JP2974751B2 - Fundus camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera, and more particularly to a fundus camera capable of automatically controlling an appropriate exposure amount.

(Prior Art) In a conventional fundus camera, as shown in FIG.
An illumination system 17 is formed by an observation light source 1, a relay lens 2, an imaging light source 3, a relay lens 4, and a reflection mirror 5, and an objective lens 7, a perforated mirror 6, a focusing lens 8, an imaging lens 9, and a film 11 Thus, an observation / photographing system 18 is formed.

A part of illumination light for fundus oculi observation is detected by a photodetector 16 by a half mirror 14 or the like provided between the reflection mirror 5 and the perforated mirror 6 on the illumination optical path 17 and the reference light amount is measured. Next, a part of the fundus reflection light extracted from the observation imaging system 18 by the half mirror 10 is
The light quantity is detected by detecting at step 13. By not-shown control unit, compares the amount of light measured by the reference light quantity and the light detector 13 as measured by the optical detector 16 obtains the reflectance from the fundus E _R of the eye E, is photographing light source Xenon lamp 3
The amount of light emitted is determined, and fundus photography is performed.

(Problems to be Solved by the Invention) In the conventional fundus camera described above, the light flux for exposure detection is a part of the observation light reflected by the fundus of the eye to be examined.
Since it is used, the amount of observation light is reduced, and sufficient observation cannot be performed. Further, when the examiner observes the fundus of the eye to be examined, in order to adjust the amount of illumination to be easy to see for each examiner, even if the reflectance of the fundus of the examinee's eye is the same, the reflection input to the detector depends on the intensity of the illumination light. The amount of light changes. For this reason, a configuration for correcting a change in the amount of illumination light must be provided separately.

The present invention has been made in view of such a problem of the conventional fundus camera, and determines the exposure amount without using the observation light amount, and determines the imaging condition even if the examiner generates the illumination light. It is an object of the present invention to provide a fundus camera in which the reference light amount does not change.

(Constitution of the Invention) In order to solve the above problems, the present invention provides an illumination system for illuminating the fundus of the eye to be examined with light in a first wavelength range, and an observation and imaging system for observing and photographing the fundus of the eye to be examined. A fundus camera having an exposure light source provided on a light path different from the light 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 a light beam from the exposure light source and performs photometry.

(Operation) In the above configuration, the illumination system illuminates the fundus of the subject's eye with observation light that is the first wavelength range. The observation illumination light is reflected from the fundus, and the examiner focuses and observes the fundus via the observation photographing system. After capturing a desired visual field by observation, the image is taken by illuminating the fundus with imaging light. An exposure light source, which is a light source for determining a photographing exposure amount, is disposed on an optical path different from the optical path of the illumination system, and is different from the first wavelength range of the illumination system.
Is used. The light beam from the exposure light source reflected by the fundus is received by the photodetector and measured.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Fundus camera of the working example, as shown in FIG. 1, the observation imaging system 150 for observing the fundus oculi E _R of the eye E, an illumination system 160 for illuminating the fundus E _R, metering system 170 Consists of

Observation imaging system 150 includes an objective lens 1 which are sequentially arranged from the side of the eye E in the observation photographing optical axis 151 passing through the eye pupil E _P
09, Focusing lens 1 moving on optical axis 151 for focusing
10, an imaging lens 111, a half mirror 112, and a film 113 are provided. Further, the first optical axis which is the reflection optical axis of the
On the photometric optical axis 153, a first photodetector 114 is arranged. Or more members, the image of the fundus E _R is the objective lens 109 and the focusing lens 1
After forming an image on the first image forming plane E _E between the film 113 and the film 113 by the focusing lens 110 and the image forming lens 111,
And are arranged so as to form an image on the first photodetector 114 arranged in a conjugate with the above.

The illumination system 160 is arranged between the objective lens 109 and the focusing lens 110, apertured mirror 108 disposed substantially conjugate to a subject's eye pupil E _P, with a reflective optical axis of該有Ana perforated mirror 108 On a certain illumination optical axis 162, a relay lens 107, a ring stop 106, and a half mirror 10 are sequentially arranged from the side of the perforated mirror 108.
5, a relay lens 104, an infrared cut filter 103, a Xe lamp 102 as a light source for photographing, a relay lens 101, and a halogen lamp 100 as a light source for observation.

The ring stop 106 is disposed conjugate with the perforated mirror 108 with respect to the relay lens 107, and the Xe lamp 102
4, the halogen lamp 100 is arranged conjugate with the Xe lamp 102 with respect to the relay lens 101.

On the transmission optical axis 164 of the half mirror 105 opposite to the perforated mirror 108, a relay lens 116 and an infrared light emitting diode 11 are provided.
5 is arranged. Infrared light emitting diode 115 is a relay lens
The lens 116 is conjugate with the ring stop 106.

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

As shown in FIG. 2, the reflection characteristic of the half mirror 105 has a reflectance of 100% in a region shorter than 700 nm.
The longer region has a reflectivity of 50%.

The reflection characteristic of the half mirror 112 is such that the reflectance is 0% in a region shorter than 700 nm and 100% in a region longer than 700 nm.
%.

The ring stop 106 is, as shown in FIG.
And a ring-shaped slit 106 centered on.

Next, the operation of the optical system will be described with reference to the block diagram of the electric control system shown in FIG. First halogen lamp 100 of the observation light source turned on to illuminate the eye fundus E _P by the light beam which cuts infrared light by an infrared cut filter 103 in the light beam from the halogen lamp 100. Observation light flux reflected by the fundus E _P is observed by imaging the observation system (not shown) by the observation imaging system 150. The focusing lens 110 is moved while performing this observation to perform focusing.

When focusing is completed, turn on the light source switch 200 for shooting and turn X
The e-lamp 102 is turned on to start fundus photography. at the same time,
The infrared light emitting diode 115 is turned on, and 50% of the infrared light beam that has passed through the relay lens 116 is reflected by 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 reaches the fundus E _R is reflected by the perforated mirror 108. The infrared light beam reflected by the fundus E _R of the subject's eye is focused on the imaging lens 11.
The light reaches the first photodetector 114 via 1 or the like.

Outputs of the first photodetector 114 and the second photodetector 117 are amplified by preamplifier circuits 202 and 204, respectively, and are input to an arithmetic circuit 201. In the arithmetic circuit 201, film sensitivity information is input via the film sensitivity setting unit 203 prior to fundus photographing. The arithmetic circuit 201 determines an appropriate illumination light amount as a function of the initial output of the second photodetector 117 and the film sensitivity information, while counting the output of the first photodetector 114,
When this count reaches the appropriate amount of illumination, the Xe lamp
The lighting of 102 is stopped, and the fundus photography ends.

(Effects of the Invention) According to the present invention, light having a wavelength range different from that of illumination light is used as an exposure light source, and a photodetector that detects only light in that wavelength range is provided. In addition, an appropriate exposure can be determined without being affected by observation illumination light.

[Brief description of the drawings]

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. 3 is another half mirror used in the fundus camera of the embodiment. FIG. 4 is a plan view of a ring diaphragm used in the fundus camera of the embodiment, FIG. 5 is a block diagram of an electric control system of the fundus camera of the embodiment, and FIG. FIG. 100 Halogen lamp 102 Xe lamp 105 Half mirror 106 Ring stop 109 Objective lens 114 First photodetector 115 Infrared photodiode 117 Second photodetector E _R …… Eye fundus to be examined

Claims (3)

(57) [Claims] 1. A fundus camera having an illumination system for illuminating a fundus of a subject's eye with light in a first wavelength range, and an observation photographing system for observing and photographing the fundus of the subject's eye, wherein an optical path of the illumination system is An exposure detection light source provided on another optical path for examining an exposure state of the fundus of the eye to be examined with light of a second wavelength range different from the first wavelength range, and receiving a light beam from the exposure detection light source A fundus camera comprising: 2. A light detector for receiving and measuring the light beam from the light source for exposure detection, a first light detector for receiving and measuring the light beam without passing through the eye to be inspected, and a reflected light beam from the fundus of the eye to be inspected. 2. The fundus camera according to claim 1, further comprising a second photodetector that receives and measures light. 3. A control means for controlling an optimum photographing light amount of said illumination system based on a result detected by said first photodetector and a result detected by said second photodetector. The fundus camera according to claim (1) or (2).