JPH01195838A - fundus camera - Google Patents

Abstract

PURPOSE:To remove harmful reflecting light effectively, reduce any unevenness of an illuminating quantity of light on an examinee eyeground and to make the flux of a photographing beam effectively utilizable by constituting an axial shading member into a noncircular form of a form almost similar to a camera part mask. CONSTITUTION:A retinal camera 1 consists of an illuminating system 2 and a photographing system 4. This illuminating system 2 is made up of setting up an observation illuminant 6, a first condenser lens 8, a photographing illuminant 10, a second condenser lens 12, a lighting diaphragm 14, a mirror 16, a relay lens 18 and a perforated lens 20 along an illuminating beam on an illuminating optical axis 5. The lighting diaphragm 14 consists of ringlike diaphragms 21-23, and an axial shading member for these ringlike diaphragms 21-23 is formed into a noncircular form of almost similar form as each opening of a photographing diaphragm 62 and a field mask 70. The photographing system 4 consists of an objective lens 52, a perforated mirror 20, the photographing diaphragm 62, a focusing lens 64, and imaging lens 66, a return mirror 68, the field mask 70 and a film 72.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fundus camera that can remove harmful reflected light from the anterior segment of an eye to be examined and take clear pictures of the fundus.

BACKGROUND OF THE INVENTION Conventional fundus cameras employ a so-called ring-shaped illumination method in order to remove harmful light reflected by the anterior segment of the eye, such as the cornea and crystalline lens of the eye to be examined. That is, by projecting the illumination light flux through a ring-shaped diaphragm having a circular axial light shielding member and extracting the photographing light flux through a photographing diaphragm having a ring-shaped aperture, the anterior segment of the subject's eye is blown and illuminated. The passage areas of the light flux and the photographing light flux are separated from each other.

On the other hand, 35 mm film or instant film with a horizontally elongated photosensitive area is generally used to take fundus photographs, and in order to effectively use the photosensitive area of these films, the effective photographic field of the fundus image is not circular but horizontally elongated. It has a so-called oval shape.

However, in conventional fundus cameras, even if such an oval-shaped photographing field is adopted, the shapes of the axial light shielding member of the ring diaphragm of the illumination system and the photographing diaphragm are circular as before.

Problems to be Solved by the Invention In the conventional fundus camera described above, the size of the axial light-shielding member of the ring-shaped diaphragm in the illumination system and the size of the photographing diaphragm in the photographing system are such that a clear fundus photograph can be obtained over the entire photographic field. For photographing, the angle of view of the oval-shaped photographing field, that is, the maximum angle of view in the horizontal direction, is used as a reference to determine the illumination light flux and the photographing light flux so that they do not overlap in the anterior segment of the subject's eye.

However, as the angle of view increases, the size of the axial light-shielding member of the ring-shaped diaphragm in the illumination system must be increased to remove harmful reflected light. The problem of unavoidable problems is that the amount of illumination light at the periphery of the field decreases, and the difference in the amount of illumination light between the center and the periphery of the field becomes large.

Furthermore, when the photographing angle of view becomes large, the photographing aperture must be made smaller in order to remove harmful reflected light, which also poses a problem in terms of effective use of the photographing light beam.

The present invention has been made in view of these problems of conventional fundus cameras, and it effectively removes harmful reflected light, reduces the unevenness of the amount of illumination on the fundus of the examined eye, and moreover effectively improves the imaging luminous flux. The purpose of this research is to provide a fundus camera for use in the field of vision.

Means for Solving the Problems The fundus camera of the present invention has been developed by focusing on the fact that the vertical angle of view of the horizontal photographing field of the fundus camera is smaller than the horizontal angle of view, and the retinal camera is constructed by focusing on the fact that the angle of view in the vertical direction of the horizontal photographing field of the fundus camera is smaller than the angle of view in the left and right direction. placed in
An illumination system for illuminating the anterior segment of the subject's eye through an illumination diaphragm having an axial light shielding member, and an imaging diaphragm arranged at a position conjugate with the anterior segment of the subject's eye to photograph the anterior segment of the subject's eye. In the fundus camera, the imaging system is provided with a non-circular imaging field mask at a fundus image forming position; It is characterized by having been configured.

The fundus camera of the present invention also includes an illumination system for illuminating the anterior segment of the subject's eye via an illumination diaphragm that is arranged at a position conjugate with the anterior segment of the subject's eye and has an axial light shielding member; and a photographing system for photographing the anterior segment of the eye to be examined through a photographing aperture disposed at a position conjugate with the fundus, the photographing system having a non-circular photographing field mask provided at a fundus image forming position. The camera is characterized in that the photographing aperture is configured to have a substantially similar shape to the photographing field mask.

Embodiments Hereinafter, embodiments of the fundus camera of the present invention will be described based on the drawings. The fundus camera 1 is composed of an illumination system 2 and a photographing system 4.

The illumination system 2 includes an observation light source 6, a first condenser lens 8, a photography light source 10,
Second condenser lens 12, illumination diaphragm 14, mirror 1
6, a relay lens 18 and a perforated lens 20 are arranged. The photographing 1 light source 10 is positioned conjugately with the observation light source 6 with respect to the first condenser lens 8,
The relay lens 18 is positioned so that its front focal position is at the imaging position of the photographing light source 10 by the second condenser lens 12.

The illumination diaphragm 14 is positioned so as to be conjugate with the anterior segment 56 of the eye 54 with respect to the relay lens 18 and the objective lens 52 described below. The illumination diaphragm 14 consists of three ring-shaped diaphragms 21, 22, and 23, and each ring-shaped diaphragm, as shown in FIG. portion 26 are connected by a support portion 28 extending vertically, and the axial light shielding portion 24 and the outer peripheral light shielding portion 2
6, a ring-shaped opening 25 is formed between the ring-shaped opening 25 and the ring-shaped opening 25.

Here, the oval shape generally refers to a shape consisting of straight line parts that are parallel to each other and circular arc parts that connect them, and more specifically, it is defined as a shape that has no tangential discontinuity at the junction of the straight line part and the circular arc part. This term includes an oval shape and a shape that is strictly composed of only a straight line portion and a circular arc portion, and has a corner portion at the joint of the two portions.

The ring-shaped diaphragms 21, 22, and 23 are positioned conjugately with the posterior surface of the crystalline lens, pupil, and cornea of the eye to be examined 54 with respect to the relay lens 18 and the objective lens 52, respectively, and the dimensions of the respective on-axis light shielding portions 24 correspond to the illumination light flux. The area through which the illuminating light beam passes and the area through which the imaging light beam passes are separated in the posterior surface of the crystalline lens, the pupil, and the cornea.

The photographing system 4 includes an objective lens 52, a perforated mirror 20, and a photographing aperture 6 along the traveling direction of the photographing light beam on the photographing optical axis 60.
2. A focusing lens 64, an imaging lens 66, a return mirror 68, a first field mask 70, and a film 72 are arranged.

As shown in FIG. 4, the photographing diaphragm 62 is constructed by providing an oval-shaped opening 82 in a light shielding section 80.

As shown in FIG. 2, the field mask 70 is also configured by providing an opening 86 in a light shielding part 84, and is disposed immediately in front of the film 72.

The objective lens 52 includes a perforated mirror 20 and a photographic aperture 6.
4 and the fundus 58 of the eye 54 to be examined are positioned so that they are almost conjugate, and the focusing lens 60 and the imaging lens 66, which are slidable on the photographing optical axis 60,
8 and film 72 are positioned for military service.

On the observation optical axis 90 reflected by the return mirror 68 inserted in the photographing optical axis 60, along the traveling direction of the reflected light beam of the return mirror 68, a second field mask 92, a field lens 94, a reflection prism 96, and eyepiece 9
8 is placed. The field lens 94 is positioned so that its first surface is conjugate with the photographing aperture 62, that is, the fundus 58, and the film 72. The second field mask 92 is
It is placed just in front of the field lens 94.

In these configurations, the observation light source 6 is turned on during focusing and observation, and the luminous flux emitted from it is restricted by the illumination diaphragm 14 and reflected by the peripheral part of the perforated mirror 20 to illuminate the fundus 58 of the eye 54 to be examined. illuminate. The observation light beam reflected by the fundus 58 forms an image at a position 53, and then passes through the hole of the perforated mirror 20 to the photographic aperture 62.
After being limited by
The image is formed on the first surface of 4. In this visual field, as shown in FIG. 3, an oval-shaped fundus image is formed within the visual field 100, which is observed through the eyepiece 98, and based on this observation, the focusing lens 64 is moved to focus. conduct.

During photography, the photography light source 10 is turned on, and the observation light beam illuminates the fundus 58 in the same way as the observation light beam, and the photography light beam reflected by the fundus 58 travels along the photography optical axis 60 where the return mirror 68 is retracted, and passes through the film 72. A fundus photograph similar to the field of view shown in FIG. 3 above is taken.

In the above embodiment, three ring-shaped diaphragms were used as the illumination diaphragm, but a single ring-shaped diaphragm may also be used.Also, the axial light-shielding part and the outer periphery light-shielding part constituting the ring-shaped diaphragm may be separated. The present invention can be effectively carried out even if it is composed of members and arranged at different positions on the illumination optical axis.

Further, in the case where a plurality of illumination diaphragms are provided, the effects of the present invention can be obtained by making any one of them as in the present invention.

Effects of the Invention As described above, the present invention is constructed by configuring the axial light shielding member to have a non-circular shape substantially similar to the imaging section mask, or by configuring the imaging diaphragm to have a substantially similar shape to the imaging field mask. ,
It is possible to provide a fundus camera that effectively removes harmful reflected light, reduces unevenness in the amount of illumination light on the fundus of the eye to be examined, and effectively utilizes the photographing light flux.

[Brief explanation of the drawing]

Fig. 1 is an optical diagram of a fundus camera according to an embodiment of the present invention, Fig. 2 is a plan view of a field mask, Fig. 3 is a view of the field of view on the first surface of the field lens, and Fig. 4 is a plan view of the photographing aperture. Fifth
The figure is a plan view of the illumination diaphragm. 2...Illumination system 4...Photography system 5...Illumination optical axis 6...Observation light source 10...Photography light source 14...Illumination diaphragm 21.22.23...Ring-shaped diaphragm 24... On-axis light shielding part 25... Ring-shaped opening 26... Outer periphery light shielding part 80... Light shielding part 82... Light shielding part 82... Opening part 84... Light shielding part 86... - Opening 54... eye to be examined

Claims (5)

[Claims] (1) An illumination system for illuminating the anterior segment of the subject's eye via an illumination diaphragm that is arranged at a position conjugate with the anterior segment of the subject's eye and has an axial light shielding member, and a position that is conjugate with the anterior segment of the subject's eye. A fundus camera comprising: a photographing system for photographing the anterior segment of the subject's eye through a photographing diaphragm disposed at the axis; and the photographing system is provided with a non-circular photographing field mask at a fundus image forming position; A fundus camera characterized in that an upper light-shielding member is configured in a non-circular shape substantially similar to the imaging section mask. (2) Claim (2) wherein the non-circular shape is a horizontal oval shape (
1) Fundus camera described. (3) The fundus camera according to claim 2, wherein the illumination diaphragm is a ring-shaped diaphragm in which a circular aperture diaphragm is provided around an axial light shielding member. (4) An illumination system for illuminating the anterior segment of the subject's eye via an illumination diaphragm that is arranged at a position conjugate with the anterior segment of the subject's eye and has an axial light shielding member, and a position that is conjugate with the anterior segment of the subject's eye. A fundus camera comprising: a photographing system for photographing the anterior segment of the subject's eye through a photographing aperture located at the photographing aperture; A fundus camera characterized by having a shape substantially similar to that of an imaging field mask. (5) Claim (5) wherein the non-circular shape is a horizontal oval shape (
4) Fundus camera described.