Ophthalmologic apparatus and control method of ophthalmologic apparatus

Abstract

To acquire an ophthalmologic image with appropriate brightness.SOLUTION: An ophthalmologic apparatus includes an imaging unit for imaging the ocular fundus of an eye to be examined using a first image pickup device and a second image pickup device with higher sensitivity than that of the first image pickup device, and a control unit for controlling light volume made incident on the imaging unit. The control unit controls light volume by a first range with first light volume as a lower limit when the imaging unit performs imaging using the first image pickup device, and controls light volume by a second range with second light volume lower than the first light volume as a lower limit when the imaging unit performs imaging using the second image pick-up device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an ophthalmic apparatus and a control method for the ophthalmic apparatus. [Background technology]

[0002] A fundus camera device for capturing fundus images of a subject's eye is known as an ophthalmic device. Because the fundus has various regions with different light reflection intensities, the fundus camera device is required to be able to capture images over a wide dynamic range. Patent Document 1 discloses an apparatus for capturing fundus images with a wide dynamic range by performing high dynamic range synthesis on multiple fundus images captured under different exposure conditions (such as the intensity of illumination light and the sensitivity of the image sensor). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-213555 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, recent fundus camera devices are required to be compatible with various imaging methods, such as flash light photography, which uses bright light, and fluorescent photography, which detects weak light. However, conventional fundus camera devices, for example, may lack a dynamic range, making it difficult to obtain fundus images with appropriate brightness.

[0005] Therefore, an object of the present disclosure is to acquire a fundus image with appropriate brightness. [Means for solving the problem]

[0006] The ophthalmic device disclosed herein is an ophthalmic device comprising an imaging unit that photographs the fundus of a subject's eye using a first imaging element and a second imaging element that is more sensitive than the first imaging element, and a control unit that controls the amount of light incident on the imaging unit, wherein the control unit controls the amount of light within a first range having a first light amount as a lower limit when the imaging unit photographs using the first imaging element, and controls the amount of light within a second range having a second light amount lower than the first light amount when the imaging unit photographs using the second imaging element. [Effects of the Invention]

[0007] According to the present disclosure, a fundus image with appropriate brightness can be acquired. [Brief explanation of the drawings]

[0008] [Figure 1] 1 shows a schematic configuration example of the device. [Figure 2] 1 shows a schematic configuration example of a control unit of the device. [Figure 3] 1 shows an example of a circuit configuration for adjusting the light source. [Figure 4] An example of a dimming configuration using an ND filter is shown below. [Figure 5] An example of the dimming range of the device is shown below. [Figure 6] 1 shows an example of a configuration for switching between image pickup elements. [Figure 7] 1 shows an example of a shooting flow in the first embodiment. [Figure 8] 10 shows an example of a shooting flow in a first modified example of the first embodiment. [Figure 9] 10 shows an example of an image display in Modification 1 of Embodiment 1. [Figure 10] 10 shows an example of a shooting flow in a second modification of the first embodiment. [Figure 11] 10 shows an example of an image display in Modification 2 of Embodiment 1. [Figure 12] 10 shows an example of the configuration of an image sensor according to the second embodiment. [Figure 13] 10 shows an example of a shooting flow in the second embodiment. [Figure 14]10 shows an example of a generated image in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, exemplary embodiments for carrying out the present disclosure will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of components described in the following embodiments are arbitrary and can be changed depending on the configuration of an apparatus to which the present disclosure is applied or various conditions. In addition, the same reference numerals are used in the drawings to indicate identical or functionally similar elements.

[0010] (Embodiment 1) The apparatus according to this embodiment is an ophthalmologic apparatus that is equipped with a low-sensitivity image sensor and a high-sensitivity image sensor, switches the image sensor depending on the shooting mode, and changes exposure control according to the switched image sensor.

[0011] <Device configuration> The present embodiment will be described below with reference to FIG. 1, which shows a schematic configuration of an ophthalmic apparatus according to the present embodiment and its optical system.

[0012] In the following description, the direction that approximately coincides with the line of sight of the subject's eye E is referred to as the Z direction. The plane perpendicular to the Z direction is referred to as the XY plane, the horizontal direction is referred to as the X direction, and the vertical direction is referred to as the Y direction.

[0013] The ophthalmic apparatus includes an imaging unit 100, a control unit 200, and a display unit 300. The display unit 300 may be a monitor provided in the ophthalmic apparatus or a monitor separate from the ophthalmic apparatus. The display unit 300 may also be an operable monitor such as a touch panel. The configurations of the imaging unit 100 and the control unit 200 will be described below in order.

[0014] <Configuration of the imaging unit 100> The imaging unit 100 is composed of a measurement optical system for capturing two-dimensional images of the anterior segment Ea of the subject's eye E and the fundus Er of the subject's eye E. Various optical systems arranged in the imaging unit 100 will be described below.

[0015] In the imaging unit 100, an objective lens 101 is installed facing the subject's eye E. A perforated mirror 131, a photographing aperture 132, a focus lens 133, an imaging lens 134, and a removable mirror 135 are arranged on the optical axis L1 of the objective lens 101. The perforated mirror 131 has an opening in the center. The focus lens 133 adjusts its focus by moving its position on the optical axis L3. The removable mirror 135 can be inserted and removed on the optical axis L1 to switch between the optical path of the optical axis L2 leading to the image sensor 136 and the optical path of the optical axis L3 leading to the image sensor 137. The image sensors 136 and 137 are fundus image sensors that are sensitive to visible light and infrared light and are capable of both video observation and still image capture. The image sensor 136 is a CCD sensor or CMOS sensor that outputs an electrical signal according to the amount of charge obtained by photoelectric conversion of incident light, and has lower sensitivity than the image sensor 137. The image sensor 137 is a SPAD (Single Photon Avalanche Diode) sensor that counts the number of photons in incident light and outputs an electrical signal according to the count value, and has higher sensitivity than the image sensor 136. Here, sensitivity refers to the magnitude of the signal output relative to the amount of light incident on the image sensor. However, a method for determining whether an image sensor has high sensitivity or low sensitivity may be determined, for example, using the brightness of a fundus image output relative to the amount of light illuminating the subject's eye as an index. Specifically, for example, an image sensor that can acquire a fundus image with appropriate brightness when the amount of light illuminating the subject's eye is approximately 3 EV may be determined as a high-sensitivity image sensor, and an image sensor that cannot acquire a fundus image with appropriate brightness may be determined as a low-sensitivity image sensor. The image sensor 137 only needs to have higher sensitivity than the image sensor 136. In addition to a SPAD sensor, the image sensor 137 may also be an ultra-high-sensitivity CCD sensor or CMOS sensor. The image sensor 136 is an example of a first image sensor. The image sensor 137 is also an example of a second image sensor.

[0016] A corneal baffle 140, a relay lens 141, a focus index unit 142, a lens 143, a ring slit 144, a lens baffle 145, and a removable ND (Neutral Density) filter 146 are arranged on an optical axis L4 in the reflection direction of the perforated mirror 131. The focus index unit 142 is movable along the optical axis L4 and is removable and insertable onto the optical axis L4. The focus index unit 142 is equipped with an infrared light source and a visible light source, and can project an index onto the fundus by switching between the emitted light sources. The corneal baffle 140 has a light-blocking point in the center. The ring slit 144 has a ring-shaped slit opening. The lens baffle 145 is a light-blocking member having a light-blocking point. The removable ND filter 146 has an adjustable amount of light transmitted and is removable and insertable onto the optical axis L4. A second dichroic mirror 147, which transmits infrared light and reflects visible light, is also arranged on the optical axis L4.

[0017] A condenser lens 148 and an observation light source 149 are arranged on an optical axis L5 in the transmission direction of the second dichroic mirror 147. The observation light source 149 is an observation light source having a plurality of infrared LEDs that emit constant infrared light. A condenser lens 150 and an imaging light source 151 are arranged in the reflection direction of the second dichroic mirror 147. The imaging light source 151 is an imaging light source having a plurality of white LEDs that emit pulses of visible light. The objective lens 101, the second dichroic mirror 147, the optical members between them, and the condenser lens 148 and 150 constitute an illumination optical system that illuminates the subject's eye E. Light from the observation light source 149 or the imaging light source 151 illuminates the subject's eye E via this illumination optical system. The illumination optical system is an example of an illumination unit that illuminates the subject's eye.

[0018] <Configuration of control unit 200> Next, the schematic configuration of the control unit 200 will be described with reference to Fig. 2. The control unit 200 includes a shooting control unit 201, an image acquisition unit 202, an exposure control unit 203, and an image generation unit 204.

[0019] The photographing control unit 201 is connected to an operation unit 310 such as a mouse or keyboard, an image acquisition unit 202, and an exposure control unit 203, and controls exposure by the exposure control unit 203 and image acquisition by the image acquisition unit 202 based on an input signal from the operation unit 310. The photographing control unit 201 is also connected to an image generation unit 204 and an image display unit 300 such as a display, and captures images generated by the image generation unit 204 and controls display on the image display unit 310. In other words, the photographing control unit 201 has a function as a display control unit that controls display of fundus images on the display unit.

[0020] The exposure control unit 203 is connected to the image acquisition unit 202, and measures the brightness of the subject's eye E based on the images acquired by the image acquisition element 136 and the image acquisition element 137, and controls the exposure so that the photographed image of the fundus E has appropriate brightness. The exposure control unit 203 controls the removable ND filter 146, the observation light source 149, and the photographing light source 151 based on the photometric value, and adjusts one or both of the amount of illumination light to the subject's eye E and the amount of reflected light from the subject's eye E. The exposure control unit 203 also adjusts the exposure time and gain of the image acquisition element 136 and the image acquisition element 137 based on the photometric value.

[0021] The image acquisition unit 202 is connected to the photography control unit 201, exposure control unit 203, removable mirror 135, image sensor 136, and image sensor 137, and inserts and removes the removable mirror 135 that switches the optical path from the subject's eye E in response to an instruction from the photography control unit 201, and acquires an image signal from the image sensor 136 or 137 under conditions instructed by the exposure control unit 203. The image acquisition unit 202 is also connected to the image generation unit 204, and transmits the acquired image data to the image generation unit 204.

[0022] The image generation unit 204 is connected to the image acquisition unit 202 and the photography control unit 201, and performs predetermined signal processing on the image signal received from the image acquisition unit 202 to generate a fundus observation image or a fundus photography image, which is then transmitted to the photography control unit 201.

[0023] <Dimming method using a light source> Next, a dimming method using the imaging light source 151 by the exposure control unit 203 will be described with reference to FIG. 3. The imaging light source 151 shown in FIG. 3(a) has multiple LEDs, such as LED 401, LED 402, LED 411, and LED 412, arranged in a ring shape. In the LED drive circuit shown in FIG. 3(b), applying a voltage V0 to the positive input terminal of an operational amplifier 403 turns on an FET 404, causing multiple LEDs connected to the drive circuit, including LED 401 and LED 402, to emit light. In addition, increasing or decreasing the voltage value of voltage V0 can increase or decrease the current flowing through the LEDs. In other words, increasing or decreasing the voltage value of voltage V0 can increase or decrease the amount of light emitted by the LEDs. In the LED drive circuit shown in FIG. 3(c), applying a voltage V1 to the positive input terminal of an operational amplifier 413 causes multiple LEDs connected to the drive circuit, including LED 411 and LED 412, to emit light.

[0024] The exposure control unit 203 applies a voltage to both V0 and V1 to light up all LEDs, including LED 401 and LED 402, on the light source 151 in Fig. 3(a). Alternatively, the exposure control unit 203 can apply a voltage to either V0 or V1 to light up either the multiple LEDs connected to the drive circuit in Fig. 3(b) or the multiple LEDs connected to the drive circuit in Fig. 3(c). In other words, the exposure control unit 203 can control the number of LEDs that emit light and adjust the amount of light emitted by independently turning on and off the application of voltage to the multiple LED drive circuits.

[0025] Here, we have shown an example in which the light output of the light source can be adjusted by controlling the current flowing through the LEDs and the number of LEDs that are turned on. However, the light output can also be adjusted by controlling the time that current flows through the LEDs and changing the light output time. Also, while we have shown an example in which there are two drive circuits, the number of drive circuits can be three or more. By increasing the number of drive circuits, the light output can be adjusted more precisely.

[0026] Here, the method for adjusting the light intensity of the imaging light source 151 has been described, but the light intensity of the illumination light source 149 can also be adjusted in the same manner.

[0027] <Light control method using an ND filter> Next, a light control method using the insertable / removable ND filter 146 by the exposure control unit 203 will be described with reference to FIG. 4. The insertable / removable ND filter 146 is an optical filter that can be inserted and removed on the optical path L4. As shown in FIG. 4(a), the amount of illumination light to the test eye E can be reduced by inserting it onto the optical path L4 as shown in FIG. 4(b) from the state of being pulled out from the optical path L4. Here, an example using an ND filter having a single optical transmittance as the optical member for reducing light is shown, but other optical members may be used. An ND filter with continuously variable optical transmittance may be used to further expand the light control range. Also, as the optical member, an aperture, a half mirror, or other optical filters may be used to reduce the light amount.

[0028] Here, the insertable / removable ND filter 146 is arranged in the illumination optical system near the light source (within the optical system between the light source and the test eye E) to reduce the amount of irradiation light to the test eye E, but it may be arranged at other positions. The insertable / removable ND filter 146 may be arranged between the objective lens 101 and the perforated mirror 131 to reduce both the amount of illumination light to the test eye E and the amount of reflected light from the test eye E. Also, the insertable / removable ND filter 146 may be arranged between the insertable / removable mirror 135 and the imaging device 137 (within the optical system between the test eye and the imaging device 137) to reduce the amount of reflected light from the test eye E.

[0029] <(Light control range by the exposure control unit 203> Next, the light control range by the exposure control unit 203 will be described with reference to FIG. 5.

[0030] FIG. 5(a) is a diagram showing the relationship between the LED current of the imaging light source 151 and the light source light intensity. When all of the multiple LEDs are turned on, the exposure control unit 203 can control the light intensity within a dimming range 503. When half of the multiple LEDs are turned on, the exposure control unit 203 can control the light intensity within a dimming range 504, which is different from the dimming range 503. Therefore, the exposure control unit 203 can control the light source within a wide dimming range 505, which is the combination of the dimming range 503 and the dimming range 504, by increasing or decreasing the number of LEDs to be illuminated in addition to controlling the current value flowing through the LEDs. Note that the dimming range 503 is an example of a first range having a first light intensity as its lower limit. Furthermore, the dimming range 505 is an example of a second range having a second light intensity as its lower limit, which is lower than the first light intensity.

[0031] FIG. 5B is a diagram showing the relationship between the light source light intensity of the imaging light source 151 and the illumination light intensity on the subject's eye E. When the removable ND filter 146 is not used to reduce light intensity, the exposure control unit 203 can adjust light intensity within a dimming range 513. When the ND filter 146 is used to reduce light intensity, the exposure control unit 203 can adjust light intensity within a dimming range 514, which is different from the dimming range 513. Therefore, by controlling the insertion and removal of the ND filter in addition to controlling light source dimming, the exposure control unit 203 can adjust the illumination light intensity within a wide dimming range 515, which is a combination of the dimming range 513 and the dimming range 514. The dimming range 513 is an example of a first range having a first light intensity as its lower limit. The dimming range 515 is an example of a second range having a second light intensity as its lower limit, which is lower than the first light intensity.

[0032] If the current flowing through the LEDs is excessively reduced in order to reduce the light intensity, the color development of the illumination light may deteriorate. Furthermore, if the number of LEDs that emit light is excessively reduced in order to reduce the light intensity, the brightness of the illumination light may become uneven. Furthermore, if the light-emission time is excessively shortened in order to reduce the light intensity, the LED light emission may become unstable. Therefore, in the exposure control of this embodiment, by using the ND filter 146 to dim the light in addition to the dimming control of the imaging light source 151, a wide dimming range is achieved, and deterioration of color development, uneven brightness, and unstable light emission are less likely to occur.

[0033] <Switching of image pickup elements by the image acquisition unit 202> Next, switching of the image capturing element will be described with reference to FIG. 6. The image capturing unit 202 switches the image capturing element to capture an image and captures an image from the image capturing element onto which reflected light from the subject's eye E is incident. When performing low-sensitivity imaging using the image capturing element 136, the image capturing unit 202 pulls out the removable mirror 135 from the optical path L1 as shown in FIG. 6(a) and causes reflected light from the subject's eye E to be incident on the image capturing element 136. The image capturing unit 202 then captures a low-sensitivity image signal from the low-sensitivity image capturing element 136. When performing high-sensitivity imaging using the image capturing element 137, the image capturing unit 202 inserts the removable mirror 135 into the optical path L1 as shown in FIG. 6(b). When the removable mirror 135 is inserted, the reflected light from the subject's eye E is reflected by the removable mirror 135, causing the reflected light from the subject's eye E to be incident on the image capturing element 137. The image capturing unit 202 then captures a high-sensitivity image signal from the high-sensitivity image capturing element 137.

[0034] <Shooting flow> The photographing flow in this embodiment will be described with reference to FIG.

[0035] In step S701, the imaging control unit 201 starts imaging in response to an operation by the examiner from the operation unit 340, and the process proceeds to step S702.

[0036] In step S702, the imaging control unit 201 selects whether to perform low-sensitivity imaging or high-sensitivity imaging. If low-sensitivity imaging is selected, the process proceeds to step S703. If high-sensitivity imaging is selected, the process proceeds to step S713. Here, the imaging control unit 201 switches between low-sensitivity imaging and high-sensitivity imaging depending on the imaging mode. For example, low-sensitivity imaging is selected when capturing a still image using a high amount of flash light or when capturing an optic disc, which has a high reflectivity. Also, high-sensitivity imaging is selected when capturing a video or fluorescent image using a low amount of light or when capturing an image of the macula, which has a low reflectivity. Alternatively, a high-sensitivity imaging mode and a low-sensitivity imaging mode may be provided, and the examiner may be able to select either the high-sensitivity imaging mode or the low-sensitivity imaging mode by operating the operation unit 340. In this case, high-sensitivity imaging can be performed, for example, even when capturing an image of the optic disc of a subject's eye, which is prone to miosis.

[0037] (Low sensitivity shooting flow) In step S703, the image acquisition unit 202 pulls out the removable mirror 135 from the optical path L1, causing the reflected light from the subject's eye E to be incident on the image sensor 136, and the process proceeds to step S704.

[0038] In step S704, the image acquisition unit 202 removes the removable ND filter 146 from the optical path L4, so that the amount of illumination light to the eye E is not reduced, and the process proceeds to step S705.

[0039] In step S705, the image acquisition unit 202 starts acquiring an image from the image sensor 136, and the process proceeds to step S706.

[0040] In step S706, the photography control unit 201 projects an infrared light index from the focus index unit 142 onto the subject's eye E, and performs focus adjustment by moving the focus lens 133 and the focus index unit 142 based on the image acquired by the image acquisition unit 202. When the photography control unit 201 completes the focus adjustment, the process proceeds to step S707.

[0041] In step S707, the exposure control unit 203 determines the exposure conditions for low-sensitivity imaging. The exposure control unit 203 adjusts the amount of light illuminating the fundus by setting the current value to be passed through the LED of the imaging light source 151 based on the image acquired by the image acquisition unit 202. Because the removable mirror 135 is retracted from the optical path L1, the amount of light illuminating the fundus is adjusted within the dimming range 513 in FIG. 5. The lower limit of the dimming range 513 is an example of a first light amount. The upper limit of the dimming range 513 is an example of a third light amount. The exposure control unit 203 also sets the gain and exposure time for imaging with the image sensor 136. When the exposure control unit 203 completes the exposure control, the process proceeds to step S708.

[0042] In step S708, the image acquisition unit 202 captures an image under the exposure conditions determined in step S707 and acquires an image signal. When the image acquisition unit 202 completes acquisition of the image signal and transmits the image signal to the image generation unit 204, the process proceeds to step S709.

[0043] In step S709, the image generation unit 204 performs brightness correction, contrast correction, gamma correction, etc. on the received image signal to generate a fundus image. After the image generation unit 204 transmits the generated image to the imaging control unit 201, the process proceeds to step S710.

[0044] (High sensitivity shooting flow) In step S713, the image acquisition unit 202 inserts the removable mirror 135 onto the optical path L1, causing reflected light from the subject's eye E to be incident on the image sensor 137, and the process proceeds to step S714.

[0045] In step S714, the image acquisition unit 202 inserts the removable ND filter 146 onto the optical path L4 to reduce the amount of illumination light onto the eye E, and the process proceeds to step S715.

[0046] In step S715, the image acquisition unit 202 starts acquiring an image from the image sensor 137, and the process proceeds to step S716.

[0047] In step S716, the imaging control unit 201 projects a visible light index from the focus index unit 142 onto the subject's eye E, and adjusts the focus by moving the focus lens 133 and the focus index unit 142 based on the image acquired by the image acquisition unit 202. In step S706 for low-sensitivity imaging, when adjusting the focus, the imaging control unit 201 projects an infrared light index with a wavelength different from that of the imaging light in order to suppress miosis of the eye. On the other hand, in step S716 for high-sensitivity imaging, because the high-sensitivity image sensor 137 is used, the imaging control unit 201 can adjust the focus by projecting a low amount of visible light that does not cause miosis of the eye, and can achieve higher accuracy in focusing than when infrared light is used. When the imaging control unit 201 completes the focus adjustment, the process proceeds to step S717.

[0048] In step S717, the exposure control unit 203 determines the exposure conditions for high-sensitivity shooting.

[0049] The exposure control unit 203 adjusts the amount of light illuminating the fundus by setting the current value to be passed through the LEDs of the imaging light source 151, the number of LEDs to be illuminated, and the time for which current is passed through the LEDs, based on the image acquired by the image acquisition unit 202. Because the removable mirror 135 is inserted into the optical path L1, the amount of light illuminating the fundus is adjusted within the dimming range 514 in FIG. 5. The lower limit of the dimming range 514 is an example of a second light amount. The upper limit of the dimming range 514 is an example of a fourth light amount. The exposure control unit 203 also sets the gain and exposure time for capturing images with the image sensor 137. When controlling exposure in step S707 for low-sensitivity capturing, the exposure control unit 203 adjusts only the current value to be passed through the LEDs of the imaging light source 149. However, in this case, the number of LEDs to be illuminated and the time for which current is passed through the LEDs are also changed, allowing adjustment over a wide dimming range. Furthermore, if an ND filter with continuously variable optical transmittance is used as the removable ND filter 146, the exposure control unit 203 adjusts the transmittance and controls light over an even wider range. Furthermore, when controlling exposure in step S707 for low-sensitivity shooting, the exposure control unit 203 adjusted the gain and exposure time for the entire image sensor. Here, however, the image capturing area of ​​the image sensor 137 is divided, and gain settings and exposure time are adjusted for each divided area. By controlling exposure for each divided area, the exposure control unit 203 reduces overexposure in highly reflective areas in high-sensitivity images. When the exposure control unit 203 completes exposure control, the process proceeds to step S718.

[0050] In step S718, the image acquisition unit 202 captures an image under the exposure conditions determined in step S717 and acquires an image signal. When the image acquisition unit 202 completes acquisition of the image signal and transmits the image signal to the image generation unit 204, the process proceeds to step S719.

[0051] In step S719, the image generation unit 204 performs brightness correction, contrast correction, gamma correction, etc. on the received image signal to generate a fundus image. Here, the image generation unit 204 performs correction using a high-sensitivity correction value different from the correction used in step S709 for low-sensitivity imaging, thereby generating an image suited to the high-sensitivity image sensor 137. For example, gamma correction and color adjustment can be performed according to the sensitivity and color filter characteristics of the image sensor of the SPAD sensor. Alternatively, a photon count map image in which the number of photons of light incident on the image sensor 137 corresponds to brightness may be output without performing correction processing. Once the image generated by the image generation unit 204 is sent to the imaging control unit 201, the process proceeds to step S710.

[0052] In step S710, the imaging control unit 201 displays the captured image on the image display unit 310, and then the imaging process ends.

[0053] As described above, in this embodiment, an ophthalmologic apparatus is described that is equipped with a low-sensitivity image sensor and a high-sensitivity image sensor, switches between the image sensors depending on the shooting mode, and changes exposure control depending on the image sensor that has been switched in. By selectively using the low-sensitivity image sensor and the high-sensitivity image sensor and performing dimming control using control of the light emission amount of the light source and control of insertion and removal of an ND filter, a wide dynamic range can be achieved, and fundus images with appropriate brightness can be acquired.

[0054] (Modification 1 of Embodiment 1) In the first embodiment, a flow for reducing the amount of illumination light to the subject's eye E using an ND filter during high-sensitivity photography has been described, but a flow for not using an ND filter (not inserting an ND filter) may also be provided. This flow is used, for example, when photographing weak fluorescence such as in fluorescence photography.

[0055] A flow in which an ND filter is not used (an ND filter is not inserted) will be described with reference to FIGS.

[0056] In step S801, the imaging control unit 201 starts imaging in response to an operation by the examiner from the operation unit 340, and the process proceeds to step S803.

[0057] In step S803, the image acquisition unit 202 inserts the removable mirror 135 onto the optical path L1, causing reflected light from the subject's eye E to be incident on the image sensor 137, and the process proceeds to step S804.

[0058] In step S804, the image acquisition unit 202 removes the removable ND filter 146 from the optical path L4, so that the amount of illumination light to the eye E is not reduced, and the process proceeds to step S805.

[0059] In steps S805 to S809, high-sensitivity fluorescent photography is performed in the same manner as in steps S715 to S719, and the process then proceeds to step S810.

[0060] In step S810, the imaging control unit 201 displays the captured image on the image display unit 310 and ends the imaging. The image display unit 310 displays a screen 900 shown in FIG. 9A. The screen 900 displays a fundus image 901 captured using fluorescence. The screen 900 also includes a display button 903 that can display a fundus image corrected by the image generation unit 204, and a display button 904 that can display a fundus photon count map that has not been corrected by the image generation unit 204. When the examiner presses the display button 904, the screen 910 shown in FIG. 9B is displayed, and a fundus photon count map 911 and a color bar 916 are displayed on the screen. The photon count map 911 is a color map that is colored according to the number of photons (photon count values) of light incident on the image sensor 137, which is a SPAD sensor. The color bar 916 quantitatively displays the correspondence between color and photon count value. In this modification, fluorescent photography is performed without reducing light with an ND filter, making it possible to photograph minute leakage areas 905 in a fundus image 901. Furthermore, by displaying a fundus photon count map, it is possible to quantitatively measure the amount of leakage in minute leakage areas 915 in a fundus photon count map 915. Here, photon count values ​​are displayed as a color map on the screen, but they may also be displayed as numerical values ​​on the screen.

[0061] As described above, in this modification, a photographing flow in which an ND filter is not used (an ND filter is not inserted) during high-sensitivity photographing has been described. This photographing flow makes it possible to acquire a fundus image with appropriate brightness even in photographing under low light conditions (e.g., fluorescent photography) that are difficult to photograph using an image sensor with general sensitivity.

[0062] (Modification 2 of Embodiment 1) In embodiment 1, a flow for switching between low-sensitivity photography and high-sensitivity photography depending on the photography mode (e.g., still image photography, fluorescent photography, etc.) was described, but a flow for automatically switching between low-sensitivity photography and high-sensitivity photography according to the subject's eye may also be provided.

[0063] The photographing flow for automatically switching between low-sensitivity photographing and high-sensitivity photographing will be described with reference to FIG.

[0064] In step S1001, the imaging control unit 201 starts imaging in response to an operation by the examiner from the operation unit 340, and the process proceeds to step S1003.

[0065] In steps S1003 to S1005, the same operations as in steps S703 to S705 in FIG. 7 are performed, and the process proceeds to step S1007.

[0066] In step S1007, the exposure control unit 203 determines the exposure conditions for shooting in the same manner as in step S707 in FIG. 7, and the process proceeds to step S1008.

[0067] In step S1008, the exposure control unit 203 determines whether the exposure was set within an appropriate exposure adjustment range in step S1007. If the exposure control unit 203 was able to set the exposure within the exposure adjustment range, the process proceeds to step S1009. If the exposure was not able to set the exposure within the exposure adjustment range, the process proceeds to step S1010. For example, if the amount of reflected light from the subject's eye E is low due to miosis or disease, etc., and the image is dark even when adjusted to the upper limit of the dimming range, the process proceeds to step S1010.

[0068] In step S1009, the same low-sensitivity photographing operation as in steps S705 to S709 is performed, and as in step S710, the photographing control unit 201 displays the photographed image on the image display unit 310, and photographing ends.

[0069] In step S1010, the same high-sensitivity photographing operation as in steps S714 to S719 is performed, and as in step S710, the photographing control unit 201 displays the photographed image on the image display unit 310, and photographing ends.

[0070] When low-sensitivity imaging is performed, the image display unit 310 displays screen 1100 of FIG. 11(a). When high-sensitivity imaging is performed, the image display unit 310 displays screen 1110 of FIG. 11(b). Screen 1100 displays display 1102, which indicates that the image was captured using a low-sensitivity imaging element, and screen 1110 displays display 1112, which indicates that the image was captured using a high-sensitivity imaging element. By displaying displays 1102 and 1112, the examiner can identify which imaging element was used to capture the image. Note that displays 1102 and 1112 are examples of identification information. The identification information is not limited to character strings, and may also be a figure or a color.

[0071] In this modified example, exposure control is first performed using the low-sensitivity image sensor 169, and then low-sensitivity shooting and high-sensitivity shooting are switched depending on whether the exposure control was performed correctly. However, exposure control may be first performed using the high-sensitivity image sensor 170, and then low-sensitivity shooting and high-sensitivity shooting may be switched depending on whether the exposure control was performed correctly. By first performing exposure control using the high-sensitivity image sensor 170, it is possible to suppress, for example, miosis of the subject's eye.

[0072] As described above, in this modification, an imaging flow for automatically switching between low-sensitivity imaging and high-sensitivity imaging has been described. According to this imaging flow, when imaging a subject's eye with low fundus reflectance, it is possible to automatically switch to high-sensitivity imaging, thereby obtaining a fundus image with appropriate brightness.

[0073] In the first embodiment, a configuration in which a low-sensitivity image sensor 136 and a high-sensitivity image sensor 137 are mounted has been described. However, if a sufficient dynamic range can be obtained with only the high-sensitivity image sensor 137, a configuration having only the high-sensitivity image sensor 137 may be used. Even with this configuration, a fundus image with appropriate brightness can be acquired. Furthermore, if a sufficient dynamic range cannot be obtained with only the high-sensitivity image sensor 137, a configuration in which both the low-sensitivity image sensor 136 and the high-sensitivity image sensor 137 are mounted may not be used. For example, the image sensors may be detachable. Specifically, for example, when high-sensitivity photography is to be performed, a configuration in which the low-sensitivity image sensor 136 can be removed and the high-sensitivity image sensor 137 can be attached may be used. Even with this configuration, a fundus image with appropriate brightness can be acquired.

[0074] <Embodiment 2> The apparatus shown in the second embodiment is an ophthalmologic apparatus that simultaneously performs low-sensitivity photography and high-sensitivity photography. The configuration of the image sensor in the second embodiment will be described with reference to FIG.

[0075] In the second embodiment, a half mirror 170 is disposed on the optical axis L3 between the imaging lens 134 and the image sensor 136 and the image sensor 137. The half mirror 170 splits light into a transmission direction and a reflection direction, and causes reflected light from the subject's eye E to simultaneously enter the image sensor 136 and the image sensor 137. An ND filter 171 is disposed between the half mirror 170 and the image sensor 137. The ND filter 171 reduces the amount of light incident on the image sensor 137. The image acquisition unit 202 simultaneously acquires images from the image sensor 136 and the image sensor 137. Note that, although the ND filter 171 is disposed between the half mirror 160 and the image sensor 137 in FIG. 12, a configuration in which the ND filter is not used may be adopted by lowering the reflectance of the half mirror 170.

[0076] In the second embodiment, the configurations of the image capturing unit 100 and the control unit 200, and the light control method by the exposure control unit 203 are the same as in the first embodiment.

[0077] <Shooting flow> The imaging flow of the second embodiment will be described with reference to FIG.

[0078] In step S1301, the imaging control unit 201 starts imaging in response to an operation by the examiner from the operation unit 340, and the process proceeds to step S1305.

[0079] In step S1305, the image acquisition unit 202 starts acquiring images simultaneously using the two image sensors, the image sensor 136 and the image sensor 137, and the process proceeds to step S1307.

[0080] In step S1307, the exposure control unit 203 determines the exposure conditions for the image capturing elements 136 and 137. The exposure control unit 203 determines different exposure conditions for each image capturing element for the image capturing element 136 in the same manner as in step S707, and for the image capturing element 137 in the same manner as in step S717. More specifically, the exposure of the low-sensitivity image capturing element 136 is adjusted so that a bright portion of the fundus is given an appropriate brightness. For example, the exposure is adjusted so that the highly reflective optic disc (bright portion) is given an appropriate brightness. The exposure of the high-sensitivity image capturing element 137 is adjusted so that a dark portion of the fundus is given an appropriate brightness. For example, the exposure is adjusted so that the low-reflective macula (dark portion) is given an appropriate brightness. When the exposure control unit 203 completes the exposure control, the process proceeds to step S1308.

[0081] In step S1308, the image acquisition unit 202 acquires the image signals of the image sensor 136 and the image sensor 137 captured under the exposure conditions determined in step S1307. The low-sensitivity image sensor 136 acquires an image 1400 adjusted so that bright areas have appropriate brightness, as shown in Fig. 14(a). The high-sensitivity image sensor 137 acquires an image 1401 adjusted so that dark areas have appropriate brightness, as shown in Fig. 14(b).

[0082] When the image acquisition unit 202 has completed acquisition of the image signal and transmitted the image signal to the image generation unit 204, the process proceeds to step S1309.

[0083] In step S1309, the image generation unit 204 performs adjustments such as different brightness correction, contrast correction, and gamma correction on the two received images (image 1400 and image 1401) to generate fundus images. There are differences in sensitivity, color, position, and distortion between the two images captured by different image sensors. Therefore, the image generation unit 204 corrects these differences between the two images to match each other, and generates two corrected images. After completing generation of the two corrected images, the image generation unit 204 proceeds to step S1310.

[0084] In step S1310, the image generation unit 204 combines the two corrected images to generate a high dynamic range combined image (HDR image). The combined image is shown in Fig. 14(c). Once the combined image is generated, the process proceeds to step S1311.

[0085] In step S1311, similarly to step S710, the imaging control unit 201 displays the captured image on the image display unit 310, and then the imaging process ends.

[0086] As described above, an ophthalmologic apparatus that simultaneously performs low-sensitivity photography and high-sensitivity photography has been described in Embodiment 2. Although there are various parts of the fundus that have different reflectances, by simultaneously performing low-sensitivity photography and high-sensitivity photography, a high dynamic range composite image (HDR image) can be obtained.

[0087] As described above, in the first and second embodiments, the present disclosure is described as being applied to an ophthalmic apparatus. However, the present disclosure can be applied not only to ophthalmic apparatuses but also to apparatuses that capture images of other subjects. For example, the present disclosure can be applied to digital cameras and surveillance cameras.

[0088] (Other embodiments) The disclosed technology can also be realized by executing the following process. That is, the disclosed technology can also be realized by supplying software (programs) that realize one or more functions of the various embodiments described above to a system or device via a network or a storage medium, and having a computer (or a CPU, MPU, or the like) of the system or device read and execute the programs. The computer has one or more processors or circuits, and may include multiple separate computers or a network of multiple separate processors or circuits to read and execute computer-executable instructions. In this case, the processor or circuit may include a central processing unit (CPU), a microprocessing unit (MPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), or a field-programmable gateway (FPGA). The processor or circuit may also include a digital signal processor (DSP), a data flow processor (DFP), or a neural processing unit (NPU).

[0089] (Configuration 1) an imaging unit that captures an image of the fundus of the subject's eye using a first imaging element and a second imaging element having higher sensitivity than the first imaging element; a control unit that controls the amount of light incident on the imaging unit; An ophthalmic apparatus comprising: The control unit When the imaging unit captures an image using the first imaging element, the amount of light is controlled within a first range having a first amount of light as a lower limit; an ophthalmologic apparatus that controls the amount of light within a second range, the lower limit of which is a second amount of light that is lower than the first amount of light, when the imaging unit captures an image using the second imaging element;

[0090] (Configuration 2) The ophthalmologic apparatus according to Configuration 1, wherein the imaging unit photographs the fundus of the subject's eye by switching between the first imaging element and the second imaging element.

[0091] (Configuration 3) the first range has the first light amount as a lower limit and a third light amount as an upper limit; The ophthalmologic apparatus according to configuration 1 or 2, wherein the second range has the second light amount as its lower limit and a fourth light amount that is greater than the first light amount and less than the third light amount as its upper limit.

[0092] (Configuration 4) further comprising an illumination unit that illuminates the subject's eye, 4. The ophthalmologic apparatus according to any one of configurations 1 to 3, wherein the control unit controls the amount of light incident on the imaging unit by changing the amount of light emitted by the illumination unit.

[0093] (Configuration 5) the illumination unit has a plurality of light sources, 5. The ophthalmologic apparatus according to configuration 4, wherein the control unit controls the amount of light incident on the imaging unit by changing the number of the light sources that emit light.

[0094] (Configuration 6) an optical member is further provided between the illumination unit and the subject's eye or between the subject's eye and the imaging unit; 6. The ophthalmologic apparatus according to configuration 4 or 5, wherein the control unit controls the optical member to control the amount of light incident on the imaging unit.

[0095] (Configuration 7) 7. The ophthalmologic apparatus according to configuration 6, wherein the optical member is at least one of an ND filter, a diaphragm, and a half mirror.

[0096] (Configuration 8) a display control unit that controls displaying the fundus image captured by the imaging unit on a display unit; The display control unit An ophthalmologic device according to any one of configurations 1 to 7, which controls the display of identification information on a display unit to identify whether the fundus image is a fundus image photographed using the first imaging element or a fundus image photographed using the second imaging element.

[0097] (Configuration 9) a display control unit that controls displaying the fundus image captured by the imaging unit on a display unit; The display control unit An ophthalmologic device according to any one of configurations 1 to 8, which controls the display of a composite image on a display unit, the composite image being a combination of a fundus image captured using the first imaging element and a fundus image captured using the second imaging element.

[0098] (Configuration 10) the first imaging element is a CCD sensor or a CMOS sensor, 10. The ophthalmologic apparatus according to any one of configurations 1 to 9, wherein the second imaging element is a SPAD sensor.

[0099] (Configuration 11) an imaging unit that captures an image of the fundus of the subject's eye using a SPAD sensor; an illumination unit that illuminates the fundus; at least one optical member selected from the group consisting of an optical member for attenuating the illumination and an optical member for attenuating the light reflected from the fundus; An ophthalmic device comprising:

[0100] (Method 1) an imaging step of capturing an image of the fundus of the subject's eye using a first imaging element and a second imaging element having higher sensitivity than the first imaging element; a control step of controlling the amount of light incident on the imaging unit; A control method for an ophthalmic apparatus comprising: The control step includes: When capturing an image using the first image sensor in the imaging step, the amount of light is controlled within a first range having a first amount of light as a lower limit; A control method for an ophthalmic apparatus, which controls the amount of light within a second range, the lower limit of which is a second amount of light lower than the first amount of light, when capturing an image using the second image capturing element in the imaging step.

[0101] (Program 1) A program that causes a computer to execute the method for controlling an ophthalmologic apparatus according to Method 1.

[0102] (Configuration 12) an imaging unit that captures an image of the fundus of the subject's eye using a CMOS sensor and a SPAD sensor; a control unit that controls the amount of light incident on the imaging unit; An ophthalmic apparatus comprising: The control unit When the imaging unit captures an image using the CMOS sensor, the imaging unit controls the amount of light within a first range having a first amount of light as a lower limit; an ophthalmic apparatus that controls the amount of light within a second range, the lower limit of which is a second amount of light lower than the first amount of light, when the imaging unit captures an image using the SPAD sensor;

[0103] (Configuration 13) an imaging unit that captures an image of a subject using a first imaging element and a second imaging element having a higher sensitivity than the first imaging element; a control unit that controls the amount of light incident on the imaging unit; An imaging device comprising: The control unit When the imaging unit captures an image using the first imaging element, the amount of light is controlled within a first range having a first amount of light as a lower limit; an imaging device that controls the amount of light within a second range, the lower limit of which is a second amount of light that is lower than the first amount of light, when the imaging unit captures an image using the second imaging element; [Explanation of symbols]

[0104] 100 Imaging unit 200 control section 300 Display 301 Operation section

Claims

1. an imaging unit that captures an image of the fundus of the subject's eye using a first imaging element and a second imaging element having higher sensitivity than the first imaging element; a control unit that controls the amount of light incident on the imaging unit; An ophthalmic apparatus comprising: The control unit When the imaging unit captures an image using the first imaging element, the amount of light is controlled within a first range having a first amount of light as a lower limit; an ophthalmic apparatus that controls the amount of light within a second range having a second light amount lower than the first light amount as a lower limit when the imaging unit captures an image using the second imaging element;

2. The ophthalmologic apparatus according to claim 1 , wherein the imaging unit captures an image of the fundus of the subject's eye by switching between the first imaging element and the second imaging element.

3. the first range has the first light amount as a lower limit and a third light amount as an upper limit; The ophthalmologic apparatus according to claim 1 , wherein the second range has the second light amount as a lower limit and a fourth light amount that is greater than the first light amount and less than the third light amount as an upper limit.

4. further comprising an illumination unit that illuminates the subject's eye, The ophthalmologic apparatus according to claim 1 , wherein the control unit controls the amount of light incident on the imaging unit by changing the amount of light emitted by the illumination unit.

5. the illumination unit has a plurality of light sources, The ophthalmologic apparatus according to claim 4 , wherein the control unit controls the amount of light incident on the imaging unit by changing the number of the light sources that emit light.

6. an optical member is further provided between the illumination unit and the subject's eye or between the subject's eye and the imaging unit; The ophthalmologic apparatus according to claim 4 , wherein the control unit controls the amount of light incident on the imaging unit by controlling the optical member.

7. 7. The ophthalmologic apparatus according to claim 6, wherein the optical member is at least one of an ND filter, a diaphragm, and a half mirror.

8. a display control unit that controls displaying the fundus image captured by the imaging unit on a display unit; The display control unit The ophthalmologic device according to claim 1, wherein the display unit is controlled to display identification information that identifies whether the fundus image is a fundus image captured using the first imaging element or a fundus image captured using the second imaging element.

9. a display control unit that controls displaying the fundus image captured by the imaging unit on a display unit; The display control unit The ophthalmologic apparatus according to claim 1 , wherein the apparatus controls to display a composite image on a display unit, the composite image being a combination of a fundus image captured using the first image sensor and a fundus image captured using the second image sensor.

10. the first imaging element is a CCD sensor or a CMOS sensor, The ophthalmologic apparatus according to claim 1 , wherein the second image pickup element is a SPAD sensor.

11. an imaging unit that captures an image of the fundus of the subject's eye using a SPAD sensor; an illumination unit that illuminates the fundus; at least one optical member selected from the group consisting of an optical member for attenuating the illumination and an optical member for attenuating the light reflected from the fundus; An ophthalmic device comprising:

12. an imaging step of imaging a fundus of the subject's eye using a first imaging element and a second imaging element having higher sensitivity than the first imaging element; a control step of controlling the amount of light incident on the imaging unit; A control method for an ophthalmic apparatus comprising: The control step includes: When photographing using the first image pickup element in the photographing step, the amount of light is controlled within a first range having a first amount of light as a lower limit; A control method for an ophthalmic apparatus, which controls the amount of light within a second range, the lower limit of which is a second amount of light lower than the first amount of light, when capturing an image using the second image capturing element in the imaging step.

13. A program that causes a computer to execute the method for controlling an ophthalmologic apparatus according to claim 12.

14. an imaging unit that captures an image of the fundus of the subject's eye using a CMOS sensor and a SPAD sensor; a control unit that controls the amount of light incident on the imaging unit; An ophthalmic apparatus comprising: The control unit When the imaging unit captures an image using the CMOS sensor, the amount of light is controlled within a first range having a first amount of light as a lower limit; an ophthalmologic apparatus that controls the amount of light within a second range having a second light amount lower than the first light amount as a lower limit when the imaging unit captures an image using the SPAD sensor;

15. an imaging unit that captures an image of a subject using a first imaging element and a second imaging element having a higher sensitivity than the first imaging element; a control unit that controls the amount of light incident on the imaging unit; An imaging device comprising: The control unit When the imaging unit captures an image using the first imaging element, the amount of light is controlled within a first range having a first amount of light as a lower limit; an imaging device that, when the imaging section captures an image using the second imaging element, controls the amount of light within a second range having a second amount of light lower than the first amount of light as a lower limit;

Images