JP2000116602A - Retinal camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve an accurate adjustment of focus with a simple structure by projecting a target for focusing onto the eyegrounds and imaging a retinal reflection image to detect the blurring of a target image. SOLUTION: Reflected light from an eyground travels on an optical path 03 of an observation imaging system to form an image of a pupil P near a bored mirror 8 with an objective lens 15 and passes through a hole part of the bored mirror 8 and a turret 16 to form an image by an imaging lens 17 again near a field lens 18. Further, the light passes through a collimator lens 19 to form a retinal image onto an imaging means 21 for observation imaging with an imaging lens 20. The resulting image is displayed on a TV monitor 24 and an image signal is stored into a memory 23. Here, a general purpose camera 25 encircled by a dotted line detects the blurring of the image of the imaging means 21 by an automatically focusing function and moves a part of the imaging lens 20 in the direction of the optical path 03 to accomplish automatic focusing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera used in an ophthalmic hospital or the like.

[0002]

2. Description of the Related Art Conventionally, in a fundus camera, a focus detection system and a fundus photographing system are separately provided, and a focusing light beam is projected onto the fundus using an incandescent lamp having a wavelength width, and the fundus is projected. The position of the reflected image is detected by the focus sensor. In addition, a retinal camera that projects a focusing light beam onto the fundus via a light splitting member provided in the fundus illumination system and moves the focusing light beam projection system together with the light splitting member, or a near-perforated mirror is provided. 2. Description of the Related Art A fundus camera that projects a light beam for focusing via a small mirror and links a part of the light beam projection system for focusing with a focusing lens for fundus photographing to perform focusing is known. Furthermore, a part of the pupil of the subject's eye projects a focusing target onto the fundus to detect its image position, and then moves the focusing light beam projection system to focus, and a diopter near the perforated mirror. There is also known a fundus camera that manually moves a correction lens in and out.

[0003]

However, in the above-mentioned conventional example, in the apparatus for projecting a light beam from the fixed focusing light beam projection system, accurate focusing is performed because the image is focused at a blurred image position. In a device that moves the focusing light beam projection system to perform focusing, there is a pupil conjugate point outside the driving range of the focusing lens. However, there is a problem that the size of the movable part is large, the configuration is complicated, and the operation is complicated.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a fundus camera capable of performing high-precision focusing with a simple configuration.

Another object of the present invention is to provide a fundus camera with improved operability for diopter correction.

It is still another object of the present invention to provide a fundus camera capable of using a small-diameter imaging lens and a general-purpose digital camera by reducing the fluctuation of the pupil conjugate position due to focusing.

It is still another object of the present invention to provide a fundus camera which projects a focusing light beam onto the fundus without restricting the light beam of the fundus illumination system.

[0008]

A fundus camera according to the present invention for achieving the above object has a fundus photographing system for photographing a fundus image by imaging means, and a fundus reflection image formed by projecting a focusing target onto the fundus. And a focus detection system for detecting and focusing by the imaging means.

A fundus camera according to the present invention is a fundus camera for dividing a fundus observation illumination optical path and a fundus photographing optical path at a pupil conjugate position of an objective lens, wherein a fixed light dividing member provided on the fundus observation illumination optical path; A focusing light beam projection system that projects the focusing light beam onto the fundus so as to be able to focus through the light splitting member; and a focusing unit of a fundus photographing system. The operation and the focusing operation of the fundus imaging system are interlocked.

A fundus camera according to the present invention is characterized in that a target is projected on the fundus by laser light condensed on the anterior segment, and a focusing operation is performed by a fundus reflection image of the target.

The fundus camera according to the present invention is characterized in that the power of the diopter correction lens provided at the conjugate position of the subject's eye is changed based on the focus detection signal.

A fundus camera according to the present invention has a lens for forming a fundus image by an objective lens, and an imaging lens system for forming the fundus image on an image pickup means. It is characterized by being conjugated in a lens system, and performing a focusing operation by the imaging lens system.

A fundus camera according to the present invention has a fundus illumination system for uniformly illuminating the fundus, and the fundus illumination system includes a light dividing member for selectively dividing wavelength light of a focusing light beam by laser light. It is characterized by having been provided.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 shows a configuration diagram of an optical system of the fundus camera according to the first embodiment. On the optical path O1 of the illumination optical system for fundus observation and photography, an observation lamp light source 1, a lens 2, a light splitting member 3 for transmitting fundus illumination light, a field lens 4, a photography strobe light source 5, and a pupil P are conjugated. Ring slit 6,
A lens 7 and a perforated mirror 8 are sequentially arranged. Optical path O2 of the light beam projection optical system for focusing in the incident direction of the light splitting member 3
Above, a visible light diode laser light source 9 that emits light of a wavelength selectively reflected by the light splitting member 3, a cylindrical lens 10, a lens 11 for collimating the light beam of the laser light source 9 in the plane of the paper, as shown in FIG. Slit 12 conjugated to the pupil P
3, a slit plate 12, a lens 13, and, as shown in FIG. 3, an aperture plate 14 conjugated to a standard ocular fundus having three rectangular openings 14a parallel to the slit 12a are sequentially arranged.

The optical path O3 of the observation optical system in front of the eye E
On the upper side, an objective lens 15, a perforated mirror 8, a turret 16 having diopter correction lenses of various powers conjugated to the pupil P, an imaging lens 17, a field lens 18, and a fundus luminous flux from the eye E to be examined are parallel or A collimator lens 19, an imaging lens 20, and an imaging unit 21 for observation and imaging to be substantially parallel.
Are sequentially arranged. Turret 16 for diopter correction
Is provided with a knob 22, and the knob 22 is turned with a finger to rotate the turret 16 so that the diopter correction lens can be replaced.

The output of the imaging means 21 is connected to a memory 23 and a television monitor 24. A general-purpose digital camera 25 is formed by the imaging lens 20, the imaging means 21, the memory 23, and the television monitor 24 in a portion surrounded by a dotted line. It is configured.

In the illumination optical path O1, the light beam from the lamp light source 1 forms an image on a ring slit 6 via a light splitting member 3, a field lens 4, and a strobe light source 5 by a lens 2, and a perforated mirror via a lens 7. The image is re-formed at a pupil conjugate position near 8. In the focusing optical path O2, the light beam from the laser light source 9 is collimated in the plane of the paper by the cylindrical lens 10, and then condensed on the slit plate 12 by the lens 11 in the direction perpendicular to the plane of the paper. The light is reflected by the light dividing member 3 and is projected on the fundus of the eye E through the same optical path as the observation light.

The reflected light from the fundus travels along the observation / photographing optical path O3, forms an image of the pupil P near the perforated mirror 8 by the objective lens 15, passes through the hole of the perforated mirror 8, the turret 16, passes through the imaging lens 17 As a result, an image is formed again near the field lens 18. Further, through the collimator lens 19, an image of the fundus is formed on the imaging means 21 for observation and imaging by the imaging lens 20, the video is displayed on the television monitor 24, and the video signal is stored in the memory 23. Here, the general-purpose digital camera 25 surrounded by a dotted line detects an image blur of the imaging unit 21 by the automatic focusing function, and moves a part of the imaging lens 20 in the optical path O3 direction to perform automatic focusing. .

FIG. 4 shows a sectional view of a light beam at the pupil P. The pupil P has a ring slit image I, a fundus observation light beam O,
The slit light beam F passing through the slit 12a of the slit plate 12 is condensed, and passes through the opening 14a parallel to the slit of the opening plate 14 on the fundus oculi, as shown on the television monitor 24. The light flux H of the book is projected. Since the slit 12a is extremely thin, the light beam H projected on the fundus does not blur in the slit width direction regardless of the diopter of the eye E. If the laser light source 9 has a red wavelength, it is not so dazzling, so that three clear light beams H can be projected on the fundus with light having a high luminance.

At the time of detecting the blur from the image of the image pickup means 21 and performing automatic focusing, the fundus oculi image R may have a signal with little contrast and may not be a bright signal.
Is used to detect blur in the slit width direction, and focus can be easily achieved. Since the focus adjustment range of the digital camera 25 is not very wide, the diopter correction lens is replaced according to the diopter of the eye E, so that the fundus image R is focused. At this time, since the turret 16 is at the pupil conjugate position, the pupil conjugate position projected on the imaging lens 20 does not move even if the power is changed.

Further, the diopter correction lens may be replaced by using a focusing signal from the image pickup means 21. That is, the direction in which the diopter correction lens should be changed is calculated from the movement of the imaging lens 20 and the focusing signal, and the turret 16 is driven by a stepping motor based on the signal to reduce the power of the diopter correction lens. The direction is changed, and the imaging lens 20 is driven again in this state to perform focusing. Thus, the operability can be improved by automating the diopter correction of the eye E.

By using the slit light beam F condensed on the pupil P, a clear focusing target can be projected onto the fundus with a sufficient illuminance regardless of the diopter of the eye E to be examined. It is no longer necessary and the configuration of the focused projection optical system can be simplified. Further, the image pickup means 21 may be sensitive to infrared light, the lamp light source 1 may be an infrared LED light source, and the light source 9 may be an infrared diode laser light source having a wavelength different from that of the laser light source 1. The in-focus state can be easily detected from the blur of the optotype image due to.

The slit light beam F is provided not only in the vertical direction but also in the horizontal direction, and three rectangular optotype images are projected at the same time, and the focus is averaged in two meridian directions using blur in both directions. can do. Also, instead of the slit 12a,
A two-dimensional target may be projected on the fundus with a light beam converged in a point shape on the anterior eye.

FIG. 5 shows a configuration diagram of an optical system of a non-mydriatic retinal camera according to the second embodiment. On the optical path O4 of the fundus photographing illumination optical system, a strobe light source 30, a ring slit 31, a collimator lens 32, a light splitting member 33 that transmits visible light, an imaging lens 34, and a perforated mirror 35 are sequentially arranged. . On the optical path O5 in the incident direction of the light splitting member 33, an infrared LED light source 36 for focusing, an opening plate 37 having an opening serving as a target mark M, a lens 38, and a ring opening conjugate to the pupil P are provided. An aperture plate 39, a light splitting member 40 that transmits light of the wavelength of the infrared LED light source 36, and a collimator lens 41 are sequentially arranged. A lamp light source 42 is provided.

The optical path O6 of the fundus observation photographing system in front of the subject's eye E
On the upper side, an objective lens 43, a perforated mirror 35, a focusing lens 44, an imaging lens 45, a field lens 46, a variable power relay lens 47, an imaging unit having sensitivity to visible light and infrared light are provided from the eye E side. 48 are sequentially arranged, and the aperture plate 37
Is conjugated with the imaging surface of the imaging means 48. The output of the imaging means 48 is connected to a television monitor 49.

In the illumination light path O4, the light beam of the strobe light source 30 is divided into a ring slit 31, a collimator lens 32,
The light passes through the light splitting member 33 and the imaging lens 34, is reflected by the perforated mirror 35, and is projected from the objective lens 43 to the fundus of the eye E to be examined. The luminous flux of the infrared LED light source 36 on the optical path O5 passes through the aperture plate 37, the lens 38, and the aperture plate 3 conjugate with the pupil.
9, the light passes through the light splitting member 40 and the collimator lens 41, is reflected by the light splitting member 33, and is projected on the fundus through the same optical path as the photographing light of the strobe light source 30. The light flux from the incandescent lamp light source 42 is reflected by the light splitting member 40,
The fundus is illuminated through the same optical path as the focused light of the infrared LED light source 36.

The light reflected from the fundus passes through the objective lens 43, the hole of the perforated mirror 35, and the focusing lens 44, and is imaged on or near the field lens 46 by the imaging lens 45. Is re-imaged on the imaging surface of the imaging means 48 via the. The imaging unit 48 captures a fundus image R using infrared light during observation, and captures a fundus image using visible light during imaging. Focusing is performed by a video signal of the imaging means 48, and the video of the television monitor 49 is fetched into the memory as shown in FIG. And drive.

In this focusing optical system, the light splitting member 3
Since 3 is fixed, the number of movable parts is small and the mechanism can be simplified. In addition, since the fundus visual target image M is projected from the ring-shaped light beam in the pupil P, the image is immediately blurred when the focus is out of focus, so that it is possible to automatically focus by applying existing general-purpose technology. When the focusing operation is performed manually, a split prism is used. Alternatively, the aperture plate 37 may be fixed, and the aperture plate 37, the focusing lens 38, and the focusing lens 44 of the photographing system may be interlocked.

[0029]

As described above, the fundus camera according to the present invention projects a focusing target on the fundus, captures a reflected image of the fundus by imaging means, and detects blur of the target image.
Focusing can be performed with high accuracy, and the fundus imaging system can also serve as the focus detection system, so that a simple configuration can be achieved.

Further, the fundus camera according to the present invention reduces the number of movable parts of the focusing light beam projection system by interlocking the focusing operation of the focusing light beam projection system and the focusing operation of the fundus imaging system. And the configuration can be simplified.

In the fundus camera according to the present invention, a target is projected on the fundus by laser light condensed on the anterior segment, and a focusing operation is performed by the reflected image to fix the focusing light beam projection system. Irrespective of the diopter of the eye E, it is possible to focus on the fundus optotype image without blur with high accuracy.

In the fundus camera according to the present invention, the operability of diopter correction can be improved by changing the power of the diopter correcting lens based on the focus detection signal.

In the fundus camera according to the present invention, a pupil conjugate point is provided in the imaging lens system of the image pickup means and focusing is performed by the imaging lens system, so that a change in the pupil conjugate position due to the focusing operation is reduced. The use of a small-diameter imaging lens enables downsizing and simplification.

In the fundus camera according to the present invention, the fundus illumination optical system is provided with a light splitting member for selectively splitting the wavelength light of the focusing light beam by the laser light. The focusing luminous flux can be projected onto the fundus with almost no reduction.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a front view of a pupil conjugate stop.

FIG. 3 is a front view of a fundus conjugate stop.

FIG. 4 is an explanatory diagram of a light beam cross section at a pupil.

FIG. 5 is a configuration diagram of a second embodiment.

[Explanation of symbols]

 1, 42 Lamp light source 3, 33, 40 Light splitting member 5, 30 Strobe light source 6, 31, 39 Ring slit 8, 35 Perforated mirror 9 Laser light source 12 Slit plate 14, 37 Opening plate 16 Turret 21, 48 Imaging means 23 Memory 24, 49 TV monitor 36 Infrared LED light source

Claims (7)

[Claims] 1. A fundus photographing system for photographing a fundus image by an image pickup means, and a focus detection system for projecting a focusing target to the fundus and detecting a fundus reflection image by the image pickup means for focusing. A fundus camera characterized by the following. 2. The fundus camera according to claim 1, wherein a focused light beam is projected on the fundus, and the image pickup means detects a blur and focuses. 3. A fundus camera for dividing a fundus observation illumination optical path and a fundus photographing optical path at a pupil conjugate position of an objective lens,
A fixed light splitting member provided on the fundus observation illumination light path, a focusing light flux projection system for projecting the focusing light flux onto the fundus so as to be able to focus through the light splitting member, and a focusing means for the fundus imaging system Wherein the focusing operation of the focusing light beam projection system and the focusing operation of the fundus imaging system are interlocked. 4. A fundus camera characterized in that a target is projected on the fundus by laser light converging on the anterior eye, and a focusing operation is performed by a fundus reflection image of the target. 5. A fundus camera, wherein the power of a diopter correction lens provided at a conjugate position of an eye to be inspected is changed based on a focus detection signal. 6. A lens for forming a fundus image by an objective lens, and an imaging lens system for forming the fundus image on imaging means, wherein a pupil of an eye to be examined is conjugated to the imaging lens system. And a focusing operation performed by the imaging lens system. 7. A fundus illuminating system for uniformly illuminating a fundus, and a light splitting member for selectively splitting a wavelength light of a focusing light beam by a laser beam is provided in the fundus illuminating system. Fundus camera.