JP3164233B2 - Stereoscopic fundus camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereoscopic fundus camera,
In particular, the present invention relates to an apparatus for detecting a focus position of a stereoscopic fundus camera.

[0002]

2. Description of the Related Art A conventional stereoscopic fundus camera focuses by superimposing a linear reticle disposed on an observation system with an aerial image of the fundus and observing the image formation state. Japanese Patent Publication No. 57-13294 discloses a general-purpose fundus camera that focuses on a subject (foreground).
A mechanism has been proposed in which a plurality of luminous fluxes, which jointly form an index image for detecting a scum position), are projected onto the fundus, and the separated state of the index image reflected on the fundus is observed with a direct-view finder system.

[0003]

However, in the former case, since the diopter of the observer directly affects the observation state,
It is necessary to strictly adjust the diopter of the viewfinder,
Accurate focusing has the disadvantage of requiring considerable skill. When the latter mechanism is used for a stereoscopic fundus camera, the stereoscopic fundus camera views two images on the left and right. If the observer does not converge, the index images separated into a plurality appear to be further separated, and the There is a drawback that it is difficult to match. A stereoscopic fundus camera is also expected to perform a stereoscopic examination by detailed fundus observation with a direct-view finder, but the latter mechanism has a disadvantage that a fundus image and a focus index overlap and a part of the fundus cannot be seen.

[0004] A first object of the present invention is to provide a stereoscopic fundus camera that can be easily focused by anyone. A second object is to provide a three-dimensional fundus camera capable of observing a fundus in detail by a direct-view finder or the like without a shadow of the index projection system appearing.

[0005]

In order to achieve the above object, a stereoscopic fundus camera according to the present invention has the following features. (1) A stereoscopic fundus camera that divides a reflected light beam from the fundus into two light beams, provides an imaging optical system in the optical path of each of the divided light beams, and performs stereoscopic observation and stereoscopic photographing of the fundus.
The eye to be inspected and the imaging optical system have a predetermined positional relationship.
Alignment mechanism for focusing on the subject, a focusing lens for focusing on the fundus of the subject's eye, and imaging
An index placed at a position conjugate to the plane, and is transmitted through an imaging optical system on either the left or right side of the image on the focusing lens.
A focus target where the target image is projected onto the fundus , and another focus optical system different from the focus optical system provided with the focus target .
And a photodetector located at a position diverged from the imaging surface and arranged at a position conjugate with the imaging plane.

(2) In the stereoscopic fundus camera according to the first aspect, the focus index and the photodetector are branched from the imaging optical path.
A hot mirror that reflects infrared light obliquely placed on the observation optical path
And projected or branched to the fundus through the eye .

[0007]

[0008]

[0009]

[0010]

[0011]

[0012]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an optical system layout when an embodiment of the present invention is viewed from the side, and FIG. 2 is a diagram of the optical system of FIG. 1 viewed from above.

[Configuration] The main optical system of the apparatus of this embodiment is an illumination optical system, a photographing optical system, an observation optical system,
It consists of a scum detection optical system.

(Illumination optical system) 1 is a halogen lamp which is a light source for observation, 2 is a condenser lens, and 3 is a xenon flash lamp which is a light source for photographing. The halogen lamp 1 and the xenon flash lamp 3 are conjugate with respect 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 a relay lens for an illumination system, 9 is a sign plate having a black spot at the center for removing harmful light, 11
Is an illumination relay lens, and 12 is a perforated mirror. The aperture stop 6 is formed of a ring-shaped slit. An intermediate image of the slit is formed in the vicinity of the opening of the perforated mirror 12, reflected by the perforated mirror 12, and then slit near the cornea by the objective lens 13. An image is formed and the fundus of the eye 14 is illuminated.

(Shooting optical system) 13 is an objective lens, and 15 is a two-hole stop. The two-hole stop 15 is disposed so as to be conjugate with the pupil of the eye to be inspected and the objective lens 13, and divides the light beam into two by this stop. Reference numerals 16 and 17 denote light beam splitting prisms, and the light beam splitting prism 17 makes the split light beams parallel at predetermined intervals. The luminous flux reflected from the fundus of the eye to be examined forms an inverted intermediate image at the point A by the objective lens 13 and then passes through the aperture of the perforated mirror 12 and passes through the two-hole aperture 15 and the luminous flux separating prisms 16 and 17. After that, the relay lens 1
8. A fundus image is formed on the film surface 22 by the focusing lens 19 and the imaging lens 21. 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 22. Reference numeral 20 denotes a flip-up mirror, which switches the optical paths of the photographing optical system and the observation optical system, and is synchronized with the light emission of the xenon flash lamp 3, and the lamp 3 emits light simultaneously with the flip-up mirror 20 being flipped in the direction of the arrow. Then, the luminous flux from the fundus is guided to the film surface.

(Observation Optical System) The observation optical system is an objective lens 1
It is shared with the optical system of the photographing optical system of the mirrors 3 through 20. The observation light reflected by the fundus and transmitted through the objective lens 13 through the focusing lens 19 is reflected by the flip-up mirror 20, and then the optical path is changed by the mirror 23. The photographer 27 observes the fundus image of the eye via the observation system imaging lens 24, the ocular field stop (not shown), and the ocular lens 26.

(Focus detection optical system) The focus detection optical system is composed of an index projection system and an index detection system. One of the left and right observation optical systems (photographing optical system) has an index projection system and the other has an index projection system. A detection system is provided. Reference numerals 31a and 31b denote infrared LEDs which are light sources of the index projection system. The infrared LEDs 31a and 31b are arranged at positions substantially symmetric with respect to the optical axis. Reference numeral 32 denotes a pinhole, reference numeral 33 denotes a relay lens, and reference numeral 34 denotes a hot mirror which reflects infrared light and transmits visible light. The index detection system is configured as follows. A hot mirror 35 has the same spectral characteristics as that of the hot mirror 34. 36
Is a relay lens, and 37 is a two-divided light receiving element. 38
Is a visible LED for displaying a focus state based on the detection result of the light receiving element 37.

[Operation] The operation of the apparatus of the embodiment having the above-described optical system will be described. The optical system main body housed in the casing is mounted on a movable table, and is moved relative to a fixed table by a sliding mechanism. The subject is fixed to a jaw table fixed to a fixed table, and the halogen lamp 1 serving as an observation light source is turned on to illuminate the eye to be examined. The photographer operates the joystick and moves the optical system left, right, up and down via the sliding mechanism,
Alignment is performed so that the image of the aperture stop 6 of the illumination system on the cornea and the pupil of the eye to be examined have a predetermined positional relationship. When the alignment is almost completed, the illumination light illuminates the fundus. The fundus reflection light of the illumination light forms an intermediate image of the fundus after passing through the objective lens 13. This fundus image is an inverted image. Perforated mirror
The light beam that has passed through 12 is split by a two-hole aperture 15 into two light beams on the left and right. The split luminous flux is separated by exchanging the left and right luminous flux by the luminous flux separating prism 16 immediately after the two-hole aperture 15. After the separated light beams are reflected by the prisms 17a and 17b, the eyepieces are formed by a pair of imaging lens systems, namely, relay lenses 18a and 18b, focusing lenses 19a and 19b, and observation system imaging lenses 24a and 24b. An image is formed on the field stop of the lens. This fundus image is an erect image. By observing this image, the photographer can perform stereoscopic observation of the fundus.

Next, while observing the left and right images, the photographer turns the knob to move the focusing lenses 19a, b to the position where the best focus can be obtained, and at the same time, the flare caused by the illumination light is changed to the left and right. Fine-tune the alignment so that it does not appear in the image. The moving position of the focusing lenses 19a and 19b is determined using a focus detection optical system as follows. The light beam emitted from the pair of infrared LEDs 31a and 31b and passed through the pinhole 32 passes through the relay lens 33, and becomes coaxial with the observation system by the hot mirror 34.
The pinhole 32 is projected onto the fundus through the solid-line optical path via the objective lens 13. The fundus reflection light of the pinhole image passes through the optical path indicated by the broken line of the objective lens 13 and becomes coaxial with another observation system different from the observation system in which the index projection system is arranged, and then reflected by the hot mirror 35. . And the relay
After passing through the lens 36, an image is formed on the two-divided light receiving element 37.

When the focusing lenses 19a and b are moved, the focus is in the best state when the pinhole 32 and the fundus are in a conjugate positional relationship. When the focus shifts, the pinhole image projected on the fundus is gradually separated into two while being blurred. Since the pinhole image of the fundus is also separated, the pinhole image on the two-divided light receiving element 37 is also separated (FIG. 3A). At this time, since the balance of the amount of light incident on each of the light receiving elements 37a and 37b of the two-part light receiving element 37 has been lost, the focusing lens is moved in the direction in which the amounts of light incident on both elements become equal to adjust the focus. .
Then, when the pinhole images coincide, the light amounts on the light receiving elements become equal (FIG. 3B). When the focus lens is further moved, the pinhole image is split into two again,
The light amount balance between the respective light receiving elements is also lost. Therefore, FIG.
If the position b is detected, the best focus position can be detected. The signals of the two-divided light receiving element 37 are compared by a processing circuit (FIG. 4), and when the light amount balance is equal to or more than a certain value, the microcomputer 39 in the apparatus is set to L level.
By driving the ED drive circuit 40 to turn on the LED 38 in the eyepiece, the photographer is informed of the best focus position. As described above, the photographer can accurately focus on the fundus. When the alignment and focusing are completed and the photographing button is pressed, the flip-up mirror 20 in the photographing system jumps up in synchronization with this and the xenon flash lamp 3 emits light. When the xenon flash lamp 3 emits light, a fundus image is captured on the film surface.
The above operation is controlled by a microcomputer 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. In this embodiment, the LED 38 is turned on when the light amount balance is matched.
The moving direction (movement amount) of the lens may be displayed. The observation system may be performed by a TV monitor.

[0021]

Embodiment 2 This embodiment is an apparatus in which focusing is automated in the above embodiment. FIG. 6 is a block diagram showing this control method. When a focus shift is detected by the two-divided light receiving element 37, the signal is sent to the microcomputer 39 via the processing circuit, and the microcomputer 39 receiving the signal receives the signal via the driving circuit 41. By controlling the single lens driving unit 42, the focusing lenses 19a and 19b are moved in the direction in which the amount of incident light becomes equal,
It is stopped at a position where a predetermined light amount balance is reached. Fore
Upon receiving the cutting completion signal, the photographing switch is turned on, and photographing is performed.

[0022]

According to the present invention, since the light projecting system and the light receiving system of the focus detecting system can be separated into different optical paths, the influence on the light receiving system due to reflection inside the optical system can be avoided. Because it is built into the observation and photography system,
Since the cas lens can be shared and the detection system can be operated in all the focus ranges, there is an effect that highly accurate focus detection can be performed in a wide focus range.

[Brief description of the drawings]

FIG. 1 is an arrangement diagram of an optical system of a first embodiment when viewed from a side.

FIG. 2 is an arrangement diagram when the optical system of the apparatus according to the first embodiment is viewed from above.

3A and 3B are diagrams showing a state of a pinhole image on a two-divided light receiving element, wherein FIG. 3A shows a blurred state, and FIG. 3B shows a state where the pinhole images match.

FIG. 4 is a block diagram illustrating a signal processing circuit of a two-segment light receiving element according to the first embodiment.

FIG. 5 is a diagram showing a photographed fundus image.

FIG. 6 is a block diagram illustrating a signal processing circuit of a two-segment light receiving element according to a second embodiment.

[Explanation of symbols]

 19a, b Focusing lens 31a, b, 38 LED 32 Pinhole 33, 36 Relay lens 34, 35 Hot mirror 37 Two-part light receiving element 39 Microcomputer 40 LED drive circuit 42 Focusing lens drive Department

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) A61B 3/00-3/16

Claims (2)

(57) [Claims] 1. A light beam reflected from a fundus is divided into two light beams,
An imaging optical system is provided in each of the optical paths of the divided light beams ,
In a stereoscopic fundus camera that performs stereoscopic observation and stereoscopic photography of the fundus, the eye to be inspected and the imaging optical system have a predetermined positional relationship.
Mechanism, a focusing lens for focusing on the fundus of the eye to be inspected , and indices arranged at a position conjugate with the photographing surface, and the left and right on the image side of the focusing lens Any imaging optics
The focus index, where the index image is projected onto the fundus, is located at a position diverged from the other imaging optical system different from the imaging optical system provided with the focus index, and at a position conjugate with the imaging surface. A stereoscopic fundus camera, comprising: a photodetector arranged. 2. The stereoscopic fundus camera according to claim 1, wherein the focus indicator and the photodetector are observation light branched from a photographing optical path.
Via a hot mirror that reflects infrared light obliquely installed on the road
A stereoscopic fundus camera, which is projected or branched to the fundus.