JPS627296Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fundus camera equipped with a light-receiving element for autostroboscopic, working distance detection, and the like.

Some fundus cameras are equipped with an auto strobe or a working distance detection mechanism. In such a fundus camera, for example, a light-receiving element must be placed to detect the image of the cornea, so an optical system is required to guide light from the imaging and observation optical system of the fundus camera to the light-receiving element. shall be.

The present invention was devised in view of the above points, and uses an optical system that does not use a special optical system or has an extremely simple configuration, that is, an observation and photographing optical system that is separated from the illumination system, and allows the light beam to be transmitted from the optical system into an observation and photographing optical system that is separated from the illumination system. The present invention provides a fundus camera equipped with a small reflecting mirror having a dividing semi-transparent surface.

EMBODIMENT OF THE INVENTION The fundus camera of this invention is demonstrated based on the Example shown below. In Figure 1, 1 is a light source, 2
is a condenser lens, 3 is a ring slit placed at the image position of the light source 1 formed by the condenser lens 2, 4 is a relay lens, 5 is a ring slit, and 6 is placed on the optical axis near the ring slit 5. It is a small reflecting mirror, and its reflecting surface 6a is a semi-transparent surface. 7 is a reflecting mirror, 8 is an objective lens, 9
10 is a relay lens, 11 is a switching reflector, 12 is a reflector, 13 is an eyepiece, 14 is a film surface, and 15 is provided at the center of the ring slit 5 on the side opposite to the small reflector 6. It is a light receiving element. Incidentally, a ring slit generally serves as a light shielding portion except for the ring-shaped opening, but the ring slit in FIG. 1 is transparent at least in front of the light receiving element 15.

In the fundus camera of the present invention having such a configuration, light from the light source 1 forms an image on the ring slit 3 by the condenser lens 2. Subsequently, the light passing through the ring slit 3 is imaged by the relay lens 4 on the ring-shaped opening of the ring slit 5. The light passing through the ring slit 5 forms an image of the ring slit on the cornea of the eye 9 to be examined by the objective lens 8, and then illuminates the fundus of the eye. In other words, ring lighting is performed. The illuminated fundus image passes through the objective lens 8, is reflected by the reflecting surface 6a of the reflecting mirror 7 and the small reflecting mirror 6, passes through the relay lens 10, and is transferred to the switching reflecting mirror 1.
1. It is reflected by the reflecting mirror 12 and observed by the eyepiece lens 13. When the switching reflector 11 is switched to the position 11', a fundus image is formed on the film surface 14. As mentioned above, in the fundus camera of the present invention, the reflecting surface 6a of the small reflecting mirror is a semi-transmissive mirror, so a part of the light passes through this semi-transmissive mirror and passes through the light receiving element 1.
Reach 5. Here, since the image of the anterior segment of the subject's eye 9 is formed near the small reflecting mirror, the light passing through the semi-transparent surface forms an image of the anterior segment near the light receiving element 15. Therefore, based on the detection by the light receiving element 15, it can be used for auto strobe and adjustment of the working distance.

FIG. 2 shows an enlarged view of only the vicinity of a small reflecting mirror in which a light receiving element is arranged in another second embodiment. In this invention, a concave portion 6'b is provided in the small reflecting mirror 6' and a light receiving element 15 is disposed therein, and a surface 6'a which is a semi-transparent surface is used as in the first embodiment. The transmitted light is detected by the light receiving element 15. Note that 5a is an opening of the ring slit, and 5b is a light shielding portion.

FIG. 3 is an enlarged view of the vicinity of the light receiving element of the third embodiment. In this embodiment, a prism 16 is provided on the back side of the small reflecting mirror 6, and the light transmitted through the semi-transparent surface 6a of the small reflecting mirror 6 is totally reflected by the prism 16 and then reflected by the lens 17 onto the light receiving element 15. The light is focused and incident.

As explained above, the fundus camera of the present invention is equipped with a small reflector having a semi-transparent surface that splits the light beam from the optical system in the observation/photographing optical system that is separated from the illumination system. It is possible to receive the reflected light flux from the fundus or the anterior segment of the eye, and by placing the light receiving element at an optical position suitable for the above purpose with respect to the ring slit, it is possible to focus and expose the fundus or anterior segment of the eye. The amount of light detected and the auto strobe mechanism can capture the light flux that can determine the exposure timing. No special optical system is required to introduce this light, and even if one is used, it can be an extremely simple one. Therefore, the loss of light quantity is small, the structure of the fundus camera is simple, and no extra optical elements are required, so assembly and adjustment are easy.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the optical system of the first embodiment of the present invention, and FIGS. 2 and 3 are enlarged views of the vicinity of the light-receiving element arrangement location of the second and third embodiments, respectively. 5...Ring slit, 6...Small reflector, 8...
... Objective lens, 9 ... Eye to be examined, 10 ... Relay lens, 13 ... Eyepiece lens, 14 ... Film surface, 15 ... Light receiving element.

Claims (1)

[Scope of utility model registration request] In a fundus camera equipped with a ring slit and used to observe and photograph the fundus image of the subject's eye illuminated by illumination light passing through the ring slit, a camera is installed near the ring slit on the optical axis of the optical system in order to reflect the light from the fundus. A fundus camera characterized by having a small reflector whose reflective surface is a semi-transparent surface.