JP3023148B2 - Stereoscopic fundus camera - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereoscopic fundus camera, and more particularly to a simultaneous stereoscopic fundus camera capable of easily synthesizing a plurality of images.

[Prior Art] Conventionally, as a method of obtaining a stereoscopic image by synthesizing a plurality of fundus images, a method of extracting and matching the same feature points such as blood vessels using an image processing device is known.

However, there are drawbacks that the apparatus becomes complicated and that accurate matching of a plurality of images is difficult.

Therefore, in order to compensate for this drawback, a fixation target (fixation index) for the subject to fixate is imprinted in the image, and an image is synthesized based on the fixation target. 17
No. 0438 discloses this. According to this apparatus, since the fixation target is used as the synthesis reference, there is only one synthesis reference.

[Problems to be solved by the present invention] However, it is insufficient to combine two images by one reference point as in the above-described device. That is, although one point on the image can be accurately matched by the synthesis reference point, since each image has a degree of freedom in rotation, it is necessary to extract another feature point of the image by another method. It had the disadvantage of not having to.

It is an object of the present invention to provide a simultaneous stereoscopic fundus camera that can accurately and easily combine a pair of stereo images captured by the stereoscopic fundus camera.

Means for Solving the Problems To achieve the above object, the present invention provides an illumination optical system for illuminating a fundus of a subject's eye, an imaging optical system for photographing the fundus of the subject's eye, and a fundus of the subject's eye. In a stereoscopic fundus camera having an observation optical system for observing, in order to be a reference for synthesizing a stereo image, an image synthesizing index plate for projecting a plurality of indices to the fundus, and the refractive power of the eye to be inspected. Moving means for moving the image combining index plate along the optical axis so as to correct the image combining index plate, and maintaining a constant projection magnification of the image combining index on the fundus irrespective of the movement of the image combining index plate. And a projection optical system.

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

(Structure) FIG. 1 is a schematic layout diagram of an optical system when an embodiment of the present invention is viewed from the side, and includes an illumination optical system, a photographing optical system, an observation optical system, and a target projection system including a fixation target. Become. Figure 2 shows the first
It is the figure which looked at the optical system of the figure from the top.

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. The halogen lamp 1 and the xenon flash lamp 3 are conjugate to the condenser lens 2.

4 is a beam splitter, 5 is a relay lens, and 6 is an aperture stop. 7 is a mirror for changing the optical path, 8 is an illumination relay lens, 9 is an illumination stop, 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. The two-aperture stop 15 is arranged so as to be conjugate with the pupil of the eye to be examined and the objective lens 13, and divides the light beam into two by this stop. 16, 17
Is a light beam splitting prism, and the light beam splitting prism 16 is for exchanging the left and right of the bisected light beam. The light beam splitting prism 17 separates the light beam.

The light beam reflected by the fundus of the eye to be examined
After forming an inverted intermediate image at a point, the light passes through the aperture of the perforated mirror 12, passes through the two-hole aperture 15, and the light beam splitting prisms 16 and 17, and then relays a lens 18, a focusing lens 19 and an imaging lens 21. To form a fundus image on the film surface 22. The focusing lens 19 is movable in the optical axis direction.

Reference numeral 20 denotes a flip-up mirror, which switches the optical paths of the photographing optical system and the observation optical system. The flip-up mirror 20 is synchronized with the light emission of the xenon flash lamp 3, and simultaneously with the light emission of the lamp 3, the flip-up mirror 20 is flipped up in the direction of the arrow, and The luminous flux is guided to the film surface.

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 spring-up mirror 20.

The reflected light from the fundus guided through the objective lens 13 to the focusing lens 19 is reflected by the flip-up mirror 20, and then changes the optical path by the mirror 23. The photographer 27 observes the fundus image of the subject's eye via the observation system imaging lens 24, the eyepiece field stop 25, and the eyepiece 26.

The index optical systems 31, 32, 33 and 34 (not shown) are light sources for projecting the mask 35. The mask 35 is configured as shown in FIG. 35a and 35b are image combining indices for aiming at the time of image combining, and 35c and d are fixation indices for the subject to fixate, which are for the left eye and the right eye. The image combining indices 35a and 35b are projected by the light sources 31 and 32,
35c and 35d are projected by the light sources 33 and 34, and are used by switching and lighting the light sources 33 and 34. Instead of switching on and off the light sources 33 and 34, a mask may be provided to present one of the fixation indices 35c and 35d to the subject.

The mask 35 moves in the optical axis direction in conjunction with the focusing lens 19 for correcting the refraction state of the eye to be inspected.

Reference numeral 36 denotes an auxiliary lens, which is arranged so that the angles of the fixation target and the image combining target that enter the subject's eye do not change even when the mask 35 moves in the optical axis direction. That is, in this embodiment, the auxiliary lens 36 and the illumination system relay lens 1
1. The objective lens 13 constitutes a Badal optical system, and the combined focal point of these is set to be substantially at the pupil position.

FIG. 4 is a view showing the field of view when the subject looks at the objective lens 13.

Reference numeral 40 denotes an outer frame of the objective lens 13, and reference numeral 41 denotes an illumination area limited by the illumination stop 9. Reference numerals 42 and 43 are image synthesis indices, 44 is a left-eye fixation index, 45 is a right-eye fixation index, and the left-eye fixation index 44 and the right-eye fixation index 45 are selected as described above. Presented in a unified manner. The fixation indices 44 and 45 are arranged at a position of 15 ° left and right and 2 ° below, and at this time, the nipple can be brought to the center of the screen (see FIG. 5).

Also, the image combining indices 42 and 43 are arranged at positions 10 ° above and below, and the interval between them is set to 20 °.

Such a configuration of the mask is an example set for imaging mainly the nipple, and may be changed as needed.

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

The optical system main body housed in the casing has a sliding mechanism composed of a movable table on which it is mounted and a fixed table that moves relative to the movable table, and fixes the subject to the jaw table fixed to the fixed table,
The user is instructed to gaze at the fixation index inside the apparatus.

When the examiner intends to photograph the right eye, the examiner presses a right-eye photographing switch (not shown) and turns on the right-eye light source 35d.

Thereafter, the halogen lamp 1, which is a light source for observation, is turned on to illuminate the eye to be examined. The photographer operates the sliding mechanism with the joystick to move the image on the cornea of the aperture stop 6 of the illumination system and the pupil of the subject's eye by moving the optical system right and left and up and down to perform alignment. When the alignment is almost completed, the illumination light illuminates the fundus.

The reflected light from the fundus forms an intermediate image after passing through the objective lens. This fundus image is an inverted image. Then perforated mirror
After passing through 12, the light beam is split into two right and left light beams by a two-hole stop 15. Next, the right and left light beams are switched and separated by the light beam splitting prism 16 immediately after the two-hole stop 15. After the separated light beams are reflected by the prisms 17a and 17b, respectively, the field stop of the eyepiece is formed by a pair of imaging lens systems, namely, relay lenses 18a and b, focusing lenses 19a and b, and observation imaging lenses 24a and 24b. Image on 25a, b. This fundus image is an erect image. By observing this image, the photographer can perform stereoscopic observation of the fundus. The photographer observes the left and right images and turns the knobs linked to the focus lenses 19a and 19b to focus on the best focus position, and at the same time, finely adjusts the alignment so that flare does not appear on the left and right.

When the alignment and focusing are completed and the shooting button is pressed, the xenon flash lamp 3 emits light. When the xenon flash lamp 3 emits light, the flip-up mirror 20 in the photographing system rises in synchronization with the light emission, and a photograph is taken on the film surface.

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

The fundus image photographed in this manner is a pair of stereo images as shown in FIG. On one frame of the film 22, an image 22a from the optical path a, an image 22b from the optical path b, and an image combining index are imprinted. Therefore, by combining the imprinted index for image synthesis as a reference, one stereoscopic photograph 22c can be easily synthesized from the stereo images 22a and 22b.

[Effects of the Invention] According to the present invention, a plurality of indices for synthesis are imprinted on a pair of stereo images of a stereoscopic fundus camera, so that a plurality of images can be easily and accurately matched.

Further, in the case of a projection system in which the angle of the image combining index incident on the eye to be examined does not change, the angular interval of the plurality of imprinted indexes is constant irrespective of the refraction state of the eye to be examined. It can be used as a scale at the time.

[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, FIG. 2 is a diagram of the optical system of FIG. 1 viewed from above, FIG. FIG. 4 shows that the subject has an objective lens.
FIG. 5 is a diagram showing a field of view when the user looks at 13, and FIG. 5 is a diagram for explaining an operation of synthesizing a stereoscopic photograph from a pair of stereo images. 6 ... Aperture stop, 11 ... Relay lens for illumination system 12 ... Perforated mirror, 13 ... Objective lens 31, 32, 33, 34 ... Light source for mask projection 35 ... Mask, 36 ... Auxiliary lens

Claims (1)

(57) [Claims] 1. A stereoscopic fundus having an illumination optical system for illuminating the fundus of the eye to be examined, a photographing optical system for photographing the fundus of the eye to be examined, and an observation optical system for observing the fundus of the eye to be examined. In the camera, an image synthesizing index plate for projecting a plurality of indices to the fundus and a first image synthesizing index plate for correcting the refractive power of the eye to be examined are used as a reference for synthesizing a stereo image. Means of movement along the
A stereoscopic fundus camera, comprising: a projection optical system that maintains a constant projection magnification of the image combining index on the fundus irrespective of movement of the image combining index plate.