Ophthalmic optical system and ophthalmic device

Abstract

To provide an optical system that enables wide-range observation, reduces the number of times required to photograph the entire fundus, and further suppresses cost increase.SOLUTION: An ophthalmic optical system for observing a subject's eye (12) comprises an objective lens (130) that forms a pupil conjugate with a pupil of the subject's eye, and is configured to satisfy a conditional expression, 0.15≤D / L≤0.25, where L is a distance from a pupil position (Ps) conjugate with the pupil of the subject's eye to the pupil of the subject's eye (Pp), and D is a sum of a center thicknesses of lenses included in the objective lens (130).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an ophthalmic optical system and an ophthalmic apparatus. [Background technology]

[0002] US Patent Application Publication No. 2016 / 0150953 discloses an apparatus for photographing an eye to be examined using a scanning laser ophthalmoscope and an optical coherence tomography. Summary of the Invention

[0003] The first aspect of the technology of the present disclosure is An ophthalmic optical system for observing an eye to be examined, an objective optical system that forms a pupil conjugate with the pupil of the subject's eye; When the distance from a pupil position conjugate with the pupil of the subject's eye to the pupil of the subject's eye is L and the sum of the center thicknesses of the lenses included in the objective optical system is D, 0.1≦ D / L ≦0.25 It is an ophthalmic optical system that satisfies the conditional expression shown below.

[0004] A second aspect of the technology of the present disclosure is a scanning unit that scans light from a light source; an objective optical system having a lens group that forms a pupil conjugate with the pupil of the eye to be examined in the scanning unit; The objective optical system includes: When the distance from the scanning unit to the pupil of the subject's eye is L and the sum of the center thicknesses of the lens groups is D, 0.1≦ D / L ≦0.25 This is an ophthalmic apparatus that satisfies the conditional expression shown below.

[0005] It should be noted that the pupil of the subject's eye refers to the position where the device is positioned so that the pupil of the subject's eye coincides with the device when the device is used to examine and photograph the subject's eye, i.e., the "position corresponding to the pupil position of the subject's eye" with respect to the device, and it goes without saying that the subject's eye is not included as part of the device. In the following explanation, this position may be referred to as the "pupil position of the subject's eye" or simply as the "pupil of the subject's eye." [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic configuration diagram of an ophthalmologic apparatus according to a first embodiment. [Figure 2] 1 is a schematic diagram illustrating the configuration of a photographing optical system according to a first embodiment. [Figure 3] FIG. 2 is a schematic diagram showing an example of the specific configuration of a first lens group and a second lens group included in an objective lens that constitutes a photographing optical system. [Figure 4] FIG. 2 is a schematic diagram illustrating an example of a lens configuration of an objective lens according to Example 1. [Figure 5] 4 is an aberration diagram showing pupil aberration of the objective lens according to Example 1. FIG. [Figure 6] FIG. 10 is a schematic diagram illustrating an example of a lens configuration of an objective lens according to Example 2. [Figure 7] 10 is an aberration diagram showing pupil aberration of the objective lens according to Example 2. FIG. [Figure 8] FIG. 10 is a schematic diagram showing an example of a lens configuration of an objective lens according to Example 3. [Figure 9] 10A and 10B are aberration diagrams showing pupil aberration of the objective lens according to Example 3. [Figure 10] FIG. 10 is a schematic diagram illustrating an example of a lens configuration of an objective lens according to Example 4. [Figure 11] 10 is an aberration diagram showing pupil aberration of the objective lens according to Example 4. FIG. [Figure 12] FIG. 10 is a schematic diagram showing a configuration in which an attachment optical system according to a second embodiment can be attached to and detached from a mobile terminal. [Figure 13] FIG. 10 is a schematic diagram showing an example of the configuration of an attachment optical system according to a second example. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0008] [First embodiment]

[0009] An ophthalmic apparatus 110 according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an ophthalmic apparatus 110.

[0010] For ease of explanation, Scanning Laser Ophthalmoscope will be referred to as "SLO" and Optical Coherence Tomography will be referred to as "OCT."

[0011] When the ophthalmic apparatus 110 is placed on a horizontal plane, the horizontal direction is referred to as the "X direction," the vertical direction relative to the horizontal plane is referred to as the "Y direction," and the direction of the optical axis of the imaging optical system 116A is referred to as the "Z direction." The apparatus is positioned with respect to the subject's eye 12 so that the pupil center 27 of the subject's eye is positioned on the optical axis in the Z direction. The X direction, Y direction, and Z direction are perpendicular to each other.

[0012] The ophthalmologic apparatus 110 includes an imaging device 14 and a control device 16. The imaging device 14 includes an SLO unit 18 that acquires an image of the fundus 12A of the subject's eye 12, and an OCT unit 20 that acquires a tomographic image of the subject's eye 12. Hereinafter, a fundus image generated based on SLO data acquired by the SLO unit 18 will be referred to as an SLO image. Also, a tomographic image generated based on OCT data acquired by the OCT unit 20 will be referred to as an OCT image. Note that an SLO image may also be referred to as a two-dimensional fundus image. Also, an OCT image may also be referred to as a fundus tomographic image or an anterior segment tomographic image, depending on the region of the subject's eye 12 that is imaged. The ophthalmic apparatus 110 is an example of the "ophthalmic apparatus" of the technology of the present disclosure.

[0013] The control device 16 comprises a computer having a central processing unit (CPU) 16A, random access memory (RAM) 16B, read-only memory (ROM) 16C, and input / output (I / O) ports 16D.

[0014] The control device 16 includes an input / display device 16E connected to the CPU 16A via an I / O port 16D. The input / display device 16E has a graphic user interface that displays an image of the subject's eye 12 and receives various instructions from the user. A touch panel display may be used as the input / display device 16E. The control device 16 also includes a communication I / F 16F connected to the I / O port 16D.

[0015] The control device 16 also includes an image processing device 17 connected to the I / O port 16 D. The image processing device 17 generates an image of the subject's eye 12 based on the data obtained by the photographing device 14.

[0016] 1, the control device 16 of the ophthalmic apparatus 110 includes the input / display device 16E, but the technology of the present disclosure is not limited to this. For example, the control device 16 of the ophthalmic apparatus 110 may not include the input / display device 16E, but may include an input / display device that is physically independent from the ophthalmic apparatus 110. In this case, the display device includes an image processing processor unit that operates under the control of the CPU 16A of the control device 16. The image processing processor unit may display an SLO image or the like based on an image signal instructed to be output by the CPU 16A.

[0017] The photographing device 14 operates under the control of the control device 16. The photographing device 14 includes an SLO unit 18, a photographing optical system 116A, and an OCT unit 20. The photographing optical system 116A is moved in the X, Y, and Z directions by a photographing optical system driving unit (not shown) under the control of the CPU 16A. Alignment (positioning) between the photographing device 14 and the subject's eye 12 may be performed, for example, by moving not only the photographing device 14 but also the entire ophthalmic apparatus 110 in the X, Y, and Z directions.

[0018] The SLO system is realized by the control device 16, the SLO unit 18, and the imaging optical system 116A shown in FIG.

[0019] The SLO unit 18 includes multiple light sources. For example, as shown in FIG. 1 , the SLO unit 18 includes a light source 40 for B light (blue light), a light source 42 for G light (green light), a light source 44 for R light (red light), and a light source 46 for IR light (infrared light, e.g., near-infrared light). The light emitted from each of the light sources 40, 42, 44, and 46 is directed to the same optical path via optical elements 48, 50, 52, 54, and 56. The optical elements 48 and 56 are mirrors, and the optical elements 50, 52, and 54 are beam splitters. The B light is guided to the optical path of the imaging optical system 116A via the optical elements 48, 50, and 54. The G light is guided to the optical path of the imaging optical system 116A via the optical elements 50 and 54. The R light is guided to the optical path of the imaging optical system 116A via the optical elements 52 and 54. The IR light is guided to the optical path of the imaging optical system 116A via optical members 56 and 52. The light sources 40, 42, 44, and 46 can be LED light sources or laser light sources. An example using a laser light source will be described below. The optical members 48 and 56 can be total reflection mirrors. The optical members 50, 52, and 54 can be dichroic mirrors, half mirrors, etc. The light sources 40, 42, 44, and 46 are examples of the "light source" of the technology of the present disclosure.

[0020] The SLO unit 18 is configured to be switchable between various light emission modes, such as a light emission mode in which G light, R light, B light, and IR light are individually emitted, and a light emission mode in which all or some of these light sources are simultaneously emitted. In the example shown in FIG. 1 , four light sources are provided: a B light (blue light) light source 40, a G light source 42, an R light source 44, and an IR light source 46; however, the technology of the present disclosure is not limited to this. For example, the SLO unit 18 may further include a white light source. In this case, in addition to the various light emission modes described above, a light emission mode in which only white light is emitted may be set.

[0021] The laser light incident on the photographing optical system 116A from the SLO unit 18 is scanned in the X and Y directions by scanning units (120, 142) described later in FIG. 2. The scanning light passes through the pupil 27 and is irradiated onto the posterior segment (e.g., fundus 12A) of the subject's eye 12. The light reflected by the fundus 12A is incident on the SLO unit 18 via the photographing optical system 116A. The scanning units (120, 142) are an example of the "scanning unit" of the technology of the present disclosure.

[0022] The light reflected by the fundus 12A is detected by light detection elements 70, 72, 74, and 76 provided in the SLO unit 18. In this embodiment, the SLO unit 18 includes a B light detection element 70, a G light detection element 72, an R light detection element 74, and an IR light detection element 76 corresponding to the multiple light sources, namely, the B light source 40, the G light source 42, the R light source 44, and the IR light source 46. The B light detection element 70 detects B light reflected by the beam splitter 64. The G light detection element 72 detects G light that has passed through the beam splitter 64 and reflected by the beam splitter 58. The R light detection element 74 detects R light that has passed through the beam splitters 64 and 58 and reflected by the beam splitter 60. The IR light detection element 76 detects R light that has passed through the beam splitters 64 and 58 and reflected by the beam splitter 60. , 60 and detects the G light reflected by the beam splitter 62. The light detecting elements 70, 72, 74, 76 may be, for example, an APD (avalanche photodiode).

[0023] Under the control of the CPU 16A, the image processing device 17 generates SLO images corresponding to each color using signals detected by the B light detection element 70, the G light detection element 72, the R light detection element 74, and the IR light detection element 76. The SLO images corresponding to each color include a B-SLO image generated using the signal detected by the B light detection element 70, a G-SLO image generated using the signal detected by the G light detection element 72, an R-SLO image generated using the signal detected by the R light detection element 74, and an IR-SLO image generated using the signal detected by the IR light detection element 76. In a light emission mode in which the B light source 40, the G light source 42, and the R light source 44 emit light simultaneously, an RGB-SLO image may be synthesized from the B-SLO image, the G-SLO image, and the R-SLO image generated using the signals detected by the R light detection element 74, the G light detection element 72, and the B light detection element 70, respectively. Furthermore, in a light emission mode in which the G light source 42 and the R light source 44 emit light simultaneously, an RG-SLO image may be synthesized from a G-SLO image and an R-SLO image generated using the signals detected by the R light detection element 74 and the G light detection element 72. In the first embodiment, an RG-SLO image is used as the SLO image, but this is not limiting, and other SLO images may be used. The beam splitters 58, 60, 62, and 64 may be dichroic mirrors, half mirrors, or the like.

[0024] The OCT system is a three-dimensional image acquisition device realized by the control device 16, OCT unit 20, and imaging optical system 116A shown in Fig. 1. The OCT unit 20 includes a light source 20A, a sensor (detection element) 20B, a first optical coupler 20C, a reference optical system 20D, a collimating lens 20E, and a second optical coupler 20F.

[0025] The light source 20A generates light for optical coherence tomography. For example, a super luminescent diode (SLD) can be used as the light source 20A. The light source 20A generates low-coherence broadband light with a wide spectral bandwidth. The light emitted from the light source 20A is split by the first optical coupler 20C. One of the split beams is collimated by a collimating lens 20E as measurement light and then enters the imaging optical system 116A. The measurement light is scanned in the X and Y directions by scanning units (148, 142), which will be described later. The scanned light is irradiated onto the anterior segment of the subject's eye or the posterior segment via the pupil 27. The measurement light reflected from the anterior or posterior segment enters the OCT unit 20 via the imaging optical system 116A, and then enters the second optical coupler 20F via the collimating lens 20E and the first optical coupler 20C. In this embodiment, SD-OCT using an SLD as the light source 20A is exemplified, but the present invention is not limited to this, and SS-OCT using a wavelength swept light source instead of an SLD may also be adopted.

[0026] The other light beam emitted from the light source 20A and branched by the first optical coupler 20C is incident as reference light on the reference optical system 20D, passes through the reference optical system 20D, and then enters the second optical coupler 20F.

[0027] The measurement light (return light) reflected and scattered by the subject's eye 12 and the reference light are combined by the second optical coupler 20F to generate interference light. The interference light is detected by the sensor 20B. The image processing device 17 generates a tomographic image of the subject's eye 12 based on the detection signal (OCT data) from the sensor 20B.

[0028] In the first embodiment, the OCT system generates a tomographic image of the anterior or posterior segment of the subject's eye 12.

[0029] The anterior segment of the subject's eye 12 includes, as an anterior segment, the cornea, iris, angle, lens, ciliary body, and part of the vitreous body. The posterior segment of the subject's eye 12 includes, as a posterior segment, the remaining part of the vitreous body, the retina, choroid, and sclera. The vitreous body belonging to the anterior segment is the part of the vitreous body on the cornea side, with the XY plane passing through the point of the lens closest to the center of the eye as its boundary, and the vitreous body belonging to the posterior segment is the part of the vitreous body other than the vitreous body belonging to the anterior segment.

[0030] When the anterior segment of the subject's eye 12 is the imaging target region, the OCT system generates, for example, a tomographic image of the cornea. When the posterior segment of the subject's eye 12 is the imaging target region, the OCT system generates, for example, a tomographic image of the retina.

[0031] 2 shows a schematic configuration of the imaging optical system 116A. The imaging optical system 116A includes, arranged in this order from the subject's eye 12 side, an objective lens 130, a horizontal scanning unit 142, a relay lens device 140, a beam splitter 147, vertical scanning units 120 and 148, a focus adjustment device 150, and a collimator lens 20E. As the beam splitters 178 and 147, for example, a dichroic mirror, a half mirror, or the like can be used.

[0032] The horizontal scanning unit 142 is an optical scanner that horizontally scans the SLO laser light and OCT measurement light incident via the relay lens device 140. In this embodiment, the horizontal scanning unit 142 is shared by the SLO optical system and the OCT optical system, but this is not limited thereto. A horizontal scanning unit may be provided for each of the SLO optical system and the OCT optical system.

[0033] The collimator lens 20E converts the measurement light emitted from the end 158 of the fiber through which the light emitted from the OCT unit 20 travels into parallel light.

[0034] The focus adjustment device 150 includes a plurality of lenses 152, 154. The focus position of the measurement light on the subject's eye 12 is adjusted by appropriately moving each of the plurality of lenses 152, 154 in the optical axis direction according to the imaging region of the subject's eye 12. Although not shown, if a focus detection device is provided, the focus adjustment device can drive the lenses 152, 154 according to the focus detection state to automatically adjust the focus, thereby realizing an autofocus device.

[0035] The vertical scanning unit 148 is an optical scanner that scans the measurement light incident via the focus adjustment device 150 in the vertical direction.

[0036] The vertical scanning unit 120 is an optical scanner that scans the laser light incident from the SLO unit 18 in the vertical direction.

[0037] Relay lens device 140 includes multiple lenses 144, 146 each having positive power. Relay lens device 140 is configured by multiple lenses 144, 146 so that the positions of vertical scanning units 148, 120 and horizontal scanning unit 142 are conjugate with each other. More specifically, relay lens device 140 is configured so that the central positions of the angular scans of both scanning units are conjugate with each other.

[0038] The beam splitter 147 is disposed between the relay lens device 140 and the vertical scanning unit 148. The beam splitter 147 is an optical element that combines the SLO optical system and the OCT optical system, and reflects the SLO light emitted from the SLO unit 18 toward the relay lens device 140, and also reflects the measurement light emitted from the OCT unit 20 toward the relay lens device 140. The OCT measurement light and the SLO laser light are transmitted toward the test eye 12 via the objective lens 130, which constitutes a common optical system. The SLO laser light reflected by the test eye 12 is incident on the SLO unit 18 via the objective lens 130, the horizontal scanning unit 142, the relay lens device 140, the beam splitter 147, and the vertical scanning unit 142. The measurement light emitted from the OCT unit 20 is two-dimensionally scanned by the vertical scanning unit 148 and the horizontal scanning unit 142. The light emitted from the SLO unit 18 is two-dimensionally scanned by the vertical scanning unit 120 and the horizontal scanning unit 142, which constitute the SLO optical system. The two-dimensionally scanned OCT measurement light and the SLO laser light are incident on the test eye 12 via the objective lens 130, the horizontal scanning unit 142, the relay lens device 140, the beam splitter 147, and the vertical scanning unit 120. In addition, the OCT measurement light that has passed through the test eye 12 is incident on the OCT unit 20 via the objective lens 130, horizontal scanning unit 142, relay lens device 140, beam splitter 147, vertical scanning unit 148, focus adjustment device 150, and collimator lens 20E.

[0039] For example, a resonant scanner, a galvanometer mirror, a polygon mirror, a rotating mirror, a dowel prism, a double dowel prism, a rotation prism, a MEMS mirror scanner, an acousto-optical element (AOM), or the like is suitably used as the horizontal scanning unit 142 and the vertical scanning units 120 and 148. In this embodiment, a galvanometer mirror is used as the vertical scanning unit 148, and a polygon mirror is used as the vertical scanning unit 120. Note that if a two-dimensional optical scanner such as a MEMS mirror scanner is used instead of an optical scanner such as a polygon mirror or a galvanometer mirror, the incident light can be angle-scanned two-dimensionally by the reflecting element, and therefore the relay lens device 140 may be eliminated.

[0040] The objective lens 130 includes, in order from the horizontal scanning unit 142 side, a first lens group 134 and a second lens group 132, and at least the second lens group 132 is a positive lens group having positive power as a whole. In the first embodiment, the first lens group 134 is also a positive lens group having positive power as a whole. Each of the first lens group 134 and the second lens group 132 includes at least one positive lens. When each of the first lens group 134 and the second lens group 132 includes multiple lenses, each of the first lens group 134 and the second lens group 132 may include a negative lens as long as it has positive power as a whole.

[0041] The first lens group 134 is an example of the "first lens group" of the technology of the present disclosure, and the second lens group 132 is an example of the "second lens group" of the technology of the present disclosure.

[0042] The first lens group 134 and the second lens group 132 that constitute the objective lens 130 are separated by the longest air gap on the optical axis AX between the lens surfaces of the objective lens 130. Even if a glass plate without power is located between the first lens group 134 and the second lens group 132, the glass plate is not considered to be a lens belonging to either the first lens group 134 or the second lens group 132, and the first lens group 134 and the second lens group 132 are considered to be separated by the longest air gap. This longest air gap is convenient for providing a combining unit having light combining and light separating functions, such as a dichroic mirror.

[0043] The first lens group 134 and the second lens group 132 may be configured such that lenses arranged closer to the pupil conjugate position Ps than a fundus conjugate position that is conjugate with the fundus of the subject's eye 12 are classified into the first lens group 134, and lenses arranged closer to the subject's eye 12 than the fundus conjugate position are classified into the second lens group. The first lens group 134 and the second lens group 132 may be configured such that a boundary is formed between adjacent lenses at a predetermined interval, and lenses arranged closer to the pupil conjugate position Ps than the boundary are classified into the first lens group, and lenses arranged closer to the subject's eye 12 than the boundary are classified into the second lens group.

[0044] Although not shown, the photographing optical system 116A includes an optical module including a fixation lamp for presenting a fixation target, a camera, and an illumination device. The optical path of the illumination device can be arranged to be combined with the optical path of the imaging optical system 116A by a beam splitter or the like.

[0045] The photographing optical system 116A includes an objective lens 130 that functions as a posterior-segment observation optical system that observes at least the posterior segment of the subject's eye 12. The photographing optical system 116A includes an optical module for anterior-segment observation that is insertable into and detachable from the optical path of the objective lens 130, and by disposing the optical module for anterior-segment observation in the optical path of the objective lens 130, it is possible to switch from the posterior-segment observation optical system to the anterior-segment observation optical system. In the first embodiment, the photographing optical system 116A will be described mainly with reference to the posterior-segment observation optical system, and a description of the photographing optical system 116A that functions as an anterior-segment observation optical system in which an optical module for anterior-segment observation is disposed in the optical path of the objective lens 130 will be omitted.

[0046] FIG. 3 shows an example of a specific configuration of the first lens group 134 (G1) and the second lens group 132 (G2) included in the objective lens 130 that constitutes the imaging optical system 116A, which functions as a posterior segment observation optical system for observing the posterior segment of the subject's eye 12.

[0047] As shown in FIG. 3 , the objective lens 130 is disposed so that the scanning center position (position indicated as Ps in FIG. 3 ) of the horizontal scanning unit 142 and the vertical scanning unit 148 is conjugate with the pupil position Pp of the subject's eye 12. That is, the scanning center position of the scanning unit is a pupil position Ps conjugate to the pupil position Pp of the subject's eye 12 (hereinafter referred to as the pupil conjugate position). In the SLO optical system, the SLO laser light scanned by the vertical scanning unit 120 and the horizontal scanning unit 142 passes through the objective lens 130 and is angularly scanned two-dimensionally around the pupil position Pp of the subject's eye 12. As a result, the focal point of the SLO laser light is two-dimensionally scanned on the fundus 12A. Similarly, in the OCT optical system, the measurement light scanned by the vertical scanning unit 148 and the horizontal scanning unit 142 passes through the objective lens 130 and is angularly scanned two-dimensionally around the pupil position Pp of the subject's eye 12. As a result, the focal point of the measurement light is two-dimensionally scanned on the fundus 12 A. When observing the posterior segment of the eye, the SLO unit 18 acquires a two-dimensional fundus image, and the OCT unit 20 acquires a tomographic image of the fundus.

[0048] The objective lens 130 includes multiple lens groups, namely, a positive first lens group 134 (G1) and a positive second lens group 132 (G2). The positive first lens group 134 and the positive second lens group 132 form an afocal system. As shown in the figure, the first lens group 134 includes, in order from the pupil conjugate position Ps side, i.e., the nearest horizontal scanning unit 142 side (hereinafter referred to as the scanning unit side), toward the subject's eye side, a meniscus-shaped lens component (a cemented lens of lenses L11 and L12) with its convex surface facing the scanning unit side, and a positive lens L13 with its convex surface facing the scanning unit side. In this specification, the term "lens component" refers to a lens with two interfaces with air on the optical axis, and one lens component refers to one single lens or a set of cemented lenses formed by cementing multiple lenses together. The meniscus-shaped lens component of the first lens group 134 is effective for correcting chromatic aberration when it is configured as a cemented lens as shown in the figure, but can be configured as a single lens when the wavelength range of the light used is relatively narrow.

[0049] As an example, the second lens group 132 includes, in order from the scanning unit side to the eye to be examined, a biconvex positive lens component (a cemented lens of a positive lens L21 and a negative lens L22), a positive lens L23 with its convex surface facing the scanning unit side, and a positive meniscus lens L24 with its convex surface facing the scanning unit side. The biconvex positive lens component of the second lens group 132 is effective for correcting chromatic aberration when it is configured as a cemented lens as shown in the figure, but can be configured as a single lens when the wavelength range of light used is relatively narrow.

[0050] Here, the photographing optical system 116A forms a wide-angle optical system, thereby realizing observation of the fundus 12A in a wide field of view (FOV). indicates the range that can be photographed by the photographing device 14. The field of view FOV can be expressed as a field of view angle. In the first embodiment, the field of view angle can be defined by an internal illumination angle and an external illumination angle. The external illumination angle is the illumination angle of the light beam irradiated from the ophthalmic device 110 to the subject's eye 12, defined with the pupil 27 as the reference. The internal illumination angle is the illumination angle of the light beam irradiated to the fundus 12A, defined with the eyeball center O as the reference. The external illumination angle and the internal illumination angle correspond to each other. For example, if the external illumination angle is 120 degrees, the internal illumination angle corresponds to approximately 160 degrees.

[0051] Conventional fundus examination devices include those with a low field of view (FOV) of 30 to 45 degrees, for example, and those with a wide field of view (FOV) of over 100 degrees. A problem with low-field-of-view fundus examination devices is that the range that can be observed at one time is limited, and multiple images (e.g., seven images) may be required to expand the observation range. On the other hand, a problem with wide-field-of-view fundus examination devices is that the optical configuration is complex and large, resulting in high costs. Therefore, in the first embodiment, an optical system is provided that enables wide-area observation, reduces the number of images required to capture the entire fundus, and further reduces costs. Specifically, in the first embodiment, an objective lens is provided as an example of an ophthalmic optical system that can provide an ophthalmic examination device with a medium field of view (FOV) of approximately 70 degrees.

[0052] When forming an objective lens 130 with a medium-angle field of view, it is preferable to be able to form a field of view (FOV) that covers the observation range required by a doctor or the like for fundus observation. For example, the field of view (FOV) is the range that is covered when a predetermined number of observations (e.g., seven observations) are made within the observation range in a single observation according to the ETDRS (Early Treatment Diabetic Retinopathy Study). In this case, the field of view (FOV) of the objective lens 130 with a medium-angle field of view can be configured to satisfy the following conditional expression (1): 60 degrees≦FOV≦80 degrees (1)

[0053] With this configuration, by setting the FOV at 60 degrees or less, fundus observation with a medium field of view, which is the range that covers seven observations by ETDRS, becomes possible. Furthermore, by setting the FOV at 80 degrees or less, it becomes possible to suppress the increase in cost due to an increase in the lens diameter of the objective lens 130 and / or an increase in the number of lenses.

[0054] Conditional formula (1) may also stipulate that the field of view (FOV) exceeds 60 degrees. Conditional formula (1) may also stipulate that the field of view (FOV) is less than 80 degrees. The lower limit of the field of view (FOV) of 60 degrees is a preferable value for defining a range that covers seven observations using ETDRS. The upper limit of the field of view (FOV) of 80 degrees is a preferable value for suppressing cost increases due to an increase in the lens diameter of the objective lens 130 or an increase in the number of lenses. These upper and lower limit values ​​may vary depending on design conditions, and may be configured to satisfy at least one of the upper and lower limit values.

[0055] Incidentally, in order to obtain an ophthalmic apparatus with a medium angle of view (FOV of about 70 degrees), it is important to optimize pupil aberration. In the first embodiment, pupil aberration is defined as the transverse aberration on the image plane when ray tracing is performed with the scanning center of the scanning unit (pupil conjugate position Ps) as the object point and the pupil position (exit pupil position) as the image point. If this pupil aberration is larger than the pupil diameter of a human eye (for example, about 2 mm to 4 mm without mydriasis), the scanning light at the periphery of the field of view will be vignetted by the pupil when scanning with the scanning light. Pupil aberration increases as the field of view FOV increases. Therefore, correction (optimization) of pupil aberration is required to avoid vignetting of the scanning light at the pupil.

[0056] In the configuration example shown in FIG. 3, when forming an objective lens 130 with a medium field of view, the distance from a pupil conjugate position Ps conjugate with the pupil of the subject's eye 12 to a pupil position (pupil position) Pp of the subject's eye 12 is L, and the sum of the center thicknesses of the lenses included in the objective lens 130 is D, the following formula is obtained: The configuration is such that conditional expression (2) is satisfied. 0.1≦ D / L ≦0.25 (2)

[0057] This configuration enables SLO imaging with a medium angle of view, and also enables OCT imaging in the entire medium angle of view.

[0058] In conditional expression (2), the lower limit of 0.1 and the upper limit of 0.25 are preferable values ​​for reducing the total weight of the objective lens 130 and improving the transmittance of the objective lens 130. These upper and lower limit values ​​may vary depending on the design conditions, and at least one of the upper and lower limit values ​​may be satisfied. Note that, in order to reduce the total weight of the objective lens 130 and improve the transmittance of the objective lens 130, it is more preferable to satisfy the following conditional expression (3). 0.15≦ D / L ≦0.25 (3)

[0059] Furthermore, to obtain an ophthalmoscopy apparatus with a medium angle of view, it is necessary to optimize the angular magnification of the objective lens 130. Specifically, if the angular magnification is low, the angle of view becomes large, and the objective lens 130 becomes expensive. On the other hand, if the angular magnification is high, the required precision for scanning becomes high, and the cost becomes high. For this reason, it is necessary to optimize the angular magnification.

[0060] In the configuration example shown in Figure 3, when forming an objective lens 130 with a medium field of view, when the field angle from the pupil conjugate with the pupil of the subject's eye 12, i.e., the pupil conjugate position Ps, is θs and the field angle from the pupil of the subject's eye 12 is θp, the objective lens 130 is configured to satisfy the following conditional expression (4). 1.6≦ θp / θs ≦4.0 (4) With this configuration, by satisfying 1.6≦θp / θs, it is possible to prevent the lens diameter from increasing as the scanning angle of the scanning unit increases, and it is possible to suppress the increase in cost of the objective lens 130 in the imaging optical system with a medium field of view. Also, by satisfying θp / θs≦4.0, it is possible to suppress the difference between the field of view θs (scanning angle) and the field of view θp, and to suppress the influence of errors in the scanning element in the scanning unit. Furthermore, conditional expression (4) can be expressed as 1.6≦β≦4.0, where θp / θs is the angular magnification β.

[0061] In conditional expression (4), the lower limit of 1.6 is a preferable value for suppressing the increase in cost due to the increase in the diameter of the objective lens 130 as the angle of view from the pupil conjugate position Ps (the maximum scanning angle of the scanning unit) increases. The upper limit of 4.0 is a preferable value for suppressing the influence of errors in the scanning element (e.g., a galvanometer mirror) in the scanning unit. It is preferable to configure the objective lens 130 within the range of these upper and lower limit values. Also, the objective lens 130 may be configured to satisfy at least one of the upper and lower limit values. Note that, in consideration of the increase in the scanning angle of the scanning unit and the suppression of the influence of errors in the scanning element, it is also possible to configure the objective lens 130 to satisfy the following conditional expression (5). 0.15≦ θp / θs ≦4.0 (5)

[0062] In conditional expression (4), the angular magnification β is defined as θp / θs, but the same effect can be obtained with only the angle of view from the pupil conjugate position Ps (scanning angle of the scanning unit). That is, in the configuration example shown in Fig. 3, when an objective lens 130 with a medium field of view is formed, when the pupil conjugate with the pupil of the subject's eye 12, i.e., the angle of view from the pupil conjugate position Ps (maximum scanning angle of the scanning unit) is θs, it is possible to configure it so as to satisfy the following conditional expression (6). 30 degrees ≦ θs ≦ 45 degrees (6) With this configuration, by setting θs to 30 degrees or less, it is possible to suppress the influence of errors in the scanning element (for example, a galvanometer mirror). By setting θs to 45 degrees or less, it is possible to suppress the increase in cost due to the large diameter of the objective lens 130.

[0063] In conditional expression (6), the lower limit of 30 degrees is a preferable value for suppressing the influence of errors in the scanning element (e.g., a galvanometer mirror) in the scanning unit. The upper limit of 45 degrees is a preferable value for suppressing the increase in cost due to the increase in the diameter of the objective lens 130 as the angle of view from the pupil conjugate position Ps (the maximum scanning angle of the scanning unit) increases. These upper and lower limit values ​​may vary depending on the design conditions, and at least one of the upper and lower limit values ​​may be satisfied.

[0064] Incidentally, to obtain an ophthalmoscopy apparatus with a medium angle of view, the focal lengths of the first and second lens groups in the objective lens 130 have an effect. Specifically, the relationship between the focal lengths of the first and second lens groups can be affected by errors in the scanning element in the scanning unit, or can lead to increased costs due to an increase in the lens diameter. For this reason, it is necessary to optimize the relationship between the focal lengths of the first and second lens groups.

[0065] In the configuration example shown in FIG. 3, when the focal length of the first lens group of the objective lens 130 is f1 and the focal length of the second lens group is f2, the configuration is such that the following conditional expression (7) is satisfied. 0.3≦ f2 / f1 ≦0.6 (7) With this configuration, by making f2 / f1 0.3≦f2 / f1, it is possible to suppress the influence of errors in the scanning element in the scanning unit. Also, by making f2 / f1 ≦0.6, it is possible to suppress the increase in cost of the objective lens 130 in the photographing optical system with a medium angle of view.

[0066] In conditional expression (7), the lower limit of 0.3 is a preferable value for suppressing the influence of errors in the scanning element (e.g., a galvanometer mirror) in the scanning unit. The upper limit of 0.6 is a preferable value for suppressing the increase in cost due to the increase in the diameter of the objective lens 130 as the angle of view from the pupil conjugate position Ps (the maximum scanning angle of the scanning unit) increases. These upper and lower limit values ​​may vary depending on the design conditions, and at least one of the upper and lower limit values ​​may be satisfied.

[0067] To obtain an ophthalmoscopy apparatus with a medium angle of view (FOV of about 70 degrees), it is necessary to optimize the working distance of the objective lens 130. Specifically, if the working distance is short, there is a risk that the lens will interfere with the subject's eye 12 or the subject's face. On the other hand, if the working distance is long, the lens diameter must be increased, which increases costs. For this reason, optimization of the working distance is required.

[0068] In the configuration example shown in Figure 3, when the distance (working distance) from the end of the objective lens 130 on the test eye 12 side to the pupil position (pupil position) of the test eye 12 is WD, the objective lens 130 is configured to satisfy the following conditional expression (8). 20mm≦WD≦40mm (8) In this configuration, by configuring the objective lens 130 so that WD≦40 mm, it is possible to suppress increases in cost by suppressing increases in the diameter and number of lenses of the objective lens 130. By configuring the objective lens 130 so that WD is 20 mm≦WD, it is possible to avoid interference between the objective lens 130 and the subject's face. Note that WD may be the distance from the end of the objective lens 130 on the optical axis AX on the eye 12 side to the pupil position (pupil position) of the eye 12. Also, WD may be the distance from the end of the objective lens 130 on the optical axis AX on the eye 12 side to the end of the eye 12 side.

[0069] In conditional expression (8), the lower limit of 20 mm is a preferable value for suppressing an increase in the diameter of the objective lens 130 and an increase in the number of lenses. The upper limit of 40 mm is a preferable value for suppressing interference between the objective lens 130 and the subject's face. These upper and lower limit values ​​may vary depending on design conditions, and at least one of the upper and lower limit values ​​may be set to 0. It may be configured to satisfy this.

[0070] The above conditional expression (7) defines the ratio (f2 / f1) between the focal length f1 of the first lens group of the objective lens 130 and the focal length f2 of the second lens group, but it is also possible to obtain the same effect in the objective lens 130 by defining only the focal length f2 of the second lens group. That is, when the focal length of the second lens group is f2, the objective lens 130 can be configured to satisfy the following conditional expression (9). 40mm≦ f2 ≦60mm (9) With this configuration, by satisfying f2≦60 mm, it is possible to ensure the working distance WD of the objective lens 130, and by satisfying 40 mm≦f2, it is possible to suppress an increase in the diameter of the objective lens 130 or an increase in the number of lenses, thereby suppressing cost increases. The lower limit of 40 mm is a preferable value for ensuring a predetermined distance as the working distance WD of the objective lens 130. The upper limit of 60 mm is a preferable value for suppressing an increase in the diameter of the objective lens 130 or an increase in the number of lenses.

[0071] Incidentally, when an optical element, for example, a scanning element of a scanning unit (for example, a galvanometer mirror) is placed at the pupil conjugate position Ps, it is preferable to ensure a distance between the pupil conjugate position Ps and the scanning element so that the outer shape of the scanning element (including the range of movement if movement is required) does not interfere with the objective lens 130. For this reason, it is necessary to optimize the distance between the pupil conjugate position Ps and the element (for example, the scanning element) placed at the pupil conjugate position Ps.

[0072] In the configuration example shown in FIG. 3, when the distance from the end of the objective lens 130 on the scanning unit side to the pupil conjugate position Ps conjugate with the pupil of the subject's eye is d0, the objective lens 130 is configured to satisfy the following conditional expression (10): 15mm≦d0 (10) By configuring the objective lens 130 in this way, it is possible to suppress interference between the objective lens 130 and an element (for example, a scanning element) disposed at the pupil conjugate position Ps.

[0073] In conditional expression (10), the lower limit of 15 mm is a suitable condition for suppressing interference between the objective lens 130 and an element (for example, a scanning element) disposed at the pupil conjugate position Ps.

[0074] By configuring the objective lens 130 according to the first embodiment described above, it is possible to provide an ophthalmic device that reduces the number of times images can be taken to enable at least wide-area observation, suppresses cost increases, and enables observation at a medium angle of view (FOV) of approximately 70 degrees.

[0075] In the first embodiment, the case where light is scanned by the horizontal scanning unit 142 and the vertical scanning unit 148 has been described, but examples of the horizontal scanning unit 142 and the vertical scanning unit 148 include, but are not limited to, a polygon mirror or a galvanometer mirror. For example, other optical elements capable of scanning the scanning light in the Y direction may be used, and examples include a MEMS (Micro-electromechanical system) mirror, a rotating mirror, a prism, or a resonant mirror.

[0076] Furthermore, it goes without saying that the same scanning can be performed by switching the X direction and the Y direction in the scanning light in the first embodiment.

[0077] Preferred Embodiments Next, an example of the objective lens 130 of the technique of the present disclosure will be described.

[0078] Example 1 FIG. 4 shows an example of the lens configuration of the objective lens 130 according to the first embodiment. Reference numeral 60 denotes a dioptric system including lenses L11 to L24. 4 shows the pupil conjugate position Ps, which is common to the scanning center position of the scanning unit, and the pupil position (pupil position) Pp of the subject's eye 12. Note that Ps and Pp in the figure are shown to indicate positions in the optical axis direction, and do not indicate shapes or sizes. The objective lens 130 includes, in order from the scanning unit side, a first lens group 134 (G1) and a second lens group 132 (G2). In the following description, the first lens group 134 will be referred to as the first lens group G1, and the second lens group 132 will be referred to as the second lens group G2. The first lens group G1 and the second lens group G2 are separated by the longest air gap within the objective lens 130.

[0079] The first lens group G1 includes, in order from the pupil conjugate position Ps side (scanning unit side) to the eye to be examined, a negative meniscus lens L11 with a convex surface facing the scanning unit side, a positive lens L12 with a convex surface facing the scanning unit side, and a positive lens L13 with a convex surface facing the scanning unit side. The lenses L11 and L12 are cemented together to form a lens component in the shape of a positive lens with a convex surface facing the scanning unit side.

[0080] The second lens group G2 includes, in order from the scanning unit side to the examined eye side, a positive lens L21 having a convex surface facing the scanning unit side, a negative meniscus lens L22 having a concave surface facing the scanning unit side, a positive lens L23, and a positive meniscus lens L24 having a convex surface facing the scanning unit side. The lenses L21 and L22 are cemented together to form a lens component having a positive lens shape.

[0081] Table 1 shows the lens data for Example 1. The lens data shows, from the left column to the right, the surface number (No.), radius of curvature (R), surface spacing on the optical axis (D), refractive index (nd) based on the d-line (wavelength 587.56 nm), and Abbe number (vd) based on the d-line. The first surface in the lens data is the pupil conjugate position Ps, which is shared with the scanning center position of the scanning unit, and the value in the last row of the D column indicates the distance on the optical axis from the lens surface closest to the subject's eye in the table to the pupil position (pupil position) Pp. [Table 1]

[0082] Figure 5 shows the pupil aberration (lateral aberration at the exit pupil) of the objective lens configured with the specifications in Table 1. In the pupil aberration diagram shown in Figure 5, the vertical axis indicates the image height, the solid line indicates the central wavelength of 850.0 nm, the dashed line indicates 635.0 nm, the one-dot chain line indicates 532.0 nm, and the two-dot chain line indicates 488. It shows .0nm. As is clear from the pupil aberration diagram shown in Fig. 5, the objective lens of Example 1 clearly has excellent performance as an objective lens suitable for use in an ophthalmic apparatus with a medium angle of view FOV of about 70 degrees. Although not shown in the figure, it has been confirmed that various aberrations such as spherical aberration, astigmatism, and distortion are also well corrected.

[0083] Example 2 6 shows an example of the lens configuration of the objective lens 130 according to Example 2. Since Example 2 has the same configuration as Example 1, the same parts are given the same reference numerals and detailed description thereof will be omitted.

[0084] The first lens group G1 includes, in order from the pupil conjugate position Ps side (scanning unit side) to the eye to be examined, a negative meniscus lens L11 with a convex surface facing the scanning unit side, a positive lens L12 with a convex surface facing the scanning unit side, and a positive meniscus lens L13 with a concave surface facing the scanning unit side. The lenses L11 and L12 are cemented together to form a lens component with a positive lens shape.

[0085] The second lens group G2 includes, in order from the scanning unit side to the examined eye side, a positive lens L21 having a convex surface facing the scanning unit side, a positive lens L22 having a convex surface facing the scanning unit side, a negative meniscus lens L23 having a concave surface facing the scanning unit side, and a positive meniscus lens L24 having a convex surface facing the scanning unit side. The lenses L22 and L23 are cemented together to form a lens component having a positive lens shape.

[0086] Table 2 shows the lens data of Example 1. [Table 2]

[0087] Figure 7 shows the pupil aberration (lateral aberration at the exit pupil) of an objective lens configured with the specifications in Table 2. As is clear from the pupil aberration diagram shown in Fig. 7, the objective lens of Example 2 has excellent performance as an objective lens suitable for use in an ophthalmic apparatus with a medium field of view FOV of about 70 degrees. Although not shown in the figure, various aberrations such as spherical aberration, astigmatism, and distortion aberration are also included. It has been confirmed that the correction is also satisfactory.

[0088] Example 3 8 shows an example of the lens configuration of the objective lens 130 according to Example 3. Since Example 3 has the same configuration as Example 1, the same parts are given the same reference numerals and detailed description thereof will be omitted.

[0089] The first lens group G1 includes, in order from the pupil conjugate position Ps side (scanning unit side) to the eye to be examined, a negative meniscus lens L11 with a convex surface facing the scanning unit side, a positive lens L12 with a convex surface facing the scanning unit side, and a positive meniscus lens L13 with a concave surface facing the scanning unit side. The lenses L11 and L12 are cemented together to form a lens component with a positive lens shape.

[0090] The second lens group G2 includes, in order from the scanning unit side to the eye to be examined, a positive lens L21 with a convex surface facing the scanning unit side, a negative meniscus lens L22 with a concave surface facing the scanning unit side, and a positive lens L23. The lenses L21 and L22 are cemented together to form a lens component with a positive lens shape. The lens surface of the lens L23 closest to the eye to be examined 12 is aspheric.

[0091] Table 3 shows the lens data of Example 3. [Table 3]

[0092] The aspherical surfaces listed in Table 3 are expressed by the equation below, where h is the height in the direction perpendicular to the optical axis, zs is the distance along the optical axis from the tangent plane at the vertex of the aspherical surface to the position on the aspherical surface at height h, c is the inverse of the paraxial radius of curvature, k is the conic coefficient, A is the fourth-order aspherical coefficient, B is the sixth-order aspherical coefficient, C is the eighth-order aspherical coefficient, D is the tenth-order aspherical coefficient, and E is the twelfth-order aspherical coefficient. zs=(c·h 2 ) / 〔1+{1-(1+k)·h 2 ·c 2} 1 / 2 〕 +A·h 4 +B·h 6 +C·h 8 +D·h 10 +E·h 12

[0093] Table 4 shows the aspherical coefficients of the aspherical surface of Example 3. In Table 4, the aspherical coefficient A is expressed as C4, B as C6, and C as C8. Also, the aspherical coefficients D and E are omitted. "En" (n is an integer) in Table 4 is expressed as "×10 -n " means. [Table 4]

[0094] Figure 9 shows the pupil aberration (lateral aberration at the exit pupil) of an objective lens configured with the specifications in Tables 3 and 4. 9, it is clear that the objective lens of Example 3 has excellent performance as an objective lens suitable for use in an ophthalmic apparatus with a medium angle of view FOV of about 70 degrees. Although not shown in the figure, it has been confirmed that various aberrations such as spherical aberration, astigmatism, and distortion are also well corrected.

[0095] Example 4 10 shows an example of the lens configuration of the objective lens 130 according to Example 4. Since Example 4 has the same configuration as Example 1, the same parts are given the same reference numerals and detailed description thereof will be omitted.

[0096] The first lens group G1 includes, in order from the pupil conjugate position Ps side (scanning unit side) to the eye to be examined side, a negative meniscus lens L11 with its concave surface facing the scanning unit side, a positive lens L12 with its convex surface facing the scanning unit side, and a positive lens L13. The lenses L11 and L12 are cemented together to form a lens component with a positive lens shape.

[0097] The second lens group G2 includes, in order from the scanning unit side to the examined eye side, a positive lens L21 having a convex surface facing the scanning unit side, a negative meniscus lens L22 having a concave surface facing the scanning unit side, a positive meniscus lens L23 having a convex surface facing the scanning unit side, and a positive meniscus lens L24 having a convex surface facing the scanning unit side. The lenses L21 and L22 are cemented together to form a lens component having a positive lens shape.

[0098] Table 5 shows the lens data for Example 4. [Table 5]

[0099] Figure 11 shows the pupil aberration (lateral aberration at the exit pupil) of an objective lens configured with the specifications in Table 5. 11, it is clear that the objective lens of Example 2 has excellent performance as an objective lens suitable for use in an ophthalmic apparatus with a medium angle of view FOV of about 70 degrees. Although not shown in the figure, it has been confirmed that various aberrations such as spherical aberration, astigmatism, and distortion are also well corrected.

[0100] Next, the suitability of the above conditional expressions for the objective lenses in each of the above-mentioned Examples 1 to 4 will be described. Table 6 shows values ​​related to the above-mentioned conditional expressions for each of Examples 1 to 4. [Table 6]

[0101] As is clear from Table 6, the objective lenses of Examples 1 to 4 meet the above-mentioned conditional expressions.

[0102] Second Embodiment Next, a second embodiment will be described. In the second embodiment, the objective lens 130, which is a main part of the imaging optical system 116A according to the first embodiment, is formed as an attachment optical system that can be attached to and detached from a portable terminal having an imaging function. The configuration of the second embodiment is substantially the same as that of the first embodiment, so the same parts are given the same reference numerals and their description will be omitted, and the differences will mainly be described.

[0103] FIG. 12 shows an example of a configuration in which the attachment optical system 300 according to the second embodiment can be attached to and detached from a mobile terminal 400 having a photographing function.

[0104] As shown in Fig. 12, mobile terminal 400 includes photographing unit 402 for realizing a photographing function. Photographing unit 402 is configured to operate in a normal photographing mode for photographing an object at infinity, such as a landscape, in response to a user's operation of an operation unit (not shown) provided on mobile terminal 400. That is, photographing unit 402 of mobile terminal 400 includes mobile terminal lens 404 (Fig. 13), and is configured to form an image on image sensor 406 (Fig. 13) when parallel light is incident thereon in the normal photographing mode.

[0105] Fig. 13 shows an example of the configuration of the attachment optical system 300 according to the second example. Fig. 13 shows the attachment optical system 300 attached to the mobile terminal 400. The attachment optical system 300 includes a first lens group G1 and a second lens group G2 that constitute the objective lens 130 described above. The configurations of the first lens group G1 and the second lens group G2 are the same as those in the first embodiment, and therefore detailed description thereof will be omitted.

[0106] The attachment optical system 300 according to the second embodiment differs from the objective lens 130 according to the first embodiment in that it includes an illumination unit 304 that irradiates illumination light and a half mirror 302 that guides the illumination light from the illumination unit to an optical path along the optical axis AX. The illumination unit 304 irradiates illumination light that illuminates the subject's eye 12. The half mirror 302 guides the illumination light from the illumination unit 304 to an optical path along the optical axis AX.

[0107] If mobile terminal 400 is equipped with a subject illumination unit that illuminates a subject, attachment optical system 300 may be equipped with an optical system that collects illumination light emitted from the subject illumination unit and guides the illumination light from the subject illumination unit to an optical path along optical axis AX, instead of illumination unit 304 and half mirror 302. Furthermore, illumination unit 304 may be configured independently of attachment optical system 300.

[0108] The attachment optical system 300 includes an attachment section 306 for attaching the attachment optical system 300 to the portable terminal 400 so that the attachment optical system 300 and the portable terminal 400 can be detachably connected to each other. By including this attachment section 306 in the attachment optical system 300, the attachment optical system 300 can be detachably connected to the portable terminal 400.

[0109] The first lens group G1 and the second lens group G2 included in the attachment optical system 300 function as an objective optical system 301 that forms a pupil conjugate with the pupil of the subject's eye 12. The attachment optical system 300 and the portable terminal 400 are fixed by the mounting unit 306 so that the entrance pupil of the photographing unit 402 of the portable terminal 400 is positioned at the position of the pupil conjugate with the pupil of the subject's eye 12 formed by the objective optical system 301 (pupil conjugate position Ps). With this configuration, it is possible to take a fundus image of the subject's eye 12 with a simple configuration in which the attachment optical system 300 is simply attached to the portable terminal 400.

[0110] Although the technology of the present disclosure has been described using embodiments, the technical scope of the present disclosure is not limited to the scope described in the above embodiments. Various modifications or improvements can be made to the above embodiments without departing from the spirit of the invention, and such modifications or improvements are also included in the technical scope of the present disclosure. Furthermore, all documents, patent applications, and technical standards described in this specification are incorporated by reference in this specification to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated to be incorporated by reference. [Explanation of symbols]

[0111] 110 Ophthalmological equipment 17 Image processing device 20C First optical coupler 40, 42, 44, 46 light source 70, 72, 74, 76 Photodetector elements 132 First lens group 134 Second lens group 142 horizontal scanning unit 148 Vertical scanning unit

Claims

[Claim 1] An ophthalmic optical system for observing an eye to be examined, an objective optical system that forms a pupil conjugate with the pupil of the subject's eye; When the distance from a pupil position conjugate with the pupil of the subject's eye to the pupil of the subject's eye is L and the sum of the center thicknesses of the lenses included in the objective optical system is D, 0.15≦D / L≦0.25 An ophthalmic optical system that satisfies the conditional expression shown below.

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