JPS6254495B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides focusing using a beam that does not cause pupil contraction reaction like infrared rays;
The present invention relates to an observation device for a fundus camera suitable for a non-mydriatic method, which takes into consideration the initial positioning of the fundus camera with respect to the eye to be examined, that is, pupil positioning, prior to subsequent photographing using visible light such as strobe light. Conventional fundus cameras use visible light to focus, determine the field of view, and take pictures, which causes the inconvenience of pupil constriction in the subject's eye.To avoid this, mydriatics are not used. It had to be done. However, this mydriatic agent not only causes great discomfort to eye function, but also has the risk of inducing latent glaucoma, and therefore, a fundus photography method that does not use a mydriatic agent is desired. A fundus camera that uses invisible light to adjust the focus of the pupil in a naturally mydriatic state without using a mydriatic agent is described in Japanese Patent Publication No. 14413/1983. This fundus camera illuminates the fundus with infrared rays during focus adjustment, and observes this using an image tube combined with a photographing optical system. Focus adjustment is performed by adjusting the photographing optical system while observing the fundus image displayed on the image tube. However, although there is no need to use mydriatics with this camera, the focus adjustment is done by setting a focus target on the fundus image displayed on the image tube and using the sharpness of this as a guide, so it is difficult to adjust the focus based on the hue of the fundus. Contrast is difficult to obtain and camera operation is difficult and requires skill. On the other hand, before focusing or photographing a fundus camera, it is necessary to perform pupil positioning to align the objective lens with respect to the pupil of the eye to be examined.
When bright observation light is directed from the objective lens toward the eye to be examined as in a conventional fundus camera, the examiner directly compares the light ring, which is an image of the ring slit, with the pupil of the eye to be examined from the side of the fundus camera. The fundus camera was moved and the objective lens was aligned with the pupil.

However, when a beam that does not reduce the pupil is used during observation, it is difficult for the examiner to visually recognize the image of the ring slit, so the above-described pupil positioning method cannot be used.

By the way, Japanese Patent Publication No. 17707/1989 discloses an observation device for a fundus camera that can observe the fundus and pupil of an eye to be examined in such a manner that the pupil image of the eye to be examined is shifted from the fundus image of the eye to be examined.

In Japanese Patent Publication No. 40-17707, the optical system is moved when focusing, but at that time,
As the pupil image moves with the movement, an after-focal area is formed in the photographing optical system.

This necessitates adding an unnecessary optical component to the photographing optical system, that is, an unnecessary relay section for the light flux, which leads to the complexity and length of the system.

An object of the present invention is to provide a device that solves the above-mentioned problems.

FIG. 1 shows an optical system according to an embodiment of the present invention. In the figure, 1 is an objective lens, 2 is a relay lens, 3 is a film surface, and 4 is an aperture stop, and these four components constitute a photographing system. E is an eyeball placed at a predetermined position in front of the fundus camera, and the objective lens 1 forms an image of the fundus Ef of the eyeball E as an aerial image, and the relay lens 2 transfers this aerial image to the film surface 3 and Film surface 3 regarding reversing mirror 28
The image is refocused on the symmetrical plane F ₃ (described later). A color film or the like is placed on the film surface 3, and the fundus Ef
Record the image. 5 is a focus index light source, 6 is an aperture stop, 7 is a condenser lens, 8 is an infrared transmitting visible light reflection filter, 9 is a split image prism, 10 is a focus index (in this example, the second
As shown in the figure, it is a thin line-shaped slit), 1
1 is a slit (in this example, it is a 2-hole slit as shown in FIG. 2), 12 is a relay lens,
13 is an optical path splitting means (in this example, it is a partially reflective transparent plate in which a small area of a transparent plate is coated with a reflective film 13' as shown in FIG. 2), 14 is a relay lens, and 15 is an optical path splitting device. means (in this example, it is a perforated mirror as shown in Fig. 2), and the above
The eleven lenses and the objective lens 1 constitute a focus index projection system. In the embodiment shown in FIG. 1, the relay lens 2,
14 are optically equivalent and arranged symmetrically with respect to the perforated mirror 15. The light emitted from the light source 5 passes through an aperture diaphragm 6 and is focused onto a focus index slit 10 by a condenser lens 7. An infrared transmitting and visible light reflecting filter 8 is disposed between the lens 7 and the index 10. Therefore, in the optical path of the focusing index projection system after this filter 8, the visible component is removed from the beam, leaving only the infrared beam.
Therefore, the eye E cannot sense the beam from the focus indicator projection system. A split image prism 9 (in this example, it has a shape as shown in FIG. 3 and splits one beam into two beams) is arranged near the index 10, so that the prism 9,
The infrared beam passing through the focus indicator slit 10 is divided into two to become a focusing infrared beam Ip. A perspective view of the arrangement of the light source 5 up to the two-hole slit 11 is shown in FIG. The relay lens 12 partially reflects the image of the index 10 through the reflecting portion 1 of the transparent plate 13.
The image is focused on 3'. This imaging point F ₁ is located on the conjugate plane of the film surface 3. (In this example, the relay lenses 2 and 14 are optically equivalent and are arranged symmetrically with respect to the perforated mirror.) The infrared beam Ip reflected here passes through the relay lens 14 and passes through the ring slit 27 (described later). ), is reflected by the perforated mirror 15, is focused at or near the back focal point _F2 of the objective lens 1, and then passes through the objective lens 1 and the crystalline lens El of the eyeball E, and is projected onto the fundus Ef. be done. The focus of the eyeball E is adjusted to infinity, and the infrared beam Ip for focusing
is focused on the back focal point _F2 of the objective lens 1, the beam Ip passing through the objective lens 1 becomes a parallel beam of light and is therefore accurately focused on the fundus Ef, as shown in Fig. 4A. An image 10' of the focus index slit 10 is focused on the fundus Ef as shown in FIG. If the focus indicator slit 10 cannot be accurately imaged on the fundus due to an abnormality in the refractive power of the eyeball E, the image of the indicator 10 will be focused on the two-hole slit 1 on the pupil as shown in FIGS. 4B and C.
The two holes of image 1 are separated according to the angle at which one point on the fundus Ef is viewed, creating an image of 10".The separated focus index image 10" is transferred to the focus index slit 10.
To match the shape, focus the infrared beam IP
The focal position of the relay lens 14 may be moved an appropriate distance along the optical axis from the rear focal point _F2 of the objective lens 1. Here, the two-hole slit 11 is placed at the rear focal position of the relay lens 12, and the two holes are included in the slit portion of the image of a ring slit 27 (described later) formed by the relay lens 14 and the relay lens 12. They are arranged so that a straight line connecting the centers of the holes lies on the diameter of the image of the ring slit 27. The aperture diaphragm 6 has an aperture size determined so that the light beams from the index illumination light source 5, which are separated into two by the split image prism 9, pass through separate holes of the two-hole slit 11 and do not interfere with each other. The two-hole slit 11 is the condenser lens 7
It is placed near the position where the image is formed.

16 is a light source for fundus illumination, 18 is an infrared transmitting visible light reflecting filter, 19 is a condenser lens, 20 is a reversing mirror, 21 is a strobe light source, 2
3 is a condenser lens, 25 is a ring slit, 26 is a relay lens, and 27 is a ring slit. The above nine elements, the relay lens 14, the optical path splitting means 15, and the objective lens 1 constitute a fundus illumination system. The light emitted from the fundus illumination light source 16, including a portion of the light reflected by the concave mirror 17, passes through a condenser lens 19, an inverting mirror 20, and a field lens 24, and is collected onto a ring slit 25. The light with one point on the ring slit 25 as a secondary light source is once turned into a parallel beam by the relay lens 26 placed so that the rear focal point intersects with the optical axis of the ring slit 25, and then the total reflection surface is turned into a parallel beam. The image passes through the transparent part of the partially reflective transparent plate 13 held in one part, and is then formed by the illumination system relay lens 14 onto the ring slit 27 placed on the front focal plane. It is reflected by the mirror 15 and formed into an image on the pupil of the eye E by the objective lens 1, illuminating the fundus Ef. The ring slit 25 is imaged by the lenses 26 and 14 so that the ring portion coincides with the ring slit 27, and the ring slit 27 is further imaged by the objective lens 1 onto the pupil of the eyeball E. The illumination beam is a parallel light beam between the lenses 26 and 14, and the lenses 14 and 2 are optically equivalent, and the perforated mirror 1
They are arranged symmetrically with respect to 5. Therefore, the part of the fundus image formed on the film surface 3 corresponding to the center of the ring is dark, and the contrast of the focus index projected onto this part is therefore high. Further, by arranging the ring slits 25 and 27 in the illumination beam optical path, the reflected light of the illumination beam by the objective lens and the cornea is prevented from traveling to the film surface 3 based on the principle of the ordinary ring illumination method. Ru. Furthermore, since an infrared transmitting and visible light reflecting filter 18 is disposed between the fundus illumination light source 16 and the condenser lens 19, the light that illuminates the fundus Ef as described above is infrared, which the eye can detect. Not done.

After focusing and determining the shooting field, move the reversing mirror 20 and the partially reflective transparent plate 13 to the dotted line 2.
As shown by 0 and 13, a strobe light source 2 is excluded from the illumination optical path and placed at a position optically equivalent to the light source 16, concave mirror 17, and condenser lens 19.
1. Using a concave mirror 22 and a condenser lens 23, the fundus of the eye is momentarily illuminated and photographed. In this case as well, an infrared filter may be placed in front of the strobe light source 21 and an infrared film may be exposed using infrared rays, but in order to ensure a precise examination, color photography is preferable, and therefore the method shown in Figure 1 is recommended. In this example, no infrared transmitting and visible light reflecting filter is disposed in front of the strobe light source 21.

28 is an optical path splitting means, and in this example, the reversing mirror 30 is a relay lens, 31 is an infrared imaging tube,
32 is a monitor television, and the above four members, the objective lens 1, and the relay lens 2 constitute an observation system. The light from the fundus Ef is focused by the imaging system at the fundus Ef.
When the image is focused on the rear focal point _F2 of the objective lens 1 or its vicinity, the image is formed as an aerial image at or near the rear focal point F2 of the objective lens 1, and then passes through the hole of the perforated mirror 15 and is transmitted to the film surface 3 or the photographing system by the relay lens 2. The image is re-imaged on the symmetry plane F3 of the film surface ₃ with respect to the reversing mirror 28 interposed in the optical path. During the focus adjustment operation, the reversing mirror 28 is placed in the optical path of the photographing system. Therefore, the infrared rays emitted from the focus index photographing system and the fundus illumination system and reflected by the fundus Ef travel backward through the objective lens 1, pass through the relay lens 2, and are reflected by the reversing mirror 28 to reach the plane of symmetry _F3. The image is formed on
The light then passes through a field lens 29 and is imaged by a relay lens 30 on the light receiving surface of an image pickup tube 31 . The infrared imaging tube 31 converts infrared information into an electrical signal and applies it to the monitor television 32. The monitor television 32 converts the electrical signal into a television image and displays the infrared image as a visible image. Instead of the image pickup tube 31 and monitor television 32, other means for converting an infrared image into a visible image, such as an infrared image tube, may be used.

As described above, the focus indicator photographing system and the fundus illumination system share the optical path with the photographing system through the perforated mirror 15 and the observation system through the reversing mirror 28.

Focus adjustment operations and imaging field determination operations are performed by arranging the reversing mirrors 20 and 28 and the partially reflective transparent plate 13 in the optical path of the illumination system and imaging system as shown by the solid line in FIG.
The focus index projection system and fundus illumination system irradiate the fundus Ef with an infrared beam Ip for focusing and an infrared beam for fundus illumination, and the infrared rays reflected from the fundus Ef are visualized and observed using an observation system. It is carried out with An image as shown in FIG. 4 is observed on the image display surface of the monitor 32. For focus adjustment, for example, as mentioned earlier, two relay lenses 2,
14 is optically transparent, so both lenses 2,
14, so that when one lens moves manually or automatically, the other lens also moves transparently, so that the index image on the fundus Ef matches the shape of the index 10. Simply by moving the relay lens 14 along the optical path, the relay lens 2 simultaneously moves optically equivalent to the movement of the lens 14 in response to this movement. Therefore, the focus of the photographing system can be brought into exact alignment with the fundus by a simple operation of moving one of the lenses 2, 14 by an appropriate distance while observing the focus index image displayed on the monitor television 32. However, as shown in the example in Fig. 1, the fundus illumination system and the focus index projection system are
If the relay lens 14 is moved, the illumination condition of the fundus may change, so although it is not shown in the example of FIG. A point on a surface conjugate to the film surface 3 on which the focus index is once imaged.
A mechanical or electrical interlocking means is installed to optically move both _F1 simultaneously along the optical path, and the film surface is moved so that the index image displayed on the monitor television 32 is as shown in FIG. 4A. 3 or the imaging point _F1 by an appropriate distance, the photographing system can be brought into focus accurately on the fundus of the eye. Therefore, at this time, the symmetry plane F ₃ , the field lens 29, the relay lens 30, and the image pickup tube 3
The imaging system including the film surface 3 is moved optically in transmission with the film surface 3 at the same time as the film surface 3 moves. The system in which the relay lenses 2 and 14 are moved relative to each other or the focal length is changed does not share the lens 14 with the fundus illumination system or the relay lens, but has a separate optical path adjacent to the optical path of the index projection system, for example. Just do it like this. By adjusting the photographing system and the focus index projection system in this manner while observing the focus index image on the monitor television 32, the focus of the photographing system can be adjusted to the fundus Ef. In addition, the monitor television 32 displays not only a focus index image but also a fundus image illuminated over a wide area by the fundus illumination system.
By changing the relative direction between the optical axis of the imaging system and the eyeball E, for example, by changing the direction of the camera with respect to the fixed eye, or by changing the direction of the eyeball direction that the subject is gazing at relative to the eyeball. The photographic field of view can then be determined. This is because the optical paths of the observation system and the photographing system coincide (the above-mentioned systems are assembled into one body, for example, and are movable and rotatable on the camera stand).

By the way, in order not to use a mydriatic agent to open the pupil, the eyeball E must be shielded from visible light when adjusting the focus of the fundus camera and determining the photographic field of view. Therefore, pupil alignment is the adjustment of the direction and position of the pupil in order to prevent the film surface 3 from harmful reflected light from the pupil and to keep the objective lens 1 at a predetermined distance from the pupil. It is also necessary to use invisible light.

In the embodiment of FIG. 1, pupil alignment is performed using infrared light. 33 is a light source for pupil alignment, and an infrared transmitting visible light reflecting filter 34
It is arranged so as to face the pupil of the eyeball E across. Reference numerals 35 and 36 are reversing mirrors, which are placed in the optical path between the objective lens 1 and the relay lens 2 and between the relay lens 2 and the film surface 3 to bypass the relay lens 2 during the pupil alignment operation. Open a light path. 37 is an auxiliary objective lens, 38 is a field lens, and 39 is a transparent chart on which a line diagram as shown in FIG. 38 onto a chart 39. Mirrors 42 and 43 bend the optical path of the pupil alignment system. Reference numerals 40 and 41 are relay lenses which re-image the pupil image formed on the chart 39 onto a symmetrical plane F3 with respect to the reversing mirror 28 disposed in the optical path of the film surface ₃ .
Light from the pupil of the eyeball E passes through the objective lens 1, is reflected by a reversing mirror 35 disposed in the optical path of the photographing system, is directed to an auxiliary objective lens 37, and is imaged on a chart 39. The light from this image is mirror 4
2, passes through relay lenses 40 and 41, is reflected by mirror 43, and reversing mirrors 36 and 28 disposed in the optical path of the imaging system, and is imaged on the symmetry plane _F3 . This image is re-focused on the light receiving surface of the image pickup tube 31 by the relay lens 30,
Therefore, the image of the pupil is displayed on the monitor television 32. Film surface 3 is used to focus on the fundus mentioned above.
In the embodiment in which the plane of symmetry F 3 is moved, the plane of symmetry F ₃ also moves, and in correlation to this movement, the relay lens 4 moves.
1 moves along the optical axis to always form a pupil image on the plane of symmetry _F3 . Therefore, the pupil image displayed on the monitor television 32 is always in focus. The pupil position is determined by observing the chart 39 and the pupil image displayed on the monitor television 32, and changing the relative position of the camera eyeball E with respect to the pupil in consideration of the position of the pupil image with respect to the diagram of the chart 39. Matching is done.

In order to photograph the fundus of a subject using the fundus camera of the embodiment shown in FIG.
6 and 28 are placed in the optical path of the imaging system, the light source for pupil alignment is turned on, and the pupil alignment is performed while observing the pupil image displayed on the monitor television 32.
Next, the reversing mirrors 35 and 36 are removed from the optical path, and the partially reflective transparent plate 13 and the reversing mirror 20 are removed from the optical path.
As shown by the solid line in the figure, it is placed in the optical path of the illumination system to illuminate the fundus with infrared rays over a wide area, and also projects a focus index, and then observes the fundus image and focus index image on a monitor TV to determine the field of view and adjust the focus. Then, the reversing mirrors 20 and 28 and the partially reflective transparent plate 13 are removed from the optical path, and the strobe light source 21 is removed.
is issued to expose the fundus image onto the photographic film placed on the film surface 3. Although not shown in Figure 1, lighting of each light source, reversal of each mirror, etc.
This is done by mechanical or electrical means in accordance with a predetermined interlocking relationship.

As described above, according to the present invention, it is possible to observe the pupil image of the subject's eye so that it is coaxial with the fundus image of the subject's eye, and furthermore, it is possible to prevent the apparatus from increasing in length and to achieve downsizing.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of one embodiment of the present invention, Fig. 2 is an explanatory diagram of slits, etc. used in the optical system of Fig. 1, and Fig. 3 is a perspective view of a part of the optical system of Fig. 1. , FIG. 4 is an example of a fundus image and a focus index image displayed on a monitor television. In the figure, 1 is an objective lens, 2 is a relay lens, 3 is a film surface, 5 is a focus indicator light source, 9 is a split image prism, 10 is a focus indicator, 14
15 is a relay lens, 15 is an optical path dividing means, 16 is an illumination light source, 21 is a strobe light source, 28 is an optical path dividing means, 31 is an image pickup tube, and 32 is a monitor television.

Claims (1)

[Scope of Claims] 1. An illumination system that illuminates the eye to be examined; an imaging optical system that has an objective lens facing the eye to be examined and forms a fundus image of the eye to be examined at a predetermined position; an observation system that observes a fundus image; and a mirror that shares the objective lens and is interposed in the imaging optical system between the objective lens and the primary imaging plane of the pupil of the subject's eye formed by the objective lens; Observation of a fundus camera characterized by comprising a pupil image forming optical system that forms an optical path to form a pupil image of the subject's eye at a position conjugate with the fundus so that the pupil image of the subject's eye is coaxial with the fundus image of the subject's eye. position.