JPS6041948A - Ophthalmic apparatus - 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 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 as the imaging magnification decreases if the film size used in the fundus camera is kept constant.

The present invention integrates the means for changing the magnification of the optical system and the means for changing the light amount, thereby saving the effort of adjusting the light amount and eliminating fluctuations in screen brightness that occur due to changes in the magnification. purpose.

Before describing one embodiment of the present invention, a fundus camera to which the present invention is applied will be described below. In FIG. 1, E is the eye to be examined and Ef is the fundus. On the other hand, 2 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, and 7 is a slit plate having an annular opening. Here, the light beam emitted from the lamp 1 and the light beam 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 aperture, 11 is an objective lens, the perforated mirror 10 and the slit plate 7 mentioned above are conjugate with respect to the relay lenses 8 and 9, The pupil of the eye to be examined, which occupies a predetermined position, is the objective lens 11.
is conjugate with respect to 12 is an imaging lens, 13 is a film, and F is an image plane of the imaging lens ll, in which the image of the fundus Ef is formed by the objective lens 11, and the imaging lens 12
The image is re-imaged onto the film 13 by the following.

14 is a mirror, 15 is a field lens, 16 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 compensator. 20 is a cam tube,
Each of the cam holes cut in the cam tube engages each of the pins connected to the lenses 12a and 12b. Note that the linear cam tube in the optical axis direction, which the pin separately engages with, is omitted.

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, then is converged again at the condenser lens 4, and then changes its direction at the mirror 5. Next, the light passes through the annular opening of the slit plate 7, and after forming an image on the perforated mirror 10 by the action of the relay lenses 8 and 9, it passes through the objective lens 1 and illuminates the fundus Ef with an illumination light beam having a constant angle of view.

The object light reflected by the fundus Ef passes through the objective lens 1 and the imaging lens 12 and is reflected by the mirror 14, forms an image of the fundus on the observation image plane F, and passes through the field lens 15, mirror 16, and eyepiece 17. observed by an observer. Here, FIGS. 2 and 3 show the observation fields at wide angle and narrow angle, respectively.

Next, when the flip-up mirror 14 is raised and the strobe tube 3 emits light, the amount of strobe light is also adjusted, so that the film 13 is exposed with a proper exposure amount.

Next, with reference to FIGS. 4 to 8, another configuration for changing the magnification of the optical system interposed between the eye to be examined and the observation/photography plane will be explained. Note that the figure is a partial view, and the same members as those in FIG. 1 are given the same numbers. FIG. 4 shows the entire imaging lens 12,
It 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. 5, 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. 6 shows a configuration in which a lens is installed in the photographing optical path to change the combined focal length of the optical system. Figure 6 (A) shows the configuration before the lens is attached, and Figure 6 (B) shows the divergent lens 3.
2 is shown when 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, methods for adjusting the focus of a fundus camera as shown in Figure 1 include a method of moving part or all of the imaging lens in the optical axis direction, and a method of changing the distance between the imaging lens and the mirror. Although it is common, in the case of a configuration in which a variable magnification lens 32 is attached as shown in Fig. 6 CB), the position of the image plane can be moved if it is adopted in a fundus camera with a structure that changes the distance between the imaging lens and the flip-up mirror. However, it can be easily dealt with by moving to the position of the film surface 13.

7(A) and 7(B) depict an example in which a variable power lens 33 consisting of at least two groups is inserted to change the magnification without changing the image plane position, and FIG. 7(A) shows the state before insertion; CB)
indicates the configuration after insertion. In FIG. 7(B), the variable power lens is inserted behind the imaging lens, whereas FIG. 8 shows an example in which the variable power lens 34 is inserted just in front of the imaging lens.

Although the above example shows an example in which the magnification can be changed in two steps, it is possible to change the magnification in more steps by preparing interchangeable lenses or variable magnification lenses with various focal lengths. Furthermore, the objective lens 11 may be replaced with another objective lens.

Next, the present invention for making the amount of light on the image plane constant will be explained in detail. FIGS. 9, 10, and 11 show a configuration in which the amount of light on the image plane is made constant by changing the amount of light from the light emitting source. The driving unit 24 in FIG. 9 changes the focal length of the imaging lens 12 by a zoom method, a lens exchange method, or a variable power lens mounting method, and also changes the amount of light of the strobe and observation illumination. Figure 10 shows an outline of a configuration that changes the amount of strobe light emission by changing the capacity of the capacitor.The number of capacitors 〇 is changed and multiple sets are connected in parallel, and the contact SL is set by changing the number of capacitors 〇.
, S2, and S3 are selected and arranged to be charged. 35 is a trigger switch, and when this switch is turned on, the strobe tube 3 emits a selected amount of light. FIG. 11 shows a configuration example for changing the amount of light from the observation lamp 1, in which the lamp 1 and the variable resistor 36 are connected in series to a power source, and the resistance value is switched in, for example, three levels to change the amount of light emitted.

Therefore, when the magnification of the imaging lens shown in FIG. 9 is changed, the switch shown in FIG. Nevertheless, the amount of light on the image plane or observation image plane remains constant during observation or photography.

According to the present invention described above, the brightness of the field of view is maintained constant even when the observation area is enlarged by changing the magnification of the imaging/observation optical system, so the light amount can be adjusted according to the change in magnification. It has the effect of freeing you from repeated troubles and eliminating inconveniences such as forgetting to adjust the photographing light source and taking photographs with insufficient exposure. Furthermore, the present invention has the effect of eliminating the need for mechanically moving the light adjusting member.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a configuration example of a fundus camera to which the present invention is applied;
Figures 2 and 3 are diagrams showing the observation field of view, Figures 4 and 5,
6(A)(B), FIG. 7(A)(B), and FIG. 8 are cross-sectional views showing the configuration for changing the magnification of the optical system, respectively;
FIG. 9 is a sectional view showing an embodiment of the present invention, FIG. 1O is an electric circuit diagram showing a configuration for changing the amount of strobe light, and FIG.
The figure is an electric circuit diagram showing a configuration for changing the light amount of the observation lamp.

Claims (1)

[Scope of Claims] An illumination system including a light source that illuminates the eye to be examined, and a variable magnification optical system that images a predetermined part of the eye illuminated by the illumination system on a photographing surface or an observation surface with variable magnification. In the ophthalmological apparatus, means for changing the amount of light emitted from the light source in conjunction with a change in magnification of the variable magnification optical system in order to substantially constant the amount of light that is reflected by the subject area and reaches the photographing surface or the observation surface. An ophthalmological device characterized by having the following.