JPH04295332A - Fundus camera - Google Patents

Abstract

PURPOSE:To provide a fundus camera capable of removing harmful reflection light reliably at visible lighting and at infrared lighting by installing only one black-dot plate on a lighting optical system and not plural black-dot plates CONSTITUTION:On an optical path of a lighting optical system l, a black-dot plate which removes harmful reflection light based on surface reflection of an object glass 13 at visible lighting is to be installed in a certain position, and another black-dot plate which removes other harmful reflection light based on surface reflection of the object glass 13 at infrared lighting is to be installed in another certain position. Between those positions, another black-dot plate 23 is installed to be used both for removing the harmful reflection light at visible lighting and for removing the other harmful reflection light at infrared lighting.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fundus camera capable of performing visible light photography and infrared light photography.

0002

BACKGROUND OF THE INVENTION Fundus cameras have been known that can perform visible light photography and infrared light photography depending on the purpose of examination. This fundus camera uses approximately 400 to 700 nm for visible color photography and approximately 50 nm for visible fluorescence photography.
In infrared fluorescence photography, illumination light with a wavelength of approximately 760 nm is used. These illumination lights are guided to the fundus of the eye through the objective lens of the photographic optical system, illuminating the fundus, and the reflected light or fluorescence from the fundus is guided to a film or CCD camera through the photographic optical system to produce visible color images and fluorescent images. It is now possible to obtain .

0003

[Problems to be Solved by the Invention] By the way, in this type of fundus camera, illumination light is irradiated onto the fundus through the objective lens, so a part of the illumination light is reflected by the surface of the objective lens, and this surface reflection is The harmful reflected light may enter the photographing optical system, and images captured by a film or CCD camera may deteriorate due to the harmful reflected light. Therefore, in order to remove this harmful reflected light, a sunspot plate is installed in the optical path of the illumination optical system, but the wavelength when photographing with visible light and the wavelength when photographing with infrared illumination are significantly different. If the same sunspot plate is installed in the optical path of the illumination optical system and a sunspot image is formed in the optical path of the photographic optical system, the position of the sunspot image will be largely shifted in the optical axis direction of the photographic optical system. Since harmful reflected light cannot be reliably removed, a sunspot plate for visible illumination and a blackspot plate for infrared illumination have been separately provided with their positions shifted in the optical axis direction of the illumination optical system. However, in a configuration in which multiple sunspot plates are provided, the overlap of the sunspot plates increases the vignetting of the illumination light, and the shadow that appears in the center of the fundus of the illumination light also becomes darker, and this shadow appears as a ghost in the photographed image. There was a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fundus oculi that can reliably remove harmful reflected light during visible illumination and infrared illumination by providing a single sunspot plate in the illumination optical system without having to provide a plurality of sunspot plates. The purpose is to provide cameras.

[0005]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the fundus camera according to the present invention has a method that prevents harmful reflections caused by surface reflections of the objective lens during visible illumination in the optical path of the illumination optical system. Between the position where a black spot plate for removing light should be provided and the position where a black spot plate should be provided for removing harmful reflected light based on surface reflection of the objective lens during infrared illumination,
It features a black spot plate that can be used to remove harmful reflected light from visible lighting and harmful reflected light from infrared lighting.

Preferably, a photographing diaphragm for visible light is insertably provided in the optical path of the photographing optical system in correspondence with a position where a sunspot image is to be formed during visible illumination, and a sunspot image is formed during infrared illumination. The present invention is characterized in that an infrared fluorescence photographing diaphragm is insertably provided in the optical path of the photographing optical system in correspondence with the position where the photographing optical system is to be photographed.

[0007]

[Operation] According to the fundus camera of the present invention, the position of the sunspot image formed during visible illumination and the position of the sunspot image formed during infrared illumination are shifted in the optical axis direction of the photographing optical system. However, if an aperture stop for photographing is provided corresponding to each illumination, harmful reflected light can be reliably removed in any case.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the fundus camera according to the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is an illumination optical system, and 2 is a photographing optical system. The illumination optical system 1 includes a halogen lamp 3 as an observation light source, a condenser lens 4, a xenon lamp 5 as a photography light source, a condenser lens 6, and a ring-shaped aperture 7.
, a relay lens 8, a mirror 9, and a relay lens 10. An exciter filter 11 for visible fluorescence and an exciter filter 12 for infrared fluorescence are removably provided in the optical path between the condenser lens 6 and the ring-shaped diaphragm 7. The visible fluorescence exciter filter 11 is inserted into the optical path when photographing visible fluorescence. The infrared fluorescence exciter filter 12 is inserted into the optical path during infrared fluorescence photography.

The photographing optical system 2 is roughly composed of an objective lens 13, a perforated mirror 14, a focusing lens 15, a variable magnification lens 16, an imaging lens 17, and a CCD camera 18. A visible fluorescence barrier filter 19 and an infrared fluorescence barrier filter 20 are removably provided in the optical path between the perforated mirror 14 and the focusing lens 15. The barrier filter 19 for visible fluorescence is the exciter filter 1 for visible fluorescence.
It is inserted into the optical path in conjunction with the insertion of optical path No. 1. The infrared fluorescence barrier filter 20 is inserted into the optical path in conjunction with the insertion of the infrared fluorescence exciter filter 12 into the optical path. The objective lens 13 faces the eye E to be examined. The ring-shaped diaphragm 7 includes relay lenses 8 and 10, and an objective lens 1.
3, it is provided at a substantially conjugate position with the pupil p of the eye E to be examined. Position where visible fluorescence barrier filter 19 or infrared fluorescence barrier filter 20 is inserted and perforated mirror 1
A photographic aperture 21 for visible light and a photographic aperture 22 for infrared light are provided on the optical path between the two. Visible light photography aperture 21
is inserted into the optical path in conjunction with the insertion of the visible fluorescence exciter filter 11 into the optical path. The photographing diaphragm 22 for infrared light is inserted into the optical path in conjunction with the insertion of the exciter filter 12 for infrared fluorescence into the optical path. Between the mirror 9 and the relay lens 10, there is a visible illumination harmful reflected light removal/infrared light that removes harmful reflected light based on surface reflection of visible illumination light and infrared illumination light on the surfaces 13a and 13b of the objective lens 13. A sunspot plate 23 is provided for both purposes of removing harmful reflected light from illumination. That is, the sunspot plate 23 is located at a position K1 where a sunspot plate is provided to remove harmful reflected light based on surface reflection of the objective lens 13 during visible illumination, and at a position K1 where a black spot plate is to be provided to remove harmful reflected light based on surface reflection of the objective lens 13 during infrared illumination. Position K where a sunspot plate for removing light should be provided
It is provided between 2. As shown in FIG. 2, the black spot plate 23 is provided with two light shielding parts 23a and a light shielding part 23b.

For visible illumination, the light shielding portion 23a is conjugate with the visible light photographing aperture 21 with respect to the surface 13a of the objective lens 13. Further, the light shielding portion 23b is conjugate with the visible light photographing aperture 21 with respect to the surface 13b of the objective lens 13. On the other hand, during infrared illumination, the light shielding part 23a
It is conjugate with the photographing aperture 22 for infrared light with respect to the surface 13a of No. 3. Further, the light shielding portion 23b is formed on the surface 13 of the objective lens 13.
It is conjugate with the photographing aperture 22 for infrared light with respect to b. Therefore, a sunspot image is formed at the position of the photographic aperture 21 for visible light or at the position of the photographic aperture 22 for infrared light.

FIG. 1 shows the state of the optical system when photographing visible fluorescence, in which a visible fluorescence exciter filter 11, a visible fluorescence barrier filter 19, and a visible light photographing aperture 21 are inserted into the optical path. Illumination light from the halogen lamp 3 is guided to a visible fluorescence exciter filter 11 via a condenser lens 4 and a condenser lens 6. The exciter filter 11 for visible fluorescence is approximately 500 nm.
The illumination light with a wavelength of is used as the excitation illumination light. This excitation illumination light is turned into a ring-shaped light beam by a ring-shaped diaphragm 7 and guided to a sunspot plate 23 via a relay lens 8 and a mirror 9. A shadow formed by the light shielding parts 23a and 23b of the sunspot plate 23 is imaged on the photographing aperture 21 for visible light. The illumination light that has passed through the sunspot plate 23 is guided to the objective lens 13 via the relay lens 10 and the hole 14a of the perforated mirror 14. Assuming that there is no sunspot plate 23, a part of the illumination light guided to the objective lens 13 is reflected by the surfaces 13a and 13b of the objective lens 13, and reaches the visible light photographing aperture 21 as harmful reflected light. Illumination light that can become harmful reflected light is cut off by the sunspot plate 23, so that it does not reach the photographic aperture 21 for visible light.

FIG. 3 shows a second embodiment, in which only one visible light/red filter is provided between the insertion position of the visible fluorescence barrier filter 19 or the infrared fluorescence barrier filter 20 and the perforated mirror 14. An external light common photographing aperture 24 is provided. The light shielding part 23a of the sunspot plate 23 is located between a position where the surface 13a of the objective lens 13 is conjugate with the visible light/infrared light common photographing aperture 24 when visible light is used, and a position where it is conjugate with the surface 13a of the objective lens 13 when the light is visible. The light shielding part 23b is located in the middle between the position where the surface 13b of the objective lens 13 is conjugate with the visible light/infrared light common photographing aperture 24 when visible light is used, and the position where it is conjugate with the surface 13b of the objective lens 13 during visible light and the position where it is conjugate during infrared light. It is located in This also makes it possible to remove harmful reflected light.

[0014]

Effects of the Invention Since the fundus camera according to the present invention is constructed as described above, visible illumination and infrared illumination can be achieved by providing only one sunspot plate in the illumination optical system without providing multiple sunspot plates. This has the effect of reliably removing harmful reflected light at the time of the eye, further reducing vignetting of the illumination light because a plurality of sunspot plates are not provided, and further reducing the shadow caused by the illumination light at the center of the fundus.

[Brief explanation of drawings]

FIG. 1 is an optical layout diagram showing a fundus camera according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a sunspot board of the fundus camera according to the first embodiment of the present invention.

FIG. 3 is an optical layout diagram showing a fundus camera according to a second embodiment of the present invention.

[Explanation of symbols]

1 Illumination optical system 2 Photography optical system 13 Objective lens 21 Photography aperture for visible light 22 Photography aperture for infrared fluorescence 23 Sunspot board

Claims (2)

[Claims] Claim 1: A position in the optical path of the illumination optical system where a black spot plate is to be provided to remove harmful reflected light due to surface reflection of the objective lens during visible illumination, and a position on the objective lens during infrared illumination. A fundus of the eye, characterized in that a sunspot plate for both visible illumination harmful reflected light removal and infrared illumination harmful reflected light removal is provided between a position where a sunspot plate for removing harmful reflected light based on surface reflection is to be provided. camera. 2. A sunspot image based on visible illumination and a sunspot image based on infrared illumination are formed on the optical path of the photographing optical system shifted in the optical axis direction, and the position where the sunspot image is formed during visible illumination. 2. The fundus of the eye according to claim 1, further comprising a visible light photographing diaphragm that can be inserted into the fundus, and an infrared fluorescence photographing diaphragm that can be inserted at a position where a sunspot image is formed during infrared illumination. camera.