JP3897643B2 - Ophthalmic imaging equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ophthalmologic photographing apparatus used in an ophthalmic clinic or the like.
[0002]
[Prior art]
In the conventional illumination optical system of the fundus camera, in order to separate the imaging light beam and the illumination light beam in the vicinity of the anterior eye portion of the eye to be examined, an optical axis that forms an image near the eye pupil of the eye to be examined and further, for example, near the rear surface of the crystalline lens before and after that Is provided with a light-shielding stop having a light-shielding region and a ring-shaped opening.
[0003]
Therefore, when the pupil diameter of the subject is larger than the light shielding area, an image with appropriate brightness can be obtained. However, for the subject whose pupil diameter is smaller than the light shielding area, the illumination light flux is limited by the iris. Therefore, since the vicinity of the center of the fundus image becomes dark, a light-shielding stop having a different size is provided, and when photographing an eye to be inspected with a small pupil diameter, the image is exchanged with a light-shielding stop having a small light-shielding area.
[0004]
[Problems to be solved by the invention]
However, in the above-described conventional example, by reducing the size of the light-shielding stop, the light beam separation range is reduced, so that flare occurs around the fundus image and the image quality of the peripheral portion is degraded. Another problem is that the fundus findings cannot be obtained due to the shadow of the flare.
[0005]
An object of the present invention is to provide an ophthalmologic photographing apparatus capable of solving the above-described problems and capable of photographing even a subject having a small pupil diameter.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 is directed to a light shielding means for exchanging a plurality of apertures having light shielding regions of different areas and conjugated with the vicinity of the anterior eye portion to be examined , A fundus illuminating unit that illuminates the fundus of the subject's eye through the diaphragm inserted by the light shielding unit, an imaging unit that captures a plurality of images corresponding to the light shielding unit, and obtains a plurality of images; An ophthalmologic photographing apparatus comprising an image compositing means for composing one image from one image.
[0007]
According to a second aspect of the present invention, there is provided a first light-shielding aperture which is a ring-shaped opening having a first light-shielding region around the optical axis, projected near the rear surface of the eye lens to be examined, and the first light-shielding region. A second light-shielding aperture having a smaller second light-shielding region, an image of a peripheral portion of an image photographed using the first light-shielding aperture, and an image of a central portion of an image photographed using the second light-shielding aperture. An ophthalmologic photographing apparatus comprising image processing means for combining and combining one image.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail based on the illustrated embodiment.
FIG. 1 is a configuration diagram of a fundus camera according to an embodiment. In front of an eye E, an aperture lens 3 having an objective lens 1 and a photographing aperture 2, a focus lens 4, a photographing lens 5, and a color separation prism 6 are shown. The image pickup mechanisms including the image pickup elements 7r, 7g, and 7b are sequentially arranged.
[0009]
In the fundus illumination system in the incident direction of the perforated mirror 3, the cornea stop 8 having a ring-shaped opening having a light shielding means in the area around the optical axis projected from the perforated mirror 3 side to the vicinity of the cornea, the relay lens 9, and the optical path is inserted. An infrared light cut filter 10 that is detachable and cuts infrared light, and has a ring-shaped opening having a large light shielding area as shown in FIG. A first lens aperture 11a that can be inserted into and removed from the optical path; a second lens aperture 11b that has a smaller light-shielding area around the optical axis than the first lens aperture 11a as shown in FIG. A ring stop 12 having a ring-shaped aperture that is conjugate with the vicinity of the pupil of the eye E, an imaging light source 13 composed of a strobe tube, a condenser lens 14, and an observation light source 15 such as a halogen lamp that emits steady light are sequentially arranged. .
[0010]
The outputs of the image sensors 7r, 7g, and 7b are connected to the image boards 17r, 17g, and 17b via the signal amplification circuits 16r, 16g, and 16b for red, green, and blue signals. The image boards 17r, 17g, and 17b are composed of A / D converters 18r, 18g, and 18b, and memories 19r, 19g, and 19b. The output of the image boards 17r, 17g, and 17b is an image control that includes the image memory 20a. Connected to means 20.
[0011]
The image control means 20 is connected to the control means 21, the image recording means 22, and the television monitor 23. The image recording means 22 is a non-volatile recording medium such as MO, MD, DVD-RAM, VTR tape, memory card, hard disk or the like. D is a drive device that writes to or reads from D.
[0012]
An imaging switch 24 and a small pupil diameter switch 25 are connected to the control means 21, and an output of the control means 21 is connected to the imaging light source 13 via a strobe light emission control circuit 26. In the control means 21, a memory 21a and a strobe light emission control circuit 26 are provided with a first capacitor 26a and a second capacitor 26b for controlling the amount of emitted light.
[0013]
When photographing the fundus using this fundus camera, the pupil is measured using a pupil meter, or the pupil diameter of the eye E is observed by an anterior ocular segment observation means (not shown), and the pupil diameter of the subject is predetermined. If the size is smaller than 4 mm, for example, the small pupil diameter photographing mode is set by operating the small pupil switch 25. In the fundus observation state, even when the fundus central part is dark, it may be determined that the pupil diameter of the eye E is small, and the small pupil diameter photographing mode may be set.
[0014]
If the pupil diameter is sufficiently wide as shown in FIG. 4, that is, if the iris Ep is wide open with respect to the illumination light beam, the center of the fundus Er can be illuminated well, but the iris Ep is narrow as shown in FIG. 5. If the pupil diameter is small, the iris Ep blocks the illumination light beam indicated by the broken line, so that the central part of the fundus Er cannot be illuminated. Therefore, by exchanging the first crystalline lens stop 11a with the second crystalline lens stop 11b having a small light shielding area near the optical axis, conjugate images 11a ′ and 11b ′ of these diaphragms 11a and 11b are respectively shown in FIGS. Thus, the illumination light beam can illuminate the center of the fundus Er as indicated by the solid line.
[0015]
FIG. 6 is a flowchart showing a schematic photographing procedure for synthesizing two images to obtain an image having no defect. First, photographing is started by operating the photographing switch 24 in step S1, and the first in step S2. A first fundus image is taken using the lens aperture 11a. As step S3, the first fundus image taken in step S2 is recorded in the image memory 20a.
[0016]
Subsequently, a second fundus image is photographed using the second lens diaphragm 11b as step S4, and the second fundus image photographed at step S4 is recorded in the image memory 20a as step S5. Further, in step S6, the peripheral image of the first fundus image and the center image of the second fundus image are synthesized. In step S7, the fundus image synthesized in step S6 is subjected to distortion correction and smoothing processing, and in step S8, the final image is recorded and displayed.
[0017]
Next, the imaging procedure will be described in more detail. First, the subject performs alignment between the eye E and the fundus camera while observing the fundus Er of the eye E with infrared light. In this observation state, the infrared light cut filter 10 is separated from the optical path, and the first lens diaphragm 11a is inserted.
[0018]
Infrared light emitted from the observation light source 15 is collected by the condenser lens 14, passes through the apertures of the imaging light source 13 and the ring diaphragm 12, passes through the apertures of the lens 9 and the corneal diaphragm 8, and surrounds the perforated mirror 3. Reflected leftward by the mirror unit, the fundus Er is illuminated through the objective lens 1 and the pupil Ep.
[0019]
In this way, the image of the fundus Er illuminated with infrared light again passes through the objective lens 1, the photographing aperture 2, the focus lens 4, and the photographing lens 5 and enters the color separation prism 6. The color separation prism 6 guides infrared light and red light to the image pickup device 7r, blue light to the image pickup device 7b, and green light to the image pickup device 7g. However, since the observation light is infrared light, it is connected to the image pickup device 7r. Image and converted into an electrical signal. These signals are amplified by a signal amplification circuit 16 with a predetermined amplification factor for observation, input to the image board 17r and the image control means 20, and displayed on the television monitor 23.
[0020]
A photographer who observes this image and determines that the center of the image is dark as described above operates the small pupil diameter photographing switch 25. The photographer who observes the image displayed on the television monitor 23 and confirms that the preparation for photographing is complete operates the photographing switch 24. The control means 21 that has detected the input from the photographing switch 24 inserts the infrared light cut filter 10 in the optical path, and the strobe light emission control circuit 26 discharges the charge of the first capacitor 26 a to emit the photographing light source 13. The light emitted from the imaging light source 13 passes through the ring-shaped opening of the ring diaphragm 12 and the ring-shaped opening of the first crystalline lens diaphragm 11 a, and only visible light is transmitted by the infrared light cut filter 10 and passes through the relay lens 9. Reflected leftward by the mirror part around the perforated mirror 3, and illuminates the fundus Er through the objective lens 1 and the pupil Ep.
[0021]
The illuminated image of the fundus Er passes again through the objective lens 1, the photographing aperture 2, the focus lens 4, and the photographing lens 5, enters the color separation prism 6 and is separated into the respective colors, and the image pickup devices 7r, 7g, Each image is formed on 7b and converted into an electric signal. These signals are amplified at a predetermined amplification rate through the signal amplification circuits 16r, 16g, and 16b, and converted into digital image data by the A / D conversion units 18r, 18g, and 18b of the image boards 17r, 17g, and 17b. After that, it is input to the image control means 20, stored as the first fundus image A in the image memory 20 a, and a recording completion signal is transmitted to the control means 21.
[0022]
In the case of normal shooting, the shooting is ended. In the case of the small pupil diameter shooting mode, the following operation is further performed. The control means 21 that has detected the recording completion signal changes the first lens aperture 11a to the second lens aperture 11b, and emits the strobe light source 13 by the electric charge accumulated in the second capacitor 26b. Compared with the first capacitor 26a, the second capacitor 26b accumulates a large charge and emits light with a large amount of light. Similarly, the light emitted from the strobe light source 13 illuminates the fundus Er of the eye E.
[0023]
Similarly, the illuminated fundus image is incident on the color separation prism 6 to be separated into each color, imaged on the image sensors 7r, 7g, and 7b, converted into electric signals, and the signal amplification circuits 16r, 16g, 16b is amplified at a predetermined amplification factor, converted into digital image data by the A / D converters 18r, 18g, and 18b, input to the image control means 20, and stored in the image memory 20a as the second fundus image B. Remembered. The image control means 20 synthesizes one fundus image from the two photographed fundus images A and B.
[0024]
FIG. 7 shows a procedure for synthesizing two fundus images. A dark region A ′ is photographed at the center of the first fundus image A. This is because the pupil diameter of the subject was small, and the light beam that illuminates the center of the fundus was blocked by the iris and the first crystalline lens stop 11a. Flare light enters the peripheral portion of the second fundus image B photographed using the second crystalline lens stop 11b, and a region B ′ that cannot be interpreted by the fundus image is photographed.
[0025]
The image control unit 20 cuts out a portion larger than ½ of the radius r of the image from the first fundus image A, for example, and creates an image C. Further, an image D is created by cutting out an image of a portion smaller than ½ of the radius r of the image from the second fundus image B. Subsequently, the image E is synthesized by pasting these images C and D together.
[0026]
The two fundus images A and B are images taken continuously within a short period of time, so there is almost no shift in the images when pasting them together, but there is a slight shift due to the effects of fixational movement, etc. Therefore, it is possible to correct the image using a pattern matching method at the boundary part of the pasting, smoothing processing, image density correction, image distortion correction, etc. The performed final image is recorded on the recording medium D by the image recording means 22 and the image is displayed on the television monitor 23. Needless to say, when performing the pasting process, it is easier to process images C and D by providing a slight overlap.
[0027]
Further, in the present embodiment, an example has been described in which the first lens aperture 11a is replaced with the second lens aperture 11b for imaging, but by providing a smaller third lens aperture, an even smaller pupil is provided. It is also possible to correspond to the diameter.
[0028]
【The invention's effect】
As described above, the ophthalmologic photographing apparatus according to the present invention performs photographing with a single aperture operation using different aperture stops, and combines the respective images to synthesize a single fundus image. Since an image with a wide angle of view can be obtained even for a subject having a small diameter, the efficiency of fundus imaging is improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fundus camera.
FIG. 2 is a front view of a first lens diaphragm.
FIG. 3 is a front view of a second lens diaphragm.
FIG. 4 is an explanatory diagram of an optical path of a relationship between an eye to be examined and an illumination light beam when a diaphragm with a large light shielding area is used.
FIG. 5 is an explanatory diagram of an optical path of a relationship between an eye to be examined and an illumination light beam when a diaphragm with a small light shielding area is used.
FIG. 6 is a flowchart of a photographing procedure.
FIG. 7 is an explanatory diagram of image composition.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Objective lens 2 Imaging aperture 3 Perforated mirror 4 Focusing lens 5 Imaging lens 6 Color division prism 7 Imaging element 8 Corneal aperture 9 Relay lens 10 Infrared light cut filters 11a and 11b Crystal diaphragm 13 Imaging light source 14 Lens 15 Observation light source 16 Amplification Circuit 17 Image board 18 A / D converter 19 Memory 20 Image control means 21 Control means 22 Image recording means 23 Television monitor 24 Shooting switch 25 Small pupil photographing switch 26 Strobe light emission control circuit

Claims (2)

A light- shielding means for exchanging a plurality of diaphragms having light-shielding areas of different areas and conjugated with the vicinity of the anterior eye portion of the eye to be examined, and the eye to be examined via a diaphragm inserted by the light-shielding means among the plurality of diaphragms A fundus illuminating unit that illuminates the fundus, an imaging unit that captures a plurality of images corresponding to the light shielding unit, and obtains a plurality of images; and an image synthesis unit that synthesizes one image from the plurality of images. An ophthalmologic photographing apparatus comprising:   A first light-shielding aperture that is a ring-shaped opening having a first light-shielding area around the optical axis and a second light-shielding area that is smaller than the first light-shielding area is projected near the rear surface of the subject eye lens. And a central portion of an image photographed using the second light-shielding aperture, and a single image is composed. An ophthalmologic photographing apparatus comprising: an image processing unit.

Images