JP2022060798A - Ocular fundus imaging apparatus - Google Patents

Abstract

To acquire a clearer ocular fundus image with a simple configuration even when using imaging lights of a plurality of different wavelengths in ocular fundus imaging.SOLUTION: An ocular fundus imaging apparatus includes irradiation means for irradiating the ocular fundus with an imaging light emitted from a light source through focus means, light reception means for receiving a return light from the ocular fundus, generation means for generating an image of the ocular fundus on the basis of the received return light, and control means for controlling the adjustment of the focus means and the light source. The control means executes control so that an imaging light of a first wavelength is emitted, executes adjustment so that the imaging light of the first wavelength is focused at a predetermined position in a depth direction, changes the imaging light of the first wavelength to an imaging light of a second wavelength, and executes adjustment so that the imaging light of the second wavelength is focused at a predetermined position of the ocular fundus. The generation means generates a first ocular fundus image by the return light of the imaging light of the first wavelength, and a second ocular fundus image by the return light of the imaging light of the second wavelength.SELECTED DRAWING: Figure 6

Description

The present invention relates to a fundus photography apparatus and a control method thereof.

Currently, in the field of ophthalmology, a device (hereinafter referred to as an SLO device) using a scanning laser ophthalmoscope (SLO) that photographs the fundus of the eye to be inspected by scanning a laser has been put into practical use. This makes it possible to capture a fundus image of the eye to be inspected at a higher resolution than a conventional fundus camera.

In the SLO device, the light from the light source is irradiated by a galvano mirror or the like so as to scan on the fundus of the eye to be inspected. The reflected light from the fundus of the eye to be inspected is separated from the illumination optical path by a perforated mirror or the like and guided to the light receiving element. By detecting the intensity of the reflected light with the light receiving element, a two-dimensional surface image of the fundus of the eye to be inspected can be obtained. When acquiring a color fundus image, a color SLO device including a plurality of light sources having different center wavelengths has been proposed.

The color SLO device has an optical path common to each wavelength for scanning the inside of the eye to be inspected by a galvano mirror or the like and irradiating the eye to be inspected from the objective lens. The reflected light from the inside of the eye to be inspected passes through a common optical path, passes through a light receiving optical path separated from the projected optical path from the light source by a perforated mirror or the like, and is received by each light receiving element. A two-dimensional color image of the eye to be inspected can be obtained by image processing the received light intensity.

Japanese Unexamined Patent Publication No. 2019-63243 Japanese Unexamined Patent Publication No. 2020-22569

In Patent Document 1, in the SLO apparatus, the amount of chromatic aberration of magnification due to the difference in the shooting angle of view is corrected through signal processing. In Patent Document 1, the imaging optical system of each wavelength is common, and it is assumed that imaging is performed with a deviation of the focus position at the fundus of the eye to be inspected due to each wavelength.

Patent Document 2 discloses that a lens for chromatic aberration correction is arranged in an optical path on the long wavelength side, which is greatly affected by chromatic aberration, for chromatic aberration correction of a wide band wavelength in a multifunction device of an SLO device and an OCT device. In Patent Document 2, a special chromatic aberration correction lens is arranged outside the common optical path having a wide band wavelength, and it is difficult to simplify the apparatus.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain a clearer fundus image with a simple configuration even when a plurality of different wavelengths of light are used for fundus photography.

In view of the above problems, the fundus photography apparatus according to the embodiment of the present invention is
The irradiation means that irradiates the subject eye with the photographing light emitted from the light source via the focusing means, the light receiving portion that receives the return light of the photographing light from the subject eye, and the light receiving portion based on the received return light. It has a generation means for generating an image of the fundus of the eye to be inspected, a control means for adjusting the focus means, and a control means for controlling the light source, and the control means emits the photographing light having the first wavelength from the light source. The focusing means is adjusted so that the photographing light of the first wavelength is focused on a predetermined position in the depth direction of the fundus, and the photographing of the first wavelength emitted from the light source is performed. The focusing means is adjusted so that the shooting light of the second wavelength is focused on the predetermined position of the fundus while changing the light to the shooting light of the second wavelength, and the generation means is the first. An image of the first fundus due to the return light of the photographing light having the same wavelength and an image of the second fundus due to the return light of the photographing light having the second wavelength are generated.

According to the present invention, a clearer fundus image can be obtained with a simple configuration even when a plurality of different wavelengths of light are used for fundus photography.

It is a figure which shows the schematic optical composition of the SLO apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the structure of the control part used in the SLO apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the appearance of the SLO apparatus which concerns on 1st Embodiment of this invention. It is a figure explaining the screen which is displayed on the display part which concerns on 1st Embodiment of this invention. It is a flowchart explaining the photography flow which concerns on 1st Embodiment of this invention. It is a flowchart explaining the detailed flow at the time of photography which concerns on 1st Embodiment of this invention. It is a figure which shows the focus lens drive at the time of photographing which concerns on 1st Embodiment of this invention. It is a flowchart explaining the detailed flow at the time of photographing in the case of the minimum offset amount which concerns on 1st Embodiment of this invention. It is a flowchart explaining the detailed flow at the time of a plurality of frames shooting which concerns on 1st Embodiment of this invention. It is a figure which shows the focus lens drive at the time of photographing which concerns on the modification of 1st Embodiment of this invention. It is a figure which shows the shooting angle of view which concerns on the modification of 1st Embodiment of this invention. It is a figure which shows the schematic optical composition of the SLO apparatus which concerns on 2nd Embodiment of this invention. It is a flowchart explaining the detailed flow at the time of photography which concerns on the 2nd Embodiment of this invention. It is a figure which shows the schematic optical composition of the SLO apparatus which concerns on 3rd Embodiment of this invention. It is a figure explaining the screen which is displayed on the display part which concerns on 3rd Embodiment of this invention. It is a flowchart explaining the detailed flow at the time of fluorescence photographing which concerns on 3rd Embodiment of this invention. It is a figure which shows the focus lens drive at the time of fluorescence photographing which concerns on 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the present invention relating to the scope of claims, and not all combinations of features described in the present embodiments are essential for the means for solving the present invention. .. Further, through the following description, it is shown that the configurations to which the same reference numbers are added in different embodiments are the same configurations.

(First Embodiment)
The first embodiment of the present invention will be described with reference to FIGS. 1 to 9. FIG. 1 shows a schematic optical configuration of the SLO apparatus according to the first embodiment of the present invention. In FIG. 1, the SLO device has an SLO light source 100 that emits shooting light and a projected optical path 10 for irradiating the eye E to be examined, and the reflected light from the fundus Er has a part of the projected optical path 10. It is incident on the light receiving unit 30 via the light receiving unit 30. Further, it has an anterior eye portion observation unit 50 for alignment of the device and a fixative lamp unit 40 for stabilizing the fixation of the eye to be inspected.

<SLO light source>
The SLO light source 100 can output light having a blue / green / red wavelength band used for color photography and light having a near infrared wavelength band used for alignment. A near-infrared light source 101IR that outputs light in the near-infrared wavelength band, a red light source 101R that outputs light in the red wavelength band, a green light source 101G that outputs light in the green wavelength band, and a blue light source that outputs light in the blue wavelength band. It is equipped with 101B. Each light source is provided with a collimator lens and is provided with a wavelength branch mirror for merging the optical path in order to output the light from each light source from the emission end 11. The collimator lens 102IR for a near-infrared light source, the collimator lens 102R for a red light source, the collimator lens 102G for a green light source, and the collimator lens 102B for a blue light source. Further, the wavelength branch mirror 103IR for a near infrared light source, the wavelength branch mirror 103R for a red light source, the wavelength branch mirror 103G for a green light source, and the wavelength branch mirror 103B for a blue light source. The wavelength-branched mirror 103IR for a near-infrared light source reflects near-infrared light, and the wavelength-branched mirror 103R for a red light source reflects red light and transmits light in other wavelength bands. Similarly, the wavelength branch mirror 103G for a green light source reflects green light and transmits other wavelength band light, and the wavelength branch mirror 103B for a blue light source reflects blue light and transmits other wavelength band light. The configuration of the light source is not limited to this, and it is sufficient that light having at least two different wavelength bands can be output. A laser diode (LD) or LED is applied to the light source. The SLO light source 100 can switch the light source to be output by the wavelength switching unit 61 of the control unit 60 shown in FIG.

<Projected optical path>
The light output from the SLO light source 100 is reflected by the branch dichroic mirror 14 with the lens 12, the lens 13, and the fixation lamp portion via the emission end 11, and passes through the hole portion of the perforated mirror 15. Then, it passes through the focus lens 16, the scanning unit 20, the lens 19, the reflection mirror 22, the branched dichroic mirror 23 with the anterior eye observation unit, and the objective lens 25, and reaches the fundus Er of the eye E to be inspected. The focus lens 16 is driven by a motor (not shown) in the optical axis direction via the control unit 60. In the scanning unit 20, X scanners 17 and Y scanners 18 that are orthogonal to each other are arranged adjacent to each other in the optical axis direction. The X-scanner 17 and the Y-scanner 18 are driven by a motor (not shown) via a control unit 60, and two-dimensionally scan the photographing light with the eye to be inspected Er. Galvano mirrors, resonance mirrors, polygon mirrors, etc. are applied to the scanner.

<Received optical path>
The photographed light reflected by the fundus Er passes through the projected optical path when it is incident on the fundus. The reflected shooting light is reflected from the fundus Er through the objective lens 25, the dichroic mirror 23, the reflection mirror 22, the lens 19, the scanning unit 20, and the focus lens 16, and is reflected by the hole peripheral mirror portion of the perforated mirror 15. Reach 30. The light receiving unit 30 is arranged with a lens 31, a lens 32, a diaphragm 33, a wavelength cut filter 34, and a light receiving element 35. As the light receiving element 35, an APD (Avalanche PhotoDeode), a PMT (Photomultiplier Tube), an MPPC (Multi-PixelPrintonCounter), or the like is applied. The light intensity signal output from the light receiving element 35 is converted into a digital signal in real time by an A / D converter (not shown), and then input to the image generation unit 63. The image generation unit 63 generates a fundus image of the fundus Ef from the input digital signal. The wavelength cut filter 34 can be replaced with the wavelength cut filter 36 via a control unit 60 by a motor (not shown), and has a characteristic of blocking light having different wavelengths.

<Fixation light section>
The fixative light unit 40 passes through the branch dichroic mirror 14 with the light source unit 100 via the fixative light source 43, the pinhole 42, and the lens 41, passes through the projected optical path, and reaches the fundus Er of the eye E to be inspected. Project a fixative light. The fixative light source 43 has a wavelength band similar to that of the green light source 101G.

<Foreground observation unit>
The anterior eye observation unit 50 illuminates the anterior eye portion of the eye E to be inspected by a light source for anterior eye observation (not shown), and the reflected light from the anterior eye portion is a branch dichroic mirror to the SLO scanning unit via the objective lens 25. It passes through 23 and forms an image on the image pickup surface of the two-dimensional image pickup element 52 via the lens 51.

<Control unit>
A control unit that controls the apparatus having the configuration shown in FIG. 1 will be described with reference to FIG.

The control unit 60 includes a wavelength switching unit 61, an optical scanning control unit 62, an image generation unit 63, a composition processing unit 64, a display control unit 65, and a focus control unit 66. Further, the control unit 60 is connected to an SLO light source 100, a focus lens 16, a scanning unit 20, a light receiving unit 30, a fixative lamp unit 40, an anterior eye observation unit 50, a wavelength cut filter 34/36, and the like. Further, a display unit 70 for displaying the shooting result, a memory 80, a stage 112, and the like are connected.

<Appearance of device>
FIG. 3 shows the appearance of the apparatus having the configuration shown in FIG. The entire optical system configuration shown in FIG. 1 is mounted on the optical head 110. The optical head 110 is mounted on a stage 112 that is driven in the depth Z direction, the horizontal X direction, and the vertical Y direction with respect to the eye E to be inspected. The stage 112 is operated by using the main body operation unit 116. At the time of shooting, the operator fixes the subject with the chin and forehead with the face receiver 114, and prompts the subject to fix the position of the eyes. The stage 112 adjusts the distance (working distance) in the Z direction between the optical head 110 and the eye E to be inspected and the alignment of the optical head 110 in the horizontal X and vertical Y directions with respect to the eye E to be inspected. The stage 112 may be controlled by an electric stage.

<Display unit>
The display unit of the apparatus having the configuration shown in FIG. 1 will be described with reference to FIG.

The display unit 70 has a region 72 for displaying the front eye portion image, a region 73 for displaying the fundus image by SLO, a mark 74 indicating the display position of the fixative, and a frame 75 indicating a shooting angle of view region. It also has a pull-down 71 for selecting a shooting mode, an adjustment bar 76 for adjusting the position of the focus lens 16, and a button 77 for instructing start and stop of shooting and shooting. Further, a focus automatic adjustment button 78 for automatically adjusting the focus 16 is provided.

<Shooting sequence>
A method of taking a color image of the fundus Er in color using the apparatus having the configuration shown in FIG. 1 will be described with reference to the flowchart of FIG. In color photography, the near-infrared light source 101IR of the light source 100 is used for alignment before photography, and at the same time as the start of photography, the red light source 101R, the blue light source 101B, and the green light source 101G are turned on in order for photography.

In step S100 of FIG. 5, when the color photographing mode is selected by the operator from the photographing mode selection pull-down shown in FIG. 4, the control unit 60 inserts the wavelength cut filter 34 into the optical path of the light receiving unit 30. Here, the wavelength cut filter 34 has a characteristic of blocking the wavelength of the green light source 101G and transmitting other light. Since the fixative light source 43 has a wavelength band similar to that of the green light source 101G, it has a role of blocking unnecessary light from the fixative from entering the fundus observation image.

In step S101, an anterior eye portion image of the eye E to be inspected is generated and displayed in the anterior eye portion display area 72. In step S102, the operator uses the SLO via the operation unit 116 so that the pupil of the anterior eye portion of the eye to be inspected is displayed in the center of the anterior eye portion display area 72 and the contrast of the iris pattern is the highest. Adjust the XYZ direction of the device. As a result, the distance (working distance) between the pupil of the eye E to be inspected and the objective lens 25 is kept constant. The operator can confirm the optical axis eccentricity of the SLO device by the front eye portion display area 72.

In step S103, after the operator presses the start button 77, the optometry light source 43 is turned on by the wavelength switching unit 61, the alignment light source 101IR is turned on, and the scanning unit 20 is driven via the optical scanning control unit 62. Then, the scanning of the measurement light to the eye to be inspected is started. An image of the fundus for alignment of the eye E to be inspected (hereinafter, referred to as a fundus observation image) is generated and displayed in the SLO fundus image region 73. At this time, the other light sources 101R, 101B, and 101G of the light source 100 are turned off.

When the operator instructs to change the size and position of the shooting angle of view region 75 while checking the fundus observation image displayed in the region 73, the control unit 60 sets the shooting range in step S104. The optical scanning control unit 62 controls the driving range of the scanning unit 20 according to the set shooting range. The drive range is stored in the memory 80 via the control unit 60. Further, the operator moves the mark 74 of the fixative so that the part to be photographed is included in the shooting angle of view while checking the fundus observation image displayed in the area 73, and in step S105, via the control unit 60. And adjust the display position of the fixative.

In step S106, the position of the focus lens 16 is adjusted based on the area 73 in which the fundus observation image is displayed. When the operator presses the focus automatic adjustment button 76 of the display unit 70, the focus lens 16 is driven via the control unit 60. Based on the brightness information of the region 73 where the fundus observation image is displayed, the focus control unit 66 moves the focus lens 16 to the position where the brightness of the fundus observation image is highest via the image generation unit 63. At this time, the operator may adjust the position of the focus lens 16 by using the focus adjustment bar 76 so as to obtain an image of a desired image quality while looking at the area 73 in which the fundus observation image is displayed.

In step S107, the fundus image is photographed by inputting the photographing button 77 of the display unit 70. The position of the focus lens 16 at the time when the shooting button 77 is pressed is recorded in the memory 80 via the control unit 60. The details of the acquisition flow of the fundus photographed image will be described later. The fundus image captured by this is stored in the memory 80 via the control unit 60.

In step S108, the fundus photographed image taken in step S107 is displayed. The captured fundus image may be displayed in the fundus image display area 73, or a display area for the photographed fundus image may be provided separately from the fundus image display area 73.

In the present embodiment, the fixation lamp has a wavelength band similar to that of the green light source 101G, but the light is not limited to this, and if the light is in the visible region that can be recognized by humans, the red light source 101R or the blue light source 101B is used. It may be in the same wavelength band. In this case, the wavelength cut filter 34 inserted in step S100 has a characteristic of blocking the light source wavelength of the fixative light source.

<Fundus image shooting flow>
Next, the details of the shooting flow of the fundus image in step S107 will be described with reference to the flowchart of FIG. 6 and the schematic diagram of the focus lens drive of FIG.

The control unit 60 detects that the shooting button 77 has been pressed and starts shooting.

In step S201, switching between the wavelength cut filter 34 and the wavelength cut filter 36 is performed via the control unit 60. The wavelength cut filter 36 has a characteristic of blocking light outside the photographing light source band. In step S202, the light source 43 of the fixative lamp is turned off via the control unit 60. In addition, steps S201 and S202 may be performed in parallel.

Hereinafter, the flow of acquiring a fundus photographed image for one frame with the red light source 101R is shown in steps S203 to S205. Further, the flow of acquiring one frame of fundus image taken by the blue light source 101B is shown in steps S206 to S208, and the flow of acquiring one frame of fundus photograph image by the green light source 101G is shown in steps S209 to S211.

In step S203, the red light source 101R is turned on via the wavelength switching unit 61. At this time, the other light sources in the light source 100, including the light source 101IR used for alignment, are turned off. Shooting the focus lens 16 in step S204 Red light offset from the position of the focus lens 16 determined at the time of adjusting the fundus observation image in step S106, that is, the position of the focus lens 16 when the shooting button 77 stored in the memory 80 is pressed. Offset by the value. In step S205, the shooting light is scanned with the shooting angle of view set in shooting step S104, and the light intensity signal received from the light receiving element 35 is input to the image generation unit 63 of the control unit 60 to acquire a signal for one frame. do. When scanning for one frame is completed, the red light source 101R is turned off.

In step S206, the blue light source 101B is turned on via the wavelength switching unit 61. At this time, the other light sources in the light source 100 are turned off. In step S207, the focus lens 16 is offset from the position of the focus lens 16 at the time of displaying the stored fundus observation image based on the focus table shown in Table 1. Specifically, the position ΔR (Z (F1)) of the focus lens 16 when shooting with a red light source is offset by ΔB (Z (F1)) −ΔR (Z (F1)) to the position of the focus lens when shooting with a blue light source. ..

In step S208, the shooting light is scanned with the shooting angle of view set in shooting step S104, and a signal for one frame is acquired. When scanning for one frame is completed, the blue light source 101B is turned off.

In step S209, the green light source 101G is turned on via the wavelength switching unit 61. At this time, the other light sources in the light source 100 are turned off. In step S210, the focus lens 16 is offset from the position of the focus lens 16 at the time of displaying the stored fundus observation image based on the focus table shown in Table 1, as in the case of the blue light source. Specifically, the position ΔB (Z (F1)) of the focus lens 16 at the time of shooting with a blue light source is offset by ΔG (Z (F1)) −ΔB (Z (F1)) from the position of the focus lens at the time of shooting with a blue light source. .. In step S211 the shooting light is scanned with the shooting angle of view set in the shooting step S104, and a signal for one frame is acquired. When scanning for one frame is completed, the green light source 101G is turned off.

By performing the operations of steps S203 to S211 described above, the control unit 60 acquires a fundus photographed image with the red light source light, the blue light source light, and the green light source light for one frame at the same scanning position. When performing superposition shooting, the above-mentioned steps S203 to S211 are repeated a predetermined number of times.

In step S212, it is determined whether or not the captured images can be acquired by a predetermined number of frames. When the control unit 60 determines that the captured images of each light source light can be acquired by a predetermined number of frames, the control unit 60 ends the imaging. The number of frames to be photographed at this time may be set in advance by input of an examiner before photographing, or may be determined from an image quality evaluation index such as contrast as a result of processing the photographed image. When the photographing is completed, the fundus photographed images of the red light source light, the blue light source light, and the green light source light are combined from the image generation unit 63 via the composition processing unit 64 to generate a pseudo-color fundus image.

FIG. 7 shows the relationship between the focus lens position determined in the shooting step S106 in the alignment light source 101IR and the position of the focus lens in each shooting light source. As for the offset amount, as shown in FIG. 7 (a), assuming that the position determined in step S106 is Z (F1), the focus lens 16 at the time of photographing the red light source 101R is as shown in FIG. 7 (b). , ΔR (Z (F1)), the position is shifted from Z (F1) in the optical axis direction. Similarly, when shooting with the green light source 101G, as shown in FIG. 7C, the position is shifted from Z (F1) by ΔG (Z (F1)) in the optical axis direction. When shooting with the blue light source 101B, as shown in FIG. 7D, the position is shifted from Z (F1) by ΔB (Z (F1)) in the optical axis direction. Further, for example, when the position determined in step S106 is Z (F5), the focus lens 16 when photographing the red light source 101R is oriented in the optical axis direction from Z (F5) by ΔR (Z (F5)). It will be the shifted position. That is, the shift amount of the focus lens of each shooting light source may be different depending on the focus lens position determined in the shooting step S106. The shift amount is stored in the memory 80 in advance according to the device, and is controlled via the focus control unit 66.

The shift amount of the focus lens stored in the memory 80 can be obtained in advance from the design value or can be obtained by calibration. When obtaining by calibration, for example, a model eye imitating the eye to be inspected is prepared and attached to the device. The model eye may have a reflective surface on the fundus surface common to each light source, assuming the surface layer of the retina, or the fundus surface may be set according to the light source wavelength in consideration of absorption and fluorescence in the fundus of the eye to be inspected. good. For example, in the case of red light source light, reflection from the choroid may be assumed, and in the case of green light source, reflection from each layer of the retina may be assumed, and a fundus reflection surface having each layer thickness may be set.

A case where the shift amount of the focus lens is obtained from calibration will be described. The alignment light source 101IR is turned on, and the focus lens 16 is moved to a position where the brightness of the model fundus image is highest, as in the photographing step S106. The position of the focus lens 16 at this time is Z (F1). Next, the alignment light source 101IR is turned off and the red light source 101R is turned on. The focus lens 16 is moved to a position where the brightness of the model eye fundus image is highest, and the amount of movement from Z (F1) is stored in the memory 80 as ΔR (Z (F1)). Next, the red light source 101R is turned off and the green light source 101G is turned on. The focus lens 16 is moved to the position where the brightness of the model eye fundus image is highest, and the value obtained by adding the amount of movement from ΔR (Z (F1)) and ΔR (Z (F1)) is calculated as ΔG (Z (F1)). ) To be stored in the memory 80. Further, the green light source 101G is turned off and the blue light source 101B is turned on. The focus lens 16 is moved to the position where the brightness of the model eye fundus image is highest, and the value obtained by adding the amount of movement from ΔG (Z (F1)) and ΔG (Z (F1)) is calculated as ΔG (Z (F1)). ) To be stored in the memory 80.

The focus lens position Z (F1) determined by the alignment light source 101IR differs in the optical axis direction depending on the diopter of the eye to be inspected. A model eye imitating the eye to be inspected is prepared according to the diopter, and the shift amounts ΔR (Z (F1)), ΔG (Z (F1)), and ΔB (Z (F1)) of each light source are determined by the method described above. You may. Further, with respect to the maximum and minimum values and the median of the diopters, the shift amount of each light source may be determined by the method described above, and the other values within the diopter range may be obtained by an approximate expression.

As described above, by changing the focus lens position depending on the photographing light source, it is possible to correct the axial chromatic aberration due to the wavelength band of each light source.

The order in which the photographing light sources are turned on is not limited to the order of the red light source, the blue light source, and the green light source described above, and may be any order. For example, FIG. 8 shows a case where a red light source, a green light source, and a blue light source are photographed in this order. The red light source is turned on in step S303, and the focus lens 16 is offset to the position stored in the memory 80 in step S304. In step S405, the shooting light is scanned for one frame at the shooting angle of view set in shooting step S104. When scanning for one frame is completed, the red light source 101R is turned off. Next, in step S306, the green light source 101G is turned on via the wavelength switching unit 61. At this time, the other light sources in the light source 100 are turned off. In step S307, the focus lens 16 is offset from the position of the focus lens 16 at the time of displaying the stored fundus observation image based on the focus table shown in Table 2. Specifically, the position ΔR (Z (F1)) of the focus lens 16 when shooting with a red light source is offset by ΔG (Z (F1)) −ΔR (Z (F1)) from the position of the focus lens when shooting with a green light source. ..

In step S308, the shooting light is scanned with the shooting angle of view set in shooting step S104, and a signal for one frame is acquired. When scanning for one frame is completed, the green light source 101B is turned off. Similarly, steps S309 to S311 are performed for the blue light source. In step S312, it is determined whether or not the captured images have been acquired for a predetermined number of frames, and the imaging is terminated.

The offset amount of the focus lens 16 related to steps S304, S307, and S310 is a difference from the focus lens position of the light source in front of the light source to be lit. Since the offset amount is often proportional to the wavelength, the offset amount of the focus lens 16 in each color light source is set in the shooting order of shifting from the long wavelength side to the short wavelength side with reference to the near-infrared light source for alignment. It becomes the minimum.

The lighting of each light source and the focus offset may be performed in parallel, or the order may be reversed. For example, the focus offset in step S204 may be performed before the lighting of the red light source in step S203. Further, regarding the focus lens 16, a single lens may be moved in the optical axis direction, or a variable focus lens may be used.

Further, when shooting with a single wavelength, the light source required by the user in advance may be set to be selected from the light source 100.

Further, in the above-mentioned example, when the fundus observation image is generated in the photographing step S103, the alignment light source 101IR is used, but the present invention is not limited to this, and an imaging light source may be used. For example, when the red light source light is used for alignment, the position adjustment of the focus lens 16 performed in the photographing step S106 is the position of the position ΔR (Z (F1)) shown in FIG. 7 (b). As shown in Table 3, the focus offset amount at the time of shooting with each light source of the red light source, the blue light source, and the green light source is the difference from the focus lens position of the red light source.

Further, in the above-mentioned example, each color light source is scanned for each frame, but a predetermined frame may be scanned for shooting. FIG. 9 shows a case where a predetermined frame is scanned and photographed. After turning on the red light source in step S403, the focus lens 16 is offset to the position stored in the memory 80 in step S404. In step S405, the shooting light is scanned for a predetermined frame at the shooting angle of view set in shooting step S104. When it is determined in step S406 that the captured images have been acquired for a predetermined number of frames, the red light source 101R is turned off and the next light source is photographed. Do the same for the green light source and the blue light source, and finish the shooting. In this case, the focus lens offset may be executed once for each color light source, and the focus drive amount can be minimized.

(Variation example of the first embodiment)
Further, when shooting at a wide angle of view, the focus position may differ for each angle of view due to not only the influence of axial chromatic aberration but also the influence of curvature of field. In this case, the focus shift amount of each shooting light source may be determined according to the value of the shooting angle of view determined in step S104. FIG. 10 shows the focus drive during wide angle of view shooting, and Table 4 shows the focus table during wide angle of view shooting.

The focus lens position determined in the shooting step S106 in the alignment light source 101IR is a function of the shooting angle of view A (X, Y). FIG. 11 shows a schematic view of the shooting angle of view of the fundus. When the shooting angle of view 1 is set in step S104, the focus lens position determined in shooting step S106 is Z (F1, A (X1, Y1)) as shown in FIG. 10A. The focus lens position of the red light source 101R is ΔR (Z (F1, A (X1, Y1))), the focus lens position of the green light source 101G is ΔG (Z (F1, A (X1, Y1))), and the blue light source 101B. The focus lens position is ΔB (Z (F1, A (X1, Y1))), and the shifted position. Table 4 shows the amount of focus offset of each light source. The shift amount is stored in the memory 80 in advance according to the device, and is controlled via the focus control unit 66.

The focus shift amount at each light source for each angle of view can be obtained in advance from the design value or can be obtained by calibration, as in the case of the shift amount shown in FIG. 7. For example, in the case of calibration, the alignment light source 101IR is turned on and the shooting angle of view 1 is set. Then, the focus lens 16 is moved to a position in the angle of view 1 where the brightness of the model fundus image is highest, and the position of the focus lens 16 at this time is Z (F1, A (X1, Y1)). Next, the alignment light source 101IR is turned off and the red light source 101R is turned on. The focus lens 16 is moved to the position where the brightness of the model fundus image in the angle of view 1 is highest, and the amount of movement from Z (F1, A (X1, Y1)) is set to ΔR (Z (F1, A (X1, X1,)). As Y1))), it is stored in the memory 80. Similarly, the shift amounts of the blue light source and the green light source are also determined. For the model fundus image, the entire range of the angle of view 1 may be used, or the position near the angle of view 1, for example, the position where the brightness is highest only in the region from the angle of view 3 to the angle of view 1 is the position of the focus lens 16. It may be determined as a position. The shift amount can be determined for each angle of view that can be set within the range in which shooting is possible, or may be obtained from an approximate expression using the maximum and minimum angle of view and the shift amount at the angle of view with the highest shooting frequency.

Further, the focus lens position may be changed even within the shooting angle of view for shooting. When the angle of view 1 shooting angle of view A (X1, Y1) is specified in the shooting flow step S104, it indicates that the angle of view 3A (X3, Y3) is within the shooting angle of view. The focus lens offset amount at each light source at this time is shown in the column of the angle of view 3 in Table 4. This focus offset is performed during one frame scanning such as step S205 in the shooting detail flow. That is, when the scanning unit 20 is at the scanning position of the angle of view 3 via the optical scanning control unit 62, for example, when shooting with a red light source, the focus lens 16 is set by the near-infrared light source for alignment in step S106. It is at a position shifted by ΔR (Z (F1, A (X3, Y3)) from the focus lens position Z (F1, A (X1, Y1)) determined in step 1, and when it is at the scanning position at the angle of view 1. , ΔR (Z (F1, A (X1, Y1)) shifted position. The same applies to other photographing light sources.

(Second embodiment)
In the first embodiment, when shooting with the shooting light of each color, the fixative lamp is turned off in order to prevent the influence of the shooting light on the light receiving portion. In the second embodiment, a configuration in which the fixative lamp is turned on even during shooting will be described in order to stabilize the fixative during shooting.

FIG. 12 shows a schematic optical configuration of the SLO apparatus of the second embodiment. Since the configuration of the first embodiment of FIG. 1 and the arrangement of the fixative lamp unit 40 are different and the other configurations are almost the same, the description of the same configuration will be omitted. Specifically, the configuration of FIG. 1 is different from the fixative light source 43A, the fixative focus lens 16A, and the pinhole 33A. That is, the fixation light source 43A has a wavelength band similar to that of the green light source 101G (hereinafter referred to as green fixation light) and light having a wavelength band similar to that of the blue light source 101B (hereinafter referred to as blue fixation). The difference is that it can be switched between (called light) and emitted. Further, the fixative focus lens 16A and the pinhole 33A, which can move in the optical axis direction in conjunction with each other, are fixed vision branched from a common projection optical path in order to prevent the fixation light from being blurred due to the offset of the focus lens 16. The difference is that they are located in the light path.

Since the shooting sequence is the same as in FIG. 5 and the detailed flow of step S107 in FIG. 5 is different, the shooting flow of the second embodiment will be described in detail using the flowchart shown in FIG.

First, in step S601, the control unit 60 inserts the wavelength cut filter 34 in front of the light receiving element 35. The wavelength cut filter 34 has a characteristic of blocking light having a wavelength band similar to that of the green fixative light of the fixative light source 43A and allowing other light to pass through. Next, in step S602, the control unit 60 turns on the green fixative light to fix the eye to be examined.

In step S603, the wavelength switching unit 61 turns on the red light source 101R. At this time, the other light sources in the light source 100 are turned off. In step S604, the focus lens 16 is offset from the position of the focus lens stored in the memory 80. Further, in order to correct the deviation of the focal position of the green fixative light by this offset, the focus lens 16A for the fixative and the pinhole 33A are interlocked, and it is obtained from the offset relationship between the red light source and the green light source. Offset according to the value (hereinafter referred to as reverse offset). This prevents the green fixative light from blurring to the subject.

In step S605, the shooting angle of view is scanned with the shooting light, and a signal for one frame is acquired. When scanning for one frame is completed, the red light source 101R is turned off.

In step S606, the wavelength switching unit 61 turns on the blue light source 101B. At this time, the wavelength cut filter 34 is still inserted, and the green fixative light is still lit. In step S607, the control unit 60 offsets the focus position of the focus lens from the focus position of the red light source shooting to the focus position of the blue light source shooting. Further, in order to correct the deviation of the focal position of the green fixative light by this offset, the focus lens 16A for the fixative and the pinhole 33A are interlocked, and it is obtained from the offset relationship between the blue light source and the green light source. Reverse offset according to the value. In step S607, the shooting angle of view is scanned with the shooting light, and a signal for one frame is acquired. When scanning for one frame is completed, the blue light source 101B is turned off.

In step S609, the wavelength switching unit 61 switches from the green fixative light to the blue fixative light and switches the wavelength cut filter 34 to 36. The wavelength cut filter 36 has a characteristic of blocking blue fixative light and allowing other light to pass through. In step S610, the wavelength switching unit 61 turns on the green light source 101G. At this time, the other light sources in the light source 100 are turned off. In step S611, the control unit 60 offsets the focus position of the focus lens from the focus position of the blue light source shooting to the focus position of the green light source shooting. Further, in order to correct the deviation of the focal position of the blue fixative light by this offset, the focus lens 16A for the fixative and the pinhole 33A are interlocked, and it is obtained from the offset relationship between the green light source and the blue light source. Reverse offset according to the value. In step S612, the shooting angle of view is scanned with the shooting light, and a signal for one frame is acquired. When scanning for one frame is completed, the green light source 101G is turned off.

By repeating the operations of steps S601 to S612 described above, it is possible to acquire a plurality of frame images of each color having high image quality in which the axial chromatic aberration of each light source is corrected. At that time, since the blur of the fixative lamp due to the difference in the focus position is prevented, an image with higher image quality can be acquired.

(Third embodiment)
The third embodiment shows a configuration suitable for photographing based on the fluorescence emitted by the fluorescent substance of the fundus. That is, the wavelengths of the photographing light and the received light are different, and the focus on the light receiving element is changed between the time of photographing and the time of receiving light. For example, in order to photograph the distribution of lipofuscin on the retinal pigment epithelium, the case where the fundus is irradiated with blue light and then excited to generate red fluorescence is shown below.

<Device configuration>
A schematic diagram of the third embodiment is shown in FIG. The basic configuration is the same as that of the first embodiment shown in FIG. The light emitted from the light source 100 passes through the projected optical path 10 and is applied to the fundus Er of the eye E to be inspected through the objective lens 25. The light reflected from the eye to be inspected Er passes through an optical path common to the projected optical path, is reflected by the perforated mirror 15, and is incident on the light receiving unit 30. The photographing light incident on the light receiving unit 30 passes through the focus lens 37 for fluorescence photography having a motor (not shown) that can be driven in the optical axis direction through the lens 31, and passes to the aperture 33, the wavelength cut filter 34, and the light receiving element 35. To reach.

<Fluorescence photography sequence>
A method of fluorescently photographing the fundus Er in the fundus using the apparatus having the configuration shown in FIG. 14 will be described. In the fluorescence imaging, the near-infrared light source 101IR of the light source 100 is used for the alignment of the photographing eye, the blue light source 101B is turned on at the same time as the imaging is started, and the red fluorescent light mainly from the fundus is received for imaging.

In step S100 of FIG. 5, the fluorescence imaging mode is selected from the imaging mode selection pull-down shown in FIG. The operation after the fluorescence imaging mode is selected is the same as that of FIG. 5 imaging flow of the first embodiment.

The details of the acquisition flow of the fundus image in step S107 will be described with reference to the flowchart of FIG. 16 and the schematic diagram of the focus lens drive at the time of fluorescence imaging of FIG.

In step S501 of FIG. 16, switching between the wavelength cut filter 34 and the wavelength cut filter 38 is performed via the control unit 60. The wavelength cut filter 38 has a characteristic of blocking light outside the red light band of the fluorescent wavelength to be received.

In step S503, the blue light source 101B is turned on via the wavelength switching unit 61. At this time, the other light sources in the light source 100 are turned off. The focus lens 16 is offset from the position of the focus lens 16 determined at the time of adjusting the fundus observation image in the photographing step S106 in step S504. Further, in step S505, the focus lens 37 for fluorescence photographing is offset according to the fluorescence wavelength. FIG. 17 shows a diagram relating to the positions of the focus lens 16 and the fluorescent focus lens 37 during fluorescence photography at the time of photography. As shown in FIG. 17A, assuming that the position of the focus lens 16 at the time of adjusting the fundus observation image is Z (F1), the position of the focus lens 16 at the time of fluorescence imaging is shifted by ΔB (Z (F1)). become. Here, the focus lens 37 at the time of adjusting the fundus observation image is at the initial position Z (K1) adjusted to the near-infrared light for alignment (light source 101IR). As shown in FIG. 17B, the focus lens 37 for fluorescence at the time of photographing is a position shifted from the initial position Z (K1) by ΔBR (Z (K1)). Table 5 shows the relationship between the focus lens positions described above. At the same time as offsetting the position of the focus lens for fluorescence, the diameter of the aperture 33 may be changed according to the fluorescence wavelength.

In step S506, the shooting light is scanned with the shooting angle of view set in the shooting step S104, and the light intensity signal received from the light receiving element 35 is input to the control unit 60 to acquire a signal for one frame. When scanning for one frame is completed, the blue light source 101B is turned off. In step S307, it is determined whether or not the captured images have been acquired by a predetermined number of frames, and the imaging is terminated. When the imaging is completed, the image generation unit 63 generates a fluorescent fundus image.

Although the configuration of irradiating a blue light source and receiving red fluorescent light has been described, the configuration is not limited to this, and a configuration of irradiating with another wavelength, for example, red light and receiving near infrared fluorescent light may be used. Further, as shown in the first embodiment, the focus offset amount may be a function of the shooting angle of view.

Although the present invention has been described above with the embodiments, the above embodiments are merely examples of embodiment of the present invention, and the technical scope of the present invention is limitedly interpreted by these. It shouldn't be. That is, the present invention can be implemented in various forms without departing from the technical idea or its main features.

[Other embodiments]
Although the embodiments have been described in detail above, the disclosed technology can be implemented as, for example, a system, an apparatus, a method, a program, a recording medium (storage medium), or the like. Specifically, it may be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, an image pickup device, a web application, etc.), or may be applied to a device consisting of one device. good.

Needless to say, the object of the present invention is achieved by doing the following. That is, a recording medium (or storage medium) in which a program code (computer program) of software that realizes the functions of the above-described embodiment is recorded is supplied to the system or device. Needless to say, the storage medium is a computer-readable storage medium. Then, the computer (or CPU or MPU) of the system or device reads and executes the program code stored in the recording medium. In this case, the program code itself read from the recording medium realizes the function of the above-described embodiment, and the recording medium on which the program code is recorded constitutes the present invention.

16 Focus lens 20 Scanning unit 25 Objective lens 30 Light receiving unit 34 Wavelength cut filter 40 Fixative light unit 50 Front eye observation unit 60 Control unit 70 Display unit 80 Memory 100 SLO light source 110 Optical head 112 Stage

Claims (10)

An irradiation means that irradiates the eye to be inspected with the photographing light emitted from the light source via the focus means, and
A light receiving unit that receives the return light of the photographing light from the eye to be inspected, and a light receiving portion.
A generation means for generating an image of the fundus of the eye to be inspected based on the received return light.
It has a control means for adjusting the focus means and controlling the light source.
The control means controls so that the photographing light having the first wavelength is emitted from the light source, and the photographing light having the first wavelength is focused on a predetermined position in the depth direction of the fundus. Adjust the focus means,
The focus is changed so that the shooting light of the first wavelength emitted from the light source is changed to the shooting light of the second wavelength, and the shooting light of the second wavelength is focused on the predetermined position of the fundus. Adjust the means,
The generation means is characterized in that an image of the first fundus due to the return light of the photographing light having the first wavelength and an image of the second fundus caused by the return light of the photographing light having the second wavelength are generated. Fundus photography device. The fundus photography apparatus according to claim 1, wherein the light source emits photographing light having three wavelengths of red (R), green (G), and blue (B). The fundus photography apparatus according to claim 1 or 2, wherein the adjustment of the focusing means is a movement of the focusing means in the optical axis direction of the photographing light. Further, it has a storage means for storing information for correcting the shift amount of the focus position due to the difference in the wavelength of the shooting light.
The fundus photography apparatus according to any one of claims 1 to 3, wherein the control means adjusts the focus means based on the information stored in the storage means. The light source further emits shooting light having a wavelength of near-infrared light used for alignment.
The information stored in the storage means is the information based on the difference between the position where the photographing light having the wavelength of the near infrared light is focused and the position where the photographing light having each wavelength is focused, according to claim 4. Fundus photography device. A scanning means that switches the shooting angle of view by changing the drive range,
Further having a storage means for storing information for correcting the shift amount of the focus position of the shooting light due to the difference in the shooting angle of view.
The fundus photography apparatus according to any one of claims 1 to 3, wherein the control means adjusts the focus means based on the information stored in the storage means. Control means to control shooting,
A means for switching between a color photography mode for photographing the fundus reflection of the eye to be inspected and a fluorescence photography mode for photographing the fluorescence from the eye to be inspected.
Further, in the fluorescence photographing mode, a second focusing means for focusing on a light receiving portion in which the photographed light receives the return light reflected by the fundus is provided.
The fundus photography apparatus according to claim 1, wherein the control means adjusts the second focusing means so that the photographing light is focused on a predetermined position in the depth direction of the light receiving portion. Further having a storage means for storing information for correcting the shift amount of the focus position due to the difference in wavelength between the photographing light and the fluorescent light.
The fundus photography apparatus according to claim 7, wherein the control means adjusts the second focus means based on the information stored in the storage means. A fixative lamp with a wavelength different from the wavelength of the shooting light,
The fundus photography apparatus according to any one of claims 1 to 8, further comprising a third focusing means for correcting a shift in focus of the fixative lamp due to a change in the photographing light. An irradiation means that irradiates the eye to be inspected with the photographing light emitted from the light source via the focus means, and
A light receiving unit that receives the return light of the photographing light from the eye to be inspected, and a light receiving portion.
A generation means for generating an image of the fundus of the eye to be inspected based on the received return light.
It is a control method of a fundus photography apparatus having the adjustment of the focus means and the control means of controlling the light source.
The control means controls the light source so that the light of the first wavelength is emitted, and the light of the first wavelength is focused on a predetermined position in the depth direction of the fundus. Adjust the focus means,
The focus is changed so that the shooting light of the first wavelength emitted from the light source is changed to the shooting light of the second wavelength, and the shooting light of the second wavelength is focused on the predetermined position of the fundus. Adjust the means,
It is characterized in that the generation means generates an image of the first fundus by the return light of the photographing light of the first wavelength and an image of the second fundus by the return light of the photographing light of the second wavelength. How to control the fundus photography device.

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