JPS60207636A - Eyeground camera - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides i! The present invention relates to a fundus camera that performs observation photography, has a built-in index projection optical system for focusing, and is switchable between mydriatic photography and non-mydriatic photography.

Conventionally, focusing of a fundus camera is generally performed by an observer looking through an observation eyepiece and finely adjusting a focus lens behind the objective lens. However, it is necessary to match the aerial image of the eye fundus to the cross to focus at 7.
> The conventional method of adjusting images requires skill, and in cases such as mass medical examinations, it fatigues the observer and results in a color-based image. 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. In order to solve this problem, a device that projects a focusing index onto the fundus of the eye has recently been developed, and an application has already been filed by the present applicant.

The outline of this apparatus will be explained below with reference to FIGS. 1 to 5.

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 includes an objective lens 1 located in front of the eye E to be examined and a focus lens 2 following it.
, a photographic lens 3, and a film 4, and a flip-up mirror 5 is movably interposed between the photographic lens 3 and the film 4. Further, a perforated mirror 6 is installed diagonally between the objective lens l and the focus lens 2, and a bar mirror 8 whose tip is a reflective surface is placed in the fundus illumination optical path on the entrance side following the relay lens 7. and this bar mirror 8
can be moved out of the optical path by a solenoid 9. On the incident side of the rod mirror 8, an index projection section 11 for focusing is arranged next to the visible light cut filter 10. The target projection optical system consisting of these 8 to 11 members is mounted on a base plate 12, and this base plate 12 is movable in the optical axis direction of the fundus illumination optical path, and is moved by an interlocking mechanism 13. It is displaced while maintaining a constant relationship with the focus lens 2.

In a state where the bar mirror 8 is removed from the optical path.

The fundus illumination optical system includes a relay lens 7, a relay lens 14, and a ring slit 15 as shown in FIG.
．． A reflecting mirror 16, a condenser lens 17, a photography light source 18 consisting of a strobe tube, a removable visible light cut filter 19, a condenser lens 20, and an observation light source 21 consisting of a tungsten lamp are arranged. In addition, 22
indicates a reflector of the observation light source 21.

On the other hand, on the reflection side of the flip-up mirror 5, following the field lens 23, an optical path switching mirror 24 and a television lens 25 are provided.
, infrared imaging tubes 26 are arranged one after another, and the output of the infrared imaging tubes 26 is displayed on a television monitor 27. Further, a direct viewing lens 28 is disposed on the optical path switched by the mirror 24, so that the fundus image can be directly observed by the examiner's eye e.

When observing mokoyana with this fundus camera, the observation light source 2
The emitted light passes through a condenser lens 20 and a visible light cut filter 19, and is converted into infrared light.

After the light is focused on the photographing light source 18, the ring slit 15 is illuminated by the condenser lens 17. Further, the infrared light emitted from the ring slit 15 is imaged on the perforated mirror 6]- by the relay lens 14.7, and then re-imaged near the erythema of the eye E by the objective lens l, and is then reimaged in the vicinity of the erythema of the eye E to be examined. to illuminate. The light reflected from the fundus Ef passes through the objective lens L, the perforated mirror 6°, the focus lens 2, and the photographic lens 3.
After forming an image on the field lens 23 by the second mirror 5, the image is formed on the infrared imaging tube 26 by the mirror 24 and the television lens 25, and is displayed as a monochrome visible light image on the television monitor 27.

In the illumination light flux, as described above, the base plate 12 which moves in the direction of the fundus illumination optical axis while maintaining a constant relationship with the focus lens 2 is connected by the interlocking mechanism 13.
When the focus plane of the index projection unit 11 placed above, the fundus Ef of the eye E to be examined, and the film 4 are in a conjugate relationship position, the index A is projected onto the television monitor as shown in FIG. 3(a). It becomes a straight line on 27.

However, the human retina has different reflective layers or depths for infrared light and visible light, so observation and focusing are done using infrared light and visible light.
When photographing using visible light, it is necessary to perform focus correction for infrared light and visible light in advance. This corrected focusing index light flux enters the fundus illumination light flux from the index projection unit 11 through the Hayashi mirror 8, passes through the relay lens 7, the perforated mirror 6, and the objective lens l, 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. 3(b) 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.

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

In addition, the observation light source 21 is turned on and the visible light cant filter 19 is turned on.
is removed from the optical path, and the light reflected from the flip-up mirror 5 is
By rotating the optical path switching mirror 24 and guiding it to the direct viewing lens 28, the fundus Ef can be directly observed using visible light. However, in this case, there is a visible light cut filter in the index photographing optical system.
The focusing index cannot be used because it contains 0 and because the index projection optical system performs focus correction for infrared light and visible light.

As shown in FIG. 4, the index projection unit 11 sequentially connects an index light source 30 consisting of a tungsten lamp to an aperture stop 31;
It is composed of 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 31, index plate 34, and two-hole diaphragm 35 are shown in FIG. 5(a), respectively. It has slits or holes shaped as shown in (b) and (c).

Here, the light from the index light source 30 passes through the aperture diaphragm 31 and illuminates the split prism 33 by the condenser lens 32. The index plate 34 placed near the split prism 33 is a slit-shaped aperture stop as shown in FIG. Later, an image is formed by the imaging lens 36 onto the Hayashi mirror 8 via the visible light cant filter IO. If the reflection position of this Hayashi mirror 8 is conjugate with the fundus Ef, then
The light from the index plate 34 passes through the relay lens 7, is reflected by the perforated mirror 6, and then passes through the objective lens l to the fundus Ef.
The image is formed in a straight line without being split upwards.

Since the photographing light from the photographing light source 18 is visible light, the fundus E
While the light is reflected on the retinal surface of f, since the focusing index is infrared light, it is reflected on 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 conjugate, 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 are 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 main purpose of this camera is to enable switching between mydriatic and non-mydriatic imaging, incorporate an index projection optical system for focusing, and use both visible light and non-mydriatic imaging. The present invention is characterized in that it includes a correction means for correcting out-of-focus due to a difference in wavelength of infrared light.

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 in FIG. 1, and numerals 30 to 36 are the same as in FIG. - 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.

Here, the focus plane P2 in the absence of the visible light cut filter 40 is conjugate with the retinal surface Eb of the subject's eye E shown in FIG. In addition, visible light is cut so that the focus plane P1 when the visible light cant filter 40 is inserted is conjugate with the infrared light reflecting layer Ec located at a position deeper than the retinal surface Eb by the thickness of the retina Ea. By simply selecting the thickness of the filter 40 and moving the visible light cut filter 40 in and out using the solenoid 41, it is possible to correct out of focus due to the wavelength difference between infrared light and visible light. Note that, in view of the amount of correction, the dummy glass may be inserted after the visible light cut filter 40 is removed.

FIG. 8 shows a second embodiment, in which a dichroic mirror 42 that reflects infrared light and transmits 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 an infrared light path from the second index light source 30b to the index plate 34b.
Two visible light paths are provided.

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 and a split prism 33a.
, is divided through the index plate 34a, is reflected by the dichroic mirror 42, passes through the two-hole diaphragm 35 and the imaging lens 36, and is imaged on the focus plane P1 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 passes through the split prism 33b and the index plate 34b, is separated, passes through the dichroic mirror 42, and passes through the dichroic mirror 42. The light passes through the aperture 35 and the imaging lens 36 and is imaged onto a focal plane P2 that is conjugate with the retinal surface Eb of the fundus Ef.

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 for visible light and infrared light are always projected. Here, the aperture diaphragm 31 has the shape shown in FIG. The vertical slit index 44 shown in FIG. 10(b) is made of visible light transmitting/infrared light reflecting filters before and after the split prism 45, and the vertical slit index 44 shown in FIG. A horizontal slit indicator 46 shown in (c) is arranged. Also, split prism 45 is also $l
As shown in FIG. 1, elements 45a and 45c, and elements 45b and 45d are paired at 180 degrees. Furthermore, in front of the imaging lens 36, 46 apertures 47 as shown in FIG.
They are paired in the 0 degree direction.

In FIG. 9, light emitted from an index light 830 passes through an aperture stop 31 and illuminates a vertical slit index 44 that transmits visible light and reflects infrared light through a condenser lens 32. The light is transmitted through a pair of split prisms 45a and 45c.
After the light is separated into two directions by the diaphragm 47, the light passes through the two holes 47a and 47c of the four-hole diaphragm 47 and is imaged by the imaging lens 36 on the focus plane P2. 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. Immediately before entering the horizontal slit index 46, the elements 45b and 4 of the sprint prism 45
5d, the infrared light emitted from the horizontal slit index 46 is separated into two directions, the upper and lower directions, and the infrared light passes through the two holes 47b of the four-hole diaphragm 47.
, 47d, the light is imaged on the focus plane PI by the imaging lens 36. Here, the focus plane PI is conjugate with the retinal surface Eb of the fundus Ef, as in the previous embodiment, and the focus plane P2 is conjugate with the infrared reflective layer Ec of the retina E8.

Therefore, the interval between the horizontal slit index 4G and the vertical slit index 44, and the distance between the split prism 45 and the split prism 45 are adjusted so that the visible light index and the infrared light index are respectively focused on two different conjugate planes Eb and Ec of the retina Ea. 2 pairs of elements 4
It is only necessary to determine the prism angles of 5a, 45c, 45b, and 45d.

As another example, after removing the visible light cut filter of the focusing target projection optical system from the optical path, the target projection optical section is indexed 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 projection optical system. The visible light cut filter of the focus indicator projection optical system may be attached and detached by a solenoid or manually, but it will be 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 and non-mydriatic imaging, the focusing index can be used for either mydriatic or non-mydriatic imaging, so no one needs to be skilled at focusing. This has the effect of being able to focus accurately and quickly even when the camera is in use.

[Brief explanation of the drawing]

Figure 1 is a diagram of the optical layout of a conventional fundus camera, Figure 2 is a front view of the Ringes Lint, Figures 3 (a) and (b) are illustrations of focusing indicators on a television monitor, and Figure 4 is an illustration of focusing. Optical layout diagram of the target projection optical system, Fig. 5(a)
, (b), and (c) are front views of the members used in FIG. 4, and FIG. 6 and the following show embodiments of the fundus camera according to the present invention. Layout, No. 7
The figure is an enlarged view of the retina of the subject's eye, Figure 8 is an optical layout diagram of the second embodiment, Figure 9 is an optical layout diagram of the third embodiment, and Figures 1O (a), (b), (c) ), FIGS. 11 and 12 are front views of the member shown in FIG. 9. Symbol l is the objective lens, 4 is the film, 5 is the flip-up mirror, 6 is the perforated mirror, 8 is the rod mirror, 10.40.43
11 is a visible light cut filter, 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 TV, 30 is an index light source, 31 is an aperture stop, 3
2 is a condenser lens, 33.45 is a split prism, 34 is an index plate, 35 is a two-hole diaphragm, 36 is an imaging lens, 42 is a tie black mirror, 44 is a vertical slider)
The indicator 46 is a horizontal slit indicator, and 47 is a four-hole aperture. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] ■: It is possible to switch between both mydriatic photography and non-mydriatic photography, and it has a built-in index projection optical system for focusing, which prevents focus deviation due to the wavelength difference between visible light and infrared light. A fundus camera characterized by having a correction means for correction. 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. The focusing index projection optical system is provided with two indexes each made of different types of filters, one for transmitting visible light and reflecting infrared light, and one for reflecting visible light and transmitting infrared light. The fundus camera according to item 1. 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. The fundus camera according to item 4. 6. The fundus camera according to claim 5, further comprising means for separating the wavelengths of the light beams passing through the combination means. 7. The fundus camera according to claim 5, wherein the indices corresponding to the combination means are arranged at different positions.