JPH05277078A - Stereoscopic eyeground camera - Google Patents

Abstract

PURPOSE:To enable photographing even when the diameter of pupil is under 4.5mm by a method wherein respective photographing stops for dividing reflected luminous flux are arranged at the position almost conjugate with the pupil of an eye to be inspected with respect to an objective lens so that an image taken has a proper stereoscopic looking and formed longer vertically rather than horizontally. CONSTITUTION:A 2-hole stop 15 which divides a luminous flux into two horizontally for stereoscopic observation and photographing has two openings with irregular shapes formed longer in width vertically rather than horizontally. The reflected light on the eyegrounds of an eye 14 to be inspected passes through an opening of a bored mirror 12 via an objective lens 13 and the luminous flux thereof is separated with the 2-hole stop 15. The 2-hole stop is arranged with respect to the objective lens 13 to be conjugate with the pupil of the eye to be inspected. The luminous flux divided into two on the pupil converges and then, is separated again. That is, a luminous flux for photographing is determined on the surface of the pupil virtually. An image of a ring slit 7 of an illumination optical removal system is formed near the pupil of the eye to be inspected. Thus, the ring slit 7 and the 2-hole stop 15 are located at the positions almost conjugate with the pupil.

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 stereoscopic fundus camera uses a photographic diaphragm arranged at a position substantially conjugate with a pupil to reflect a light beam reflected from the fundus by two.
The light is divided into light beams, and an imaging optical system is provided in each of the divided optical paths. Conventionally, the photographic diaphragm of the device has a small circular shape (round shape). Further, in the stereoscopic fundus camera, the photographing diaphragm 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 diaphragms on the pupil plane, is 3
It is empirically known that when the thickness is at least mm, a sufficient stereoscopic effect can be obtained in fundus observation.

[0003]

Assuming that the stereo base on the pupil is 3 mm and a light beam is introduced with a pupil diameter of .phi.4 mm, only a light beam of .phi.1 mm passes through as in the conventional round diaphragm as shown in FIG. I can not afford to. Since the luminous flux diameter of a general fundus camera is about φ1 and 5 mm, this is 1 / 2.2 in light quantity.
It becomes 5. Further, the relationship of sin ψ = 1.22 × λ / d is established between the eye resolution (ψ) and the pupil diameter (d), which is used, and when d = 1, ψ is about 1.77 °. (Λ = 5
50 nm), when d = 1.5, ψ becomes about 1.18 °,
It is disadvantageous in obtaining the image quality of the fundus of about 1/3. As described above, in the conventional apparatus, if the stereo base is maintained at 3 mm and the diaphragm is made into a small circle shape, the resolution can be increased by enlarging this to obtain a large amount of light or the corresponding eye to be examined. It is necessary for the pupils of the to expand accordingly. This means that if the standard aperture size of a fundus camera is about φ1.5 mm with a stereo base of 3 mm, a pupil size of 4.5 mm or more on the left and right is required. There was a drawback that you could not shoot with the diameter.

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a stereoscopic fundus camera capable of taking a picture even when the pupil diameter φ is less than 4.5 mm while ensuring a stereo base capable of providing a sufficient stereoscopic view on the fundus. To provide. Second of the present invention
The purpose of is 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, the stereoscopic fundus camera of the present invention has the following features. (1) In a stereoscopic fundus camera that splits a reflected light flux from the fundus into two light fluxes, and provides an imaging optical system in each of the split optical paths to perform stereoscopic photography of the fundus, a pupil of the eye to be inspected with respect to an objective lens. The respective photographing apertures, which are installed at substantially conjugate positions and divide the reflected light flux, are arranged so that the photographed image has an appropriate stereoscopic effect based on the stereo base determined on the pupil, and the respective photographing apertures are adjusted. It is characterized by a deformed shape that is longer in the vertical direction than in the horizontal direction.

(2) Each of the photographing apertures of (1) is characterized in that it has an arc which substantially coincides with the diameter when a predetermined small pupil of the eye to be examined is projected onto the photographing aperture.

(3) The predetermined small pupil of (2) is approximately 4 mm.
It is characterized by having a diameter of.

(4) Each of the photographic diaphragms of (2) is characterized by having an arc on the left and right that is substantially the same as the diameter when a predetermined small pupil is projected onto the photographic diaphragm.

(5) Each of the photographic diaphragms in (4) has a shape obtained by partially cutting the upper and lower parts of a shape consisting of left and right circular arcs that substantially match the diameter when a predetermined small pupil is projected onto the photographic diaphragm. Is characterized by.

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

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic layout view of an optical system when an 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 a portion of the photographing optical system of FIG. 2 viewed from above.

(Illumination optical system) 1 is a halogen lamp which is an illumination light source for observation, 2 is a condenser lens for a halogen lamp, 3 is a flash lamp which is an illumination light source for photographing, and 4 is a condenser lens for a flash lamp. 5 is a bee
6 is a condenser lens, and 7 is a ring slit which is a ring-shaped aperture stop. The shape of the ring slit 7 is shown in FIG. Reference numeral 8 is a mirror for changing the direction of the optical path, 9 is an illumination system relay lens, 10 is a reference plate for removing harmful light having a small black spot in the center, 11 is an illumination system relay lens, 12 Is a perforated mirror having an opening for photographing light flux 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, and illuminate the ring slit 7. The luminous flux of the ring slit 7 is mirrored by the relay lenses 9 and 11.
An intermediate image is formed in the vicinity of the opening of 12 and is reflected by the mirror peripheral surface thereof, then becomes coaxial with the optical axis of the objective lens shown in 13, and the image of the ring slit 7 is formed in the vicinity of the pupil of the eye 14 to be inspected. , Illuminates the fundus of the eye 14 to be inspected.

(Photographing optical system) 13 is an objective lens which is shared with the illumination optical system coaxially, and 15 is a two-hole diaphragm which divides a light beam into left and right for stereoscopic observation and photographing.
The two-hole diaphragm 15 has the shape shown in FIG. 5, and has two irregularly-shaped openings that are vertically longer than the left-right width. Each opening is symmetrical and spreads in the vertical direction to increase the opening area. Details of the structure of the two-hole diaphragm 15 will be described later. 1
Reference numerals 6 and 17 denote light beam separating prisms, and 16 has a function of switching the left and right of the divided light beam, and 17 has a function of placing subsequent light beams in parallel at a predetermined interval. Reference numeral 18 is a relay lens, and 19 is a focusing lens, which is movable in the optical axis direction and enables adjustment according to the refractive power of the eye to be inspected. Reference numeral 22 is a return mirror for the observation optical system, which is to be retired at the time of photographing. Reference numeral 20 denotes an imaging lens which forms a fundus image on the film surface of 21.

The details of the shape of the two-hole diaphragm 15 will be described below. 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 aperture of the perforated mirror 12 to separate the light flux by the two-hole diaphragm 15.
Since this two-hole diaphragm is arranged so as to be conjugate with the pupil of the eye to be inspected with respect to the objective lens 13, the light beams divided into right and left for stereo on the pupil match at point A and are separated again. That is, the light beam diaphragm for photographing is practically determined on the pupil plane. Further, the image of the ring slit 7 of the illumination optical system is formed near the pupil of the subject's eye 14. Since the ring slit 7 and the two-hole diaphragm 15 are substantially conjugate with the pupil in this way, when the ring slit and the two-hole diaphragm are superposed on the pupil plane, the result is as shown in FIG. Reference numeral 41 is the aperture of the two-hole diaphragm 15, and 42 is the slit image of the ring slit 7. The distance between the passing bases of the left and right stereo luminous fluxes on the pupil plane (stereo base) is a dimension (3) which gives a sufficient stereoscopic effect.
mm), and each of the left and right luminous fluxes has an area equivalent to that of a luminous flux of φ1.5 mm that maintains the normal photographing performance of the fundus camera. With such a photographing light beam shape, it is calculated to be approximately 1.8 mm.
^It becomes ² , and the same shooting performance can be obtained for an area of 1.77 mm ² at φ1.5 mm. Each aperture is configured to maintain the area balance so that the stereo base does not change with respect to the optical axis, and in the present embodiment, the area balance is maintained as a symmetrical shape.

Further, in the present embodiment, the shape of the diaphragm is slightly cut at the upper and lower sharp corners of the shape shown in FIG. 7, but not only a slight change in area as compared with FIG. It is possible to increase the amount of illumination luminous flux introduced within φ4 mm while avoiding interference with the diaphragm. It should be noted that the shape of the diaphragm can be changed within a range in which a slight area change causes no practical problem. The fundus illuminating light flux by the ring slit 7 introduces the illuminating light flux by utilizing a portion on the pupil plane that does not interfere with these two photographing light fluxes, that is, a portion above and below the vertical dimension of the two light fluxes. In the present embodiment, the shape of the ring slit 7 is designed so that the larger the mydriatic diameter is, the more the light amount enters the fundus. Even if it is assumed that the pupil diameter of the eye to be inspected is sufficiently obtained, it is more effective if the area of the imaging light flux is expanded.

In the above 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 aperture of the perforated mirror 12.
The light flux is separated by the two-hole diaphragm 15. The light flux that has passed through the two-hole diaphragm and has become parallel by the light flux separation prisms 16 and 17a, 17b passes through the relay lenses 18a, 18b and the focusing lenses 19a, 19b, and the imaging lenses 20a, 2b.
At 0b, left and right images are formed on the film surface 21. As the fundus illumination light of the eye to be inspected, the halogen lamp 1 is used at the time of observation, but since the flash lamp 3 is used in synchronization with the leaving of the return mirror 22 at the time of photographing, a sufficient amount of light for photographing can be obtained. Be done.

(Observation Optical System) The observation optical system shares the objective lens 13 to the return mirror 22 of the photographing optical system. Two
3 is an imaging lens for the observation optical system, 24 is a mirror for changing the direction of the optical path, and 25 is a focus glass for the film surface 2
It is arranged so as to be conjugate with 1. Reference numeral 26 is an eyepiece for observing the surface of the focus glass 25. The reflected light from the fundus guided through the objective lens 13 to the focusing lens 19 is reflected upward by the return mirror 22 at the normal stop position that changes the direction of the optical path, and then the mirror 24. An image of the fundus of the eye to be inspected is formed on the surface of the focus glass 25 by the observation system image forming lens 23.
The photographer observes the fundus of the eye to be inspected on the surface of the focus glass 25 through the eyepiece lens 26. When the eye to be inspected has a refractive error, the photographer moves the focusing lens 19 to move the focus glass 25. By performing a focusing operation on the eye fundus of the eye to be inspected, the eye 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 secured while ensuring a stereo base capable of providing a sufficient stereoscopic view at the fundus.
It is possible to provide a stereoscopic fundus camera capable of photographing even when the thickness is less than 4.5 mm. Further, it is possible to obtain an image with a sufficient amount of photographing light with high resolution.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a conventional shooting method using a shooting diaphragm.

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 view of a part of the photographing optical system of FIG. 2 viewed from above.

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

FIG. 5 is a view showing a shape of a two-hole diaphragm 15.

FIG. 6 is a view in which a ring slit and a two-hole diaphragm are superposed.

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

[Explanation of symbols]

 7 ring slit 12 holed mirror 13 objective lens 14 eye to be inspected 15 two-hole diaphragm 16,17 light beam separation prism 20 imaging lens 21 film surface

Claims (6)

[Claims] 1. A light beam reflected from the 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 stereoscopically captures the fundus, each of which is installed at a position substantially conjugate with the pupil of the eye to be examined with respect to the objective lens and divides the reflected light flux. The photographing apertures are arranged so that the photographed image has an appropriate stereoscopic effect based on the stereo base determined on the pupil, and each photographing aperture has a deformed shape that is longer in the vertical direction than in the horizontal direction. A stereoscopic fundus camera. 2. The stereoscopic fundus camera according to claim 1, wherein each of the photographing apertures has an arc that substantially matches a diameter when a predetermined small pupil of an eye to be inspected is projected on the photographing aperture. 3. A stereoscopic fundus camera having a diameter of about 4 mm with the predetermined small pupil of claim 2. 4. The stereoscopic fundus camera according to claim 2, wherein each of the photographing diaphragms has an arc on the left and right that substantially matches a diameter when a predetermined small pupil is projected on the photographing diaphragm. 5. Each of the photographic diaphragms according to claim 4 has a shape in which upper and lower parts of a shape consisting of left and right circular arcs that substantially match a diameter when a predetermined small pupil is projected onto the photographic diaphragm are cut. A characteristic stereoscopic fundus camera. 6. The stereoscopic fundus camera according to claim 1, wherein each of the photographing diaphragms is formed substantially symmetrically.