JP2002065611A - Fundus camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for photographing a good quality fundus image to be observed when a focus index mark is projected on the fundus to be focused for fundal observation and fundal photography. SOLUTION: The light reflexed from an objective lens 11 that enters a photographic optical system is prevented by a sunspot plate 8. A light beam from a visual focus target 31 is projected on the fundus Er through a half mirror 35 arranged in an illuminating optical system, and then an image is brought into focus. Since a deviation of an optic axis due to an insertion of a half mirror is corrected by a parallel glass plate 36, the effect of the sunspot plate that prevents the reflex light from the objective lens 11 is not lost and a fine image of observation can be obtained during when the half mirror is being inserted for observation. The effect of the sunspot plate remains unchanged and a fine fundal image can be photographed as in the case of observation since the half mirror and parallel glass plate depart from an optical path when photographed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera, and more specifically, to irradiate light from an observation light source and a photographing light source to the fundus of an eye to be examined through an illumination optical system, and reflects light reflected from the fundus. The present invention relates to a fundus camera that forms an image via a photographing optical system to observe or photograph a fundus.

[0002]

2. Description of the Related Art In conventional fundus cameras, when observing or photographing the fundus, it is very difficult to focus on the fundus due to insufficient light quantity and poor contrast due to low reflectance of the fundus. there were. Therefore, a method has been adopted in which the focus index is projected onto the fundus and the focus is adjusted via the image formation state of the focus index on the fundus.

[0003]

However, when focusing is performed by projecting the focus index onto the fundus as described above, the focus index used for focusing becomes harmful light when photographing the fundus. Not be. As a light source to project the focus index,
If an LED (light emitting diode) or the like is used, the light can be turned off at a high speed, and the problem that the residual image of the focus index is captured is eliminated. A light combining means such as a half mirror and a return mirror is provided for use in the system and for guiding the focus index to the illumination optical system. Had to be eliminated.

In addition, since the optical path length of the illumination optical system cannot be increased, the light combining means must be disposed between the black point for eliminating the reflection of the objective lens and the objective lens (perforated mirror). Therefore, the insertion / removal of the photosynthesis means affects the illumination system, and the reflection of the objective lens occurs during the observation, which is a great obstacle for the subject to observe the fundus.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and when a focus index is projected on the fundus to perform focusing and fundus observation and fundus photographing, a fundus image with good image quality is obtained. It is an object of the present invention to provide a fundus camera capable of performing such operations.

[0006]

In order to achieve the above object, the present invention irradiates light from an observation light source and a photographing light source to the fundus of an eye to be examined through an illumination optical system, and reflects the light from the fundus. A fundus camera for observing or photographing the fundus by imaging light through a photographing optical system, a means for projecting a focus index on the fundus, a means for performing focus control based on the focus index projected on the fundus, and an illumination optical system. A light combining unit that can be inserted into and removed from the system and that causes light from the focus index to enter the illumination optical system when inserted, and a unit that corrects an optical axis shift of the illumination optical system caused by the insertion of the light combining unit. Is adopted.

In such a configuration, the light beam from the focus target is incident on the illumination optical system via the light combining means (half mirror), projected on the fundus, and focused. In this case, since the optical axis shift of the illumination optical system due to the insertion of the light combining means is corrected, the anti-reflection effect of the optical element (black spot plate) arranged in the illumination optical system for taking the reflection of the objective lens is hardly lost. , Will remain. Therefore, a good fundus image with less reflection from the objective lens can be obtained during observation for focusing.

The light synthesizing means is preferably realized by a half mirror. An optical axis shift generated when the half mirror is inserted into the optical path of the illumination optical system is realized by using a parallel plate glass having the same thickness as the half mirror. To be compensated for. This parallel plate glass is integrated with the half mirror and inserted into the optical path of the illumination optical system at the time of observation, and is separated from the optical path at the time of photographing, so that the optical element and objective lens for taking the reflection of the objective lens and the eye to be examined Is hardly changed by inserting and removing the parallel plate glass and the half mirror. Accordingly, the anti-reflection effect of the optical element for taking the reflection of the objective lens during observation and photographing is substantially the same, and the reflection of the objective lens is significantly reduced, so that a good fundus image can be observed or photographed. can do.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows the overall configuration of a fundus camera according to the present invention. In FIG. 1, light emitted from a lamp 1 as an observation light source illuminates a ring slit 6 through an infrared filter 2, a condenser lens 3, and a strobe 4 as an imaging light source. The ring slit 6 has a predetermined outer diameter and inner diameter, and forms an annular illumination light beam at a position substantially conjugate with the pupil Ep of the eye E to be inspected.

The luminous flux from the ring slit 6 is reflected by the objective lens 11 to form a black spot plate 8 having a black spot 8a arranged at a position substantially conjugate with a reflection virtual image 11a of a photographing diaphragm 14 generated in the objective lens 11. The light passes through a parallel plate glass 36 and an infrared half mirror 35 which will be described later, and is reflected by a perforated total reflection mirror 10 having a hole at the center via a relay lens 9. The light beam reflected by the total reflection mirror 10 is imaged by the objective lens 11 on the pupil Ep of the eye E to be examined, and then enters the fundus Er to illuminate the fundus almost uniformly with infrared light.

The reflected light from the fundus Er passes through the center of the pupil Ep again, is received through the objective lens 11, and is arranged in the optical path of the photographing optical system through the hole of the perforated total reflection mirror 10. Shooting aperture 14, focus lens 12, 1
3. The light passes through the imaging lens 15 and enters the return mirror 16. The light flux from the fundus reflected by the return mirror 16 is condensed by an imaging lens 17 onto a CCD (image pickup device) 19 having an infrared filter 18 disposed on the front surface. CC
D19 is sensitive to infrared light, so that the fundus image is
It is imaged on CD19. The fundus image captured by the CCD 19 is recorded on a video device 20 and reproduced on a monitor 21 connected to the video device 20 so that the examiner can observe the fundus image.

Behind the return mirror 16, an imaging lens 22 and a CCD 23 sensitive to visible light are arranged. The CCD 23 is connected to the video device 20 in the same manner as the CCD 19, and the return mirror 16 is used for photographing the fundus.
Is separated from the optical path and the fundus image is captured by the CCD 23,
The image is recorded on the video device 20 and the monitor 21
Can be displayed.

In the fundus camera according to the present invention, a focus index 31 having a small hole 31a formed at the center is provided for forming a focus dot on the fundus for focusing. After being illuminated by the infrared LED 33 having a large amount of light, reflected by the infrared half mirror 35 via the focus lens 34, and then combined with the light beam of the illumination optical system, the focus index 31 is projected on the fundus Er to form a focus dot. Is done.

The focus lens 34 is mechanically linked with the focus lens 13 of the photographing optical system. When the focus lens 13 is adjusted to focus on the fundus Er of the eye to be inspected by adjusting the focus lens 13, the focus index 31 is adjusted to the fundus. Er, that is, focus index 3
The position 1 is configured to be substantially conjugate with the fundus Er.

The parallel plate glass 36 has substantially the same thickness and the same refractive index as the infrared filter 35.
As shown in FIG. 2, the infrared filter 35 and the parallel plate glass 36 (the dotted line in FIG. 1) are disposed at the same inclination angle θ with respect to an axis C ′ perpendicular to the optical axis C of the illumination optical system. Is enclosed in a position shown in FIG. 1 at the time of observation, while it moves in a direction perpendicular to the drawing of FIG. 1 at the time of photographing, and separates from the optical path of the illumination optical system.

In such a configuration, at the time of fundus observation, the lamp 1 is turned on, and the luminous flux from which the wavelength range of the infrared light is extracted by the infrared filter 2 is supplied to the condenser lens 3, the ring slit 6, the black spot plate 8, After being reflected by the perforated total reflection mirror 10 through the plate glass 36, the infrared half mirror 35, and the relay lens 9, and passing through the pupil Ep of the eye E,
The light enters the fundus Er and illuminates the fundus with infrared light. Also, the reflected light from the fundus Er passes through the center of the pupil Ep, is received through the objective lens 11, passes through the hole of the perforated total reflection mirror 10, and passes through the aperture 14, the lenses 12, 13, and 15 Is reflected by the return mirror 16 through the imaging lens 17
, And the fundus image is captured by the CCD 19 having sensitivity to infrared light. The fundus image photographed by the CCD 19 is recorded on a video device 20, reproduced on a monitor 21 connected to the video device 20, and observed by an examiner.

At the time of this observation, the infrared LED 33 is also turned on at the same time, the focus index 31 is illuminated via the image prism 32, and the infrared light passing through the small hole 31a of the focus index 31 is reflected by the infrared half mirror 35. Are combined with the illumination light and projected as focus dots on the fundus Er. When the focus dot is not focused on the fundus, as shown in FIG. 3B, the focus dot is observed on the monitor 21 as a dot 40 'which is not sharp, but when the focus lens 13 is adjusted, In conjunction with this, the focus lens 34 is adjusted, and as shown by the solid line in FIG. The examiner adjusts the focus lens 13 by adjusting the focus dot reflected on the monitor 21 because the fundus image is also focused on the photographing optical system when the clear focus dot 40 is observed. By setting the focus state, it is possible to focus on the fundus.

At the time of such focusing, an infrared LED
Since the light amount of 33 is sufficient, the focus dot 40 is observed as a point that can be sufficiently identified by the examiner. Also, since the parallel plate glass 36 is arranged in the optical path of the illumination optical system,
As shown in FIG. 2A, after the optical axis passing through the black spot 8a is displaced by the parallel plate glass 36, the infrared half mirror 3
At 5, the displacement is returned to the original position, so that the optical axis after exiting the infrared half mirror 35 substantially coincides with the optical axis passing through the black spot 8a. Conventionally, as shown in FIG. 2B, the optical axis passing through the black point 8a is shifted by the infrared half mirror 35 as shown by a two-dot chain line. The axis of the objective lens 11
The reflected light from the mirror passes through the hole of the perforated total reflection mirror 10 and reaches the CCD 19, so that a good fundus image cannot be obtained. However, in the present invention, as shown in FIG. 2A, the optical axis after passing through the infrared half mirror 35 and the optical axis passing through the black spot plate 8 are substantially coincident by the insertion of the parallel plate glass 36. become. Therefore, the effect of preventing the reflected light from the objective lens by the black spot plate 8 is hardly lost, and the examiner can observe a good fundus image.

When the focusing is completed, a fundus is photographed by pressing a shutter (not shown).
At this time, the infrared half mirror 35 and the parallel plate glass 36 surrounded by the dotted line in FIG. 1 move perpendicularly to the drawing to be out of the optical path, and the return mirror 16 is also separated from the optical path.
At the same time, the strobe 4 is emitted, so that the fundus image illuminated by the strobe 4 is photographed by the CCD 23 through the objective lens 11, the hole of the total reflection mirror 10, the photographing aperture 14, and the lenses 12, 13, 15, and 22. The fundus image captured by the CCD 23 can be recorded on the video device 20 and displayed on the monitor 21.

At the time of the above-described photographing, as shown in FIG. 2C, the infrared half mirror 35 and the parallel plate glass 36 are separated from the optical path of the illumination optical system, so that an afterimage of the focus index 31 is photographed. That is, a good-quality fundus image can be taken.

[0022]

As described above, according to the present invention, the optical axis shift caused by the insertion of the light combining means (half mirror) for guiding the light beam from the focus target to the illumination optical system is corrected. Thereby, since the reflection of the objective lens is taken, the anti-reflection effect of the optical element arranged in the illumination optical system is hardly lost, so that a good fundus image can be obtained at the time of observation for focusing.

In the present invention, the light synthesizing means is inserted into the optical path of the illumination optical system together with the optical element (parallel plate glass) for compensating the optical axis deviation during fundus observation, and is separated from the optical path during photographing. The relative positions of the optical element for taking the reflection of the objective lens, the objective lens, and the subject's eye hardly change during observation and photographing. Therefore, the antireflection effect of the optical element for taking the reflection of the objective lens is substantially the same during observation and photographing, and the reflection of the objective lens is significantly reduced, so that a good fundus image can be observed or photographed. can do.

[Brief description of the drawings]

FIG. 1 is an optical diagram showing an entire configuration of a fundus camera according to the present invention.

FIG. 2 is an explanatory diagram for explaining displacement of an optical axis due to insertion of an infrared half mirror.

FIG. 3 is an explanatory diagram showing a state in which a focus dot is projected onto the fundus for focusing.

[Explanation of symbols]

 6 Ring slit 8 Black spot plate 13 Focus lens 19, 23 CCD 31 Focus index 34 Focus lens 35 Infrared half mirror 36 Parallel plate glass

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Matsumura 1-3-1 Shintoda, Hamamatsu-shi, Shizuoka Prefecture Inside the Hamamatsu Plant, Electro-Optics Division, Kowa Co., Ltd. 3-1 Kowa Co., Ltd. Electro-Optics Division Hamamatsu Factory

Claims (4)

[Claims] An illumination light system irradiates light from an observation light source and an imaging light source to an eye fundus of an eye to be examined, and forms a reflected light from the fundus through an imaging optical system to observe or observe the fundus. A fundus camera for photographing, a means for projecting a focus index on the fundus, a means for performing focus control based on the focus index projected on the fundus, and a light from the focus index which can be inserted into and removed from the illumination optical system when inserted. A fundus camera, comprising: a light combining unit that causes light to enter the illumination optical system; and a unit that corrects an optical axis shift of the illumination optical system caused by insertion of the light combining unit. 2. The fundus camera according to claim 1, wherein said light combining means is a half mirror. 3. The fundus camera according to claim 1, wherein focus control of a focus index is performed in conjunction with the focus control. 4. The apparatus according to claim 1, wherein the means for correcting the optical axis shift is a parallel plate glass having the same thickness as the half mirror, and is inserted into and removed from the illumination optical system integrally with the half mirror. 3. The fundus camera according to 2.