JPS595218A - Large aperture cata-dioptric astronomical telescope with corrected comatic aberration of parabolic reflection mirror - Google Patents

Abstract

PURPOSE:To expand the angle of view with the corrected comatic aberration of a parabolic reflection mirror and to increase an aperture ratio with the reduced focal length of said mirror by disposing a scale-down lens system near the image plane of the parabolic reflection mirror provided in the main barrel of a telescope. CONSTITUTION:A lens group 4 of the two-element constitution consisting of a convex lens G1 having a biconvex face and a concave lens G2 having a biconcave face is disposed on the outside of a main barrel of a telescope. The luminous flux focused by a parabolic reflection mirror 1 mounted in the barrel 2 is drawn to the outside of the barrel 2 by a plane reflection mirror 3 disposed at 45 deg. inclination, whereafter the luminous flux is further focused by a scale down lens system 4, and arrives at an imaging plane 5. The comatic aberration which is the most significant defect with the mirror 1 is corrected by said lens system 4 without spoiling the advantage, i.e., zero spherical and chromatic aberrations, of the mirror 1, whereby the focal length of the mirror 1 is reduced by about 20% and the aperture ratio of the entire optical system is increased.

Description

【発明の詳細な説明】 一般に放物面反射鏡は球面収差及び色収差に関しては無
収差となる利点があるが、一方、周辺像におけるコマ収
差の増大による欠点が大きく、然も口径比が明かるくな
る程、又零角度の大きい徨その影響は著しい。[Detailed Description of the Invention] In general, parabolic reflecting mirrors have the advantage of being free of spherical aberrations and chromatic aberrations, but on the other hand, they have a major disadvantage of increasing comatic aberration in peripheral images, and their aperture ratio is too bright. Indeed, the influence of a large zero angle is significant.

本発明は上記の点に鑑みなされ友もので、放物面反射鏡
のコマ収差を補正し、零角度を拡大させると同時に放物
面反射鏡の焦点圧Ｓｔ短縮することによって口径比を明
かるくする凸レンズ系を放物面反射鏡の像面附近に配し
友人口径反射屈折式天体望遠鏡に関するものである。The present invention was developed in view of the above points, and it corrects the comatic aberration of the parabolic reflector, widens the zero angle, and at the same time shortens the focal pressure St of the parabolic reflector, thereby increasing the aperture ratio. This invention relates to a friend-caliber catadioptric astronomical telescope in which a convex lens system is placed near the image plane of a parabolic reflector.

以下に図示の実施例に基きその内容について説明する。The contents will be explained below based on the illustrated embodiment.

１＃−ｉ望遠鏡水筒２に装着１−である放物面反射鏡で
その入射光側に平面反射鏡３ヲ４５°に傾けて配設しで
ある◎ ４は望遠鏡水筒２の外部に設は念縮小レンズ系で両凸面
を有する凸レンズＧ１と両凹面を有する凹レンズＧ２と
から成る２枚構成のレンズ群で前記した放物面反射鏡１
に入射する光束′ｆ：ｍ弊することがないように望遠鏡
水筒２の外部に配−置しであるう 而して、放物面反射鏡１により集束された光束は４５°
に傾けて配した平面反射鏡３により望遠鏡水筒２の外部
へ引角出されたのち、縮小レンズ系４によってさらに集
束され結像面５に達することとなる。1#-i Mounted on the telescope water bottle 2 The parabolic reflector 1- is placed with a flat reflector 3 tilted at 45 degrees on the incident light side. ◎ 4 is installed outside the telescope water bottle 2. The above-mentioned parabolic reflector 1 is a telescopic reduction lens system and is a two-element lens group consisting of a convex lens G1 having a biconvex surface and a concave lens G2 having a biconcave surface.
The light flux incident on the parabolic reflector 1 is placed outside the telescope water bottle 2 so as not to interfere with the light flux 'f: m.Therefore, the light flux focused by the parabolic reflector 1 is at an angle of 45°.
After the light is drawn out to the outside of the telescope water bottle 2 by the plane reflecting mirror 3 which is arranged at an angle of 1, the light is further focused by the reduction lens system 4 and reaches the imaging plane 5.

前記した縮小レンズ系４は、球面収差及び色収差が零で
ある放物面反射＠１の利点を損うことなく該放物面反射
鏡１の最大の欠点であるコマ収差に対して充分な補ｉＥ
力金有し且つ放物面反射鏡１の焦点用＠を約２０％短縮
させることによって、全光学系の口径比を明かるくする
特質を有するものである＠ 本実施例では、放物面反射鏡ＩＦ１０径１６０ｍｍ。The reduction lens system 4 described above can sufficiently compensate for the coma aberration, which is the biggest drawback of the parabolic reflector 1, without sacrificing the advantage of parabolic reflection @1, which has zero spherical aberration and chromatic aberration. iE
It has the characteristic of brightening the aperture ratio of the entire optical system by shortening the focal length of the parabolic reflecting mirror 1 by about 20%. Mirror IF10 diameter 160mm.

焦点用［１０００隅、口径比６，２５であるが、縮小レ
ンズ系４を付加しプこ甘酸光学系では合成焦点用＠７７
５Ｂ、口径比４．８、有効零角度２．７゜（全角）であ
る。For focusing [1000 corners, aperture ratio 6.25, but with the addition of a reduction lens system 4, for synthetic focusing @77
5B, aperture ratio 4.8, effective zero angle 2.7° (full width).

下記の表Ｆｉ第１図に示し九本実施例の光学系要素を示
したものである。The following Table Fi is shown in FIG. 1 and shows the optical system elements of the nine embodiments.

Ｒ１Ｆｉ各光学面（Ｒｔ〜Ｒｓ　）の曲率半僅山は各光
学面（Ｒ１〜Ｒｓ）の科面間隔Ｎ１Ｆｉレンズ（Ｇｓ、
Ｇ２）の硝子屈折率Ｇｉはレンズ（Ｇｌ、Ｇ２）の１類
（商品名）綴オが、表　焦点用１１１−１．０ 第２図（ａ）〜（由は本発明の実施例に於ける光学系の
追跡、収差曲線図、第５図（１ｍ）〜（由は周辺像の形
状を表わすスポットダイアグラムである。The curvature of each R1Fi optical surface (Rt to Rs) is determined by the surface spacing of each optical surface (R1 to Rs) of the N1Fi lens (Gs,
The glass refractive index Gi of lens (Gl, G2) is 111-1.0 for focusing lens (Gl, G2). Tracking of the optical system, aberration curve diagrams, and Figures 5 (1m) to (1m) are spot diagrams representing the shape of peripheral images.

而して１本発明では斜上の如き構成及び作用を有するも
のであり、特に縮小レンズ系を付加己たことにより放物
面反射鏡のコマ収差を補正し　。One aspect of the present invention has a structure and function similar to that of a diagonal, and in particular, a reduction lens system is added to correct coma aberration of a parabolic reflecting mirror.

零角度を拡大させた明かるい大口径反射屈折式の天体望
遠鏡を得ることが出来る。A bright, large-diameter catadioptric astronomical telescope with an enlarged zero angle can be obtained.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明に係る光学系の概略図と周辺光束の光路
図、第２図（ａ）乃至（ｄ）Ｆｉ本発明実施例に於ける
光学系の追跡、収差曲線図で、第２図（ａ）は球面収差
及び軸土色収差図、第２図伽）は非点収差図、第２図（
ｃ）ｔｉ歪曲収差図、第２図（ｄ）は周辺像に於けるコ
マ収差−＃を示す。 第３図（ａ）乃至（Φは周辺像の形状を表わすスポット
ダイアグラムで、第３図（ａ）ｄ本実施例に於ける周辺
像の形状を５００倍の倍率で示す、第３図（ｂ）Ｆｉこ
のＩｌｔ形成する周辺光束の入射瞳上の形状である。第
５図（ｃ）及び（ｄｌは比較の念め放物面鏡単独に於け
る周辺像の形状及びその周辺光束の入射瞳上の形状を示
す・Fig. 1 is a schematic diagram of the optical system according to the present invention and an optical path diagram of peripheral light flux, Fig. 2 (a) to (d) is a tracking and aberration curve diagram of the optical system in the embodiment of the present invention; Figure (a) is a diagram of spherical aberration and axial chromatic aberration, Figure 2 (a) is a diagram of astigmatism, Figure 2 (
c) Ti distortion aberration diagram, FIG. 2(d) shows coma aberration -# in the peripheral image. Figures 3(a) to (Φ are spot diagrams representing the shape of the peripheral image, Figure 3(a)d, Figure 3(b) showing the shape of the peripheral image in this example at a magnification of 500x. ) Fi is the shape on the entrance pupil of the peripheral light flux formed by this Ilt. For comparison, Figure 5 (c) and (dl) are the shape of the peripheral image in a parabolic mirror alone and the entrance pupil of the peripheral light flux. Showing the shape above・

Claims (1)

【特許請求の範囲】 （１ン雫遠鏡本筒内に配設した放物面反射鏡に、縮小レ
ンズ系を組み合わせ几放物面反射鏡のコマ収差を補正し
た大口径反射屈折式天体望遠鏡 （り　特許請求の範囲第１項の記載に於いて、縮小レン
ズ系を前方に置いた凸レンズＧ１と後方に蓋いた凹レン
ズＧ２とから構成した放物面反射鏡のコマ収差を補正し
友人口径反射屈折式天体望遠鏡[Claims] (Large-diameter catadioptric astronomical telescope in which a reduction lens system is combined with a parabolic reflector disposed in the main barrel of a 1-inch telescope to correct the coma aberration of the parabolic reflector. (ri) In the statement of claim 1, the comatic aberration of a parabolic reflector composed of a convex lens G1 with a reduction lens system placed at the front and a concave lens G2 covered at the rear is corrected to reflect the aperture. refracting astronomical telescope