JPH09253052A - Eyegrounds image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the still images of excellent image quality without noise by using a continuously light emitting light source. SOLUTION: Reflected light from the eye ground of an eye E to be tested is received by a photoelectric sensor 13, the signals are read as analog signals by a photoelectric sensor read means 14 and the analog signals are passed through a sample-and-hold circuit 16, then converted to digital signals in an A/D conversion circuit 17 and stored in a storage means 18. Then, the superimposing and averaging processings of plural images are performed in an image processing means 19, output from the image processing means 19 is converted to the analog signals in a D/A conversion means 20, synchronizing signals are added in a synchronizing signal addition circuit 21 and fundus oculi images are displayed on a television monitor 22 as the still images by the television signals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fundus imaging apparatus for taking a fundus image of an eye to be examined.

[0002]

2. Description of the Related Art In a conventional fundus imaging device, a fundus image is generally displayed as a moving image by a scanning laser optical system.
The signal for the screen is frozen to obtain a still image. Also,
2. Description of the Related Art In a fundus imaging apparatus that illuminates a fundus with a lamp and obtains a fundus image with a television camera, a flash light source such as a strobe is used in order to obtain a still image with good image quality.

[0003]

However, in the above-mentioned conventional example, when a moving image is frozen to be a still image, noise is noticeable, which is not preferable. Further, in fluorescence photography using a flash light source, after intravenous injection of a fluorescent agent. Different images are obtained in the initial state of a bright image with abrupt changes in the image, in the medium state with a gradual change, and in the late state of an image with very little change, but more images are needed depending on the purpose of diagnosis. As a result, fluorescence imaging takes a long time, which imposes a burden on the subject.

The object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a fundus imaging device that obtains a still image of good image quality without noise by using a continuous light emitting light source.

[0005]

In order to achieve the above object, a fundus imaging apparatus according to the present invention includes a fundus illuminating means for illuminating the fundus and a photoelectric sensor for receiving a luminous flux from the fundus by the fundus illuminating means. In a fundus imaging device for obtaining a fundus image,
Storage means for storing the fundus image from the photoelectric sensor as a digital signal, superposition calculation means for superposing the positions of the fundus images stored in the storage means, and the fundus image superposed by the calculation means as a still image. Display means for displaying.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 is a block diagram of a fundus imaging apparatus using laser scanning according to the first embodiment. On a light path from a laser light source 1 to an objective lens 2, a condenser lens 3 and a small aperture conjugate with a fundus of an eye E to be examined. Aperture 4, focus lens 5,
A diaphragm 6 that determines the luminous flux on the pupil of the eye E to be inspected, a perforated mirror 7, a horizontal scanning mirror 8 including a resonance mirror conjugate to the pupil of the eye E to be examined, a lens 9, a galvano mirror conjugate to the pupil of the eye E to be examined, and the like. The vertical scanning mirrors 10 are sequentially arranged. On the optical path in the reflection direction of the perforated mirror 7, a focus lens 11 and a confocal diaphragm 1 conjugate with the fundus of the eye.
2, the photoelectric sensor 13 is arranged, the focus lens 5,
Reference numeral 11 is adapted to move in conjunction with the diaphragm 4 while maintaining a conjugate relationship.

The output of the photoelectric sensor 13 is connected to the photoelectric sensor reading means 14, one of the outputs of the photoelectric sensor reading means 14 is directly connected to the control means 15, and the other is connected to the sample hold circuit 16 and A / D conversion. It is connected to the control means 15 via a circuit 17. The output of the A / D conversion circuit 17 is a storage unit 18 including a frame memory and the like, and an image processing unit 1 for superposing and averaging a plurality of images.
9, the D / A conversion circuit 20, the synchronization signal addition circuit 21, and the television monitor 22 are sequentially connected, and these storage means 18, image processing means 19, D / A conversion circuit 20, and synchronization signal addition circuit 21 are connected. The output of the control means 15 is connected to each.

FIG. 2 is a block circuit diagram of the image processing means 19, which comprises three switches 23, 24 and 25, an image superposition arithmetic circuit 26, an image averaging arithmetic circuit 27 and a memory 28. The output from the storage means 18 is connected to the switch 23, and one terminal 23a of the switch 23 is connected to the image superposition arithmetic circuit 26 and the other terminal 2
3b is connected to the terminal 25b of the switch 25. The output of the image superposition arithmetic circuit 26 is connected to the image averaging arithmetic circuit 27 and the terminal 24b of the switch 24, and the output of the image averaging arithmetic circuit 27 is the other terminal 24 of the switch 24.
a. The output from the switch 24 is connected to the memory 28, the output of the memory 28 is connected to the terminal 25a of the switch 25, and the switch 25 is D
It is connected to the / A conversion circuit 20. Also, the control circuit 1
The output of 5 is the switches 23, 24 and 25, the image superposition arithmetic circuit 26, the image averaging arithmetic circuit 27, and the memory 28.
Connected to each.

In the above structure, the light beam from the laser light source 1 is condensed by the condenser lens 3 on the small aperture stop 4, and the focus lens 5, the perforated mirror 7, the horizontal scanning mirror 8, the lens 9 and the vertical scanning mirror 10 are formed. Then, the fundus of the eye E is scanned and illuminated at a television rate through the objective lens 2. The reflected light or excited fluorescence returns through the same optical path, is reflected by the perforated mirror 8, passes through the focus lens 11, and is received by the photoelectric sensor 13 through the confocal diaphragm 12.

The signal from the photoelectric sensor 13 is read out as an analog signal by the photoelectric sensor reading means 14, and this analog signal passes through the sample hold circuit 16 and then is transferred to A
The digital signal is converted by the / D conversion circuit 17 and stored in the storage unit 18. Then, the image processing means 19 superimposes and averages a plurality of images, and the output from the image processing means 19 is converted into an analog signal by the D / A conversion means 20 and then synchronized by the synchronization signal addition circuit 21. The signals are added and converted into a normal television signal such as NTSC or PAL, and the eye fundus image is displayed on the television monitor 22 by this television signal.

Since the change is fast in the initial stage of the fluorescent photographing, it is desirable to observe the moving image. When the photographer selects the moving image mode with the operation switch (not shown), the control means 15 causes the switches 23, 24 and 25 of the image processing means 19 to be switched. Is connected to the terminals 23b, 24b, 25b by switching to the moving image observation state. As a result, the output from the storage means 18 is
The image superposition calculation means 19 does not perform the superposition processing, but the output is directly output from the switch 23 to the D / A conversion means 20, and the sync signal is added by the sync signal addition circuit 21 to be converted into a normal television signal. A moving image is displayed on the television monitor 22, and the photographer observes it.

Next, in the latter stage of the fluorescence photographing, since there is almost no change and the fluorescence image is in a very dark state, the photographer selects the superposition mode by the operation switch (not shown). Here, the control means 15 switches the switches 23, 24, 25 of the image processing means 19 to the superimposing image observation state, that is, the terminals 23a, 24a, 25a. As a result, the output from the storage means 18 is stored in the memory 28 without the averaging process, although the image superposition arithmetic circuit 26 performs the superimposing process, and then D /
The still image displayed on the television monitor 22 can be observed by outputting to the A conversion means 20 and adding the synchronizing signal in the synchronizing signal adding circuit 21.

In the image superposition arithmetic circuit 26, the positions of a plurality of consecutive screens are aligned and superposed to produce one still image. That is, one pixel is shifted by one pixel and subtraction is performed for each pixel. When the positions are matched, the difference is minimized, so that the positions are overlapped. When about 10 screens are overlapped, the signal component of the image portion is increased 10 times, but the random noise mainly generated in the photoelectric sensor 13 is averaged and becomes inconspicuous, and the image quality is improved. This corresponds to the sensitivity of the photoelectric sensor 13 being increased 10 times. At the TV rate, it is a fraction of a second with 10 screens, so the memory 2
Rewriting the value of 8 makes it possible to observe even a moving image, and it is particularly preferable because it can sufficiently follow a fluorescent fundus image from the middle period onwards, where the change is relatively slow.

Further, in the case of an image having a poor S / N, a highlight portion is present in a part of the image, and the highlight portion is saturated in a simple superimposing process. Selects the averaging mode. The control means 15 is a switch 23 of the image processing means 19,
24 and 25 are in an averaged image observation state, that is, terminals 23a and 2
Switch to 4a, 25a. As a result, the output from the storage means 18 is input to the image averaging processing circuit 27 after being subjected to the superimposing processing in the image superimposing arithmetic circuit 26, and is averaged by dividing by the number of superposed images. Is processed and stored in the memory 28, and then D
It is output to the / A conversion means 20. Then, similarly, the synchronization signals are added by the synchronization signal adding circuit 21, a still image is displayed on the television monitor 22, and an image with a good S / N in which only random noise components are suppressed by averaging can be observed. it can.

FIG. 3 is a block diagram of the second embodiment, and FIG.
Functional elements that are the same as are denoted by the same numbers. Photoelectric sensor 1
The output of 3 is connected to the video signal circuit 30, and the output of the video signal circuit 30 corresponds to the processing contents of the storage means 31 and the image processing means 19 provided with digital video whose input and output are analog and the storage part uses a digital signal. It is connected to one side of the analog switch 33 via the image processing means 32 for performing analog, and the video signal circuit 30 is connected to the other side of the analog switch 33.
Are directly connected. The output of the video signal circuit 30 is connected to the control means 15, and the output of the control means 15 is the storage means 31, the image processing means 32, and the analog switch 33.
, And the output from the analog switch 33 is connected to the television monitor 22.

The signal from the light receiving sensor 13 is read by the video signal circuit 30, and at the same time converted into a video signal and output. This signal is stored in the storage means 31 as a digital signal, analog-processed in the image processing means 32, and thereafter, by operating the analog switch 33, the video signal circuit 30 and the image processing means 3 based on the control signal of the control means 15.
The output of 2 is selected and output to the television monitor 22.

Also in the case of the present embodiment, since the fundus image is stored as a digital signal, the image quality does not deteriorate even during the arithmetic processing.

In the above description, the embodiment in which the laser scanning optical system is used as the fundus imaging device is shown, but the invention can also be applied to the fundus imaging device using the television imaging optical system, the storage means and the signal processing. The means can be used as it is as in this embodiment.

[0019]

As described above, the fundus imaging apparatus according to the present invention stores the fundus image from the photoelectric sensor as a digital signal, aligns the positions of the fundus images, and superimposes them on the display means. By displaying the image as an image, a fundus still image with good image quality can be obtained by using, for example, a continuously lit light source, and a still fundus image can be taken with weak light by increasing the sensitivity of the light receiving optical system.

[Brief description of drawings]

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

FIG. 2 is a block circuit configuration diagram of an image processing unit.

FIG. 3 is a configuration diagram of a second embodiment.

[Explanation of symbols]

 1 Laser Light Source 7 Perforated Mirror 8 Horizontal Scanning Mirror 10 Vertical Scanning Mirror 13 Photoelectric Sensor 14 Readout Means 15 Control Means 16 Sample Hold Circuit 18, 28, 31 Storage Means 19, 32 Image Processing Means 21 Sync Signal Adder Circuit 22 Television Monitor 30 Video signal circuit

Claims (3)

[Claims] 1. A fundus illuminating means for illuminating a fundus and a fundus imaging apparatus for receiving a luminous flux from the fundus by the fundus illuminating means to a photoelectric sensor to obtain a fundus image, wherein the fundus image from the photoelectric sensor is converted into a digital signal. A storage unit for storing the same, a superposition calculation unit for superposing the positions of the fundus images stored in the storage unit, and a display unit for displaying the fundus images superposed by the calculation unit as a still image. Fundus imaging device. 2. A calculation result of the superposition calculation means,
The fundus imaging apparatus according to claim 1, further comprising averaging calculation means for averaging by dividing by the number of superimposed images. 3. The fundus imaging apparatus according to claim 1, further comprising switching means for switching between moving image output and still image output.