JP2977607B2 - Stereoscopic fundus camera - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera for stereoscopically photographing a fundus, and is particularly suitable for obtaining a stereoscopic image of a constant fundus region irrespective of the refractive power of a subject's eye. Related to the simultaneous stereoscopic fundus camera.

[Prior Art] The present applicant proposed an optical system of a stereoscopic fundus camera in an application patent “stereoscopic fundus camera” (name of invention) filed on October 24, 1990.

The optical system of this embodiment is shown in FIGS. FIG. 6 is a schematic layout diagram of the optical system when viewed from the side.
FIG. 7 is a top view of the photographing and observation system of FIG. Since the embodiment is basically the same as the embodiment of the present invention, the detailed description is left to the explanation of the embodiment.

The luminous flux reflected from the fundus of the eye to be examined forms an inverted first intermediate image at point A by the objective lens 13 and then the perforated mirror 12
Then, the light passes through the aperture of the light source and is separated into two light beams on the left and right by the two-hole aperture 15. The separated luminous flux is switched and separated by luminous flux separating prisms 16 and 17. Further, the light passes through the relay lens 18, the focusing lens 19, etc.
Are formed. The photographer 27 observes the fundus image of the subject's eye via the eyepiece 27.

When the eye to be inspected has a refraction abnormality, the photographer 28 moves the focusing lens 19 in the optical axis direction to adjust the refractive power of the eye to be inspected so that the fundus image of the eye to be inspected is formed on the imaging surface 23. .

[Problem to be Solved by the Invention] In the optical system as described above, the normal eye having no refractive error (the refractive error in the present specification means a refractive power different from a refractive power originally expected by the device). Then, the position of the first intermediate image at the point A moves on the optical axis X of the objective lens to the A- side for myopia and the A + side for hyperopia due to the refractive power of the eye to be examined.

At this time, since the photographing (observation) optical axes Y and Y 'have an angle determined by the optical axis X and the two-hole aperture 15, if the first intermediate image moves parallel to A- or A +, the optical axis Y , Y '(and the optical axis X), the image points A'-, A' corresponding to the on-axis image points
+ Is an off-axis image point with respect to the optical axes Y and Y '. Therefore, the second intermediate image at the eyepiece field stop 26 and the image at the film surface 23 are:
It will move horizontally on the image plane.

The horizontal movement on the image plane means that a center shift (optical axis shift) is caused for the photographer 27. Whether or not this center shift hinders the stereoscopic fusion of the photographer depends on the size of the shift amount and the balance between the photographer's eye accommodation and the center shift. This can hinder the concentration of 28 and cause stereoscopic improper viewing.

Also, on the film surface 23, there is a portion of the visual field that is not common to the left and right screens.
There is an inconvenience that a screen area that can be used for image synthesis or stereoscopically viewed is narrowed.

[Means for Solving the Problems] The present invention has the following structural features in order to achieve the above object. 1. In a stereoscopic fundus camera including an illumination optical system that illuminates the fundus via an objective lens and a photographing optical system that photographs the fundus via the objective lens, the fundus of the eye to be examined and the photographing position A first correction optical system disposed in the photographing optical system that conjugates the first and second correction optical systems, a second correction optical system that corrects a horizontal shift between left and right images caused by a refraction abnormality of the subject's eye, and a second correction optical system. Control means for controlling the operation.

2. The second correction optical system of (1) is composed of a prism or a mirror, and is characterized in that the rotation of the prism or the mirror is controlled.

3. In the stereoscopic fundus camera of (2), the imaging lens has an observation optical system or a photographing optical system that forms a fundus image at a position of the focal length, and an optical axis including the imaging lens and observation light. Alternatively, the rotation of the prism or the mirror is controlled so that the principal ray of the photographing light is substantially parallel.

4. In the stereoscopic fundus camera according to any one of (1) to (3), the observation optical system for observing the fundus is branched in the optical path of the photographing optical system for photographing the fundus, and imaging and observation are selectively performed. It is characterized by:

5. The second correction optical system of the stereoscopic fundus camera described in (4) is characterized in that the second correction optical system is arranged on the eye to be examined at a position where the observation optical system branches off from the imaging optical system.

6. The stereoscopic fundus camera according to any one of (1) to (5), further comprising a mechanism that operates in conjunction with the first correction optical system and the second correction optical system.

7. The sixth correction optical system is characterized in that the first correction optical system and the second correction optical system are mechanically connected.

8. The mechanism that operates in conjunction with (6) includes a detecting unit that detects a correction amount of the first correction optical system, and controls an operation of the second correction optical system based on a detection result by the detecting unit. It is characterized by having control means.

[Operation] In response to the movement of the first intermediate image by the objective lens due to the refractive power of the eye to be inspected, an optical member such as an angle correction prism with respect to the photographing optical axis (and / or the observation optical axis) is moved. By appropriately rotating, the apparent image can be moved on the axis, and the screen can be prevented from moving and illegal stereoscopic viewing can be prevented.

In addition, the second correction optical system of the stereoscopic fundus camera is arranged on the side of the subject's eye at a position where the observation optical system branches from the imaging optical system, so that the second correction optical system can be divided into the imaging optical system and the observation optical system. Can be shared.

Furthermore, by providing a mechanism in which the second correction optical system operates in conjunction with the focus system of the fundus camera that focuses on the first intermediate image, despite the simple mechanism,
The apparent image can be quickly and accurately moved on the axis.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration) FIG. 1 is a schematic layout diagram of an optical system when an embodiment of the present invention is viewed from the side. It consists of a target projection system that includes a visual target. FIG. 2 is a top view of the photographing and observation optical system of FIG.

Illumination optical system 1 is a halogen lamp as a light source for observation, 2 is a condenser lens, and 3 is a xenon flash lamp as a light source for photographing.

4 is a beam splitter, 5 is a relay lens, and 6 is an aperture stop. Reference numeral 7 denotes a mirror for changing the optical path, and reference numeral 8 denotes an illumination system relay lens. An illumination stop 9 has a field stop function for limiting an illumination area. Further, the illumination diaphragm 9 is provided with a mask constituting an index optical system and other functions.

Reference numeral 10 denotes a target plate having a black spot at the center and removing harmful light from the objective lens. 11 is an illumination relay lens, and 12 is a perforated mirror.

The aperture stop 6 is formed of a ring-shaped slit, forms an intermediate image of the slit near the opening of the perforated mirror 12, reflects the light on the perforated mirror 12, and then forms the slit image near the cornea by the objective lens 13. An image is formed, and the fundus of the eye 14 is illuminated.

The photographing optical system 13 is an objective lens, and 15 is a two-hole stop that bisects a light beam. The two-hole stop 15 is arranged so as to be conjugate with the pupil of the eye to be examined with respect to the objective lens 13. Further, in order to correct the change in the stereoscopic viewing angle accompanying the movement of the first intermediate image due to the refractive power of the eye to be examined, the distance between the left and right centers of the two-aperture stop 15 is configured to move in conjunction with the focusing lens 19. ing. If the distance between the centers of the apertures is fixed irrespective of the movement of the image, the stereoscopic viewing angle is shallow on the A- side and deep on the A + side with respect to the point A. FIG. 3 shows an example of a mechanism in which the two-hole stop 15 and the focusing lens 19 are mechanically linked.

The two-hole aperture 15 is composed of two aperture plates 15a and 15b, and a pin 33 is set up on each aperture plate. Each aperture plate is pulled by a spring in the left-right direction. When the focusing lenses 19a, b are moved in the front-back direction by the diopter adjustment knob 34, the pins 33 are moved in the left-right direction (in the direction of the arrow) along the guide grooves of the guide plate 35. ), And the distance between the centers of the left and right openings changes. This moving amount is uniquely determined by the moving distance of the first intermediate image due to the refractive power of the eye to be examined. The shape of the guide groove is made in relation to the amount of movement of the focusing lens 19 so that the ratio between the distance between the two-hole stop and the distance from the stop to the intermediate image is constant.

Of course, there is no need to mechanically connect the movement of the focusing lens 19 and the change in the center-to-center distance of the aperture, and a mechanism for detecting the amount of movement of the focusing lens 19 with an encoder or the like and moving the aperture plate based on the detection result. May be provided. There are various known mechanisms for controlling such two movements in relation to each other, and a description thereof will be omitted.

Further, instead of the two-hole stop moving left and right in conjunction with the focusing lenses 19a and 19b, the two-hole stop 15 moves on the optical axis C by the same distance in the same direction as the first intermediate image A moves. Even if such a mechanism is provided, the stereoscopic viewing angle can be made the same regardless of the refractive power of the eye to be examined.

16 and 17 are light beam splitting prisms. Beam splitting prism
Numeral 16 is for exchanging the left and right of the bisected light beam, and the light beam splitting prism 17 makes the left and right optical axes parallel at predetermined intervals.

18 is a relay lens, and 19 is a focusing lens. The focusing lens 19 is movable in the optical axis direction, adjusts the refractive power of the eye to be examined, and focuses the fundus image on the film surface 23.

Reference numeral 20 denotes an angle correction prism that can deflect the optical path by an arbitrary angle. The angle correction prism 20 is composed of a combination of two thin prisms 20 'and 20 ", and changes the shake angle (shake amount) in conjunction with the focusing lens 19. The mechanism is as follows.

 FIG. 4 shows an example of a mechanically linked mechanism.

Reference numeral 36 denotes a lens holder for holding the focusing 19, and the lens holder 36 is provided with a cam groove. The arm whose tip moves in the cam groove is fixed to the outer periphery of the prism holder 39 'of the prism 20'. An angle variable gear may be interposed. The shape of the cam groove is made in relation to the amount of movement of the focusing lens 19 so that the center shift (optical axis shift) of the image is corrected by the rotation of the prism.
The prism holders 39 'and 39' rotate in opposite directions via a bevel gear 40. When the prisms 20 'and 20' are rotated by an equal amount in opposite directions about the optical axis, it is possible to arbitrarily swing by a shake angle while the shake direction is fixed. The deflection angle is determined by the rotation angle of the prism and the magnitude of the vertex angle of the prism.

In this embodiment, since the optical system arranged at the image side focal length of the imaging lens 22 on the film surface 23 is employed, the observation light
The rotation (shake angle) of the prism 28 is controlled so as to give a shake angle so that the principal ray of the photographing light is parallel to the optical axis.

With this configuration, the image does not move right and left regardless of the refractive power of the eye to be inspected, and an image is always formed at a fixed position.

Of course, the movement of the focusing lens 19 and the prism 2
The rotation of 0 ′, 20 ° does not need to be mechanically connected, and the moving amount of the focusing lens 19 and the moving amount of the aperture plate 15 are detected by an encoder or the like, and based on the detection result, the prisms 20 ′, A mechanism for rotating the 20 ° (prism holders 39 ′, 39 °) may be provided. There are various known mechanisms for controlling such two movements in relation to each other, and a description thereof will be omitted.

The luminous flux reflected from the fundus of the eye to be examined forms an inverted first intermediate image at point A by the objective lens 13 and then the perforated mirror 12
Through the aperture of the aperture stop, two aperture 15, light beam splitting prism 16,
After passing through the lens 17, a fundus image is formed on the film surface 23 by the relay lens 18, the focusing lens 19, and the imaging lens 22.

Reference numeral 21 denotes a flip-up mirror, which switches the optical path between the photographing optical system and the observation optical system. At the same time as the flip-up mirror 21 is flipped up in the direction of the arrow, the xenon flash lamp 3 emits light, and the luminous flux from the fundus is guided to the film surface 23.

Observation optical system The observation optical system is shared with the optical system of the photographing optical system of the objective lens 13 to the flip-up mirror 21.

The reflected light of the observation light from the fundus led through the objective lens 13 to the focusing lens 19 is reflected by the flip-up mirror 21.
After being reflected by the mirror 24, the optical path is further changed by the mirror 24. An erect second intermediate image is formed at the position of the ocular field stop 26 by the observation system imaging lens 25, and the photographer 28 observes the fundus image of the eye to be examined via the ocular lens 27.

Index Optical System As described above, the illumination stop 9 of the illumination optical system supports a mask and the like constituting the index optical system, and is positioned conjugate with the fundus with respect to the objective lens 13 and the relay lens 11.

The mask 30 is made of a sheet glass member as shown in FIG. Reference numerals 30a and 30b are indices to be used as targets for image synthesis, and are markings that do not transmit light as in the non-transmissive area 30e of the illumination stop.

Reference numerals 30c and 30d are fixation targets for facilitating fixation of the subject, and are for the left eye and the right eye. The fixation targets 30c, 30d consist of pinholes that release light within 30e, and switch the light sources 31, 32 to light.

(Operation) The operation of the above-described embodiment of the optical system will be described.

The optical system main body accommodated in the casing has a moving table on which it is mounted and a sliding mechanism, and moves relative to the fixed table. The subject is fixed on the jaw table fixed to the fixed table, and the halogen lamp 1 as the observation light source is turned on to illuminate the eye to be examined.
The photographer slides the optical system left and right and up and down with a joystick to align the image on the cornea of the aperture stop 6 of the illumination system and the pupil of the subject's eye with a predetermined positional relationship. When the alignment is almost completed, the illumination light illuminates the fundus.

When the refracting power of the eye to be examined is the refracting power expected by the apparatus, the reflected light from the fundus forms a first intermediate image at point A after passing through the objective lens. This fundus image is an inverted image. Thereafter, the light beam passes through a perforated mirror 12 and is split into two right and left light beams by a two-hole stop 15. The light beam on the right is switched and separated. The separated light beams are reflected by the prisms 17a and 17b, respectively, and then
With a pair of imaging lens systems, namely, relay lenses 18a, b, focusing lenses 19a, b, and observation system imaging lenses 24a, b,
An image is formed on the field stops 25a and 25b of the eyepiece. This fundus image is an erect image.

If the refractive power of the eye to be examined is not the refractive power expected by the apparatus, the focusing lenses 19a and 19b are moved to adjust the focus. In the present embodiment, the focusing lenses 19a, b
In conjunction with the above operation, the above-described two-hole stop 15 moves to the left and right, and at the same time, the prism 28 rotates to give a deflection angle so that the principal ray of the observation light / photographing light is parallel to the optical axis. . That is, when the refractive power of the subject's eye is negative (near vision side), the first intermediate image by the objective lens 13 moves away from the two-hole stop 15, so the center-to-center distance of the two-hole stop is large. On the other hand, when the refractive power of the subject's eye is on the + side (far-sighted side), the distance between the centers of the two-aperture stop is small, and the direction of deflection by the prism is on the inside. Thus, the solid angle facing the first intermediate image can be always kept constant, and the image can be always observed at a fixed position without moving left and right.

In this way, the photographer observes the left and right images and turns the knob in conjunction with the focusing lenses 19a and 19b to focus on the best focus position, and at the same time there is no flare due to the illumination light on both the left and right. Fine adjustment of alignment.

When the alignment and focusing are completed and the shooting button is pressed, the flip-up mirror 20 in the shooting system jumps up in synchronization with the pressing of the shooting button, and the xenon flash lamp 3 emits light. When the xenon flash lamp 3 emits light, a fundus image is taken on the film surface.

The fundus image thus photographed is a pair of stereo images as they are stereoscopically observed by the photographer, and the stereoscopic viewing area does not narrow.

The above operation is controlled by a microcomputer (not shown) inside the apparatus except for a manual part.

In the above embodiment, the prism is arranged after the focusing lens 19, but theoretically it may be arranged anywhere, and the deflection angle may be corrected according to the position.

In addition, as an example of the configuration of the prisms, an example in which two thin prisms are combined is shown. However, a configuration in which the reflection angle is changed by one prism or mirror may be used.

Further, in the embodiment, the influence of the refractive error of the eye to be examined is completely corrected. However, without departing from the technical idea of the present invention, for example, a certain allowable range is provided, or the correction is performed stepwise. It is possible to make transformations.

[Effects of the Invention] According to the present invention, regardless of the refractive power of the eye to be inspected, it is possible to constantly photograph a fixed fundus region without moving the image, thereby observing with a binocular without irregular stereoscopic vision. There is no pain in the fusion of the middle and left images.

In addition, in image analysis, there is an effect that a wide area can be measured without narrowing a stereoscopically viewable area.

[Brief description of the drawings]

FIG. 1 is a schematic layout diagram of an optical system when an embodiment of the present invention is viewed from the side, and FIG. 2 is a diagram of the photographing and observation optical system of FIG. 1 viewed from above. FIG. 3 is an explanatory view showing a mechanism in which the two-hole stop 15 and the focusing lens 19 are mechanically linked. FIG. 4 is an explanatory view showing a mechanism in which the focusing lens 19 and the prism 20 are linked. FIG. 5 is a front view showing the mask 30. FIG. 6 is a schematic layout view of the optical system of the applicant's patent application “Stereoscopic fundus camera” filed on Oct. 24, 1990, viewed from the side. FIG. FIG. 13 Objective lens 14 Eye to be examined 15 Two-hole stop 16, 17 Beam splitting prism 18 Relay lens 19 Focusing lens 20 Prism 21 Mirror flip-up 22 Imaging lens 23 …… Film surface 25 …… Observation imaging lens 26 …… Eyepiece field stop 27 …… Eyepiece 28 …… Photographer

Claims (8)

(57) [Claims] 1. A stereoscopic fundus camera having an illumination optical system for illuminating the fundus via an objective lens and a photographing optical system for photographing the fundus via the objective lens, wherein the photographing is performed on the fundus of the eye to be examined. A first correction optical system disposed in the photographing optical system for making the position conjugate, a second correction optical system for correcting a horizontal shift between left and right images caused by a refraction abnormality of the subject's eye, and the second correction optical system A stereoscopic fundus camera, comprising: control means for controlling the operation of (1). 2. A stereoscopic fundus camera according to claim 1, wherein said second correction optical system comprises a prism or a mirror, and controls rotation of said prism or said mirror. 3. The stereoscopic fundus camera according to claim 2, wherein the imaging lens has an observation optical system or a photographing optical system that forms a fundus image at a position of the focal length, and an optical axis including the imaging lens. A stereoscopic fundus camera, wherein the rotation of a prism or a mirror is controlled so that a principal ray of the observation light or the photographing light is substantially parallel. 4. A stereoscopic fundus camera according to claim 1, wherein an observation optical system for observing the fundus is divided in the optical path of the photographing optical system for photographing the fundus, and the photographing and observation are selectively performed. A stereoscopic fundus camera characterized by performing: 5. The stereoscopic fundus camera according to claim 4, wherein the second correction optical system of the stereoscopic fundus camera is arranged on the eye to be inspected at a position where the observation optical system branches off from the photographing optical system. 6. The stereoscopic fundus camera according to claim 1, further comprising a mechanism that operates in conjunction with the first correction optical system and the second correction optical system. 7. A stereoscopic fundus camera, wherein the first correction optical system and the second correction optical system according to claim 6 are mechanically connected. 8. A mechanism according to claim 6, wherein said detecting means detects a correction amount of said first correcting optical system, and operates said second correcting optical system based on a detection result by said detecting means. A stereoscopic fundus camera, comprising: a control unit for controlling the distance.