JP7094268B2 - Fundus photography device - Google Patents

Description

The present invention relates to a fundus photography apparatus.

In the fundus photography with visible light, in order to prevent the pupil from closing due to the visible light shining on the fundus, invisible light such as infrared light that the eye does not detect is used to pre-adjust the eye to be inspected and the optical system (optical axis alignment). , Focusing, etc.) (see, for example, Patent Document 1).

Japanese Patent No. 5087701 Japanese Patent No. 5215675 International Publication No. 2016/136859

In the fundus photography device, the position of the focus lens is adjusted prior to the fundus photography. However, since there is chromatic aberration between visible light and invisible light, when the position adjustment of the focus lens is performed using invisible light, it is necessary to consider the positional deviation of the focus lens due to the chromatic aberration. However, adjusting the position of the focus lens according to the chromatic aberration complicates the control of the operation mechanism of the focus lens.

Therefore, the present application discloses a fundus photography apparatus that can realize the position adjustment of the focus lens using invisible light, which is performed prior to the fundus photography with visible light, without requiring complicated control.

In order to solve the above problems, in the present invention, an image sensor having at least sensitivity to visible light and invisible light is used, and when photographing the fundus using visible light, the focus lens is aligned with the position where the invisible light is focused. I decided to do it in a state of being. Then, the optical path difference between the visible light and the invisible light is corrected by inserting and removing the optical path correction member.

Specifically, the present invention is a fundus imaging device, an image pickup element having sensitivity to at least visible light and invisible light, a focus lens arranged in the middle of an optical path from the subject's eye fundus to the image pickup element, and a subject's eye. The focus optotype is projected with a second invisible light having a peak wavelength different from that of the first invisible light used for observing the fundus of the eye, and the focus lens is aligned with the position where the image of the focus optotype obtained by the image pickup element is in focus. It includes a focus adjusting means and an optical path correction member that is inserted and removed when the subject's eye fundus is photographed with visible light and corrects the optical path difference between the visible light and the invisible light from the subject's eye fundus to the image pickup element.

Here, the invisible light is light that is not perceived by the human eye, and for example, infrared light can be applied. Further, the first invisible light is invisible light having a predetermined wavelength as a peak, and for example, infrared light having a wavelength of 850 nm as a peak can be applied. Further, the second invisible light is invisible light having a peak wavelength different from a predetermined wavelength, and for example, infrared light having a peak wavelength of 805 nm can be applied.

The focus adjusting means of the fundus photography device described above aligns the focus lens at a position where the image of the focus target projected by the second invisible light is in focus. Then, the image of the fundus using visible light is performed with the focus lens aligned with the position where the focus lens is focused by invisible light. That is, in the operation mechanism of the focus lens, complicated control in consideration of the chromatic aberration between visible light and invisible light is not performed. Then, the in-focus position due to the chromatic aberration between the visible light and the invisible light is adjusted by the optical path correction member inserted and removed during the fundus photography using the visible light. Since this adjustment is realized by a simple operation of inserting and removing the optical path correction member, it does not require complicated control required for the position adjustment of the focus lens in consideration of chromatic aberration.

The focus adjusting means may be one that aligns the focus lens with a position where the image of the focus optotype obtained by the image pickup device is in focus when the first invisible light is turned off. If the fundus photography device described above is provided with such a focus adjusting means, the focus optotype can be clearly captured.

Further, in the above focus adjusting means, an image of a focus optotype obtained by an image sensor when the first invisible light is turned off during fundus observation performed by blinking the first invisible light every frame is obtained. The focus lens may be aligned with the in-focus position. If the above-mentioned fundus photography device is provided with such a focus adjusting means, the focus adjustment is performed during the fundus observation.

Further, the optical path correction member may have a function of blocking invisible light. If the fundus photography device is provided with such an optical path correction member, invisible light is not reflected in the photographed image of the fundus, so that a clear photographed image of the fundus can be obtained.

Further, the fundus photography apparatus may include a plurality of optical path correction members corresponding to each of the plurality of types of lenses exchanged according to the magnification. If the fundus imaging device is provided with such an optical path correction member, a clearer photographed image of the fundus can be obtained.

With the above-mentioned fundus photography device, it is possible to realize the position adjustment of the focus lens using invisible light, which is performed prior to the fundus photography with visible light, without requiring complicated control.

FIG. 1 is a diagram showing a schematic configuration of an optical system of the fundus photography apparatus of the present embodiment. FIG. 2 is a block diagram of an electric circuit provided in the fundus photography device. FIG. 3 is a diagram showing a processing flow realized by the fundus photography apparatus. FIG. 4 is a diagram showing a timing chart of each process realized when a wide-angle lens is selected. FIG. 5 is a diagram showing an example of an image acquired by the image sensor. FIG. 6 is a diagram showing an example of an image displayed on the LCD panel. FIG. 7 is a diagram showing an example of an image in which fundus images used for detection processing of a focus optotype are arranged. FIG. 8 is a first diagram showing a method of determining focus. FIG. 9 is a second diagram showing a method of determining focus. FIG. 10 is a third diagram showing a method for determining focus. FIG. 11 is a first diagram comparing the in-focus positions. FIG. 12 is a diagram showing a timing chart of each process realized when the narrow angle lens is selected. FIG. 13 is a second diagram comparing the in-focus positions.

Hereinafter, embodiments of the present invention will be described. The embodiments shown below are examples of embodiments of the present invention, and the technical scope of the present invention is not limited to the following embodiments.

FIG. 1 is a diagram showing a schematic configuration of an optical system of the fundus photography apparatus of the present embodiment. The fundus imaging device 1 is a device that photographs the fundus of the eye to be inspected E, and includes an objective lens 2, a perforated mirror 3, a focus lens 4, a half mirror 5, an internal fixation lamp 6, a relay lens 7, and a focus dot mirror 8. Focus optotype projection system 9, black dot glass 10, relay lens 11, ring slit 12, diffuser 13, shooting illumination 14, observation illumination 15, imaging lens 16, narrow angle lens 17, wide angle lens 18, optical path It includes a correction glass 19 (an example of the “optical path correction member” in the present application) and an image sensor 20.

First, the positional relationship and functions of each component included in the fundus photography apparatus 1 will be described. The objective lens 2 is a lens located in front of the eye E to be inspected. A perforated mirror 3, a focus lens 4, a half mirror 5, and an internal fixation lamp 6 are arranged in this order on the optical axis behind the objective lens 2. The perforated mirror 3 is a mirror in which a through hole is formed in a portion through which the optical axis of the objective lens 2 passes, and is fixed in the fundus photography device 1 at an appropriate tilt angle with respect to the optical axis of the objective lens 2. ..

On the axis of the illumination optical system that guides the illumination light reflected by the effective mirror and irradiates the eye E to be inspected, the relay lens 7, the focus dot mirror 8, the black dot glass 10, and the relay lens 11 are arranged in order from the perforated mirror 3 side. A ring slit 12, a diffuser plate 13, a shooting light 14, and an observation light 15 are arranged. Therefore, the light emitted from the photographing illumination 14 and the observation illumination 15 becomes annular irradiation light in the process of passing through the diffuser plate 13 and the ring slit 12, and becomes a relay lens 11, a black dot glass 10, a focus dot mirror 8, and a relay. It is reflected by the perforated mirror 3 through the lens 7 and illuminates the fundus of the eye E to be inspected through the objective lens 2.

The black dot glass 10 prevents the light reflected by the objective lens 2 from being reflected in the captured image, and a small light-shielding object is arranged at the center of the glass, that is, at a position where the optical axis is located. The light from the focus target projection system 9 is incident on the focus dot mirror 8 between the black dot glass 10 and the relay lens 7 at an angle at which the reflected light coincides with the optical axis of the relay lens 7. The focus optotype projection system 9 projects the focus optotype on the fundus of the eye E to be inspected. Therefore, in addition to the light emitted by the photographing illumination 14 and the observation illumination 15, the light of the focus target emitted by the focus target projection system 9 is incident on the fundus of the eye E to be inspected. The focus optotype projection system 9 has an infrared LED (Light Emitting Diode) that emits infrared light having a peak wavelength different from that of the infrared light for observing the fundus emitted by the observation illumination 15. When an infrared LED that emits infrared light having a peak wavelength of 850 nm is used as a light source for the observation illumination 15, for example, infrared light having a peak wavelength of 805 nm is used as the light source of the focus optotype projection system 9. An infrared LED that emits light is used.

The reflected light from the fundus of the eye to be inspected E illuminated by the light of the photographing illumination 14 and the observation illumination 15 passes through the objective lens 2, the perforated mirror 3, and the focus lens 4 and is incident on the half mirror 5. The half mirror 5 is fixed in the fundus photography device 1 at an appropriate tilt angle with respect to the optical axis of the objective lens 2. Therefore, the light reflected from the fundus of the eye E to be inspected is reflected by the half mirror 5 at an appropriate angle with respect to the optical axis of the objective lens 2. An imaging lens 16, an optical path correction glass 19, and an image sensor 20 are sequentially provided on the optical axis of the reflected light of the half mirror 5 incident from the focus lens 4. Then, a narrow-angle lens 17 or a wide-angle lens 18, which is a variable magnification lens appropriately selected according to the magnification desired by the observer, is inserted between the imaging lens 16 and the optical path correction glass 19. Therefore, the light reflected from the fundus of the eye E to be inspected passes through the imaging lens 16 after being reflected by the half mirror 5, passes through the narrow-angle lens 17 or the wide-angle lens 18, and then enters the image sensor 20. In the image sensor 20, photoelectric conversion elements arranged in a matrix receive light energy to generate an electric signal, and an image of the fundus of the eye E to be inspected is obtained.

The image sensor 20 is an image pickup device having sensitivity to at least visible light and infrared light. Therefore, the image sensor 20 can obtain an image of the fundus regardless of whether the light source for illuminating the fundus of the eye E to be examined is the photographing illumination 14 or the observation illumination 15. Further, the image sensor 20 is provided with a binning function for processing several adjacent photoelectric change elements together as one pixel. Therefore, the image sensor 20 exhibits a sensitivity that does not hinder the acquisition of a fundus image even in the reflected light from the fundus of the eye E to be inspected, which is illuminated by the observation illumination 15 having a lower illuminance than the imaging illumination 14. Is possible. Examples of such an image sensor 20 include CMOS.

By the way, the optical path correction glass 19 is inserted into the optical path when the fundus of the eye to be inspected E is photographed with visible light, and is pulled out from the optical path when observed with infrared light. The optical path correction glass 19 is a member that corrects the optical path difference between visible light and infrared light from the fundus of the eye to be inspected E to the image sensor 20, and is a combination of the fundus image of visible light and infrared light due to chromatic aberration. It is a plate-shaped glass prepared for the purpose of eliminating the deviation of the focal position. The optical path correction glass 19 preferably has a filter function for blocking infrared light. If the optical path correction glass 19 has a filter function for blocking infrared light, it is possible to prevent infrared light from being reflected in the captured image of the fundus. When the optical path correction glass 19 has a filter function, the optical path correction glass 19 can be inserted and removed instantly in order to suppress the time during which the fundus image due to infrared light is lost before and after shooting with visible light as much as possible. preferable.

FIG. 2 is a block diagram of an electric circuit provided in the fundus photography apparatus 1. The fundus photography apparatus 1 includes a CPU board 21, an LCD panel 22 (Liquid Crystal Display), an LCD backlight 23, an operation unit 24, and a main board 25. In FIG. 2, the actuator for moving the focus lens 4 and the optical path correction glass 19, the high-voltage circuit for emitting the shooting illumination 14, the LED provided in the focus target projection system 9, and the observation illumination 15 are all summarized as electronic components 26. Shows.

The CPU board 21 is a circuit board mainly responsible for processing images acquired by the image sensor 20, and is a CPU (Central Processing Unit) for processing images, an FPGA (Field Programmable Gate Array), and an SD card (SD card) for recording images. Various electronic components such as drives for (registered trademark) are mounted. The image sensor 20 operates in response to the control signal of the CPU board 21, and provides the acquired image to the CPU board 21. On the CPU board 21, various processes are performed on the image acquired by the image sensor 20, and the processed images are output to the LCD panel 22 or the SD card. On the LCD panel 22, the image output from the CPU board 21 is displayed.

The main board 25 is a circuit board that controls the entire fundus photography device 1, and is mounted with FPGA and various other electronic components. The main board 25 operates the CPU board 21 and the electronic components 26 according to the operation contents received by the operation unit 24. The main board 25 realizes the following processing flow.

FIG. 3 is a diagram showing a processing flow realized by the fundus photography apparatus 1. When the shooting start operation is performed by the operation unit 24, the binning function of the image sensor 20 is enabled and the binning process of the image sensor 20 is started (S101). Further, the observation illumination 15 is energized, and the infrared LED of the observation illumination 15 starts synchronous light emission (S102). Further, the infrared LED of the focus target projection system 9 starts emitting light (S103). Here, synchronous light emission means that light emission and extinguishing are repeated at the timing when the image sensor 20 scans one frame. Therefore, in the image of the eye E to be inspected acquired by the image sensor 20 during the synchronous emission of the observation illumination 15, the fundus image illuminated by the observation illumination 15 and the fundus image not illuminated by the observation illumination 15 are on the time axis. It is a set of images that are arranged alternately along the line. Since the infrared LED of the focus optotype projection system 9 constantly emits light even while the infrared LED of the observation illumination 15 emits synchronous light, the image sensor 20 acquires the subject during the synchronous emission of the observation illumination 15. The focus optotype is reflected in the image of the optometry E regardless of whether or not the fundus is illuminated by the observation illumination 15.

FIG. 4 is a diagram showing a timing chart of each process realized when the wide-angle lens 18 is selected. When the shooting start operation is performed with the wide-angle lens 18 selected, the binning process of the image sensor 20 is started and the infrared LED of the observation illumination 15 is started as shown in the timing chart of FIG. Synchronous light emission is started, and light emission of the infrared LED of the focus target projection system 9 is started. Therefore, the image sensor 20 acquires the following images.

FIG. 5 is a diagram showing an example of an image acquired by the image sensor 20. When the synchronized light emission by the infrared LED of the observation lighting 15 and the light emission of the infrared LED of the focus optotype projection system 9 are started by the shooting start operation, the image sensor 20 starts the observation lighting as shown in FIG. An image in which the fundus image illuminated by 15 (see even-numbered frames in FIG. 5) and the fundus image not illuminated by the observation illumination 15 (see odd-numbered frames in FIG. 5) are alternately repeated is acquired. Since the infrared LED of the focus optotype projection system 9 constantly emits light even while the infrared LED of the observation illumination 15 emits synchronous light, the image acquired by the image sensor 20 is as shown in FIG. , The focus optotype 30 is reflected over all the frames. In addition to the focus optotype 30, a WD index 31 (WD: Working Distance) is reflected in the image acquired by the image sensor 20.

FIG. 6 is a diagram showing an example of an image displayed on the LCD panel 22. When the image sensor 20 starts acquiring an image, the CPU board 21 performs a process of sending only the fundus image illuminated by the observation illumination 15 to the LCD panel 22. As a result, on the LCD panel 22, for example, as shown in FIG. 6, a continuous image of the fundus image illuminated by the observation illumination 15 is displayed. In this case, the images of the even-numbered frames are displayed at one interval such as the second frame, the fourth frame, the sixth frame, etc. shown in FIG. 5, but the images of all the target frames are not necessarily displayed. It is not necessary to display, and the second frame, the sixth frame, the tenth frame, and so on may be thinned out and displayed.

The processing after step S104 will be described with reference to the flowchart of FIG. 3 again. The fundus photography device 1 is provided with an autofocus function and an autoshot function, and can automatically adjust the focus lens 4 by electronic control. However, in the fundus photography apparatus 1 of the present embodiment, when the narrow-angle lens 17 is selected from the narrow-angle lens 17 and the wide-angle lens 18 appropriately selected by the observer according to the observation site, autofocus is performed. Disable the function and the auto shot function. The reason is that the optic disc, which is likely to be observed by selecting the narrow-angle lens 17, has a higher reflectance than the so-called fundus portion, so that the focus optotype is projected onto the optic disc. This is because the brightness of the lens becomes unstable compared to the fundus, and the autofocus function may not operate normally. Therefore, as shown in the flowchart of FIG. 3, in the fundus photography apparatus 1 of the present embodiment, when the wide-angle lens 18 is selected, the processing related to the autofocus function and the autoshot function (from step S105 described later). The process up to step S107) is performed, and when the narrow-angle lens 17 is selected, the process related to the manual focus function (processes from steps S108 to S109 described later) is performed.

That is, in the fundus photography apparatus 1, after the processing of step S103 is performed, it is determined whether or not the wide-angle lens 18 is selected (S104). If the wide-angle lens 18 is inserted between the imaging lens 16 and the optical path correction glass 19, an affirmative determination is made in the process of step S104. Further, if the narrow-angle lens 17 is inserted between the imaging lens 16 and the optical path correction glass 19, a negative determination is made in the process of step S104. Which of the wide-angle lens 18 and the narrow-angle lens 17 is selected is detected by a contact switch or the like provided in the lens switching mechanism.

After the affirmative determination is made in step S104, it is determined whether or not the focus is matched (S105), and if the focus is not matched, the motor of the focus lens 4 operates appropriately (S106). After step S106 is performed, the processes after step S104 are performed again. If it is determined in the process of step S105 that the focus is met, then it is determined whether or not the position and size of the WD index 31 are within the specified range (S107).

Further, after the negative determination is made in step S104, the autofocus function and the autoshot function are disabled (S108), and it is determined whether or not the shutter switch is pressed by the operation unit 24 (S109).

By the way, in step S105, the determination process is performed as follows. That is, when the image sensor 20 starts acquiring an image, the CPU board 21 is illuminated by the observation illumination 15 in addition to the process of sending only the fundus image illuminated by the observation illumination 15 to the LCD panel 22 as described above. Detection processing of the focus optotype 30 is performed using the untouched fundus image. FIG. 7 is a diagram showing an example of an image in which fundus images used for the detection process of the focus optotype 30 are arranged. In the process of determining whether or not the focus is matched, which is performed in step S105, a fundus image in which the fundus is not reflected in the background of the focus target 30 is used in order to facilitate the detection of the focus target 30. In this case, the images of the odd-numbered frames are displayed at one interval such as the first frame, the third frame, the fifth frame, etc. shown in FIG. 5, but the images of all the target frames are not necessarily displayed. It is not necessary to display the above, and the first frame, the fifth frame, the ninth frame, and the like may be thinned out and used.

Whether or not the focus is met is determined as follows. FIG. 8 is a first diagram showing a method of determining focus. In determining whether or not the focus is met, first, as shown in FIG. 8, the positions (y coordinates) of the upper and lower ends of the focus optotype 30L within the determination range 32L on the left side and the determination range 32R on the right side. The positions (y coordinates) of the upper and lower ends of the focus optotype 30R in the above are extracted.

FIG. 9 is a second diagram showing a method of determining focus. The positions of the upper and lower ends of the focus optotypes 30L and 30R within the determination range 32L and 32R are acquired, for example, as follows. That is, the sum of the luminance of adjacent 10 pixels in the x-axis direction is calculated for each y coordinate, and the coordinates of the portion where the sum of the luminance is 75% of the peak of the luminance are the coordinates of the upper end and the lower end of the focus optotypes 30L and 30R. Get as coordinates.

FIG. 10 is a third diagram showing a method for determining focus. After the coordinates of the upper end and the lower end of the focus optotypes 30L and 30R within the determination range 32L and 32R are acquired, the center y coordinates of the upper end and the lower end are calculated for each of the focus optotype 30L and the focus optotype 30R. Will be. If the difference between the center y coordinate of the focus target 30L and the center y coordinate of the focus target 30R is not 0, a negative determination is made in step S105, and the focus lens 4 is set to 0 so that the difference becomes 0. The motor is moved appropriately. If the difference is 0, an affirmative determination is made in step S105.

In the present embodiment, as described above, the autofocus function and the autoshot function are enabled when the wide-angle lens 18 is selected, but the fundus photography device 1 is not limited to this. The fundus photography apparatus 1 may, for example, realize the above-mentioned processes from step S105 to step S107 regardless of whether or not the wide-angle lens 18 is selected, or may have an autofocus function and an autofocus function. The auto-shot function may be abolished so that the above-mentioned processes from step S108 to step S109 can be realized even while the wide-angle lens 18 is being selected. When the processing from step S105 to step S107 is realized even while the narrow angle lens 17 is being selected as in the former case, for example, the infrared of the focus optotype projection system 9 is being selected while the narrow angle lens 17 is being selected. By reducing the brightness of the LED, it is possible to change the brightness of the focus optotype projected on the optic nerve head and suppress the possibility that the autofocus function does not operate normally.

The processing after step S110 will be described with reference to the flowchart of FIG. 3 again. After the affirmative determination is made in the process of step S107 or step S109, preparations for fundus photography are performed in order to obtain a clear high-resolution image of the fundus illuminated by the photographing illumination 14 having sufficient brightness. Will be. That is, the binning process of the image sensor 20 is stopped (S110), the observation illumination 15 is turned off (S111), and the infrared LED of the focus target projection system 9 is turned off (S112). Then, the optical path correction glass 19 is inserted between the wide-angle lens 18 and the image sensor 20 (S113), and the image sensor 20 photographs the fundus at the same time as the light emission of the photographing illumination 14 (S114).

The optical path correction glass 19 is inserted for the following reasons. FIG. 11 is a first diagram comparing the in-focus positions. In the optical system included in the fundus photography apparatus 1, chromatic aberration is an element that cannot be ignored in clearly photographing the fundus. For example, when the position of the focus lens 4 is adjusted by infrared light as shown in FIG. 11A, the optical path correction glass 19 is visible when it is not inserted between the wide-angle lens 18 and the image sensor 20. The light is focused at a position away from the image sensor 20 as shown in FIG. 11 (B). On the other hand, when the optical path correction glass 19 whose thickness and material are selected in consideration of the chromatic aberration between infrared light and visible light is inserted between the wide-angle lens 18 and the image sensor 20, the visible light is shown in FIG. Focus on the surface of the image sensor 20 as shown by (C). Therefore, the image sensor 20 can capture a clear image of the fundus illuminated by the photographing illumination 14 that emits visible light.

The contents of the processing realized by the fundus photography apparatus 1 when the wide-angle lens 18 is selected are as described above. Next, the contents of the processing realized by the fundus photography apparatus 1 when the narrow angle lens 17 is selected will be described.

FIG. 12 is a diagram showing a timing chart of each process realized when the narrow angle lens 17 is selected. When the shooting start operation is performed with the narrow-angle lens 17 selected, the binning process of the image sensor 20, the synchronous emission of the observation illumination 15, and the focus optotype projection are performed as shown in the timing chart of FIG. The light emission of the system 9 is started, and a continuous image of the fundus image illuminated by the observation illumination 15 is displayed on the LCD panel 22. Then, as shown in the flowchart of FIG. 3, a negative determination is made in the process of step S104, and the autofocus function and the autoshot function are invalidated (S108). Then, the operation unit 24 determines whether or not the shutter switch has been pressed (S109), and when an affirmative determination is made in step S109, a series of processes from step S110 to step S114 is executed to take a picture of the fundus. Is completed.

FIG. 13 is a second diagram comparing the in-focus positions. When the narrow-angle lens 17 is selected, chromatic aberration in the optical system included in the fundus photography device 1 becomes remarkable as compared with the case where the wide-angle lens 18 is selected. That is, as can be seen by comparing the in-focus position shown in FIG. 11 with the in-focus position shown in FIG. 13, when the narrow-angle lens 17 is selected, the position of the focus lens 4 is adjusted by infrared light. In this state (see FIG. 13 (A)), the visible light is in focus at a position far away from the image sensor 20 as shown in FIG. 13 (B). Therefore, the optical path correction glass 19 inserted between the wide-angle lens 18 and the image sensor 20 when the narrow-angle lens 17 is selected is the wide-angle lens 18 when the wide-angle lens 18 is selected. The optical path correction glass 19 inserted between the image sensor 20 and the image sensor 20 may have a different thickness or refractive index. If the optical path correction glass 19 is switched according to the characteristics of the lens arranged between the image forming lens 16 and the optical path correction glass 19, visible light is transmitted to the image sensor 20 as shown in FIG. 13 (C). Can be focused on the surface.

The description of the fundus photography device 1 is as described above, but the fundus photography device 1 is not limited to the above-mentioned form. The fundus photography apparatus 1 may be equipped with, for example, an infrared LED that emits infrared light having a wavelength other than the above-mentioned wavelength in the focus target projection system 9 or the observation illumination 15. Further, in the fundus photography device 1, for example, the perforated mirror 3 or the half mirror 5 may tilt the optical axis at an angle different from the optical axis shown in FIG.

1 ・ ・ Fundus photography device: 2 ・ ・ Objective lens: 3 ・ ・ Perforated mirror: 4 ・ ・ Focus lens: 5 ・ ・ Half mirror: 6 ・ ・ Internal fixation light: 7 ・ ・ Relay lens: 8 ・ ・ Focus Dot mirror: 9 ・ ・ Focus optotype projection system: 10 ・ ・ Black dot glass: 11 ・ ・ Relay lens: 12 ・ ・ Ring slit: 13 ・ ・ Diffuse plate: 14 ・ ・ Shooting lighting: 15 ・ ・ Observation lighting: 16 ・ ・ Imaging lens: 17 ・ ・ Narrow angle lens: 18 ・ ・ Wide angle lens: 19 ・ ・ Optical path correction glass: 20 ・ ・ Image sensor: 21 ・ ・ CPU board: 22 ・ ・ LCD panel: 23 ・ ・LCD backlight: 24 ... Operation unit: 25 ... Main board: 26 ... Electronic parts: 30, 30L, 30R ... Focus target: 31 ... WD index: 32L, 32R ... Judgment range: E ...・ Eye to be inspected

Claims (6)

An image sensor that is sensitive to at least visible and invisible light,
A focus lens placed in the middle of the optical path from the fundus of the subject's eye to the image sensor,
A position where the focus optotype is projected by a second invisible light having a peak wavelength different from that of the first invisible light used for observing the fundus of the subject's eye, and the image of the focus optotype obtained by the image sensor is in focus. Focus adjustment means for aligning the focus lens with
It is provided with an optical path correction member that is inserted and removed when the subject's eye fundus is photographed with visible light and corrects the optical path difference between the visible light and the invisible light from the subject's eye fundus to the image pickup element .
The focus adjusting means is an image of the focus optotype obtained by the image sensor when the first invisible light is turned off during fundus observation performed by blinking the first invisible light every frame. A fundus photography device that aligns the focus lens with the position where the light is in focus . The fundus image obtained by the image pickup device when the first invisible light is turned on is selectively displayed on the display.
The fundus photography apparatus according to claim 1. The optical path correction member has a function of blocking invisible light.
The fundus photography apparatus according to claim 1 or 2 . The fundus photography apparatus includes a plurality of the optical path correction members corresponding to the plurality of types of lenses exchanged according to the magnification.
The fundus photography apparatus according to any one of claims 1 to 3 . The invisible light is infrared light,
The fundus photography apparatus according to any one of claims 1 to 4 . The first invisible light is infrared light having a wavelength of 850 nm as a peak.
The second invisible light is infrared light having a wavelength of 805 nm as a peak.
The fundus photography apparatus according to any one of claims 1 to 5 .

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