Fundus imaging device

Abstract

To provide a fundus imaging device that can reduce the size of the device while suppressing thermal changes in the optical system. [Solution] The system comprises a base, a display unit, an imaging optical system for capturing at least a color image as a frontal image of the fundus of the eye under examination, an OCT optical system for acquiring OCT data of the fundus of the eye under examination, a control unit that performs at least the following: imaging control of the imaging optical system and the OCT optical system, display control processing of the OCT image based on the color image and OCT data, and analysis processing of the OCT data, and an imaging unit that houses the imaging optical system, the OCT optical system, and the control unit inside and is placed on the base, wherein within the imaging unit, the control unit is positioned above the imaging optical system and the OCT optical system.

Description

Technical Field

[0001] The present disclosure relates to a fundus imaging device that images the fundus of an eye to be examined.

Background Art

[0002] As a fundus imaging device for imaging the fundus of an eye to be examined, a composite device capable of imaging a frontal fundus image with a color image and an OCT image is known (see Patent Document 1). Generally, such a composite device is a separable device in which a device body including a photographing unit (also referred to as a head unit) incorporating various optical systems and an external control device connected to the device body are separated, and the external control device functions as a photographing control unit, a display control unit, an analysis processing unit, and the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, such composite devices have been introduced not only in ophthalmic medical facilities but also in various facilities such as, for example, medical examination facilities and optical stores. To create a device that can be easily installed in various facilities, it is conceivable to integrate the control device into the main body, similar to other ophthalmic examination devices such as autorefractors, while further reducing the installation area. Therefore, when considering placing the control device within the imaging unit that houses various optical systems to reduce the installation area, the effect of heat generated by the control device on the optical system became a problem. In other words, in such a composite device, a certain amount of space must be secured within the imaging unit for the optical system. Furthermore, the amount of data processed by the control device for imaging control, display control, and analysis processing is significantly larger than that of other ophthalmic examination devices. For this reason, in such a composite device, if the optical system and control device are placed within the same imaging unit, it is necessary to sufficiently suppress the effect of heat generated by the control device on the optical system.

[0005] This disclosure is based on the problems of the prior art described above, and aims to provide a fundus imaging device that can reduce the size of the device while suppressing thermal changes in the optical system. [Means for solving the problem]

[0006] The fundus imaging apparatus of the present disclosure comprises a base, a display unit, an imaging optical system for capturing at least a color image as a frontal image of the fundus of the eye under examination, an OCT optical system for acquiring OCT data of the fundus of the eye under examination, a control unit that performs at least the following: imaging control of the imaging optical system and the OCT optical system, display control processing of the OCT image based on the color image and the OCT data, and analysis processing of the OCT data, and an imaging unit that houses the imaging optical system, the OCT optical system, and the control unit inside and is arranged on the base, wherein the control unit is arranged above the imaging optical system and the OCT optical system within the imaging unit. [Brief explanation of the drawing]

[0007] [Figure 1] This is a right side view of a fundus imaging device. [Figure 2] This is a left side view of a fundus imaging device. [Figure 3] These are schematic diagrams of various optical systems. [Figure 4] This is a diagram showing the configuration of the imaging optical system. [Figure 5] This is a diagram showing the configuration of the control unit. [Figure 6] This is a front view of a fundus imaging device. [Modes for carrying out the invention]

[0008] [overview] Embodiments of the fundus imaging apparatus relating to this disclosure are described below. Each embodiment may be applied to some or all of the other embodiments. For example, the items classified in <> below may be used independently or in conjunction with each other.

[0009] The fundus imaging device of this embodiment has the configuration of a so-called fundus camera. The fundus imaging device uses the imaging optical system described later to capture a frontal image of the fundus in color and displays the frontal image on the display unit. Furthermore, the fundus imaging device of this embodiment has the configuration of a so-called optical coherence tomography (OCT). The fundus imaging device also functions as an information analysis device that analyzes OCT data of tissue (for example, the fundus) captured using the OCT optical system described later, and generates OCT images (for example, tomographic images, motion contrast images, etc.) which are the results of the OCT data analysis and displays them on the display unit.

[0010] The fundus imaging apparatus of this embodiment includes an imaging optical system (for example, an imaging optical system 200). For example, all or part of the imaging optical system is housed in the imaging unit described later. The fundus imaging apparatus of this embodiment also includes an OCT optical system (for example, an OCT optical system 201). For example, all or part of the OCT optical system is housed in the imaging unit described later.

[0011] <Filming optics> The imaging optical system is an optical system that at least captures a color image as a frontal image of the fundus of the eye to be examined. The imaging optical system includes an irradiation optical system that irradiates the fundus of the eye to be examined with illumination light using visible light, and a light-receiving optical system that includes a light-receiving element that receives the reflected light of the fundus of the illumination light. For example, for the eye to be examined, the illumination light is guided through an objective optical system. Also, the imaging optical system forms an irradiation region and a light-receiving region of the imaging light on the pupil of the eye to be examined. The imaging optical system captures a frontal image of the fundus of the eye to be examined by transmitting and receiving the imaging light through the irradiation region and the light-receiving region. The imaging optical system may also serve as a fundus observation optical system for acquiring a fundus observation image.

[0012] <OCT optical system> The OCT optical system is an optical system for acquiring OCT data of the fundus by utilizing the interference between the measurement light and the reference light irradiated to the eye to be examined. The OCT optical system accommodated in the imaging unit may at least include a measurement optical system that guides the measurement light guided from an optical splitter to the fundus of the eye to be examined. For example, for the eye to be examined, the measurement light is guided through an objective optical system. Additionally, the OCT optical system accommodated in the imaging unit may include a detector that detects the interference light between the return light of the measurement light and the reference light.

[0013] For example, the OCT optical system may be based on time-domain OCT (TD-OCT). Also, for example, the OCT optical system may be based on a Fourier-domain OCT optical system. As the Fourier-domain OCT optical system, spectral-domain OCT (SD-OCT), swept-source OCT (SS-OCT), etc. can be adopted. In the case of SD-OCT, a low-coherence light source (broadband light source) is used as the measurement light source, and a spectroscopic optical system (spectrometer) that splits the interference light into each frequency component (each wavelength component) is provided near the light-receiving element in the optical path of the interference light. In the case of SS-OCT, a wavelength-scanning light source (wavelength-variable light source) that changes the emission wavelength at high speed over time is used as the measurement light source.

[0014] Furthermore, the technology of this embodiment can also be applied to intensity OCT for detecting the reflectance intensity of the eye under examination, OCT angiography (e.g., Doppler OCT) for detecting motion contrast data of the eye under examination, polarization-sensitive OCT (PS-OCT), multifunction OCT which combines intensity OCT and PS-OCT, and the like.

[0015] In the above-described imaging optical system and OCT optical system, at least some components may be shared. For example, the objective optical system for guiding the illumination light of the imaging optical system to the fundus of the eye under examination and the objective optical system for guiding the measurement light of the OCT optical system may be shared. In this case, an optical path coupling member (e.g., a beam splitter 221) may be provided to couple the optical path of the imaging optical system and the optical path of the OCT optical system, and the objective optical system is positioned between the eye under examination and the optical path coupling member. As the optical path coupling member, a beam splitter, a half mirror, a dichroic mirror, etc., can be used.

[0016] <Department Head> The control unit (for example, control unit 100) performs imaging control of the imaging optical system and the OCT optical system. The control unit also performs display control processing for the color image captured using the imaging optical system and the OCT image based on the OCT data acquired using the OCT optical system. The control unit also performs analysis processing of the OCT data. The analysis processing may include at least one of the following: layer detection processing (segmentation processing) of the OCT image, tissue thickness analysis processing, and tissue density analysis processing. The control unit may also perform controls other than these imaging control, display control processing, and analysis processing.

[0017] The fundus imaging device of this embodiment includes a display unit (for example, display unit 125), a base (for example, base 7), and an imaging unit (for example, imaging unit 3) disposed on the base. The display unit may be provided on the device main body or may be connected to the device main body by wire or wirelessly. The imaging unit houses an imaging optical system, an OCT optical system, and a control unit inside. In the imaging unit, the imaging optical system and the OCT optical system may be protected by an enclosure that individually covers each optical system or an enclosure that entirely covers each optical system. By disposing the control unit inside the imaging unit, an external control device is not required, and a stand-alone device capable of performing imaging, display, analysis, etc. can be realized in a compact manner. The fundus imaging device of this embodiment may further have a driving unit (for example, driving unit 8) that moves the imaging unit with respect to the base.

[0018] In the fundus imaging device, the control unit is disposed above the imaging optical system and the OCT optical system. For example, when the imaging optical system and the OCT optical system are arranged in parallel, the control unit may be disposed above the imaging optical system or the OCT optical system. Also, for example, when one of the imaging optical system and the OCT optical system is stacked on the other, the control unit may be disposed further above the optical system disposed on top. Note that the upper part of the imaging optical system and the OCT optical system only needs to be the upper part in terms of space. For example, it may be the upper part that exceeds at least a part within the installation surface of the imaging optical system and the OCT optical system. Also, for example, it may be the upper part within the installation surface of the imaging optical system and the OCT optical system. However, if the control unit is disposed above the optical system beyond at least a part within the installation surface of each optical system, the lateral width of the imaging unit will become large. Therefore, in order to save space in the imaging unit, it is preferable to dispose the control unit above the optical system within the installation surface of each optical system.

[0019] Even when the control unit and the optical system are arranged inside the imaging unit, by arranging the control unit above the optical system, thermal changes in the optical system are more likely to be suppressed. The processes such as imaging, display, and analysis performed by the control unit are high-load. If the control unit generates heat at a high temperature (for example, 50 to 85 °C), there is a possibility of causing thermal changes such as the expansion of components holding each member of the optical system. However, since the hot air heated by the control unit is less likely to reach the optical system, displacement of the optical axis and changes in the total optical path length due to thermal changes are suppressed.

[0020] In the fundus imaging device, the control unit may be arranged above the optical axis of the objective optical system for guiding light to the fundus, between the examined eye and the optical path coupling member. In this case, the hot air generated by the control unit rises, and at least the possibility that the objective optical system is affected by thermal changes can be reduced.

[0021] In the fundus imaging device, the control unit may be arranged above the enclosure covering the imaging optical system and the OCT optical system. Since the control unit is arranged above all the members constituting the imaging optical system and the OCT optical system, each optical system is less likely to be affected by thermal changes.

[0022] In the fundus imaging device of the present embodiment, a detector included in the OCT optical system may be arranged inside the imaging unit. As an example, in SD-OCT, a spectrometer may be used as the detector. The spectrometer includes at least a plurality of optical elements including a grating that disperses the interference light between the measurement light and the reference light and a light receiving element that detects the dispersed interference light, and a mount unit that holds the optical elements. For example, when the detector is housed in the base, it is necessary to consider the movement of the imaging unit in the wiring between the control unit and the detector, and the configuration is likely to become complicated. On the other hand, when the detector is arranged inside the imaging unit together with the control unit instead of the base, the configuration such as the wiring for electrically connecting the detector and the control unit is likely to be simplified. Furthermore, when a display unit is attached to the imaging unit, the configuration such as the wiring for electrically connecting the control unit and the display unit is also likely to be simplified.

[0023] Furthermore, if the detector of the OCT optical system is located within the imaging unit rather than on the base, the base can be made more space-efficient, thus reducing the overall installation area of ​​the device. The detector's position within the imaging unit is below the control unit, which is a heat source. Therefore, even if the detector is located within the imaging unit together with the control unit, heat from the control unit is less likely to reach the detector.

[0024] In the fundus imaging apparatus of this embodiment, the imaging unit has an exhaust port (e.g., exhaust port 5) for releasing air. Furthermore, within the imaging unit, a blower mechanism (e.g., fan 6) for creating airflow is provided on the side of the control unit. Air flows through the imaging unit by the blower mechanism and is released outside the imaging unit through the exhaust port. A fan, blower, etc., may be used as the blower mechanism. This allows for efficient discharge of the heated air generated by the control unit.

[0025] The air blowing mechanism may consist of one or more components. For example, the air blowing mechanism may consist of multiple air blowing mechanisms arranged in parallel on the side of the control unit. As an example, the air blowing mechanisms may be arranged in parallel along the longitudinal direction of the control unit on the side of the control unit. In this case, since the air blowing mechanisms are arranged along the control unit, all the blown air can be directed towards the control unit. Therefore, the cooling efficiency is increased.

[0026] Furthermore, if the imaging unit is equipped with an exhaust port and a blower mechanism is located on the side of the control unit, the exhaust port will be positioned at the same height as the blower mechanism by placing the exhaust port at the same height as the control unit. As a result, the circulation of hot air within the imaging unit is suppressed, and thermal changes in the optical system can be further suppressed.

[0027] [Examples] An embodiment of the fundus imaging device according to this embodiment will be described. The fundus imaging device 1 captures a color frontal image of the fundus Er of the eye under examination E. The fundus imaging device 1 also captures an OCT image of the fundus Er of the eye under examination E. The OCT image may be a tomographic image, a frontal image (EnFace image), a motion contrast image, etc.

[0028] Figures 1 and 2 are external views of the fundus imaging device 1. Figure 1 is a right side view of the fundus imaging device 1. Figure 2 is a left side view of the fundus imaging device 1. In this embodiment, the side of the fundus imaging device 1 where the face support part 9 is located is considered the front, and the opposite side is considered the back. With respect to the front of the fundus imaging device 1, the left-right direction is the X direction, the up-down direction is the Y direction, and the front-back direction is the Z direction.

[0029] The fundus imaging device 1 includes a base 7, an imaging unit 3, a drive unit 8, a face support unit 9, an exhaust port 5, an operation unit 30, a display unit 125, a control unit 100, etc. The base 7 supports the imaging unit 3. The base 7 also supports the face support unit 9. The imaging unit 3 is the examination unit. The imaging unit 3 is covered by a cover 3A. The drive unit 8 moves the imaging unit 3 relative to the base 7 in the X, Y, and Z directions. The face support unit 9 fixes the subject's face. The exhaust port 5 is provided in the cover 3A of the imaging unit 3. The exhaust port 5 causes the air flowing inside the imaging unit 3 (inside the cover 3A) to flow out of the imaging unit 3 (outside the cover 3A) (details will be described later).

[0030] The operation unit 30 outputs an operation signal to the control unit 10 in response to an operation instruction input via the operation unit 30. For example, the operation unit 30 can use at least one of the following: a mouse, joystick, keyboard, touch panel, etc.

[0031] The display unit 125 is a display located on the shooting unit 3. The display unit 125 may also function as the operation unit 30. For example, the display unit 125 may also function as the operation unit 30 by having a touch panel function.

[0032] The imaging unit 3 (cover 3A) houses various optical systems (for example, imaging optical system 200 and OCT optical system 201) and the control unit 100. The imaging optical system 200 is protected by an enclosure 200A that covers the imaging optical system 200. The OCT optical system 201 is protected by an enclosure 201A that covers the OCT optical system 201. Of course, it is also possible to house and protect the imaging optical system 200 and the OCT optical system 201 in a single enclosure. The imaging unit 3 may also house a driver for controlling the optical scanner 108 (described later) provided in the OCT optical system 201.

[0033] Figure 3 is a schematic diagram of various optical systems. These include an imaging optical system 200, an OCT optical system 201, an indicator projection optical system 70, an anterior segment observation optical system 40, a fixation target projection optical system 80, and the like. In this embodiment, at least the imaging optical system 200 and the OCT optical system 201 share the objective optical system 220. Furthermore, the optical paths of the imaging optical system 200 and the OCT optical system 201 are coupled coaxially by a beam splitter 221, which is one of the optical path coupling members.

[0034] <Filming optics> Figure 4 is a diagram of the imaging optical system 200. In Figure 4, the objective optical system 220 is represented by a single objective lens 22 for convenience. Also in Figure 4, the pupil-conjugate position of the eye E under examination is marked with a '△' on the optical axis, and the fundus-conjugate position is marked with an '×' on the optical axis.

[0035] The imaging optical system 200 includes an illumination optical system 10a and a light-receiving optical system 10b. The illumination optical system 10a includes a light source unit 11, a lens 13, a slit-shaped member 15a, lenses 17a and 17b, a mirror 18, a perforated mirror 20, an objective lens 22, etc. The light-receiving optical system 10b includes an objective lens 22, a perforated mirror 20, lenses 25a and 25b, a slit-shaped member 15b, an image sensor 28, etc.

[0036] The light source unit 11 has multiple types of light sources with different wavelength bands. For example, the light source unit 11 has visible light sources 11a and 11b and infrared light sources 11c and 11d. Thus, the light source unit 11 of this embodiment is provided with two light sources for each wavelength. The two light sources of the same wavelength are arranged on the pupil conjugate plane, away from the optical axis L. The two light sources are arranged side by side along the X direction, which is the scanning direction in Figure 4, and are arranged axially symmetric with respect to the optical axis L. The outer shape of the two light sources may be a rectangle in which the direction intersecting the scanning direction is longer than the scanning direction.

[0037] Light from the two light sources passes through the lens 13 and irradiates the slit-shaped member 15a. In this embodiment, the slit-shaped member 15a has a translucent portion (opening) formed to be elongated along the Y direction. As a result, the illumination light is formed in a slit shape on the fundus conjugate surface (the region illuminated in a slit shape on the fundus Er is shown as indicated by the symbol B).

[0038] The slit-shaped member 15a is displaced by a drive unit (not shown) such that the light-transmitting portion crosses the optical axis L in the X direction. This enables scanning of the illumination light in this embodiment. In this embodiment, scanning is also performed by the slit-shaped member 15b on the light-receiving system side. In this embodiment, the slit-shaped members on the light-emitting side and the light-receiving side are driven in conjunction by a single drive unit (actuator). This forms a scanning unit including the slit-shaped members 15a and 15b. The scanning unit may be, for example, an optical chopper. For details of an optical system employing an optical chopper, please refer to, for example, "Japanese Patent Application Publication No. 2019-118721" by the present applicant.

[0039] In the illumination optical system 10a, the images from each light source are relayed by the optical system from lens 13 to objective lens 22 and formed on the pupil conjugate plane. In other words, pupil images from the two light sources are formed on the pupil conjugate plane at positions separated with respect to the scanning direction. In this way, in this embodiment, two illumination regions P1 and P2 on the pupil conjugate plane are formed as images of the two light sources.

[0040] Furthermore, the slit-shaped light passing through the slit-shaped member 15a is relayed by the optical system from lens 17a to objective lens 22 and formed as an image on the fundus Er. This creates a slit-shaped illumination light on the fundus Er. The illumination light is reflected on the fundus Er and extracted from the pupil Ep.

[0041] The perforated mirror 20 is an optical path coupling unit that connects the optical paths of the illumination optical system 10a and the light-receiving optical system 10b. The perforated mirror 20 reflects the illumination light from the light source unit 11 toward the eye E under examination, and allows a portion of the fundus reflected light from the eye E under examination, after passing through the aperture, to pass toward the image sensor 28. Various beam splitters other than the perforated mirror 20 can be used.

[0042] Since the aperture of the perforated mirror 20 is conjugate to the pupil of the eye being examined, the fundus reflected light used for imaging is limited to a portion that passes through the image of the perforated mirror aperture (pupil image) on the pupil of the eye being examined. For this reason, the image of the aperture on the pupil of the eye being examined becomes the light-receiving region J in this embodiment. The light-receiving region J is formed sandwiched between two illumination regions P1 and P2 (images of two light sources). Furthermore, as a result of appropriately setting the imaging magnification of each image, the diameter of the aperture, and the spacing between the two light sources, the light-receiving region J and the two illumination regions P1 and P2 are formed so that they do not overlap on the pupil.

[0043] The retinal reflected light that has passed through the aperture of the objective lens 22 and the perforated mirror 20 forms an image of the slit-shaped region of the retinal erythrocyte at the retinal conjugate position via lenses 25a and 25b. At this time, harmful light is removed because the light-transmitting portion of the slit-shaped member 15b is positioned at the imaging position.

[0044] The image sensor 28 is positioned in a conjugate location in the fundus. In this embodiment, a relay optical system 27 is provided between the slit-shaped member 15b and the image sensor 28, thereby creating a conjugate relationship between the slit-shaped member 15b and the image sensor 28 in the fundus. As a result, both the removal of harmful light and image formation are performed well. Alternatively, the relay optical system 27 between the image sensor 28 and the slit-shaped member 15b may be omitted, and the two may be placed in close proximity. In this embodiment, a device with a two-dimensional light-receiving surface is used as the image sensor 28. For example, a CMOS, a two-dimensional CCD, etc., may be used. The image of the slit-shaped region of the fundus Er, which is imaged in the light-transmitting portion of the slit-shaped member 15b, is projected onto the image sensor 28. The image sensor 28 is sensitive to both infrared and visible light.

[0045] In this embodiment, as the slit-shaped illumination light scans the fundus Er, an image of the scanning position on the fundus Er (a slit-shaped image) is sequentially projected for each scan line of the image sensor 28. In this way, the entire image of the scanning range is projected onto the image sensor 28 in a time-division manner. As a result, a frontal image of the fundus (a two-dimensional reflected image) is captured as the entire image of the scanning range.

[0046] In this embodiment, the scanning unit in the light-receiving optical system 10b was a device that mechanically scans the slit, but it is not necessarily limited to this. For example, the scanning unit on the light-receiving optical system 10b side may be a device that electronically scans the slit. As an example, if the image sensor 28 is a CMOS, the slit scanning may be realized by the rolling shutter function of the CMOS. In this case, by displacing the area exposed on the imaging surface in synchronization with the scanning unit in the illumination optical system 10a, harmful light can be removed while efficiently taking images. Furthermore, a liquid crystal shutter or the like can be used as a scanning unit that electronically scans the slit.

[0047] The imaging optical system 200 has a diopter correction unit. In this embodiment, diopter correction units (diopter correction optical systems 17 and 25) are provided in each of the independent optical paths of the illumination optical system 10a and the light receiving optical system 10b. However, the diopter correction unit may be provided in the common optical path of the illumination optical system 10a and the light receiving optical system 10b.

[0048] The imaging optical system 200 may further include an indicator projection optical system 50. The indicator projection optical system 50 projects two split indicators onto the fundus Er as focus indicators. The split indicators are used for focus detection.

[0049] <OCT optical system> The OCT optical system 201 (see FIG. 3) includes a measurement light source 102, a coupler (optical splitter) 104, a measurement optical system 106, a scanning unit (optical scanner) 108, a reference optical system 110, a light receiving element (detector) 120, and the like. For example, the measurement light source 102, the measurement optical system 106, the reference optical system 110, and the light receiving element 120 are connected to the coupler 104 by optical fibers.

[0050] The OCT optical system 201 splits the light emitted from the measurement light source 102 into measurement light (sample light) and reference light by the coupler 104. The OCT optical system 201 guides the measurement light to the tissue (here, the fundus Ef) of the eye to be examined E by the measurement optical system 106, and guides the reference light to the reference optical system 110. The OCT optical system 201 causes the light receiving element 120 to receive the interference light synthesized from the measurement light reflected by the tissue and the reference light.

[0051] The measurement light source 102 emits low-coherence light used as measurement light and reference light. The light emitted from the measurement light source 102 is split into measurement light and reference light by the coupler 104. The measurement light passes through an optical fiber and is then emitted into the air. The measurement light emitted into the air is condensed onto the tissue through the optical scanner 108 and the like of the measurement optical system 106. The measurement light reflected by the tissue returns to the optical fiber through the same optical path.

[0052] The optical scanner 108 scans the tissue with measurement light in a two-dimensional direction (XY direction). For example, the optical scanner 108 is positioned approximately conjugate to the pupil of the eye E being examined. As an example, the optical scanner 108 is equipped with two galvanometer mirrors. The reflection angles of the galvanometer mirrors are arbitrarily adjusted by the drive mechanism 107. As a result, the reflection direction of the measurement light changes, and the measurement light is irradiated to any position on the tissue. In other words, the irradiation position of the measurement light on the tissue is changed by the optical scanner 108. Needless to say, the configuration of the optical scanner 108 can be changed. For example, a polygon mirror, a resonant scanner, an acousto-optic element (AOM), etc., may be used as the optical scanner 108.

[0053] The reference optical system 110 generates reference light that is combined with the measurement light reflected by the tissue. The reference optical system 110 may be of the Michelson type or the Mach-Zehnder type. The reference optical system 110 reflects the light incident from the coupler 104 back to the coupler 104 by a reflective optical system (e.g., a reference mirror) and guides it to the photodetector 120. As another example, the reference optical system 130 may transmit the light incident from the coupler 104 without reflection and guide it to the photodetector 120.

[0054] The reference optical system 110 can change the optical path length difference between the measurement light and the reference light by moving optical elements in the optical path. In this embodiment, the optical path length difference is changed by moving the reference mirror in the optical axis direction. The configuration for changing the optical path length difference may be provided in the optical path of the measurement optical system 106.

[0055] The photodetector 120 detects an interference signal resulting from the combination of the measurement light and the reference light. For example, the photodetector 120 has a spectroscopic optical system (spectrometer) that spectrally separates the interference signal into its wavelength components (each frequency component). For example, the spectrometer consists of a diffraction grating and a line sensor. The interference signal detected by the photodetector 120 is output to the control unit 10.

[0056] For example, in Fourier-domain OCT, the spectral intensity of the interfering light (spectral interference signal) is detected by the photodetector 120, and a complex OCT signal is obtained by performing a Fourier transform on the spectral intensity data. Furthermore, by calculating the absolute value of the amplitude in the complex OCT signal, a depth profile (A scan signal) in a predetermined range is obtained. In addition, a B scan signal is obtained by arranging the depth profiles at each measurement point as the measurement light is scanned by the optical scanner 108. For example, OCT image data (tomographic image data) is obtained based on the B scan signal. Alternatively, three-dimensional OCT image data (three-dimensional tomographic image data) may be obtained by scanning the tissue in a two-dimensional direction with the measurement light and arranging the B scan signals at each scanning line. Furthermore, OCT frontal (enface) image data, when the tissue is viewed from a direction along the optical axis of the measurement light (frontal direction), may be obtained from the three-dimensional OCT image data.

[0057] Furthermore, motion contrast data is obtained from two or more OCT signals acquired from the same part of the tissue at different timings (different times). In other words, motion contrast data is obtained by performing analysis processing on multiple complex OCT signals. For example, two-dimensional motion contrast data is obtained by scanning the measurement light along a single scan line and arranging the motion contrast data at each scan position. Alternatively, three-dimensional motion contrast data may be obtained by scanning the measurement light in a two-dimensional direction (i.e., the XY direction along the optical axis of the measurement light). Furthermore, frontal (enface) motion contrast data, when the tissue is viewed from the front, may be obtained from the three-dimensional motion contrast data.

[0058] <Target projection optical system> The index projection optical system 70 projects an alignment index onto the cornea of ​​the eye E under examination. The index projection optical system 70 comprises a first index projection optical system 73 and a second index projection optical system 71. The first index projection optical system 73 projects parallel light (infinity light). The second index projection optical system 71 projects divergent light (finite distance light). The first index projection optical system 73 is arranged symmetrically in the 0-degree and 180-degree directions with respect to the optical axis L, and the second index projection optical system 71 is arranged concentrically in the directions of 45-degree, 90-degree, 135-degree, 225-degree, 270-degree, and 315-degree directions with respect to the optical axis L.

[0059] <Anterior segment observation optical system> The anterior segment observation optical system 40 images the anterior segment of the eye E under examination and acquires an anterior segment observation image. The anterior segment observation optical system 40 illuminates the anterior segment with infrared light and captures a frontal image of the anterior segment. The anterior segment observation optical system includes a light source 41, a half mirror 45, an imaging sensor 47, a dichroic mirror 43, an objective lens 22, etc. For example, the light source 41 is an infrared light source that illuminates the eye E under examination. For example, the imaging sensor 47 is a two-dimensional imaging sensor and is positioned optically conjugate to the pupil Ep. The dichroic mirror 43 and the objective lens 22 are shared with the imaging optical system 200.

[0060] <Fixation target projection optical system> The fixation target projection optical system 80 projects (presents) the fixation target to the eye E under examination. When the fixation target is seen by the subject, the movement of the gaze is suppressed. The fixation target projection optical system 80 may, for example, include a fixation target unit 81 and a relay lens 83, and may share the optical path of the imaging optical system 200 from the dichroic mirror 85 to the objective lens 22. The fixation target unit 81 emits visible light.

[0061] <Department Head> Figure 5 is a diagram of the configuration of the control unit 100. The control unit 100 has the necessary functions to perform control processing for each part, as well as various calculation and analysis processing. The control unit 100 is protected by an enclosure 100A that covers the control unit 100. The control unit 100 has at least a single-board computer (SBC) 301, which includes a CPU, RAM, ROM, storage unit, etc. The CPU is responsible for controlling the fundus imaging device 1. The CPU may consist of one or more processors. Various information is temporarily stored in the RAM. Various programs, initial values, etc. are stored in the ROM. The storage unit is a non-transient storage medium that can retain its contents even when the power supply is cut off. For example, a hard disk drive, flash ROM, USB memory, etc. may be used as the storage unit.

[0062] Furthermore, the control unit 100 includes a heat sink 300, a fan 6, etc. The heat sink 300 is positioned on top of the SBC 301. The heat sink 300 also absorbs the heat generated by the SBC 301 and dissipates it into the air. The fan 6 creates an airflow by blowing air. The fan 6 is arranged in parallel on the side of the control unit 100 (i.e., the side of the enclosure 100A). In this embodiment, two fans 6 are arranged in parallel in the longitudinal direction (Z direction in Figure 5) on the side of the control unit 100 (heat sink 300).

[0063] The control unit 100 is electrically connected to the drive unit 8, the operation unit 30, the display unit 125, the imaging optical system 200, the OCT optical system 201, the indicator projection optical system 70, the anterior segment observation optical system 40, the fixation target projection optical system 80, the memory unit, and the like.

[0064] <Arrangement of optical system and control unit, and airflow path> Figure 6 is a front view of the fundus imaging device 1. The arrangement of the optical system and control unit 100, and the airflow path will be explained with reference to Figure 6. Note that the display unit 120 is not shown in Figure 6.

[0065] Within the imaging unit 3 (cover 3A), the imaging optical system 200 (enclosure 200A) is positioned above the OCT optical system 201 (enclosure 201A). Furthermore, within the imaging unit 3, the control unit 100 (enclosure 100A) is positioned above the imaging optical system 200 (enclosure 200A). In other words, the control unit 100 is positioned above the mounting surface of enclosure 201A and the mounting surface of enclosure 200A. Additionally, the control unit 100 is positioned above the optical axis of the objective optical system 220 in the OCT optical system 201 and the imaging optical system 200. Moreover, the control unit 100 is positioned at approximately the same height as the exhaust port 5.

[0066] The imaging unit 3 (cover 3A) is not sealed, and a gap (not shown) is provided at the bottom of the imaging unit 3. Outside air flows into the imaging unit 3 using this gap as a vent, and flows out of the imaging unit 3 via the fan 6, heat sink 300, and exhaust port 5. More specifically, outside air flows into the imaging unit 3, flows along the flow path FL1, and reaches the fan 6 of the control unit 100. In the control unit 100, the SBC 301 generates heat in conjunction with the control of the fundus imaging device 1, and this heat is conducted to the heat sink 300. The heat sink 300 then dissipates this heat from its surface to the surroundings. Therefore, heated air remains in the upper part of the imaging unit 3 and around the control unit 100. The outside air flows along the flow path FL1 and is then blown by the fan 6, and together with the air heated by the SBC301, it passes along the flow path FL2 over the top of the imaging optical system 200 (enclosure 200A). Furthermore, the outside air is exhausted from the exhaust port 5 to the outside of the imaging unit 3 by the exhaust action of the fan 6.

[0067] In this embodiment, since the control unit 100 is positioned above the OCT optical system 201 and the imaging optical system 200, it is less susceptible to thermal changes such as optical axis misalignment caused by the rise of air heated by the control unit 100, and a certain level of accuracy can be maintained. Furthermore, since the control unit 100 is positioned at approximately the same height as the exhaust port 5, the air heated by the control unit does not circulate within the imaging unit 3. Therefore, heat does not spread to each optical system, and the control unit 100 can be cooled efficiently.

[0068] <Operation Description> The control operation of the fundus imaging device 1 will be explained.

[0069] The examiner registers or retrieves the subject's identification information (ID, name, age, etc.) and sets the shooting mode to be applied to the acquisition of an anterior fundus image or OCT image of the eye under examination. The examiner also operates the control unit 30 and presses the start switch to begin shooting the eye under examination. The control unit 100 controls various optical systems based on the operation instructions from the control unit 30.

[0070] For example, the control unit 100 controls the fixation target projection optical system 80 to turn on the fixation lamp of the fixation target unit 81. This guides the line of sight (in other words, the fixation position) of the eye being examined onto the optical axis L. The control unit 100 also controls the indicator projection optical system 70 to project an alignment indicator onto the cornea. Furthermore, the control unit 100 controls the anterior segment observation optical system 40 to sequentially acquire anterior segment observation images. For example, such anterior segment observation images may be displayed on the display unit 125.

[0071] In this embodiment, the position of the imaging unit 3 relative to the eye E is automatically moved based on the anterior segment observation image of the eye E under examination. The control unit 100 detects alignment index images contained in the anterior segment observation image by image processing of the anterior segment observation image. The control unit 100 also controls the drive unit 8 to adjust the alignment state of the imaging unit 3 relative to the eye E under examination based on the alignment index images.

[0072] The examiner presses the Capture button when the eye E is fixed on the fixation light and automatic alignment is complete. Based on the input of the operation signal from the Capture button, the control unit 100 controls the imaging optical system 200 to perform focus adjustment and captures a frontal image of the fundus. The control unit 100 also controls the OCT optical system 201 to perform optimization processing based on the input of the operation signal from the Capture button, causing the measurement light to scan the fundus Er and acquire the OCT signal (interference signal).

[0073] Next, the control unit 100 analyzes the OCT signal and obtains OCT data based on the OCT signal. Furthermore, the control unit 100 obtains an OCT image, which is an image of the OCT data, based on the OCT data. The control unit 100 also obtains segmentation results, which are obtained by segmenting the layers and boundaries of the tissue based on the OCT data. The control unit 100 may also generate an analysis map using the segmentation results (for example, a thickness map that shows the distribution of layer thickness in the fundus in two dimensions). The display unit 125 displays these OCT images, segmentation results, and analysis maps.

[0074] Furthermore, the more images of the fundus Er taken by the fundus imaging device 1 are taken, and the longer it is used, the higher the load on the control unit 100 becomes, and the more likely the control unit 100 is to overheat. However, within the imaging unit 3, the air heated by the control unit 100, along with the air entering from outside the imaging unit 3, is properly discharged from the exhaust port 5 through the aforementioned flow path without hitting any of the optical systems.

[0075] As explained above, in this embodiment, the fundus imaging device has the control unit located within the imaging unit rather than on the base, thus saving space on the base and reducing the installation area of ​​the device. Conventionally, combined devices that capture frontal fundus images in color and OCT images required an external control device (typically a PC) to perform at least one of the following: imaging control, display processing, and analysis processing. In contrast, in this embodiment, the control unit that performs at least the imaging control of the imaging optical system and the OCT optical system, the display control processing of the color image and the OCT image based on the OCT data, and the analysis processing of the OCT data is located within the imaging unit, so a compact device that performs imaging, display, and analysis standalone without an external PC can be realized.

[0076] However, in this case, the processing performed by the control unit (imaging control of the imaging optical system and the OCT optical system, display control processing of the color image and the OCT image based on the OCT data, and analysis processing of the OCT data) is high, so the control unit generates heat at high temperatures (for example, around 50-85°C). In contrast, within the imaging unit, the control unit is located above the imaging optical system and the OCT optical system, so the air heated by the control unit does not easily reach the imaging optical system and the OCT optical system. Therefore, even if the control unit is located within the imaging unit together with the imaging optical system and the OCT optical system, thermal changes in the imaging optical system and the OCT optical system are easily suppressed. A typical example of thermal change is the expansion of the components that hold each part of the optical system. As a result of this expansion, optical axis misalignment, changes in the overall optical path length, etc.

[0077] In this embodiment of the fundus imaging apparatus, the control unit is positioned above the optical axis of the objective optical system, so that the hot air generated by the control unit rises, reducing the possibility that at least the objective optical system may be affected by thermal changes.

[0078] In this embodiment of the fundus imaging apparatus, the control unit is positioned above the enclosure covering the imaging optical system and the OCT optical system. Therefore, the control unit is positioned above all the components that make up the optical system. Consequently, each optical system is less susceptible to the effects of thermal changes.

[0079] In the fundus imaging apparatus of this embodiment, the detector of the OCT optical system is located within the imaging unit. If the detector is housed in a base, the wiring between the control unit and the detector must take into account the movement of the imaging unit, which tends to complicate the configuration. In contrast, if the detector is located within the imaging unit together with the control unit, rather than in a base, the wiring and other configurations for electrically connecting the detector and the control unit can be simplified. Furthermore, the display unit may be attached to the imaging unit. This also simplifies the wiring and other configurations for electrically connecting the control unit and the display unit.

[0080] Furthermore, since the detector is located below the control unit, which is a heat source, even if the detector is placed together with the control unit in the imaging unit, heat from the control unit is less likely to reach the detector. This prevents, for example, a decrease in the signal-to-noise ratio (SNR) of the signal caused by a change in the overall optical path length of the spectrometer if the detector is a spectrometer. The spectrometer includes at least a plurality of optical elements, including a grading element that spectrally analyzes the interference light between the measurement light and the reference light, and a photodetector that detects the spectrally analyzed interference light, as well as a mount that holds the optical elements.

[0081] Furthermore, since the detector is located within the imaging unit rather than on the base, the base can be made more space-saving, thus reducing the overall installation area of ​​the device. This reduction in installation area is particularly significant when the detector is a spectrometer.

[0082] The fundus imaging apparatus of this embodiment is equipped with a blower mechanism for creating airflow and an exhaust port for releasing air. Air flows through the imaging unit by the blower mechanism and flows out of the imaging unit through the exhaust port, so that the heated air generated by the control unit can be efficiently discharged. Furthermore, when an air blower mechanism and an exhaust port are provided, by providing the air blower mechanism on the side of the control unit and the exhaust port at the same height as the control unit, air circulation within the imaging unit can be suppressed, and thermal changes in the imaging optical system and OCT optical system can be further suppressed.

[0083] In this embodiment of the fundus imaging apparatus, multiple air blowing mechanisms are arranged in parallel on the side of the control unit, allowing for more efficient exhaust of the heated air generated by the control unit. For example, if the air blowing mechanisms are arranged in parallel on the side of the control unit in the direction of the control unit's shorter side, some of the air blowing mechanisms will be positioned higher than the control unit, preventing all of the blown air from reaching the control unit. Consequently, the cooling efficiency will be poor. On the other hand, if the air blowing mechanisms are arranged in parallel on the side of the control unit in the direction of the control unit's longer side, the air blowing mechanisms will be positioned along the control unit, allowing all of the blown air from reaching the control unit. Consequently, the cooling efficiency will be higher.

[0084] <Example of transformation> The technology disclosed in this embodiment is merely an example. Therefore, it is possible to modify at least a part of the technology illustrated in this embodiment.

[0085] In this embodiment, the control unit 100 may be positioned at any location above the imaging optical system 200. That is, the control unit 100 may be positioned at any position on the XZ plane with respect to the top surface of the enclosure 200A, and at any position in the Y direction. However, considering the slimming of the width of the imaging unit 3, it is preferable to position the control unit 100 so that it does not protrude as much as possible from the top surface of the enclosure 200A.

[0086] Furthermore, in this embodiment, the control unit 100 can also be placed below the objective optical system 220. However, in this case, at least the objective optical system 220 becomes susceptible to thermal changes due to the rise of hot air generated by the control unit 100. [Explanation of Symbols]

[0087] 1. Fundus imaging device 8 Drive unit 10 Frontal imaging optical system 40 Anterior segment observation optical system 70 Index projection optical system 80 Fixation target projection optical system 100 Control Unit 120 Display section 200 imaging optical system 201 OCT optical system

Claims

1. Base and, Display unit and An imaging optical system for capturing at least a color image as a frontal image of the fundus of the eye under examination, An OCT optical system for acquiring OCT data of the fundus of the eye being examined, A control unit that performs at least the following: imaging control of the imaging optical system and the OCT optical system, display control processing of the OCT image based on the color image and the OCT data, and analysis processing of the OCT data; The imaging unit, which houses the imaging optical system, the OCT optical system, and the control unit, is positioned on the base. Equipped with, The fundus imaging apparatus is characterized in that, within the imaging unit, the control unit is positioned above the imaging optical system and the OCT optical system.

2. In the fundus imaging device according to claim 1, An optical path coupling member for coupling the optical path of the imaging optical system and the optical path of the OCT optical system, An objective optical system is positioned between the eye under examination and the optical path coupling member to guide light to the fundus, Equipped with, The fundus imaging apparatus is characterized in that the control unit is positioned above the optical axis of the objective optical system.

3. In the fundus imaging device according to claim 1 or 2, The fundus imaging apparatus is characterized in that the control unit is positioned above the enclosure covering the imaging optical system and the OCT optical system.

4. In a fundus imaging device according to any one of claims 1 to 3, The system further includes a drive unit for moving the imaging unit relative to the base, The OCT optical system has a detector that detects the interference light between the reflected light of the measurement light and the reference light. A fundus imaging apparatus characterized in that the detector is arranged within the imaging unit.

5. In a fundus imaging device according to any one of claims 1 to 4, The aforementioned imaging unit has an exhaust port for releasing air, Within the imaging unit, the control unit has a blower mechanism on its side for forming the airflow, The fundus imaging apparatus is characterized in that the air flows through the imaging unit by the blowing mechanism and flows out of the imaging unit through the exhaust port.

6. In the fundus imaging apparatus of claim 5, The fundus imaging apparatus is characterized in that the blowing mechanism comprises a plurality of blowing mechanisms arranged in parallel on the side surface of the control unit.

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