JPS6041949A - 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.

An embodiment of the present invention will be described below. In FIG. 1, E is the eye to be examined and Ef is the fundus. On the other hand, 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 arm, 6 is a filter whose density changes sequentially, and 7 is a slit with an annular aperture. It is a board. The planar configuration of the filter 6 and the slit plate 7 is as shown in Figure @2, and when the filter 6 is moved, the amount of light passing through the slit plate bottom opening 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, 1o is a perforated mirror with an aperture, and 11 is an objective lens, which is conjugate with respect to the perforated mirror 10 and the aforementioned 7-slit plate 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. An image of the fundus Ef is formed by the objective lens 11, and then re-imaged on the film 13 by the imaging lens 12. .

14 is a flip-up 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, and includes 12a and 121).
is movable in the optical axis direction, 12a is a so-called variator, and 12b is a concerter. 2o is a cam tube, and pins connected to lenses 12a and 12b are engaged with each of the 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 that meshes with the gear portion; the small gear 22 is driven by a drive portion 24; A rack 25 is connected to the density filter 6, a pinion 26 meshes with the rack, and the pinion 26 is driven by the drive unit 24. At that time, the drive unit 24 is operated to rotate the cam tube 2o, and the lens element 2a is rotated.
12b moves and the focal length of the imaging lens 12 changes, and as a result, the density filter 6 moves, and as a result, the observation or photographing light flux that has passed through the annular aperture is reflected by the fundus Ef, and the objective lens 1 is focused. The configuration is such that when the light passes through the image 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, a portion of the density filter 6 with high transmittance overlaps with 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, then is converged again at the condenser lens 4, changes its 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. Next, the object light passes through the annular aperture of the slit plate 7 and is reflected by the relay lenses 8 and 9. The object light passes through the objective lens, the lens 1, and the imaging lens 12, and is reflected by the flip-up mirror 14. An image is formed and observed by an observer through a field lens 15, a mirror 16, and an eyepiece 17. From now on, if the observer wishes to have an enlarged view of the observation area using Figure 3 as the observation field, by operating the drive unit 24, the cam v20 will rotate and the lens 1
2a and 12b are guided to the cam groove, and as the focal length of the imaging lens 12 increases, the density filter 6 also 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. Then flip mirror 1
4 and causes the strobe tube 3 to emit light, the amount of strobe light is adjusted and the film 13 is exposed at the proper side sight.

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 values that vary stepwise.

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 3o 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. 8 (2) shows the configuration before the lens is attached, and FIG. 8 (C) 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 () in Fig. 8, if it is adopted in a fundus camera with a structure in which the distance between the imaging lens and the flip-up mirror is changed, the position of the image plane can be moved. This problem can be easily solved by moving the position of the film surface 13.

9 (5) and (13) 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 (8) shows the state before insertion, (c) shows the configuration after insertion. FIG. 9(b) shows an example in which a variable magnification lens is inserted behind the imaging lens, and FIG. 10 shows an example in which a variable magnification 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.

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, and 41 is a rotating shaft.

Further, as shown in FIG. 12, the rotary plate 40 is provided with annular openings 40a, 40b, 40d, and 40c each having a different cross-sectional area. It is configured to be inserted into the optical path.

FIG. 13 shows an example of changing the amount of illumination light using a polarizing plate. In the figure, the means disposed between relay lenses 8 and 9 consists of an analyzer 41 and a polarizer 42, and if either the analyzer 41 or the polarizer 42 is rotated around the optical axis, The amount of light that passes through changes. Therefore, the imaging lens 1
If the relative rotation angle between the analyzer and the polarizer is changed in accordance with the magnification change of 2, the amount of light on the image plane becomes constant.

FIG. 14 shows an example of changing the amount of illumination light by applying the Kerr cell effect.

41 is an analyzer, and 42 is a polarizer, both of which are fixed.

43 is a car cell, and 43a and 43b are power supply terminals. When the voltage applied to the power supply terminals 43a and 43b is changed, the transmittance of the light control means including the analyzer, the cell, and the polarizer changes. Therefore, the voltage applied to the Kerr cell is changed in conjunction with the zooming of the imaging lens 12.

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 photographing/observation optical system, so the light amount can be adjusted repeatedly according to the change in magnification. This frees you from trouble and has the effect of eliminating inconveniences such as forgetting to adjust the photographing light source and taking photographs with insufficient exposure.

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.

Furthermore, in the present invention, since the eye to be examined is illuminated at a constant angle of view, even if the photographing range of the patient part changes due to changes in the magnification of the variable magnification optical system, a wide-angle view of the patient part including the non-photographing area can be obtained. Observation can be performed at all times, and the observation area can be set larger than the imaging area to produce great effects.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a plan view showing a part of the embodiment, Figs. 3 and 4 are views showing the observation field, and Fig. 5 is a density change filter. 6, 7, 8 (8)), and 9 (5).
) 0 and FIG. 10 are cross-sectional views showing the configuration for changing the magnification of the optical system, FIG. 11 is a cross-sectional view showing other embodiments, FIG. 12 is a plan view showing one of the members, and FIG. 14 and 14 are cross-sectional views showing different embodiments, in which 6 is a density change filter, 12 is an imaging lens, 12a and 12
b is a movable lens element, 20 is a cam tube, 21 is a gear portion, 22 is a small gear, 24 is a drive portion, 25 is a rack, 26
is a binion.

Claims (1)

[Scope of Claims] An illumination system that illuminates the eye to be examined at a constant angle of view, and a variable magnification optical system that images a predetermined part of the eye that is illuminated by the illumination system on a photographing surface or an observation surface with variable magnification. and an ophthalmological apparatus having an observation system for observing an observation surface, wherein a light adjustment means for regulating the amount of light passing through is provided in the optical path in the illumination system, and the light adjusting means for regulating the amount of light passing through is provided in the optical path of the illumination system, and the light adjusting means is provided in the optical path in the illumination system, and An ophthalmological apparatus characterized in that the amount of light passing through the light adjusting means is changed in order to substantially constant the amount of light that is reflected at the imaging surface or the observation surface.