JPH04150831A - Eyeground camera - Google Patents

Abstract

PURPOSE:To keep a quantity of light unchanged as reference to determine photographing conditions regardless of variations in illumination light with a person to be inspected by arranging a light source for detecting exposure to examine exposure condition of an eyeground of an eye to be inspected by light with a second wavelength range differing from the first wave-length range and a photo detector which receives a luminous flux from the light source for detecting exposure to measure light. CONSTITUTION:Outputs of a first photo detector 114 and a photo detector 117 are amplified with respective preamplification circuits 202 and 204 to be impinged into an arithmetic circuit 201, into which film sensitivity information is inputted through a film sensitivity setting section 203 prior to the photographing of an eyeground. The arithmetic circuit 201 determine a proper quantity of illumination light with an initial output of a second detector 117 and the film sensitivity information as function. On the other hand, an output of the first photo detector 114 is counted and when the counts reach the proper quantity of illumination light, the lighting of a xenon lamp 102 is stopped to end the photographing of the eyeground. This enables the determining of a proper exposure free from effect of observation illumination light with no reduction in the illumination light.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fundus camera, and particularly to a fundus camera that can automatically control the appropriate photographic exposure amount.

(Prior art) In a conventional fundus camera, as shown in FIG. 7, a perforated mirror 6, a focusing lens 8, an imaging lens 9, and a film 11 form an observation and photographing system 18.

A part of the fundus observation illumination light is detected by the photodetector 16 using a half mirror 14 or the like provided between the reflection mirror 5 and the perforated mirror 6 in the illumination optical path 17, and the reference light amount (2) is measured. Next, a part of the light reflected from the fundus taken out by the half mirror 10 from the observation photographing system 18 is detected by the photodetector 13 via the relay lens 12, and the light amount (2) is measured. A control device (not shown) compares the reference light amount ■ measured by the photodetector 16 and the light amount ■ measured by the photodetector 13, calculates the reflectance from the fundus E of the eye E, and calculates the reflectance from the fundus E of the eye E. After determining the amount of light emitted from the xenon lamp 3, the fundus of the eye is photographed.

(Problems to be Solved by the Invention) In the conventional fundus camera described above, a part of the observation light reflected from the fundus of the subject eye is used as the light flux for exposure detection, so the amount of observation light is reduced. As a result, sufficient observations cannot be made.

In addition, when the examiner observes the fundus of the examinee's eye, in order to adjust the amount of illumination light that is easy to see for each examiner, even if the reflectance of the fundus of the examinee's eye is the same, the intensity of the illumination light is input to the detector. The amount of reflected light changes.

Therefore, it is necessary to separately provide a configuration for correcting changes in the amount of illumination light.

The present invention was made in view of the above problems of conventional fundus cameras, and it determines the exposure amount without using the observation light amount, and even if the intensity of illumination light varies depending on the examiner, the imaging conditions can be determined. The purpose of the present invention is to provide a fundus camera that does not change the amount of light used as a reference.

(Structure of the Invention) In order to solve the above problems, the present invention provides an illumination system for illuminating the fundus of an eye to be examined with light in a first wavelength range, and an observation and photographing system for observing and photographing the fundus of an eye to be examined. and an exposure light source that is provided on an optical path different from the optical path of the illumination system and for examining the exposure state of the fundus of the eye to be examined with light in a second wavelength range different from the first wavelength range. and a photodetector that receives and measures the light flux from the exposure light source.

(Function) In the above configuration, the illumination system illuminates the fundus of the eye to be examined with observation light in the "th" wavelength range. The observation illumination light is reflected from the fundus of the eye, and the examiner focuses and observes the fundus through an observation and photographing system. After capturing a desired field of view through observation, the fundus is illuminated with photographic light and photographed. The exposure light source, which is a light source for determining the photographic exposure amount, is arranged on an optical path different from the optical path of the illumination system, and uses light in a second wavelength range different from the first wavelength range of the illumination system. The light beam from the exposure light source reflected on the fundus of the eye is received by a photodetector and photometered.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the fundus camera of the embodiment
an observation and photographing system 150 for observing and photographing the fundus E of the eye;
An illumination system 160 for illuminating the fundus E, and a photometry system 17
Consists of 0.

The observation and photography system 150 includes an objective lens 109 that is sequentially arranged from the side of the eye E on an observation and photography optical axis 151 that passes through the eye to be examined *Ep, and a focusing lens that moves on the optical axis 151 to perform focusing. It has a lens 1.1.0, an imaging lens 111, a half mirror 112, and a film 113. Further, a first photodetector 114 is arranged on the first photometric optical axis 153 which is the reflected optical axis of the flip-up mirror 112 . The above members are
The image of the fundus E! is located on the first imaging plane E! between the objective lens 109 and the focusing lens 110. After the image is formed, the focusing lens 110 and the imaging lens 111 are arranged so that the image is formed on the film 113 and the first photodetector 114 arranged conjugately with the film 113.

The illumination system 160 includes an objective lens 109 and a focusing lens 110.
A perforated mirror 108 is disposed at a position substantially conjugate with the pupil E of the eye to be examined, and the perforated mirror 10 is placed on the illumination optical axis 162 which is the reflection optical axis of the perforated mirror 108.
A relay lens 107, a ring aperture 106, a half mirror 105, and a relay lens 104 are arranged sequentially from the 8 side.
, infrared cut filter 103, Xe light source for photography
It has a lamp 102, a relay lens 101, and a halogen lamp 100 which is a light source for observation.

The ring diaphragm 106 is arranged conjugately with the perforated mirror 108 with respect to the relay lens 107, the Xe lamp 102 is arranged conjugately with the ring diaphragm 106 with respect to the relay lens 104, and the halogen lamp 100 is arranged conjugately with the Xe lamp 102 with respect to the relay lens 101. Placed.

A relay lens 116 and an infrared light emitting diode 115 are arranged on the transmission optical axis 164 of the half mirror 105 on the opposite side to the perforated mirror 108 . Infrared light emitting diode 11
5 is conjugate with the ring aperture 106 regarding the relay lens 116.

The second half mirror 105 opposite the Xe lamp 102
A second optical pressure detector 117 is arranged on the photometric optical axis 166. The second photodetector 117 is connected to Xe with respect to the relay lens 104.
It is conjugate with the lamp 102.

As shown in Figure 2, the reflection characteristics of the half mirror 105 are 100% reflectance in a region shorter than 700 nm.
In a region longer than 700 nm, the reflectance is 50%.

The reflection characteristics of the half mirror 112 have a reflectance of 0% in a region shorter than 700 nm, and a reflectance of 100% in a region longer than 700 nm.

The ring diaphragm 106, as shown in FIG.
It has a ring-shaped slit 106 centered at 62.

Next, the operation of the optical system will be explained based on the block diagram of the electrical control system shown in FIG. First, the halogen lamp 100 as the observation light source is turned on, and the halogen lamp 100
The fundus E of the subject's eye is illuminated with a light flux from which infrared light is cut by an infrared cut filter 103. The observation light flux reflected by the fundus E of the eye to be examined is sent to the observation photographing system 1.
50 to form an image on an observation system (not shown) for observation.

While performing this observation, the focusing lens 110 is moved to perform focusing.

When focusing is completed, the photographing light source switch 200 is turned on to light the Xe lamp 102 and fundus photographing is started.

At the same time, the infrared light emitting diode 115 lights up, and 50% of the infrared light flux passing through the relay lens 116 is transmitted to the half mirror.
105 and enters the second photodetector 117.

On the other hand, 50% of the infrared light transmitted through the half mirror 105 is reflected by the perforated mirror 108 to the fundus E of the subject's eye.
reach. The infrared light flux reflected by the fundus E of the eye to be examined reaches the first photodetector 114 via the imaging lens 111 and the like.

The outputs of the first photodetector 114 and the second photodetector 117 are
The signals are amplified by preamplifier circuits 202 and 204, respectively, and enter the arithmetic circuit 201.

In the arithmetic circuit 201, film sensitivity information is inputted via the film sensitivity setting section 203 prior to fundus imaging. The arithmetic circuit 201 determines the appropriate amount of illumination light as a function of the initial output of the second photodetector 117 and the film sensitivity information, and counts the output of the first photodetector 114. When the amount of illumination light is reached, lighting of the Xe lamp 102 is stopped and fundus photography is completed.

(Effects of the Invention) According to the present invention, light in a wavelength range different from that of illumination light is used as an exposure light source, and a photodetector is provided that detects only light in that wavelength range, so that the illumination light is not reduced. , appropriate exposure can be determined without being affected by observation illumination light.

[Brief explanation of the drawing]

FIG. 1 is an optical diagram of a fundus camera according to an embodiment of the present invention, FIG. 2 is a reflection characteristic diagram of a half mirror used in the fundus camera of the embodiment, and FIG. - Figure 4 is a plan view of the ring diaphragm used in the fundus camera of the embodiment, Figure 5 is a block diagram of the electrical control system of the fundus camera of the embodiment, and Figure 6 is a diagram of the conventional fundus camera. FIG. 100...Halogen lamp 102...Xe lamp 105...Half mirror 106...Ring aperture 109...Objective lens 114...First photodetector 115...Infrared light diode 117...・Second photodetector E,... Fundus diagram of the examined eye (2! length nm) Diagram (wavelength nm)

Claims (3)

[Claims] (1) In a fundus camera having an illumination system for illuminating the fundus of the subject's eye with light in a first wavelength range and an observation and photographing system for observing and photographing the fundus of the subject's eye, the optical path is separate from the optical path of the illumination system. an exposure detection light source disposed on the optical path for examining the exposure state of the fundus of the eye to be examined with light in a second wavelength range different from the first wavelength range; and a light source for receiving the light flux from the exposure detection light source. A fundus camera characterized by comprising a photodetector for photometry. (2) A first photodetector that receives and measures the light flux from the exposure detection light source without going through the eye to be examined;
2. The fundus camera according to claim 1, comprising: a photodetector; and a second photodetector that receives and measures the reflected light flux from the fundus of the eye to be examined. (3) A claim characterized in that the invention further comprises a control means for controlling the optimum photographing light amount of the illumination system based on the detection result of the first photodetector and the detection result of the second photodetector. The fundus camera according to item (1) or item (2).