if the observation angle of view is wide, and an increase in the size of the optical system can be avoided. In addition, the occurrence of coma aberration can be reduced.

また、光軸Ｏ−Ｏ’上で不連続な回転対称な曲面として、光軸Ｏ−Ｏ’を含む平面上で対称面を持たない任意形状の曲線を光軸Ｏ−Ｏ’の周りで回転させて形成される回転自由曲面とすることにより、特に観察画角の広い周辺光路の画角周辺部分の歪みを補正することが可能となる。 Further, an arbitrary-shaped curve having no symmetry plane on the plane including the optical axis OO ′ is rotated around the optical axis OO ′ as a discontinuous rotationally symmetric curved surface on the optical axis OO ′. By using the rotation free-form surface formed as described above, it becomes possible to correct distortion in the peripheral portion of the field angle of the peripheral optical path having a wide observation field angle.

さらに好ましくは、その曲線が奇数次項を含む任意形状の曲線であると、この奇数次項により周辺光路の画面周辺部分の歪をより補正することが可能となる。 More preferably, if the curve is a curve of an arbitrary shape including odd-order terms, the odd-order terms can further correct distortion in the peripheral portion of the screen of the peripheral optical path.

なお、反射面１、３間を屈折率が１より大きな透明媒質６で満たし、反射面１、３の開口２、４近傍にそれぞれ回転対称な入射面７、回転対称な射出面８を設けるようにすると、光軸Ｏ−Ｏ’近傍の画角では、入射面７の屈折面と射出面８の屈折面からなる屈折光学系（単レンズ）となるので、入射面７と射出面８に適切なパワーを与えることにより、近接拡大が可能となり、周辺観察（反射屈折光学系）と拡大観察（屈折光学系）とが１つの光学素子で可能となる（実施例４）。 The space between the reflective surfaces 1 and 3 is filled with a transparent medium 6 having a refractive index larger than 1, and a rotationally symmetric entrance surface 7 and a rotationally symmetric exit surface 8 are provided in the vicinity of the openings 2 and 4 of the reflective surfaces 1 and 3, respectively. Then, at the angle of view near the optical axis OO ′, a refractive optical system (single lens) composed of the refractive surface of the incident surface 7 and the refractive surface of the exit surface 8 is obtained. By applying a sufficient power, close-up magnification is possible, and peripheral observation (catadioptric optical system) and magnified observation (refractive optical system) can be performed with one optical element (Example 4).

次に、本発明の光学系の実施例１〜４について説明する。 Next, Examples 1 to 4 of the optical system of the present invention will be described.

図１を参照にして実施例１の光学系を説明する。図１において、この実施例の光学系１０は対向配置の２面の反射面１、３を備えており、反射面１、３間が屈折率が１より大きな透明媒質６で満たされており、反射面１、３の開口２、４近傍にそれぞれ屈折面の入射面７と射出面８を備えている。ここで、反射面１と反射面３は共に相互に凹面を向かい合わせた光軸Ｏ−Ｏ’上で不連続なトーリック面からなり、入射面７は物体側に凸の球面、射出面８は像面側に凸の球面からなる。そして、入射瞳を形成する絞り９が入射面７位置に配置され、その絞り９の像１９が物体側反射面１から射出面８に到る光路中に結像され、射出瞳を開口４近傍に位置させている。また、遠方の物体の中間像２１を入射面７から像面側反射面３に到る光路中に形成している。 The optical system of Example 1 will be described with reference to FIG. In FIG. 1, the optical system 10 of this embodiment is provided with two reflecting surfaces 1 and 3 facing each other, and the space between the reflecting surfaces 1 and 3 is filled with a transparent medium 6 having a refractive index greater than 1. An entrance surface 7 and an exit surface 8 that are refractive surfaces are provided in the vicinity of the openings 2 and 4 of the reflecting surfaces 1 and 3, respectively. Here, the reflecting surface 1 and the reflecting surface 3 are both discontinuous toric surfaces on the optical axis OO ′ with the concave surfaces facing each other, the incident surface 7 is a convex spherical surface on the object side, and the exit surface 8 is It consists of a spherical surface that is convex on the image side. A stop 9 that forms an entrance pupil is disposed at the position of the entrance surface 7, and an image 19 of the stop 9 is formed in an optical path from the object-side reflecting surface 1 to the exit surface 8. Is located. Further, an intermediate image 21 of a distant object is formed in the optical path from the incident surface 7 to the image surface side reflecting surface 3.

なお、光学系１０の物体側に平行平板のカバーガラス１５を備え、また、像面（撮像面）５の入射側にカバーガラス１６を備えている。 A parallel flat cover glass 15 is provided on the object side of the optical system 10, and a cover glass 16 is provided on the incident side of the image plane (imaging surface) 5.

この実施例においては、図１に示すように、光軸Ｏ−Ｏ’外の遠方の物体からの光は、カバーガラス１５、絞り９、入射面７、反射面３、反射面１、射出面８、カバーガラス１６の順に通り、像面５に結像される。 In this embodiment, as shown in FIG. 1, light from a distant object outside the optical axis OO ′ is transmitted from the cover glass 15, the diaphragm 9, the entrance surface 7, the reflection surface 3, the reflection surface 1, and the exit surface. 8 and the cover glass 16 are passed through in this order to form an image on the image plane 5.

この実施例の構成パラメータは後記するが、図１に示すように、遠方の物体からカバーガラス１５、絞り９、入射面７、反射面３、反射面１、射出面８、カバーガラス１６、像面５に至る順光線追跡の結果に基づくものである。 The configuration parameters of this embodiment will be described later. As shown in FIG. 1, from a distant object, the cover glass 15, the diaphragm 9, the entrance surface 7, the reflection surface 3, the reflection surface 1, the exit surface 8, the cover glass 16, and the image This is based on the result of tracing the forward ray to the surface 5.

座標系は、順光線追跡において、絞り９の中心光線を原点として、光軸Ｏ−Ｏ’の像面５方向をＺ軸正方向とし、図１の紙面内をＹ−Ｚ平面とする。そして、図１の面の紙面の表から裏に向かう方向をＸ軸正方向とし、Ｘ軸、Ｚ軸と右手直交座標系を構成する軸をＹ軸正方向とする。 In the forward ray tracing, the coordinate system uses the central ray of the stop 9 as the origin, the image plane 5 direction of the optical axis O-O ′ is the positive Z-axis direction, and the inside of the paper surface of FIG. 1 is the YZ plane. A direction from the front side to the back side of the plane of FIG. 1 is defined as an X-axis positive direction, and an axis constituting the X-axis, Z-axis and right-handed orthogonal coordinate system is defined as a Y-axis positive direction.

偏心面については、その面が定義される座標系の上記光学系の原点の中心からの偏心量（Ｘ軸方向、Ｙ軸方向、Ｚ軸方向をそれぞれＸ，Ｙ，Ｚ）と、光学系の原点に定義される座標系のＸ軸、Ｙ軸、Ｚ軸それぞれを中心とする各面を定義する座標系の傾き角（それぞれα，β，γ（°））とが与えられている。その場合、αとβの正はそれぞれの軸の正方向に対して反時計回りを、γの正はＺ軸の正方向に対して時計回りを意味する。なお、面の中心軸のα，β，γの回転のさせ方は、各面を定義する座標系を光学系の原点に定義される座標系のまずＸ軸の回りで反時計回りにα回転させ、次に、その回転した新たな座標系のＹ軸の回りで反時計回りにβ回転させ、次いで、その回転した別の新たな座標系のＺ軸の回りで時計回りにγ回転させるものである。 For the decentered surface, the amount of decentering from the center of the origin of the optical system in the coordinate system in which the surface is defined (X-axis direction, Y-axis direction, and Z-axis direction are X, Y, and Z, respectively) and the optical system The inclination angles (α, β, γ (°), respectively) of the coordinate system defining each surface centered on the X axis, Y axis, and Z axis of the coordinate system defined at the origin are given. In this case, positive α and β mean counterclockwise rotation with respect to the positive direction of each axis, and positive γ means clockwise rotation with respect to the positive direction of the Z axis. Note that the α, β, and γ rotations of the central axis of the surface are performed by rotating the coordinate system defining each surface counterclockwise around the X axis of the coordinate system defined at the origin of the optical system. Then rotate it around the Y axis of the new rotated coordinate system by β and then rotate it around the Z axis of another rotated new coordinate system by γ. It is.

また、光学系を構成する光学作用面の中、特定の面とそれに続く面が共軸光学系を構成する場合には面間隔が与えられており、その他、面の曲率半径、媒質の屈折率、アッベ数が慣用法に従って与えられている。 In addition, when a specific surface and subsequent surfaces of the optical working surface constituting the optical system constitute a coaxial optical system, a surface interval is given. In addition, the curvature radius of the surface and the refractive index of the medium are given. , Abbe numbers are given according to idioms.

なお、後記の構成パラメータ中にデータの記載されていない非球面に関する項は０である。屈折率、アッベ数については、ｄ線（波長５８７．５６ｎｍ）に対するものを表記してある。長さの単位はｍｍである。各面の偏心は、上記のように、絞り面中心からの偏心量で表わす。 It should be noted that a term relating to an aspheric surface for which no data is described in the constituent parameters described later is zero. The refractive index and the Abbe number are shown for the d-line (wavelength 587.56 nm). The unit of length is mm. The eccentricity of each surface is expressed by the amount of eccentricity from the center of the diaphragm surface as described above.

なお、トーリック面を含む拡張回転自由曲面（回転自由曲面）は、以下の定義で与えられる回転対称面である。 The extended rotation free-form surface (rotation free-form surface) including the toric surface is a rotationally symmetric surface given by the following definition.

まず、Ｙ−Ｚ座標面上で原点を通る下記の曲線（ｂ）が定められる。 First, the following curve (b) passing through the origin on the YZ coordinate plane is determined.

Ｚ＝（Ｙ²／ＲＹ）／［１＋｛１−（Ｃ₁＋１）Ｙ²／ＲＹ²｝^{1 /2}］
Ｃ₂Ｙ＋Ｃ₃Ｙ²＋Ｃ₄Ｙ³＋Ｃ₅Ｙ⁴＋Ｃ₆Ｙ⁵＋Ｃ₇Ｙ⁶
＋・・・・＋Ｃ₂₁Ｙ²⁰＋・・・・＋Ｃ_n+1Ｙⁿ＋・・・・
・・・（ｂ）
次いで、この曲線（ｂ）をＸ軸正方向を向いて左回りを正として角度θ（°）回転した曲線Ｆ（Ｙ）が定められる。この曲線Ｆ（Ｙ）もＹ−Ｚ座標面上で原点を通る。 ^{Z = (Y 2 / RY)} / [1+ {1- (C 1 +1) Y 2 / RY 2} 1/2]
C ₂ Y + C ₃ Y ² + C ₄ Y ³ + C ₅ Y ⁴ + C ₆ Y ⁵ + C ₇ Y ⁶
+ ··· + C ₂₁ Y ²⁰ + ··· + C _{n + 1} Y ⁿ + ····
... (b)
Next, a curve F (Y) obtained by rotating the curve (b) in the positive direction of the X-axis and turning it counterclockwise to be positive is determined. This curve F (Y) also passes through the origin on the YZ coordinate plane.

その曲線Ｆ（Ｙ）をＹ正方向に距離Ｒ（負のときはＺ負方向）だけ平行移動し、その後にＺ軸の周りでその平行移動した曲線を回転させてできる回転対称面を拡張回転自由曲面とする。 The curve F (Y) is translated in the Y positive direction by a distance R (Z negative direction when negative), and then the rotationally symmetric surface formed by rotating the translated curve around the Z axis is expanded and rotated. Let it be a free-form surface.

その結果、拡張回転自由曲面はＹ−Ｚ面内で自由曲面（自由曲線）になり、Ｘ−Ｙ面内で半径｜Ｒ｜の円になる。 As a result, the extended rotation free-form surface becomes a free-form surface (free-form curve) in the YZ plane and a circle with a radius | R | in the XY plane.

この定義からＺ軸が拡張回転自由曲面の軸（回転対称軸）となる。 From this definition, the Z-axis becomes the axis of the extended rotation free-form surface (rotation symmetry axis).

ここで、ＲＹはＹ−Ｚ断面での球面項の曲率半径、Ｃ₁は円錐定数、Ｃ₂、Ｃ₃、Ｃ₄、Ｃ₅…はそれぞれ１次、２次、３次、４次…の非球面係数である。なお、非球面係数Ｃ₂、Ｃ₃、Ｃ₄、Ｃ₅…が０の場合、トーリック面となり、その特別な場合が球面となる。 Where RY is the radius of curvature of the spherical term in the YZ section, C ₁ is the conic constant, C ₂ , C ₃ , C ₄ , C ₅ . Aspheric coefficient. When the aspheric coefficients C ₂ , C ₃ , C ₄ , C ₅ ... Are 0, a toric surface is obtained, and a special case is a spherical surface.

以下の実施例についても同様である。 The same applies to the following embodiments.

実施例１の仕様は、
画角 10.00°〜60.0°
入射瞳径 φ0.10mm
像の大きさ φ0.46mm〜φ1.83mm
である。 The specification of Example 1 is
Angle of view 10.00 °-60.0 °
Entrance pupil diameter φ0.10mm
Image size φ0.46mm to φ1.83mm
It is.

図２に、この実施例の光学系の横収差を示す。この横収差図において、中央に示された角度は光軸Ｏ−Ｏ’からの画角であり、Ｙ方向（メリジオナル方向）とＸ方向（サジタル方向）の横収差を示す。以下、同じ。 FIG. 2 shows the lateral aberration of the optical system of this example. In this lateral aberration diagram, the angle shown in the center is the angle of view from the optical axis O-O ', and shows lateral aberrations in the Y direction (meridional direction) and the X direction (sagittal direction). same as below.

図３を参照にして実施例２の光学系を説明する。図３において、この実施例の光学系１０は対向配置の２面の反射面１、３を備えており、反射面１、３間が屈折率が１より大きな透明媒質６で満たされており、反射面１、３の開口２、４近傍にそれぞれ屈折面の入射面７と射出面８を備えている。ここで、反射面１と反射面３は共に相互に凹面を向かい合わせた光軸Ｏ−Ｏ’上で不連続な曲面からなり、反射面１はトーリック面、反射面３は拡張回転自由曲面（回転自由曲面）からなり、入射面７は物体側に凸の球面、射出面８は像面側に凸の球面からなる。そして、入射瞳を形成する絞り９が入射面７位置に配置され、その絞り９の像１９が物体側反射面１から射出面８に到る光路中に結像され、射出瞳を開口４近傍に位置させている。また、遠方の物体の中間像２１を入射面７から像面側反射面３に到る光路中に形成している。 The optical system of Example 2 will be described with reference to FIG. In FIG. 3, the optical system 10 of this embodiment is provided with two reflecting surfaces 1 and 3 facing each other, and the space between the reflecting surfaces 1 and 3 is filled with a transparent medium 6 having a refractive index greater than 1. An entrance surface 7 and an exit surface 8 that are refractive surfaces are provided in the vicinity of the openings 2 and 4 of the reflecting surfaces 1 and 3, respectively. Here, the reflecting surface 1 and the reflecting surface 3 are both discontinuous curved surfaces on the optical axis OO ′ with the concave surfaces facing each other, the reflecting surface 1 is a toric surface, and the reflecting surface 3 is an extended rotation free-form surface ( The entrance surface 7 is a convex spherical surface on the object side, and the exit surface 8 is a convex spherical surface on the image surface side. A stop 9 that forms an entrance pupil is disposed at the position of the entrance surface 7, and an image 19 of the stop 9 is formed in an optical path from the object-side reflecting surface 1 to the exit surface 8. Is located. Further, an intermediate image 21 of a distant object is formed in the optical path from the incident surface 7 to the image surface side reflecting surface 3.

この実施例においては、図３に示すように、光軸Ｏ−Ｏ’外の遠方の物体からの光は、カバーガラス１５、絞り９、入射面７、反射面３、反射面１、射出面８、カバーガラス１６の順に通り、像面５に結像される。 In this embodiment, as shown in FIG. 3, light from a distant object outside the optical axis OO ′ is transmitted from the cover glass 15, the diaphragm 9, the incident surface 7, the reflecting surface 3, the reflecting surface 1, and the exit surface. 8 and the cover glass 16 are passed through in this order to form an image on the image plane 5.

この実施例の実施例１と同様の構成パラメータを後記する。 Configuration parameters similar to those of the first embodiment will be described later.

実施例２の仕様は、
画角 10.00°〜60.0°
入射瞳径 φ0.10mm
像の大きさ φ0.45mm〜φ1.82mm
である。 The specification of Example 2 is
Angle of view 10.00 °-60.0 °
Entrance pupil diameter φ0.10mm
Image size φ0.45mm to φ1.82mm
It is.

図４に、この実施例の光学系の図２と同様の横収差を示す。 FIG. 4 shows transverse aberration similar to that of FIG. 2 of the optical system of this example.

図５を参照にして実施例３の光学系を説明する。図５において、この実施例の光学系１０は対向配置の２面の反射面１、３を備えており、反射面１、３間が屈折率が１より大きな透明媒質６で満たされており、反射面１、３の開口２、４近傍にそれぞれ屈折面の入射面７と射出面８を備えている。ここで、反射面１は平面、反射面３は反射面１に対して凹面を向かい合わせ、光軸Ｏ−Ｏ’上で不連続な拡張回転自由曲面（回転自由曲面）からなり、入射面７は反射面１の平面と同じ平面、射出面８は像面側に凸の球面からなる。そして、入射瞳を形成する絞り９が入射面７位置に配置され、その絞り９の像１９が物体側反射面１から射出面８に到る光路中に結像され、射出瞳を開口４近傍に位置させている。また、遠方の物体の中間像２１を像面側反射面３から物体側反射面１に到る光路中に形成している。 The optical system of Example 3 will be described with reference to FIG. In FIG. 5, the optical system 10 of this embodiment includes two reflecting surfaces 1 and 3 facing each other, and the space between the reflecting surfaces 1 and 3 is filled with a transparent medium 6 having a refractive index greater than 1. An entrance surface 7 and an exit surface 8 that are refractive surfaces are provided in the vicinity of the openings 2 and 4 of the reflecting surfaces 1 and 3, respectively. Here, the reflecting surface 1 is a flat surface, the reflecting surface 3 is a concave surface with respect to the reflecting surface 1, and is composed of a discontinuous extended rotation free-form surface (rotation free-form surface) on the optical axis OO ′. Is the same plane as the plane of the reflecting surface 1, and the exit surface 8 is a spherical surface convex toward the image plane side. A stop 9 that forms an entrance pupil is disposed at the position of the entrance surface 7, and an image 19 of the stop 9 is formed in an optical path from the object-side reflecting surface 1 to the exit surface 8. Is located. Further, an intermediate image 21 of a distant object is formed in the optical path from the image surface side reflecting surface 3 to the object side reflecting surface 1.

この実施例においては、図５に示すように、光軸Ｏ−Ｏ’外の遠方の物体からの光は、カバーガラス１５、絞り９、入射面７、反射面３、反射面１、射出面８、カバーガラス１６の順に通り、像面５に結像される。 In this embodiment, as shown in FIG. 5, light from a distant object outside the optical axis OO ′ is transmitted from the cover glass 15, the diaphragm 9, the incident surface 7, the reflecting surface 3, the reflecting surface 1, and the exit surface. 8 and the cover glass 16 are passed through in this order to form an image on the image plane 5.

実施例３の仕様は、
画角 10.00°〜60.0°
入射瞳径 φ0.10mm
像の大きさ φ0.37mm〜φ1.87mm
である。 The specification of Example 3 is
Angle of view 10.00 °-60.0 °
Entrance pupil diameter φ0.10mm
Image size φ0.37mm to φ1.87mm
It is.

図６に、この実施例の光学系の図２と同様の横収差を示す。 FIG. 6 shows lateral aberrations similar to those in FIG. 2 of the optical system of this example.

図７を参照にして実施例４の光学系を説明する。図７において、この実施例の光学系１０は対向配置の２面の反射面１、３を備えており、反射面１、３間が屈折率が１より大きな透明媒質６で満たされており、反射面１、３の開口２、４近傍にそれぞれ屈折面の入射面７と射出面８を備えている。ここで、反射面１は平面、反射面３は反射面１に対して凹面を向かい合わせ、光軸Ｏ−Ｏ’上で不連続な拡張回転自由曲面（回転自由曲面）からなり、入射面７は反射面１の平面と同じ平面、射出面８は像面側に凸の球面からなる。そして、入射瞳を形成する絞り９が入射面７位置に配置され、その絞り９の像１９が物体側反射面１から射出面８に到る光路中に結像され、射出瞳を開口４近傍に位置させている。また、遠方の物体の中間像２１を像面側反射面３から物体側反射面１に到る光路中に形成している。 The optical system of Example 4 will be described with reference to FIG. In FIG. 7, the optical system 10 of this embodiment is provided with two reflecting surfaces 1 and 3 facing each other, and the space between the reflecting surfaces 1 and 3 is filled with a transparent medium 6 having a refractive index greater than 1. An entrance surface 7 and an exit surface 8 that are refractive surfaces are provided in the vicinity of the openings 2 and 4 of the reflecting surfaces 1 and 3, respectively. Here, the reflecting surface 1 is a flat surface, the reflecting surface 3 is a concave surface with respect to the reflecting surface 1, and is composed of a discontinuous extended rotation free-form surface (rotation free-form surface) on the optical axis OO ′. Is the same plane as the plane of the reflecting surface 1, and the exit surface 8 is a spherical surface convex toward the image plane side. A stop 9 that forms an entrance pupil is disposed at the position of the entrance surface 7, and an image 19 of the stop 9 is formed in an optical path from the object-side reflecting surface 1 to the exit surface 8. Is located. Further, an intermediate image 21 of a distant object is formed in the optical path from the image surface side reflecting surface 3 to the object side reflecting surface 1.

この実施例においては、図７に示すように、光軸Ｏ−Ｏ’外の遠方の物体からの光は、カバーガラス１５、絞り９、入射面７、反射面３、反射面１、射出面８、カバーガラス１６の順に通り、像面５に結像される。 In this embodiment, as shown in FIG. 7, light from a distant object outside the optical axis OO ′ is transmitted from the cover glass 15, the diaphragm 9, the incident surface 7, the reflecting surface 3, the reflecting surface 1, and the exit surface. 8 and the cover glass 16 are passed through in this order to form an image on the image plane 5.

そして、この実施例においては、上記のように、光軸Ｏ−Ｏ’の外の遠方の物体からの像を像面５に円環状に結像する（周辺光路）以外に、光軸Ｏ−Ｏ’近傍に位置する近距離物体面２０の像を、カバーガラス１５、入射面７、射出面８、カバーガラス１６の順に通り、像面５の中心近傍に結像する（中心光路）。すなわち、近距離物体面２０に対しては、入射面７と射出面８で挟まれた透明媒質６が単レンズの作用をして近距離物体面２０の像を像面に結像する。 In this embodiment, as described above, an image from a distant object outside the optical axis OO ′ is formed on the image plane 5 in an annular shape (peripheral optical path), and the optical axis O− An image of the short-distance object surface 20 located in the vicinity of O ′ passes through the cover glass 15, the incident surface 7, the exit surface 8, and the cover glass 16 in this order, and forms an image near the center of the image surface 5 (center optical path). That is, with respect to the short-distance object plane 20, the transparent medium 6 sandwiched between the entrance plane 7 and the exit plane 8 acts as a single lens to form an image of the short-range object plane 20 on the image plane.

この実施例の周辺光路と中心光路の構成パラメータは後記する。 The configuration parameters of the peripheral optical path and the central optical path in this embodiment will be described later.

実施例４の仕様は、
画角（周辺光路） 10.00°〜60.0°
（中心光路） 5.00°
入射瞳径（周辺光路） φ0.20mm
（中心光路） φ0.40mm
像の大きさ（周辺光路） φ0.37mm〜φ1.91mm
（中心光路） φ0.35mm
である。 The specification of Example 4 is
Angle of view (peripheral light path) 10.00 ° ~ 60.0 °
(Central optical path) 5.00 °
Entrance pupil diameter (peripheral optical path) φ0.20mm
(Center optical path) φ0.40mm
Image size (peripheral optical path) φ0.37mm to φ1.91mm
(Center optical path) φ0.35mm
It is.

図８、図９に、この実施例の光学系のそれぞれ周辺光路と中心光路の図２と同様の横収差を示す。 8 and 9 show lateral aberrations similar to those in FIG. 2 for the peripheral optical path and the central optical path, respectively, of the optical system of this example.

以下に、上記実施例１〜４の構成パラメータを示す。なお、以下の表中の“ＥＲＦＳ”は拡張回転自由曲面、“ＲＳ”は反射面を示す。 The configuration parameters of Examples 1 to 4 are shown below. In the table below, “ERFS” indicates an extended rotation free-form surface, and “RS” indicates a reflective surface.

実施例１
面番号曲率半径面間隔偏心屈折率アッベ数
物体面 ∞ 10.00
1 ∞ 0.50 1.5163 64.1
2 ∞ 0.20
3 ∞（絞り） 0.00
4 1.29 1.8348 42.7
5 ＥＲＦＳ[1] （ＲＥ）偏心(1) 1.8348 42.7
6 ＥＲＦＳ[2] （ＲＥ）偏心(2) 1.8348 42.7
7 -1.20 1.00 偏心(3)
8 ∞ 0.40 1.5163 64.1
9 ∞ 0.10
像面 ∞
ＥＲＦＳ[1]
ＲＹ -4.07
θ 9.71
Ｒ 0.91
ＥＲＦＳ[2]
ＲＹ -84.83
θ -3.63
Ｒ 0.71
偏心(1)
Ｘ 0.00 Ｙ 0.00 Ｚ 3.24
α 0.00 β 0.00 γ 0.00
偏心(2)
Ｘ 0.00 Ｙ 0.00 Ｚ 0.02
α 0.00 β 0.00 γ 0.00
偏心(3)
Ｘ 0.00 Ｙ 0.00 Ｚ 3.30
α 0.00 β 0.00 γ 0.00 。
Example 1
Surface number Curvature radius Surface spacing Eccentric Refractive index Abbe number Object surface ∞ 10.00
1 ∞ 0.50 1.5163 64.1
2 ∞ 0.20
3 ∞ (Aperture) 0.00
4 1.29 1.8348 42.7
5 ERFS [1] (RE) Eccentricity (1) 1.8348 42.7
6 ERFS [2] (RE) Eccentricity (2) 1.8348 42.7
7 -1.20 1.00 Eccentricity (3)
8 ∞ 0.40 1.5163 64.1
9 ∞ 0.10
Image plane ∞
ERFS [1]
RY -4.07
θ 9.71
R 0.91
ERFS [2]
RY -84.83
θ -3.63
R 0.71
Eccentricity (1)
X 0.00 Y 0.00 Z 3.24
α 0.00 β 0.00 γ 0.00
Eccentricity (2)
X 0.00 Y 0.00 Z 0.02
α 0.00 β 0.00 γ 0.00
Eccentricity (3)
X 0.00 Y 0.00 Z 3.30
α 0.00 β 0.00 γ 0.00.

実施例２
面番号曲率半径面間隔偏心屈折率アッベ数
物体面 ∞ 10.00
1 ∞ 0.50 1.5163 64.1
2 ∞ 0.20
3 ∞（絞り） 0.00
4 1.31 1.8348 42.7
5 ＥＲＦＳ[1] （ＲＥ）偏心(1) 1.8348 42.7
6 ＥＲＦＳ[2] （ＲＥ）偏心(2) 1.8348 42.7
7 -1.19 1.02 偏心(3)
8 ∞ 0.40 1.5163 64.1
9 ∞ 0.10
像面 ∞
ＥＲＦＳ[1]
ＲＹ -3.98
θ 9.82
Ｒ 0.91
Ｃ₄ -4.9130 ×10^-4
Ｃ₅ 3.7986 ×10^-3
ＥＲＦＳ[2]
ＲＹ -120.49
θ -3.41
Ｒ 0.70
偏心(1)
Ｘ 0.00 Ｙ 0.00 Ｚ 3.23
α 0.00 β 0.00 γ 0.00
偏心(2)
Ｘ 0.00 Ｙ 0.00 Ｚ 0.02
α 0.00 β 0.00 γ 0.00
偏心(3)
Ｘ 0.00 Ｙ 0.00 Ｚ 3.30
α 0.00 β 0.00 γ 0.00 。
Example 2
Surface number Curvature radius Surface spacing Eccentric Refractive index Abbe number Object surface ∞ 10.00
1 ∞ 0.50 1.5163 64.1
2 ∞ 0.20
3 ∞ (Aperture) 0.00
4 1.31 1.8348 42.7
5 ERFS [1] (RE) Eccentricity (1) 1.8348 42.7
6 ERFS [2] (RE) Eccentricity (2) 1.8348 42.7
7 -1.19 1.02 Eccentricity (3)
8 ∞ 0.40 1.5163 64.1
9 ∞ 0.10
Image plane ∞
ERFS [1]
RY -3.98
θ 9.82
R 0.91
C ₄ -4.9130 × 10 ^-4
C ₅ 3.7986 × 10 ^-3
ERFS [2]
RY -120.49
θ -3.41
R 0.70
Eccentricity (1)
X 0.00 Y 0.00 Z 3.23
α 0.00 β 0.00 γ 0.00
Eccentric (2)
X 0.00 Y 0.00 Z 0.02
α 0.00 β 0.00 γ 0.00
Eccentricity (3)
X 0.00 Y 0.00 Z 3.30
α 0.00 β 0.00 γ 0.00.

実施例３
面番号曲率半径面間隔偏心屈折率アッベ数
物体面 ∞ 10.00
1 ∞ 5.00 1.5163 64.1
2 ∞ 0.10
3 ∞（絞り） 0.00 4 ∞ 1.8348 42.7
5 ＥＲＦＳ[1] （ＲＥ）偏心(1) 1.8348 42.7
6 ∞ （ＲＥ） 1.8348 42.7
7 -0.93 1.64 偏心(2)
8 ∞ 0.40 1.5163 64.1
9 ∞ 0.10
像面 ∞
ＥＲＦＳ[1]
ＲＹ -3.98
θ 12.14
Ｒ 0.88
Ｃ₄ 3.0732 ×10^-3
Ｃ₅ 6.3495 ×10^-3
偏心(1)
Ｘ 0.00 Ｙ 0.00 Ｚ 3.11
α 0.00 β 0.00 γ 0.00
偏心(2)
Ｘ 0.00 Ｙ 0.00 Ｚ 3.19
α 0.00 β 0.00 γ 0.00 。
Example 3
Surface number Curvature radius Surface spacing Eccentric Refractive index Abbe number Object surface ∞ 10.00
1 ∞ 5.00 1.5163 64.1
2 ∞ 0.10
3 ∞ (Aperture) 0.00 4 ∞ 1.8348 42.7
5 ERFS [1] (RE) Eccentricity (1) 1.8348 42.7
6 ∞ (RE) 1.8348 42.7
7 -0.93 1.64 Eccentricity (2)
8 ∞ 0.40 1.5163 64.1
9 ∞ 0.10
Image plane ∞
ERFS [1]
RY -3.98
θ 12.14
R 0.88
C ₄ 3.0732 × 10 ^-3
C ₅ 6.3495 × 10 ^-3
Eccentricity (1)
X 0.00 Y 0.00 Z 3.11
α 0.00 β 0.00 γ 0.00
Eccentricity (2)
X 0.00 Y 0.00 Z 3.19
α 0.00 β 0.00 γ 0.00.

実施例４
（周辺光路）
面番号曲率半径面間隔偏心屈折率アッベ数
物体面 ∞ 10.00
1 ∞ 0.50 1.5163 64.1
2 ∞ 0.10
3 ∞（絞り） 0.00 4 ∞ 1.8348 42.7
5 ＥＲＦＳ[1] （ＲＥ）偏心(1) 1.8348 42.7
6 ∞ （ＲＥ） 1.8348 42.7
7 -0.93 1.64 偏心(2)
8 ∞ 0.40 1.5163 64.1
9 ∞ 0.10
像面 ∞
ＥＲＦＳ[1]
ＲＹ -3.98
θ 12.14
Ｒ 0.88
Ｃ₄ 3.0732 ×10^-3
Ｃ₅ 6.3495 ×10^-3
偏心(1)
Ｘ 0.00 Ｙ 0.00 Ｚ 3.11
α 0.00 β 0.00 γ 0.00
偏心(2)
Ｘ 0.00 Ｙ 0.00 Ｚ 3.19
α 0.00 β 0.00 γ 0.00
（中心光路）
面番号曲率半径面間隔偏心屈折率アッベ数
物体面 ∞ 0.10
1 ∞ 0.50 1.5163 64.1
2 ∞ 0.10
3 ∞（絞り） 0.00
4 ∞ 3.19 1.8348 42.7
5 -0.93 1.64
6 ∞ 0.40 1.5163 64.1
7 ∞ 0.10
像面 ∞ 。
Example 4
(Ambient light path)
Surface number Curvature radius Surface spacing Eccentric Refractive index Abbe number Object surface ∞ 10.00
1 ∞ 0.50 1.5163 64.1
2 ∞ 0.10
3 ∞ (Aperture) 0.00 4 ∞ 1.8348 42.7
5 ERFS [1] (RE) Eccentricity (1) 1.8348 42.7
6 ∞ (RE) 1.8348 42.7
7 -0.93 1.64 Eccentricity (2)
8 ∞ 0.40 1.5163 64.1
9 ∞ 0.10
Image plane ∞
ERFS [1]
RY -3.98
θ 12.14
R 0.88
C ₄ 3.0732 × 10 ^-3
C ₅ 6.3495 × 10 ^-3
Eccentricity (1)
X 0.00 Y 0.00 Z 3.11
α 0.00 β 0.00 γ 0.00
Eccentricity (2)
X 0.00 Y 0.00 Z 3.19
α 0.00 β 0.00 γ 0.00
(Central optical path)
Surface number Curvature radius Surface spacing Eccentric Refractive index Abbe number Object surface ∞ 0.10
1 ∞ 0.50 1.5163 64.1
2 ∞ 0.10
3 ∞ (Aperture) 0.00
4 ∞ 3.19 1.8348 42.7
5 -0.93 1.64
6 ∞ 0.40 1.5163 64.1
7 ∞ 0.10
Image plane ∞.

本発明において、さらに好ましくは、最大像高をＩｍｍ、入射面７から射出面８までの距離ｄｍｍとするとき、
２＜ｄ／Ｉ＜５・・・（１）
なる条件を満足することが望ましい。 In the present invention, more preferably, when the maximum image height is Imm and the distance dmm from the entrance surface 7 to the exit surface 8 is:
2 <d / I <5 (1)
It is desirable to satisfy the following conditions.

上記条件式（１）は、下限の２を越えると、光学系１０内で１回中間像２１を結像するために必要な光路長を短くするために、各反射面１、３のパワーが強くなりすぎ、収差が大きく発生する。上限の５を越えると、光学系１０が大きくなりすぎてしまい、小型の光学系を実現できない。 When the above conditional expression (1) exceeds the lower limit of 2, the power of the reflecting surfaces 1 and 3 is reduced in order to shorten the optical path length necessary for forming the intermediate image 21 once in the optical system 10. It becomes too strong and large aberrations occur. If the upper limit of 5 is exceeded, the optical system 10 becomes too large, and a compact optical system cannot be realized.

上記実施例１〜４のＩ、ｄ、ｄ／Ｉの値は次の通りである。 The values of I, d, and d / I in Examples 1 to 4 are as follows.

実施例１実施例２実施例３実施例４
Ｉ 0.91 0.91 0.95 0.95
ｄ 3.30 3.29 3.19 3.19
ｄ／Ｉ 3.63 3.62 3.36 3.36 。 Example 1 Example 2 Example 3 Example 4
I 0.91 0.91 0.95 0.95
d 3.30 3.29 3.19 3.19
d / I 3.63 3.62 3.36 3.36.

以上のような本発明の光学系は、例えば管内観察装置、カプセル内視鏡、車載カメラ等の対物光学系あるいは投影光学系として使用可能である。 The optical system of the present invention as described above can be used as an objective optical system or a projection optical system such as an in-tube observation apparatus, a capsule endoscope, and an in-vehicle camera.

本発明の実施例１の光学系の光軸を含み光路を示す断面図である。It is sectional drawing which shows the optical path including the optical axis of the optical system of Example 1 of this invention. 実施例１の光学系の横収差図である。2 is a lateral aberration diagram of the optical system of Example 1. FIG. 本発明の実施例２の光学系の光軸を含み光路を示す断面図である。It is sectional drawing which shows the optical path including the optical axis of the optical system of Example 2 of this invention. 実施例２の光学系の横収差図である。6 is a lateral aberration diagram of the optical system of Example 2. FIG. 本発明の実施例３の光学系の光軸を含み光路を示す断面図である。It is sectional drawing which shows the optical path including the optical axis of the optical system of Example 3 of this invention. 実施例３の光学系の横収差図である。5 is a lateral aberration diagram of the optical system of Example 3. FIG. 本発明の実施例４の光学系の光軸を含み光路を示す断面図である。It is sectional drawing which shows the optical path including the optical axis of the optical system of Example 4 of this invention. 実施例４の光学系の周辺光路の横収差図である。6 is a lateral aberration diagram of a peripheral optical path of the optical system according to Example 4. FIG. 実施例４の光学系の中心光路の横収差図である。6 is a lateral aberration diagram of the central optical path of the optical system of Example 4. FIG.

Explanation of symbols

Ｏ−Ｏ’…光軸（回転対称軸）
１…物体側反射面
２…物体側反射面の開口
３…像面側反射面
４…像面側反射面の開口
５…像面
６…透明媒質
７…入射面
８…射出面
９…絞り
１０…光学系（本発明）
１１_i…最内画角の光束
１１_o…最外画角の光束
１５、１６…カバーガラス
１９…絞りの像
２０…近距離物体面
２１…光軸外物体の中間像 OO '... Optical axis (Axis of rotation symmetry)
DESCRIPTION OF SYMBOLS 1 ... Object side reflective surface 2 ... Object side reflective surface opening 3 ... Image surface side reflective surface 4 ... Image surface side reflective surface opening 5 ... Image surface 6 ... Transparent medium 7 ... Incident surface 8 ... Ejection surface 9 ... Diaphragm 10 ... Optical system (present invention)
11 _i ... Light flux of innermost field angle 11 _o ... Light fluxes 15 and 16 of outermost field angle ... Cover glass 19 ... Image of aperture 20 ... Short-distance object plane 21 ... Intermediate image of off-axis object

Claims

An optical system that is rotationally symmetric with respect to the optical axis, and includes two opposing reflecting surfaces, each of the reflecting surfaces having an opening in the center including the optical axis, and passing through the opening of the object side reflecting surface. A light beam from an object outside the optical axis that is incident between the reflecting surfaces of the surfaces is reflected in the order of the image-side reflecting surface and the object-side reflecting surface, and passes through the opening of the image-side reflecting surface so that two reflecting surfaces are obtained. An optical system for forming an image on the image plane through the space, a light beam incident through the opening of the object side reflecting surface and a light beam reflected by the object side reflecting surface and exiting through the opening of the image side reflecting surface In an optical system where and intersect only on one side of the optical axis,
An intermediate image of an object is formed only once between the two reflecting surfaces, and at least one of the reflecting surfaces is formed of a rotationally symmetric curved surface that is discontinuous on the optical axis. Optical system.

A space between the two reflecting surfaces is filled with a transparent medium, and a rotationally symmetric incident surface is provided near the opening of the object side reflecting surface, and a rotationally symmetric exit surface is provided near the opening of the image side reflecting surface. The optical system according to claim 1.

3. The optical system according to claim 2, wherein one of the entrance surface and the exit surface is a curved surface having the same position and shape as the curved surface constituting the object-side reflecting surface and the image-side reflecting surface, respectively.

4. The optical system according to claim 1, wherein the rotationally symmetric curved surface discontinuous on the optical axis is a toric surface.

The rotation-symmetric curved surface discontinuous on the optical axis is a free-form curved surface formed by rotating an arbitrarily shaped curve around the optical axis on a plane including the optical axis. 4. The optical system according to any one of 3.

The rotationally symmetric curved surface that is discontinuous on the optical axis is a rotationally free curved surface that is formed by rotating an arbitrary-shaped curve including an odd-order term on a plane including the optical axis around the optical axis. The optical system according to claim 5.

The light beam from an object in the vicinity of the optical axis in front of the opening of the object-side reflecting surface passes through the incident surface and the exit surface in this order and forms an image on the image surface. The optical system according to any one of the above.