JPS6122966B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fundus camera for performing general photography and fluorescent fundus photography.

Fluorescence fundus photography is a type of fundus photography in which the fundus is illuminated with excitation light with a wavelength near blue, timing the time when frioretsen sodium, etc. injected through the cubital vein reaches the fundus circulation system, and the fluorescence is removed from the blood column. It is performed by generating light and illuminating only the fluorescent light from among the reflected light from the eye to be examined. At that time, a barrier filter is installed in the photographic optical path and an exciter is installed in the photographic optical path to separate the wavelengths, so the amount of light decreases depending on the transmission characteristics of the filter, and the fluorescence generated in the fundus of the eye decreases. Since the light emission rate is quite low, a larger amount of illumination light is required compared to general color photography.

On the other hand, in a fundus camera in which the imaging system and illumination system are arranged coaxially, a sunspot is provided in the illumination optical path to prevent part of the illumination system from reflecting off the cornea and entering the imaging system. A method of blocking reflected light in advance has been practiced for a long time. However, recently,
As objective lenses became wider (45 degrees), harmful light reflected by the crystalline lens became a problem. This is because with a conventional narrow-angle retinal camera (30°), the sunspot shadow, or image, covered not only the reflective area of the cornea but also the crystalline lens. This is because the shadow is shortened and harmful light is also generated in the crystalline lens.

As a countermeasure, Japanese Patent Publication No. 51-24249 removes the light reflected by the lens surface by forming a sunspot image on the front surface or between the front and back surfaces of the crystalline lens, and Japanese Utility Model Publication No. 1971-107140 removes the reflected light from the lens surface. A conjugate sunspot is provided in the illumination system to eliminate light scattered within the lens and by the posterior surface of the lens.

By the way, forming a sunspot image within the subject's eye means that the amount of illumination light decreases accordingly, which is inconvenient for fluorescence fundus photography.

An object of the present invention is to increase the amount of illumination light when performing fluorescence photography.

An embodiment will be described below with reference to the drawings.

In Figure 1, E is the eye to be examined, E _f is the fundus, and E _p is the pupil.
E _c is the crystalline lens, and R is the posterior surface of the crystalline lens. Further, 1 is a wide-angle objective range, 2 is an imaging lens, 3 is a photosensitive film, and 4 is an aperture stop, and these members 1 to 4 constitute a photographing system. Next, 5 is a quick return mirror, 6 is an optical path bending mirror, 7 is an eyepiece, and the members 5 to 7 constitute a finder.

Reference numeral 9 denotes a perforated mirror having an opening 9a, which is installed obliquely with respect to the optical axis of the imaging system. 10 is a tungsten lamp for observation light source, 11 is a condenser lens, 12 is a strobe tube for photography light source, 13 is a second condenser lens, and 14 is an optical path bending mirror. Reference numeral 15 denotes a light-shielding plate having an annular slit 15a, the central light-shielding portion having the function of forming an area through which the light flux emitting from the fundus and reaching the film passes, and the outer edge of the slit controlling the diameter of the light flux for illuminating the fundus. Further, 16 is a relay lens. These members 9 to 16 and the objective lens 1 constitute an illumination system. Here, the mirror surfaces of the relay lens 16 and the perforated mirror 9, and the position conjugate with the light shielding plate 15 with respect to the objective lens 1 are configured so as to be conjugate with the aperture 4 with respect to the objective lens 1,
The position where the image of the light shielding plate 15 is formed is between the vertex of the cornea and the iris, preferably on the pupil E _p .

Next, reference numeral 17 denotes a turret that holds the exciter 19 and the transparent plate 18 to which the light-shielding point 18a is fixed, and is rotatable around a shaft 20.
It is assumed that the exciter 19 is connected to a mechanism (not shown) in order to align the center of the exciter 19 with the optical axis. The position of the light-shielding point 18a is conjugate with the mirror surface of the relay lens 19, the perforated mirror 9, and the objective lens 1, which is slightly closer to the cornea than the vertex of the posterior surface R of the crystalline lens. is also removed at the same time.
Further, in order to match the optical path length, it is preferable that the optical thicknesses of the transparent plate 18 and the exciter 19 be made the same.

Reference numeral 21 denotes a barrier filter, which can be attached or detached between the aperture 4 and the film 3. Exciters and barrier filters are well known, so I won't go into details about them, but exciters are also called excitation filters, are blue in color, and have the function of passing light in a wavelength range suitable for exciting fluorescent substances from white light. The barrier filter, also called a superfilter, is yellow in color and has the function of passing only fluorescent light from the light reflected from the fundus of the eye. The excitation wavelength range and the overwavelength range are separated from each other.

In the above configuration, in the case of general color photography, the light shielding point 18a is mounted on the optical axis of the illumination system, and when the tungsten lamp 10 is turned on, the light flux emitted from the lamp 10 is passed through the condenser lens 11 and once onto the strobe tube 12. After condensing, the light diverges, is convergently refracted by the condenser lens 13, is reflected by the mirror 14, and is condensed onto the light shielding plate 15. The annular slit 15a of the light shielding plate acts as a secondary light source, and the slit 15a acts as a secondary light source.
The light beam emitted by the light a is once converged on the perforated mirror 9a by the relay lens 16, and then reflected there, and formed by the objective lens 1 to form a clear image of the slit on the pupil E _p of the eye to be examined, and then on the fundus of the eye. Uniformly illuminate E _f .

Figure 3 depicts the state of the illumination light flux within the subject's eye, and E _f is the fundus, E _c is the crystalline lens, and R is the posterior surface of the crystalline lens, which is the same as in Figure 1, but 15' is a light shielding plate. Image 15 and image 18a' are images of the light-shielding point 18a. Also, l ₁ and l ₂ are illumination light fluxes incident on the axis, l ₃ and l ₄
is the illumination light flux incident off-axis, but as can be seen from the figure, the fundus E _f
is incident on the The light flux l ₄ is reflected and scattered across the crystalline lens E _c and the posterior surface R, and this light flux is blocked by the image 18a' of the shading point, so that harmful light is removed, and at the same time, as shown in FIG. It is inevitable that the amount of illumination light will be lower than if all the light flux were incident on the fundus.

The light beam scattered and reflected by the fundus exits from the center of the light-shielding plate image 15', and after being once imaged by the objective lens 1,
It passes through the aperture 4, is convergently refracted by the imaging lens 2, is reflected by the quick return mirror 5 to form an aerial image, is then reflected by the mirror 6, and reaches the eyepiece 7. Here, the examiner selects a position and performs focusing while checking the field of view, and after completing these adjustments, performs a release operation to turn off the lamp 10, light the strobe tube 12, and jump the mirror 5. Raise the shutter to open the shutter (not shown) and release film 3.
to expose.

On the other hand, when performing fluorescence fundus photography, the turret 7 is rotated and an exciter 19 is installed in the optical path instead of the light shielding point 18a, and a barrier filter 21 is installed in the photographing optical path. lamp 10
When the lamp is turned on, among the luminous flux emitted from the lamp 10, the luminous flux having the excitation wavelength that passes through the exciter 19 enters the pupil E.
After forming an image of the slit on _p , the fundus E _f is illuminated to excite the fluorescent substance in the blood vessels of the fundus, producing fluorescent light. At that time, as a result of the shading point 18a being removed, all of the light beams passing through the slit portion of the image 15' of the shading plate illuminate the fundus of the eye as shown in FIG. 4, so the amount of fluorescent light generated from the fundus of the eye is To increase.

Next, the fluorescent light and scattered reflected light generated in the fundus of the eye are imaged by the objective lens 1, and then pass through the diaphragm 4 and enter the barrier filter 21. Although the fluorescent light passes through the barrier filter 21, the scattered reflected light is blocked, so that only the fluorescent light is converged by the imaging lens 2 and reaches the eyepiece 7.

Note that as a result of leaving the light shielding point 18a, harmful light is generated by the crystalline lens, but since this harmful light belongs to the excitation wavelength range, it is blocked by the barrier filter 21, so that the image quality is not impaired.

When the strobe tube 12 is made to emit light, the same process as described above is followed, the mirror 5 is raised and the film 3 is exposed to fluorescent light. In this way, the light shielding object used during general photography is disabled during fluorescent photography. In addition, during general shooting, Exciter 19
The transfer of the light to the outside of the optical path and the attachment of the light shield to a predetermined position within the optical path are linked.

In the embodiment described here, it is possible to further increase the amount of light by removing the light shielding plate 15, but it should be noted that the reproduction accuracy when reattaching the light shielding plate has a greater effect on the image quality of the photograph. Should. Furthermore, although the light-transmitting plate with the light-shielding point and the exciter are exchanged using a turret, they may be attached and detached using other interlocking mechanisms, and the exciter may be attached at a different position from that of the embodiment. Note that during fluorescence photography, the light-transmitting plate provided with the light-blocking points may be moved in the direction of the optical axis to substantially nullify the light-blocking points.

The present invention as described above makes use of the unique property that the wavelengths of illumination light and photographing light differ in fluorescence photography, thereby making it possible to perform wide-angle general photography without flare, and also to provide illumination during fluorescence photography. It is an increase in light.

Fluorescence photography often requires a large number of consecutive flash shots in a short period of time, which already requires a large amount of power consumption, and wide-angle photography requires a greater amount of illumination light than narrow-angle photography. In contrast, the present invention, which can increase the amount of light for illuminating the fundus without increasing the amount of light emitted from the light source, has extremely excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention. Figure 2 is a plan view of the turret. Figures 3 and 4 are diagrams depicting the inside of the subject's eye. In the figure, 1...objective lens, 2...imaging lens,
10...Light source for observation, 12...Light source for photography, 17
...turret, 18...shading point, 19...exciter, 21...barrier filter.

Claims (1)

[Scope of Claims] 1. A shared fundus camera that is equipped with a fundus illumination system and a fundus photography system and is capable of not only general photography but also fluorescence photography in which fundus illumination light and fundus photography light are wavelength-separated. a ring slit provided at a position optically conjugate with the eye; a light shield provided near the ring slit in a fundus illumination system during general imaging to remove harmful light from the anterior segment of the subject's eye; and a fluorescent material. A shared fundus camera comprising means for disabling a function of the light shielding object for removing harmful light in the anterior segment of the subject's eye during photographing. 2. The scope of claim 1, wherein the movement of an exciter filter provided in a fundus illumination system for fluorescence imaging to outside the optical path during general imaging and the attachment of the light shielding object to a predetermined position within the optical path are linked. Shared fundus camera.