JPS6345822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fundus camera for observing and photographing the fundus of the eye, and in particular has a built-in index projection optical system for focusing and is switchable for both mydriatic photography and non-mydriatic photography. It is something.

Conventionally, the general method for focusing a fundus camera is that the observer finely adjusts the focus lens behind the objective lens while looking through an observation eyepiece. However, the conventional method of focusing by matching the cross-hair line with the aerial image of the fundus requires skill, and also causes observer fatigue in group medical examinations. Furthermore, due to the pain and danger to subjects caused by mydriatic drugs, in recent years so-called non-mydriatic fundus cameras, which observe the fundus using infrared light and take pictures using visible light, have become popular for group examinations without using mydriatic drugs. It is used many times, etc. However, in this case as well, the fundus image on the monitor after being converted to visible light is , the contrast is poor and the image quality is insufficient for focusing. To solve this problem,
Recently, a device for projecting a focusing index onto the fundus of the eye has been developed, and an application has already been filed by the applicant. The outline of this device is shown below in Figures 1 to 5.
The diagram will be explained.

FIG. 1 shows a fundus camera capable of switching between a conventional mydriatic method and a non-mydriatic method in which a focusing index can be used only during non-mydriatic imaging. The photographing optical system is composed of an objective lens 1 located in front of the eye E, followed by a focus lens 2, a photographing lens 3, and a film 4. A flip-up mirror 5 is movable between the photographing lens 3 and the film 4. It is freely mediated. A perforated mirror 6 is installed diagonally between the objective lens 1 and the focus lens 2, and in the fundus illumination optical path on the entrance side, a bar mirror 8 whose tip is a reflective surface follows the relay lens 7. The bar mirror 8 can be moved out of the optical path by a solenoid 9. On the incident side of the bar mirror 8, an index projection section 11 for focusing is arranged next to a visible light cut filter 10. The target projection optical system consisting of these 8 to 11 members is mounted on the base plate 12, and the base plate 1
2 is movable in the optical axis direction of the fundus illumination optical path, and is displaced by an interlocking mechanism 13 while maintaining a constant relationship with the focus lens 2.

With the bar mirror 8 removed from the optical path,
The fundus illumination optical system sequentially includes a relay lens 7, a ring slit 15 as shown in FIG. An observation light source 21 consisting of a cut filter 19, a condenser lens 20, and a tungsten lamp is arranged. Note that 22 indicates a reflector of the observation light source 21.

On the other hand, on the reflection side of the flip-up mirror 5, a field lens 23, an optical path switching mirror 24, a television lens 25, and an infrared image pickup tube 26 are sequentially arranged, and the output of the infrared image pickup tube 26 is transmitted to a television monitor 27. It is starting to be shown on the screen. Also, mirror 24
A direct viewing lens 28 is included in the optical path switched by the
are arranged so that the fundus image can be directly observed with the examiner's eye e.

During monitor observation using this fundus camera, the light emitted from the observation light source 21 is transmitted through the condenser lens 20,
It passes through a visible light cut filter 19 and becomes infrared light,
After the light is focused on the photographing light source 18, the condenser lens 1
7 illuminates the ring slit 15. Furthermore,
The infrared light emitted from the ring slit 15 is imaged on the perforated mirror 6 by the relay lenses 14 and 7, and then reimaged near the erythema of the eye E to be examined by the objective lens 1 to illuminate the fundus Ef. . The light reflected by the fundus Ef passes through the objective lens 1, the perforated mirror 6, the focus lens 2, and the photographic lens 3, and then is formed into an image on the field lens 23 by the flip-up mirror 5. An image is formed on the infrared imaging tube 26 and displayed on the television monitor 27 as a monochrome visible light image.

In the illumination light flux, as described above, the base plate 12 that moves in the direction of the fundus illumination optical axis while maintaining a certain relationship with the focus lens 2 is connected by the interlocking mechanism 13, and the base plate 12 is placed on the base plate 12. The focal plane of the index projection unit 11 that is
When the film 4 is in a conjugate position, the index A is aligned in a straight line on the television monitor 27, as shown in FIG. 3a.

However, the human retina has different reflective layers or depths for infrared light and visible light, so when observing and focusing using infrared light and photographing using visible light, it is necessary to focus the infrared light and visible light. Corrections must be made in advance. This corrected focusing index light flux enters the fundus illumination light flux from the index projection unit 11 through the rod mirror 8, passes through the relay lens 7, the perforated mirror 6, and the objective lens 1, and forms an image on the retina of the fundus Ef. . This imaged focusing index passes through the same optical path as the fundus image and is displayed on the television monitor 27 as a split focusing index A. FIG. 3b shows a state in which this focusing index A is split. However, when photographing the fundus Ef, the bar mirror 8 is retracted out of the illumination optical path by the solenoid 9, so that it is not captured in the photograph.

In this way, the focus is confirmed and the shooting light source 1 is
8, the visible light passes through the same optical path as the illumination light and illuminates the fundus Ef, but since the flip-up mirror 5 jumps up in conjunction with the light emission of the photographing light source 18, the fundus Ef
The light from Ef forms an image on the film 4.

In addition, if the observation light source 21 is turned on, the visible light cut filter 19 is removed from the optical path, and the light reflected from the flip-up mirror 5 is guided to the direct viewing lens 28 by rotating the optical path switching mirror 24, the visible light can be used to illuminate the fundus.
Ef can be observed directly. However, in this case, due to the fact that the visible light cut filter 10 is included in the target photographing optical system and that the focus of infrared light and visible light is corrected in the target projection optical system, the focusing index is not used. cannot be used.

As shown in FIG. 4, the index projection unit 11 sequentially projects images from an index light source 30 consisting of a tungsten lamp.
It is composed of an aperture diaphragm 31, a condenser lens 32, a split prism 33, an index plate 34, a two-hole diaphragm 35, and an imaging lens 36, of which the aperture diaphragm 3
1. The index plate 34 and the two-hole aperture 35 are respectively
It has slits or holes shaped as shown in Figures a, b, and c.

Here, the light from the index light source 30 is transmitted to the aperture stop 31.
A split prism 33 is illuminated by a condenser lens 32 through the condenser lens 32. split prism 3
The index plate 34 disposed near 3 is a slit-shaped aperture diaphragm as shown in FIG. 36, it is imaged onto the rod mirror 8 via the visible light cut filter 10. If the position of the reflective surface at the tip of the bar mirror 8 located on the optical axis of the fundus camera passing through the relay lens 7 is conjugate with the fundus Ef, the light from the index plate 34 will pass through the relay lens 7.
After being reflected by the perforated mirror 6, the light passes through the objective lens 1 and forms a straight image on the fundus Ef without being split.

Since the photographing light from the photographing light source 18 is visible light, it is reflected on the retinal surface of the fundus Ef, whereas the focusing index is infrared light, so it is reflected at a layer slightly deeper than the retinal surface. In order to focus while viewing the image on the TV monitor 27, the retinal surface and the film surface must be conjugated, and the infrared light reflecting layer slightly deeper than the retinal surface must be in a conjugate relationship with the imaging plane of the index. The focus lens 2 and the base plate 12 will be interlocked while maintaining these conjugate relationships.

As described above, the conventional fundus camera with a built-in index projection optical system for focusing has the disadvantage that the index can only be used for either mydriatic photography or non-mydriatic photography.

An object of the present invention is to eliminate the above-mentioned drawbacks, to enable a focusing index to be used for both mydriatic photography and non-mydriatic photography, and to enable accurate focusing in both cases without requiring any skill. The purpose is to provide a fundus camera that can be easily and quickly operated.The gist of the fundus camera is to enable switching between both mydriatic and non-mydriatic imaging, and to switch between visible light during mydriatic imaging and red light during non-mydriatic imaging. A focusing target projection optical system that uses external light and is common to both methods, and a correction that corrects out-of-focus caused by the difference in the reflective layer in the fundus retina due to the wavelength difference between visible light and infrared light. It is characterized by comprising means.

The present invention will be explained in detail below based on the embodiments shown in FIG. 6 and below.

FIG. 6 shows only the target projection optical system according to the first embodiment of the present invention, and the other configurations are the same as those in FIG. 1, and numerals 30 to 36 are the same as in FIG. 4. or represents an equivalent member. In this embodiment, the target projection optical system is provided with a visible light cut filter 40 and a solenoid 41 for inserting and removing the visible light cut filter 40 as a mechanism for correcting a focus shift due to a wavelength difference between visible light and infrared light.

Figure 7 shows the difference in the reflection position of infrared light and visible light on the retina Ea.Visible light is reflected on the retinal surface Eb, whereas infrared light is reflected on the retinal surface Ea. The infrared light reflecting layer Ec is as deep as the
reflect. Therefore, if the visible light cut filter 40 is thick enough to extend the optical path length by the distance between the infrared light reflecting layer Ec and the retinal surface Eb, the examiner can use the infrared light when focusing using the infrared light. By aligning the focusing index between the television camera and the television monitor, or in the case of visible light with the naked eye, the retinal surface Eb is constantly adjusted.
You can take photos that are in focus.

Note that the visible light cut filter 40 is inserted and removed using a solenoid 41 shown in FIG. 6, but since the optical characteristics of the filter 40 and its thickness are closely related, the optical path length may be corrected by a device other than the filter 40. Transparent glass may also be used.

FIG. 8 shows a second embodiment, in which a dichroic mirror 42 for reflecting infrared light and transmitting visible light is provided obliquely between an index plate 34 and a two-hole diaphragm 35. Furthermore, an infrared light path from the first index light source 30a to the index plate 34a and a second
Two visible light paths are provided from the index light source 30b to the index plate 34b. In this case, the split prisms 33a and 33b naturally have different prism angles, and a visible light cut filter 43 is inserted in the infrared light path.

In FIG. 8, in the case of non-mydriatic photography in which focusing is performed using infrared light, light from an index light source 30a passes through a visible light cut filter 43, passes through a split prism 33a and an index plate 34a, and is split. , reflected by the dichroic mirror 42, 2
The light passes through the aperture diaphragm 35 and the imaging lens 36, and is imaged onto a focus plane P1 that is conjugate with the infrared light reflecting layer Ec of the fundus Ef.

On the other hand, in the case of mydriatic photography in which focusing is performed using visible light, when the index light source 30b emits light, the light is separated through the split prism 33b and index plate 34b, and transmitted through the dichroic mirror 42. The fundus passes through the two-hole aperture 35 and the imaging lens 36.
An image of Ef is formed on a focus plane P2 conjugate with the retinal surface Eb. Therefore, by switching between the index light sources 30a and 30b, it becomes possible to correct the focus of visible light and infrared light of the index projection optical system for focusing.

FIG. 9 shows a third embodiment in which focusing indicators of visible light and infrared light are always projected, and here the aperture diaphragm 31 has the shape shown in FIG. The dimensions are approximately the same. In addition, vertical slit indicators 44 shown in FIG. 10b made of visible light transmitting/infrared light reflecting filters are used as indicators before and after the split prism 45, and vertical slit indicators 44 made of visible light reflecting/infrared light transmitting filters are used as indicators. 10
Horizontal slit indicators 46 shown in Figure c are arranged with the slits orthogonal to each other. Also,
As shown in FIG. 11, the split prism 45 also has elements 45a and 45c, and 45b and 45d, which are paired in a 180 degree direction, so that the light that has passed through the elements 45a, 45c and 45b, 45d is directed away from each other. A prism angle is provided. Further, in front of the imaging lens 36, a twelfth lens is provided.
A four-hole aperture 47 as shown in the figure is arranged, and these four
Among the holes of the hole aperture 47, holes 47a and 47c, hole 4
7b and 47d are each paired in a 180 degree direction.

In FIG. 9, light emitted from an index light source 30 passes through an aperture diaphragm 31 and then passes through a condenser lens 32.
The vertical slit index 44 that transmits visible light and reflects infrared light is illuminated by the vertical slit index 44, and the visible light emitted from the vertical slit index 44 is separated into two directions by a pair of elements 45a and 45c of a split prism 45. , two holes 47 of a four-hole aperture 47
a, 47c, and is imaged onto the focus plane P2 by the imaging lens 36. At the same time, the light emitted from the index light source 30 passes through the visible light reflection/infrared light transmission filter of the vertical slit index 44 through the condenser lens 32, becomes infrared light, passes through the split prism 45, and illuminates the horizontal slit index 46. and,
Immediately before entering the horizontal slit index 46, the infrared light passes through the elements 45b and 45d of the split prism 45, so the infrared light emitted from the horizontal slit index 46 is separated into two directions, upper and lower, and passes through the two holes 47b of the four-hole diaphragm 47. , 47d, and is then imaged by the imaging lens 36 on the focus plane P1. Here, the focus plane P1 is the retinal surface Eb of the fundus Ef, as in the previous embodiment.
The focal plane P2 is conjugate with the infrared reflective layer Ec of the retina Ea.

Therefore, the distance between the horizontal slit index 46 and the vertical slit index 44 and the split prism are adjusted such that the visible light index and the infrared light index are respectively imaged on two different conjugate planes Eb and Ec of the retina Ea. 45
two pairs of elements 45a, 45c and 45b,
All that is required is to determine the prism angle of 45d.

As another example, after removing the visible light cut filter of the target projection optical system for focusing from the optical path, the target projection optical unit projects the target so that the target imaging plane coincides with the focusing plane P2 that is conjugate with the retinal surface Eb. It may also be moved along the optical system. To attach and detach the visible light cut filter of the focus index projection optical system,
It may be done by a solenoid or manually, but it will be even more convenient if it is linked to the attachment and detachment of the visible light cut filter of the observation illumination optical system.

As explained above, according to the fundus camera according to the present invention, in a fundus camera that can switch between mydriatic imaging and non-mydriatic imaging, the focusing index can be set to either mydriatic or non-mydriatic. Since it can be used easily, no skill is required for focusing, and anyone can focus accurately and quickly.

[Brief explanation of the drawing]

Figure 1 is an optical layout diagram of a conventional fundus camera, Figure 2
The figure is a front view of the ring slit, Figures 3a and b are explanatory diagrams of the focusing index on the TV monitor, and Figure 4 is a front view of the ring slit.
The figure is an optical layout diagram of the focusing target projection optical system, Figures 5a, b, and c are front views of the members used in Figure 4, and Figures 6 and below are examples of the fundus camera according to the present invention. 6 is an optical layout diagram of the first embodiment, FIG. 7 is an enlarged view of the retina of the eye to be examined, FIG. 8 is an optical layout diagram of the second embodiment, and FIG. 9 is a diagram of the third embodiment. Example optical layout diagrams, Figure 10 a, b, c, Figure 11
FIG. 12 is a front view of the member of FIG. 9. 1 is an objective lens, 4 is a film, 5 is a flip-up mirror, 6 is a perforated mirror, 8 is a bar mirror, 1
0, 40, 43 are visible light cut filters, 11 is an index photographing section, 15 is a ring slit, 18 is a photographing light source, 21 is an observation light source, 27 is a monitor television, 3
0 is an index light source, 31 is an aperture stop, 32 is a condenser lens, 33 and 45 are split prisms, 3
4 is an index plate, 35 is a two-hole diaphragm, 36 is an imaging lens, 42 is a dichroic mirror, 44 is a vertical slit index, 46 is a horizontal slit index, and 47 is a 4
It is a hole drawing.

Claims (1)

[Scope of Claims] 1. It is possible to switch between both mydriatic photography and non-mydriatic photography, using visible light for the mydriatic photography and infrared light for the non-mydriatic photography; A fundus oculi characterized by comprising a common index projection optical system for focusing, and a correction means for correcting defocus caused by a difference in reflective layer in the fundus retina due to a wavelength difference between visible light and infrared light. camera. 2. The fundus camera according to claim 1, wherein a visible light cut filter is detachably inserted into the focusing target projection optical system as the correction means. 3. The fundus camera according to claim 1, wherein a plurality of light sources are provided in the focusing target projection optical system to project visible light and infrared light targets separately. 4. Claim 1, wherein the focusing target projection optical system is provided with two indices each made of different types of filters, one for transmitting visible light and reflecting infrared light and the other for reflecting visible light and transmitting infrared light. Fundus camera as described in section. 5. The focusing target projection optical system is provided with a plurality of combination means for separating light beams in mutually opposite directions, and a target is arranged in correspondence with each of these combination means. Fundus camera as described in section. 6. Claim 5, further comprising means for separating the wavelengths of the light beams passing through the combination means.
Fundus camera as described in section. 7. The fundus camera according to claim 5, wherein the indices corresponding to the combination means are arranged at different positions.