JPH057553A - Retinal camera - Google Patents

Abstract

PURPOSE:To achieve accurate exposure control by preventing the mixing of flare spots into reflected light on the eyeground, for example, even when alignment between the retinal camera and an eye to be inspected deviates. CONSTITUTION:In a retinal camera which has a photographing illumination optical system 10 and a observation photographing illumination optical system 20, a stop (flare spots removing stop 66) with an effective diameter thereof smaller than a photographing stop 31 of the photographing illumination optical system 10 is provided at the position almost conjugated with the photographing stop 31. A control means (arithmetic control circuit 19) is provided which compares the eyeground reflected light obtained through the flare spots removing stop 66 with the eyeground illumination light to control a quantity of emission of a light source 11 for photographing by determining an eyeground reflection factor of an eye E to be inspected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera having an automatic exposure function.

[0002]

2. Description of the Related Art Conventionally, a fundus camera having an automatic exposure function for automatically controlling the amount of light emitted from a light emitting light source for photographing has been known.

In this fundus camera, a half mirror or the like is provided at a position on the film surface side of the photographing diaphragm in the photographing optical path to divide the photographing optical path, and an optical sensor is arranged at a position conjugate with the fundus of the eye to be examined or a position conjugate with the pupil. Was arranged to measure the amount of reflected light of the fundus reflected light.

[0004]

However, even if the alignment between the fundus camera and the eye to be examined is slightly misaligned, flare such as corneal reflected light is mixed in the fundus reflected light, and accurate exposure control cannot be performed. There was a point.

The present invention has been made in view of the above problems, and an object thereof is to prevent flare from being mixed in the fundus reflected light even when the alignment between the fundus camera and the subject's eye is misaligned. It is to provide a fundus camera capable of preventing and accurately controlling exposure.

[0006]

In order to achieve the above object, a fundus camera according to the present invention is a fundus camera having a photographing illumination optical system and an observation photographing illumination optical system, which is smaller than the photographing diaphragm of the photographing illumination optical system. A diaphragm is provided at a position that has an effective aperture and is substantially conjugate to the photographing diaphragm, and the fundus reflection light obtained through the diaphragm and the fundus illumination light are compared to obtain the fundus reflectance of the eye to be examined for photographing. It is characterized by having a control means for controlling the amount of light emitted from the light source.

[0007]

With the fundus camera according to the present invention, the fundus reflected light, which is compared with the reference light amount of the illumination light by the control means at the time of photographing, has an effective passage area narrowed by the diaphragm and is positioned at a position conjugate with the photographing diaphragm in the divided optical path. Since it becomes the central part excluding the peripheral part of the photographic aperture image formed on, even if the alignment between the fundus camera and the subject's eye is slightly misaligned, flare such as corneal reflected light is included in the measured fundus reflected light. It does not mix.

[0008]

Embodiments of the fundus camera according to the present invention will be described below with reference to the drawings.

The optical system of the fundus camera shown in FIG. 1 includes a photographing illumination optical system 10, an observation photographing illumination optical system 20, and a photographing optical system 3.
0, the observation optical system 40.

The photographing illumination optical system 10 includes a xenon tube 11, a condenser lens 12, as a light source for illuminating the subject eye for photographing.
It has optical members such as a ring slit 13, a reflecting mirror 14, a harmful reflected light removing member 15, a relay lens 16, a perforated mirror 17, and an objective lens 18 in the stated order, and illuminates the xenon tube 11 with illumination light. The image is guided and projected onto the fundus Ef of.

The harmful reflected light removing member 15 is provided with black dots 15a for removing the harmful reflected light.

The observation / photographing illumination optical system 20 includes a halogen lamp 21 as a light source for illuminating the eye to be observed, a condenser lens 22, and the condenser lens 12 to the objective lens 18.
It has the optical members up to and guides the illumination light of the halogen lamp 21 onto the fundus Ef of the eye E to be examined.

The photographing optical system 30 includes an objective lens 18, a perforated mirror 17, a photographing diaphragm 31, a focus lens 32,
Further, it has an optical member such as an imaging lens 33, and guides the fundus reflected light to the film F through the center hole 17a of the perforated mirror 17 and projects and forms a fundus image on the film F surface.

The observation optical system 40 includes optical members such as a quick return mirror 41, a prism 42, and an eyepiece lens 43, which are located between the image forming lens 33 and the film F and appear and disappear in the optical path of the photographing optical system 30. Have

Further, a prism mirror 50 as a light beam splitting optical member is disposed between the condenser lens 12 and the ring slit 13 of the observation / photographing illumination optical system 20, and the halogen lamp 2 is provided by the prism mirror 50.
An illumination light splitting optical path 51 is formed in which a part of the illumination light of No. 1 is split. A part of the divided illumination light is guided to the illumination light photometric sensor 52. The reference light amount is measured by the illumination light metering sensor 52.

A prism mirror 60, which serves as a light beam splitting optical member, is provided between the photographic stop 31 and the focus lens 32 of the photographic optical system 30 so as to be freely inserted and removed.
A reflected light splitting optical path 61 is formed through which a part of the reflected light from the fundus Ef is guided via the prism mirror 60. A part of the guided fundus reflected light is guided to the fundus reflected light photometric sensor 65 via a field lens 62 integrally formed with the prism mirror 60, a sample field angle determining diaphragm 63, and a relay lens 64.

With this sensor 65 for measuring fundus reflected light,
Sample field angle determination diaphragm 6 via field lens 62
The light quantity of the reflected light from the fundus oculi Ef formed in the vicinity of 3 is measured.

On the entrance surface 60a of the prism mirror 60,
As shown in FIG. 2, a light shielding portion 66 having a circular opening 66a at the center is formed by, for example, a vapor deposition film, and this light shielding portion 66 functions as a flare removing diaphragm. The light shielding portion 66 may be formed on the reflecting surface or the emitting surface other than the incident surface 60a.

The circular aperture 66a has an effective diameter smaller than that of the photographic diaphragm image formed by the photographic diaphragm 31 of the photographic optical system 30 at a position conjugate with the photographic diaphragm in the reflected light splitting optical path 61. The fundus Ef image is formed at a position in the divided optical path 61 that is conjugate with the photographing diaphragm.

This prism mirror 60 is retracted immediately after it is inserted into the optical path for photographing by operating a shutter button (not shown) during photographing. When the prism mirror 60 is inserted into the photographing optical path, the fundus reflected light is input to the fundus reflected light photometric sensor 65 to measure the reflected light amount, and the measured reflected light amount and the illumination light photometric sensor 5 are measured.
2 is compared with the reference light amount measured, and the arithmetic control circuit (control means) 19 (see FIG. 1) uses the xenon tube 1
The emitted light amount of 1 is controlled.

At this time, an effective passage area of the fundus reflected light input to the fundus reflected light photometric sensor 65 is narrowed by the flare removal diaphragm 66, and the photographing diaphragm 31 is used as the photographing diaphragm 31 in the reflected light splitting optical path 61. Only the central portion of the photographic aperture image formed at a conjugate position excluding the peripheral portion.

Therefore, even if the alignment between the fundus camera and the eye E is slightly misaligned, flare such as corneal reflected light is not mixed in the fundus reflected light input to the fundus reflected light photometric sensor 65. Accurate measurement of fundus reflected light is possible.

[0023]

The fundus camera according to the present invention is a fundus camera having a photographing illumination optical system and an observation photographing illumination optical system, which has an effective aperture smaller than the photographing aperture of the photographing illumination optical system and is substantially the same as the photographing diaphragm. A diaphragm is provided at a conjugate position,
It is characterized by further comprising control means for comparing the fundus reflected light obtained through the diaphragm and the fundus illumination light to obtain the fundus reflectance of the eye to be examined and controlling the light emission amount of the photographing light source.

Therefore, even if the alignment between the fundus camera and the subject's eye is misaligned, flare is prevented from being mixed in the reflected light of the fundus and accurate exposure control can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an optical system of a fundus camera according to the present invention.

FIG. 2 is a perspective view showing a flare removing diaphragm inserted in a photographing optical path.

[Explanation of symbols]

 10 Photographing Illumination Optical System 11 Photographing Light Source 19 Calculation Control Circuit (Control Unit) 20 Observation Photographing Illumination Optical System 31 Photographing Aperture 66 Flare Eliminating Aperture (Aperture) E Eye to be Inspected

Claims (1)

Claim: What is claimed is: 1. A fundus camera having a photographing illumination optical system and an observation photographing illumination optical system, which has an effective aperture smaller than that of the photographing illumination optical system and is substantially conjugate with the photographing diaphragm. A stop is provided at the position, and a fundus reflection light obtained through the stop is compared with the fundus illumination light, and a control means for controlling the light emission amount of the light source for photographing by obtaining the fundus reflectance of the eye to be examined is provided. Characteristic fundus camera.