JPS5854821B2 - fundus camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fundus camera that is equipped with a photographing optical system and a sub-optical system for observing the armpit of an eye to be examined, and is capable of selectively displaying a fundus image and a pupil image of the eye to be examined.

When photographing a fundus image with a fundus camera, in order to prevent the reflected light from the eyeball surface of the fundus illumination light flux from deteriorating the fundus image formed on the film surface, it is necessary to prevent the reflected light from reaching the recording surface. It is necessary to prevent this.

Furthermore, it is necessary to ensure that ghosts and flares do not exist in the image on the recording surface of the fundus illuminated by the fundus illumination light beam.

When photographing the fundus, the light is passed through the pupil into the eyeball,
It is necessary to adjust the position of the armpit of the eye to be examined relative to the optical axis of the imaging optical system so that the imaging light can be extracted without coasting, flare, or reflected light from the ocular surface deteriorating the fundus image on the recording surface. be.

In order to adjust the position of the pupil with respect to the optical axis and the distance from the objective lens (hereinafter referred to as pupil alignment), conventionally, the subject was fixed using a face fixing means etc. arranged in front of the camera. The camera operator was looking into the person's eyes from the side of the camera system while adjusting the position of the camera system relative to the person's eyes.

However, such pupil alignment requires moving the eye from the fundus observation system, and if the distance between the objective lens and the pupil is short, it may be difficult to see into the eye to be examined, which may be inconvenient. In addition, since the pupil is observed off the optical axis of the imaging system, it is difficult to align the pupil accurately and requires skill.

In addition, in order to avoid discomfort to the subject and damage to the eyes, we do not use mydriatics, but instead irradiate the subject's eye with infrared rays while keeping the pupil in a naturally dilated state in a dark room. For fundus cameras that use a system that focuses the camera and determines the photographic field of view, it may be necessary to also perform pupil positioning using infrared rays.

In this case, it is impossible for the camera operator to directly look into the subject's eye from the side and perform pupil alignment.

An object of the present invention is to provide a pupil image format optical system having an optical axis that coincides with the photographing optical system for the eye to be examined, together with the photographing optical system, so that the fundus image and the pupil image can be selectively displayed. In addition, the fundus camera is compact in the optical axis direction, making it possible to always observe a clear pupil image without changing the focus adjustment state of the imaging system on the fundus, making it possible to perform pupil alignment accurately, easily and efficiently. It is about providing.

Still another object of the present invention is to provide a fundus camera that also enables pupil image observation using infrared rays.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

1 is an eye to be examined whose fundus is photographed.

The subject's face is placed in front of the objective lens 3 of the fundus camera.
The eye 1 to be examined is fixed by appropriate means so as to face the objective lens 3.

3 is an objective lens. Reference numeral 4 denotes a photographing system relay lens, which records the fundus image formed by the objective lens 3 on or near the rear focal plane F of the lens 3 on a recording surface 5 and a surface 6 optically equivalent thereto (described later). ).

4' A color photographic film, for example, is placed on the recording surface 5, which is an aperture placed close to the beam lens 4.
0γ, on which the fundus image is exposed and recorded, is an optical path switching mirror that is freely disposed in and out of the optical path between the relay lens 4 and the recording surface 5, and when adjusting the pupil position, focusing, etc., the recording surface 5 The optical system is set obliquely in front of the camera, bends the optical path from the photographing optical system and the pupil image forming optical system (described later), and guides the optical path to the observation system (described later).

This optical path switching mirror γ and the optical path switching mirror 2 described later
2.23.37 is not limited to the swing-up mirror shown in the figure, but may be a combination of a half mirror and a shutter, for example.

FIG. 1 Embodiment 1 Here, the surface 6 optically equivalent to the recording surface 5 described above is symmetrical to the recording surface 5 with respect to the reflective surface of the optical path switching mirror γ installed obliquely in the optical path described above. It is an aspect of the relationship.

That is, when an image formed on the recording surface 5 is formed on this equilateral surface 6 in an equivalent imaging state, this is considered to be an optically equivalent surface.

8 is a light source for fundus illumination, 9 is a concave mirror, 10 is a condenser lens, and 15 is a ring slit.

The light emitted from the light source 8, including a portion of the light reflected by the concave mirror 9, is focused onto the ring slit 13 by the condenser lens 10.

The ring slit 13 has a ring-shaped light transmitting part as shown in FIG.
becomes a secondary light source that emits a ring-shaped light.

A filter 11 that transmits only infrared rays is disposed between the condenser lens 10 and the light source 8 so as to be removable.

The image of the ring slit 13 is formed on a conjugate plane with respect to the objective lens 3 of @2 of the eye 1 to be examined.

Therefore, the image of the ring slit 13 is formed on the pupil 2.

Therefore, a ring-shaped light beam is incident on @2, and by illuminating the fundus with such a ring-shaped light beam, the illumination light that is reflected by the surface of the eye to be examined and travels backward along the imaging optical path is diverged in a conical shape. When the eye 1 to be examined is fixed at a predetermined distance from the objective lens 3, it is possible to prevent the reflected light from overlapping the fundus image formed on the recording surface 5 or the isometric surface 6, and By allowing the photographing light beam to pass through the center of the ring light beam on the oblique surface, both light beams can be separated at the pupil plane, thereby preventing ghosts and flare.

1γ is a strobe light source, 18 is a concave mirror 119 is a condenser lens, and the light emitted from the strobe light source 11, including a portion of the light reflected by the concave mirror 18, is focused onto the ring slit 13 by the condenser lens 19. Ru.

An optical path switching mirror 12 is provided between the link slit 13 and the condenser lens 19 so as to be able to be put in and out.
When photographing the fundus of the eye, the light from the light source 8 is blocked and the light from the strobe light source is allowed to pass in the direction of the ring slit 13, as shown by the broken line in Figure 1. .

The optical path of the BA light irradiation for illuminating the fundus is established between the mirror 16 and the eye to be examined 1 by an optical path integrating mirror 16 installed in the optical path of the photographing system between the objective lens 3 and the relay lens 4. It is integrated into the optical path of this imaging system.

The optical path integrating mirror 16 may be a half mirror or a hole having a predetermined diameter that blocks the illumination light from the ring slit 13 and the light reflected on the surface of the eye to be examined, and completely transmits the light from the fundus. The perforated mirror does not reduce the amount of light necessary for fundus image observation and photography, and directs the reflected light to the recording surface 5.
, etc. This is convenient because it can be shielded from any surface.

Reference numeral 20 denotes a pupil illumination light source, which is arranged so as to illuminate @2 of the eye 1 from the side of the optical path of the photographing system or the like.

A filter 21 that transmits only infrared rays is disposed between the light source 20 and the eye 1 to be examined, and can be inserted and removed freely.

22 and 23 are the objective lens 3 and the optical path integrating mirror 16, respectively.
This is an optical path switching mirror that is freely disposed in and out of the optical path of the photographing system between the relay lens 4 and the optical path switching mirror γ.

As shown by the solid lines in FIG. 1, when the mirrors 22 and 23 are set obliquely in the optical path, the optical path bypassing the relay lens 4 of the photographing optical system is opened, as shown by the broken lines. When each mirror 22, 23 is removed from the optical path, the detour optical path is closed and an optical path by the photographing optical system is opened.

The above detour optical path is the optical path of the pupil observation optical system.
In the illustrated embodiment, the pupil observation optical system includes an objective auxiliary lens 24.
, a field lens 25, a chart 26, and relay lenses 27 and 28.

The relay lens 2γ is arranged so that its front focal point is on the chart 26.

Therefore, the beam of light emitted from the chart 26 is converted into a parallel beam of light by the lens 2γ.

The relay lens 28 is arranged so as to be on a plane 6 that is optically equivalent to the rear focal plane 5).

(When the optical path is bent, the focal point in this case is considered to be a point separated by the focal length along this bent optical path) , are imaged onto the chart 26 by the field lens 25.

The objective auxiliary lens 24 reduces the magnification of the image @2,
This allows the pupil image to be observed in a wide field of view.

The chart 26 is a diagram drawn on a transparent plate, as shown in FIG. 2B.

The relay lenses 2γ, 26 re-image the image of the pupil 2 formed on the chart 26 onto a surface 6 optically equivalent to the recording surface 5.

Mirrors 29 and 30 are respectively chart 26 and relay lens 2
γ, it is disposed in the optical path of the sub optical system between the relay lens 28 and the optical path switching mirror 23, and bends this optical path to bypass the relay lens 4.

31 is an observation field lens, and the recording surface 5
It is disposed near a surface 6 that is optically equivalent to .

32 is the eyepiece lens of the finder, and the equivalent surface 6
A fundus image and a pupil image formed by the photographing optical system and the pupil observation optical system are displayed.

(However, at this time, both the fundus and @2 are illuminated with visible light.

) 33 is a relay lens, which re-images the fundus image and pupil image formed on the equivalent surface 6 onto the light receiving surface of the infrared imaging tube 34.

(In this case, infrared light illuminates the fundus and @2.

Therefore, in front of the light sources 8 and 20, filters 11 and 21 that transmit only infrared rays are arranged.

) The electric signal formed by the image pickup tube 34 is applied to the monitor television 35, and the fundus image and the pupil image are selectively displayed on the cathode ray tube of the monitor television 35.

It is obvious that any other means for converting an infrared image into a visible image, such as an image tube, can be used in place of the IFF tube 34 and the monitor television 35. When a light beam image is formed, the light beam is directed to the eyepiece lens 32, and when an infrared image is formed, the eyepiece lens 32 is blocked as shown by the broken line in FIG. 1, and the relay lens 33 , the camera is designed to direct the red light in the direction of the image pickup tube 34.
To focus the fundus camera on the fundus of eye 1,
In the embodiment shown in FIG. 1, all or part of the position of the lens 4 of the photographing optical system may be moved along the optical axis, or the focus position of this lens 4 may be changed.

In the former case, the relative positions of the recording surface 5 and its optically equivalent surface 6 with respect to the objective lens 3 remain unchanged.

Therefore, even if the focal length of the sub-optical system for observation remains unchanged, a clear pupil image can always be formed on the equivalent surface 6 no matter what state of focus the relay lens 4 has on the fundus.

Therefore, the objective auxiliary lens 24, the field lens 25,
Chart 26, relay lens 2γ, 28, mirror 29.
The relative position of the lens 30 with respect to the objective lens 3 may be fixed.

However, in a fundus camera in which the recording surface 5 is moved back and forth along the optical axis for focus adjustment, an eyepiece is inevitably used to display the image formed on the equivalent surface 6. The lens 32, relay lens 33, and image pickup tube 34 are also moved along the optical axis so as to correspond to the recording surface 5.

At this time, as mentioned above, if the focal length of the @observation optical system remains unchanged, as the recording surface 5, and therefore the isometric plane 6, moves, the @2 image formed thereon by the pupil observation optical system. The image is blurred, and therefore a blurred pupil image is displayed on the observation system.To avoid this, in an embodiment in which the recording surface 5 is moved to adjust the focus of the photographing optical system, the recording surface 5 is Corresponding to the movement, the lens 28 of the pupil observation optical system is moved along the optical axis so that the rear focal point of this lens always coincides with the recording plane 5 and therefore with the optically equivalent plane 6. It looks like this.

Therefore, as described above, even if the recording surface 5 and the optical system of the observation system move, the pupil image formed on the chart 26 can always be accurately formed on the equivalent surface 6 by the relay lenses 2γ and 28. , a clear pupil image can be displayed on a monitor TV or viewfinder of the observation system.

When photographing the fundus in the embodiment shown in FIG. 1, the subject's face is first fixed at a predetermined position so that the subject's eye 1 faces the objective lens 3.

The optical path switching mirrors 22 and 23 are set in the optical path of the photographing system as shown by solid lines in FIG. 1, the optical path passing through the pupil observation optical system is opened, and the optical path of the photographing optical system is closed.

The optical path switching mirror γ is also set as shown by the solid line in FIG.

The pupil of the eye 1 to be examined is illuminated with the pupil illumination light source 20, the pupil image displayed on the observation system and the image of the chart 26 are observed, and the distance between the fundus camera and @2 is adjusted so that the pupil image is clear. Adjust.

At this time, the distance between the pupil 2 and the objective lens 3 is set correctly.

While observing the chart 26 and the image of pupil 2 with the observation system, move the fundus camera vertically and horizontally with respect to the eye to be examined so that the image of pupil 2 is focused on the line diagram of chart 26 in a predetermined relationship. adjust.

(The optical system shown in Figure 1 is housed in the camera frame)
It is installed on the camera stand.

The camera can be adjusted by moving forward, backward, up, down, left and right on the camera stand.

: When the pupil alignment is completed in this manner, the optical path switching mirrors 22 and 23 are removed from the optical path of the photographing optical system as shown by broken lines in FIG. 1, thereby closing the detour optical path and opening the optical path of the photographing optical system.

Next, the optical path switching mirror 12 is set as shown by the solid line in Fig. 1, and the fundus illumination light source 8 emits light to illuminate the fundus, and the fundus image is displayed on the observation system through the N photographing optical system and observed. The above-mentioned fundus image can be made clear by moving the recording surface 5 and the optical system of the observation system as described above while determining the photographic field of view, or by moving all or part of the relay lens 4 or by changing the focus position. Adjust the focus so that the

When focusing is completed in this manner, the optical path switching mirrors 1 and 12 are removed from the optical paths of the photographing optical system and strobe illumination system as shown by broken lines in FIG. 1, and the strobe light source 1γ is caused to emit light and placed on the recording surface 5. The fundus image is recorded on a recording means such as photographic film.

When photographing the fundus with the subject's eye in a state of natural mydriasis, such as during the solstice, without using a mydriatic agent, filters 11 and 21 that transmit only infrared rays are used for fundus illumination and pupil illumination light source 8, respectively.
, 20, and excludes the optical path switching mirror 36 from the optical path between the field lens 31 and the relay lens 33 as shown by broken lines in FIG. means for converting an infrared image into a visible image;
In the embodiment shown in FIG. 1, the image is displayed as a visible image using an infrared television, and while observing this image, the pupil position is adjusted and the eye fundus is focused.

Although not shown in FIG. 1, each optical path switching mirror is linked by mechanical or electrical means to move as described above.

Each light source also blinks in mechanical or electrical correlation with the interlocking of the mirrors.

FIG. 3 is an explanatory diagram of another embodiment of the present invention.

In this figure, the fundus illumination system, which is integrated into the optical path of the imaging optical system by the optical path integrating mirror 16 shown in FIG. 1, is not shown for convenience.

1 is the eye to be examined.

When observing the pupil image, the light source 20 is turned on to illuminate the eye 1 to be examined from the side.

A filter 21 that transmits only infrared rays is disposed between the eye 1 to be examined and the light source 20 so as to be removable.

3 is an objective lens, 4 is a photographing system relay lens, 5 is a film surface, γ is an optical path switching mirror, 31 is a field lens, 32 is an eyepiece lens, 33 is a relay lens for an imaging tube, 3
4 is an infrared imaging tube, 36 is an optical path switching mirror,
The arrangement, function, and operation of each member described above are approximately the same as shown in FIG. 1.

However, in the embodiment shown in FIG.
2, or a fundus image is displayed or formed on the light receiving surface of the image pickup tube 34, and a pupil image is displayed or imaged on the eyepiece lens 38 of the finder and the image pickup tube 40 (described later).

An optical path switching mirror 3γ is disposed in the optical path between the objective lens 3 and the relay lens 4 so that it can be taken in and out.

When observing the image of the pupil 2, the mirror 31 is set obliquely in the optical path of the imaging system, as shown by the solid line in FIG.
Close the optical path by the photographing optical system and open the optical path by the observation optical system.

24 is an objective auxiliary lens, 25 is a field lens, 26
is a chart such as that illustrated in FIG. 2B.

Reference numeral 38 is an eyepiece of the finder, 39 is a relay lens for an image pickup tube, and 40 is an infrared image pickup tube.The objective auxiliary lens 24, the field lens 25, the chart 26, the eyepiece 38, the relay lens 39, and the image pickup tube 40 are the objective lenses. fixed relative to the

An image @2 of the eye 1 to be examined is formed on a chart 26 by the objective lens 3, the auxiliary objective lens 24, and the field lens 25.

If the pupil image formed on this chart 26 is based on infrared rays, therefore, if the filter 21 that transmits only infrared rays is placed between the pupil illumination light source 20 and the eye 1 to be examined, the pupil image will be The image is re-imaged on the light receiving surface of the infrared camera tube 40 by the camera tube relay lens 38 .

The electrical signal formed by this image pickup tube is transmitted to the monitor television 35.
' is applied to the monitor television 35', which visualizes the pupil image using infrared rays. Electric signals from the image pickup tube 34 (for fundus image) and the image pickup tube 40 (@trust) are applied to the switch means 42.
It is input by switching as appropriate.

If the image of the pupil 2 formed on the chart 26 is based on visible light, and therefore the filter 21 is removed from between the light source 20 and the eye to be examined, as shown by the broken line in FIG. An optical path switching mirror is set obliquely in front of the relay lens 39 as shown by the broken line in FIG. 3, and the pupil image formed on the chart 26 is displayed through the WIIJ lens of the finder.

The optical system for observing @2 described above is arranged so that the distance relationship relative to the objective lens 3 remains unchanged.

When photographing the fundus of the eye, first align the pupil position, then adjust the focus of the photographic optical system to the lens 4.
Even if the optical path switching mirror 3γ is moved along the optical axis or the focal length is changed, or the recording surface 5 is moved along the optical axis, the optical path switching mirror 3γ is set in the optical path of the photographing optical system regardless of this focus adjustment operation. , it is possible to always observe a clear pupil image simply by switching to the optical path using the pupil observation optical system.

In the embodiment shown in FIG. 3, the pupil image and the fundus image can be switched and displayed on the same display means, that is, the monitor television 35', when pupil positioning, focusing, and imaging field determination are performed using infrared rays. Eye alignment using light,
In the case of focusing and determining the photographic field of view, each is performed by looking through separate eyepiece lenses 38 and 32.

However, either the pupil image formed on the chart 26 is transmitted to the eyepiece 32 by an optical system such as a lens and a mirror, or the fundus image formed on a surface 6 optically equivalent to the recording surface 5. If the image is transmitted to the eyepiece lens 38 through an optical system such as a lens or a mirror, the pupil image and the fundus image can be switched and displayed on the same finder.

FIG. 4 is an explanatory diagram of another embodiment of the present invention.

The general structure of the optical system etc. is almost the same as the embodiment shown in FIG. 1 and the embodiment shown in FIG.

Therefore, illustration of the fundus illumination system, recording surface, etc. is omitted.

24' is an objective auxiliary lens, 25' is a field lens, and 26' is a chart as shown in FIG. 2B.

Reference numeral 37 denotes an optical path switching mirror, which is set obliquely in front of the photographing system relay lens 4 when observing the pupil image, as shown in this figure, and is used when adjusting the focus on the fundus, determining the photographic field of view, and exposing the film. It is excluded from the valve path of the imaging system as shown by the broken line in this figure.

That is, the mirror 31 selectively opens and closes the optical path of the photographing optical system and the optical path of the observation optical system.

The photographing auxiliary lens 24', the field lens 25', and the chart 26' are integrated into a small lens barrel and constitute an objective auxiliary unit 43.

This unit 43 includes an objective lens 3 and an optical path switching mirror 3.
The unit 43 can be moved in and out of the optical path between the units 7 and 7 so that the optical axis of the photographing system and the optical axis of the unit 43 coincide with each other.

The unit 43 is disposed in the optical path when observing a pupil image to form an optical path for pupil observation, and is removed from the optical path when adjusting the focus on the fundus, determining the photographic field of view, and exposing the film.

The image @2 of the eye 1 to be examined is the objective lens 3 and the objective auxiliary lens 2.
4. Field lens 25, chart 26'
is imaged.

The light flux from this image is reflected by the optical path switching □shi 3γ and re-imaged on the light receiving surface of the image pickup tube 40 by the relay lens 39, so that the pupil image is displayed on the monitor television.

When the eye to be examined is illuminated with visible light, the image @2 formed on the chart 25' can be observed through the viewfinder lens as shown in FIG.

As shown in FIG. 4, by arranging the objective auxiliary lens 24 and the like close to the objective lens 3, it is possible to widen the field of view when observing the pupil image.

It is also possible in the embodiment shown in FIG. 1 to form the objective auxiliary lens, field lens, and chart into units that can be freely inserted and removed into the optical path between the objective lens and the optical path switching mirror in front of the photographing system. be.

As described above, according to the fundus camera of the present invention, since the eye to be examined is equipped with a pupil image forming optical system having an optical axis that coincides with the photographing optical system, accurate pupil positioning can be easily performed. Moreover, regardless of the state of focus adjustment on the fundus, it is possible to always observe a clear pupil image of the eye to be examined without changing the photographing optical system that is in the focused state, and the pupil image and fundus image can be selected. It is possible to switch the display according to the pupil alignment,
Efficient focus adjustment.

In addition, by inserting an infrared selective filter into the illumination optical path from outside the optical path and displaying an infrared image on the observation system, pupil positioning can be done simply by inserting a single light source and filter into and out of the optical path. The operation process from focusing to determining the field of view can be performed using infrared rays, eliminating the need for mydriatics.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the fundus camera of the present invention, and FIG.
Figures A and B are explanatory diagrams of the elements of the optical system of the embodiment in Figure 1, and Figure 3.
FIG. 4 is an explanatory diagram of another embodiment of the fundus camera of the present invention, and FIG. 4 is an explanatory diagram of another embodiment of the fundus camera of the present invention. 3 is an objective lens, 4 is a lens for photographing optical system, 5 is a recording surface, 6 is a surface optically equivalent to the recording surface 5, 20 is a light source for pupil illumination, 21 is a filter that transmits only infrared rays, 2
2.23 is an optical path switching mirror, 24 is an objective auxiliary lens, 2
6 is a chart, 32.38 is a finder eyepiece, 33.39 is a relay lens, 34.40 is an infrared camera tube, and 35.35' is a monitor TV.

Claims (1)

[Scope of Claims] 1. Imaging that includes an objective lens facing the eye to be examined and a relay lens that reimages the fundus image of the eye to be examined formed by the objective lens on a recording surface and a surface optically equivalent thereto. an optical system; a fundus illumination system having a light source for illuminating the fundus of the eye to be examined; and a first wavelength selection means that is inserted into and taken out of the illumination optical path to select visible light and infrared light; and the recording surface. an observation system that selectively provides a means for visually observing a visible image on an optically equivalent surface or a means for displaying an infrared image on the equivalent surface as a visible image; a pupil image forming optical system that is selectively used with the imaging optical system and forms a pupil image of the eye to be examined on the optically equivalent surface by sharing only the objective lens; An anterior segment illumination system comprising a light source for illuminating the anterior part and a second wavelength selection means that is inserted into and taken out of the illumination optical path and selects visible light and infrared light together with the first wavelength selection means. , a fundus camera that enables observation of the fundus and pupil image, as well as observation using visible light and infrared light.