JP5031631B2

JP5031631B2 - Optical system and endoscope using the same

Info

Publication number: JP5031631B2
Application number: JP2008071176A
Authority: JP
Inventors: 孝吉研野
Original assignee: Olympus Corp
Current assignee: Olympus Corp
Priority date: 2007-09-27
Filing date: 2008-03-19
Publication date: 2012-09-19
Anticipated expiration: 2028-03-19
Also published as: JP2009098600A

Description

本発明は光学系及びそれを用いた内視鏡に関し、特に、回転対称軸周りの映像を撮像素子に円環状の映像として結像する機能を有する結像光学系又は投影光学系に関するものである。 The present invention relates to an optical system and an endoscope using the same, and more particularly to an imaging optical system or a projection optical system having a function of forming an image around a rotationally symmetric axis as an annular image on an image sensor. .

従来、２面の球面又は放物面鏡を組み合わせた光学系があった。
特許第３３８２６８３号公報特許第３２１２７８４号公報特公昭６２−５２８４２号公報 Conventionally, there has been an optical system combining two spherical surfaces or a parabolic mirror.
Japanese Patent No. 3382683 Japanese Patent No. 3212784 Japanese Patent Publication No.62-52842

しかしながら、どの特許文献に記載された光学系も、小型な構成で、且つ、高画角の映像を得ることはできなかった。 However, none of the optical systems described in any of the patent documents can obtain a high-angle image with a small configuration.

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、簡単な構成で広い観察画角を撮像素子上に撮像することが可能であり、小型で安価な光学系及びそれを用いた内視鏡を提供することである。 The present invention has been made in view of such a situation of the prior art, and an object of the present invention is to allow a wide observation angle of view to be imaged on an image sensor with a simple configuration, and to be a small and inexpensive optical. A system and an endoscope using the system are provided.

上記目的を達成する本発明の光学系は、少なくとも１つの反射面を含む前群と、後群と、前記前群と前記後群の間に配置された開口とを有し、中心軸を含む断面内で、前記中心軸の周りで回転対称な光学系において、前記後群は、前記開口の像面側に配置され、屈折率が１より大きい後群透明媒体を有し、前記後群透明媒体は、前記開口近傍の前記中心軸上に配置された後群第１透過面と、前記後群第１透過面より像面側に配置され、像面側に凹面を向けた後群第１反射面と、前記後群第１反射面より像面と反対側に配置され、像面側に凹面を向けた後群第２反射面と、前記後群第２反射面より像面側に配置された後群第２透過面と、を有し、前記後群第１反射面と前記後群第２反射面のうち少なくとも１面は、中心軸上で連続な曲面で構成されており、前記後群透明媒体に入射する光束は、順光線追跡の順に、前記開口を通り、前記後群第１透過面を経て前記後群透明媒体内に入り、前記後群第１反射面で像面と反対側に反射され、前記後群第２反射面で像面側に反射され、前記後群第２透過面を経て前記後群透明媒体から像面側に外へ出る略Ｚ字状の第１光路を構成し、前記第１光路の少なくとも前記後群第１反射面と前記後群第２反射面の間は、前記中心軸に対して片側のみで構成され、前記第１光路中に中間像が結像されることなく、像面に円環状に結像されることを特徴とする。 An optical system of the present invention that achieves the above object includes a front group including at least one reflecting surface, a rear group, and an aperture disposed between the front group and the rear group, and includes a central axis. In an optical system that is rotationally symmetric about the central axis in a cross section, the rear group is disposed on the image plane side of the aperture and has a rear group transparent medium having a refractive index greater than 1, and the rear group transparent The medium is a rear group first transmission surface disposed on the central axis in the vicinity of the opening, and a rear group first material is disposed closer to the image plane side than the rear group first transmission surface and has a concave surface facing the image plane side. A reflective surface, a rear group second reflective surface disposed on the opposite side of the image surface from the rear group first reflective surface, with a concave surface facing the image surface side, and disposed on the image surface side from the rear group second reflective surface A rear group second transmitting surface, and at least one of the rear group first reflecting surface and the rear group second reflecting surface is formed by a continuous curved surface on a central axis. The light beam incident on the rear group transparent medium passes through the aperture in the order of forward ray tracing, enters the rear group transparent medium through the rear group first transmission surface, and then receives the rear group first reflection. Z is reflected to the opposite side of the image surface by the surface, reflected to the image surface side by the rear group second reflecting surface, and exits from the rear group transparent medium to the image surface side through the rear group second transmitting surface. A first optical path having a letter shape, and at least a portion between the rear group first reflecting surface and the rear group second reflecting surface of the first optical path is configured only on one side with respect to the central axis; An intermediate image is not formed in the optical path, but is formed in an annular shape on the image plane.

また、前記後群の第１反射面は球面であることを特徴とする。 In addition, the first reflecting surface of the rear group is a spherical surface.

また、前記後群第１反射面は、全反射作用と、反射コーティングにより反射するように構成され、前記反射コーティングは前記後群第１反射面の中心軸近傍のみに施されていることを特徴とする。 Further, the rear group first reflecting surface is configured to reflect by a total reflection action and a reflecting coating, and the reflecting coating is provided only in the vicinity of the central axis of the rear group first reflecting surface. And

また、前記後群第１透過面と前記後群第２反射面は、前記後群透明媒体の物体側に配置されていることを特徴とする。 Further, the rear group first transmission surface and the rear group second reflection surface are arranged on the object side of the rear group transparent medium.

また、前記後群第１透過面と前記後群第２反射面は、同一位置同一形状からなることを
特徴とする。 Further, the rear group first transmission surface and the rear group second reflection surface have the same shape at the same position.

また、前記後群第１反射面と前記後群第２透過面は、前記後群透明媒体の像面側に配置されていることを特徴とする。 Further, the rear group first reflecting surface and the rear group second transmitting surface are arranged on the image surface side of the rear group transparent medium.

また、前記後群第１反射面と前記後群第２透過面は、同一位置同一形状からなることを特徴とする。 Further, the rear group first reflecting surface and the rear group second transmitting surface have the same shape at the same position.

また、前記前群は、中心軸の周りで回転対称な屈折率が１より大きい前群透明媒体を有し、前記前群透明媒体は、前群第１透過面と、前記前群第１透過面より像面側に配置された前群第１反射面と、前記前群第１反射面より像面と反対側に配置された前群第２反射面と、前記前群第２反射面より像面側に配置された前群第２透過面と、を有し、前記前群透明媒体に入射する光束は、順光線追跡の順に、前記前群第１透過面を経て前記前群透明媒体内に入り、中心軸と交差した後、前記前群第１反射面で像面と反対側に反射され、中心軸と交差することなく、前記前群第２反射面で像面側に反射され、前記前群第２透過面を経て前記前群透明媒体から像面側に外へ出る光路を構成することを特徴とする。 The front group includes a front group transparent medium having a refractive index rotationally symmetric about a central axis greater than 1, and the front group transparent medium includes a front group first transmission surface and the front group first transmission medium. From the front group first reflecting surface disposed on the image surface side from the surface, from the front group second reflecting surface disposed on the side opposite to the image surface from the front group first reflecting surface, and from the front group second reflecting surface A front group second transmission surface disposed on the image plane side, and a light beam incident on the front group transparent medium passes through the front group first transmission surface in the order of forward ray tracing, and the front group transparent medium After entering and intersecting the central axis, it is reflected on the opposite side of the image surface by the front group first reflecting surface, and is reflected on the image surface side by the front group second reflecting surface without intersecting the central axis. And an optical path that exits from the front group transparent medium to the image plane side through the front group second transmission surface.

また、前記前群は、中心軸の周りで回転対称な屈折率が１より大きい前群透明媒体を有し、前記前群透明媒体は、前群第１透過面と、前記前群第１透過面より像面側に配置された前群第１反射面と、前記前群第１反射面より像面と反対側に配置された前群第２反射面と、前記前群第２反射面より像面側に配置された前群第２透過面と、を有し、前記前群透明媒体に入射する光束は、順光線追跡の順に、前記前群第１透過面を経て前記前群透明媒体内に入り、中心軸と交差した後、前記前群第１反射面で像面と反対側に反射され、再度中心軸と交差した後、前記前群第２反射面で像面側に反射され、前記前群第２透過面を経て前記前群透明媒体から像面側に外へ出る光路を構成することを特徴とする。 The front group includes a front group transparent medium having a refractive index rotationally symmetric about a central axis greater than 1, and the front group transparent medium includes a front group first transmission surface and the front group first transmission medium. From the front group first reflecting surface disposed on the image surface side from the surface, from the front group second reflecting surface disposed on the side opposite to the image surface from the front group first reflecting surface, and from the front group second reflecting surface A front group second transmission surface disposed on the image plane side, and a light beam incident on the front group transparent medium passes through the front group first transmission surface in the order of forward ray tracing, and the front group transparent medium After entering and intersecting the central axis, it is reflected to the opposite side of the image plane by the front group first reflecting surface, and after intersecting the central axis again, it is reflected to the image plane side by the front group second reflecting surface. And an optical path that exits from the front group transparent medium to the image plane side through the front group second transmission surface.

また、前記前群は、中心軸の周りで回転対称な屈折率が１より大きい前群透明媒体を有し、前記前群透明媒体は、前群第１透過面と、前記前群第１透過面より像面と反対側に配置された前群第１反射面と、前記前群第１反射面より像面側に配置された前群第２透過面と、を有し、前記前群透明媒体に入射する光束は、順光線追跡の順に、前記前群第１透過面を経て前記前群透明媒体内に入り、中心軸と交差した後、前記前群第１反射面で像面側に反射され、前記前群第２透過面を経て前記前群透明媒体から像面側に外へ出る光路を構成することを特徴とする。 The front group includes a front group transparent medium having a refractive index rotationally symmetric about a central axis greater than 1, and the front group transparent medium includes a front group first transmission surface and the front group first transmission medium. A front group first reflecting surface disposed on the opposite side of the image surface from the surface, and a front group second transmitting surface disposed on the image surface side from the front group first reflecting surface, and the front group transparent A light beam incident on the medium enters the front group transparent medium through the front group first transmission surface in the order of forward ray tracing, intersects the central axis, and then enters the image plane side on the front group first reflection surface. An optical path which is reflected and goes out from the front group transparent medium to the image surface side through the front group second transmission surface is formed.

また、最大像高をＩmax、前記後群の外径をＤとするとき、
０．５＜Ｄ／（２×Ｉmax）＜１０・・・（１）
なる条件を満足することを特徴とする。 When the maximum image height is Imax and the outer diameter of the rear group is D,
0.5 <D / (2 × Imax) <10 (1)
It satisfies the following condition.

また、最大像高をＩmax、前記開口から前記像面までの距離をＬとするとき、
０．５＜Ｌ／（２×Ｉmax）＜１０・・・（２）
なる条件を満足することを特徴とする。 When the maximum image height is Imax and the distance from the opening to the image plane is L,
0.5 <L / (2 × Imax) <10 (2)
It satisfies the following condition.

また、後群第１反射面の曲率をＲ１、後群第２反射面の曲率をＲ２とするとき、
０．２＜Ｒ１／Ｒ２＜５・・・（３）
なる条件を満足することを特徴とする。 Further, when the curvature of the rear group first reflecting surface is R1, and the curvature of the rear group second reflecting surface is R2,
0.2 <R1 / R2 <5 (3)
It satisfies the following condition.

さらに、上記目的を達成する本発明は、前記光学系を用いた内視鏡であることを特徴とする。 Furthermore, the present invention for achieving the above object is an endoscope using the optical system.

以上の本発明の光学系においては、簡単な構成で広い画角を観察又は広い画角に映像を投影することが可能な小型で収差が良好に補正された解像力の良い光学系を得ることができる。 In the optical system of the present invention described above, it is possible to obtain a small optical system with good resolving power with a well-corrected aberration capable of observing a wide angle of view or projecting an image at a wide angle of view with a simple configuration. it can.

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

図３は、後述する実施例１の光学系１の中心軸（回転対称軸）２に沿ってとった断面図である。なお、以下の説明は、結像光学系として説明するが、光路を逆にとって投影光学系として用いることもできる。 FIG. 3 is a cross-sectional view taken along the central axis (rotation symmetry axis) 2 of the optical system 1 of Example 1 described later. In the following description, the imaging optical system will be described. However, it can be used as a projection optical system with the optical path reversed.

本発明に係る光学系１は、中心軸２に対して回転対称で、少なくとも１つの反射面を含む前群Ｇｆと、開口Ｓと、後群Ｇｂとからなり、中間像を光路中に形成することなく像を形成又は投影する光学系１である。像面５近傍の平行平板は撮像素子のカバーガラスＣ等である。 The optical system 1 according to the present invention is rotationally symmetric with respect to the center axis 2 and includes a front group Gf including at least one reflecting surface, an aperture S, and a rear group Gb, and forms an intermediate image in the optical path. The optical system 1 forms or projects an image without any problem. The parallel flat plate near the image plane 5 is a cover glass C of the image sensor or the like.

実施例１の光学系１は、少なくとも１つの反射面を含む前群Ｇｆと、後群Ｇｂと、前群Ｇｆと後群Ｇｂの間に配置された開口Ｓとを有し、中心軸２を含む断面内で、中心軸２の周りで回転対称な光学系１において、後群Ｇｂは、開口Ｓの像面５側に配置され、屈折率が１より大きい後群透明媒体としての後１群透明媒体Ｌｂを有し、後１群透明媒体Ｌｂは、開口Ｓ近傍の中心軸２上に配置された後群第１透過面としての後１群第１透過面２１と、後１群第１透過面２１より像面側に配置され、像面側に凹面を向けた後群第１反射面としての後１群第１反射面２２と、後１群第１反射面２２より像面と反対側に配置され、像面側に凹面を向けた後群第２反射面としての後１群第２反射面２３と、後１群第２反射面２３より像面側に配置された後群第２透過面としての後１群第２透過面２４と、を有し、後１群第１透過面２１、後１群第１反射面２２、後１群第２反射面２３及び後１群第２透過面２４は、球面からなり、透明媒体Ｌに入射する光束は、順光線追跡の順に、開口Ｓを通り、後１群第１透過面２１を経て透明媒体Ｌ内に入り、後１群第１反射面２２で像面５と反対側に反射され、後１群第２反射面２３で像面５側に反射され、後１群第２透過面２４を経て透明媒体Ｌから像面５側に外へ出る略Ｚ字状の第１光路Ａを構成し、第１光路Ａの少なくとも後１群第１反射面２２と後１群第２反射面２３の間は、中心軸２に対して片側のみで構成され、第１光路Ａ中に中間像が結像されることなく、像面５に円環状に結像される。 The optical system 1 of Example 1 includes a front group Gf including at least one reflecting surface, a rear group Gb, and an opening S disposed between the front group Gf and the rear group Gb. In the optical system 1 that is rotationally symmetric about the central axis 2 in the included cross section, the rear group Gb is disposed on the image plane 5 side of the aperture S, and the rear group 1 as a rear group transparent medium having a refractive index larger than 1. The rear first group transparent medium Lb includes the rear first group first transmission surface 21 as the rear group first transmission surface disposed on the central axis 2 in the vicinity of the opening S, and the rear first group first transmission first. A rear first group first reflecting surface 22 as a rear group first reflecting surface which is disposed on the image surface side from the transmitting surface 21 and has a concave surface facing the image surface side, and opposite to the image surface from the rear first group first reflecting surface 22. The rear first group second reflecting surface 23 as a rear group second reflecting surface with the concave surface facing the image surface side, and the rear first group second reflecting surface 23 after being disposed closer to the image surface side A rear first group first transmission surface 21, a rear first group first reflection surface 22, a rear first group second reflection surface 23, and a rear first group. The second transmission surface 24 is formed of a spherical surface, and the light beam incident on the transparent medium L passes through the aperture S in the order of forward ray tracing, enters the transparent medium L through the rear first group first transmission surface 21, and the rear 1 Reflected by the first group reflecting surface 22 on the side opposite to the image surface 5, reflected by the rear first group second reflecting surface 23 toward the image surface 5, and then passed through the rear first group second transmitting surface 24 from the transparent medium L. The first optical path A that is substantially Z-shaped to the outside of the first optical path A is configured, and at least the rear first group first reflecting surface 22 and the rear first group second reflecting surface 23 of the first optical path A are located on the central axis 2. On the other hand, it is configured only on one side, and an intermediate image is not formed in the first optical path A, but is formed in an annular shape on the image plane 5.

中心軸２上の物体側から光路順で、開口Ｓ及びその近傍に配置された後１群第１透過面２１、後１群第１反射面２２、後１群第２反射面２３、後１群第２透過面２４の順に配置され、後１群第１反射面２２と後１群第２反射面２３は共に像側に凹面を向け配置されていることが重要である。 Rear group 1 first transmission surface 21, rear group 1 first reflection surface 22, rear group 1 second reflection surface 23, rear 1 disposed in the vicinity of the aperture S in the order of the optical path from the object side on the central axis 2. It is important that they are arranged in the order of the group second transmission surface 24, and the rear first group first reflection surface 22 and the rear first group second reflection surface 23 are both arranged with the concave surface facing the image side.

開口Ｓは物体側の後１群第１透過面２１近傍にあることが重要で、開口Ｓを本発明の後１群透明媒体Ｌｂの像側に配置すると、非点収差が大きく発生しフラットな像を形成することが出来なくなる。また、射出主光線傾角が大きくなってしまい、テレセン性が悪くなる。さらに、後１群第１透過面２１と後１群第２反射面２３の有効径の干渉が起き、画角を大きく取ることが出来なくなってしまう。 It is important that the aperture S is in the vicinity of the rear first group first transmission surface 21 on the object side. If the aperture S is disposed on the image side of the rear first group transparent medium Lb of the present invention, astigmatism is greatly generated and flat. An image cannot be formed. Moreover, the emission chief ray inclination angle becomes large, and telecentricity deteriorates. Furthermore, interference between the effective diameters of the rear first group first transmission surface 21 and the rear first group second reflection surface 23 occurs, and it becomes impossible to obtain a large angle of view.

次に、後１群第１反射面２２と後１群第２反射面２３は像側に凹面を向け、さらに後１群第１反射面２２と後１群第２反射面２３の間の光路は回転対称軸を跨ぐことなく片側で構成され、Ｚ字光路になっていることが重要である。 Next, the rear first group first reflecting surface 22 and the rear first group second reflecting surface 23 face the concave surface toward the image side, and further the optical path between the rear first group first reflecting surface 22 and the rear first group second reflecting surface 23. It is important that is constructed on one side without straddling the rotational symmetry axis and has a Z-shaped optical path.

この配置により物体側から光路順に負、正のパワー配置になり、所謂レトロフォーカス
構成にすることが可能となり、広画角化が可能となる。また、この配置により光学系の主点を物体側に配置することが可能となり、Ｆバックを取ることが可能となる。さらに、光路途中で中間像を形成しない為に、光学系を小型にすることが可能である。 With this arrangement, a negative and positive power arrangement is made in order of the optical path from the object side, so that a so-called retrofocus configuration can be achieved, and a wide angle of view can be achieved. In addition, this arrangement makes it possible to arrange the principal point of the optical system on the object side, and to obtain an F-back. Furthermore, since an intermediate image is not formed in the middle of the optical path, the optical system can be reduced in size.

さらに、透過面の間に反射面を配置することにより、反射面を内部反射面で構成することにより、像面湾曲なので収差の発生を少なくすることが可能となる。また、後１群第１反射面２２に当る光線の傾きが空気中より小さくなりなるので、広画角にも良い結果をもたらす。 Further, by disposing the reflecting surface between the transmitting surfaces, the reflecting surface is configured by the internal reflecting surface, and hence the occurrence of aberration can be reduced because of the field curvature. In addition, since the inclination of the light ray that strikes the rear first group first reflecting surface 22 becomes smaller than that in the air, a good result is obtained for a wide angle of view.

さらに、後１群第１反射面２２は画角の広い光線は全反射により反射するように構成し、画角中心付近の後１群第１反射面２２で全反射しない入射角の光線を反射させるように、後１群第１反射面２２の中心部に反射コーティング４ａすることが好ましい。これにより画角中心部の映像も撮像することが可能となる。さらに後１群第１反射面２２周辺部は全反射するために、この部分は反射コーティングを行わないことが望ましい。これにより中心部分の光線が光学系から射出するのを妨げることがなくなる。 Further, the rear first group first reflecting surface 22 is configured so that light rays having a wide angle of view are reflected by total reflection, and light rays having incident angles that are not totally reflected by the rear first group first reflecting surface 22 near the center of the angle of view are reflected. It is preferable to apply the reflective coating 4 a to the central portion of the rear first group first reflective surface 22 so as to make it. As a result, it is also possible to capture an image of the center of the angle of view. Further, since the periphery of the rear first group first reflecting surface 22 is totally reflected, it is desirable that no reflective coating is applied to this portion. As a result, the central light beam is not prevented from exiting from the optical system.

さらに、後１群第１透過面２１と後１群第２反射面２３は透明媒体Ｌの物体側に近接して配置することが好ましい。これにより相互の面での光線の干渉が減り、広い画角を確保することが可能となる。 Further, it is preferable that the rear first group first transmission surface 21 and the rear first group second reflection surface 23 be disposed close to the object side of the transparent medium L. Thereby, the interference of the light rays on the mutual surfaces is reduced, and a wide angle of view can be secured.

さらに、後１群第１反射面２２と後１群第２透過面２４は透明媒体Ｌの像面５側に近接して配置することが好ましい。これにより透明媒体Ｌと像面５を短くすることが可能となり。光学系全長を短くすることが可能となる。 Further, it is preferable that the rear first group first reflecting surface 22 and the rear first group second transmitting surface 24 be arranged close to the image surface 5 side of the transparent medium L. As a result, the transparent medium L and the image plane 5 can be shortened. The total length of the optical system can be shortened.

さらに、後１群第２反射面２３は周辺部に反射コーティング４ｂを行うことが望ましく、中心部分は後１群第１透過面２１又は開口Ｓを配置する関係から、反射コーティングしないことが望ましい。 Further, the rear first group second reflecting surface 23 is desirably provided with a reflective coating 4b in the peripheral portion, and the central portion is preferably not subjected to the reflective coating because the rear first group first transmitting surface 21 or the opening S is disposed.

さらに好ましくは、後１群第１反射面２２と後１群第２透過面２４を同一場所、同一形状で構成することが好ましい。この構成により、後１群第１反射面２２に部分的に全反射を使うことが可能となり光学系の画角を広く取れる。 More preferably, the rear first group first reflecting surface 22 and the rear first group second transmitting surface 24 are preferably configured in the same place and in the same shape. With this configuration, it is possible to partially use total reflection on the rear first group first reflecting surface 22 and a wide angle of view of the optical system can be obtained.

さらに好ましくは、後１群第１透過面２１と後１群第２反射面２３を同一場所、同一形状で構成することが望ましい。この構成により、加工性がよくなる。 More preferably, it is desirable that the rear first group first transmission surface 21 and the rear first group second reflection surface 23 be configured in the same place and in the same shape. With this configuration, workability is improved.

また、前群Ｇｆは、中心軸２の周りで回転対称な屈折率が１より大きい前群透明媒体Ｌｆを有し、前群透明媒体Ｌｆは、光路順に、前群第１透過面１１と、前群第１透過面１１と中心軸２を挟んで反対側で像面５側に配置された前群第１反射面１２と、前群第１反射面１２と中心軸２に対して同じ側で前群第１反射面１２より像面５と反対側に配置された前群第２反射面１３と、前群第２反射面１３より像面５側に配置された前群第２透過面１４と、を有し、前群透明媒体Ｌｆに入射する光束は、順光線追跡の順に、前群第１透過面１１を経て前群透明媒体Ｌｆ内に入り、前群第１反射面１２で像面５と反対側に反射され、前群第２反射面１３で像面５側に反射され、前群第２透過面１４を経て前群透明媒体Ｌｆから像面５側に外へ出る光路を構成することが好ましい。 Further, the front group Gf has a front group transparent medium Lf having a refractive index rotationally symmetric around the central axis 2 greater than 1, and the front group transparent medium Lf is arranged in the optical path order with the front group first transmission surface 11; The front group first reflecting surface 12 disposed on the opposite side of the front group first transmitting surface 11 and the central axis 2 on the image plane 5 side, and the same side with respect to the front group first reflecting surface 12 and the central axis 2 The front group second reflecting surface 13 disposed on the opposite side of the image surface 5 from the front group first reflecting surface 12, and the front group second transmitting surface disposed on the image surface 5 side from the front group second reflecting surface 13. , And enters the front group transparent medium Lf through the front group first transmission surface 11 in the order of forward ray tracing, and enters the front group first reflection surface 12 in the order of forward ray tracing. An optical path that is reflected on the side opposite to the image surface 5, reflected on the image surface 5 side by the front group second reflecting surface 13, and exits from the front group transparent medium Lf to the image surface 5 side through the front group second transmitting surface 14. Be configured are preferred.

また、前群Ｇｆは、中心軸の周りで回転対称な屈折率が１より大きい前群透明媒体Ｌｆを有し、前群透明媒体Ｌｆは、光路順に、前群第１透過面１１と、前群第１透過面１１と中心軸２を挟んで反対側で像面５側に配置された前群第１反射面１２と、前群第１反射面１２と中心軸２に対して反対側で前群第１反射面１２より像面５と反対側に配置された前群第２反射面１３と、前群第２反射面１３より像面５側に配置された前群第２透過面１４
と、を有し、前群透明媒体Ｌｆに入射する光束は、順光線追跡の順に、前群第１透過面１１を経て前群透明媒体Ｌｆ内に入り、前群第１反射面１２で像面５と反対側に反射され、前群第２反射面１３で像面５側に反射され、前群第２透過面１４を経て前群透明媒体Ｌｆから像面５側に外へ出る光路を構成することが好ましい。 The front group Gf includes a front group transparent medium Lf having a refractive index that is rotationally symmetric about the central axis and greater than 1. The front group transparent medium Lf includes the front group first transmission surface 11 and the front group transparent surface Lf in the optical path order. The front group first reflective surface 12 disposed on the image plane 5 side on the opposite side of the group first transmission surface 11 and the central axis 2, and on the opposite side to the front group first reflective surface 12 and the central axis 2. A front group second reflecting surface 13 disposed on the opposite side of the image surface 5 from the front group first reflecting surface 12, and a front group second transmitting surface 14 disposed on the image surface 5 side from the front group second reflecting surface 13.
, And enters the front group transparent medium Lf through the front group first transmission surface 11 in the order of forward ray tracing, and is imaged on the front group first reflection surface 12. An optical path reflected on the side opposite to the surface 5, reflected on the image surface 5 side by the front group second reflecting surface 13, and exits from the front group transparent medium Lf to the image surface 5 side via the front group second transmitting surface 14. It is preferable to configure.

また、前群Ｇｆは、中心軸２の周りで回転対称な屈折率が１より大きい前群透明媒体Ｌｆを有し、前群透明媒体Ｌｆは、光路順に、前群第１透過面１１と、前群第１透過面１１と中心軸２を挟んで反対側で像面５と反対側に配置された前群第１反射面１２と、前群第１反射面１２より像面５側に配置された前群第２透過面１４と、を有し、前群透明媒体Ｌｆに入射する光束は、順光線追跡の順に、前群第１透過面１１を経て前群透明媒体Ｌｆ内に入り、前群第１反射面１２で像面側に反射され、前群第２透過面１４を経て前群透明媒体Ｌｆから像面５側に外へ出る光路を構成することが好ましい。 Further, the front group Gf has a front group transparent medium Lf having a refractive index rotationally symmetric around the central axis 2 greater than 1, and the front group transparent medium Lf is arranged in the optical path order with the front group first transmission surface 11; The front group first reflecting surface 12 disposed on the opposite side of the front group first transmitting surface 11 and the central axis 2 on the opposite side to the image surface 5, and disposed on the image surface 5 side from the front group first reflecting surface 12. The light flux incident on the front group transparent medium Lf enters the front group transparent medium Lf through the front group first transmission surface 11 in the order of forward ray tracing, It is preferable to configure an optical path that is reflected by the front group first reflecting surface 12 to the image surface side and exits from the front group transparent medium Lf to the image surface 5 side through the front group second transmitting surface 14.

また、最大像高をＩmax、前記透明媒体の外径をＤとするとき、
０．５＜Ｄ／（２×Ｉmax）＜１０・・・（１）
なる条件を満足することが望ましい。 When the maximum image height is Imax and the outer diameter of the transparent medium is D,
0.5 <D / (2 × Imax) <10 (1)
It is desirable to satisfy the following conditions.

条件式（１）は、下限を超えるとテレセン性が悪くなり特にＣＣＤ等の撮像素子を利用して撮像する場合に周辺光量不足を起こす。上限を超えると光学系の外径が大きくなりすぎ光学系が大型になってしまう。 When conditional expression (1) exceeds the lower limit, the telecentricity is deteriorated, and particularly when the image is picked up using an image pickup device such as a CCD, the peripheral light amount is insufficient. If the upper limit is exceeded, the outer diameter of the optical system becomes too large and the optical system becomes large.

また、最大像高をＩmax、前記開口から前記像面までの距離をＬとするとき、
０．５＜Ｌ／（２×Ｉmax）＜１０・・・（２）
なる条件を満足することが望ましい。 When the maximum image height is Imax and the distance from the opening to the image plane is L,
0.5 <L / (2 × Imax) <10 (2)
It is desirable to satisfy the following conditions.

条件式（２）は、像高に対する光学系全長を規定するものであり、下限を超えるとやはりテレセン性が悪くなり周辺光量不足を起こす。上限を超えると全長が長くなりすぎ、小型の光学系を構成することはできない。 Conditional expression (2) defines the total length of the optical system with respect to the image height. If the lower limit is exceeded, the telecentricity also deteriorates and the peripheral light quantity is insufficient. If the upper limit is exceeded, the total length becomes too long, and a compact optical system cannot be constructed.

また、後１群第１反射面２２の曲率をＲ１、後１群第２反射面２３の曲率をＲ２とするとき、
０．２＜Ｒ１／Ｒ２＜５・・・（３）
なる条件を満足することが望ましい。 When the curvature of the rear first group first reflecting surface 22 is R1, and the curvature of the rear first group second reflecting surface 23 is R2,
0.2 <R1 / R2 <5 (3)
It is desirable to satisfy the following conditions.

条件式（３）は、二つの反射面のパワーの比を規定しているものであり、下限を超えると、後１群第１反射面２２の曲率半径が小さくなり、後１群第２反射面２３の正のパワーに比べて、後１群第１反射面２２の負のパワーが大きくなり光学系の全長を短くすることが出来ない。上限を超えると、後１群第２反射面２３の曲率が小さくなり後１群第２反射面２３の正のパワーが大きくなりすぎ、物体側に凸の像面湾曲が大きく発生する。 Conditional expression (3) defines the ratio of the power of the two reflecting surfaces. When the lower limit is exceeded, the radius of curvature of the rear first group first reflecting surface 22 becomes smaller, and the rear first group second reflecting. Compared with the positive power of the surface 23, the negative power of the rear first group first reflecting surface 22 becomes larger, and the total length of the optical system cannot be shortened. If the upper limit is exceeded, the curvature of the rear first group second reflecting surface 23 becomes smaller, the positive power of the rear first group second reflecting surface 23 becomes too large, and a large curvature of field on the object side occurs.

なお、すべての実施例は球面で構成されているが、通常の非球面で構成することも可能である。また物体側の平行平面は、光学系保護用のものであり。無くてもよい。像側の平行平面は撮像素子保護用のものであり、無くても良い。 In addition, although all the embodiments are configured with spherical surfaces, they can also be configured with ordinary aspherical surfaces. The parallel plane on the object side is for protecting the optical system. There is no need. The parallel plane on the image side is for protecting the image sensor and may be omitted.

以下に、本発明の光学系の実施例１〜４を説明する。これら光学系の構成パラメータは後記する。 Examples 1 to 4 of the optical system of the present invention will be described below. The configuration parameters of these optical systems will be described later.

座標系は、順光線追跡において、例えば図１に示すように、絞り面Ｓが中心軸２と交差する点を偏心光学面の原点Ｏとし、中心軸２に直交する方向をＹ軸方向とし、図１の紙面内をＹ−Ｚ平面とする。そして、図１の像面５側の方向をＺ軸正方向とし、Ｙ軸、Ｚ軸と
右手直交座標系を構成する軸をＸ軸正方向とする。 In the forward ray tracing, for example, as shown in FIG. 1, the coordinate system uses the point where the diaphragm surface S intersects the central axis 2 as the origin O of the decentered optical surface, and the direction perpendicular to the central axis 2 as the Y-axis direction. A plane in FIG. 1 is a YZ plane. The direction on the image plane 5 side in FIG. 1 is the Z axis positive direction, and the Y axis, the Z axis, and the axis constituting the right-handed orthogonal coordinate system are the X 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１の原点Ｏ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１の原点Ｏ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 decentering amount from the origin O of the optical system 1 of 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 1 The inclination angles (α, β, γ (°), respectively) of the coordinate system defining the respective planes centered on the X axis, the Y axis, and the Z axis of the coordinate system defined by the origin O 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、各実施例の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。 Further, among the optical action surfaces constituting the optical system of each embodiment, when a specific surface and a subsequent surface constitute a coaxial optical system, a surface interval is given, in addition, the curvature radius of the surface, The refractive index and Abbe number of the medium are given according to conventional methods.

また、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、基準面からの偏心量で表わす。 In addition, 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. As described above, the eccentricity of each surface is expressed by the amount of eccentricity from the reference surface.

なお、非球面は、以下の定義式で与えられる回転対称非球面である。
Ｚ＝（Ｙ²／Ｒ）／［１＋｛１−（１＋ｋ）Ｙ²／Ｒ²｝^{1 /2}］
＋ａＹ⁴＋ｂＹ⁶＋ｃＹ⁸＋ｄＹ¹⁰＋・・・
・・・（ａ）
ただし、Ｚを軸とし、Ｙを軸と垂直な方向にとる。ここで、Ｒは近軸曲率半径、ｋは円錐定数、ａ、ｂ、ｃ、ｄ、…はそれぞれ４次、６次、８次、１０次の非球面係数である。この定義式のＺ軸が回転対称非球面の軸となる。 The aspheric surface is a rotationally symmetric aspheric surface given by the following definition.
^{Z = (Y 2 / R)} / [1+ {1- (1 + k) Y 2 / R 2} 1/2]
+ AY ⁴ + bY ⁶ + cY ⁸ + dY ¹⁰ +...
... (a)
However, Z is taken as an axis, and Y is taken in a direction perpendicular to the axis. Here, R is a paraxial radius of curvature, k is a conic constant, a, b, c, d,... Are fourth-order, sixth-order, eighth-order, and tenth-order aspherical coefficients, respectively. The Z axis of this defining formula is the axis of a rotationally symmetric aspherical surface.

また、拡張回転自由曲面は、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 is a rotationally symmetric surface given by the following definition.

まず、図２に示すように、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, as shown in FIG. 2, 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Ｙ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 (Y negative direction if negative), and then the rotationally symmetric surface is rotated by rotating the translated curve around the Z axis. 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。 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.

なお、Ｚ軸を中心軸に持つ円錐面は拡張回転自由曲面の１つとして与えられ、ＲＹ＝∞，Ｃ₁，Ｃ₂，Ｃ₃，Ｃ₄，Ｃ₅，…＝０とし、θ＝（円錐面の傾き角）、Ｒ＝（Ｘ−Ｚ面内での底面の半径）として与えられる。 A conical surface having the Z axis as the central axis is given as one of the extended rotation free-form surfaces, and RY = ∞, C ₁ , C ₂ , C ₃ , C ₄ , C ₅ ,... = 0, and θ = ( The inclination angle of the conical surface), R = (the radius of the bottom surface in the XZ plane).

実施例１の光学系１の中心軸２に沿ってとった断面図を図３に示す。また、この実施例の光学系全体の横収差図を図４に示す。この横収差図において、中央に示された角度は、（水平方向画角、垂直方向の画角）を示し、その画角における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。なお、マイナスの画角は、水平方向画角については、Ｙ軸正方向を向いて右回りの角度、垂直方向画角については、Ｘ軸正方向を向いて右回りの角度を意味する。以下、同じ。 A cross-sectional view taken along the central axis 2 of the optical system 1 of Example 1 is shown in FIG. Further, FIG. 4 shows a lateral aberration diagram of the entire optical system of this example. In this lateral aberration diagram, the angle shown at the center indicates (horizontal field angle, vertical field angle), and the lateral aberrations in the Y direction (meridional direction) and X direction (sagittal direction) at that field angle. Show. Note that a negative field angle means a clockwise angle in the Y-axis positive direction for the horizontal field angle, and a clockwise angle in the X-axis positive direction for the vertical field angle. same as below.

本実施例は、光学系１の中心軸２に同心に回転対称な屈折率が１より大きい後１群透明媒体Ｌｂの透過面及び反射面を、光路内で一部共通に使用する球面で構成し、該後１群透明媒体Ｌｂの前群Ｇｆとして前群透明媒体Ｌｆを配置した例である。 In this embodiment, the transmission surface and the reflection surface of the first group of transparent media Lb having a refractive index which is concentric and rotationally symmetric with respect to the central axis 2 of the optical system 1 is larger than 1. In this example, the front group transparent medium Lf is disposed as the front group Gf of the first group transparent medium Lb.

光学系１は、前群Ｇｆと、後群Ｇｂと、前群Ｇｆと後群Ｇｂの間で中心軸２に同軸に配置された開口Ｓとからなり、後群Ｇｂは、後１群Ｇｂ１と後２群Ｇｂ２からなる。 The optical system 1 includes a front group Gf, a rear group Gb, and an opening S that is disposed coaxially with the central axis 2 between the front group Gf and the rear group Gb. The rear group Gb includes a rear group Gb1 and a rear group Gb1. It consists of back 2 groups Gb2.

前群Ｇｆは、中心軸２の周りで回転対称な屈折率が１より大きい前群透明媒体Ｌｆからなる。前群透明媒体Ｌｆは、中心軸２の周りで回転対称な屈折率が１より大きい樹脂等からなり、遠方からの光束が入射し拡張回転自由曲面からなる前群第１透過面１１と、前群第１透過面１１と中心軸２を挟んで反対側で前群第１透過面１１より像面５側に配置されていて、前群第１透過面１１から入射した光束が入射し拡張回転自由曲面からなる前群第１反射面１２と、前群第１反射面１２と中心軸２に対して同じ側で前群第１反射面１２より像面５と反対側に配置され、前群第１反射面１２で反射された光束が入射し拡張回転自由曲面からなる前群第２反射面１３と、後群Ｇｂに面していて、前群第２反射面１３で反射された光束が入射し球面からなる前群第２透過面１４とからなる。 The front group Gf is composed of a front group transparent medium Lf having a refractive index that is rotationally symmetric about the central axis 2 and greater than 1. The front group transparent medium Lf is made of a resin or the like having a rotationally symmetric refractive index greater than 1 around the central axis 2, and a front group first transmission surface 11 made of an extended rotation free-form surface through which a light beam from a distance is incident, It is arranged on the opposite side of the group first transmission surface 11 and the central axis 2 from the front group first transmission surface 11 on the image plane 5 side, and the light beam incident from the front group first transmission surface 11 is incident and expanded. The front group first reflecting surface 12 made of a free-form surface, and disposed on the same side of the front group first reflecting surface 12 and the central axis 2 as the front group first reflecting surface 12 and on the side opposite to the image plane 5, The light beam reflected by the first reflecting surface 12 is incident and the front group second reflecting surface 13 formed of an extended rotation free-form surface and the rear group Gb are faced and the light beam reflected by the front group second reflecting surface 13 is reflected. It consists of the front group 2nd transmission surface 14 which injects and consists of spherical surfaces.

後１群Ｇｂ１は、中心軸２の周りで回転対称な屈折率が１より大きい後１群透明媒体Ｌｂからなる。後１群透明媒体Ｌｂは、中心軸２上で球面からなる後１群第１透過面２１と、後１群第１透過面２１に対して像側に形成され、一部を反射コーティング４ａし、負のパワーをもつ像面側に凹面を向けた後１群第１反射面２２と、後１群第１反射面２２に対して像面５と反対側に配置され、反射コーティング４ｂし、正のパワーをもつ像面側に凹面を向けた後１群第２反射面２３と、後１群第２反射面２３より像面５側に配置され、負のパワーをもつ後１群第２透過面２４とを有する。後１群第１透過面２１と後１群第２反射面２３は、同一位置同一形状からなり、後１群第１反射面２２と後１群第２透過面２４は、同一位置同一形状からなる。 The rear first group Gb1 is composed of a rear first group transparent medium Lb whose refractive index rotationally symmetric about the central axis 2 is greater than one. The rear first group transparent medium Lb is formed on the image side with respect to the rear first group first transmission surface 21 and the rear first group first transmission surface 21 formed of a spherical surface on the central axis 2, and a part of the rear first group transparent medium Lb has a reflective coating 4 a. A rear first group first reflecting surface 22 having a concave surface directed to the image surface side having a negative power, and disposed on the opposite side of the rear first group first reflecting surface 22 from the image surface 5, and a reflective coating 4b. The rear first group second reflecting surface 23 with the concave surface facing the image surface side having positive power, and the rear first group second reflecting surface 23 arranged on the image surface 5 side from the rear first group second reflecting surface 23 and having negative power. And a transmission surface 24. The rear first group first transmission surface 21 and the rear first group second reflection surface 23 have the same shape at the same position, and the rear first group first reflection surface 22 and the rear first group second transmission surface 24 have the same shape at the same position. Become.

後２群Ｇｂ２は、中心軸２の周りで回転対称な屈折率が１より大きい後２群カバーガラスＣｂ２からなる。後２群カバーガラスＣｂ２は、平行平板からなり、後２群第１透過面３１と、後２群第１透過面３１に対して像側に形成される後２群第２透過面３２とを有する。 The rear second group Gb2 is composed of a rear second group cover glass Cb2 having a rotationally symmetric refractive index greater than 1 around the central axis 2. The rear second group cover glass Cb2 is formed of a parallel plate, and includes a rear second group first transmission surface 31 and a rear second group second transmission surface 32 formed on the image side with respect to the rear second group first transmission surface 31. Have.

光学系１は、光路Ａを形成する。光学系１の物体面３から入射する光束は、前群透明媒体Ｌｆの前群第１透過面１１を経て、中心軸２を横切って前群第１透過面１１と反対側の前群第１反射面１２で後群Ｇｂから離れるように上方へ反射されて、前群第１反射面１２と中心軸２に対して同じ側で後群Ｇｂからより離れた側に位置している前群第２反射面１３で後群Ｇｂ方向へ再度反射され、射出面の前群第２透過面１４を経て前群透明媒体Ｌｆから外に出る。 The optical system 1 forms an optical path A. The light beam incident from the object plane 3 of the optical system 1 passes through the front group first transmission surface 11 of the front group transparent medium Lf, crosses the central axis 2, and is on the front group first side opposite to the front group first transmission surface 11. The front surface is reflected upward by the reflecting surface 12 away from the rear group Gb, and is located on the same side of the front group first reflecting surface 12 and the central axis 2 and further away from the rear group Gb. The light is reflected again by the second reflecting surface 13 in the rear group Gb direction, and exits from the front group transparent medium Lf via the front group second transmitting surface 14 of the exit surface.

その後、前群透明媒体Ｌｆと後１群透明媒体Ｌｂの間で中心軸２に同軸に配置された開口Ｓとを経て後１群透明媒体Ｌｂ内に入る。後１群透明媒体Ｌｂでは、後１群第１透過面２１を経て入り、後１群第１反射面２２で一部が反射コーティング４ａ、一部が全反射により像面５と反対側に反射され、後１群第２反射面２３で反射コーティング４ｂにより像面５側に反射され、後１群第２透過面２４を経て後１群透明媒体Ｌｂから外に出る略Ｚ字状の光路を有する。その後、後２群カバーガラスＣｂ２の後２群第１透過面３１と後２群第２透過面３２を経て、像面５の中心軸２から外れた半径方向の所定位置に円環状に結像する。 Thereafter, the light enters the rear first group transparent medium Lb through the opening S disposed coaxially with the central axis 2 between the front group transparent medium Lf and the rear first group transparent medium Lb. In the rear first group transparent medium Lb, it enters through the rear first group first transmission surface 21, and a part of the rear first group first reflection surface 22 is reflected on the reflective coating 4 a, and a part is reflected to the opposite side to the image surface 5 by total reflection. A substantially Z-shaped optical path is reflected from the rear first group second reflecting surface 23 to the image surface 5 side by the reflective coating 4b and exits from the rear first group second transparent medium Lb via the rear first group second transmitting surface 24. Have. Thereafter, an image is formed in an annular shape at a predetermined radial position away from the central axis 2 of the image plane 5 via the rear second group first transmission surface 31 and the rear second group second transmission surface 32 of the rear second group cover glass Cb2. To do.

この実施例１の仕様は、
全系の画角 50.00°〜360.0°
後群の画角 26.81°〜60.22°
入射瞳径 φ0.94mm
像の大きさ φ4.04mm〜φ7.83mm
である。 The specification of this Example 1 is
Angle of view of the entire system 50.00 ° to 360.0 °
Rear group angle of view 26.81 ° -60.22 °
Entrance pupil diameter 0.94mm
Image size φ4.04mm to φ7.83mm
It is.

実施例２の光学系１の中心軸２に沿ってとった断面図を図５に示す。また、この実施例の光学系全体の横収差図を図６に示す。 A sectional view taken along the central axis 2 of the optical system 1 of Example 2 is shown in FIG. Further, FIG. 6 shows a lateral aberration diagram of the entire optical system of this example.

本実施例は、光学系１の中心軸２に同心に回転対称な屈折率が１より大きい後群透明媒体Ｌｂの透過面及び反射面を、光路内で一部共通に使用する球面で構成し、該後群透明媒体Ｌｂの前群Ｇｆとして前群透明媒体Ｌｆを配置した例である。 In this embodiment, the transmission surface and the reflection surface of the rear group transparent medium Lb having a refractive index larger than 1 concentrically symmetric with respect to the central axis 2 of the optical system 1 are configured as spherical surfaces that are partially shared in the optical path. In this example, the front group transparent medium Lf is arranged as the front group Gf of the rear group transparent medium Lb.

光学系１は、前群Ｇｆと、後群Ｇｂと、前群Ｇｆと後群Ｇｂの間で中心軸２に同軸に配置された開口Ｓとからなり、後群Ｇｂは、第１群Ｇ１と第２群Ｇ２からなる。 The optical system 1 includes a front group Gf, a rear group Gb, and an aperture S that is coaxially disposed on the central axis 2 between the front group Gf and the rear group Gb. The rear group Gb includes the first group G1 and the rear group Gb. It consists of 2nd group G2.

前群Ｇｆは、中心軸２の周りで回転対称な屈折率が１より大きい前群透明媒体Ｌｆからなる。前群透明媒体Ｌｆは、中心軸２の周りで回転対称な屈折率が１より大きい樹脂等からなり、遠方からの光束が入射し拡張回転自由曲面からなる前群第１透過面１１と、前群第１透過面１１と中心軸２を挟んで反対側で前群第１透過面１１より像面５側に配置されていて、前群第１透過面１１から入射した光束が入射し拡張回転自由曲面からなる前群第１反射面１２と、前群第１反射面１２と中心軸１を挟んで反対側で前群第１反射面１２より像面５と反対側に配置され、前群第１反射面１２で反射された光束が入射し拡張回転自由曲面からなる前群第２反射面１３と、中心軸２上で後群Ｇｂに面していて前群第２反射面１３より像面５側に配置され、前群第２反射面１３で反射された光束が入射し球面からなる前群第２透過面１４とからなる。 The front group Gf is composed of a front group transparent medium Lf having a refractive index that is rotationally symmetric about the central axis 2 and greater than 1. The front group transparent medium Lf is made of a resin or the like having a rotationally symmetric refractive index greater than 1 around the central axis 2, and a front group first transmission surface 11 made of an extended rotation free-form surface through which a light beam from a distance is incident, It is arranged on the opposite side of the group first transmission surface 11 and the central axis 2 from the front group first transmission surface 11 on the image plane 5 side, and the light beam incident from the front group first transmission surface 11 is incident and expanded. The front group first reflecting surface 12 made of a free-form surface, and disposed on the opposite side of the front group first reflecting surface 12 and the image plane 5 on the opposite side of the front group first reflecting surface 12 with respect to the central axis 1, The front group second reflecting surface 13 formed of an extended rotation free-form surface by the incident light beam reflected by the first reflecting surface 12 and the rear group Gb on the central axis 2 and imaged from the front group second reflecting surface 13. It is arranged on the surface 5 side, and is composed of a front group second transmission surface 14 formed of a spherical surface upon incidence of a light beam reflected by the front group second reflection surface 13.

後１群Ｇｂ１は、中心軸２の周りで回転対称な屈折率が１より大きい後１群透明媒体Ｌｂからなる。後１群透明媒体Ｌｂは、中心軸２上で球面からなる後１群第１透過面２１と、後１群第１透過面２１に対して像側に形成され、一部を反射コーティング４ａし、負のパワーをもつ像面側に凹面を向けた後１群第１反射面２２と、後１群第１反射面２２に対して像面５と反対側に配置され、反射コーティング４ｂし、正のパワーをもつ像面側に凹
面を向けた後１群第２反射面２３と、後１群第２反射面２３より像面５側に配置され、負のパワーをもつ後１群第２透過面２４とを有する。後１群第１透過面２１と後１群第２反射面２３は、同一位置同一形状からなり、後１群第１反射面２２と後１群第２透過面２４は、同一位置同一形状からなる。 The rear first group Gb1 is composed of a rear first group transparent medium Lb whose refractive index rotationally symmetric about the central axis 2 is greater than one. The rear first group transparent medium Lb is formed on the image side with respect to the rear first group first transmission surface 21 and the rear first group first transmission surface 21 formed of a spherical surface on the central axis 2, and a part of the rear first group transparent medium Lb has a reflective coating 4 a. A rear first group first reflecting surface 22 having a concave surface directed to the image surface side having a negative power, and disposed on the opposite side of the rear first group first reflecting surface 22 from the image surface 5, and a reflective coating 4b. The rear first group second reflecting surface 23 with the concave surface facing the image surface side having positive power, and the rear first group second reflecting surface 23 arranged on the image surface 5 side from the rear first group second reflecting surface 23 and having negative power. And a transmission surface 24. The rear first group first transmission surface 21 and the rear first group second reflection surface 23 have the same shape at the same position, and the rear first group first reflection surface 22 and the rear first group second transmission surface 24 have the same shape at the same position. Become.

光学系１は、光路Ａを形成する。光路Ａにおいて、光学系１の物体面３から入射する光束は、前群第１透過面１１を経て前群透明媒体Ｌｆ内に入り、中心軸２を横切って前群第１透過面１１と反対側の前群第１反射面１２で後群Ｇｂから離れるように上方へ像面５と反対側に反射され、前群第１反射面１２と中心軸２に対して反対側で後群Ｇｂからより離れた側に位置している前群第２反射面１３で像面５側に反射され、射出面の前群第２透過面１４を経て前群透明媒体Ｌｆから外に出る。 The optical system 1 forms an optical path A. In the optical path A, the light beam incident from the object plane 3 of the optical system 1 enters the front group transparent medium Lf via the front group first transmission surface 11, crosses the central axis 2, and is opposite to the front group first transmission surface 11. The front front group first reflecting surface 12 is reflected upwardly away from the rear surface group Gb so as to be separated from the rear group Gb, and from the rear group Gb on the opposite side to the front group first reflecting surface 12 and the central axis 2. The light is reflected to the image surface 5 side by the front group second reflecting surface 13 located on the farther side, and exits from the front group transparent medium Lf via the front group second transmitting surface 14 of the exit surface.

その後、前群透明媒体Ｌｆと後１群透明媒体Ｌｂの間で中心軸２に同軸に配置された開口Ｓとを経て、後１群透明媒体Ｌｂ内に入る。後１群透明媒体Ｌｂでは、後１群第１透過面２１を経て入り、後１群第１反射面２２で一部が反射コーティング４ａ、他部が全反射により像面５と反対側に反射され、後１群第２反射面２３で反射コーティング４ｂにより像面５側に反射され、後１群第２透過面２４を経て後１群透明媒体Ｌｂから外に出る略Ｚ字状の光路を有する。その後、後２群カバーガラスＣｂ２の後２群第１透過面３１と後２群第２透過面３２を経て、像面５の中心軸２から外れた半径方向の所定位置に円環状に結像する。 Thereafter, the light enters the rear first group transparent medium Lb through the opening S disposed coaxially with the central axis 2 between the front group transparent medium Lf and the rear first group transparent medium Lb. In the rear first group transparent medium Lb, it enters through the rear first group first transmission surface 21, and part of the rear first group first reflection surface 22 is reflected on the opposite side of the image surface 5 by the total reflection. A substantially Z-shaped optical path is reflected from the rear first group second reflecting surface 23 to the image surface 5 side by the reflective coating 4b and exits from the rear first group second transparent medium Lb via the rear first group second transmitting surface 24. Have. Thereafter, an image is formed in an annular shape at a predetermined radial position away from the central axis 2 of the image plane 5 via the rear second group first transmission surface 31 and the rear second group second transmission surface 32 of the rear second group cover glass Cb2. To do.

この実施例２の仕様は、
全系の画角 80.00°〜360°
後群の画角 22.92°〜58.29°
入射瞳径 φ0.10mm
像の大きさ φ3.58mm〜φ7.91mm
である。 The specification of Example 2 is
Angle of view of the entire system 80.00 ° to 360 °
Rear group angle of view 22.92 °-58.29 °
Entrance pupil diameter φ0.10mm
Image size φ3.58mm to φ7.91mm
It is.

実施例３の光学系１の中心軸２に沿ってとった断面図を図７に示す。また、この実施例の光学系全体の横収差図を図８に示す。 A sectional view taken along the central axis 2 of the optical system 1 of Example 3 is shown in FIG. Further, FIG. 8 shows a lateral aberration diagram of the entire optical system of this example.

光学系１は、前群Ｇｆと、後群Ｇｂと、前群Ｇｆと後群Ｇｂの間で中心軸２に同軸に配置された開口Ｓとからなる。 The optical system 1 includes a front group Gf, a rear group Gb, and an opening S disposed coaxially with the central axis 2 between the front group Gf and the rear group Gb.

前群Ｇｆは、中心軸２の周りで回転対称な屈折率が１より大きい前群透明媒体Ｌｆからなる。前群透明媒体Ｌｆは、中心軸２の周りで回転対称な屈折率が１より大きい樹脂等からなり、遠方からの光束が入射し拡張回転自由曲面からなる前群第１透過面１１と、前群第１透過面１１と中心軸２を挟んで反対側で前群第１透過面１１より像面５と反対側に配置されていて、前群第１透過面１１から入射した光束が入射し拡張回転自由曲面からなる前群第１反射面１２と、後群Ｇｂに面していて中心軸２上で前群第１反射面１２より像面５側に配置され、前群第１反射面１２で反射された光束が入射し非球面からなる前群第２
透過面１４とからなる。 The front group Gf is composed of a front group transparent medium Lf having a refractive index that is rotationally symmetric about the central axis 2 and greater than 1. The front group transparent medium Lf is made of a resin or the like having a rotationally symmetric refractive index greater than 1 around the central axis 2, and a front group first transmission surface 11 made of an extended rotation free-form surface through which a light beam from a distance is incident, It is arranged on the opposite side of the group first transmission surface 11 and the central axis 2 on the opposite side of the image plane 5 from the front group first transmission surface 11, and the light beam incident from the front group first transmission surface 11 is incident. The front group first reflecting surface 12 made of an extended rotation free-form surface, and the rear group Gb facing the rear group Gb and arranged on the image plane 5 side from the front group first reflecting surface 12 on the central axis 2, and the front group first reflecting surface The second light beam reflected by 12 is incident and the front group is made of an aspheric surface.
And a transmission surface 14.

後群Ｇ１は、中心軸２の周りで回転対称な屈折率が１より大きい後１群透明媒体Ｌｂからなる。後１群透明媒体Ｌｂは、中心軸２上で球面からなる後１群第１透過面２１と、後１群第１透過面２１に対して像側に形成され、一部を反射コーティング４ａし、負のパワーをもつ像面側に凹面を向けた後１群第１反射面２２と、後１群第１反射面２２に対して像面５と反対側に配置され、一部を反射コーティング４ｂし、正のパワーをもつ後１群第２反射面２３と、後１群第２反射面２３より像面５側に配置され、負のパワーをもつ後１群第２透過面２４を有する。後１群第１透過面２１と後１群第２反射面２３は、同一位置同一形状からなり、後１群第１反射面２２と後１群第２透過面２４は、同一位置同一形状からなる。 The rear group G1 is composed of a rear first group transparent medium Lb whose refractive index rotationally symmetric about the central axis 2 is greater than 1. The rear first group transparent medium Lb is formed on the image side with respect to the rear first group first transmission surface 21 and the rear first group first transmission surface 21 formed of a spherical surface on the central axis 2, and a part of the rear first group transparent medium Lb has a reflective coating 4 a. A rear first group first reflecting surface 22 with a concave surface facing the image surface side having negative power, and a rear first group first reflecting surface 22 opposite to the image surface 5 and partly reflecting coating 4b, the rear first group second reflecting surface 23 having a positive power, and the rear first group second transmitting surface 24 having a negative power and disposed on the image plane 5 side from the rear first group second reflecting surface 23. . The rear first group first transmission surface 21 and the rear first group second reflection surface 23 have the same shape at the same position, and the rear first group first reflection surface 22 and the rear first group second transmission surface 24 have the same shape at the same position. Become.

光学系１は、光路Ａを形成する。光路Ａにおいて、光学系１の物体面３から入射する光束は、前群第１透過面１１を経て前群透明媒体Ｌｆ内に入り、中心軸２を横切って前群第１透過面１１と反対側の前群第１反射面１２で後群Ｇｂに向かって下方へ像面５側に反射され、射出面の前群第２透過面１４を経て前群透明媒体Ｌｆから外に出る。 The optical system 1 forms an optical path A. In the optical path A, the light beam incident from the object plane 3 of the optical system 1 enters the front group transparent medium Lf via the front group first transmission surface 11, crosses the central axis 2, and is opposite to the front group first transmission surface 11. The first front reflecting surface 12 on the side is reflected downward toward the rear group Gb toward the image surface 5 side, and exits from the front group transparent medium Lf via the front group second transmitting surface 14 on the exit surface.

その後、前群透明媒体Ｌｆと後１群透明媒体Ｌｂの間で中心軸２に同軸に配置された開口Ｓとを経て、後１群透明媒体Ｌｂ内に入る。後１群透明媒体Ｌｂでは、後１群第１透過面２１を経て入り、後１群第１反射面２２で一部が反射コーティング４ａ、他部が全反射により像面５と反対側に反射され、後１群第２反射面２３で反射コーティング４ｂにより像面５側に反射され、後１群第２透過面２４を経て後１群透明媒体Ｌｂから外に出る略Ｚ字状の光路を有する。その後、像面５の中心軸２から外れた半径方向の所定位置に円環状に結像する。 Thereafter, the light enters the rear first group transparent medium Lb through the opening S disposed coaxially with the central axis 2 between the front group transparent medium Lf and the rear first group transparent medium Lb. In the rear first group transparent medium Lb, it enters through the rear first group first transmission surface 21, and part of the rear first group first reflection surface 22 is reflected on the opposite side of the image surface 5 by the total reflection. A substantially Z-shaped optical path is reflected from the rear first group second reflecting surface 23 to the image surface 5 side by the reflective coating 4b and exits from the rear first group second transparent medium Lb via the rear first group second transmitting surface 24. Have. Thereafter, an image is formed in an annular shape at a predetermined position in the radial direction deviating from the central axis 2 of the image plane 5.

この実施例３の仕様は、
全系の画角 60.00°×360°
後群の画角 13.52°〜52.56°
後群の入射瞳径 φ1.00mm
像の大きさ φ2.44mm〜φ7.95mm
である。 The specification of this Example 3 is
Angle of view of entire system 60.00 ° × 360 °
Rear group angle of view 13.52 °-52.56 °
Rear group entrance pupil diameter φ1.00mm
Image size φ2.44mm to φ7.95mm
It is.

実施例４の光学系１の中心軸２に沿ってとった断面図を図９に示す。また、この実施例の光学系全体の横収差図を図１０に示す。 A sectional view taken along the central axis 2 of the optical system 1 of Example 4 is shown in FIG. Further, FIG. 10 shows a lateral aberration diagram of the entire optical system of this example.

本実施例は、光学系１の中心軸２に同心に回転対称な屈折率が１より大きい後群透明媒体Ｌｂの透過面及び反射面を、光路内で一部共通に使用する球面で構成し、該後群透明媒体Ｌｂの前に前群透明媒体Ｌｆを配置した例である。 In this embodiment, the transmission surface and the reflection surface of the rear group transparent medium Lb having a refractive index larger than 1 concentrically symmetric with respect to the central axis 2 of the optical system 1 are configured as spherical surfaces that are partially shared in the optical path. This is an example in which the front group transparent medium Lf is disposed in front of the rear group transparent medium Lb.

前群Ｇｆは、中心軸２の周りで回転対称な屈折率が１より大きい前群透明媒体Ｌｆからなる。前群透明媒体Ｌｆは、中心軸１の周りで回転対称な屈折率が１より大きい樹脂等からなり、遠方からの光束２が入射し拡張回転自由曲面からなる前群第１透過面１１と、前群第１透過面１１と中心軸１を挟んで反対側で前群第１透過面１１より像面５と反対側に配置されていて、前群第１透過面１１から入射した光束が入射し拡張回転自由曲面からなる前群第１反射面１２と、前群第１反射面１２と中心軸１を挟んで反対側で前群第１反射面１２より像面５と反対側に配置され、前群第１反射面１２で反射された光束が入射し拡張回転自由曲面からなる前群第２反射面１３と、後群Ｇｂに面していて前群第２反射面１
２と中心軸２上で前群第２反射面１３より像面５側に配置され、前群第２反射面１３で反射された光束が入射し非球面からなる前群第２透過面１４とからなる。 The front group Gf is composed of a front group transparent medium Lf having a refractive index that is rotationally symmetric about the central axis 2 and greater than 1. The front group transparent medium Lf is made of a resin or the like having a rotationally symmetric refractive index greater than 1 around the central axis 1, and a front group first transmission surface 11 made of an extended rotation free-form surface with the incident light beam 2 from a distance. The light beam incident from the front group first transmission surface 11 is incident on the opposite side of the front group first transmission surface 11 from the front group first transmission surface 11 on the opposite side of the central axis 1 from the front group first transmission surface 11. The front group first reflecting surface 12 formed of an extended rotation free-form surface, and disposed on the opposite side of the front group first reflecting surface 12 and the image surface 5 on the opposite side of the front group first reflecting surface 12 with respect to the central axis 1. The front group second reflecting surface 13 which faces the rear group Gb and the front group second reflecting surface 13 which is formed of an extended rotation free curved surface upon incidence of the light beam reflected by the front group first reflecting surface 12.
2 and the central axis 2 on the image plane 5 side from the front group second reflecting surface 13, and the front group second transmitting surface 14 made of an aspherical surface by the incident light beam reflected by the front group second reflecting surface 13; Consists of.

光学系１は、光路Ａを形成する。光路Ａにおいて、光学系１の物体面３から入射する光束は、前群第１透過面１１を経て前群透明媒体Ｌｆ内に入り、中心軸２を横切って前群第１透過面１１と反対側の前群第１反射面１２で後群Ｇｂから離れるように像面５と反対側に反射され、前群第１反射面１２と中心軸２に対して反対側で後群Ｇｂから離れた側に位置している前群第２反射面１３で像面５側に反射され、射出面の前群第２透過面１４を経て前群透明媒体Ｌｆから外に出る。 The optical system 1 forms an optical path A. In the optical path A, the light beam incident from the object plane 3 of the optical system 1 enters the front group transparent medium Lf via the front group first transmission surface 11, crosses the central axis 2, and is opposite to the front group first transmission surface 11. Reflected on the opposite side to the image plane 5 so as to be separated from the rear group Gb by the front front group first reflecting surface 12, and separated from the rear group Gb on the side opposite to the front group first reflecting surface 12 and the central axis 2. It is reflected to the image surface 5 side by the front group second reflecting surface 13 located on the side, and exits from the front group transparent medium Lf through the front group second transmitting surface 14 of the exit surface.

その後、前群透明媒体Ｌｆと後１群透明媒体Ｌｂの間で中心軸２に同軸に配置された開口Ｓとを経て、後１群透明媒体Ｌｂ内に入る。後１群透明媒体Ｌｂでは、後１群第１透過面２１を経て入り、後１群第１反射面２２で一部が反射コーティング４ａ、一部が全反射により像面５と反対側に反射され、後１群第２反射面２３で反射コーティング４ｂにより像面５側に反射され、後１群第２透過面２４を経て後１群透明媒体Ｌｂから外に出る略Ｚ字状の光路を有する。その後、像面５の中心軸２から外れた半径方向の所定位置に円環状に結像する。 Thereafter, the light enters the rear first group transparent medium Lb through the opening S disposed coaxially with the central axis 2 between the front group transparent medium Lf and the rear first group transparent medium Lb. In the rear first group transparent medium Lb, it enters through the rear first group first transmission surface 21, and a part of the rear first group first reflection surface 22 is reflected on the reflective coating 4 a, and a part is reflected to the opposite side to the image surface 5 by total reflection. A substantially Z-shaped optical path is reflected from the rear first group second reflecting surface 23 to the image surface 5 side by the reflective coating 4b and exits from the rear first group second transparent medium Lb via the rear first group second transmitting surface 24. Have. Thereafter, an image is formed in an annular shape at a predetermined position in the radial direction deviating from the central axis 2 of the image plane 5.

この実施例４の仕様は、
全系の画角 60.00°×360°
後群の画角 26.47°〜55.67°
後群の入射瞳径 φ1.00mm
像の大きさ φ4.12mm〜φ7.66mm
である。 The specification of this Example 4 is
Angle of view of entire system 60.00 ° × 360 °
Rear group angle of view 26.47 °-55.67 °
Rear group entrance pupil diameter φ1.00mm
Image size φ4.12mm to φ7.66mm
It is.

実施例５の光学系１の中心軸２に沿ってとった断面図を図１１に示す。また、この実施例の光学系全体の横収差図を図１２に示す。 A sectional view taken along the central axis 2 of the optical system 1 of Example 5 is shown in FIG. Further, FIG. 12 shows a lateral aberration diagram of the entire optical system of this example.

本実施例は、光学系１の中心軸２に同心に回転対称な屈折率が１より大きい後群透明媒体Ｌｂの透過面及び反射面を、光路内で一部共通に使用する球面で構成し、該後群透明媒体Ｌｂの前に前群反射体Ｒｆを配置した例である。 In this embodiment, the transmission surface and the reflection surface of the rear group transparent medium Lb having a refractive index larger than 1 concentrically symmetric with respect to the central axis 2 of the optical system 1 are configured as spherical surfaces that are partially shared in the optical path. This is an example in which a front group reflector Rf is disposed in front of the rear group transparent medium Lb.

光学系１は、前群Ｇｆと、後群Ｇｂと、前群Ｇｆと後群Ｇｂの間で中心軸２に同軸に配置された開口Ｓとからなる。
前群Ｇｆは、中心軸２の周りで回転対称な前群反射体Ｒｆからなる。前群反射体Ｒｆは、像面５側に凸の前群第１反射面１２からなる。 The optical system 1 includes a front group Gf, a rear group Gb, and an opening S disposed coaxially with the central axis 2 between the front group Gf and the rear group Gb.
The front group Gf includes a front group reflector Rf that is rotationally symmetric about the central axis 2. The front group reflector Rf includes a front group first reflecting surface 12 that is convex toward the image plane 5 side.

後１群Ｇｂ１は、中心軸２の周りで回転対称な屈折率が１より大きい後１群透明媒体Ｌｂからなる。後１群透明媒体Ｌｂは、中心軸２上で球面からなる後１群第１透過面２１と、後１群第１透過面２１に対して像側に形成され、一部を反射コーティング４ａし、負の
パワーをもつ像面側に凹面を向けた後１群第１反射面２２と、後１群第１反射面２２に対して像面５と反対側に配置され、反射コーティング４ｂし、正のパワーをもつ像面側に凹面を向けた後１群第２反射面２３と、後１群第２反射面２３より像面５側に配置され、負のパワーをもつ後１群第２透過面２４とを有する。後１群第１透過面２１と後１群第２反射面２３は、同一位置同一形状からなり、後１群第１反射面２２と後１群第２透過面２４は、同一位置同一形状からなる。 The rear first group Gb1 is composed of a rear first group transparent medium Lb whose refractive index rotationally symmetric about the central axis 2 is greater than one. The rear first group transparent medium Lb is formed on the image side with respect to the rear first group first transmission surface 21 and the rear first group first transmission surface 21 formed of a spherical surface on the central axis 2, and a part of the rear first group transparent medium Lb has a reflective coating 4 a. A rear first group first reflecting surface 22 having a concave surface directed to the image surface side having a negative power, and disposed on the opposite side of the rear first group first reflecting surface 22 from the image surface 5, and a reflective coating 4b. The rear first group second reflecting surface 23 with the concave surface facing the image surface side having positive power, and the rear first group second reflecting surface 23 arranged on the image surface 5 side from the rear first group second reflecting surface 23 and having negative power. And a transmission surface 24. The rear first group first transmission surface 21 and the rear first group second reflection surface 23 have the same shape at the same position, and the rear first group first reflection surface 22 and the rear first group second transmission surface 24 have the same shape at the same position. Become.

光学系１は、光路Ａを形成する。光路Ａにおいて、光学系１の物体面３から入射する光束は、前群反射体Ｒｆの前群第１反射面１１と、前群反射体Ｒｆと後１群透明媒体Ｌｂの間で中心軸２に同軸に配置された開口Ｓとを経て、後１群透明媒体Ｌｂ内に入る。その後、前群透明媒体Ｌｆと後１群透明媒体Ｌｂの間に中心軸２に同軸に配置された開口Ｓとを経て、後１群透明媒体Ｌｂ内に入る。後１群透明媒体Ｌｂでは、後１群第１透過面２１を経て入り、後１群第１反射面２２で一部が反射コーティング４ａ、一部が全反射により像面５と反対側に反射され、後１群第２反射面２３で反射コーティング４ｂにより像面５側に反射され、後１群第２透過面２４を経て後１群透明媒体Ｌｂから外に出る略Ｚ字状の光路を有する。その後、像面５の中心軸２から外れた半径方向の所定位置に円環状に結像する。 The optical system 1 forms an optical path A. In the optical path A, the light beam incident from the object plane 3 of the optical system 1 is centered on the front group first reflecting surface 11 of the front group reflector Rf and between the front group reflector Rf and the rear group 1 transparent medium Lb. And enters the rear first group transparent medium Lb through an opening S arranged coaxially therewith. Thereafter, the light enters the rear first group transparent medium Lb through the opening S disposed coaxially with the central axis 2 between the front group transparent medium Lf and the rear first group transparent medium Lb. In the rear first group transparent medium Lb, it enters through the rear first group first transmission surface 21, and a part of the rear first group first reflection surface 22 is reflected on the reflective coating 4 a, and a part is reflected to the opposite side to the image surface 5 by total reflection. A substantially Z-shaped optical path is reflected from the rear first group second reflecting surface 23 to the image surface 5 side by the reflective coating 4b and exits from the rear first group second transparent medium Lb via the rear first group second transmitting surface 24. Have. Thereafter, an image is formed in an annular shape at a predetermined position in the radial direction deviating from the central axis 2 of the image plane 5.

この実施例５の仕様は、
全系の画角 60.00°(10±30°)×360°
後群の画角 29.59°〜49.38°
後群の入射瞳径 φ1.00mm
像の大きさ φ2.56mm〜φ3.92mm
である。 The specification of this Example 5 is
Angle of view of the entire system 60.00 ° (10 ± 30 °) x 360 °
Rear group angle of view 29.59 °-49.38 °
Rear group entrance pupil diameter φ1.00mm
Image size φ2.56mm to φ3.92mm
It is.

また、最大像高をＩmax（mm）、最小像高をＩmin（mm）、後群Ｇｒの最大画角をθmax
（度）、後群Ｇｒの最小画角をθmin（度）、焦点距離Ｆ＝（Ｉmax-Ｉmin）／（θmax−
θmin）とし、後群Ｇｒの外径をＤ（mm）、平行平面の保護ガラスを除いた後群Ｇｒの全
長をＬｓ（mm）、後群第１反射面２２の曲率をＲ１、後群第２反射面２３の曲率をＲ２とするとき、
実施例１実施例２実施例３実施例４実施例５
I max 3.92 3.96 3.98 3.83 1.96
θmax 60.22 58.29 52.56 55.67 49.38
I min 2.02 1.78 1.22 2.06 1.28
θmin 26.81 22.92 13.52 26.47 29.59
Ｆ 0.057 0.061 0.071 0.061 0.034
Ｄ 24.80 21.60 25.20 20.40 12.00
Ｌ 9.600 7.800 13.000 6.20 4.20
Ｄ（２×Ｉmax） 3.167 2.730 3.169 2.663 3.069
Ｌ（２×Ｉmax） 1.226 0.986 1.635 0.809 1.074
Ｒ１ 6.92 7.33 8.06 9.35 3.32
Ｒ２ 8.10 8.15 8.95 8.89 4.13
Ｒ１／Ｒ２ 0.85 0.90 0.90 1.05 0.81
である。 The maximum image height is Imax (mm), the minimum image height is Imin (mm), and the maximum field angle of the rear group Gr is θmax.
(Degrees), the minimum angle of view of the rear group Gr is θmin (degrees), and the focal length F = (Imax−Imin) / (θmax−
θmin), the outer diameter of the rear group Gr is D (mm), the total length of the rear group Gr excluding the parallel-plane protective glass is Ls (mm), the curvature of the rear group first reflecting surface 22 is R1, and the rear group number 2 When the curvature of the reflecting surface 23 is R2,
Example 1 Example 2 Example 3 Example 4 Example 5
I max 3.92 3.96 3.98 3.83 1.96
θmax 60.22 58.29 52.56 55.67 49.38
I min 2.02 1.78 1.22 2.06 1.28
θmin 26.81 22.92 13.52 26.47 29.59
F 0.057 0.061 0.071 0.061 0.034
D 24.80 21.60 25.20 20.40 12.00
L 9.600 7.800 13.000 6.20 4.20
D (2 x Imax) 3.167 2.730 3.169 2.663 3.069
L (2 x Imax) 1.226 0.986 1.635 0.809 1.074
R1 6.92 7.33 8.06 9.35 3.32
R2 8.10 8.15 8.95 8.89 4.13
R1 / R2 0.85 0.90 0.90 1.05 0.81
It is.

以下に、上記実施例１〜５の構成パラメータを示す。なお、以下の表中の “ＲＥ”は
反射面を示す。 The configuration parameters of Examples 1 to 5 are shown below. In the table below, “RE” indicates a reflecting 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 ∞ ∞ 偏心(1)
1 ＥＲＦＳ[1] 0.00 偏心(2) 1.8348 42.7
2（ＲＥ）ＥＲＦＳ[2] 0.00 偏心(3) 1.8348 42.7
3（ＲＥ）ＥＲＦＳ[3] 0.00 偏心(4) 1.8348 42.7
4 81.36 0.00 偏心(5)
5 ∞（絞り） 0.00
6 8.10 3.48 1.8348 42.7
7（ＲＥ） 6.92 -3.48 1.8348 42.7
8（ＲＥ） 8.10 3.48 1.8348 42.7
9 6.92 4.23
10 ∞ 1.00 1.5163 64.1
11 ∞ 0.70
像面 ∞
ＥＲＦＳ[1]
ＲＹ 27.36
θ 53.19
Ｒ -10.91
ＥＲＦＳ[2]
ＲＹ -23.52
θ 37.63
Ｒ 7.93
Ｃ4 2.4445E-05
ＥＲＦＳ[3]
ＲＹ -56.42
θ -5.65
Ｒ 6.05
Ｃ4 8.0159E-05
偏心[1]
Ｘ 0.00 Ｙ 0.00 Ｚ -9.64
α 75.00 β 0.00 γ 0.00
偏心[2]
Ｘ 0.00 Ｙ 0.00 Ｚ -12.56
α 0.00 β 0.00 γ 0.00
偏心[3]
Ｘ 0.00 Ｙ 0.00 Ｚ -3.71
α 0.00 β 0.00 γ 0.00
偏心[4]
Ｘ 0.00 Ｙ 0.00 Ｚ -13.93
α 0.00 β 0.00 γ 0.00
偏心[5]
Ｘ 0.00 Ｙ 0.00 Ｚ -1.00
α 0.00 β 0.00 γ 0.00 Example 1
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞ Eccentricity (1)
1 ERFS [1] 0.00 Eccentricity (2) 1.8348 42.7
2 (RE) ERFS [2] 0.00 Eccentricity (3) 1.8348 42.7
3 (RE) ERFS [3] 0.00 Eccentricity (4) 1.8348 42.7
4 81.36 0.00 Eccentricity (5)
5 ∞ (Aperture) 0.00
6 8.10 3.48 1.8348 42.7
7 (RE) 6.92 -3.48 1.8348 42.7
8 (RE) 8.10 3.48 1.8348 42.7
9 6.92 4.23
10 ∞ 1.00 1.5163 64.1
11 ∞ 0.70
Image plane ∞
ERFS [1]
RY 27.36
θ 53.19
R -10.91
ERFS [2]
RY -23.52
θ 37.63
R 7.93
C4 2.4445E-05
ERFS [3]
RY -56.42
θ -5.65
R 6.05
C4 8.0159E-05
Eccentric [1]
X 0.00 Y 0.00 Z -9.64
α 75.00 β 0.00 γ 0.00
Eccentric [2]
X 0.00 Y 0.00 Z -12.56
α 0.00 β 0.00 γ 0.00
Eccentric [3]
X 0.00 Y 0.00 Z -3.71
α 0.00 β 0.00 γ 0.00
Eccentric [4]
X 0.00 Y 0.00 Z -13.93
α 0.00 β 0.00 γ 0.00
Eccentric [5]
X 0.00 Y 0.00 Z -1.00
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 ∞ ∞ 偏心(1)
1 ＥＲＦＳ[1] 0.00 偏心(2) 1.8348 42.7
2（ＲＥ）ＥＲＦＳ[2] 0.00 偏心(3) 1.8348 42.7
3（ＲＥ）ＥＲＦＳ[3] 0.00 偏心(4) 1.8348 42.7
4 -6.46 0.00 偏心(5)
5 ∞（絞り） 0.00
6 8.15 3.33 1.8348 42.7
7（ＲＥ） 7.33 -3.33 1.8348 42.7
8（ＲＥ） 8.15 3.33 1.8348 42.7
9 7.33 2.66
10 ∞ 1.00 1.5163 64.1
11 ∞ 0.70
像面 ∞
ＥＲＦＳ[1]
ＲＹ -5.96
θ 72.36
Ｒ -9.56
ＥＲＦＳ[2]
ＲＹ -16.71
θ 50.86
Ｒ 7.55
Ｃ4 -2.4173E-04
ＥＲＦＳ[3]
ＲＹ 8.79
θ 31.80
Ｒ -6.39
Ｃ4 1.9000E-03
偏心[1]
Ｘ 0.00 Ｙ 0.00 Ｚ -5.79
α 42.56 β 0.00 γ 0.00
偏心[2]
Ｘ 0.00 Ｙ 0.00 Ｚ -16.21
α 0.00 β 0.00 γ 0.00
偏心[3]
Ｘ 0.00 Ｙ 0.00 Ｚ -4.96
α 0.00 β 0.00 γ 0.00
偏心[4]
Ｘ 0.00 Ｙ 0.00 Ｚ -18.89
α 0.00 β 0.00 γ 0.00
偏心[5]
Ｘ 0.00 Ｙ 0.00 Ｚ -0.10
α 0.00 β 0.00 γ 0.00 Example 2
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞ Eccentricity (1)
1 ERFS [1] 0.00 Eccentricity (2) 1.8348 42.7
2 (RE) ERFS [2] 0.00 Eccentricity (3) 1.8348 42.7
3 (RE) ERFS [3] 0.00 Eccentricity (4) 1.8348 42.7
4 -6.46 0.00 Eccentricity (5)
5 ∞ (Aperture) 0.00
6 8.15 3.33 1.8348 42.7
7 (RE) 7.33 -3.33 1.8348 42.7
8 (RE) 8.15 3.33 1.8348 42.7
9 7.33 2.66
10 ∞ 1.00 1.5163 64.1
11 ∞ 0.70
Image plane ∞
ERFS [1]
RY -5.96
θ 72.36
R -9.56
ERFS [2]
RY -16.71
θ 50.86
R 7.55
C4 -2.4173E-04
ERFS [3]
RY 8.79
θ 31.80
R -6.39
C4 1.9000E-03
Eccentric [1]
X 0.00 Y 0.00 Z -5.79
α 42.56 β 0.00 γ 0.00
Eccentric [2]
X 0.00 Y 0.00 Z -16.21
α 0.00 β 0.00 γ 0.00
Eccentric [3]
X 0.00 Y 0.00 Z -4.96
α 0.00 β 0.00 γ 0.00
Eccentric [4]
X 0.00 Y 0.00 Z -18.89
α 0.00 β 0.00 γ 0.00
Eccentric [5]
X 0.00 Y 0.00 Z -0.10
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 ∞ ∞ 偏心(1)
1 ＥＲＦＳ[1] 0.00 偏心(2)
2（ＲＥ）ＥＲＦＳ[2] 0.00 偏心(3) 1.8348 42.7
3 -16.07 0.00 偏心(4)
4 ∞（絞り） 0.10
7 8.95 3.62 1.8348 42.7
8（ＲＥ） 8.06 -3.62 1.8348 42.7
9（ＲＥ） 8.95 3.62 1.8348 42.7
10 8.06 9.31
像面 ∞
ＥＲＦＳ[1]
ＲＹ -2685.93
θ -34.51
Ｒ -6.91
ＥＲＦＳ[2]
ＲＹ 14.47
θ -45.37
Ｒ 5.36
Ｃ4 -4.6617E-05
偏心[1]
Ｘ 0.00 Ｙ 0.00 Ｚ -7.24
α -90.00 β 0.00 γ 0.00
偏心[2]
Ｘ 0.00 Ｙ 0.00 Ｚ -7.24
α 0.00 β 0.00 γ 0.00
偏心[3]
Ｘ 0.00 Ｙ 0.00 Ｚ -12.35
α 0.00 β 0.00 γ 0.00
偏心[4]
Ｘ 0.00 Ｙ 0.00 Ｚ -0.10
α 0.00 β 0.00 γ 0.00 Example 3
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞ Eccentricity (1)
1 ERFS [1] 0.00 Eccentricity (2)
2 (RE) ERFS [2] 0.00 Eccentricity (3) 1.8348 42.7
3 -16.07 0.00 Eccentricity (4)
4 ∞ (Aperture) 0.10
7 8.95 3.62 1.8348 42.7
8 (RE) 8.06 -3.62 1.8348 42.7
9 (RE) 8.95 3.62 1.8348 42.7
10 8.06 9.31
Image plane ∞
ERFS [1]
RY -2685.93
θ -34.51
R -6.91
ERFS [2]
RY 14.47
θ -45.37
R 5.36
C4 -4.6617E-05
Eccentric [1]
X 0.00 Y 0.00 Z -7.24
α -90.00 β 0.00 γ 0.00
Eccentric [2]
X 0.00 Y 0.00 Z -7.24
α 0.00 β 0.00 γ 0.00
Eccentric [3]
X 0.00 Y 0.00 Z -12.35
α 0.00 β 0.00 γ 0.00
Eccentric [4]
X 0.00 Y 0.00 Z -0.10
α 0.00 β 0.00 γ 0.00

実施例４
面番号曲率半径面間隔偏心屈折率アッベ数
物体面 ∞ ∞ 偏心(1)
1 ＥＲＦＳ[1] 0.00 偏心(2) 2.0033 28.3
2（ＲＥ）ＥＲＦＳ[2] 0.00 偏心(3) 2.0033 28.3
3（ＲＥ）ＥＲＦＳ[3] 0.00 偏心(4) 2.0033 28.3
4 ＡＳＳ[1] 0.00 偏心(5)
5 ∞（絞り） 0.10
6 8.89 3.34 1.8348 42.7
7（ＲＥ） 9.35 -3.34 1.8348 42.7
8（ＲＥ） 8.89 3.34 1.8348 42.7
9 9.35 4.76
像面 ∞
ＥＲＦＳ[1]
ＲＹ 21.56
θ 88.06
Ｒ -7.74
ＥＲＦＳ[2]
ＲＹ -13.48
θ 87.67
Ｒ 8.55
Ｃ4 -1.5105E-04
ＥＲＦＳ[3]
ＲＹ 10.49
θ 43.16
Ｒ -6.45
Ｃ4 6.0876E-04
ＡＳＳ[1]
Ｒ -12.90
k 0.0000
a 2.4853E-03
偏心[1]
Ｘ 0.00 Ｙ 0.00 Ｚ -14.91
α 132.30 β 0.00 γ 0.00
偏心[2]
Ｘ 0.00 Ｙ 0.00 Ｚ -6.96
α 0.00 β 0.00 γ 0.00
偏心[3]
Ｘ 0.00 Ｙ 0.00 Ｚ -12.37
α 0.00 β 0.00 γ 0.00
偏心[4]
Ｘ 0.00 Ｙ 0.00 Ｚ -18.62
α 0.00 β 0.00 γ 0.00
偏心[5]
Ｘ 0.00 Ｙ 0.00 Ｚ -0.10
α 0.00 β 0.00 γ 0.00 Example 4
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞ Eccentricity (1)
1 ERFS [1] 0.00 Eccentricity (2) 2.0033 28.3
2 (RE) ERFS [2] 0.00 Eccentricity (3) 2.0033 28.3
3 (RE) ERFS [3] 0.00 Eccentricity (4) 2.0033 28.3
4 ASS [1] 0.00 Eccentricity (5)
5 ∞ (Aperture) 0.10
6 8.89 3.34 1.8348 42.7
7 (RE) 9.35 -3.34 1.8348 42.7
8 (RE) 8.89 3.34 1.8348 42.7
9 9.35 4.76
Image plane ∞
ERFS [1]
RY 21.56
θ 88.06
R -7.74
ERFS [2]
RY -13.48
θ 87.67
R 8.55
C4 -1.5105E-04
ERFS [3]
RY 10.49
θ 43.16
R -6.45
C4 6.0876E-04
ASS [1]
R -12.90
k 0.0000
a 2.4853E-03
Eccentric [1]
X 0.00 Y 0.00 Z -14.91
α 132.30 β 0.00 γ 0.00
Eccentric [2]
X 0.00 Y 0.00 Z -6.96
α 0.00 β 0.00 γ 0.00
Eccentric [3]
X 0.00 Y 0.00 Z -12.37
α 0.00 β 0.00 γ 0.00
Eccentric [4]
X 0.00 Y 0.00 Z -18.62
α 0.00 β 0.00 γ 0.00
Eccentric [5]
X 0.00 Y 0.00 Z -0.10
α 0.00 β 0.00 γ 0.00

実施例５
面番号曲率半径面間隔偏心屈折率アッベ数
物体面 ∞ ∞
1（ＲＥ）-16.88 5.00
2 ∞（絞り） 0.10
3 4.13 1.74 1.8348 42.7
4（ＲＥ） 3.32 -1.74 1.8348 42.7
5（ＲＥ） 4.13 1.74 1.8348 42.7
6 3.32 2.52
像面 ∞ Example 5
Surface number Curvature radius Surface spacing Eccentricity Refractive index Abbe number Object surface ∞ ∞
1 (RE) -16.88 5.00
2 ∞ (Aperture) 0.10
3 4.13 1.74 1.8348 42.7
4 (RE) 3.32 -1.74 1.8348 42.7
5 (RE) 4.13 1.74 1.8348 42.7
6 3.32 2.52
Image plane ∞

図１３は、本実施例の画像と撮像素子の配置例を示す。図１３（ａ）は、画面比が１６：９の撮像素子を使用した例である。上下方向の画像は使用しない場合、光路Ａの画像Ａ１の左右の位置に撮像素子５０の大きさを合致させると好ましい。図１３（ｂ）は、画面比が４：３の撮像素子５０を使用し、上下方向の映像は使用しない場合を示す。図１３（ｃ）は、画面比が４：３の撮像素子５０を使用し、光路Ａでの画像Ａ１に撮像素子５０の大きさを合致させた例である。このように、配置をすると、光路Ａの画像Ａ１をすべて撮像することができる。
以下に、本発明の光学系１の適用例として、撮影光学系１０１又は投影光学系１０２の使用例を説明する。図１４は、内視鏡先端の撮影光学系として本発明による撮影光学系１０１を用いた例を示すための図であり、図１４（ａ）は、硬性内視鏡１１０の先端１０１に本発明による撮影光学系を取り付けて画像を撮像観察する例である。図１４（ｂ）にその先端の概略の構成を示す。本発明によるパノラマ撮影光学系１０１の入射面１１の周囲には円周方向に伸びる開口１０６を有するケーシング等からなるフレア絞り１０７が配置され、フレア光が入射するのを防止している。また、図１４（ｃ）は、軟性電子内視鏡１１３の先端に本発明によるパノラマ撮影光学系１０１を同様に取り付けて、表示装置１１４に撮影された画像を、画像処理を施して歪みを補正して表示するようにした例である。 FIG. 13 shows an arrangement example of the image and the image sensor of the present embodiment. FIG. 13A shows an example in which an image sensor with a screen ratio of 16: 9 is used. When an image in the vertical direction is not used, it is preferable to match the size of the image sensor 50 with the left and right positions of the image A1 in the optical path A. FIG. 13B shows a case where the image sensor 50 having a screen ratio of 4: 3 is used, and an image in the vertical direction is not used. FIG. 13C illustrates an example in which the image sensor 50 having a screen ratio of 4: 3 is used, and the size of the image sensor 50 is matched with the image A1 in the optical path A. Thus, when arranged, all the images A1 of the optical path A can be taken.
Hereinafter, as an application example of the optical system 1 of the present invention, a usage example of the photographing optical system 101 or the projection optical system 102 will be described. FIG. 14 is a diagram for illustrating an example in which the photographing optical system 101 according to the present invention is used as a photographing optical system at the distal end of an endoscope. FIG. 14A illustrates the present invention at the distal end 101 of the rigid endoscope 110. This is an example in which an imaging optical system is attached and an image is taken and observed. FIG. 14B shows a schematic configuration of the tip. A flare stop 107 made of a casing or the like having an opening 106 extending in the circumferential direction is disposed around the incident surface 11 of the panoramic photographing optical system 101 according to the present invention to prevent the flare light from entering. FIG. 14C shows a panoramic imaging optical system 101 according to the present invention attached to the tip of the flexible electronic endoscope 113 in the same manner, and the image captured on the display device 114 is subjected to image processing to correct distortion. This is an example of displaying.

図１５は、カプセル内視鏡１２０に本発明による撮影光学系１０１を取り付けて３６０°全方位の画像を撮像観察する例である。本発明による撮影光学系１０１の光路Ａにおける前群Ｇｆの第１透過面１１の周囲には円周方向に伸びる開口１０６を有するケーシング
等に、フレア絞り１０７が形成され、フレア光が入射するのを防止している。 FIG. 15 shows an example in which the photographing optical system 101 according to the present invention is attached to the capsule endoscope 120 and images of 360 ° omnidirectional images are taken and observed. A flare stop 107 is formed in a casing having an opening 106 extending in the circumferential direction around the first transmission surface 11 of the front group Gf in the optical path A of the photographing optical system 101 according to the present invention, and flare light is incident thereon. Is preventing.

図１３及び図１４に示すように、内視鏡に撮影光学系１０１を用いることにより、撮影光学系１０１の後方の画像を撮像観察することができ、従来と異なる角度から様々な部位を撮像観察することができる。 As shown in FIGS. 13 and 14, by using the imaging optical system 101 for the endoscope, it is possible to image and observe images behind the imaging optical system 101, and to image and observe various parts from angles different from the conventional ones. can do.

図１６（ａ）は、自動車１３０の前方に撮影光学系として本発明による撮影光学系１０１を取り付けて、車内の表示装置に各撮影光学系１０１を経て撮影された画像を、画像処理を施して歪みを補正して同時に表示するようにした例を示す図であり、図１６（ｂ）は、自動車１３０の各コーナやヘッド部のポールの頂部に撮影光学系として本発明による撮影光学系１０１を複数取り付けて、車内の表示装置に各撮影光学系１０１を経て撮影された画像を、画像処理を施して歪みを補正して同時に表示するようにした例を示す図である。この場合、図１５（ａ）に示したように、光路Ａの画像Ａ１の左右の位置に撮像素子５０の大きさを合致させると、左右の画像が広く撮像でき、好ましい。 In FIG. 16A, a photographing optical system 101 according to the present invention is attached as a photographing optical system in front of an automobile 130, and an image photographed through each photographing optical system 101 is subjected to image processing on a display device in a vehicle. FIG. 16B is a diagram showing an example in which distortion is corrected and simultaneously displayed, and FIG. 16B shows a photographing optical system 101 according to the present invention as a photographing optical system at each corner of the automobile 130 and the top of the pole of the head portion. It is a figure which shows the example which attached the plurality and displayed the image image | photographed through each imaging | photography optical system 101 on the display apparatus in a vehicle, performing image processing and correct | amending distortion simultaneously. In this case, as shown in FIG. 15A, it is preferable to match the size of the image sensor 50 to the left and right positions of the image A1 in the optical path A, because the left and right images can be captured widely.

また、図１７は、投影装置１４０の投影光学系として本発明による投影光学系１０２を用い、その像面５に配置した表示素子にパノラマ画像を表示し、投影光学系１０２を通して３６０°全方位に配置したスクリーン１４１に３６０°全方位画像を投影表示する例である。 17 uses the projection optical system 102 according to the present invention as the projection optical system of the projection apparatus 140, displays a panoramic image on a display element arranged on the image plane 5, and displays 360 ° in all directions through the projection optical system 102. This is an example in which a 360 ° omnidirectional image is projected and displayed on the arranged screen 141.

さらに、図１８は、建物１５０の外部に本発明による撮影光学系１０１を用いた撮影装置１５１を取り付け、屋内に本発明による撮影光学系１０１を用いた投影装置１５１を配置し、撮影装置１５１で撮像された映像を電線１５２を介して投影装置１４０に送るように接続している。このような配置において、屋外の３６０°全方位の被写体Ｐを、撮影光学系１０１を経て撮影装置１５１で撮影し、その映像信号を電線１５２を介して投影装置１４０に送り、像面に配置した表示素子にその映像を表示して、投影光学系１０２を通して屋内の壁面等に被写体Ｐの映像Ｐ'を投影表示するようにしている例である。 Further, FIG. 18 shows that the photographing apparatus 151 using the photographing optical system 101 according to the present invention is attached to the outside of the building 150, and the projection apparatus 151 using the photographing optical system 101 according to the present invention is disposed indoors. It connects so that the imaged image may be sent to the projection device 140 via the electric wire 152. In such an arrangement, an outdoor 360 ° omnidirectional subject P is photographed by the photographing device 151 via the photographing optical system 101, and the video signal is sent to the projection device 140 via the electric wire 152 and disposed on the image plane. In this example, the image is displayed on the display element, and the image P ′ of the subject P is projected and displayed on an indoor wall surface or the like through the projection optical system 102.

本発明の光学系の座標系を説明するための図である。It is a figure for demonstrating the coordinate system of the optical system of this invention. 拡張回転自由曲面の原理を示す図である。It is a figure which shows the principle of an extended rotation free-form surface. 本発明の実施例１の光学系の中心軸に沿ってとった断面図である。It is sectional drawing taken along the central axis of the optical system of Example 1 of this invention. 実施例１の光学系全体の横収差図を示す図である。2 is a transverse aberration diagram for the whole optical system of Example 1. FIG. 本発明の実施例２の光学系の中心軸に沿ってとった断面図である。It is sectional drawing taken along the central axis of the optical system of Example 2 of this invention. 実施例２の光学系全体の横収差図を示す図である。6 is a lateral aberration diagram for the whole optical system of Example 2. FIG. 本発明の実施例３の光学系の中心軸に沿ってとった断面図である。It is sectional drawing taken along the central axis of the optical system of Example 3 of this invention. 実施例３の光学系全体の横収差図を示す図である。FIG. 6 is a transverse aberration diagram for the whole optical system of Example 3. 本発明の実施例４の光学系の中心軸に沿ってとった断面図である。It is sectional drawing taken along the central axis of the optical system of Example 4 of this invention. 実施例４の光学系全体の横収差図を示す図である。FIG. 6 is a transverse aberration diagram for the whole optical system of Example 4. 本発明の実施例５の光学系の中心軸に沿ってとった断面図である。It is sectional drawing taken along the central axis of the optical system of Example 5 of this invention. 実施例５の光学系全体の横収差図を示す図である。FIG. 6 is a lateral aberration diagram for the whole optical system of Example 5. 本発明の光学系の画像と撮像素子の配置例を示す図である。It is a figure which shows the example of arrangement | positioning of the image of the optical system of this invention, and an image pick-up element. 本発明の光学系を内視鏡先端の撮影光学系として用いた例を示す図である。It is a figure which shows the example which used the optical system of this invention as an imaging | photography optical system of the endoscope front-end | tip. 本発明の光学系をカプセル内視鏡の撮影光学系として用いた例を示す図である。It is a figure which shows the example which used the optical system of this invention as the imaging | photography optical system of a capsule endoscope. 本発明の光学系を自動車の撮影光学系として用いた例を示す図である。It is a figure which shows the example which used the optical system of this invention as the imaging | photography optical system of a motor vehicle. 本発明の光学系を投影装置の投影光学系として用いた例を示す図である。It is a figure which shows the example which used the optical system of this invention as a projection optical system of a projection apparatus. 本発明の光学系を屋外の被写体を撮影する撮影光学系として用いた例を示す図である。It is a figure which shows the example which used the optical system of this invention as an imaging | photography optical system which image | photographs a to-be-photographed object.

符号の説明Explanation of symbols

１…光学系
２…中心軸
３…物体面（無限遠なので図示しない）
５…像面 DESCRIPTION OF SYMBOLS 1 ... Optical system 2 ... Center axis 3 ... Object surface (It is not illustrated because it is infinite)
5. Image plane

Claims

少なくとも１つの反射面を含む前群と、後群と、前記前群と前記後群の間に配置された開口とを有し、中心軸を含む断面内で、前記中心軸の周りで回転対称な光学系において、前記後群は、前記開口の像面側に配置され、屈折率が１より大きい後群透明媒体を有し、前記後群透明媒体は、前記開口近傍の前記中心軸上に配置された後群第１透過面と、前記後群第１透過面より像面側に配置され、像面側に凹面を向けた後群第１反射面と、前記後群第１反射面より像面と反対側に配置され、像面側に凹面を向けた後群第２反射面と、前記後群第２反射面より像面側に配置された後群第２透過面と、を有し、前記後群第１反射面と前記後群第２反射面のうち少なくとも１面は、中心軸上で連続な曲面で構成されており、前記後群透明媒体に入射する光束は、順光線追跡の順に、前記開口を通り、前記後群第１透過面を経て前記後群透明媒体内に入り、前記後群第１反射面で像面と反対側に反射され、前記後群第２反射面で像面側に反射され、前記後群第２透過面を経て前記後群透明媒体から像面側に外へ出る略Ｚ字状の第１光路を構成し、前記第１光路の少なくとも前記後群第１反射面と前記後群第２反射面の間は、前記中心軸に対して片側のみで構成され、前記第１光路中に中間像が結像されることなく、像面に円環状に結像されることを特徴とする光学系。 A front group including at least one reflecting surface, a rear group, and an opening disposed between the front group and the rear group, and rotationally symmetric about the central axis in a cross section including the central axis In this optical system, the rear group is disposed on the image plane side of the opening and has a rear group transparent medium having a refractive index greater than 1, and the rear group transparent medium is on the central axis in the vicinity of the opening. From the rear group first transmitting surface, the rear group first reflecting surface disposed on the image plane side from the rear group first transmitting surface, with the concave surface facing the image plane side, and the rear group first reflecting surface A rear group second reflecting surface that is disposed on the opposite side of the image surface and has a concave surface facing the image surface side; and a rear group second transmitting surface that is disposed on the image surface side from the rear group second reflecting surface. In addition, at least one of the rear group first reflecting surface and the rear group second reflecting surface is formed by a continuous curved surface on the central axis, and is incident on the rear group transparent medium. The luminous flux passes through the aperture in the order of forward ray tracing, enters the rear group transparent medium through the rear group first transmission surface, is reflected by the rear group first reflection surface on the side opposite to the image plane, and A substantially Z-shaped first optical path is reflected from the rear group second reflecting surface to the image plane side, and passes through the rear group second transmitting surface and exits from the rear group transparent medium to the image plane side. Between at least the rear group first reflecting surface and the rear group second reflecting surface in one optical path is configured only on one side with respect to the central axis, and an intermediate image is not formed in the first optical path. An optical system characterized in that an image is formed in an annular shape on the image plane.

前記後群の第１反射面は球面であることを特徴とする請求項１に記載の光学系。 The optical system according to claim 1, wherein the first reflecting surface of the rear group is a spherical surface.

前記後群第１反射面は、全反射作用と、反射コーティングにより反射するように構成され、前記反射コーティングは前記後群第１反射面の中心軸近傍のみに施されていることを特徴とする請求項１又は請求項２に記載の光学系。 The rear group first reflective surface is configured to reflect by a total reflection action and a reflective coating, and the reflective coating is provided only in the vicinity of the central axis of the rear group first reflective surface. The optical system according to claim 1 or 2.

前記後群第１透過面と前記後群第２反射面は、前記後群透明媒体の物体側に配置されていることを特徴とする請求項１乃至請求項３のいずれかに記載の光学系。 4. The optical system according to claim 1, wherein the rear group first transmitting surface and the rear group second reflecting surface are disposed on an object side of the rear group transparent medium. 5. .

前記後群第１透過面と前記後群第２反射面は、同一位置同一形状からなることを特徴とする請求項１乃至請求項４のいずれかに記載の光学系。 5. The optical system according to claim 1, wherein the rear group first transmission surface and the rear group second reflection surface have the same shape at the same position. 6.

前記後群第１反射面と前記後群第２透過面は、前記後群透明媒体の像面側に配置されていることを特徴とする請求項１乃至請求項５のいずれかに記載の光学系。 6. The optical system according to claim 1, wherein the rear group first reflecting surface and the rear group second transmitting surface are disposed on an image surface side of the rear group transparent medium. system.

前記後群第１反射面と前記後群第２透過面は、同一位置同一形状からなることを特徴とする請求項１乃至請求項６のいずれかに記載の光学系。 The optical system according to claim 1, wherein the rear group first reflecting surface and the rear group second transmitting surface have the same shape at the same position.

前記前群は、中心軸の周りで回転対称な屈折率が１より大きい前群透明媒体を有し、前記前群透明媒体は、前群第１透過面と、前記前群第１透過面より像面側に配置された前群第１反射面と、前記前群第１反射面より像面と反対側に配置された前群第２反射面と、前記前群第２反射面より像面側に配置された前群第２透過面と、を有し、前記前群透明媒体に入射する光束は、順光線追跡の順に、前記前群第１透過面を経て前記前群透明媒体内に入り、中心軸と交差した後、前記前群第１反射面で像面と反対側に反射され、中心軸と交差することなく、前記前群第２反射面で像面側に反射され、前記前群第２透過面を経て前記前群透明媒体から像面側に外へ出る光路を構成することを特徴とする請求項１乃至請求項７のいずれかに記載の光学系。 The front group includes a front group transparent medium having a refractive index that is rotationally symmetric about a central axis and having a refractive index greater than 1. The front group transparent medium includes a front group first transmission surface and a front group first transmission surface. A front group first reflecting surface disposed on the image surface side, a front group second reflecting surface disposed on the opposite side of the image surface from the front group first reflecting surface, and an image surface from the front group second reflecting surface A front group second transmission surface disposed on the side, and the light beam incident on the front group transparent medium passes through the front group first transmission surface and enters the front group transparent medium in the order of forward ray tracing. After entering and intersecting the central axis, the front group first reflecting surface is reflected to the opposite side to the image plane, and without intersecting the central axis, the front group second reflecting surface is reflected to the image plane side, 8. The optical system according to claim 1, wherein an optical path that exits outward from the front group transparent medium to the image plane side through a front group second transmission surface is formed. 9.

前記前群は、中心軸の周りで回転対称な屈折率が１より大きい前群透明媒体を有し、前記前群透明媒体は、前群第１透過面と、前記前群第１透過面より像面側に配置された前群第１反射面と、前記前群第１反射面より像面と反対側に配置された前群第２反射面と、前記前群第２反射面より像面側に配置された前群第２透過面と、を有し、前記前群透明媒体
に入射する光束は、順光線追跡の順に、前記前群第１透過面を経て前記前群透明媒体内に入り、中心軸と交差した後、前記前群第１反射面で像面と反対側に反射され、再度中心軸と交差した後、前記前群第２反射面で像面側に反射され、前記前群第２透過面を経て前記前群透明媒体から像面側に外へ出る光路を構成することを特徴とする請求項１乃至請求項７のいずれかに記載の光学系。 The front group includes a front group transparent medium having a refractive index that is rotationally symmetric about a central axis and having a refractive index greater than 1. The front group transparent medium includes a front group first transmission surface and a front group first transmission surface. A front group first reflecting surface disposed on the image surface side, a front group second reflecting surface disposed on the opposite side of the image surface from the front group first reflecting surface, and an image surface from the front group second reflecting surface A front group second transmission surface disposed on the side, and the light beam incident on the front group transparent medium passes through the front group first transmission surface and enters the front group transparent medium in the order of forward ray tracing. After entering and intersecting the central axis, the front group first reflecting surface is reflected to the opposite side of the image plane, and after intersecting the central axis again, the front group second reflecting surface is reflected to the image plane side, 8. The optical system according to claim 1, wherein an optical path that exits from the front group transparent medium to the image surface side through a front group second transmission surface is formed.

前記前群は、中心軸の周りで回転対称な屈折率が１より大きい前群透明媒体を有し、前記前群透明媒体は、前群第１透過面と、前記前群第１透過面より像面と反対側に配置された前群第１反射面と、前記前群第１反射面より像面側に配置された前群第２透過面と、を有し、前記前群透明媒体に入射する光束は、順光線追跡の順に、前記前群第１透過面を経て前記前群透明媒体内に入り、中心軸と交差した後、前記前群第１反射面で像面側に反射され、前記前群第２透過面を経て前記前群透明媒体から像面側に外へ出る光路を構成することを特徴とする請求項１乃至請求項７のいずれかに記載の光学系。 The front group includes a front group transparent medium having a refractive index that is rotationally symmetric about a central axis and having a refractive index greater than 1. The front group transparent medium includes a front group first transmission surface and a front group first transmission surface. A front group first reflecting surface disposed on the opposite side of the image surface; and a front group second transmitting surface disposed on the image surface side from the front group first reflecting surface; Incident light flux enters the front group transparent medium via the front group first transmission surface in the order of forward ray tracing, intersects the central axis, and is then reflected by the front group first reflection surface toward the image plane side. 8. The optical system according to claim 1, wherein an optical path that exits from the front group transparent medium to the image plane side through the front group second transmission surface is configured. 9.

最大像高をＩmax、前記後群の外径をＤとするとき、
０．５＜Ｄ／（２×Ｉmax）＜１０・・・（１）
なる条件を満足することを特徴とする請求項１乃至請求項１０のいずれかに記載の光学系。 When the maximum image height is Imax and the outer diameter of the rear group is D,
0.5 <D / (2 × Imax) <10 (1)
The optical system according to claim 1, wherein the following condition is satisfied.

最大像高をＩmax、前記開口から前記像面までの距離をＬとするとき、
０．５＜Ｌ／（２×Ｉmax）＜１０・・・（２）
なる条件を満足することを特徴とする請求項１乃至請求項１１のいずれかに記載の光学系。 When the maximum image height is Imax and the distance from the aperture to the image plane is L,
0.5 <L / (2 × Imax) <10 (2)
The optical system according to claim 1, wherein the following condition is satisfied.

後群第１反射面の曲率をＲ１、後群第２反射面の曲率をＲ２とするとき、
０．２＜Ｒ１／Ｒ２＜５・・・（３）
なる条件を満足することを特徴とする請求項１乃至請求項１２のいずれかに記載の光学系。 When the curvature of the rear group first reflecting surface is R1, and the curvature of the rear group second reflecting surface is R2,
0.2 <R1 / R2 <5 (3)
The optical system according to claim 1, wherein the following condition is satisfied.

請求項１乃至請求項１３のいずれかに記載の光学系を用いた内視鏡。 An endoscope using the optical system according to any one of claims 1 to 13.