JPH10234673A - Eyebottom camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily perform focusing by displaying a moving amount caused by a moving means for moving the focusing lens and target plate of the observation optical system while interlocking them. SOLUTION: The light flux in infrared area passed through a photographic iris 22 is reflected through a focusing lens 23 and an image forming lens 25 onto a dichroic mirror 26 and an image is formed on the imaging device of a CCD camera 30 for observation by a relay lens 28 later. The eyebottom observed image provided by the CCD camera 30 for observation is displayed on a monitor for observation. In this case, concerning erected image moving at a point A, the focusing lens 23 corrects the refracting power of eye to be examined, and moved for focusing the CCD camera 30 for observation and at the same time, a chart panel 16 is interlocked. Then, the moving amount of the focusing lens 23 is replaced with the refracting power of eye to be examined, and displayed outside by a refracting power display meter 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus camera for photographing a fundus of a subject's eye, and more particularly, to a focus mechanism suitable for focusing a fundus image illuminated with infrared light.

[0002]

2. Description of the Related Art In a conventional fundus camera for photographing the fundus of an eye to be examined, infrared light is used as illumination light for observation, so that a fundus image can be formed without using a special chemical such as a mydriatic agent. There is known a non-mydriatic pupil system capable of taking a picture. However, the fundus image illuminated with the observation light beam of infrared light is
Since the image is mainly a red blood vessel image, the contrast is low as a whole, and the image is unclear. It was very difficult to focus only on this fundus image.

In view of this, an index projection optical system for projecting an in-focus target on the fundus is provided, and the index image projected onto the fundus by using an oblique mirror to be coaxial with the optical axis of an observation illumination optical system. An apparatus has been proposed which determines whether the focus of the fundus oculi image is appropriate by observing the state of the eye.

[0004]

SUMMARY OF THE INVENTION
When the scum range is enlarged, there is a drawback that the user has no idea which direction to move for focusing, and the operation may take time.

The present invention has been made in view of the above-mentioned prior art, and has as its technical object to provide a fundus camera capable of performing focusing more easily.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is characterized by having the following configuration.

(1) In a fundus camera having a photographing optical system for photographing the fundus of the eye to be examined, a first illumination optical system for illuminating the fundus of the eye with infrared light, and one of the first illumination optical system and an optical path. A second illumination optical system that illuminates the fundus of the subject's eye with visible light for imaging, a target projection optical system that projects a target for focusing on the fundus of the subject's eye, a focusing lens and an infrared light source. An observation optical system that has an imaging element having sensitivity and observes the fundus of the eye to be inspected illuminated by the infrared light of the first illumination optical system and an index image of the index plate projected on the fundus; and an observation optical system. Image display means for displaying the obtained image, moving means for moving the focusing lens and the index plate of the observation optical system in conjunction with each other, and movement amount display means for displaying the movement amount by the movement means. Characterized by You.

(2) In the fundus camera according to (1), the movement amount display means converts the movement amount into refractive power and displays the converted amount.

(3) In the fundus camera according to (1), the range in which the focusing lens is moved by the moving means to cover the focus is from the close-up photographing of the anterior segment to the fundus photographing.

(4) In the fundus camera according to (1), the index plate is a focus index plate arranged in an optical path shared by the first and second illumination optical systems, and the index portion covers a visible region. The filter is characterized by being formed of a filter having a wavelength characteristic of transmitting and blocking infrared light.

(5) In the fundus camera according to (1), the photographing optical system shares a part of the optical path with the observation optical system.
The photographing optical system and the observation optical system are characterized in that the optical path is branched by a wavelength selective transmission mirror for selecting the wavelength between infrared light and visible light.

(6) The fundus camera of (1) has a hand-held housing.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a fundus camera according to an embodiment. The fundus camera according to the embodiment includes a photographing unit 1 in which an optical system for observation and photographing is housed in a housing suitable for hand-held operation, a control unit 2 for controlling the photographing unit 1, an observation monitor 3, and a display monitor. 4, a filing device 5, and a video printer 6, each of which is electrically connected.

FIG. 2 is a diagram showing an optical system of the fundus camera. The optical system will be described separately for an illumination / index projection optical system and an observation / photographing optical system.

(Illumination / index projection optical system) 11 is an infrared light emitting diode which is an illumination light source for observation, and the infrared light emitting diode 11 also serves as an index projection light source for focusing. Reference numeral 12 denotes a diffusion plate, and 13 denotes a condenser lens. 1
A flash light source 4 is a light source for photographing and emits a visible light beam. Reference numeral 15 denotes a ring slit which is a ring-shaped aperture stop, and reference numeral 16 denotes a chart plate for projecting an index onto the fundus of the eye to be examined for focusing on a region to be imaged. As shown in FIG. 3, the chart plate 16 has an index mark 16a partially composed of crosshairs. The index mark 16a is made of a coating (optical thin film) having a wavelength characteristic of transmitting visible light and blocking infrared light. The use of the cross-shaped index is convenient because it is easy to confirm the part to be focused from the center to the periphery at the position on the line, but the shape is not limited to this. Another portion 16b around the index mark 16a is a transmission region that transmits both visible and infrared light. The chart plate 16 moves in the direction of the optical axis (in the direction of the arrow) in synchronization with a focusing lens 23 of an observation / photographing optical system described later, and is placed at a conjugate position while focusing on the fundus.

Reference numeral 17 denotes a light projecting lens, and reference numeral 18 denotes a beam splitter for coaxially setting an optical axis of an illumination / index projection optical system and an optical axis of an observation / photographing optical system described later. Reference numeral 19 denotes a black absorber, which absorbs illumination light that has been attenuated and transmitted through the beam splitter 18 so as to prevent unnecessary noise light from entering the observation / photographing optical system. E indicates the eye to be examined.

The infrared light emitted from the infrared light emitting diode 11 is made uniform by the diffusion plate 12 and then converged by the condenser lens 13 to illuminate the entire ring slit 15. The illumination light limited in a ring shape by the ring slit 15 further illuminates the chart plate 16. Transmission area 1
The light beam transmitted through 6b is incident on the beam splitter 18 via the light projecting lens 17, the amount of light of which is attenuated and reflected by about ２, and travels toward the eye E. When the imaging unit 1 is located at a predetermined working distance, the light flux restricted in a ring shape by the ring slit 15 becomes conjugate with the vicinity of the pupil of the subject's eye E, and once diffuses after forming a ring slit image,
The fundus of the same or slightly wider field of view is illuminated with infrared invisible light. At this time, since the index mark 16a on the chart plate 16, the light projecting lens 17 and the lens of the eye E constitute an imaging optical system with respect to the fundus, the index mark is formed of infrared light. It is projected on the fundus as a shaded part.

The light emitted from the flash light source 14 illuminates the ring slit 15 and the chart plate 16.
At this time, since the index mark 16a passes through the visible range, the visible light beam for photographing passes without being restricted by the chart plate 16. The light beam that has passed through the chart plate 16 illuminates the fundus of the subject's eye via the same optical path as the illumination light beam from the infrared light emitting diode 11.

(Observation and photographing optical system) 21 is an observation objective lens, and 22 is a photographing diaphragm arranged at a position conjugate with the vicinity of the pupil of the eye E to be examined, similarly to the ring slit 15. Reference numeral 23 denotes a focusing lens, which can be moved in the optical axis direction (the direction of the arrow) by a lens moving mechanism (not shown) in order to perform adjustment in accordance with the refractive power of the eye to be inspected. Focusing by the focusing lens 23 is possible from fundus photography centering on 0D (for example, +10 to -10D) to close-up photography (for example, +35 to -10D) of the anterior ocular segment. Reference numeral 24 denotes a refractive power display meter that displays the amount of movement of the focusing lens 23 by replacing it with the refractive power of the eye to be examined. 25 is an imaging lens, 26 is a dichroic mirror, the dichroic mirror 26 reflects infrared light,
It has the property of transmitting visible light. 27 is CC for shooting
D camera.

Reference numeral 28 denotes a relay lens for extending the optical path, 29 denotes a mirror for returning mirror image reversal, and 30 denotes a CCD camera for observation.

The fundus of the eye to be examined is illuminated by infrared illumination light from an illumination / index projection optical system. The reflected light from the fundus due to this illumination exits the center of the optical axis that does not overlap the ring image formed by the ring slit 15 near the pupil. The light beam emitted from the eye E is further attenuated by about 約 by the beam splitter 18, forms an inverted image once at the point A by the objective lens 21, and then passes through the photographing diaphragm 22. Since the photographing aperture 22 is substantially conjugate with the pupil, the diameter of the photographing light beam taken out of the pupil of the eye E is determined by the photographing aperture 22 so as not to overlap with the peripheral ring image formed by the ring slit 15. The inverted image at the point A changes its position on the optical axis due to the refractive power (diopter) of the eye E.

The light beam in the infrared region that has passed through the photographing aperture 22 is
After passing through the focusing lens 23 and the imaging lens 25 and reflected by the dichroic mirror 26, the relay lens 2
8 forms an image on the image sensor of the observation CCD camera 30. The fundus image picked up by the observation CCD camera 30 is displayed on the observation monitor 3. Here, in response to the movement of the inverted image at the point A, the focusing lens 23 corrects the refractive power of the eye to be inspected, and is moved for the purpose of focusing on the observation CCD camera 30. It is configured so that it can be accurately projected on the fundus. The difference in the amount of movement between the focusing lens 23 and the chart plate 16 in conjunction with each other can be corrected by connecting the focusing lens 23 and the chart plate 16 via a cam or the like.

The amount of movement of the focusing lens 23, which moves for the purpose of correcting the refractive power of the eye to be examined and focusing on the observation CCD camera 30, can be replaced by the refractive power of the eye to be examined. This is replaced and displayed externally by the refractive power display meter 24 (it is convenient but not essential to replace the moving amount with the refractive power). As another method, since the chart plate 16 also moves in conjunction with the focusing lens 23, the moving amount of the chart plate 16 is replaced with the refractive power of the eye to be examined, and the refractive power display meter 2 is used.
4 can also be displayed externally. Further, the refractive power display detects the amount of movement of the focusing lens 23 or the chart plate 16 by a method such as electrical, magnetic or optical, and obtains the refractive power from the amount of movement by a computer, thereby obtaining an observation monitor 3 or the like. Can also be displayed.

The visible reflected light beam from the fundus illuminated by the photographing flash light source 14 is reflected by the objective lens 21 and the photographing diaphragm 2 in the same manner as the fundus reflected light beam by infrared light.
2. The light enters the dichroic mirror 26 via the focusing lens 23 and the imaging lens 25. Since the dichroic mirror 26 transmits a visible light beam, the visible fundus reflected light beam forms an eye fundus image on the imaging element surface of the imaging CCD camera 27 by the imaging lens 25. At this time, since the chart plate 16 transmits visible light, which is a photographing light beam, on the entire surface, the index image of the chart plate 16 is not formed in the visible region. Further, since the infrared light beam is reflected by the dichroic mirror 26, it does not enter the imaging CCD camera 27. Therefore, the imaging CCD camera 2
7 can obtain a fundus image which is not affected by the chart plate 16. The fundus image obtained by the imaging CCD camera 27 is displayed on the display monitor 4 as a still image.

The operation of the fundus camera having the above configuration will be described below with reference to a block diagram of a main control system shown in FIG. As the imaging environment, it is preferable that the brightness of the subject is slightly dimmed, and that the pupil of the subject's eye is wide open in a natural mydriatic state. The drive circuit is operated by a switch (not shown) provided in the control unit 2 to turn on the infrared light emitting diode 11. The photographer holds the housing of the imaging unit 1 with his / her hand, and approaches the imaging unit 1 from slightly before the eye E to illuminate the eye E. Since the observation illumination light beam and the target projection light beam are invisible infrared light beams, the eye E can be illuminated without any burden.

The reflected light beam from the subject's eye illuminated by the infrared light beam is captured by the observation CCD camera 30, and the captured image is passed through the camera control circuit 31 to the observation monitor 3.
It is projected on. Since the image of the subject's eye observed on the observation monitor 3 starts to be illuminated slightly before, the image of the anterior segment of the subject's eye is first displayed. When the photographer approaches the apparatus to near the working distance position of the fundus camera while observing the image, the pupil image expands on the observation monitor 3 and the fundus image comes to be projected.

FIG. 5 shows an example of an image displayed on the observation monitor 3 at this time. In this state, the index image 51 formed as a black shadow by the index mark 16a of the chart plate 16 is projected on the observation monitor 3 at the same time as the fundus image, and can be confirmed. The photographer stops moving the photographing unit 1 when the pupil image of the subject's eye becomes a desired size (when the working distance is matched).

When the fundus image is projected on the observation monitor 3, if the focusing lens 23 is moved in advance in accordance with the refractive power of the eye to be inspected by the refractive power display meter 24, the focusing is performed while watching the screen that is out of focus at all. Focusing can be performed more efficiently than moving the lens 23 to focus the fundus. In this case, it is necessary to know the refractive power of the subject's eye in advance, but in ophthalmological treatment, the refractive power of the eye is generally measured using an objective eye refractive power measurement device or the like at the initial examination stage. Therefore, the measurement result may be used. Even when the refractive power of the eye to be examined is not known in advance, if the focusing lens 23 is returned so that the refractive power display meter 24 is set to 0D, it is possible to obtain a substantially close focus on the fundus of many subjects. is there.

When an approximately focused fundus image is displayed on the observation monitor 3 in this manner, the focusing lens 23 is further moved to more accurately focus the fundus. Since the fundus image illuminated by infrared light is mainly composed of red blood vessel images, the contrast is low as a whole. Focusing by an unskilled person is not easy with this observation alone, but the target image is displayed on the monitor 3. Since the image 51 is displayed, it is observed and focused.
Since the index image 51 is displayed as a black shadow with a clear contrast as compared with the fundus image which is displayed whitish on the black and white screen of the monitor 3, the photographer focuses on the index image 51 so that the index image 51 becomes clearest. The chart plate 16 also moves in conjunction with the movement of the focusing lens 23. When focus is achieved, the focusing lens 23 is placed on the fundus (ie, an inverted image at point A) with the imaging CCD camera 27,
The imaging planes of the observation CCD camera 30 are set to conjugate positions.

Further, the amount of movement of the focusing lens 23 at the time of focusing is displayed on the refractive power display meter 24 as the refractive power of the eye to be inspected, so that it is also a guide for confirming the refractive power of the eye to be inspected.

Next, while observing the screen of the observation monitor 3, the photographer moves the desired fundus photographing region around the pupil by shaking the photographing unit 1 to determine the desired position finely. In addition,
It is also possible to use a well-known method of determining the imaging region by moving the line of sight of the subject's eye with an external fixation lamp.

When the determination of the fundus photographing region is completed, the photographing switch 32 provided on the photographing unit 1 is pressed. When the photographing switch 32 is pressed, a trigger signal is generated, and the signal is input to the timing circuit 33 of the control unit 2. The timing circuit 33 includes a synchronization signal separation circuit 34
The operation signal is sent to the flash light source drive circuit 35 and the memory control circuit 36 in synchronization with the synchronization signal from the photographing CCD camera 27 input through the camera. The fundus image illuminated by the emission of the flash light source 14 is a photographing CCD.
It is captured by the camera 27. A video signal captured by the imaging CCD camera 27 is digitized by an A / D converter 37 and stored in a frame memory 38 in synchronization with a signal from a memory control circuit 36.

The photographed image stored in the frame memory 38 is converted into an analog signal by a D / A converter 39,
The video signal is sent to the display monitor 4 via the video amplifier circuit 40 and instantly displayed. Since the fundus image projected on the display monitor 4 is in the visible region of which the wavelength is selected by the dichroic mirror 26 with the steady light from the flash light source 14, the index mark 16a only restricts the infrared region.
Image is not projected.

The photographer checks whether the fundus image projected on the display monitor 4 has been photographed well. If the photographed image is not good, the photographer resets the photographing conditions such as adjusting the light amount of the flash light source 14, and the like. Perform shooting again with the same operation.

When storing a captured image, the filing device 5 is operated to store data. Filing device 5
The image data of the fundus image stored and stored in the image data can be freely reproduced, and unnecessary image data is deleted and edited. Also, if you need a print image for pasting on medical records, etc.,
The printout is performed by operating the video printer 6.

Further, when observing and photographing not only the fundus but also the anterior segment, a strong positive refractive power is required to bring the focus into close proximity. By moving the focusing lens 23 in the direction of the positive refractive power, focusing can be performed efficiently.

Although the observation monitor 3 is provided separately from the photographing unit 1 as in the embodiment, a small liquid crystal display or the like is employed in place of the observation monitor 3, and this is used for the photographing unit 1. Operability is further improved by arranging them. The observation monitor 3 and the display monitor 4
Alternatively, the observation image and the photographed image may be viewed on one monitor by providing an image switching unit. As described above, this embodiment can be variously modified without changing the technical idea, in addition to the above-described modified examples.

[0038]

As described above, according to the present invention,
By providing a mechanism that displays the amount of movement of the lens to be moved for focusing as the refractive power of the subject's eye, it is possible for the photographer to eliminate the hesitation of seeing a screen that is largely out of focus, The alignment operation can be performed efficiently, and it can be used particularly as an unstable hand-held device. In addition, a structure that can easily display an index for focusing at the time of observation and remove an index at the time of imaging can simplify and reduce the weight of the apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a fundus camera according to an embodiment.

FIG. 2 is a configuration diagram of a main part of an optical system of a fundus camera according to an embodiment.

FIG. 3 is a diagram showing a chart plate as an example.

FIG. 4 is a main part control system block diagram of the fundus camera according to the embodiment.

FIG. 5 is a diagram showing an example of a fundus oculi image displayed on an observation monitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Imaging unit part 3 Observation monitor 11 Infrared light emitting diode 14 Flash light source 15 Ring slit 16 Chart board 16a Index mark 18 Beam splitter 23 Focusing lens 24 Refractive power meter 27 CCD camera for photographing 30 CCD camera for observation

Claims (6)

[Claims] 1. A fundus camera having a photographing optical system for photographing a fundus of an eye to be examined, a first illumination optical system for illuminating the fundus of the eye with infrared light, and a part of the first illumination optical system and a part of an optical path. A second illumination optical system for illuminating the fundus of the subject's eye with visible light for photography, an index projecting optical system for projecting an index for focusing on the fundus of the eye to be inspected, and a focusing lens and sensitivity in the infrared region Observation optical system having an imaging device having the following. Observation optical system for observing the fundus of the eye to be inspected illuminated by the infrared light of the first illumination optical system and the index image of the index plate projected on the fundus; Image display means for displaying the projected image, moving means for moving the focusing lens and the index plate of the observation optical system in conjunction with each other, and movement amount display means for displaying the movement amount by the movement means. Featured fundus camera. 2. The fundus camera according to claim 1, wherein said moving amount display means converts the moving amount into refractive power and displays the converted amount. 3. A fundus camera according to claim 1, wherein a range in which the focusing lens can be moved by the moving means covers a range from close-up photography to fundus photography of an anterior eye or the like. . 4. The fundus camera according to claim 1, wherein the index plate is an index plate for focusing disposed in an optical path shared by the first and second illumination optical systems, and the index portion transmits a visible region. A fundus camera characterized in that the fundus camera is formed of a filter having a wavelength characteristic that blocks infrared light. 5. The fundus camera according to claim 1, wherein the photographing optical system shares a part of an optical path with the observation optical system, and the photographing optical system and the observation optical system select wavelengths of infrared light and visible light. A fundus camera, wherein an optical path is branched by a wavelength selective transmission mirror. 6. The fundus camera according to claim 1, wherein the fundus camera has a hand-held housing.