JP3255730B2 - 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 stereoscopic fundus camera suitable for photographing without using a mydriatic (non-mydriatic).

[0002]

2. Description of the Related Art Conventionally, a reflected light beam incident from an eye fundus through an objective lens is split by a two-hole aperture, and each split light beam is guided to a pair of imaging optical systems to enable simultaneous stereoscopic viewing. Cameras are known. Regarding a non-mydriatic retinal camera, Japanese Patent Publication No. 39-14413 and Japanese Patent Publication No. 53
There are many known examples such as JP-A-43277 and JP-B-56-7693, but all of them disclose only a fundus camera for monocular photography, and use two optical axes for the observation and photography optical system. There is no disclosure of a stereoscopic fundus camera. It is for the following reasons. In non-mydriatic imaging, the subject's eye is miotic in one flash, and continuous imaging cannot be performed. Therefore, the condition for non-mydriatic imaging is to reliably capture an image in one flash. However, it is desired that the photographable pupil diameter be as small as possible. However, in the case of stereoscopic imaging, it is necessary to extract two imaging light beams from the left and right sides of the optical axis on the pupil, so that the minimum pupil diameter required to extract the light beams increases. Therefore, non-mydriatic photography requiring small pupil diameter-compatible performance has been considered to be unsuitable for a stereoscopic fundus camera.

[0003]

The stereoscopic fundus camera is said to be highly useful for diagnosing glaucoma cases, particularly the temporal change in the progress of symptoms. Its use is contraindicated as it causes deterioration. Therefore, there is a problem in that the use of the stereoscopic fundus camera is limited even in cases where the usefulness is high. An object of the present invention is to provide a non-mydriatic stereoscopic fundus camera capable of stereoscopic imaging in view of the above problems.

[0004]

The stereoscopic fundus camera according to the present invention has the following configuration to achieve the above object. (1) In a stereoscopic fundus camera that divides a reflected light beam from the fundus with a two-hole aperture and stereoscopically observes and stereoscopically photographs the fundus of the eye to be inspected , an infrared ray that does not transmit visible light but transmits infrared light to the observation illumination light path. A filter is provided, and the observation optical path
Place a camera with sensitivity and conjugate with the pupil plane.
Each aperture of the two-aperture stop located at the position
For this reason, it is necessary to use a deformed shape that is longer in the vertical direction than in the horizontal direction.
First, the stereo luminous flux passes through, converted to the shape at the pupil plane
The distance between the bases is a distance at which a three-dimensional effect can be obtained .

(2) In the stereoscopic fundus camera according to (1), each of the apertures has an outermost side of 2 mm or less from the optical axis.
It is characterized by having.

[0006]

[0007]

[0008]

[0009]

[0010]

An embodiment of the present invention will be described below with reference to the drawings. [Structure] FIG. 1 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. 2 is a cross-sectional view of the photographing optical system of FIG. 1 taken along line AA, and FIG. 3 is a sectional view of the observation optical system of FIG. 1 taken along line BB.

(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 an infrared filter which makes observation illumination light invisible light,
Reference numeral 4 denotes a flash lamp as a photographing illumination light source, and reference numeral 2 'denotes a flash lamp condenser lens. Reference numeral 5 denotes a beam splitter, 6 denotes a condenser lens, and 7 denotes a ring slit which is a ring-shaped aperture stop. 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. A halogen lamp for observation and a flash lamp for photographing are arranged at conjugate positions by condenser lenses 2 and 2 ′, and both light beams are coaxially combined via a beam splitter 5 to illuminate a ring slit 7. The luminous flux of the ring slit 7 is transmitted through the relay lenses 9 and 1.
An intermediate image is formed in the vicinity of the opening of the perforated mirror 12 by 1, reflected by the donut-shaped mirror surface, becomes coaxial with the optical axis of the objective lens shown in 13, and is formed near the pupil of the eye 14 to be examined. The image of the ring slit 7 is formed, diffused in the eye 14 to be examined, and illuminates the fundus.

(Shooting optical system) 13 is an objective lens shared with the illumination optical system, and 15 is a two-hole aperture for dividing 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. Reference numerals 16 and 17 denote light beam splitting prisms, 16 serves to switch the left and right of the bisected light beam, and 17 serves to place 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 can be moved in the optical axis direction and can be adjusted according to the refractive power of the eye to be examined. 22
Is a return mirror for the observation optical system, and retreats to the position shown by the broken line during photographing. Reference numeral 20 denotes an imaging lens which forms a fundus image on a film surface 21.

Next, details of the shape of the two-hole aperture 15 will be described. The reflected light from the fundus of the eye to be examined 14 forms an inverted intermediate image at point A by the lens of the eye to be examined and the objective lens 13, passes through the opening of the perforated mirror 12, and separates the light beam by the two-hole aperture 15. However, since the two-aperture stop is disposed so as to be conjugate with the pupil of the eye to be examined via the objective lens 13, the luminous flux divided into left and right for stereo on the pupil coincides at point A and is separated again. Will be. That is, the size of the light beam for photographing is practically determined on the pupil plane. Also, as mentioned above,
An image of the ring slit 7 of the illumination optical system forms an image near the pupil of the eye 14 to be inspected. As described above, since the ring slit 7 and the two-hole stop 15 are substantially conjugate positions on the pupil, when the ring slit and the two-hole stop on the pupil plane are overlapped, 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. Distance between the passing bases of the left and right stereo luminous fluxes on the pupil plane (stereo base)
Is set to a dimension (3 mm) for obtaining a sufficient three-dimensional effect, and furthermore, a performance corresponding to a small pupil diameter (4 mm or less) is achieved. It has a vertically long shape so as to have an area equivalent to the light beam. Such computationally approximately 1.8 mm ² becomes a photographing light beam shape with respect to an area 1.77 mm ² when the diameter 1.5mm can be obtained comparable imaging performance. 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.

Further, in this embodiment, the upper and lower cusps of the shape shown in FIG. 7 are slightly cut in the shape of the stop. However, as compared with FIG. It is possible to increase the amount of illumination light flux introduced from above and below within a diameter of 4 mm while avoiding interference between the diaphragm and the stop. Note that the shape of the aperture can be changed within a range in which there is only a slight change in area and no practical problem occurs. 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 mainly 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 addition, even if it is assumed that the pupil diameter of the eye to be examined is sufficient,
It is possible to shoot with a light beam having a sufficient margin, which is more effective.

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 inspected, the luminous flux from the halogen lamp 1 is used as invisible light of the eye to be inspected by the infrared filter 3 at the time of observation.
Are used in synchronism with the return of the return mirror 22, so that a sufficient amount of light is obtained for instantaneous photographing.

(Observation Optical System) The observation optical system is composed of the objective lens 13 of the photographing optical system and the focusing lenses 19a and 19.
The optical system up to b is shared. 23 is a relay lens, 24
Reference numerals a and 24b denote mirrors for directing the light beam inward for the purpose of narrowing the distance between the optical axes. Reference numeral 25 denotes a mirror for directing the light beam in a predetermined direction.
This is a mirror for matching two images. 26 is an imaging lens of the observation optical system, 27 is a CCD sensitive in the infrared region
And the like. The reflected light from the fundus which is guided through the objective lens 13 through the focusing lenses 19a, 19b is reflected upward by the return mirrors 22a, 22b at the positions shown in practice except during photographing. , Relay lenses 23a and 23b, mirror 24
a, 24b and the optical element 25, the light is guided to the image forming lens 26, and forms an image on the image pickup element 27 conjugate with the film surface 21. FIG. 8 shows an example of a TV monitor screen display of an image captured by a TV camera, which is a pair of left and right image displays used for stereoscopic imaging. In this embodiment, an example is shown in which one TV camera and one TV monitor are used. However, dedicated TV cameras are used for left and right images, respectively, and only the TV monitor is shared via an image synthesizing circuit. Any change due to usability, such as using multiple monitors, is acceptable.

[Operation] The operation of the optical system having the above-described configuration will be described. The optical system main body is housed in a casing, and is mounted on an operation table which moves on a fixed table via a sliding mechanism. The photographer fixes the subject on the chin rest fixed to the fixed base. The halogen lamp 1 serving as the observation illumination light source is turned on, and the subject's eye 14 is illuminated with invisible infrared light. The photographer operates the console while watching the observation image appearing on the TV monitor (see FIG. 8), and moves the optical system body back and forth, right and left, and up and down to perform alignment so as to have a predetermined positional relationship. . If you can roughly align, TV
The right and left fundus are observed on the monitor screen as shown in FIG. Then, the photographer finely adjusts the alignment to determine the field of view finely (a well-known alignment index or the like may be used), and turns the focus knob (not shown) to focus.
The focusing lenses 19a and 19b are moved and adjusted to a position where the best focus is obtained (similarly, a configuration according to a focus index or the like may be employed).

When the alignment and focusing are completed,
When the photographing button (not shown) is pressed, the return mirror 22 retreats to the position shown by the broken line, and the xenon flash lamp 4 emits the light in conjunction with it.

Except for the manual operation, a control system including a microcomputer inside the apparatus is used for the operation of the apparatus as described above. The subject's eye 14 responds to the steady light from the xenon flash lamp 4 and causes miosis, but this is after the end of imaging. In addition, although imaging is performed under invisible light illumination, observation and imaging are performed using the natural mydriasis of the pupil in a dark place, so a dark room is used as an imaging environment. As pointed out in the embodiments, the present embodiment can be variously modified, and these modifications are included in the present invention as long as the technical idea is the same as that of the present embodiment.

[0020]

According to the present invention, a non-mydriatic stereoscopic fundus camera capable of stereoscopic photography can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic layout diagram of an optical system when an embodiment of the present invention is viewed from the side.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

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 showing a state in which a ring slit and a two-hole aperture are superimposed.

FIG. 7 is an explanatory diagram illustrating the shape of a two-hole aperture.

FIG. 8 is a diagram showing an example of a TV monitor screen display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Halogen lamp 3 Infrared filter 4 Flash lamp 7 Ring slit 13 Objective lens 14 Eye to be inspected 15 2-hole aperture 21 Film surface 22 Return mirror 27 Image sensor for TV camera

Claims (2)

(57) [Claims] 1. A stereoscopic fundus camera for dividing a reflected light beam from a fundus by a two-hole aperture and stereoscopically observing and stereoscopically photographing a fundus of an eye to be inspected , transmits infrared light without transmitting visible light to an observation illumination light path. An infrared filter is provided, and the observation optical path
With a sensitive camera in the area,
Each aperture of the two-hole stop located in a useful position is
In order to maintain the shape, it should be longer in the vertical direction than in the horizontal direction
At the same time, it is converted into the shape on the pupil plane,
A stereoscopic fundus camera characterized in that a distance between passing bases is a distance at which a stereoscopic effect can be obtained . 2. A stereoscopic fundus camera according to claim 1, before
The outermost of each aperture shall be less than 2mm from the optical axis.
Stereoscopic fundus camera according to claim.