JPS6143055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fundus camera, particularly a fundus camera with variable magnification.

In a retinal camera with variable magnification, the illumination from the illumination system is set to the illumination field corresponding to the largest real field of view, taking into account the change in the size of the real field of view due to the variable magnification operation. Therefore, when photographing is performed under high magnification and a narrow field of view, the illumination light will illuminate more than the photographing range. In the fundus camera,
Light other than the luminous flux that illuminates the shooting range is reflected from the lens barrel,
Reflections from the lens surface become harmful rays for photographing, causing flare ghosts in photographed images. Furthermore, since the photographing magnification changes due to the magnification changing operation, the brightness of the photographed image fluctuates.

The purpose of the present invention is to solve the above-mentioned problems in conventional retinal cameras with variable magnification, and its structural features include an illumination field diaphragm in the illumination system and a variable aperture diameter in the photographic optical system. The present invention is characterized in that a diaphragm is provided, and the illumination field diaphragm and photographic diaphragm are linked to a variable power mechanism so that they can be adjusted together with the variable power operation.

According to the present invention, since the illumination field diaphragm is adjusted to an optimal value as the magnification is changed, light other than the luminous flux necessary for photographing is cut out in the illumination system, improving the quality of the photographed image. Further, according to the present invention, the photographing aperture is appropriately adjusted as the magnification is changed, so that the brightness of the photographed image can be kept constant.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The illustrated fundus camera has an aspherical objective lens 1 placed opposite to the eye to be examined, and on the optical axis 2 of this objective lens 1 there is a A perforated mirror 3 is obliquely provided on the lens 1 at a position substantially conjugate with the pupil of the eye to be examined. The illumination optical system includes xenon light source 4 for photography.
The light from the light source 4 passes through a condenser lens 5, a ring-shaped diaphragm 6, and a lens 7, is reflected by a mirror 8, passes through lenses 9 and 10, and is directed toward an objective lens 1 by a perforated mirror 3. It is reflected, passes through the lens 1, the pupil of the eye to be examined, and is projected onto the fundus. Condenser lens 5 and ring-shaped aperture 6
A half mirror 11 is disposed between the observation tungsten light source 12 , and the light from the observation tungsten light source 12 is reflected by the half mirror 11 toward the ring-shaped diaphragm 6 via a condenser lens 13 .

The photographing optical system includes a diaphragm 14 provided behind the perforated mirror 3 at a position substantially conjugate with the pupil of the subject's eye with respect to the objective lens 1, and behind the diaphragm 14,
It has a variable magnification focusing lens system 15 and an imaging lens system 16 provided along the imaging optical axis 2a, and the reflected light from the fundus passes through the diaphragm 14 and the variable magnification focusing lens system 15, and is sent to the imaging lens. Shooting film surface 1 by system 16
The image is formed on 7. The variable power focusing lens system 15 has a plurality of sets of variable power lenses 15a and 15b having different magnifications, and any one of these lenses can be inserted into the photographing optical path. Further, these variable magnification lenses can perform a focusing function by moving along the photographing optical axis 2a. A flip-up mirror 18 is arranged in front of the film surface 17.
In the illustrated position of the mirror 18, the imaging lens 1
The light from 6 is reflected by the mirror 18 and formed into an image on the focal plane 19, and is then reflected by the mirror 20 and the eyepiece 2.
Observed through 1. Mirror 1 that can be flipped up
8, a half mirror or a prism may be used.

The variable magnification focusing lens system 15 includes a rotating member 32 mounted on a rotating shaft 31 so as to be movable in the axial direction and to rotate together with the rotating shaft 31. Lenses 15a, 15b
is installed. A gear 35 is fixed on the shaft 31, and this gear 35 meshes with a gear 41 fixed on the operating shaft 37. By rotating the operating shaft 37, the rotating member 32 is rotated, and lens systems with different magnifications are rotated. is inserted into the photographing optical path. Further, the rotating member 32 can slide on the shaft 31 in the axial direction, and focusing is performed by the sliding movement. gear 35
A diaphragm plate 14 having aperture holes of different diameters is attached to the diaphragm plate 14, and the photographing diaphragm is also adjusted in synchronization with the change in magnification caused by the rotation of the rotating member 32.

In the illumination system, a variable diaphragm 50 is arranged between the lenses 9, 10, which variable diaphragm is adjusted by a gear 52 on a shaft 51 and changes the illumination field. A bevel gear 53 is attached to the end of the shaft 51, and this bevel gear 53 meshes with a bevel gear 55 fixed to a pulley 54. The pulley 54 is connected to a pulley 57 by a timing belt 56, and a bevel gear 58 fixed to the pulley 57 meshes with a bevel gear 59 provided at the end of the operating shaft 37. Therefore, the rotating member 32
When the zoom lens rotates and zooming is performed, the variable diaphragm 50 and the diaphragm plate 14 are also adjusted at the same time, and the illumination field and photographing diaphragm are set to appropriate values depending on the angle of view of the variable magnification focusing lens used.

As explained above, according to the present invention, the illumination field diaphragm and the photography diaphragm are adjusted in conjunction with the variable magnification mechanism, so that appropriate illumination is performed according to the magnification of the photography optical system, and the illumination field diaphragm and photography diaphragm are adjusted in conjunction with the magnification change mechanism. Not only can the quality of photographed images be improved by cutting out harmful light fluxes, but also it is possible to obtain photographed images with appropriate brightness depending on the magnification. Furthermore, there is no need to separately adjust the illumination field diaphragm and photographic diaphragm.

[Brief explanation of the drawing]

The drawing is a schematic diagram of an optical system of a fundus camera showing an embodiment of the present invention. 1... Objective lens, 4, 12... Illumination light source, 1
5... Variable magnification focusing lens, 32... Rotating member, 50
...Variable aperture.

Claims (1)

[Claims] 1. In a fundus camera consisting of an illumination system that projects illumination light through an objective lens placed opposite the eye to be examined, and a photographic optical system that forms an image of the reflected light flux from the eye to be examined on a photographic film surface, the photographic optical system is is provided with a variable magnification lens system for changing the magnification and an imaging diaphragm with a variable aperture diameter, the illumination system is provided with an illumination field diaphragm with a variable aperture diameter, and the imaging diaphragm and the illumination field diaphragm are variable. A fundus camera capable of variable magnification, characterized in that it is adjusted in conjunction with variable magnification operations using a magnification lens system.