JPH0412450B2 - - Google Patents

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Publication number
JPH0412450B2
JPH0412450B2 JP58124491A JP12449183A JPH0412450B2 JP H0412450 B2 JPH0412450 B2 JP H0412450B2 JP 58124491 A JP58124491 A JP 58124491A JP 12449183 A JP12449183 A JP 12449183A JP H0412450 B2 JPH0412450 B2 JP H0412450B2
Authority
JP
Japan
Prior art keywords
lens
objective lens
eye
curvature
front lens
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP58124491A
Other languages
Japanese (ja)
Other versions
JPS6017416A (en
Inventor
Fumio Takahashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nikon Corp
Original Assignee
Nippon Kogaku KK
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Kogaku KK filed Critical Nippon Kogaku KK
Priority to JP58124491A priority Critical patent/JPS6017416A/en
Publication of JPS6017416A publication Critical patent/JPS6017416A/en
Publication of JPH0412450B2 publication Critical patent/JPH0412450B2/ja
Granted legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/14—Arrangements specially adapted for eye photography
    • A61B3/15—Arrangements specially adapted for eye photography with means for aligning, spacing or blocking spurious reflection ; with means for relaxing
    • A61B3/156—Arrangements specially adapted for eye photography with means for aligning, spacing or blocking spurious reflection ; with means for relaxing for blocking
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
    • A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
    • A61B3/14—Arrangements specially adapted for eye photography

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Medical Informatics (AREA)
  • Biophysics (AREA)
  • Ophthalmology & Optometry (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Surgery (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Lenses (AREA)
  • Eye Examination Apparatus (AREA)

Description

【発明の詳細な説明】[Detailed description of the invention]

（発明の技術分野） 本発明は眼底カメラにおいて撮影画角の広角化
を非接触で可能とする前置レンズに関する。 （発明の背景） 眼底カメラでは撮影した写真からより有用な情
報を得るために広い範囲を写し込める広角低倍率
写真と、狭画角高倍率写真が必要となつてきてい
る。前者の広角写真を得るには、後者の狭画角写
真のようにリレーレンズに変倍レンズを付加する
といつた簡単な方式では出来ず、一般に広角の眼
底カメラが必要である。そこで、撮影画角を広角
に可変とする方法には、コンタクトレンズによる
方法（例えば特公昭56−33089号公報）とアプラ
ナチツクレンズを付加する方法（特開昭54−
30695号公報）が知られている。しかしながら前
者は取り扱いが不便なこと、後者はアプラナチツ
クレンズ面の曲率の関係から、レンズ面の反射を
除去するためには新たに黒点を配設しなければな
らず、またアプラナチツクレンズのレンズ形状の
ために被検眼からレンズ先端までのいわゆる作動
距離が短かくなつて広角になるにつれて操作性な
どの点で使用しにくくなる欠点があつた。 （発明の目的） 本発明の目的は眼底カメラ本体に付加的な構成
を必要としぜ、しかも長い作動距離を有しつつ優
れた操作性を維持し得る眼底カメラの広角化用前
置レンズを提供することにある。 （発明の概要） 本発明は、穴あき反射鏡を介し対物レンズを通
して被検眼へ照明光を供給し、該穴あき反射鏡の
近傍に配置された開口絞りを通して眼底撮影を行
なう眼底カメラにおける該対物レンズの被検眼側
に、取りはずし可能に装着され、撮影画角の広角
化を可能とするための前置レンズであつて、該前
置レンズの対物レンズ側のレンズ面は、照明光の
この面での反射光に関して開口絞りが対物レンズ
を通して等倍で実の共役関係をなすような曲率を
有し、被検眼側のレンズ面はこの面での反射光に
関して前記開口絞りと共役な位置が該対物レンズ
を通して該対物レンズのレンズ面による該開口絞
りの反射結像位置と一致するような曲率を有する
ものである。すなわち、本発明は非接触型前置レ
ンズであつて、その被検眼側の面はこのレンズ面
による開口絞りの像位置が対物レンズ面のための
反射除去黒点と共役関係にあるように構成すると
共に、穴あき反射鏡側のレンズ面は開口絞りの中
心を発した光が垂直に入射するような曲率に設定
したことを技術的要点としている。そして、この
ような構成により、前置レンズのレンズ面での反
射光除去のために眼底カメラの照明系に新たに黒
点を設ける必要がなくなり、また、前置レンズの
被検眼側のレンズ面による反射光に関して開口絞
りとの共役位置がこの面より穴あき反射鏡側に位
置するため、このレンズ面の曲率半径がアプラナ
チツクレンズである場合よりもかなり大きくな
り、前置レンズとしてのベンデイングが小さく実
質的な作動距離を長くとることが可能となる。 （実施例） 第１図は本発明の実施例の概略構成図であつて
前置レンズLaが眼底カメラの対物レンズL1の被
検眼Ｅ側に配置されている。この図は対物レンズ
L1単独の場合よりも広角化された場合を示して
おり、この前置レンズLaを除けは一般的な眼底
カメラの構成を示している。ランプｌを発した照
明光束はコンデンサーレンズL6で環状開口絞り
Ｓを照明する。この環状開口絞りを通過した光束
はコリメーターレンズL5およびリレーレンズL4
で穴あき反射鏡M1の開口部周縁に環状開口絞り
Ｓの像を形成し、この反射鏡で光束は偏向されて
対物レンズL1および前置レンズLaで被検眼の角
膜付近に再び環状開口絞り像を形成し、被検眼の
眼底を照明する。一方被検眼の眼底を発した撮影
光束は前置レンズLa、対物レンズL1によつて被
検眼の瞳と共役な位置にある開口絞りＰで規制さ
れ、ここでフレアーなど有害な光線が除去され結
像リレーレンズL2でフイルムＦ上に眼底像を結
像する。この像を観察するにはクイツクリターン
ミラーM2を光路中に挿入し、眼底像Ｉを検者ｅ
が接眼レンズL3を通して観察する。眼底カメラ
では照明光が撮影光束中に混入するとコントラス
ト低下、画質の劣化が避けられない。このためた
とえば角膜面での反射は環状開口絞りによつて角
膜周辺から照明し、その中心部から撮影光束を取
り出し混合を防いでいる。また撮影光束を規制す
るために対物レンズに関して被検眼の瞳と共役な
位置に撮影光束を規制するための開口絞りＰを配
置している。従つて、被検眼の瞳と開口絞りの共
役関係は厳密に収差を除去しておく必要があり、
対物レンズL1の一面又は二面に非球面が採用さ
れている。 第２図は本発明に関わる要部で対物レンズL1
および前置レンズLaのレンズ面の反射光を除去
する方法を図示している。対物レンズのレンズ面
による反射光があつてもこの撮影系の開口絞りＰ
の内部を通らなければ問題ない。従つて、この開
口絞りＰを通るような照明光のうちのレンズ面か
らの反射光を遮光してしまえば良い。そこで開口
絞りＰから発した光を被検眼側に追跡していくと
対物レンズの開口絞り側の面r4で屈折されると共
に一部がこの面で反射しB1の位置に虚像を形成
する。屈折された光は被検眼側に進行し対物レン
ズの被検眼側の面r3で再び屈折されると共にここ
でも一部反射して開口絞り側へ戻る。そしてこの
反射光が最終的にr4面で屈折されてB2の位置に反
射像を形成する。従つて、これらB1及びB2の共
役位置を照明系内に求め、その倍率関係から開口
絞りの内部を充分カバーできる大きさの黒点でも
つて遮光すれば対物レンズのレンズ面の反射が完
全に除去可能である。第１図に示した照明系内の
B1′，B2′がこのための遮光部材であり、これは既
に公知の有用な技術である。 さて、第２図に点線で示したごとく前置レンズ
Laを付加しない場合には、対物レンズL1の被検
眼側のレンズ面r3で屈折した光は所定の位置Ｑに
集光しこの位置に被検眼E′を置くことにより通常
の眼底撮影ができる。本発明の前置レンズを付加
した場合は、第２図に実線で示したごとく、前置
レンズLaの対物レンズ側のレンズ面r2は対物レ
ンズL1のみで開口絞りＰと共役関係にある位置
Ｑを曲率中心としており、開口絞りＰから発した
光は前置レンズLaの対物レンズ側レンズ面r2で
反射した場合同一光路をたどり開口絞りＰに戻
る。従つて、前述の環状開口による照明であれば
この開口絞りＰに到達する反射光は存在しない。
また、前置レンズLaの対物レンズ側レンズ面r2
を通過した光は被検眼側の面r1で反射すると開口
絞りＰの方へ戻ることになるが、前置レンズの対
物側レンズ面r2及び対物レンズの各レンズ面r3，
r4で各々屈折され開口絞りＰ側へ射出したときそ
の反射像の位置は、対物レンズ面での反射光に関
して開口絞りＰと共役な位置の１つであるB2に
一致している。このため、前置レンズLaを付加
したときでも新たに反射除去部材を追加する必要
がない。すなわち対物レンズL1のために必要な
反射除去部材B2′が兼用できることになり眼底カ
メラ本器の改造が不要である。 第２図に示した実施例では対物レンズL1の被
検眼側及び穴あき反射鏡側のレンズ面r3，r4につ
いて各々別個に反射除去を行つているが、これら
の面の曲率を変えて各面の反射像位置を一致させ
るように構成することも可能である。 第３図の例は対物レンズの各レンズ面の反射像
位置を一点にほぼ合致させた場合であり、図示し
ていない遮光部材と共役な点B3の１点のみで対
物レンズL1′の反射のみならず前置レンズLa′の反
射除去も可能としている。この場合でも、前置レ
ンズLa′の対物レンズ側レンズ面r2の曲率中心は
対物レンズL1′に関して開口絞りＰと共役な位置
にあつてこの面で光束は垂直入射する構成となつ
ている。また前置レンズLa′の被検眼側レンズ面
r1の曲率は対物レンズL1′の各レンズ面での反射
光除去のために投影される黒点の像位置B3にこ
の面での反射光による開口絞りの像がほぼ合致す
るように構成されている。 従つて、第２図に示した対物レンズにおける反
射光除去用の黒点像位置B2と第３図に示した対
物レンズにおける反射光除去用の黒点像位置B3
とが異なればこれに応じて前置レンズの被検眼側
レンズ面r1の曲率半径も異なるものとなつてい
る。 尚、前置レンズを付加した場合でも開口絞りと
瞳の厳密な共役関係が要求されるので、必要によ
つては前置レンズの１面、ここではr1面を非球面
とすることが望ましい。 以下の表１、表２に、第２図に示した第１実施
例及び第３図に示した第２実施例における前置レ
ンズLa，La′及び対物レンズL1，L1′の諸元を示
す。但し、r1，r2はそれぞれ前置レンズの被検眼
側及び穴あき反射鏡側のレンズ面の曲率半径、
r3，r4は対物レンズの被検眼側及び穴あき反射鏡
側のレンズ面の曲率半径を表わし、d1，d2…は各
レンズの中心厚及びレンズ間隔、ｎは屈折率を表
わし、d0は被検眼の瞳位置から前置レンズの被検
眼側レンズ面の頂点までの距離を表わす。また、
各表中に示した各レンズ面による開口絞りの反射
像位置は、対物レンズの穴あき反射鏡側レンズ面
の頂点からの距離で表わされている。 (Technical Field of the Invention) The present invention relates to a front lens that enables widening of the photographing angle of view in a fundus camera in a non-contact manner. (Background of the Invention) In order to obtain more useful information from photographs taken by fundus cameras, wide-angle, low-magnification photographs that can cover a wide range, and narrow-angle, high-magnification photographs are becoming necessary. In order to obtain the former wide-angle photograph, a wide-angle fundus camera is generally required, rather than using a simple method such as adding a variable magnification lens to a relay lens as in the latter narrow-angle photograph. Therefore, methods for making the shooting angle of view variable to a wide angle include a method using contact lenses (for example, Japanese Patent Publication No. 56-33089) and a method adding an Aplanatic lens (Japanese Patent Publication No. 54-1989).
30695) is known. However, the former is inconvenient to handle, and the latter is due to the curvature of the aplanatic lens surface, so it is necessary to add a new sunspot to remove reflections on the lens surface, and the shape of the aplanatic lens Therefore, as the so-called working distance from the eye to be examined to the tip of the lens becomes shorter and the angle of view becomes wider, it becomes difficult to use in terms of operability. (Object of the Invention) An object of the present invention is to provide a front lens for widening the angle of view of a fundus camera, which does not require an additional configuration on the fundus camera body, has a long working distance, and can maintain excellent operability. It's about doing. (Summary of the Invention) The present invention provides an objective lens in a fundus camera that supplies illumination light to an eye to be examined through an objective lens via a perforated reflector, and photographs the fundus through an aperture diaphragm disposed near the perforated reflector. It is a front lens that is removably attached to the eye side of the lens to enable widening of the photographing angle of view, and the lens surface of the front lens on the objective lens side is used to reflect illumination light. The aperture diaphragm has a curvature such that the aperture diaphragm has a real conjugate relationship at the same magnification through the objective lens, and the lens surface on the subject's eye side has a position that is conjugate with the aperture diaphragm with respect to the light reflected from this surface. It has a curvature that matches the position of the reflected image of the aperture stop formed by the lens surface of the objective lens through the objective lens. That is, the present invention is a non-contact front lens, and its surface on the subject's eye side is configured such that the image position of the aperture stop formed by this lens surface is in a conjugate relationship with the reflection-removal sunspot on the objective lens surface. At the same time, the technical point is that the lens surface on the side of the perforated reflector is set to such a curvature that the light emitted from the center of the aperture stop is incident perpendicularly. With this configuration, there is no need to add a new sunspot in the illumination system of the fundus camera to remove reflected light from the lens surface of the anterior lens, and there is no need to add a new black spot to the illumination system of the fundus camera to remove reflected light from the lens surface of the anterior lens. Regarding reflected light, the conjugate position with the aperture stop is located closer to the perforated reflector than this surface, so the radius of curvature of this lens surface is considerably larger than that of an aplanatic lens, and bending as a front lens is small. It becomes possible to increase the actual working distance. (Embodiment) FIG. 1 is a schematic diagram of an embodiment of the present invention, in which a front lens La is arranged on the eye E side of an objective lens L1 of a fundus camera. This figure shows the objective lens
This shows a case where the angle of view is made wider than when L 1 is used alone, and the configuration of a general fundus camera is shown except for this front lens La. The illumination light beam emitted from the lamp l illuminates the annular aperture stop S through the condenser lens L6 . The light flux passing through this annular aperture diaphragm is passed through collimator lens L5 and relay lens L4.
The image of the annular aperture diaphragm S is formed at the periphery of the aperture of the perforated reflector M1 , and the light beam is deflected by this reflector and returned to the annular aperture near the cornea of the eye to be examined by the objective lens L1 and the front lens La. An aperture image is formed and the fundus of the eye to be examined is illuminated. On the other hand, the photographic light flux emitted from the fundus of the eye to be examined is regulated by the front lens La and objective lens L1 at the aperture stop P located at a position conjugate with the pupil of the eye to be examined, and harmful light rays such as flare are removed here. A fundus image is formed on the film F by the imaging relay lens L2 . To observe this image, a quick return mirror M2 is inserted into the optical path, and the fundus image I is transferred to the examiner e.
observes through eyepiece L 3 . In a fundus camera, if illumination light mixes into the photographing light flux, a decrease in contrast and deterioration in image quality are inevitable. For this reason, for example, reflections on the corneal surface are illuminated from the periphery of the cornea using an annular aperture diaphragm, and the photographing light beam is taken out from the center to prevent mixing. Further, in order to regulate the photographing light flux, an aperture diaphragm P for regulating the photographing light flux is arranged at a position conjugate with the pupil of the eye to be examined with respect to the objective lens. Therefore, it is necessary to strictly eliminate aberrations in the conjugate relationship between the pupil of the subject's eye and the aperture stop.
The objective lens L 1 has an aspherical surface on one or both surfaces. Figure 2 shows the main parts related to the present invention, including the objective lens L 1
and a method for removing reflected light from the lens surface of the front lens La. Even if there is light reflected by the lens surface of the objective lens, the aperture diaphragm P of this photographic system
There is no problem as long as it does not pass through the inside of the Therefore, it is sufficient to block the reflected light from the lens surface of the illumination light that passes through the aperture stop P. When the light emitted from the aperture diaphragm P is tracked toward the subject's eye, it is refracted by the surface r 4 of the objective lens on the aperture diaphragm side, and a portion of the light is reflected by this surface, forming a virtual image at position B 1 . . The refracted light travels toward the eye to be examined, is refracted again at the eye-side surface r3 of the objective lens, and is partially reflected here as well, returning to the aperture stop side. This reflected light is finally refracted by the r4 plane and forms a reflected image at the B2 position. Therefore, if we find the conjugate position of these B 1 and B 2 in the illumination system and block the light with a black dot large enough to cover the inside of the aperture diaphragm based on the magnification relationship, the reflection on the lens surface of the objective lens will be completely eliminated. Removable. In the illumination system shown in Figure 1
B 1 ′ and B 2 ′ are light shielding members for this purpose, and this is a known and useful technique. Now, as shown by the dotted line in Figure 2, the front lens
When La is not added, the light refracted by the lens surface r3 on the eye side of the objective lens L1 is focused at a predetermined position Q, and normal fundus photography is performed by placing the eye E' at this position. can. When the front lens of the present invention is added, as shown by the solid line in Fig. 2, the lens surface r2 of the front lens La on the objective lens side is in a conjugate relationship with the aperture stop P only with the objective lens L1 . The center of curvature is the position Q, and when the light emitted from the aperture stop P is reflected by the objective lens side lens surface r2 of the front lens La, it returns to the aperture stop P along the same optical path. Therefore, in the case of illumination using the annular aperture described above, there is no reflected light that reaches this aperture stop P.
In addition, the objective lens side lens surface r 2 of the front lens La
When the light that has passed through is reflected by the surface r 1 on the side of the eye to be examined, it will return to the aperture stop P.
When the light beams are each refracted at r 4 and emitted toward the aperture stop P side, the position of the reflected image coincides with B 2 , which is one of the positions conjugate with the aperture stop P with respect to the reflected light on the objective lens surface. Therefore, even when the front lens La is added, there is no need to add a new reflection removing member. In other words, the reflection removing member B 2 ′ required for the objective lens L 1 can be used also, and there is no need to modify the fundus camera. In the embodiment shown in FIG. 2, reflection removal is performed separately on the lens surfaces r 3 and r 4 of the objective lens L 1 on the eye side and the perforated reflector side. It is also possible to configure the reflection image position of each surface to match. The example shown in FIG. 3 is a case where the positions of the reflected images of each lens surface of the objective lens are made to almost coincide with one point, and the position of the reflected image of each lens surface of the objective lens is almost coincident with one point, and the position of the reflected image of the objective lens L 1 ' is determined by only one point B 3 that is conjugate with a light shielding member (not shown). It is possible to eliminate not only reflections but also reflections from the front lens La'. Even in this case, the center of curvature of the objective lens side lens surface r 2 of the front lens La' is located at a position conjugate with the aperture stop P with respect to the objective lens L 1 ', and the luminous flux is configured to be perpendicularly incident on this surface. . Also, the lens surface of the front lens La′ on the eye side to be examined.
The curvature of r 1 is configured so that the image of the aperture diaphragm due to the light reflected on this surface almost matches the image position B 3 of the sunspot projected to remove the reflected light on each lens surface of the objective lens L 1 ′. has been done. Therefore, the sunspot image position B 2 for removing reflected light in the objective lens shown in FIG. 2 and the sunspot image position B 3 for removing reflected light in the objective lens shown in FIG.
If the values are different, the radius of curvature of the eye-side lens surface r1 of the front lens is also different accordingly. Note that even when a front lens is added, a strict conjugate relationship between the aperture stop and the pupil is required, so if necessary, it is desirable to make one surface of the front lens, in this case the r1 surface, an aspheric surface. . Tables 1 and 2 below show the specifications of the front lenses La, La' and objective lenses L 1 , L 1 ' in the first embodiment shown in FIG. 2 and the second embodiment shown in FIG. 3. shows. However, r 1 and r 2 are the radius of curvature of the lens surface of the front lens on the eye side and the perforated reflector side, respectively,
r 3 and r 4 represent the radius of curvature of the lens surface of the objective lens on the eye side and the perforated reflector side, d 1 , d 2 ... represent the center thickness and lens spacing of each lens, and n represents the refractive index, d 0 represents the distance from the pupil position of the subject's eye to the vertex of the lens surface on the subject's eye side of the front lens. Also,
The position of the reflected image of the aperture stop by each lens surface shown in each table is expressed by the distance from the apex of the perforated reflecting mirror side lens surface of the objective lens.

【表】【table】

【表】 上記の実施例として示したものは共に、対物レ
ンズL1およびL1′のみの場合には瞳の共役関係の
倍率が約２倍で画角45°を有し、前置レンズLa又
はLa′を付加した場合には瞳の共役関係の倍率が
約３倍で画角65°が可能な例である。 これら本発明に対して、特開昭54−30695号公
報に開示されたアプラナチツクレンズを付加して
広角化を達成する公知のものを比較のために示
す。第４図及び第５図に示した構成は、第２図及
び第３図に示したのと同一の対物レンズL1及び
L1′についてそれぞれ上記本発明による実施例と
等しく画角65°となるようなアプラナチツクレン
ズLb，Lb′を設けたものである。これら公知技術
による第４図及び第５図の構成の諸元をそれぞれ
表３、表４に示す。[Table] In both of the embodiments shown above, when only the objective lenses L 1 and L 1 ' are used, the magnification of the pupil conjugate relationship is approximately 2 times and the angle of view is 45°, and the front lens La Alternatively, when La' is added, the magnification of the pupil conjugate relationship is approximately 3 times, and an angle of view of 65° is possible. For comparison, a known lens which achieves a wide angle by adding an aplanatic lens disclosed in Japanese Unexamined Patent Publication No. 54-30695 to the present invention will be shown. The configuration shown in FIGS. 4 and 5 uses the same objective lens L 1 and
For L 1 ', aplanatic lenses Lb and Lb' are provided so that the angle of view is 65°, which is the same as in the embodiment according to the invention described above. Tables 3 and 4 show the specifications of the structures shown in FIGS. 4 and 5 based on these known techniques, respectively.

【表】【table】

【表】 第４図の構成では第２図の構成と同様に、対物
レンズL1での反射除去のために２個の黒点を必
要とし、第５図の構成では第３図の構成と同様に
対物レンズL1′の反射除去のために１個のみの黒
点を設ける例であるが、アプラナチツクレンズ
Lb及びLb′の数値解から、このレンズの対物レン
ズ側のレンズ面r2による開口絞りの反射像位置を
対物レンズのレンズ面による開口絞りの反射像位
置に一致させることは不可能である。従つて、ア
プラナチツクレンズLb，Lb′の対物レンズ側レン
ズ面r2での反射を除去するには上記の諸元表に示
したごとくこの面による開口絞りＰの反射像位置
Ba及びBbにそれぞれ共役な照明系内の図示しな
い位置に新たに反射除去のための黒点を配設しな
ければならない。 しかも作動距離すなわち前置レンズと被検眼と
の距離についてみれば、第４図、第５図に示した
公知のアプラナチツクレンズの場合にはこのレン
ズの被検眼側レンズ面の曲率中心が被検眼の瞳位
置に一致しており対物レンズ側へ凸面を向けて強
くベンデイングしているため、レンズの周辺部と
被検眼との距離が接近しており実質的な作動距離
が短くなつている。上記の数値例の比較から、前
置レンズがアプラナチツクレンズである公知技術
の場合には、本発明による実施例に比べて約４mm
程作動距離が実質的に短くなつており、この傾向
は広画角になるほど著しくなる。また、アプラナ
チツクレンズの強いベンデイングのために十分な
有効径を持つためにはレンズの中心厚も大きくな
りがちでありこの点でも作動距離の長大化に不利
である。 本発明では、前置レンズの被検眼側レンズ面の
曲率半径は、この面による開口絞りの反射像がこ
の面より穴あり反射鏡側に形成されるように構成
されるため、かなり大きな値となり、前置レンズ
としてのベンデイングが弱いため実質的な作動距
離を長く維持することができる。このために本発
明では前置レンズの形状を下記の条件を満たす構
成とすることが望ましい。 −0.3＜r2＋r1／r2−r1＜−0.8 ここで、r1は前置レンズの被検眼側レンズ面の
曲率半径を表わし、r2は対物レンズ側レンズ面の
曲率半径を表わすものとし、被検眼側に凸な面の
曲率半径を正とする。 （発明の効果） 以上のごとく、本発明によれば広角化前置レン
ズのためにレンズ面反射除去用黒点を新設するこ
となくレンズを付加するだけで良いから簡単に撮
影画角を広角にでき、しかもそのレンズ形状から
作動距離も長くとれて操作性が良くなるという効
果がある。[Table] The configuration shown in Figure 4 requires two black dots to remove reflections at the objective lens L1 , similar to the configuration shown in Figure 2, and the configuration shown in Figure 5 requires two sunspots, similar to the configuration shown in Figure 3. This is an example in which only one black spot is provided to remove reflections from the objective lens L 1 ′.
From the numerical solution of Lb and Lb', it is impossible to make the position of the reflected image of the aperture stop by the objective lens side lens surface r2 of this lens coincide with the position of the reflected image of the aperture stop by the lens surface of the objective lens. Therefore, in order to eliminate the reflection at the objective lens side lens surface r2 of the aplanatic lens Lb, Lb', the position of the reflected image of the aperture stop P by this surface is determined as shown in the specification table above.
New black spots for reflection removal must be provided at positions not shown in the illumination system that are conjugate to Ba and Bb, respectively. Furthermore, regarding the working distance, that is, the distance between the front lens and the subject's eye, in the case of the known aplanatic lens shown in Figures 4 and 5, the center of curvature of the lens surface on the subject's eye side of this lens is located at the subject's eye. Since the convex surface is strongly bent toward the objective lens side, the distance between the peripheral part of the lens and the eye to be examined is close, and the effective working distance is shortened. From the comparison of the above numerical examples, it can be seen that in the case of the known technology in which the front lens is an aplanatic lens, it is about 4 mm smaller than in the example according to the present invention.
As the angle of view becomes wider, the working distance becomes substantially shorter, and this tendency becomes more pronounced as the angle of view becomes wider. Furthermore, in order to have a sufficient effective diameter for the strong bending of an aplanatic lens, the center thickness of the lens tends to be large, which is also disadvantageous in increasing the working distance. In the present invention, the radius of curvature of the lens surface of the front lens on the eye side to be examined is configured so that the reflected image of the aperture diaphragm by this surface is formed on the side of the holed reflector rather than this surface, so the radius of curvature is quite large. Since bending as a front lens is weak, a long effective working distance can be maintained. For this reason, in the present invention, it is desirable that the shape of the front lens satisfy the following conditions. −0.3<r 2 +r 1 /r 2 −r 1 <−0.8 where r 1 represents the radius of curvature of the lens surface of the front lens on the subject's eye side, and r 2 represents the radius of curvature of the lens surface on the objective lens side. The radius of curvature of the surface convex toward the eye to be examined is assumed to be positive. (Effects of the Invention) As described above, according to the present invention, it is possible to easily widen the shooting angle of view by simply adding a lens without newly installing a sunspot for lens surface reflection removal for the wide-angle front lens. Moreover, the lens shape allows for a longer working distance, resulting in improved operability.

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

第１図は本発明の実施の概略構成図、第２図は
第１図の要部を図示したもので本発明の第１実施
例の説明図、第３図は本発明の第２実施例の説明
図であり、第４図、第５図は公知のアプラナチツ
クレンズを使用した前置レンズの構成図である。 （主要部分の符号の説明）、Ｅ……被検眼、
La，La′……前置レンズ、L1……対物レンズ、
M1……穴あき反射鏡、Ｐ……開口絞り、B1，
B2，B3……各レンズ面による開口絞りの反射像
位置。 Fig. 1 is a schematic configuration diagram of the implementation of the present invention, Fig. 2 is an illustration of the main part of Fig. 1 and is an explanatory diagram of the first embodiment of the invention, and Fig. 3 is a second embodiment of the invention. FIG. 4 and FIG. 5 are configuration diagrams of a front lens using a known aplanatic lens. (Explanation of symbols of main parts), E... Eye to be examined,
La, La′...front lens, L 1 ...objective lens,
M1 ...Perforated reflector, P...Aperture stop, B1 ,
B 2 , B 3 ...Position of the reflected image of the aperture stop by each lens surface.

Claims (1)

【特許請求の範囲】[Claims] １ 穴あき反射鏡を介し対物レンズを通して被検
眼へ照明光を供給し、該穴あき反射鏡の近傍に配
置された開口絞りを通して眼底撮影を行なう眼底
カメラにおける該対物レンズの被検眼側に、取り
はずし可能に装着され、撮影画角の広角化を可能
とするための前置レンズであつて、該前置レンズ
の対物レンズ側のレンズ面は、照明光のこの面で
の反射光に関して前記開口絞りが対物レンズを通
して等倍で実の共役関係をなすような曲率を有
し、被検眼側のレンズ面はこの面での反射光に関
して前記開口絞りと共役な位置が該対物レンズを
通して該対物レンズのレンズ面による該開口絞り
の反射結像位置と一致するような曲率を有し、レ
ンズ面の反射除去用黒点を照明系内の共役位置に
新たに配設することなく広角化を可能とすること
を特徴とする眼底カメラの広角化前置レンズ。1. A retinal camera that supplies illumination light to the eye to be examined through an objective lens via a perforated reflector and photographs the fundus through an aperture diaphragm placed near the perforated reflector. A front lens that can be attached to the front lens to widen the photographing angle of view, and the lens surface of the front lens on the objective lens side is connected to the aperture diaphragm with respect to the reflected light from this surface of the front lens. has a curvature such that it passes through the objective lens at equal magnification and has a real conjugate relationship, and the lens surface on the subject's eye side has a curvature that is conjugate with the aperture stop with respect to the reflected light on this surface. The lens surface has a curvature that matches the reflection image formation position of the aperture stop, and it is possible to widen the angle of view without newly arranging a sunspot for reflection removal on the lens surface at a conjugate position in the illumination system. A wide-angle front lens for fundus cameras featuring:
JP58124491A 1983-07-08 1983-07-08 Wide angle conversion pre-lens of fundus oculi camera Granted JPS6017416A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58124491A JPS6017416A (en) 1983-07-08 1983-07-08 Wide angle conversion pre-lens of fundus oculi camera

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58124491A JPS6017416A (en) 1983-07-08 1983-07-08 Wide angle conversion pre-lens of fundus oculi camera

Publications (2)

Publication Number Publication Date
JPS6017416A JPS6017416A (en) 1985-01-29
JPH0412450B2 true JPH0412450B2 (en) 1992-03-04

Family

ID=14886814

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58124491A Granted JPS6017416A (en) 1983-07-08 1983-07-08 Wide angle conversion pre-lens of fundus oculi camera

Country Status (1)

Country Link
JP (1) JPS6017416A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4730910A (en) * 1985-09-18 1988-03-15 Humphrey Instruments, Inc. Wide angle lens system having flare rejection properties

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52141094A (en) * 1976-05-19 1977-11-25 Canon Kk Dental wide angle objective lens
JPS5430695A (en) * 1977-08-09 1979-03-07 Canon Kk Variable angular ophthalmologic device

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS52141094A (en) * 1976-05-19 1977-11-25 Canon Kk Dental wide angle objective lens
JPS5430695A (en) * 1977-08-09 1979-03-07 Canon Kk Variable angular ophthalmologic device

Also Published As

Publication number Publication date
JPS6017416A (en) 1985-01-29

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