JPS6254497B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ophthalmological apparatus such as an ophthalmoscope or a fundus camera.

When observing and photographing a subject's eye with an ophthalmological device, it may be necessary to enlarge a part of the fundus for detailed diagnosis. Particularly as screens become wider these days, the need for magnification increases because the imaging magnification decreases if the film size used in the fundus camera is kept constant.

Here, a fundus camera that stabilized the amount of photographing light regardless of changes in photographic magnification was published in Japanese Patent Application Laid-Open No. 51-79352.
It is known from the publication No.

However, in Japanese Patent Application Laid-Open No. 51-79352, in order to provide a photographing diaphragm at a position optically conjugate with the perforated mirror in the photographing optical path, it is necessary to extend the lens system in the optical axis direction, making it difficult to make the device more compact. Can not.

In Japanese Unexamined Patent Publication No. 51-79352, the amount of illumination light applied to the eye to be examined is constant, and it is not possible to deal with phototoxicity caused by irradiating the eye to be examined with unnecessary light.

An object of the present invention is to provide an ophthalmologic apparatus that eliminates the above-mentioned conventional problems.

Before describing embodiments of the present invention, a reference example using a filter as a light amount adjusting means will be described below. In FIG. 1, E is the eye to be examined and Ef is the fundus. On the other hand, 1
1 is an observation lamp, 2 is a condenser lens, 3 is a photography strobe tube, 4 is a second condenser lens, 5 is an optical path refracting mirror, 6 is a filter whose density changes sequentially, and 7 is a slit plate with an annular aperture. . The planar configuration of the filter 6 and the slit plate 7 is as shown in FIG. 2, and as the filter 6 is moved, the amount of light passing through the opening of the slit plate changes. Further, the luminous flux emitted from the lamp 1 and the luminous flux emitted from the strobe tube 3 converge on the slit plate 7.

8 and 9 are relay lenses, 10 is a perforated mirror with an aperture, and 11 is an objective lens.
The aforementioned slit plate 7 is conjugate with respect to the relay lenses 8 and 9, and the aperture mirror 10 and the pupil of the eye to be examined occupying a predetermined position are conjugate with respect to the objective lens 11. 12 is an imaging lens, 13 is a film, and F is an image plane of the imaging lens.
The image is re-imaged on the film 13 by.

14 is a flip mirror, 15 is a field lens, 1
6 is an optical path refractor, 17 is an eyepiece, and 18 is an observer. Further, F' is the image plane (observation image plane) of the imaging lens via the flip-up mirror 14.

The imaging lens 12 is a variable magnification lens, 12a and 12b are movable in the optical axis direction, 12a is a so-called variator, and 12b is a concerter. Reference numeral 20 denotes a cam tube, and pins connected to lenses 12a and 12b are engaged with respective cam grooves cut in the cam tube. Note that the linear cam tube in the optical axis direction, which the pin separately engages with, is omitted. 21 is a gear portion formed around the cam tube; 22 is a small gear meshing with the gear portion; the small gear 22 is driven by a drive portion 24; 25 is easy and density filter 6
The pinion 26 is connected to the pinion 26 and is engaged with the rack, and the pinion 26 is driven by the drive section 24. At that time, operate the drive unit 24 to
0, the lenses 12a and 12b move, and the focal length of the imaging lens 12 changes.As a result, the density filter 6 moves in response to the change in the observation or imaging light flux that has passed through the annular aperture at the fundus Ef. The configuration is such that when the light is reflected, passes through the objective lens 1 and the imaging lens 12, and enters the film surface 13 or the image surface F', the amount of light on the surface is constant. Note that as the magnification of the imaging lens 12 increases,
The high transmittance portion of the density filter 6 overlaps the slit plate 7, and the amount of transmitted light increases.

Next, the effect will be explained. When the lamp 1 is turned on, the light beam emitted from the lamp 1 converges at the condenser lens 2, diverges, converges again at the condenser lens 4, changes direction at the mirror 5, enters the density filter 6, and becomes the focal point of the imaging lens 12. The light transmittance is adjusted according to the distance. Then, it passes through the annular opening of the slit plate 7, and by the action of the relay lenses 8 and 9, the perforated mirror 1
After the image is once formed on 0, the fundus Ef is illuminated with an illumination light beam having a fixed angle of view through the objective lens 1. The object light reflected by the fundus Ef passes through the objective lens 1 and the imaging lens 12.
After being reflected by the flip-up mirror 14, an image of the fundus is formed on the observation image plane F', and the field lens 15 and mirror 16
and is observed by the observer through the eyepiece lens 17. From now on, if the observer wishes to have an enlarged view of the observation area using Figure 3 as the observation field, the drive unit 24
When the cam tube 20 is operated, the cam tube 20 rotates and the lens 12
a and 12b are guided to the cam groove, and the imaging lens 12
As the focal length of the density filter 6 increases,
moves, and the amount of transmitted light increases. Therefore, the observer observes the enlarged field of view depicted in FIG. 4, and the brightness of the field of view does not change. Next, the flip-up mirror 14
When the strobe tube 3 is raised to emit light, the amount of strobe light is also adjusted, so that the film 13 is exposed with the appropriate amount of exposure.

FIG. 5 depicts another example of a density-varying filter, in which the density changes in several stages. In this case, the filter 6 is assumed to be moved intermittently, and the focal length of the imaging lens 12 is also configured to take a certain value in stages.

Another configuration for changing the magnification of the optical system interposed between the eye to be examined and the observation/photographing plane will be explained below with reference to FIGS. 6 to 10. Note that the figure is a partial view, and the same members as those in FIG. 1 are given the same numbers.
In FIG. 6, the entire imaging lens 12 is configured to be replaceable with a convergent lens 30 having a different focal length. However, when the interchangeable lens 30 is attached, the object plane of this lens coincides with the image plane P of the objective lens 11, and the image plane coincides with the film plane 13.

In FIG. 7, a part of the imaging lens 12 is replaced. For example, the imaging lens 12 is composed of a fixed front group 12a and a detachable rear group 12b, and the rear group 12b is replaced with a lens group 31 having a different focal length. Change the composite magnification by exchanging with .

FIG. 8 shows a configuration in which a lens is installed in the photographing optical path to change the combined focal length of the optical system. FIG. 8A shows the configuration before the lens is attached, and FIG. 8B shows the configuration when the diverging lens 32 is inserted. However, although the focal length of the optical system increases by inserting the lens 32, the position of the image plane also moves backward. On the other hand, as shown in Figure 1, methods for adjusting the focus of a fundus camera generally include moving part or all of the imaging lens in the optical axis direction and changing the distance between the imaging lens and the flip-up mirror. However, in the case of a configuration in which a variable magnification lens 32 is attached as shown in FIG. Film side 1
You can easily deal with this by moving position 3.

9A and 9B depict an example of inserting a variable magnification lens 33 consisting of at least two groups to change the magnification without changing the image plane position, A shows before insertion, and B shows after insertion. Indicates the form. In Figure 9B, a variable magnification lens is inserted behind the imaging lens.
FIG. 0 shows an example in which a variable power lens 34 is inserted just in front of the imaging lens.

In the above example, the magnification can be changed in two steps, but it is possible to change the magnification in more steps by providing interchangeable lenses or variable magnification lenses with various focal lengths. Also, objective lens 1
1 may be replaced with another objective lens. Now, FIG. 11 shows an embodiment of the present invention.

FIG. 11 shows a configuration in which the cross-sectional area of the annular opening of the slit plate is changed to change the amount of light incident on the fundus in conjunction with the variable power of the optical system. 40 is a rotating plate,
41 is a rotation axis. Further, as shown in FIG. 12, the rotating plate 40 has annular openings 40 each having a different cross-sectional area.
a, 40b, 40d and 40c,
Predetermined annular apertures are configured to be inserted into the optical path in conjunction with the zooming of the imaging lens 12.

According to the present invention described above, the brightness of the visual field is maintained constant even when the observation region is enlarged by changing the magnification of the imaging/observation optical system.

Furthermore, in the present invention, since the light adjusting means is provided in the optical path within the illumination system, an excessive amount of light does not enter the eye compared to a case where the light adjusting means is provided in the optical path within the observation photographing system.

In addition, in the present invention, the annular aperture itself can be changed at a position that is optically approximately conjugate with the perforated mirror, that is, at a position where there is sufficient space, and the device can be made more compact.
Keep it simple.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing a reference example, Figure 2 is a plan view showing one part of the reference example, Figures 3 and 4 are views showing the observation field of view, and Figure 5 is another view of the density change filter. Plan views showing examples, Fig. 6, Fig. 7, Fig. 8A,
B, FIGS. 9A, B, and 10 are sectional views showing the configuration for changing the magnification of the optical system, FIG. 11 is a sectional view showing an embodiment of the present invention, and FIG. 12 is a part of the structure. In the figure, 6 is a density change filter, 12 is an imaging lens, 12a and 12b are movable lens elements, 20 is a cam tube, 21 is a gear part, 22 is a small gear, 24 is a drive part, and 25 is a The rack and 26 are pinions.

Claims (1)

[Claims] 1. In order from the side of the eye to be examined, an objective optical system, a perforated mirror that is optically approximately conjugate with the anterior segment of the eye to be examined, and an annular aperture that is optically approximately conjugate with the perforated mirror regarding the objective optical system. system, and a variable magnification optical system that images a predetermined part of the eye to be examined illuminated by the illumination system on a predetermined imaging plane through the objective optical system and the aperture of the perforated mirror. An ophthalmological apparatus having an observation system, characterized in that the apparatus includes means for changing the cross-sectional area of the annular aperture according to a change in magnification of the variable magnification optical system so that the amount of light reaching the image forming surface is substantially constant. Ophthalmology equipment.