JP2000237145A - Fundus photographing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain precise focusing with a focusing means having a simple structure. SOLUTION: A shielding member 12 is rotatively driven by a step motor 10, and it is reciprocated between a solid line A and a chain line B at the time of focusing. The opening 11 of the shielding member 12 alternately shields about halves of the light flux of a photographing aperture at the positions of the solid line A and the chain line B. When a fundus image is defocused, it has a drift in the moving direction as the shielding member 12 moves. When the fundus image is focused, it has no drift. An inspector moves a focus lens to the position where the fundus image does not move on a television monitor for focusing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus photographing apparatus used in ophthalmic hospitals and the like.

[0002]

2. Description of the Related Art Conventionally, in a non-mydriatic retinal camera that focuses on infrared light, a split luminous flux is projected on the fundus to focus on the image.

[0003]

However, in the above-mentioned conventional example, there is a problem that the configuration of an optical system for projecting a split light beam becomes complicated.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a fundus photographing apparatus having a focusing means having a simple configuration.

[0005]

A fundus photographing apparatus according to the present invention for achieving the above object is a fundus photographing apparatus for illuminating a fundus and photographing a fundus image. The fundus photographing apparatus passes through a pupil at a pupil conjugate position of an eye to be examined. A light-shielding unit that alternately shields one side and the other side of the light beam; and an imaging unit that captures a fundus image, and focuses on the basis of a shift in the fundus image of the imaging unit when the light-shielding unit alternately shields light. Is performed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 shows a configuration diagram of the first embodiment,
It is a non-mydriatic retinal camera that observes with infrared light. On the optical path O1 of the illumination optical system, a halogen lamp light source 1 for fundus observation, an infrared filter 2 for selectively transmitting infrared light, a lens 3, a strobe light source 4 for photographing, and a ring slit conjugate to the pupil P 5, lenses 6 are arranged. On an optical path O2 facing the eye E, an objective lens 7, a perforated mirror 8,
An imaging stop 9 conjugate to the pupil P, a light-shielding member 12 driven by a step motor 10 and having an opening 11, a focus lens 13, an imaging lens 14, a switching mirror 15, and a film camera 16 are sequentially arranged. A field lens 17, a relay lens 18, and a video camera 19 as an image pickup unit are arranged on the observation optical path O 3 in the reflection direction of the switching mirror 15, and the output of the video camera 19 is connected to a television monitor 20.

With such a configuration, at the time of photographing, the luminous flux from the halogen lamp light source 1 passes through the infrared filter 2, the lens 3, the ring slit 5, and the lens 6, and is reflected to the left by the perforated mirror 8, so that the objective lens 7 illuminates the fundus R through the pupil P. The light beam reflected from the fundus R passes through the pupil P, the objective lens 7, the hole of the perforated mirror 8, the photographic stop 9, the light blocking member 12, the focus lens 13, and the photographic lens 14, is reflected by the switching mirror 15, and is reflected by the field lens. 17. The image is taken by the video camera 19 through the relay lens 18, and the fundus image R 'is displayed on the television monitor 20.

FIG. 2 shows the light shielding means viewed from the direction of the optical axis O2. The light shielding member 12 is driven to rotate by a step motor 10, and moves so as to reciprocate between a solid line A and a dashed line B at the time of focus detection. Sometimes it is the position of the dotted line C.
The opening 11 of the light shielding member 12 alternately shields about half of the luminous flux of the photographing aperture 9 at the position of the solid line A and the alternate long and short dash line B, and this repetition is performed in a cycle that is easily perceived by the eyes. When focusing while observing the fundus image R ′ on the television monitor 20, the switching mirror 15 is lowered to the position shown in FIG. 1 and the fundus R is illuminated by the halogen lamp light source 1 and captured by the video camera 19. The fundus image R 'thus displayed is displayed on the television monitor 20.

When the focus is out of focus, the fundus image R 'is displaced in the direction of movement along with the movement of the light shielding member 12, and when the focus is in place, this displacement disappears. The examiner moves the focus lens 13 to a position where the fundus image R ′ does not move on the television monitor 20 to perform focusing. Although the fundus image R ′ formed by infrared rays has a low contrast, the movement of the image is recognizable, so that focusing can be performed with high accuracy.
If the fundus R has irregularities, the amount of movement of the image is partially different,
According to the present embodiment, it is possible to accurately perform a focusing operation at an arbitrary portion of the fundus R.

When focus is achieved, the photographing button is pressed, whereby the light shielding member 12 is retracted to the position indicated by the dotted line C, the switching mirror 15 is raised, the strobe light source 4 emits light, and the fundus image R 'is photographed by the film camera 16. Is done. In this case,
Since a split projection optical system is not required unlike the conventional example, the configuration can be simplified.

FIG. 3 shows a configuration diagram of a main part of the second embodiment. The configuration of the illumination light path O2 and the objective lens 7 are the same as in the first embodiment, and the same members are denoted by the same reference numerals. Driving means 21 for driving focus lens 13 and light shielding member 1
The output of the second step motor 10 is connected to the calculating means 22, and the output of the calculating means 22 is connected to the television monitor 20.

At the time of observation, the light shielding member 12 is moved so as to alternately shield one side and the other side of the pupil P, and the fundus image R 'of the video camera 19 is taken into the arithmetic means 22 to indicate the direction of movement of the opening 11. The phase difference is calculated using the signals of the scanning lines L. If the fundus image R 'shifts due to the movement of the opening 11, a phase difference occurs. Therefore, the focus lens 13 is driven by the driving means 21 so as to eliminate the phase difference, and automatic focusing is performed.

When the light shielding member 12 is moved in synchronization with the video signal, the fundus image R 'generated by the movement of the eye E is focused on the phase difference generated by the plurality of movements of the light shielding member 12 in order to identify the shift. The state is determined, and the focus lens 13 is driven. In addition, the fundus image R ′ used for the focus calculation
May be selected. For example, blood vessels are large around the nipple and the image is relatively good. Therefore, it is efficient to focus on the video signal of that portion. by this,
Good focusing is possible even if the contrast of the fundus image R 'is low.

FIG. 4 shows a front view of the light shielding means of the third embodiment.
And a focus opening 26. At the time of photographing, the photographing diaphragm aperture 25 comes on the optical axis O2 instead of the fixed photographing diaphragm 9. At the time of focusing, the focus opening 26 vibrates to both sides of the optical axis O2 by driving the step motor 10, and a light beam having a width of 2 to 3 mm is taken in the pupil P. Since the photographing aperture opening 25 has a pupil of 1 to 1.5 mm, focusing can be performed with a light beam larger than that, so that the displacement of the fundus image R 'becomes larger and focusing becomes easier.

Although the focus opening 26 is moved horizontally in the embodiment, it may be moved vertically with respect to the scanning line of the video camera 17.

[0016]

As described above, the fundus photographing apparatus according to the present invention focuses on the basis of the displacement of the fundus image of the imaging means when one side and the other side of the light beam passing through the pupil are alternately shielded by the light shielding means. , Accurate focusing can be obtained with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fundus imaging apparatus according to a first embodiment.

FIG. 2 is a front view of a light shielding unit.

FIG. 3 is a configuration diagram of a main part of a second embodiment.

FIG. 4 is a front view of a light shielding unit according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Halogen lamp light source 3 Strobe light source 5 Ring slit 8 Perforated mirror 9 Shooting aperture 11, 25, 26 Opening 12, 24 Light shielding member 15 Switching mirror 19 Video camera 20 TV monitor 22 Arithmetic means

Claims (1)

[Claims] 1. A fundus photographing apparatus for photographing a fundus image by illuminating a fundus of a fundus. A fundus photographing apparatus, comprising: an imaging unit, wherein focusing is performed based on a shift of a fundus image of the imaging unit when light is alternately shielded by the light shielding unit.