WO2018186469A1

WO2018186469A1 - Fundus photography device

Info

Publication number: WO2018186469A1
Application number: PCT/JP2018/014581
Authority: WO
Inventors: 和典松村; 希鳥羽; 加藤　洋一; 佑介井澤; 貴紀山内
Original assignee: 興和株式会社
Priority date: 2017-04-06
Filing date: 2018-04-05
Publication date: 2018-10-11
Also published as: JPWO2018186469A1; JP7094268B2; TW201838582A

Abstract

The present application discloses a fundus photography device with which position adjustment of a focus lens using invisible light, which is performed prior to performing fundus photography using visible light, can be performed without requiring complex control. The present invention provides a fundus photography device provided with: an image capture element sensitive to at least visible light and invisible light; a focus lens disposed partway along an optical path extending from the fundus of a subject's eye to the image capture element; a focus adjust means which projects a focus target using a second invisible light having a different peak wavelength from that of a first invisible light used for observing the fundus of the subject's eye, and which aligns the focus lens in a position at which a focus target image captured by means of the image capture element is focused; and an optical path correction member which is inserted or removed when an image of the fundus of the subject's eye is captured using visible light, and which corrects an optical path difference between visible light and invisible light traveling from the fundus of the subject's eye to the image capture element.

Description

Fundus photographing device

The present invention relates to a fundus imaging apparatus.

In fundus photography using visible light, in order to prevent the pupil from closing with visible light irradiating the fundus, pre-adjustment of the eye to be examined and the optical system using invisible light such as infrared light that the eye does not sense (optical axis alignment) , Focusing, etc.) are performed (for example, see Patent Document 1).

Japanese Patent No. 5807701 Japanese Patent No. 5215675 International Publication No. 2016/136859

In the fundus imaging apparatus, the position of the focus lens is adjusted prior to fundus imaging. 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 position shift of the focus lens due to chromatic aberration. However, adjusting the position of the focus lens according to chromatic aberration complicates the control of the operating mechanism of the focus lens.

Therefore, the present application discloses a fundus imaging apparatus capable of realizing the position adjustment of the focus lens using invisible light performed prior to fundus imaging with visible light without requiring complicated control.

In order to solve the above problems, in the present invention, an imaging device having sensitivity to at least visible light and invisible light is used, and when the fundus is photographed using visible light, the focus lens is adjusted to a position where the invisible light is focused. Decided to do it. The optical path difference between visible light and invisible light is corrected by inserting and removing the optical path correction member.

Specifically, the present invention relates to a fundus imaging apparatus, an imaging device having sensitivity to at least visible light and invisible light, a focus lens disposed in the optical path from the subject eye fundus to the imaging device, and a subject eye The focus target is projected with the second invisible light having a peak wavelength different from that of the first invisible light used for observing the fundus, and the focus lens is adjusted to a position where the image of the focus target obtained by the image sensor is in focus. A focus adjustment unit; and an optical path correction member that is inserted and removed when the subject eye fundus is imaged with visible light and corrects an optical path difference between visible light and invisible light from the subject eye fundus to the imaging device.

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

The focus adjusting means of the fundus photographing apparatus adjusts the focus lens to a position where the image of the focus target projected with the second invisible light is in focus. Then, photographing of the fundus using visible light is performed while keeping the focus lens in the position where the invisible light is focused. That is, in the operation mechanism of the focus lens, complicated control in consideration of chromatic aberration between visible light and invisible light is not performed. The in-focus position caused by chromatic aberration between visible light and invisible light is adjusted by an optical path correction member that is inserted and removed during fundus photography using 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 adjusting the position of the focus lens in consideration of chromatic aberration.

Note that the focus adjustment unit may adjust the focus lens to a position where the image of the focus target obtained by the image sensor is in focus when the first invisible light is turned off. If the above fundus imaging apparatus includes such a focus adjustment unit, the focus target can be clearly captured.

In addition, the focus adjustment unit described above can generate an image of the focus target obtained by the imaging device when the first invisible light is turned off during fundus observation performed by blinking the first invisible light every frame. The focus lens may be adjusted to the position to be focused. If the above fundus imaging apparatus includes such a focus adjustment unit, focus adjustment is performed during fundus observation.

Further, the optical path correction member may have a function of blocking invisible light. If the fundus photographing apparatus includes the optical path correction member, invisible light is not reflected in the fundus photographed image, and thus a clear fundus photographed image can be obtained.

Further, the above fundus imaging apparatus may include a plurality of optical path correction members respectively corresponding to a plurality of types of lenses that are exchanged according to the magnification. If the above-described fundus imaging apparatus includes such an optical path correction member, a clearer fundus image can be obtained.

With the above fundus photographing apparatus, the position adjustment of the focus lens using invisible light performed prior to fundus photographing with visible light can be realized without requiring complicated control.

FIG. 1 is a diagram illustrating a schematic configuration of an optical system of a fundus imaging apparatus according to the present embodiment. FIG. 2 is a block diagram of an electric circuit provided in the fundus imaging apparatus. FIG. 3 is a diagram illustrating a processing flow realized by the fundus imaging apparatus. FIG. 4 is a diagram illustrating a timing chart of each process realized when the wide-angle lens is selected. FIG. 5 is a diagram illustrating 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 illustrating an example of a video in which fundus images are used for focus target detection processing. FIG. 8 is a first diagram illustrating a focus determination method. FIG. 9 is a second diagram illustrating the focus determination method. FIG. 10 is a third diagram illustrating the focus determination method. FIG. 11 is a first diagram comparing in-focus positions. FIG. 12 is a diagram illustrating a timing chart of each process realized when the narrow-angle lens is selected. FIG. 13 is a second diagram comparing in-focus positions.

Hereinafter, embodiments of the present invention will be described. Embodiment shown below is an example of embodiment of this invention, and does not limit the technical scope of this invention to the following aspects.

FIG. 1 is a diagram showing a schematic configuration of an optical system of the fundus imaging apparatus of the present embodiment. The fundus imaging apparatus 1 is an apparatus for imaging the fundus of the eye 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, a focus dot mirror 8, Focus target projection system 9, black spot plate glass 10, relay lens 11, ring slit 12, diffuser plate 13, photographing illumination 14, observation illumination 15, imaging lens 16, narrow angle lens 17, wide angle lens 18, optical path A correction glass 19 (an example of an “optical path correction member” in the present application) and an image sensor 20 are provided.

First, the positional relationship and function of each component provided in the fundus imaging apparatus 1 will be described. The objective lens 2 is a lens located in front of the eye E to be examined. On the optical axis behind the objective lens 2, a perforated mirror 3, a focus lens 4, a half mirror 5, and an internal fixation lamp 6 are arranged in this order. The perforated mirror 3 is a mirror in which a through hole is formed at a portion through which the optical axis of the objective lens 2 passes, and is fixed in the fundus photographing apparatus 1 at an appropriate inclination 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 applied to the eye E, the relay lens 7, the focus dot mirror 8, the black dot plate glass 10, the relay lens 11, in that order from the perforated mirror 3 side. A ring slit 12, a diffusing plate 13, a photographing illumination 14, and an observation illumination 15 are arranged. Therefore, the light emitted from the photographing illumination 14 and the observation illumination 15 becomes an annular irradiation light in the process of passing through the diffusion plate 13 and the ring slit 12, and the relay lens 11, the black dot plate glass 10, the focus dot mirror 8, and the relay. The light is reflected by the perforated mirror 3 through the lens 7, and illuminates the fundus of the eye E through the objective lens 2.

The black spot plate glass 10 prevents the reflected light from the objective lens 2 from appearing in the photographed image, and a small light blocking object is disposed at the center of the plate glass, that is, at a position where the optical axis is located. Light from the focus target projection system 9 is incident on the focus dot mirror 8 between the black spot plate 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 target projection system 9 projects the focus target on the fundus of the eye E. Therefore, in addition to the light emitted from the photographing illumination 14 and the observation illumination 15, the light of the focus target emitted from the focus target projection system 9 enters the fundus of the eye E. The focus target projection system 9 includes an infrared LED (Light Emitting Diode) that emits infrared light having a peak wavelength different from that of infrared light for fundus observation emitted by the observation illumination 15. When an infrared LED that emits infrared light having a peak wavelength of 850 nm is used as the light source for observation 15, for example, infrared light having a peak wavelength of 805 nm is used as the light source of the focus target projection system 9. An infrared LED that emits light is used.

Reflected light from the fundus of the subject eye E illuminated with light from the imaging illumination 14 or observation illumination 15 passes through the objective lens 2, the perforated mirror 3, and the focus lens 4 and enters the half mirror 5. The half mirror 5 is fixed in the fundus photographing apparatus 1 at an appropriate inclination angle with respect to the optical axis of the objective lens 2. Therefore, the reflected light from the fundus of the eye E 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. A narrow-angle lens 17 or a wide-angle lens 18, which is a variable power lens that is 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 reflected light from the fundus of the eye E is reflected by the half mirror 5, passes through the imaging lens 16, 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, the photoelectric conversion elements arranged in a matrix form receive an energy of light and emit an electric signal, and an image of the fundus of the eye E is obtained.

The image sensor 20 is an image sensor 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 is the photographing illumination 14 or the observation illumination 15. Further, the image sensor 20 has a binning function for processing several adjacent photoelectric change elements as one pixel. Therefore, the image sensor 20 exhibits sensitivity that does not hinder obtaining a fundus image even in the reflected light from the fundus of the eye E to be examined, which is illuminated by the observation illumination 15 having a lower illuminance than the imaging illumination 14. Is possible. An example of such an image sensor 20 is a CMOS.

Incidentally, the optical path correction glass 19 is inserted into the optical path when photographing the fundus of the eye E to be examined with visible light, and is pulled out of the optical path during observation with infrared light. The optical path correction glass 19 is a member that corrects an optical path difference between visible light and infrared light from the fundus of the eye E to the image sensor 20, and combines the fundus image of visible light and infrared light due to chromatic aberration. It is a plate-like glass prepared for the purpose of eliminating the shift 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 fundus image. When the optical path correction glass 19 has a filter function, the optical path correction glass 19 can be inserted and removed instantaneously in order to suppress as much as possible the time during which the fundus image due to infrared light is lost before and after photographing with visible light. preferable.

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

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

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

FIG. 3 is a diagram illustrating a processing flow realized by the fundus imaging apparatus 1. When a shooting start operation is performed at 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). In addition, 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 to emit light (S103). Here, the synchronized light emission means that the image sensor 20 repeats light emission and extinction in accordance with the timing of scanning one frame. Therefore, the image of the eye E to be inspected acquired by the image sensor 20 during the synchronized light emission of the observation illumination 15 includes the fundus image illuminated with the observation illumination 15 and the fundus image not illuminated with the observation illumination 15 on the time axis. It becomes a set of images arranged alternately along. Since the infrared LED of the focus target projection system 9 always emits light while the infrared LED of the observation illumination 15 emits light synchronously, the image sensor 20 acquires during the synchronous light emission of the observation illumination 15. Regardless of whether or not the fundus is illuminated with the observation illumination 15, the focus target is reflected in the image of the optometry E.

FIG. 4 is a diagram showing a timing chart of each process realized when the wide-angle lens 18 is selected. When the photographing start operation is performed in a state where the wide-angle lens 18 is selected, the binning process of the image sensor 20 is started as shown in the timing chart of FIG. Is started, and the infrared LED of the focus target projection system 9 starts to emit light. Therefore, the image sensor 20 acquires the following video.

FIG. 5 is a diagram illustrating an example of a video acquired by the image sensor 20. When the synchronous light emission by the infrared LED of the observation illumination 15 and the emission of the infrared LED of the focus target projection system 9 are started by the photographing start operation, the image sensor 20 has the observation illumination as shown in FIG. 15 is obtained by alternately repeating the fundus image illuminated by 15 (see the even frame in FIG. 5) and the fundus image not illuminated by the observation illumination 15 (see the odd frame in FIG. 5). Since the infrared LED of the focus target projection system 9 always emits light while the infrared LED of the observation illumination 15 emits light synchronously, the image acquired by the image sensor 20 is as shown in FIG. The focus target 30 is reflected over all frames. In addition to the focus target 30, the WD index 31 (WD: Working Distance) is reflected in the video 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 images, the CPU substrate 21 performs processing for sending only the fundus image illuminated by the observation illumination 15 to the LCD panel 22. Thereby, for example, as shown in FIG. 6, the LCD panel 22 displays an image in which the fundus image illuminated by the observation illumination 15 is continuous. In this case, the second frame, the fourth frame, the sixth frame, and so on shown in FIG. 5 are displayed at even intervals, and the images of all the target frames are displayed. There is no need to display the frame, and the second frame, the sixth frame, and the tenth frame may be displayed in a thinned-out manner.

The processing after step S104 will be described with reference to the flowchart of FIG. The fundus imaging apparatus 1 has an autofocus function and an autoshot function, and can automatically adjust the focus lens 4 by electronic control. However, in the fundus imaging apparatus 1 according to the present embodiment, when the narrow-angle lens 17 is selected from the narrow-angle lens 17 and the wide-angle lens 18 that are appropriately selected by the observer according to the observation site, autofocusing is performed. Disable function and auto shot function. The reason is that the optic nerve head that is likely to be observed by selecting the narrow-angle lens 17 has a higher reflectance than the so-called fundus portion. Therefore, when the focus target is projected onto the optic nerve head, the focus target is projected. This is because the brightness of the camera 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 imaging apparatus 1 of the present embodiment, when the wide-angle lens 18 is selected, processing related to the autofocus function and the autoshot function (from step S105 described later). If the narrow-angle lens 17 is selected, processing related to the manual focus function (processing from step S108 to step S109 described later) is performed.

That is, in the fundus imaging apparatus 1, after the process 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, a positive determination is made in the process of step S104. 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 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). If the focus is not matched, the motor of the focus lens 4 operates as appropriate (S106). After step S106 is performed, the processing after step S104 is performed again. If it is determined in step S105 that the focus is matched, it is next determined whether or not the position and size of the WD index 31 are within a specified range (S107).

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

Incidentally, in step S105, determination processing is performed as follows. That is, when the image sensor 20 starts acquiring images, the CPU board 21 is illuminated with the observation illumination 15 in addition to the process of sending only the fundus image illuminated with the observation illumination 15 to the LCD panel 22 as described above. Detection processing of the focus target 30 using a fundus image that has not been performed is performed. FIG. 7 is a diagram illustrating an example of a video in which fundus images used for the process of detecting the focus target 30 are arranged. In the process of determining whether the focus is matched in step S105, a fundus image in which the fundus is not reflected in the background of the focus target 30 is used to facilitate detection of the focus target 30. In this case, the first frame, the third frame, the fifth frame, and so on shown in FIG. 5 are displayed with odd-numbered frames at one interval, but the images of all target frames are not necessarily displayed. There is no need to display the image, and the first frame, the fifth frame, and the ninth frame may be used by being thinned.

Whether or not the focus is in agreement is determined as follows. FIG. 8 is a first diagram illustrating a focus determination method. In determining whether or not the focus is matched, first, as shown in FIG. 8, the upper and lower positions (y coordinates) of the focus target 30L in the left determination range 32L and the right determination range 32R. The positions (y coordinates) of the upper and lower ends of the focus target 30R are extracted.

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

FIG. 10 is a third diagram illustrating the focus determination method. After the coordinates of the upper and lower ends of the focus targets 30L and 30R within the determination ranges 32L and 32R are acquired, the center y coordinates of the upper and lower ends are calculated for the focus target 30L and the focus target 30R, respectively. Is called. 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 zero, a negative determination is made in step S105, and the focus lens 4 is adjusted in step S106 so that the difference becomes zero. The motor is moved accordingly. 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 effective when the wide-angle lens 18 is selected, but the fundus imaging apparatus 1 is not limited to this. For example, the fundus imaging apparatus 1 may realize the processing from the above-described step S105 to step S107 regardless of whether or not the wide-angle lens 18 is selected, or the autofocus function and The auto-shot function may be eliminated and the processing from step S108 to step S109 described above may be realized while the wide-angle lens 18 is selected. When the processing from step S105 to step S107 is performed even when the narrow-angle lens 17 is selected as in the former case, for example, when the narrow-angle lens 17 is selected, the infrared of the focus target projection system 9 is selected. It is conceivable that the brightness of the focus target projected on the optic nerve head is changed by reducing the brightness of the LED, and the possibility that the autofocus function does not operate normally is suppressed.

The processing after step S110 will be described with reference to the flowchart of FIG. After an affirmative determination is made in step S107 or step S109 above, preparation for fundus photography is performed in order to obtain a clear, high-resolution image of the fundus illuminated by the photographing illumination 14 having sufficient luminance. Is called. 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 simultaneously with the light emission of the photographing illumination 14 (S114).

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

The contents of the processing realized by the fundus imaging apparatus 1 when the wide-angle lens 18 is selected are as described above. Next, the contents of processing realized by the fundus imaging 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 a shooting start operation is performed with the narrow-angle lens 17 selected, as shown in the timing chart of FIG. 12, the binning process of the image sensor 20, the synchronous light emission of the observation illumination 15, and the focus target projection The light emission of the system 9 is started, and an image in which the fundus image illuminated by the observation illumination 15 is continuous 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, it is determined whether or not the shutter switch has been pressed by the operation unit 24 (S109). If an affirmative determination is made in step S109, a series of processing from step S110 to step S114 is executed, and the fundus is photographed. Is completed.

FIG. 13 is a second diagram comparing in-focus positions. When the narrow-angle lens 17 is selected, chromatic aberration in the optical system of the fundus photographing apparatus 1 becomes more prominent than when 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 with infrared light. In this state (see FIG. 13A), the visible light is focused at a position far away from the image sensor 20 as shown in FIG. 13B. 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 disposed between the imaging lens 16 and the optical path correction glass 19, visible light is converted into the image sensor 20 as shown in FIG. Can focus on the surface.

The description of the fundus imaging apparatus 1 is as described above, but the fundus imaging apparatus 1 is not limited to the above form. The fundus photographing apparatus 1 may include, for example, an infrared LED that emits infrared light other than the above-described wavelengths in the focus target projection system 9 and the observation illumination 15. In addition, for example, the fundus imaging apparatus 1 may be configured such that the perforated mirror 3 and the half mirror 5 tilt the optical axis at an angle different from the optical axis shown in FIG.

1. Fundus photographing device: 2. Objective lens: 3. Perforated mirror: 4. Focus lens: 5. Half mirror: 6. Internal fixation lamp: 7. Relay lens: 8. Focus Dot mirror: 9. Focus target projection system: 10. Black spot plate glass: 11. Relay lens: 12. Ring slit: 13. Diffuser plate: 14. Imaging illumination: 15. Observation illumination: 16. Image forming 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 Determination range: E -Eye to be examined

Claims

An image sensor having sensitivity to at least visible light and invisible light; and
A focus lens arranged in the middle of the optical path from the subject's eye fundus to the image sensor;
A position at which the focus target is projected with the 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 target obtained by the imaging element is focused. Focus adjusting means for aligning the focus lens with
An optical path correction member that is inserted and removed when imaging the fundus of the subject's eye with visible light and corrects an optical path difference between visible light and invisible light that reaches the imaging device from the fundus of the subject's eye.
Fundus photographing device.
The focus adjustment unit adjusts the focus lens to a position where an image of the focus target obtained by the imaging element is in focus when the first invisible light is turned off.
The fundus imaging apparatus according to claim 1.
The focus adjustment unit is configured to obtain an image of the focus target obtained by the imaging device when the first invisible light is turned off during fundus observation performed by blinking the first invisible light every frame. Align the focus lens at the position where the
The fundus imaging apparatus according to claim 1 or 2.
The optical path correction member has a function of blocking invisible light,
The fundus imaging apparatus according to any one of claims 1 to 3.
The fundus imaging apparatus includes a plurality of the optical path correction members respectively corresponding to a plurality of types of lenses exchanged according to magnification.
The fundus imaging apparatus according to any one of claims 1 to 4.
The invisible light is infrared light.
The fundus imaging apparatus according to any one of claims 1 to 5.
The first invisible light is infrared light having a peak at a wavelength of 850 nm,
The second invisible light is infrared light having a peak at a wavelength of 805 nm.
The fundus imaging apparatus according to any one of claims 1 to 6.