JPS6255866B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fundus camera that can selectively perform fluorescent fundus photography and color or monochrome photography (referred to as general photography), and particularly relates to an apparatus that enables wide-angle photography.

The angle of view of non-contact fundus cameras has traditionally been around 30 degrees for a long time, but in recent years, the angle of view has increased to 45 degrees due to the development of wide-angle objective lenses and advances in methods for eliminating harmful reflections and scattering of illumination light beams. It is starting to exceed the However, if wide-angle photography is performed, it becomes possible to photograph a wide area with fewer shots, and since the number of shots is reduced, it is easier to obtain pictures of the same quality, and the pain caused to the patient is also reduced. There is strong hope for further wide-angle expansion.

One of the important requirements for widening the field of view is the removal of the harmful light mentioned above, but in fundus cameras where the imaging system and illumination system are arranged coaxially, part of the illumination system is reflected by the cornea. In order to prevent light from entering the imaging system, a method has long been practiced in which a sunspot is provided in the illumination optical path to block the light reflected by the cornea in advance. However, as objective lenses became wider (45 degrees), harmful light reflected by the crystalline lens became a problem. This is because with a conventional narrow-angle retinal camera (30°), the sunspot shadow, or image, covered not only the reflective area of the cornea but also the crystalline lens. This is because the shadow is shortened and harmful light is also generated in the crystalline lens.

As a countermeasure, Japanese Patent Publication No. 51-24249 removes the light reflected by the lens surface by forming a sunspot image on the front surface or between the front and back surfaces of the crystalline lens, and Japanese Utility Model Publication No. 107140/1980 removes the reflected light from the lens surface A conjugate sunspot is provided in the illumination system to eliminate scattered light within the crystalline lens and the posterior surface of the crystalline lens.

By the way, in the case of a fundus camera, there is a restriction that the fundus illumination beam enters through the pupil of the eye to be examined, so it is desirable to increase the pupil diameter. It becomes difficult to dilate the pupil, so it is necessary to assume that the pupil diameter that can actually be selected is quite small. In addition, in the case of the method for removing harmful light as described above, as the angle of view expands, the area that must be blocked increases, which, together with the limitation of pupil diameter, makes it difficult to completely remove harmful light. exists.

On the other hand, a normal fundus camera can perform not only general photography but also fluorescent fundus photography. In fluorescence fundus photography, the fundus is illuminated with excitation light of a wavelength near blue, timing the time when frioretsen sodium, etc. injected through the cubital vein reaches the intraocular circulation system, and fluorescence is generated from the blood columns. This is performed by photographing only the fluorescent light from among the reflected light from the subject's eye. At this time, a barrier filter is installed in the photographing optical path and an exciter is installed in the illumination optical path to separate wavelengths.

The present applicant previously wrote in Japanese Patent Application Laid-Open No. 55-26959,
Focusing on the fact that the wavelengths of illuminating light and photographing light are separated during fluorescence photography, we proposed increasing the amount of illuminating light by removing the light-shielding plate for removing harmful light. That is, as a result of wavelength separation, light in the illumination wavelength range is blocked by the barrier filter, so even if harmful light within that wavelength range is generated, it will not cause any problems.

An object of the present invention is to enlarge at least the angle of view during fluorescent photography compared to the angle of view during general photography without fundamentally changing the magnification of the imaging optical system.

Examples of the present invention will be described below. In Figure 1,
Ep is the eye to be examined, Ei is its iris, El is the crystalline lens, and Ef
are the same fundus.

In addition, 1 is an observation light source such as a tungsten lamp,
1a is a condenser mirror, 2a and 2b are condenser lenses, 3 is a photography light source such as a xenon discharge tube, 4 is a ring slit plate having an annular opening, and 5 is a mirror.

6a and 6b are relay lenses, and 7 is a mirror-like beam splitter with an aperture in the center. 8 is an objective lens, which is equipped with a front aplanar lens to widen the angle of view. Further, 9 is a focusing lens, 10 is a photographing lens group, 11 is a movable mirror, 12a is a shutter, 12b is a photographic field stop, and 13 is a film. 14 is a field lens, 15 is a mirror,
16 indicates an eyepiece, and Eo indicates the examiner's eye. To summarize the function of this fundus camera, light sources 1 and 3 are almost conjugate with respect to the condenser lens 2a,
Furthermore, a light source image is formed near the ring slit plate 4 by another condenser lens 2b, and then an image of the annular aperture 4 is formed near the beam splitter 7 by relay lenses 6a and 6b. go After the objective lens 8 forms an image of the annular aperture 4 near the iris Ei again, the fundus Ef is illuminated. The above is the illumination system optical path,
The observation light source 1 is turned on during observation, and the photographing light source 3 is turned on during photography.

Furthermore, regarding the imaging system, the reflected light from the fundus Ef travels to the right, and passes through the crystalline lens El and the objective lens 8.
Once imaged by It is guided upward by the movable mirror 11, and the finder (14~
16). When taking a photograph, the movable mirror 11 rotates to the position indicated by the two-dot chain line, the shutter 12a opens, and an image is formed on the film 13.

Next, a member 17 arranged between the mirror 5 and the relay lens 6a is an exciter filter, which is inserted into the illumination optical path during fluorescence photography, and removed from the optical path during general photography. However, after the exciter film is removed, a light-transmitting plate 18 equipped with a light-shielding plate 18a is inserted in its place, the mechanism of which will be described later, and the optical path lengths of the filter and the light-transmitting plate are equal. The light shielding plate 18a is arranged on the optical axis and at a position conjugate with the fundus side surface of the crystalline lens El, and has a function of removing harmful light from the crystalline lens. Note that instead of forming an image of a light-shielding plate within the crystalline lens, it is also possible to form an image of an aperture just in front of the cornea to block the same illumination light beam, and in that case, an aperture is inserted in place of the main light-shielding plate. In addition, if you do not need to consider saving the amount of light, the light shielding plate can be fixed and the exciter filter can be installed or removed at a different position.

Furthermore, 19 is a barrier filter, which can be attached to and removed from the optical path in conjunction with or independently of the filter 17 described above. 20 is an illumination field diaphragm, the specific form of which will be described later. The illumination field diaphragm 20 is arranged, for example, at a position conjugate with the fundus of an emmetropic eye (zero diopter), and is inserted into the illumination optical path in conjunction with the operation of removing the exciter filter 17 from the optical path in the case of general photography to narrow down the luminous flux. . At that time, the amount of narrowing down is
This corresponds to the size of the peripheral area that is not photographed during general photography, and as a result, this peripheral area is shielded from light by the shadow (image) of the aperture. In other words, if the fundus is illuminated beyond the imaging range during general photography,
There is a strong possibility that illumination light that exceeds the imaging range will cause scattering reflection on the fundus surface of the eye and be mixed into the imaging light, resulting in flare, etc. Therefore, it is desirable to block this unnecessary illumination light.

Next, the member 21 immediately in front of the shutter 12 is a light shielding plate with an opening, which has the function of determining the photographing field range for general photographing, and narrows down the luminous flux through the photographing field diaphragm 12b for fluorescence photographing. This light shielding plate 21
is inserted at the position indicated by the broken line in conjunction with the removal of the fluorescent filter, but since this position is extremely close to the film 13, it is substantially conjugated with the fundus Ef.
Further, the narrow photographing field of view when the aperture of the light shielding plate 21 is inserted is the same as the photographing field of view of the photographing angle of view before the present invention was made. (Of course, the photographic field of view may be expanded). Note that if the fundus of the eye to be examined at any diopter and the illumination field diaphragm 20 are adjusted to be optically conjugate with each other in conjunction with focus adjustment, the insertion of the light shielding plate 21 can be omitted, that is, the imaging field diaphragm can be removed or opened. Even if the illumination field aperture 2 at the fundus of the examined eye
By enlarging the size of the aperture image at 0 during fluorescence photography compared to during general photography, it is possible to enlarge the photographing range in which the fundus image is formed during fluorescence photography compared to during general photography, as will be detailed later. Because it is possible.

In the above configuration, in the case of general photography, the light shielding plate 18a is installed on the optical axis instead of the exciter filter 17, and the illumination field diaphragm 20 is inserted or narrowed down, and the barrier filter 19 is replaced with the same optical path length. After inserting the translucent compensating plate 19' and attaching the photographing field diaphragm 21, observation and photographing operations are performed in the same manner as before. Further, fluorescence photography is carried out with the exciter filter 17 inserted in place of the light shielding plate 18a, the photographing field diaphragm 20 and the photographing field diaphragm 21 removed or opened, and the barrier filter 19 inserted. In this case, the irradiation angle of the illumination system and the angle of view of the photographing system are expanded, and a fluorescent photograph with a much wider angle than a photograph taken in general photography can be obtained.

Hereinafter, a detailed explanation will be given of the specific structure for attaching and detaching the fluorescent filter, attaching and detaching the field stop, and confining the field diaphragm. Note that each figure shows the main parts.

FIG. 2 shows a structure in which an illumination field diaphragm plate 20' rotates around a shaft 21 fixed to a bearing 22 and moves in and out of the optical path, but does not move in the direction of the optical axis. Figure 3 shows the illumination field diaphragm plate 20″
In this method, the light beam moves straight along the guide plate 23 to escape from or enter the optical path. In FIG. 4, the illumination field diaphragm 20 is an iris diaphragm equipped with diaphragm blades, and is configured to be opened or squeezed by an opening/closing pin 25 in a diaphragm blade guide plate 24.

When switching between fluorescence photography and general photography, it is possible to change the illumination field diaphragm separately from putting in and taking out the fluorescence filter as described above, but this is not always the case when switching between fluorescence photography and general photography. Since the fluorescent filter is attached and removed, it is a simple and reliable method to link with the fluorescent filter.

The interlocking mechanism is shown in FIGS. 5 to 7.

FIG. 5A shows the case of fluorescence photography. When the fluorescent filter frame 26 is pulled up as shown, the exciter filter 17 comes into the optical path. 1
7' is an optical path correction glass equivalent to an exciter filter. In addition, a light shielding plate 18 for removing harmful light
is installed separately from the optical path correction glass.
Also, if the exciter filter is thin like a gelatin filter, use optical path correction glass 1.
7' is unnecessary. At this time, a barrier filter 19 is installed in the photographing optical path. As is well known, the exciter filter and the barrier filter have different transmission wavelength ranges, so even if the light transmitted through the exciter filter generates scattered harmful light around the fundus, there is no adverse effect on image quality.

FIG. 5B shows the case of general photography. When the fluorescent filter frame 26 is pulled down as shown, the illumination field diaphragm 20' is rotated about the shaft 21 by the spring 25 and is mounted in the optical path. This makes it possible to remove harmful light scattered around the fundus, which affects image quality during general photography.

The same can be said of FIGS. 6 and 7. Fig. 6A shows the illumination field diaphragm 20'' during fluorescence photography, and the illumination field diaphragm 20'' escapes out of the optical path along the guide plate 23 by the fluorescence filter frame 26. Fig. 6B shows the illumination field diaphragm 20'' during general photography. 20' indicates that the fluorescent filter frame 26 is installed in the optical path along the guide 23. FIG. The illumination field diaphragm 20, which is a diaphragm blade, is opened.FIG. 7B shows general photography, and the illumination field diaphragm is closed by an diaphragm opening/closing pin 25 linked to a fluorescent filter.

As mentioned above, the small light-shielding plate 18a shown in FIGS. 5, 6, and 7 is conjugate with the side surface of the fundus of the crystalline lens El, and blocks part of the illumination light to create a shadow on the side surface of the fundus of the crystalline lens. It eliminates reflection and scattering caused by the crystalline lens, and is necessary for general photography. However, in fluorescence photography, wavelength separation is performed using a barrier filter and an exciter filter as described above, so this is not necessary. Therefore, it is conceivable that the light beam be placed in the optical path during general photography, and moved out of the optical path during fluorescent photography. This is shown in Figure 8.

In figure A, there is an exciter filter 17 in the optical path.
In Figure B, the exciter filter 17 is removed from the optical path and the light shielding plate 18a is inserted. Indeed, it is simple and reliable if the mechanism shown in Fig. 8 is operated in conjunction with a fluorescent filter. FIG. 9 shows the interlocking mechanism with the fluorescent filter.

As shown in the figure, it is sufficient to fix it to an optical path correction glass equivalent to a fluorescent filter that enters the optical path during general photography.

The effect of the illumination field diaphragm described above is maximized if it is always located at a position conjugate with the fundus Ef, regardless of the diopter of the eye to be examined. For this purpose, the illumination field diaphragm should also be moved in conjunction with the focus lens 9. Figure 10, 1st
Figure 1 shows the interlocking mechanism of the focus lens and illumination field diaphragm. A focus shaft 29 is connected to a focus knob (not shown). 28 is a focus lever, which is fixed to a focus shaft 29 on the other hand;
On the other hand, as a result of being coupled to the focus lens 9 through a pin and an elongated hole, the focus lens 9 is moved in the optical axis direction by a focusing operation. Reference numeral 27 denotes a movable plate, which can be moved in the optical axis direction of the illumination system guided by a guide mechanism (not shown), and is connected to the aforementioned focus lever 28.
The pin is connected to the oblong hole. Illumination field diaphragm 20'
is attached to a shaft 21 that is integrated with a shaft bearing 22 fixed to a moving plate 27 so as to be rotatable about the shaft 21, although not movable in the optical axis direction. Therefore, when the focus lens 9 moves during the focusing operation, the focal point of the imaging system is adjusted to the fundus.
When the illumination field stop 20' matches Ef, the illumination field stop 20' moves to become conjugate with the fundus Ef. 12 and 13 show a configuration in which various illumination field stops are fixed to a movable plate 27. FIG.

Next, the photographing field diaphragm will be described from FIG. 14 to FIG. 19.

The shape of the aperture is shown at 21' and 2 in Figures 14 and 15.
A light shielding plate such as 1" or an iris diaphragm with a variable aperture diameter as shown in FIG. 16 can be considered.

There are methods as shown in FIGS. 14, 15, and 16 as means for changing the photographing field aperture during fluorescence photography and general photography. Figure 14 shows the shooting field aperture 2.
In this method, the light beam 1' moves away from and enters the optical path with the shaft 30 fixed to the bearing 31 as the center of rotation. In Figure 15, the photographing field aperture 21'' is located at the guide plate 3.
This is a method of escaping from and entering the optical path by moving in a straight line along 2. In FIG. 16, the photographing field diaphragm 21 is a diaphragm blade, and is opened or squeezed by an opening/closing pin 34 in a diaphragm blade guide plate 33. When switching between fluorescence photography and general photography, it is possible to change the photographic field aperture separately from putting in and taking out the fluorescence filter as described above, but when switching between fluorescence photography and general photography, Since the fluorescent filter must be attached and removed, interlocking with the fluorescent filter is a simple and reliable method. Figure 17 - 1st
The interlocking mechanism is shown up to Figure 9.

FIG. 17 shows the case of fluorescence photography. When the fluorescent filter frame 35 is pulled out as shown, the barrier filter 19 is inserted into the optical path. 19' is an optical path correction glass equivalent to a barrier filter.

If the barrier filter is thin like a gelatin filter, the optical path correction glass 19' is not necessary. At this time, an exciter filter 17 is installed in the illumination optical path.

FIG. 17A shows the case of general photography. When the fluorescent filter frame 35 is pushed in as shown, the photographing field diaphragm plate 21' is mounted in the optical path with the shaft 30 as the center of rotation by the spring 36. This makes it possible to remove harmful light scattered around the fundus, which affects image quality during general photography.

The same can be said of FIGS. 18 and 19. Figure 18A shows the time of fluorescence photography, and the photography field aperture 2
1″ is the guide plate 32 by the fluorescent filter frame 35.
It is running away from the optical path. Fig. 18B shows that the photographing field diaphragm 21'' is mounted in the optical path along the guide 32 by means of a fluorescent filter frame during general photography. Fig. 19A also shows the case of fluorescence photography. Aperture opening/closing pin 34 by filter frame 35
The shooting field diaphragm 21 becomes an aperture blade by moving the diaphragm 21.
is left open. FIG. 19B shows general photography in which the photographing field diaphragm is closed by the diaphragm opening/closing pin 34 which is linked to the fluorescent filter.

Next, we will explain how to change the photographic field diaphragm using the aperture just in front of the film camera. Currently, when performing general photography and fluorescence photography, several color images are taken for one patient, and then fluorescence photography is performed, so the type of film is different, so the film camera body must be changed. There is.

Therefore, to change the photographic field of view, it is sufficient to use either a film camera body for general photography with a different aperture just in front of the film, or a film camera body for fluorescent photography. In Fig. 20, H is the main body of the fundus camera, B ₁ is a film camera body for fluorescent photography, and B ₂ is a filter camera body for general photography, and both camera bodies are selectively attached to the main body H. will be installed on the Body B ₁ and body B ₂ use different types of films 13' and 13'', as well as the aperture size d ₁ of the fluorescent field diaphragm 12b and the aperture size d 1 of the general field diaphragm 12b'.
The size d ₂ is different, and as a result, when the film camera body B ₁ for fluorescent photography is attached, the field of view can be captured to the full capacity of the imaging system, and when the film camera body B ₂ for general photography is attached, the field of view can be captured to the fullest extent. A narrower range can be photographed. In addition, when using the method of replacing dedicated camera bodies, a signal pin is installed on each body, and the signal pin is used to attach/detach the fluorescent filter or open/close the illumination field diaphragm. It is also possible.

According to the present invention as described above, it is possible to expand the photographing visual field range in which a fundus image is formed during fluorescence photography, compared to during general photography. This makes it possible to obtain fluorescent photographs with an outstandingly wide angle of view, making it possible to photograph at once a range that was previously limited due to the poor image quality of general photography, making it a great contribution to medical diagnosis. It also has the effect of reducing the need to tilt the entire camera left and right to change the field of view during fluorescence photography. On the other hand, general photography can also be done with the same fundus camera, and in that case as well, extremely good image quality can be obtained. In the above embodiment, one of the illumination field diaphragm 20 and the photographing field diaphragm 21 may be fixed for fluorescence photography, and the aperture of the other may be selectively changed between fluorescence photography and general photography. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention. Second
Figures 3 and 4 are perspective views showing the illumination field diaphragm, Figures 5A and B, Figures 6A and B, Figure 7A,
B is a perspective view showing the interlocking mechanism of the illumination field diaphragm and the fluorescent filter. FIGS. 8A and 8B are perspective views showing an interlocking mechanism between a fluorescent filter and a light shielding plate for removing harmful light. FIG. 9 is a perspective view of the filter frame. FIG. 10 is a perspective view showing a mechanism for displacing a diaphragm in conjunction with focusing, and FIGS. 11, 12, and 13 are perspective views of movable illumination field diaphragms, respectively. 14th
15 and 16 are perspective views showing a photographing field diaphragm, respectively. FIGS. 17A and 17B, FIGS. 18A and B, and FIGS. 19A and 19B are perspective views showing the interlocking mechanism of the photographing field diaphragm and the fluorescent filter, respectively. FIG. 20 is a sectional view of the main parts showing replacement of the film camera body. In the figure, 1 is a light source for festival viewing, 3 is a light source for photography, 7 is a beam splitter, 8 is an objective lens, 9 is a focusing lens, 10 is a photography lens group, 13 is a film,
12a is a shutter, 17 is an exciter filter, 18a is a shading plate for removing harmful light, 19 is a barrier filter, 20 is an illumination field diaphragm, 21 is a photographing field diaphragm, 26 and 35 are fluorescent filter frames,
29 is a focus axis.

Claims (1)

[Scope of Claims] 1. Equipped with a fundus illumination optical system and a fundus photography system, capable of general photography and fluorescence photography, and during general photography, the fundus illumination light and the fundus photography light are spatially separated at the anterior segment of the eye to be examined. Similarly, in a fundus camera that separates fundus illumination light and fundus photographing light in terms of wavelength during fluorescence photography, it is installed at a position that is optically conjugate with the fundus of the examined eye to regulate the imaging field of view where the fundus image is formed. What is claimed is: 1. A fundus camera, comprising: a field diaphragm; and an enlarging means for enlarging a photographing field range in which a fundus image is formed by the field diaphragm during fluorescence photography, compared with that during general photography. 2. The field diaphragm is located in the optical path of the fundus illumination optical system, and the enlarging means expands the photographic field range in which the fundus image is formed by enlarging the illumination field range of the fundus during fluorescence photography compared to during general photography. A fundus camera according to claim 1. 3. The fundus camera according to claim 1, wherein the field diaphragm is located in the optical path of the fundus photographing system and expands the photographing field range in which a fundus image is formed during fluorescence photographing compared to during general photographing. 4. A filter for fluorescence photography is inserted into the optical path during fluorescence photography, and the enlarging means expands the photographic visual field range in which the fundus image is formed as the filter for fluorescence photography is inserted into the optical path. A fundus camera according to scope 1. 5. The fundus camera according to claim 2, wherein the field stop is movable in the optical axis direction during focusing. 6. The fundus camera according to claim 3, wherein the field diaphragm is provided near a photographic film. 7. The fundus camera according to claim 6, wherein the field stop is provided within a film camera body that is attached to and detached from the fundus camera.