JP3168224B2 - Stereoscopic fundus camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simultaneous stereoscopic fundus camera, and more particularly to a diaphragm of a stereoscopic fundus camera suitable for a photographing eye having a small pupil diameter.

[0002]

2. Description of the Related Art A simultaneous three-dimensional fundus camera uses a photographic stop arranged at a position substantially conjugate with a pupil to generate two reflected light beams from the fundus.
The light is split into light beams, and an image forming optical system is provided in each of the split light paths. Conventionally, the photographing aperture of the apparatus has been all small circular (round). Further, in the stereoscopic fundus camera, the photographing aperture is arranged at a position substantially conjugate with the pupil, but the stereo base, which is the distance between the centers of the left and right apertures on the pupil plane, is 3
It is empirically known that if the distance is not less than mm, a sufficient three-dimensional effect can be obtained in fundus observation.

[0003]

Assuming that the stereo base on the pupil is 3 mm and a light beam enters at a pupil diameter of φ4 mm, only a light beam of φ1 mm passes through the conventional circular aperture as shown in FIG. I can not afford to. Since the light beam diameter of a general fundus camera is about φ1, 5 mm, this is 1/2.
It becomes 5. In addition, a relationship of sin ψ = 1.22 × λ / d is established between the eye resolution (ψ) and the pupil diameter (d), and when this is used, ｄ is about 1.77 ° when d = 1. (Λ = 5
Nm is about 1.18 ° when d = 1.5,
This is disadvantageous in obtaining about 不 of the fundus image quality. As described above, in the conventional apparatus, if the stereo base is maintained at 3 mm and the aperture is formed in a small circular shape, it is necessary to enlarge the aperture to increase the resolution in photographing, or to obtain a large amount of light, by using the corresponding eye to be examined. Pupils need to be expanded accordingly. This means that if the stereo base is 3 mm and the standard aperture size of the fundus camera is about φ1.5 mm, a pupil size of 4.5 mm or more on the left and right is required, and a pupil size smaller than this is required. There was a drawback that shooting was not possible with a diameter.

An object of the present invention is to provide a stereoscopic fundus camera capable of photographing even when the pupil diameter φ is less than 4.5 mm while securing a stereo base capable of sufficient stereoscopic vision at the fundus in view of the above-mentioned disadvantages of the prior art. To provide. Second embodiment of the present invention
It is an object of the present invention to provide a stereoscopic fundus camera capable of obtaining an image with a sufficient amount of photographing light with high resolution.

[0005]

In order to achieve the above object, a stereoscopic fundus camera according to the present invention has the following features. (1) In a stereoscopic fundus camera that divides a reflected light beam from the fundus into two light beams, provides an imaging optical system in each of the divided light paths, and performs stereoscopic photographing of the fundus, a pupil of the eye to be inspected with respect to an objective lens. The photographic apertures which are installed at substantially conjugate positions and divide the reflected light beam are arranged so that the captured image has an appropriate three-dimensional effect with reference to a stereo base determined on the pupil. It is characterized by having an irregular shape that is longer in the vertical direction than in the horizontal direction.

(2) Each of the photographing apertures in (1) is characterized in that it has a circular arc substantially matching the diameter when a predetermined small pupil of the subject's eye is projected onto the photographing aperture.

(3) The predetermined small pupil of (2) is approximately 4 mm
It has a characteristic diameter.

(4) Each photographing aperture in (2) is characterized in that it has left and right circular arcs substantially matching the diameter when a predetermined small pupil is projected onto the photographing diaphragm.

(5) Each of the photographing apertures in (4) has a shape obtained by partially cutting the upper and lower parts of a shape formed by left and right circular arcs substantially matching the diameter when a predetermined small pupil is projected onto the photographing diaphragm. It is characterized by.

(6) A stereoscopic fundus camera characterized in that each of the photographing apertures in (1) is formed substantially symmetrically.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic layout diagram of an optical system when one embodiment of the present invention is viewed from the side, and includes an illumination optical system, a photographing optical system, and an observation optical system. FIG. 3 is a view of the photographing optical system of FIG. 2 as viewed from above.

(Illumination optical system) 1 is a halogen lamp as an illumination light source for observation, 2 is a condenser lens for a halogen lamp, 3 is a flash lamp as an illumination light source for photography, and 4 is a condenser lens for a flash lamp. 5 is bee
Reference numeral 6 denotes a condenser lens, and 7 denotes a ring slit which is a ring-shaped aperture stop. The shape of the ring slit 7 is shown in FIG. 8 is a mirror for changing the direction of the optical path, 9 is an illumination system relay lens, 10 is a sign plate having a small black spot at the center to remove harmful light, 11 is an illumination system relay lens, 12 Is a perforated mirror having an aperture for photographing light at the center. The luminous flux of the halogen lamp for observation and the luminous flux of the flash lamp for photographing are coaxially combined via the condenser lenses 2 and 4 and the beam splitter 5 to illuminate the ring slit 7. The luminous flux of the ring slit 7 is perforated by relay lenses 9 and 11 to form a perforated mirror.
An intermediate image is formed in the vicinity of the opening 12 and reflected by the mirror peripheral surface, becomes coaxial with the optical axis of the objective lens shown in 13, and forms an image of the ring slit 7 near the pupil of the eye 14 to be examined. Then, the fundus of the eye 14 is illuminated.

(Shooting optical system) 13 is an objective lens which is coaxially shared with the illumination optical system, and 15 is a two-hole stop which divides a light beam into two parts for stereo observation and photographing.
The two-hole aperture 15 has the shape shown in FIG. 5, and has two irregularly shaped openings that are longer than the left and right widths. Each opening is symmetrical and widens in the vertical direction to obtain an opening area. Details of the configuration of the two-hole aperture 15 will be described later. 1
Reference numerals 6 and 17 denote light beam splitting prisms. Reference numeral 16 denotes a function of switching the left and right of the bisected light beam, and reference numeral 17 denotes a function of setting the subsequent light beams in parallel at predetermined intervals. Reference numeral 18 denotes a relay lens, and reference numeral 19 denotes a focusing lens, which is movable in the optical axis direction and can be adjusted according to the refractive power of the eye to be examined. Reference numeral 22 denotes a return mirror for the observation optical system, which retreats during photographing. Reference numeral 20 denotes an imaging lens which forms a fundus image on a film surface 21.

The details of the shape of the two-hole aperture 15 will be described below. The reflected light from the fundus of the subject's eye 14 forms an inverted intermediate image at the point A by the objective lens 13, passes through the opening of the perforated mirror 12, and is separated by the two-hole aperture 15.
Since the two-aperture stop is arranged so as to be conjugate with the pupil of the eye to be examined with respect to the objective lens 13, the luminous flux divided into two parts for the stereo on the pupil coincides at point A and is separated again. That is, the luminous flux stop for photographing is practically determined on the pupil plane. Further, an image of the ring slit 7 of the illumination optical system forms an image near the pupil of the subject's eye 14. As described above, since the ring slit 7 and the two-hole aperture 15 are substantially conjugate with the pupil, when the ring slit and the two-hole aperture are overlapped on the pupil plane, the result is as shown in FIG. Reference numeral 41 denotes an opening of the two-hole aperture 15, and reference numeral 42 denotes a slit image of the ring slit 7. The distance (stereo base) between the passing bases of the left and right stereo luminous fluxes on the pupil plane is set to a dimension (3) for obtaining a sufficient stereoscopic effect.
mm), and the left and right light fluxes have the same area as the φ1.5 mm light flux in which the normal photographing performance of the fundus camera is maintained. Approximately 1.8 mm is calculated for such a luminous flux shape
^{2 and an} equivalent photographing performance can be obtained for an area of 1.77 mm ² at φ1.5 mm. Each aperture is configured to maintain an area balance so that there is no change in stereo base with respect to the optical axis. In this embodiment, the area balance is maintained as a symmetrical shape.

In this embodiment, the shape of the aperture is slightly cut at the upper and lower cusps of the shape shown in FIG. 7. It is possible to increase the introduction amount of the illumination light beam within φ4 mm while avoiding interference between the diaphragm and the aperture. Note that the shape of the aperture can be changed within a range that causes only a slight change in area and does not cause any practical problem. The fundus illumination light beam by the ring slit 7 introduces the illumination light beam using a portion on the pupil plane that does not interfere with the two photographing light beams, that is, a portion above and below the upper and lower dimensions of the two light beams. In this embodiment, the shape of the ring slit 7 is designed such that the larger the diameter of the mydriatic pupil, the more advantageously the amount of light enters the fundus .

In the above-described photographing optical system, the reflected light from the fundus of the eye 14 to be examined forms an inverted intermediate image at the point A by the objective lens 13 and then passes through the opening of the perforated mirror 12.
The light beam is separated by the two-hole aperture 15. The light beams that have passed through the two-hole aperture and become parallel by the light beam splitting prisms 16 and 17a and 17b pass through relay lenses 18a and 18b and focusing lenses 19a and 19b, and are formed into imaging lenses 20a and 20b.
At 0b, the left and right images are formed on the film surface 21. As the fundus illumination light of the eye to be examined, the halogen lamp 1 is used during observation, but the flash lamp 3 is used in synchronization with the withdrawal of the return mirror 22 during photography, so that a sufficient amount of light for photography is obtained. Can be

(Observation Optical System) The observation optical system shares the objective lens 13 to the return mirror 22 of the photographing optical system. 2
3 is an imaging lens for an observation optical system, 24 is a mirror for changing the direction of an optical path, 25 is a focus glass and a film surface 2
It is arranged to be conjugate with 1. Reference numeral 26 denotes an eyepiece for observing the focus glass 25 surface. The reflected light from the fundus guided through the objective lens 13 through the focusing lens 19 is reflected upward by the return mirror 22 at the normal stop position for changing the direction of the optical path, and then reflected by the mirror 24. The fundus image of the subject's eye is formed on the surface of the focusing glass 25 by the observation system imaging lens 23 through the lens.
The photographer observes the fundus of the subject's eye on the surface of the focusing glass 25 via the eyepiece 26, and when the subject's eye has a refractive error, the photographer moves the focusing lens 19 and the focusing glass 25. By performing a focusing operation between the subject and the fundus of the eye to be inspected, the fundus of the eye to be inspected can be focused on the film surface.

[0018]

According to the present invention, the pupil diameter φ can be obtained while securing a stereo base enabling sufficient stereoscopic vision at the fundus.
Is less than 4.5 mm, a stereoscopic fundus camera capable of photographing can be provided. Further, it is possible to obtain an image with a sufficient amount of photographing light with high resolution.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a conventional photographing method using a photographing aperture.

FIG. 2 is a schematic layout diagram of an optical system when the stereoscopic fundus camera of the present embodiment is viewed from the side.

FIG. 3 is a top view of a portion of the photographing optical system of FIG. 2;

FIG. 4 is a view showing the shape of a ring slit 7;

FIG. 5 is a view showing the shape of a two-hole aperture 15;

FIG. 6 is a diagram in which a ring slit and a two-hole aperture are superimposed.

FIG. 7 is a diagram illustrating how to determine the shape of the stop.

[Explanation of symbols]

 Reference Signs List 7 ring slit 12 perforated mirror 13 objective lens 14 eye to be examined 15 two-hole aperture 16, 17 beam splitting prism 20 imaging lens 21 film surface

Claims (6)

(57) [Claims] 1. A light beam reflected from a fundus is divided into two light beams,
An imaging optical system is provided in each of the divided optical paths, and in a stereoscopic fundus camera that performs stereoscopic imaging of the fundus, each of the stereoscopic fundus cameras that is installed at a position substantially conjugate with the pupil of the eye to be examined with respect to the objective lens and splits the reflected light flux The photographic apertures are arranged so that the captured image has an appropriate three-dimensional effect with reference to a stereo base determined on the pupil, and each photographic aperture has a deformed shape that is longer in the vertical direction than in the horizontal direction. 3D fundus camera. 2. The stereoscopic fundus camera according to claim 1, wherein each of the photographing apertures has a circular arc substantially matching a diameter when a predetermined small pupil of a subject's eye is projected onto the photographing aperture. 3. The stereoscopic fundus camera according to claim 2, wherein the predetermined small pupil has a diameter of about 4 mm. 4. A stereoscopic fundus camera according to claim 2, wherein each photographing aperture has left and right circular arcs substantially matching the diameter when a predetermined small pupil is projected onto the photographing aperture. 5. Each of the photographing apertures according to claim 4 has a shape obtained by partially cutting the upper and lower parts of a shape formed by left and right circular arcs substantially matching the diameter when a predetermined small pupil is projected onto the photographing aperture. Features a stereoscopic fundus camera. 6. A stereoscopic fundus camera according to claim 1, wherein each of the photographing apertures is formed substantially symmetrically.