JP7609953B2 - Ophthalmic device and control method thereof - Google Patents

Description

This invention relates to an ophthalmic device and a control method thereof.

In recent years, eye examinations using ophthalmic devices have been performed for screening. Such ophthalmic devices are expected to be used for self-examination, and there is a demand for them to be even smaller and lighter.

For example, Patent Documents 1 and 2 disclose an ophthalmic device that uses slit light to illuminate the subject's eye in a pattern and detects the return light with a CMOS (Complementary Metal Oxide Semiconductor) image sensor. This ophthalmic device is capable of acquiring an image of the subject's eye with a simple configuration by adjusting the illumination pattern and the timing of light reception by the CMOS image sensor.

In this type of ophthalmic device, as in other ophthalmic devices, it is possible to obtain images with higher resolution by performing pattern illumination when the focus state of the slit light is optimal. Patent Documents 1 and 2 disclose a method of driving a focusing mechanism using the amount of reflected light of illumination light from the subject's eye.

U.S. Pat. No. 7,831,106 U.S. Pat. No. 8,237,835

However, the amount of illumination light reflected from the test eye varies depending on the condition of the test eye or the irradiation position of the illumination light. Therefore, depending on the test eye, the amount of illumination light reflected may be small, making it difficult to move the focal position of the slit light to the optimal position. In other words, it is difficult to reproducibly achieve the optimal focusing state.

This invention was made to solve these problems, and its purpose is to provide a new technology that uses a simple configuration to identify the optimal focus state with good reproducibility.

A first aspect of some embodiments is an ophthalmic device that includes a projection unit that projects a pattern light having a projection shape extending at least in a first direction onto a test eye, an acquisition unit that acquires a received light image corresponding to an aperture shape extending at least in a second direction intersecting the first direction based on a detection result of return light of the pattern light from the test eye, and an identification unit that identifies a focus state of the pattern light based on a luminance distribution of the received light image.

A second aspect of some embodiments is an ophthalmic device that includes a projection unit that projects pattern light of a projection shape extending at least in a first direction onto a test eye, an acquisition unit that acquires a received-light image corresponding to an aperture shape extending at least in the first direction based on a detection result of return light of the pattern light from the test eye, and an identification unit that identifies a focus state of the pattern light based on a luminance distribution in a second direction intersecting the first direction in one or more received-light images acquired by the acquisition unit.

In a third aspect of some embodiments, in the first or second aspect, the determination unit includes a control unit that determines the focus control content of the pattern light based on the luminance distribution in the second direction in the received light image, and performs focus control of the pattern light based on the determined focus control content.

In a fourth aspect of some embodiments, in the third aspect, the control unit performs the focus control so that the bright or dark area moves to a predetermined position.

A fifth aspect of some embodiments is the third or fourth aspect, which includes a focusing mechanism disposed in the optical paths of the pattern light and the return light, and the control unit controls the focusing mechanism based on the identified focusing control content.

In a sixth aspect of some embodiments, in any one of the first to fifth aspects, the projection unit includes a projector that outputs a pattern light whose projection shape is changeable.

In a seventh aspect of some embodiments, in the sixth aspect, the projection unit outputs a pattern light of a first projection shape for identifying the focus state, and after focusing control of the pattern light, outputs a pattern light of a second projection shape different from the first projection shape, and the acquisition unit acquires a received light image based on the detection result of the return light of the pattern light of the second projection shape.

In an eighth aspect of some embodiments, in any of the first to seventh aspects, the acquisition unit includes an image sensor that detects the return light, and acquires the received light image using a rolling shutter method.

A ninth aspect of some embodiments is a control method for an ophthalmic device, including a projection step of projecting a pattern light having a projection shape extending at least in a first direction onto a test eye, an acquisition step of acquiring a received light image corresponding to an aperture shape extending at least in a second direction intersecting the first direction based on a detection result of return light of the pattern light from the test eye, and an identification step of identifying a focus state of the pattern light based on a luminance distribution of the received light image.

A tenth aspect of some embodiments is a method for controlling an ophthalmic device, comprising: a projection step of projecting a pattern light having a projection shape extending at least in a first direction onto a test eye; an acquisition step of acquiring a received light image corresponding to an aperture shape extending at least in the first direction based on a detection result of return light of the pattern light from the test eye; and a determination step of identifying a focus state of the pattern light based on a luminance distribution in a second direction intersecting the first direction in one or more received light images acquired in the acquisition step.

In an eleventh aspect of some embodiments, in the ninth or tenth aspect, the specifying step includes a control step of specifying a focus control content of the pattern light based on the luminance distribution in the second direction in the received light image, and performing focus control of the pattern light based on the specified focus control content.

In a twelfth aspect of some embodiments, in any of the ninth to eleventh aspects, the projection step includes a first projection step of outputting a pattern light of a first projection shape for identifying the focus state, and a second projection step of outputting a pattern light of a second projection shape different from the first projection shape after focusing control of the pattern light, and the acquisition step includes a first acquisition step of acquiring a received light image corresponding to the opening shape based on a detection result of return light of the pattern light of the first projection shape projected in the first projection step, and a second acquisition step of acquiring a received light image based on a detection result of return light of the pattern light of the second projection shape projected in the second projection step.

In a thirteenth aspect of some embodiments, in any of the ninth to twelfth aspects, the acquisition step acquires the received light image using a rolling shutter method based on the detection result of the return light.

The configurations relating to the above-mentioned aspects can be combined in any way.

This invention provides a new technology that uses a simple configuration to identify the optimal focus state with good reproducibility.

1 is a schematic diagram illustrating an example of the configuration of an ophthalmologic apparatus according to an embodiment. 1 is a schematic diagram illustrating an example of the configuration of an ophthalmologic apparatus according to an embodiment. 1 is a schematic diagram illustrating an example of the configuration of an ophthalmologic apparatus according to an embodiment. 4A to 4C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. 4A to 4C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. 4A to 4C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. 4A to 4C are diagrams illustrating the operation of the ophthalmologic apparatus according to the embodiment. FIG. 4 is a flow diagram of an example of the operation of the ophthalmologic apparatus according to the embodiment. FIG. 13 is a schematic diagram illustrating an example of the configuration of an ophthalmologic apparatus according to a modified example of the embodiment. 10A to 10C are diagrams illustrating the operation of an ophthalmologic apparatus according to a modified example of an embodiment. 10A to 10C are diagrams illustrating the operation of an ophthalmologic apparatus according to a modified example of an embodiment. 10A to 10C are diagrams illustrating the operation of an ophthalmologic apparatus according to a modified example of an embodiment. 10A to 10C are diagrams illustrating the operation of an ophthalmologic apparatus according to a modified example of an embodiment. 10A to 10C are diagrams illustrating the operation of an ophthalmologic apparatus according to a modified example of an embodiment. FIG. 11 is a flowchart of an operation example of an ophthalmologic apparatus according to a modified example of an embodiment.

An example of an embodiment of an ophthalmic device and a control method thereof according to the present invention will be described in detail with reference to the drawings. The contents of the documents described in this specification may be appropriately used as the contents of the following embodiment.

The ophthalmic apparatus according to the embodiment includes a projection system that projects a pattern light onto the subject's eye, and a light receiving system that receives the return light of the pattern light from the subject's eye, and is capable of acquiring an image of the fundus of the subject's eye based on the reception result of the return light obtained by the light receiving system. In some embodiments, the ophthalmic apparatus acquires an image of the anterior segment of the subject's eye using a configuration similar to that described above.

For example, the projection system projects a slit-shaped (line-shaped) pattern of light extending at least in a first direction onto the subject's eye. The ophthalmic device obtains a received light image corresponding to an opening shape extending at least in a second direction from the result of receiving the return light obtained by the light receiving system, and identifies the focusing state of the pattern of light based on the luminance distribution in the second direction in the received light image. Here, the second direction is a direction intersecting the first direction. In some embodiments, the second direction is different from a direction perpendicular to the first direction.

In this specification, the "direction" of the pattern light, the "direction" of the aperture shape or the received light image, and the aperture direction do not refer to the direction at each position in the absolute coordinate system, but rather refer to the direction on a specific optical surface (for example, the light receiving surface in a light receiving system).

[Optical system configuration]
Figures 1 to 3 show block diagrams of an example configuration of an ophthalmic apparatus according to an embodiment. Figures 1 and 2 show block diagrams of an example configuration of an optical system of an ophthalmic apparatus 1 according to an embodiment. Figure 3 shows a block diagram of an example configuration of a control system of the ophthalmic apparatus 1. In Figures 1 to 3, similar parts are given the same reference numerals and descriptions thereof will be omitted as appropriate.

The ophthalmic device 1 projects a pattern light onto the subject's eye E, receives the returned light to determine the focus state of the pattern light, and performs focus control based on the determined focus state. After focus control, the ophthalmic device 1 projects a pattern light onto the subject's eye E again, and receives the returned light to obtain an image of the subject's eye E (fundus).

The ophthalmic device 1 includes a projection system 10, a light receiving system 20, an image processing unit 30, and an image output unit 40.

The ophthalmic device 1 projects pattern light onto the subject's eye E in a focus control mode for performing focus control and in an imaging mode for performing imaging, and obtains a received light image in each mode.

[Focus control mode]
The projection system 10 projects a pattern light for focus control, which has a projection shape extending at least in a direction (hereinafter, sometimes referred to as the aperture crossing direction) intersecting with the aperture direction (the direction corresponding to the aperture direction), onto the subject's eye E. The light receiving system 20 receives the return light of the pattern light projected onto the subject's eye E by the projection system 10. The image processing unit 30 acquires a received light image corresponding to at least the aperture shape extending in the aperture direction from the result of receiving the return light by the light receiving system 20. The image processing unit 30 specifies the focusing state (whether or not the pattern light is in focus) based on the luminance distribution in the aperture crossing direction in the received light image. The image processing unit 30 can specify the control contents for the focusing mechanism described later based on the luminance distribution. The control unit described later performs focusing control according to the control contents specified by the image processing unit 30 (i.e., controls the focusing mechanism described later).

[Shooting mode]
After focus control, the projection system 10 sequentially projects pattern light for photography having a projection shape (e.g., slit-shaped, line-shaped) extending in the opening direction onto the subject's eye E in a direction perpendicular to the opening direction. In some embodiments, the projection shape in the focus control mode and the projection shape in the photography mode are different from each other. The light receiving system 20 receives return light of the pattern light projected onto the subject's eye E by the projection system 10. The image processing unit 30 acquires an image of the fundus of the subject's eye E by sequentially acquiring received light images corresponding to the opening shape while shifting the opening shape in a direction perpendicular to the opening direction (or the opening crossing direction) from the result of receiving the return light by the light receiving system 20.

(Projection system 10)
The projection system 10 includes a pattern light generating unit 11 , a smoothing unit 12 , and an optical system 13 .

(Pattern Light Generator 11)
The pattern light generating unit 11 is controlled by a control unit described later and generates pattern light of a projection shape extending at least in the aperture crossing direction. The pattern light generating unit 11 is capable of selectively generating pattern light of two or more projection shapes and selectively projecting the pattern light onto two or more projection regions on the subject's eye E (fundus).

As shown in FIG. 2, the pattern light generating unit 11 includes a light source 11A, an optical system 11B, and a spatial light modulator 11C. An example of a pattern light generating unit 11 having such a configuration is a projector. That is, the pattern light generating unit 11 includes a light source 11A, an optical system 11B, and a spatial light modulator 11C corresponding to the type of projector. The light source 11A can be placed at a position that is approximately optically conjugate with the imaging site of the subject's eye E (e.g., the fundus, the anterior segment).

In some embodiments, light source 11A is a light source that can switch between outputting light in the infrared or near-infrared region and light in the visible region. For example, light source 11A outputs light in the infrared or near-infrared region when outputting a pattern light (focus indicator) for focus control in focus control mode, and outputs light in the visible region when photographing the desired imaging area in imaging mode.

In some embodiments, the pattern light generating unit 11 has the function of a DLP (Digital Light Processing (registered trademark)) type projector using a digital micromirror device. In this case, in a first configuration example, a single digital micromirror device is used for light in the infrared or near-infrared region. In a second configuration example, a digital micromirror device common to the RGB color components is used for light from a white light source. In a third configuration example, a digital micromirror device is used for each RGB color component for light from a white light source.

In the first configuration example, the light source 11A includes, for example, an LED (Light Emitting Diode) light source that emits light in the infrared region or near-infrared region. The optical system 11B includes a relay optical system and an optical lens. The spatial light modulator 11C includes a digital micromirror device in which a plurality of mirror elements are arranged two-dimensionally. Each of the plurality of mirror elements can be controlled independently. The spatial light modulator 11C can include a projection lens for projecting the light spatially modulated by the digital micromirror device.

In the second configuration example, the light source 11A includes a white light source or a light source capable of outputting light of each color component of RGB. The optical system 11B includes a color wheel for outputting light of each color component of RGB in a time-division manner from the light from the light source 11A, a relay optical system, and an optical lens. The spatial light modulator 11C includes a digital micromirror device in which multiple mirror elements are arranged two-dimensionally. The spatial light modulator 11C may include a projection lens for projecting the light spatially modulated by the digital micromirror device.

In the third configuration example, the light source 11A includes a white light source or a light source capable of outputting light of each of the RGB color components. The optical system 11B includes a relay optical system and an optical lens. The spatial light modulator 11C includes a plurality of digital micromirror devices provided for each of the RGB color components. The spatial light modulator 11C may include a projection lens for projecting the light spatially modulated by the digital micromirror devices.

In some embodiments, the pattern light generating unit 11 has the function of a reflective liquid crystal projector using LCoS (Liquid Crystal on Silicon). In this case, the light source 11A includes a white light source. The optical system 11B includes one or more reflecting mirrors, one or more dichroic mirrors, and one or more polarizing beam splitters. The spatial light modulator 11C includes a reflective liquid crystal panel for each RGB color component, a cross dichroic prism for synthesizing the light spatially modulated for each color component, and a projection lens for projecting the synthesized light.

In some embodiments, the pattern light generating unit 11 has the function of a transmissive liquid crystal projector. In this case, the light source 11A includes a white light source. The optical system 11B includes one or more reflecting mirrors and one or more dichroic mirrors. The spatial light modulator 11C includes a transmissive liquid crystal panel for each RGB color component, a cross dichroic prism for synthesizing the light spatially modulated for each color component, and a projection lens for projecting the synthesized light.

In some embodiments, the pattern light generating unit 11 has the functionality of a known projector that uses MEMS (Micro Electro Mechanical Systems).

The above-described projector functions as a pixelated pattern light generator. Note that the configuration of the above-described projector is well known, so a detailed description will be omitted. The pattern light generating unit 11 is capable of outputting pattern light (illumination light) corresponding to an illumination pattern whose shape and projection position can be arbitrarily changed.

The pattern light generating unit 11 is controlled by the control unit described below and generates pattern light of any projection shape. The projection shape can be set by the user, for example, using the operation unit described below. When the user uses the operation unit to specify a shape pattern, outer shape, size, etc., the control unit can specify an illumination pattern based on the specified shape pattern, etc., and control the spatial light modulator 11C based on the specified illumination pattern.

(Smoothing unit 12)
The smoothing unit 12 smoothes the pattern light (light amount distribution of the pattern light) generated by the pattern light generating unit 11 so that the light amount distribution is diffused at least in the aperture direction (the light amount distribution spreads at least in the aperture direction). That is, the smoothing unit 12 smoothes the pattern light so that the diffusion characteristics in the aperture direction and the aperture crossing direction are different. Specifically, the transmission angle θ1 of the transmitted light with respect to a predetermined incidence angle θ0 for the aperture direction component of the pattern light is larger than the transmission angle θ2 of the transmitted light with respect to a predetermined incidence angle θ0 for the aperture crossing direction component of the pattern light.

The smoothing unit 12 can be positioned at a position that is approximately optically conjugate with the imaging area of the subject's eye E (e.g., the fundus, the anterior segment).

In some embodiments, the smoothing section 12 includes a diffusion filter (optical low-pass filter). In some embodiments, the smoothing section 12 includes a birefringent plate having birefringence.

(Optical System 13)
The optical system 13 includes a relay optical system for relaying the pattern light smoothed by the smoothing unit 12. In some embodiments, the optical system 13 further includes a collimator lens and an optical scanner. In this case, the optical scanner is capable of deflecting the pattern light under the control of a control unit described later.

The pattern light that passes through the optical system 13 is reflected by the optical multiplexer/demultiplexer 50 and directed to the optical system 51.

(Optical multiplexer/demultiplexer 50)
The optical multiplexer/demultiplexer 50 guides the light from the projection system 10 to the optical system 51, and guides the light from the optical system 51 to the light receiving system 20. The function of the optical multiplexer/demultiplexer 50 is the same as that of a beam splitter. , or a dichroic mirror.

(Optical system 51)
The optical system 51 is disposed between the optical multiplexer/demultiplexer 50 and the subject's eye E. The optical system 51 includes a focusing mechanism 52. In some embodiments, the optical system 51 further includes an objective lens disposed between the focusing mechanism 52 and the subject's eye E. In some embodiments, the optical system 51 includes a front lens for moving the focal position of the pattern light to the vicinity of the anterior segment. In this case, the front lens is provided so as to be insertable into and detachable from the optical path of the pattern light.

Examples of the focusing mechanism 52 include a focusing lens that can move along the optical axis (the direction of the optical path of the pattern light), a liquid lens with a changeable refractive index, a liquid crystal lens with a changeable refractive index, and an objective lens that can move along the optical axis.

The focusing lens or objective lens can be moved automatically or manually in the optical axis direction. For example, the ophthalmic device 1 includes a movement mechanism that moves at least one of the focusing lens and the objective lens in the optical axis direction, and the control unit controls the movement mechanism to move at least one of the focusing lens and the objective lens in the optical axis direction, thereby performing focusing control. Also, for example, the user can manually adjust the focus state by operating the movement mechanism to move at least one of the focusing lens and the objective lens in the optical axis direction.

In addition, the control unit can perform focusing control by controlling the liquid lens or liquid crystal lens to change the refractive index.

The pattern light from the projection system 10 reflected by the optical multiplexer/demultiplexer 50 is projected onto the subject's eye E via the optical system 51. The return light of the pattern light from the subject's eye E passes through the optical system 51, is reflected by the optical multiplexer/demultiplexer 50, and is guided to the light receiving system 20.

(Light receiving system 20)
The light receiving system 20 includes an optical system 21 and an image sensor 22 .

(Optical system 21)
Return light of the pattern light from the subject's eye reflected by the optical multiplexer/demultiplexer 50 is incident on the optical system 21. The optical system 21 includes an imaging lens that forms an image of the return light on a detection surface of the image sensor 22. In some embodiments, the optical system 21 further includes a relay optical system for relaying the return light.

(Image sensor 22)
The image sensor 22 realizes a function as a pixelated light receiver. In this embodiment, the image sensor 22 includes a CMOS image sensor. That is, the image sensor 22 includes a plurality of photodiodes arranged two-dimensionally, a plurality of vertical signal lines, and a horizontal signal line. The plurality of vertical signal lines are provided for each group of photodiodes in the vertical direction. Each vertical signal line is selectively electrically connected to a group of photodiodes in which charges corresponding to the light reception results are accumulated. The horizontal signal line is selectively electrically connected to the plurality of vertical signal lines. As a result, the photodiodes provided for each pixel accumulate charges corresponding to the light reception results of the return light, and the accumulated charges are read out, for example, for each group of photodiodes in the horizontal direction. That is, a voltage corresponding to the charge accumulated in each photodiode is supplied to the vertical signal line for each line in the horizontal direction. The plurality of vertical signal lines are selectively electrically connected to the horizontal signal line. The light reception results of the plurality of photodiodes arranged two-dimensionally are read out by performing the above-mentioned read operation for each horizontal line in the vertical direction.

The detection surface of the image sensor 22 can be positioned at a position that is approximately optically conjugate with the imaging site of the subject's eye E (e.g., the fundus, the anterior segment). In other words, the detection surface of the image sensor 22 can be positioned at a position that is approximately optically conjugate with the light source 11A.

Such read control of the image sensor 22 can be performed under control of the control unit described below.

The control unit can also read out the results of receiving the return light from the image sensor 22 using a so-called rolling shutter method. This allows readout control corresponding to the desired aperture shape to be performed, thereby acquiring a received light image corresponding to that aperture shape. This type of control is disclosed, for example, in the specification of U.S. Patent No. 8,237,835.

Furthermore, the control unit can control the pattern light generating unit 11 to sequentially generate slit-shaped (line-shaped) pattern light extending at least in the opening direction in a direction perpendicular to the opening direction. As disclosed in U.S. Pat. No. 8,237,835 and the like, the control unit synchronizes the timing of generating the pattern light by the pattern light generating unit 11 with the timing of reading the result of receiving the return light from the image sensor 22 using the rolling shutter method. This makes it possible to obtain an image of the subject's eye with a simple configuration.

(Image Processing Unit 30)
The image processing unit 30 performs various image processing and analysis processing on the received-light image obtained by the image sensor 22. The image processing includes a noise removal process for the received-light image and a brightness correction process for making it easier to identify a specific portion depicted in the received-light image. The analysis processing includes a process for specifying the focusing state, which will be described later, and a process for specifying the control content for performing the focusing control, which will be described later.

The image processing unit 30 is capable of acquiring a light reception image corresponding to any aperture shape based on the light reception results read out from the image sensor 22 by the rolling shutter method under control of the control unit. The image processing unit 30 acquires a light reception image of an aperture shape corresponding to the pattern light of the projection shape for focus control (first projection shape), and also acquires a light reception image of an aperture shape corresponding to the pattern light of the projection shape for shooting (second projection shape). This allows the image processing unit 30 to acquire a light reception image corresponding to the aperture shape for focus control, and after focus control, a light reception image corresponding to the aperture shape (the same or different from the aperture shape during focus control).

In some embodiments, the optical system 21 includes an aperture stop disposed between the imaging lens and the image sensor 22. In this case, the return light that has passed through the aperture stop is imaged on the detection surface of the image sensor 22. Therefore, the image processing unit 30 can obtain a light reception image corresponding to the aperture shape of the aperture stop based on the light reception result read out from the image sensor 22 by the global shutter method under the control of the control unit.

The image processing unit 30 also determines the focus state of the pattern light based on the luminance distribution in the aperture direction (or aperture crossing direction) in the acquired received light image. In some embodiments, the focus state indicates whether or not the focal position of the pattern light approximately coincides with the desired illumination position.

The image processing unit 30 also determines the amount and direction of movement of the focal position of the pattern light based on the luminance distribution in the aperture intersection direction in the acquired received light image.

The detailed operation of the image processing unit 30 will be described later.

The image processing unit 30 includes a processor and performs processing according to a program stored in a memory unit or the like to realize the above functions.

In this specification, the term "processor" refers to a circuit such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), or a programmable logic device (e.g., an SPLD (Simple Programmable Logic Device), a CPLD (Complex Programmable Logic Device), or an FPGA (Field Programmable Gate Array)). The processor realizes the functions of the embodiment by, for example, reading and executing a program stored in a memory circuit or a storage device.

(Image Output Unit 40)
The image output unit 40 displays various information under the control of the control unit described below. For example, the image output unit 40 outputs a received-light image obtained by the image processing unit 30. The received-light image obtained by the image processing unit 30 includes a received-light image acquired for focus control and a received-light image (photographed image) obtained by projecting the pattern light again after focus control.

The image output unit 40 is configured to include a display device such as a flat panel display, such as an LCD (Liquid Crystal Display).

(Other configurations)
In some embodiments, the ophthalmic apparatus 1 further includes a fixation projection system. For example, the optical path of the fixation projection system is coupled to the optical path of the pattern light in the optical system configuration shown in FIG. 1. The fixation projection system can present an internal fixation target or an external fixation target to the subject's eye E. When presenting an internal fixation target to the subject's eye E, the fixation projection system includes an LCD that displays the internal fixation target under control of the control unit, and projects the fixation light beam output from the LCD onto the fundus of the subject's eye E. The LCD is configured to be able to change the display position of the fixation target on its screen. By changing the display position of the fixation target on the LCD, it is possible to change the projection position of the fixation target on the fundus of the subject's eye E. The display position of the fixation target on the LCD can be specified by the user using the operation unit.

In some embodiments, the fixation projection system includes, instead of an LCD, a panel on which, for example, multiple LEDs are arranged, and is configured to project the fixation target by lighting up any one of the LEDs.

In addition, fixation can be induced by changing the projection position of the fixation target on the fundus of the subject's eye E, making it possible to change the observation direction.

In some embodiments, the ophthalmic device 1 includes an alignment system. In some embodiments, the alignment system includes an XY alignment system and a Z alignment system. The XY alignment system is used to align the device optical system and the subject's eye E in a direction intersecting the optical axis of the device optical system (objective lens). The Z alignment system is used to align the device optical system and the subject's eye E in the direction of the optical axis of the ophthalmic device 1 (objective lens).

For example, the XY alignment system projects a bright spot in the infrared or near-infrared region onto the subject's eye E. The image processing unit 30 acquires an anterior segment image of the subject's eye E onto which the bright spot is projected, and determines the displacement between the bright spot image depicted in the acquired anterior segment image and the alignment reference position. The control unit, which will be described later, moves the device optical system and the subject's eye E relatively in a direction intersecting the direction of the optical axis using a movement mechanism (not shown) so that the determined displacement is cancelled.

For example, the Z alignment system projects alignment light in the infrared or near-infrared region from a position off the optical axis of the device optical system, and receives the alignment light reflected by the anterior segment of the subject's eye E. The image processing unit 30 determines the distance of the subject's eye E from the device optical system based on the receiving position of the alignment light, which changes depending on the distance of the subject's eye E from the device optical system. The control unit, which will be described later, moves the device optical system and the subject's eye E relatively in the direction of the optical axis using a movement mechanism (not shown) so that the determined distance becomes the desired working distance.

In some embodiments, the function of the alignment system is realized by two or more anterior segment cameras arranged at a position off the optical axis of the device optical system. For example, as disclosed in JP 2013-248376 A, the image processing unit 30 analyzes anterior segment images of the subject's eye E acquired substantially simultaneously by two or more anterior segment cameras, and identifies the three-dimensional position of the subject's eye E using a known trigonometric method. The control unit, which will be described later, moves the device optical system and the subject's eye E three-dimensionally relative to each other using a movement mechanism (not shown) so that the optical axis of the device optical system approximately coincides with the axis of the subject's eye E and the distance of the device optical system to the subject's eye E is a predetermined working distance.

[Control system configuration]
The control system of the ophthalmic apparatus 1 will be described with reference to Fig. 3. As shown in Fig. 3, the control system of the ophthalmic apparatus 1 is mainly configured with a control unit 100. Note that at least a part of the configuration of the control system may be included in the ophthalmic apparatus 1.

(Control unit 100)
The control unit 100 controls each unit of the ophthalmic apparatus 1. The control unit 100 includes a main control unit 101 and a storage unit 102. The main control unit 101 includes a processor, and executes processing according to a program stored in the storage unit 102, thereby executing control processing of each unit of the ophthalmic apparatus 1.

(Main control unit 101)
The main control unit 101 controls the projection system 10 , the light receiving system 20 , the image processing unit 30 , the image output unit 40 , and the focusing mechanism 52 .

The control of the projection system 10 includes the control of the pattern light generating unit 11. The control of the pattern light generating unit 11 includes the control of the light source 11A and the control of the spatial light modulator 11C. The control of the light source 11A includes switching the light source on and off, and controlling changes in the amount of light from the light source. The control of the spatial light modulator 11C includes spatial amplitude control, phase control, and polarization control of the light from the light source 11A, and temporal amplitude control, phase control, and polarization control of the light from the light source 11A.

When the projection system 10 includes an optical scanner, the main control unit 101 can control the optical scanner. Control of the optical scanner includes control of the scan range (scan start position and scan end position) and scan speed.

The control of the light receiving system 20 includes the control of the image sensor 22. The control of the image sensor 22 includes the control of changing at least one of the exposure timing, sensitivity, and frame rate, and the readout control using the rolling shutter method or the global shutter method.

The control of the image processing unit 30 includes control of the execution of the image processing and the analysis processing. The control of the image output unit 40 includes control of the display of the various information described above.

Control of the focusing mechanism 52 includes control according to the mechanism for focusing the pattern light.

When the focusing mechanism 52 includes a focusing lens, the main control unit 101 identifies focusing control content corresponding to the amount and direction of movement of the focal position of the pattern light identified by the image processing unit 30, and controls a movement mechanism that moves the focusing lens in the optical axis direction based on the identified focusing control content.

When the focusing mechanism 52 includes an objective lens, the main control unit 101 identifies focusing control content corresponding to the amount and direction of movement of the focal position of the pattern light identified by the image processing unit 30, and controls a movement mechanism that moves the device body or the objective lens in the optical axis direction based on the identified focusing control content.

When the focusing mechanism 52 includes a liquid lens or liquid crystal lens, the main control unit 101 identifies focusing control content corresponding to the amount and direction of movement of the focal position of the pattern light identified by the image processing unit 30, and controls the liquid lens or liquid crystal lens based on the identified focusing control content.

As shown in FIG. 3, the memory unit 102 stores control information 102A. The control information 102A includes correspondence information that associates multiple focus control contents (control amount, type of control signal) for the focusing mechanism 52 with multiple combinations of the amount of movement and direction of movement to move the focal position of the pattern light. The main control unit 101 can refer to the correspondence information to identify the focus control contents for the focusing mechanism 52 from the amount of movement and direction of movement to move the focal position of the pattern light identified by the image processing unit 30, and control the focusing mechanism 52 based on the identified focus control contents.

(Memory unit 102)
The storage unit 102 stores various computer programs and data. The computer programs include an arithmetic program and a control program for controlling the ophthalmic apparatus 1. Furthermore, the storage unit 102 stores the control information 102A as described above.

(Operation Unit 110)
The operation unit 110 includes an operation device or an input device. The operation unit 110 includes buttons and switches (e.g., an operation handle, an operation knob, etc.) and operation devices (a mouse, a keyboard, etc.) provided on the ophthalmic apparatus 1. The operation unit 110 may also include any operation device or input device, such as a trackball, an operation panel, a switch, a button, or a dial.

In some embodiments, at least a portion of the image output unit 40 and the operation unit 110 are configured as an integrated unit. As a specific example, the functions of the image output unit 40 and the operation unit 110 are realized by a touch screen.

The projection system 10 is an example of a "projection unit" according to the embodiment. The light receiving system 20 and the control unit 100 that controls the image sensor 22 are an example of an "acquisition unit" according to the embodiment. The image processing unit 30 is an example of a "determination unit" according to the embodiment.

[Action]
Next, the operation of the ophthalmologic apparatus 1 will be described.

Figure 4 shows an explanatory diagram of the process for identifying the focus state according to the embodiment. Figure 4 shows the pattern light and its return light passing through the focusing lens or objective lens, and the received light image RS of the return light superimposed with the projected image PS of the pattern light. In Figure 4, the projected image PS of the pattern light is diagrammatically superimposed on the received light image RS of the return light on the detection surface of the image sensor 22.

As described above, the projection system 10 is capable of projecting pattern light of any projection shape onto the subject's eye E. The light receiving system 20 also receives the return light of the pattern light at the image sensor 22, and the image processing unit 30 can obtain a received light image corresponding to any aperture shape using, for example, a rolling shutter method based on the detection result of the received return light.

For ease of explanation, it is assumed that the pattern light PS is projected onto the subject's eye E from above with respect to the optical axis of the ophthalmic device 1 (objective lens or focusing lens), and the return light RF of the pattern light PS is received from below with respect to the optical axis ((A) and (B) in FIG. 4). Note that the pattern light PS and the return light RF do not have to be symmetrical with respect to the optical axis. The optical path of either the pattern light PS or the return light RF may be arranged on the optical axis. For example, the optical path of the pattern light PS may be arranged on the optical axis, and the optical path of the return light RF may be arranged above or below the optical axis.

When the object (e.g., the fundus of the test eye E) is located on the focal plane at the focal position FS, the position of the projected image PS of the pattern light coincides with the position of the aperture on the light receiving side, and a bright received light image RS with a clear outline is obtained (Figure 4 (A)).

In contrast, when the object is located on the focal plane at a position FS1 away from the focal position FS, the position of the projected image PS of the pattern light and the position of the aperture on the light receiving side are separated, and a dark received light image RS with a blurred outline is obtained (Figure 4B).

Here, the pattern light generating unit 11 moves the projection position of the pattern light on the target object further upward or downward. At this time, even if the target object is located on the focal plane at position FS1, the position of the pattern light projection image PS can be made to coincide with the position of the aperture on the light receiving side. As a result, a bright received light image RS as shown in FIG. 4A is obtained (FIG. 4C).

That is, the luminance distribution of the received light image changes by moving the projection position or projection range of the pattern light and the light receiving side opening relatively in the aperture intersection direction. In this embodiment, the image processing unit 30 identifies the luminance distribution of the acquired received light image in the opening direction, and identifies the focus state of the pattern light based on the identified luminance distribution.

In addition, in (B) and (C) of FIG. 4, the projection position (projection range) of the pattern light is moved in a direction perpendicular to the opening direction, so the brightness of the received light image changes. As a result, it is possible to determine whether the focal position matches the imaging area, but it is not possible to determine to what extent the focal position does not match the imaging area.

Therefore, by intersecting the projection position of the pattern light in a direction different from the direction perpendicular to the opening direction (for example, at 45 degrees), the luminance distribution of the received light image can be changed according to the intersecting direction. This makes it possible to determine not only whether the focal position coincides with the imaging area, but also the amount and direction of movement of the focal position when it does not coincide.

In this embodiment, a pattern light is used in which the projection system shape intersects with the aperture direction at approximately 45 degrees, as follows. This makes it possible to determine, from the received light image obtained by projecting the pattern light once, whether or not the focal position coincides with the imaging area, and, if it does not, to determine the amount and direction of movement of the focal position.

Figures 5A to 5C are schematic diagrams showing the relationship between the projection shape of the pattern light on the detection surface of the image sensor 22 and the aperture shape on the light receiving side, and the received light image. Figure 5A mainly shows the projection shape, aperture shape, and received light image when in focus. Figure 5B shows the projection shape, aperture shape, and received light image when the focal position is on the front side. Figure 5C shows the projection shape, aperture shape, and received light image when the focal position is on the rear side. In Figures 5A to 5C, the projection shape of the pattern light PL intersects with the opening direction of the aperture shape AF at approximately 45 degrees.

As shown in FIG. 5A, when focusing, a received light image Rm with a clear outline is obtained. In the received light image Rm, a bright portion Rp appears in the center of the patterned light PL rather than at the end. The bright portion Rp is depicted at a position corresponding to the optical axis (on the detection surface of the image sensor 22). Therefore, the image processing unit 30 can determine the focused state of the patterned light PL (i.e., whether the focal position of the patterned light PL is the position of the imaging site) by analyzing the received light image Rm to identify the position of the bright portion Rp in the luminance distribution in the opening direction and determining whether the position of the identified bright portion Rp is a predetermined reference position (a position corresponding to the optical axis). In some embodiments, the image processing unit 30 can determine the focused state of the patterned light PL by analyzing the received light image Rm and determining whether the bright portion Rp is identified in the luminance distribution in the opening direction. In this case, it is possible to determine whether the bright portion Rp is identified by comparing the luminance level of the bright portion Rp with a predetermined threshold value.

As shown in FIG. 5B, when the focal position of the pattern light PL is on the front side, a received light image Rm with a blurred outline is acquired. In the received light image Rm, a bright portion Rp1 appears on the edge side of the pattern light PL rather than the center. For example, the bright portion Rp1 is depicted on the left side of the position corresponding to the optical axis (on the detection surface of the image sensor 22). Therefore, the image processing unit 30 analyzes the received light image Rm to identify the position of the bright portion Rp1 in the luminance distribution in the opening direction, and obtains the displacement (amount of deviation, direction of deviation) of the position of the bright portion Rp1 relative to a predetermined reference position (position corresponding to the optical axis). The image processing unit 30 can, for example, use conversion information representing the amount of movement and direction of movement of the focal position corresponding to the displacement obtained in advance to identify the amount of movement and direction of movement of the focal position corresponding to the displacement. The main control unit 101 identifies focus control information from the amount of movement and direction of movement of the identified focal position, and controls the focusing mechanism 52 based on the identified focus control information.

As shown in FIG. 5C, when the focal position of the pattern light PL is on the rear side, a received light image Rm with a blurred outline is acquired. In the received light image Rm, the bright portion Rp2 appears on the edge side rather than the center of the pattern light PL. For example, the bright portion Rp2 is depicted on the right side of the position corresponding to the optical axis (on the detection surface of the image sensor 22). Therefore, the image processing unit 30 analyzes the received light image Rm to identify the position of the bright portion Rp2 in the luminance distribution in the opening direction, and obtains the displacement of the position of the bright portion Rp2 relative to a predetermined reference position (the position corresponding to the optical axis). For example, the image processing unit 30 can identify the amount of movement and the direction of movement of the focal position corresponding to the displacement of the position of the bright portion Rp2 relative to the reference position using conversion information representing the amount of movement and the direction of movement of the focal position corresponding to the displacement obtained in advance. The main control unit 101 identifies focus control information from the amount of movement and the direction of movement of the identified focal position, and controls the focusing mechanism 52 based on the identified focus control information.

Note that Figures 5A to 5C explain the case where bright areas appear when in focus, but the same applies when dark areas appear when in focus.

As described above, the projection system 10 projects pattern light of a projection shape extending at least in the aperture intersecting direction (first direction) onto the subject's eye E, and the image processing unit 30 acquires a received light image corresponding to the aperture shape extending at least in the aperture direction (second direction intersecting the first direction) based on the detection result of the return light of the pattern light from the subject's eye E detected by the light receiving system 20. The image processing unit 30 can identify the focus state of the pattern light based on the luminance distribution of the acquired received light image. In some embodiments, the focus state includes information indicating whether or not the image is in focus, and control content for focusing when the image is not in focus.

Figure 6 shows a flow diagram of an example of the operation of the ophthalmologic apparatus 1 according to the embodiment. The storage unit 102 stores a computer program for implementing the processing shown in Figure 6. The main control unit 101 operates according to this computer program to execute the processing shown in Figure 6.

Here, it is assumed that the alignment of the device optical system with respect to the subject's eye E is completed by an alignment system (not shown), and a fixation target is projected onto the fundus of the subject's eye E so as to guide it to the desired fixation position by a fixation projection system (not shown).

(S1: Projecting pattern light)
First, the main control unit 101 controls the pattern light generating unit 11 to generate pattern light having a projection shape for focus control.

Specifically, the pattern light generating unit 11 generates pattern light that extends at least in a direction intersecting the opening direction of the opening shape (opening crossing direction). The pattern light generated by the pattern light generating unit 11 passes through the smoothing unit 12, the optical system 13, the optical multiplexer/demultiplexer 50, and the optical system 51, and is projected onto the subject's eye E.

(S2: Obtain a received light image)
Next, the main control unit 101 causes the image processing unit 30 to obtain a received light image.

Specifically, the pattern light projected by the projection system 10 onto the subject's eye E is reflected by the subject's eye E. The return light of the pattern light from the subject's eye E passes through the optical system 51, the optical multiplexer/demultiplexer 50, and the optical system 21, and is imaged on the detection surface of the image sensor 22. The main control unit 101 reads out the light reception results of the return light by the image sensor 22 using a rolling shutter method corresponding to a predetermined aperture shape. The image processing unit 30 acquires a light reception image corresponding to the aperture shape based on the read light reception results.

(S3: Analysis)
Next, the main control unit 101 causes the image processing unit 30 to execute a predetermined analysis process on the received light image acquired in step S2.

Specifically, bright and dark areas appear in the acquired light-receiving image as described above. The image processing unit 30 identifies the luminance distribution in the opening direction in the acquired light-receiving image as described above.

(S4: Identify the focus state)
Next, the main control unit 101 causes the image processing unit 30 to specify the focus state of the pattern light.

Specifically, as shown in FIG. 5A, the image processing unit 30 identifies the position of the bright area (or dark area) from the luminance distribution identified in step S3, and determines whether the position of the identified bright area (or dark area) is a predetermined reference position (a position corresponding to the optical axis). When it is determined that the position of the identified bright area (or dark area) is the predetermined reference position, it determines that the focal position of the pattern light is the position of the imaging area.

When it is determined that the position of the identified bright (or dark) area is not a predetermined reference position, the image processing unit 30 obtains the displacement of the position of the bright (or dark) area relative to a predetermined reference position in the luminance distribution, as shown in FIG. 5B or FIG. 5C. Furthermore, the image processing unit 30 determines the amount and direction of movement of the focal position corresponding to the obtained displacement.

In some embodiments, the main control unit 101 causes the image output unit 40 to output (display) information corresponding to the identified focus state or the amount and direction of movement of the identified focus position. Information corresponding to the focus state includes information indicating whether the focus position of the pattern light is at the position of the desired shooting site (focus position), information indicating whether the focus position of the pattern light is in front of or behind the focus position, and the like. For example, the main control unit 101 causes the image output unit 40 to display information (or images, characters, marks, indicators) indicating whether the focus position of the pattern light is at the focus position in green, information indicating that the focus position of the pattern light is in front of the focus position in blue, and information indicating that the focus position of the pattern light is behind the focus position in red. In some embodiments, the main control unit 101 causes the image output unit 40 to display characters, images, and indicators indicating the focus position of the pattern light relative to the focus position.

(S5: Focus control)
Next, the main control unit 101 performs focus control.

Specifically, when it is determined in step S4 that the focal position of the pattern light is the position of the part to be photographed, step S5 is skipped.

On the other hand, when it is determined in step S4 that the focal position of the patterned light is not the position of the part to be photographed, the main control unit 101 identifies focusing control information from the amount and direction of movement of the focal position identified in step S4, and controls the focusing mechanism 52 based on the identified focusing control information.

(S6: Shooting)
Next, the main control unit 101 controls the pattern light generating unit 11 to generate pattern light in a projection shape for photographing.

Specifically, the pattern light generating unit 11 generates pattern light that extends in a direction (e.g., the opening direction) that is approximately parallel to the opening direction of the aperture shape. The pattern light generated by the pattern light generating unit 11 passes through the smoothing unit 12, the optical system 13, the optical multiplexer/demultiplexer 50, and the optical system 51, and is projected onto the subject's eye E. The pattern light projected onto the subject's eye E is reflected by the subject's eye E. The return light of the pattern light from the subject's eye E passes through the optical system 51, the optical multiplexer/demultiplexer 50, and the optical system 21, and is imaged on the detection surface of the image sensor 22. The main control unit 101 reads out the light reception results of the return light by the image sensor 22 using a rolling shutter method corresponding to a predetermined aperture shape. The image processing unit 30 acquires a light reception image corresponding to the aperture shape based on the read light reception results.

Then, the main controller 101 projects a pattern light of the same projection shape as above onto a projection position shifted in a direction perpendicular to the opening direction, and shifts the opening position in the same manner as above to control the reading of the return light reception results by the image sensor 22. This control is repeated multiple times to obtain one frame of a received light image, thereby obtaining a fundus image of the subject's eye E.

This completes the operation of the ophthalmic device 1 (end).

<Modification>
The configuration and control of the ophthalmologic apparatus according to the embodiment are not limited to the above-described aspects. Below, modifications of the embodiment will be described, focusing on the differences from the embodiment.

(First Modification)
In the embodiment, the case where the pattern light generating unit 11 generates pattern light by spatially modulating the light from the light source using a light source and a non-light-emitting device has been described, but the configuration according to the embodiment is not limited to this. In this modification, the pattern light generating unit includes a self-luminous device.

Figure 7 shows a block diagram of an example of the configuration of a pattern light generating unit according to a modified embodiment. The ophthalmic apparatus according to this modified embodiment includes the pattern light generating unit 11a shown in Figure 7 instead of the pattern light generating unit 11.

The pattern light generating unit 11a according to this modified example includes a self-luminous device 120 and an optical system 121. The self-luminous device 120 generates light modulated for each pixel, thereby realizing the function of a pixelated pattern light generator. Examples of the self-luminous device 120 include a cathode-ray tube (CRT), a plasma display (PDP), an organic electro-luminescence (OEL), an LED, an inorganic electro-luminescence (IEL), a vacuum floor display (VFD), and a field emission display (FED).

The self-light-emitting device 120 can be placed at a position that is approximately optically conjugate with the imaging site of the subject's eye E (e.g., the fundus, the anterior segment). The optical system 121 includes a projection lens for projecting the light spatially modulated by the self-light-emitting device 120.

The operation of the ophthalmologic device in this modified example is the same as in the embodiment, so a detailed explanation will be omitted.

(Second Modification)
In the embodiment or its modified example, a case has been described in which the projection shape of the pattern light is a straight line (rectangular shape) that intersects with the opening direction, but the configuration according to the embodiment is not limited to this. In this modified example, the projection shape of the pattern light is a curved line. Also, in this modified example, the projection shape of the pattern light is a shape that intersects with the opening direction multiple times.

Figure 8 shows a schematic diagram of the projection shape of the pattern light according to a modified embodiment. Figure 8 shows a schematic diagram of the relationship between the projection shape of the pattern light on the detection surface of the image sensor 22 and the aperture shape on the light receiving side when in focus, when the focal position is on the front side, and when the focal position is on the rear side.

As shown in FIG. 8, when in focus, a received light image with clear contours is obtained. In the received light image, bright and dark areas appear alternately because the pattern light PL1 intersects with the aperture shape AF multiple times. Therefore, the image processing unit 30 analyzes the received light image to identify the positions of the bright and dark areas that appear alternately in the luminance distribution in the aperture direction, and determines whether any of the identified bright areas is a predetermined reference position (a position corresponding to the optical axis), thereby making it possible to determine the focused state of the pattern light PL1 (i.e., whether the focal position of the pattern light PL1 is the position of the photographed area).

In addition, in this modified example, by determining whether the positions of multiple bright areas are at a predetermined reference position, it becomes possible to determine the focus state of the pattern light PL1 with higher accuracy.

Similarly, when the focal position of the pattern light PL2 is on the front side or when the focal position of the pattern light PL3 is on the rear side, a received light image with a blurred outline is acquired. In the received light image, the pattern light PL2 and PL3 intersect with the aperture shape AF multiple times, so that bright and dark areas appear alternately. Therefore, the image processing unit 30 analyzes the received light image to identify the positions of the bright and dark areas that appear alternately in the luminance distribution in the aperture direction, and determines the displacement (amount of deviation, direction of deviation) of any of the positions of the multiple bright areas relative to a predetermined reference position (position corresponding to the optical axis). For example, the image processing unit 30 can specify the amount of movement and direction of movement of the focal position corresponding to the displacement of the position of the bright area relative to the reference position using predetermined conversion information, as described above. The main control unit 101 specifies focus control information from the amount of movement and direction of movement of the specified focal position, and controls the focusing mechanism 52 based on the specified focus control information.

In addition, in this modified example, the displacement of the positions of multiple bright areas relative to a predetermined reference position is calculated, and the amount and direction of movement of the focal position corresponding to the calculated displacements are identified, making it possible to adjust the focal positions of the patterned lights PL2 and PL3 with higher accuracy.

Note that Figure 8 describes the case where bright areas appear when in focus, but the same applies when dark areas appear when in focus.

(Third Modification)
In the second modified example, the projection shape of the pattern light is described as a shape that intersects with the opening direction multiple times, but the configuration according to the embodiment is not limited to this. For example, the projection shape of the pattern light may be a shape that is highly sensitive to determining the focus state. An example of a shape that is highly sensitive to determining the focus state is a shape that has a portion that is approximately parallel to the opening direction at a position corresponding to the optical axis.

Figure 9 shows a schematic diagram of the projection shape of the pattern light according to a modified embodiment. Figure 9 shows a schematic diagram of the relationship between the projection shape of the pattern light on the detection surface of the image sensor 22 and the aperture shape on the light receiving side when in focus, when the focal position is on the front side, and when the focal position is on the rear side.

As shown in FIG. 9, when focusing, a received light image with a clear outline is obtained. At the position corresponding to the optical axis on the detection surface of the image sensor 22 (reference position during focusing control), the pattern light PL11 having a shape having a portion approximately parallel to the opening direction of the aperture shape AF is projected, so that bright areas appear in the center rather than the ends in the received light image. Therefore, the image processing unit 30 can analyze the received light image to identify the position of the bright area in the luminance distribution in the opening direction, and determine whether the position of the identified bright area is a predetermined reference position (position corresponding to the optical axis), thereby determining the focused state of the pattern light PL11 (i.e., whether the focal position of the pattern light PL1 is the position of the photographed part).

Similarly, when the focal position of the pattern light PL12 is on the front side or when the focal position of the pattern light PL13 is on the rear side, a received light image with a blurred outline is acquired. In the received light image, dark areas tend to appear overall. Therefore, the image processing unit 30 analyzes the received light image to identify the position of the bright area in the luminance distribution in the opening direction, and obtains the displacement (amount of deviation, direction of deviation) of the position of the bright area relative to a predetermined reference position (position corresponding to the optical axis). For example, the image processing unit 30 can use predetermined conversion information in the same manner as above to identify the amount of movement and direction of movement of the focal position corresponding to the displacement of the position of the bright area relative to the reference position. The main control unit 101 identifies focus control information from the identified amount of movement and direction of movement of the focal position, and controls the focusing mechanism 52 based on the identified focus control information.

Note that Figure 9 describes the case where bright areas appear when in focus, but the same applies when dark areas appear when in focus.

(Fourth Modification)
In the embodiment or its modified example, a case where the projection shape of the pattern light intersects with the aperture shape on the light receiving side has been described, but the configuration according to the embodiment is not limited to this. For example, the projection shape of the pattern light may be a shape that extends in a direction substantially parallel to the aperture direction.

Figures 10A to 10C are schematic diagrams showing the relationship between the projection shape of the pattern light on the detection surface of the image sensor 22 in a modified embodiment and the aperture shape on the light receiving side. Figure 10A mainly shows the projection shape and aperture shape when in focus. Figure 10B shows the projection shape and aperture shape when the focal position is on the front side. Figure 10C shows the projection shape and aperture shape when the focal position is on the rear side. In Figures 10A to 10C, the projection shape of the pattern light PL is assumed to be parallel to the opening direction of the aperture shape AF.

As shown in FIG. 10A, when in focus, a received light image with clear contours is obtained. The received light image is bright overall. Therefore, the image processing unit 30 can determine the focused state of the patterned light PL (i.e., whether the focal position of the patterned light PL is the position of the imaging site) by analyzing the received light image and determining whether a bright area has been identified in the luminance distribution in the opening direction. In this case, it is possible to determine whether a bright area has been identified by comparing the luminance level of the bright area with a predetermined threshold value.

As shown in FIG. 10B or FIG. 10C, when the focal position of the patterned light PL is on the front or rear side, a received light image with blurred contours and overall darkness is obtained. Therefore, the image processing unit 30 can determine the focus state of the patterned light PL (i.e., whether the focal position of the patterned light PL is at the position of the imaging site) by analyzing the received light image and determining whether a bright area has been identified in the luminance distribution in the opening direction.

When no bright area is identified, the main controller 101 relatively moves the projection position of the pattern light and the position of the aperture shape in a direction perpendicular to the aperture direction. Specifically, the main controller 101 controls the pattern light generator 11 (11a) to generate pattern light so that the projection position on the imaging area shifts. Alternatively, the main controller 101 changes the aperture position by controlling the timing of reading out the reception result of the return light of the pattern light by the image sensor 22, and causes the image processor 30 to acquire a received light image corresponding to the changed aperture position.

The image processing unit 30 identifies the luminance level in the luminance distribution of two or more received light images obtained by relatively moving the projection position of the pattern light and the position of the aperture shape, and determines the difference from a predetermined threshold level. For example, the image processing unit 30 can use conversion information representing the amount of movement and the direction of movement of the focal position corresponding to the difference obtained in advance to identify the amount of movement and the direction of movement of the focal position corresponding to the difference. The main control unit 101 identifies focus control information from the identified amount of movement and the direction of movement of the focal position, and controls the focusing mechanism 52 based on the identified focus control information.

Note that Figures 10A to 10C explain the case where bright areas appear when in focus, but the same applies when dark areas appear when in focus.

In addition, in Figures 10A to 10C, the received light image may be acquired using a global shutter method. In this case, it is not necessary to project the pattern light onto the subject's eye multiple times.

Figure 11 shows a flow diagram of an example of the operation of the ophthalmologic apparatus 1 according to a modified embodiment. The storage unit 102 stores a computer program for implementing the process shown in Figure 11. The main control unit 101 operates according to this computer program to execute the process shown in Figure 11.

Here, it is assumed that the alignment of the device optical system with respect to the subject's eye E is completed by an alignment system (not shown), and that a fixation target is projected onto the fundus of the subject's eye E so as to guide it to the desired fixation position by a fixation projection system (not shown).

(S11: Projecting pattern light)
First, the main control unit 101 controls the pattern light generating unit 11 to generate pattern light having a projection shape for focus control.

Specifically, the pattern light generating unit 11 generates pattern light that extends in a direction approximately parallel to the opening direction of the opening shape. The pattern light generated by the pattern light generating unit 11 passes through the smoothing unit 12, the optical system 13, the optical multiplexer/demultiplexer 50, and the optical system 51, and is projected onto the subject's eye E.

(S12: Acquire received light image)
Next, the main control unit 101 causes the image processing unit 30 to obtain a received light image, similarly to step S2.

(S13: Analysis)
Next, the main control unit 101 causes the image processing unit 30 to execute a predetermined analysis process on the received-light image acquired in step S12, similarly to step S3.

(S14: Identify the focus state)
Next, the main control unit 101 causes the image processing unit 30 to specify the focus state of the pattern light.

Specifically, as shown in FIG. 10A, the image processing unit 30 identifies a luminance level from the luminance distribution identified in step S13, and determines whether the received light image is bright by comparing the identified luminance level with a predetermined threshold value.

(S15: Next?)
If it is determined in step S14 that the received light image is bright, it is determined that the focal position of the patterned light is the position of the photographing part (S15: N), and the operation of the ophthalmologic apparatus 1 proceeds to step S16.

When it is determined that the received light image is not bright, it is determined that the focal position of the patterned light is not the position of the photographed part (S15: Y), and the operation of the ophthalmic device 1 proceeds to step S11. In step S11, the main controller 101 controls the patterned light generator 11 (11a) to generate patterned light so that the projection position on the photographed part is shifted. Alternatively, in step S12 following step S11, the main controller 101 changes the aperture position by controlling the readout timing of the reception result of the return light of the patterned light by the image sensor 22, and causes the image processor 30 to acquire the received light image corresponding to the changed aperture position.

(S16: Focus control)
Next, the main control unit 101 performs focus control.

Specifically, when it is determined in step S14 that the focal position of the pattern light is the position of the part to be photographed, step S16 is skipped.

On the other hand, when it is determined in step S14 that the focal position of the pattern light is not the position of the part to be photographed, the main controller 101 identifies the luminance level in the luminance distribution of two or more received light images obtained by relatively moving the projection position of the pattern light and the position of the aperture shape as described above, and obtains the difference from a predetermined threshold level. The image processor 30 identifies the amount of movement and the direction of movement of the focal position corresponding to the obtained difference, for example, using predetermined conversion information. The main controller 101 identifies focus control information from the identified amount of movement and direction of movement of the focal position, and controls the focusing mechanism 52 based on the identified focus control information.

(S17: Shooting)
Next, the main controller 101 controls the pattern light generator 11 to generate pattern light having a projection shape for photography, as in step S6, and obtains an image of the fundus of the subject's eye E.

This completes the operation of the ophthalmic device 1 (end).

In this modified example, in step S11, the projection shape of the pattern light is described as a shape that extends in a direction approximately parallel to the opening direction, but this is not limited to this. For example, the projection shape of the pattern light may be a square shape, a circle shape, or a bright spot. In other words, by analyzing the image of the test eye E obtained while sequentially changing the projection shape of the pattern light (projection position and projection range on the test eye E) over time, it is possible to identify the focus state of the pattern light (or the amount and direction of movement to be made to the focus position).

As described above, the projection system 10 projects pattern light of a projection shape extending at least in the aperture direction onto the subject's eye E, and the image processing unit 30 acquires a received light image corresponding to the aperture shape extending in a predetermined aperture direction based on the detection result of the return light of the pattern light from the subject's eye E detected by the light receiving system 20. The image processing unit 30 can identify the focusing state of the pattern light based on the luminance distribution of one or more acquired received light images. In some embodiments, the image processing unit 30 identifies the control content for focusing based on the luminance distribution of two or more received light images acquired by shifting the projection position of the pattern light or the aperture position.

[Action and Effects]
The operation and effects of the ophthalmic apparatus and the control method thereof according to the embodiment will be described.

An ophthalmic device (1) according to some embodiments includes a projection unit (projection system 10), an acquisition unit (control unit 100 that controls the light receiving system 20 and the image sensor 22), and an identification unit (image processing unit 30). The projection unit projects pattern light of a projection shape extending at least in a first direction onto the subject's eye (E). The acquisition unit acquires a received light image corresponding to an aperture shape extending at least in a second direction intersecting the first direction, based on the detection result of the return light of the pattern light from the subject's eye. The identification unit identifies the focus state of the pattern light based on the luminance distribution of the received light image.

With this configuration, a received light image corresponding to an opening shape extending in at least a second direction intersecting the first direction is obtained based on the result of receiving the return light of the pattern light having a projection shape extending in at least a first direction. This makes it possible to obtain a received light image whose luminance distribution changes according to the focusing state of the pattern light. Therefore, with a simple configuration, it becomes possible to identify the optimal focusing state with good reproducibility.

An ophthalmic device (1) according to some embodiments includes a projection unit (projection system 10), an acquisition unit (a control unit 100 that controls a light receiving system 20 and an image sensor 22), and an identification unit (an image processing unit 30). The projection unit projects pattern light of a projection shape extending at least in a first direction onto the subject's eye (E). The acquisition unit acquires a received light image corresponding to an aperture shape extending at least in the first direction based on a detection result of return light of the pattern light from the subject's eye. The identification unit identifies the focus state of the pattern light based on a luminance distribution in a second direction intersecting the first direction in one or more received light images acquired by the acquisition unit.

With this configuration, a received light image corresponding to an opening shape extending at least in the first direction is acquired based on the result of receiving the return light of the pattern light having a projection shape extending at least in the first direction, and the focusing state of the pattern light is identified based on the luminance distribution in a second direction intersecting the first direction in the acquired one or more received light images. This makes it possible to reproducibly identify the optimal focusing state with a simple configuration.

In some embodiments, the determination unit includes a control unit (110) that determines the focus control content of the pattern light based on the luminance distribution in the second direction in the received light image, and performs focus control of the pattern light based on the determined focus control content.

This configuration makes it possible to control the focus of the pattern light with a simple structure.

In some embodiments, the control unit performs focus control so that the bright or dark area moves to a predetermined position (a position corresponding to the optical axis on the detection surface of the image sensor 22).

With this configuration, focusing control can be performed based on the bright or dark areas that appear in the received light image, making it possible to control the focusing of the pattern light with a simple configuration.

Some embodiments include a focusing mechanism (52) disposed in the optical path of the pattern light and the return light, and the control unit controls the focusing mechanism based on the identified focusing control content.

This configuration makes it possible to control the focus of the pattern light with a simple structure.

In some embodiments, the projection unit includes a projector that outputs a pattern of light whose projection shape can be changed.

With this configuration, the projection shape can be easily changed to output pattern light, making it possible to provide an ophthalmic device with a simple configuration that can accurately identify the optimal focus state.

In some embodiments, the projection unit outputs pattern light of a first projection shape for identifying the focus state, and after focusing control of the pattern light, outputs pattern light of a second projection shape different from the first projection shape, and the acquisition unit acquires the received light image based on the detection result of the return light of the pattern light of the second projection shape.

With this configuration, it is possible to provide an ophthalmic device that can, with a simple configuration, identify the optimal focus state with good reproducibility, perform focus control of the pattern light, and after focus control, output a new pattern light to obtain an image of the subject's eye.

In some embodiments, the acquisition unit includes an image sensor (22) that detects the returning light, and acquires the received light image using a rolling shutter method.

This configuration makes it possible to provide an ophthalmic device that is simple in configuration and capable of reproducibly identifying the optimal focus state.

A control method for an ophthalmic device (1) according to some embodiments includes a projection step of projecting pattern light having a projection shape extending at least in a first direction onto a test eye (E), an acquisition step of acquiring a received light image corresponding to an aperture shape extending at least in a second direction intersecting the first direction based on a detection result of return light of the pattern light from the test eye, and an identification step of identifying a focus state of the pattern light based on a luminance distribution of the received light image.

According to this method, a received light image corresponding to an opening shape extending in at least a second direction intersecting the first direction is obtained based on the result of receiving the return light of a pattern light having a projection shape extending in at least a first direction. This makes it possible to obtain a received light image whose luminance distribution changes according to the focusing state of the pattern light. Therefore, it becomes possible to identify the optimal focusing state with good reproducibility with a simple configuration.

A control method for an ophthalmic device (1) according to some embodiments includes a projection step of projecting pattern light having a projection shape extending at least in a first direction onto a test eye (E), an acquisition step of acquiring a received light image corresponding to an aperture shape extending at least in the first direction based on a detection result of return light of the pattern light from the test eye, and an identification step of identifying a focus state of the pattern light based on a luminance distribution in a second direction intersecting the first direction in one or more received light images acquired in the acquisition step.

According to this method, a received light image corresponding to an opening shape extending in at least a first direction is acquired based on the result of receiving the return light of the pattern light having a projection shape extending in at least a first direction, and the focusing state of the pattern light is identified based on the luminance distribution in a second direction intersecting the first direction in the acquired one or more received light images. This makes it possible to reproducibly identify the optimal focusing state with a simple configuration.

In some embodiments, the identification step includes a control step of identifying focus control content of the pattern light based on the luminance distribution in the second direction in the received light image, and performing focus control of the pattern light based on the identified focus control content.

This method makes it possible to control the focus of the pattern light with a simple configuration.

In some embodiments, the projection step includes a first projection step of outputting a pattern light of a first projection shape for identifying a focus state, and a second projection step of outputting a pattern light of a second projection shape different from the first projection shape after focusing control of the pattern light, and the acquisition step includes a first acquisition step of acquiring a received light image corresponding to the opening shape based on the detection result of the return light of the pattern light of the first projection shape projected in the first projection step, and a second acquisition step of acquiring a received light image based on the detection result of the return light of the pattern light of the second projection shape projected in the second projection step.

This method makes it possible to reproducibly identify the optimal focus state with a simple configuration, perform focus control of the pattern light, and after focus control, output a new pattern light to obtain an image of the test eye.

In some embodiments, the acquisition step acquires the received light image using a rolling shutter method based on the detection result of the return light.

This method makes it possible to determine the optimal focus state with good reproducibility using a simple configuration.

The above-described embodiment or its modified examples are merely examples of how to implement this invention. Anyone who wishes to implement this invention may make any modifications, omissions, additions, etc. within the scope of the gist of this invention.

In the above embodiment or its modified example, the ophthalmic device may have any function that can be used in the field of ophthalmology, such as an axial length measurement function, an intraocular pressure measurement function, a fundus photography function, an optical coherence tomography (OCT) function, and an ultrasound examination function. The axial length measurement function may be realized by an optical coherence tomograph or the like. The axial length measurement function may be performed by projecting light onto the subject's eye and detecting the return light from the fundus while adjusting the position of the optical system in the Z direction (front-back direction) relative to the subject's eye, thereby measuring the axial length of the subject's eye. The intraocular pressure measurement function is realized by a tonometer or the like. The fundus photography function is realized by a fundus camera or a scanning ophthalmoscope (SLO) or the like. The OCT function is realized by an optical coherence tomograph or the like. The ultrasound examination function is realized by an ultrasound diagnostic device or the like. The present invention may also be applied to a device (multifunction device) equipped with two or more of these functions.

In some embodiments, a program is provided for causing a computer to execute the above-mentioned method for controlling an ophthalmic device. Such a program can be stored in any recording medium that can be read by a computer. Examples of the recording medium that can be used include semiconductor memory, optical disks, magneto-optical disks (CD-ROM/DVD-RAM/DVD-ROM/MO, etc.), and magnetic storage media (hard disks/floppy disks/ZIP, etc.). It is also possible to transmit and receive the program via a network such as the Internet or a LAN.

1 Ophthalmic apparatus 10 Projection system 11, 11a Pattern light generating unit 11A Light source 11C Spatial light modulator 12 Smoothing unit 11B, 13, 21, 51, 121 Optical system 20 Light receiving system 22 Image sensor 30 Image processing unit 40 Image output unit 50 Optical multiplexer/demultiplexer 52 Focusing mechanism 100 Control unit 101 Main control unit 102 Storage unit 102A Control information 110 Operation unit 120 Self-luminous device E Subject's eye

Claims (6)

An ophthalmologic apparatus that projects a pattern light having a projection shape corresponding to a shape of an opening on a light receiving side onto an eye to be examined, and reads out a reception result of the return light from the image sensor by a rolling shutter method corresponding to the shape of the opening on a detection surface of an image sensor that receives return light of the pattern light from the eye to be examined,
a projection unit that projects the pattern light having a projection shape extending in a first direction onto the subject's eye;
an acquisition unit that acquires a received light image corresponding to a shape of the opening extending in the first direction based on a detection result of the return light;
a determination unit that determines a focus state of the pattern light based on a luminance distribution in a second direction intersecting the first direction in two or more received light images acquired by the acquisition unit;
Including,
the projection unit projects the pattern light so as to be projected onto a projection position that is moved relatively in the second direction with respect to a position of the opening on the detection surface,
an ophthalmic device, wherein the identification unit identifies a luminance level in a luminance distribution of the two or more received light images obtained by moving the projection position relatively to the position of the opening on the detection surface , calculates a difference between the identified luminance level and a predetermined threshold level, and uses predetermined conversion information to identify, as the in-focus state, a movement amount and a movement direction of the focus position corresponding to the calculated difference. the specifying unit specifies a focus control content of the pattern light based on a luminance distribution in the second direction in the received-light image,
The ophthalmic apparatus according to claim 1 , further comprising a control unit that performs focus control of the pattern light based on the specified focus control content. a focusing mechanism disposed in an optical path of the pattern light and the return light,
The ophthalmologic apparatus according to claim 2 , wherein the control unit controls the focusing mechanism based on the specified focusing control content. The ophthalmologic apparatus according to any one of claims 1 to 3 , wherein the projection unit includes a projector that outputs a pattern light whose projection shape is changeable. A method for controlling an ophthalmic device, comprising: projecting a pattern light having a projection shape corresponding to a shape of an opening on a light receiving side onto a test eye; and reading out a reception result of the return light from an image sensor by a rolling shutter method in accordance with a shape of the opening on a detection surface of an image sensor that receives return light of the pattern light from the test eye, the method comprising:
a projection step of projecting the pattern light having a projection shape extending in a first direction onto the subject's eye;
an acquisition step of acquiring a received light image corresponding to a shape of the opening extending in the first direction based on a detection result of the return light;
a specifying step of specifying a focusing state of the pattern light based on a luminance distribution in a second direction intersecting the first direction in two or more received light images acquired in the acquiring step;
Including,
the projection step projects the pattern light so as to be projected onto a projection position that is moved relatively in the second direction with respect to a position of the opening on the detection surface;
The identification step includes identifying a luminance level in a luminance distribution of the two or more received light images obtained by moving the projection position relatively to the position of the opening on the detection surface , determining a difference between the identified luminance level and a predetermined threshold level, and using predetermined conversion information, identifying the amount and direction of movement of the focus position corresponding to the determined difference as the focus state. the specifying step specifies a focus control content of the pattern light based on a luminance distribution in the second direction in the received light image,
The control method for an ophthalmic apparatus according to claim 5 , further comprising a control step of performing focus control of the pattern light based on the specified focus control content.

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