Ophthalmologic apparatus

Abstract

To provide an ophthalmologic apparatus that allows a subject to visually recognize a fixation target clearly at low cost regardless of the state of an eye to be examined.SOLUTION: An ophthalmologic apparatus 1 for measuring eye refractive power of an eye E to be examined includes: a target projection optical system 15 for projecting a light flux of a fixation target onto the eye to be examined, which at least includes a light flux emission part (a target display part 15a) for emitting the light flux of the fixation target and a lens (focusing lens 15e) through which the light flux of the fixation target passes; and a focal depth expansion part (pin hole 100a) provided in the target projection optical system 15 for expanding the focal depth of the target projection optical system. The positions of the light flux emission part and the lens in the target projection optical system are fixed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an ophthalmic apparatus that projects a light beam of a fixation target onto an eye to be examined. [Background technology]

[0002] There is a well-known ophthalmic device that performs so-called refraction measurement to measure the ocular refractive power (spherical power, cylindrical power, and astigmatism axis angle, etc.) as ocular characteristics of the subject's eye (see, for example, Patent Document 1). Refraction measurement includes rough measurement and main measurement. In the rough measurement, the ocular refractive power of the subject's eye is measured while the subject fixates on a fixation target. In the main measurement, the fixation target or focusing lens (movable lens) is moved from a reference position (a position visible to the subject) determined based on the results of the rough measurement to a clouded position, and the ocular refractive power of the subject's eye is measured while the subject looks at the fixation target in a clouded state (a state in which accommodation tension is relaxed).

[0003] Conventionally, in reflex measurement, the power is adjusted by driving a moving mechanism including a motor to adjust the position of the fixation target or the focusing lens according to the power of the examinee. In addition, in the ophthalmic device described in Patent Document 1, the position of the focusing lens is adjusted so that the change of the fixation target from the reference position to the cloudy position can be visually recognized even by the examinee's eye with a small pupil. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-165819 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in an ophthalmic device performing reflex measurement such as the ophthalmic device described in Patent Document 1, the position of the fixation target or the focusing lens is adjusted by driving a moving mechanism according to the dioptric power of the examinee, but if the examinee's eye has astigmatism or high-order aberration, the examinee may not be able to clearly see the fixation target. In addition, an ophthalmic device performing reflex measurement needs to be provided with a moving mechanism for the fixation target, etc., which increases the manufacturing cost.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to provide an ophthalmic apparatus that is low-cost and allows a subject to clearly view a fixation target regardless of the condition of the subject's eye. [Means for solving the problem]

[0007] An ophthalmic apparatus for achieving the object of the present invention is an ophthalmic apparatus for measuring the ocular refractive power of a test eye, which comprises at least a light beam emitting unit that emits a light beam from a fixation target and a lens through which the light beam from the fixation target passes, a target projection optical system that projects the light beam from the fixation target onto the test eye, and a focal depth extension unit provided in the target projection optical system that extends the focal depth of the target projection optical system, and the positions of the light beam emitting unit and the lens in the target projection optical system are fixed.

[0008] This ophthalmologic apparatus has a simple configuration and allows the subject to clearly view the fixation target.

[0009] In the ophthalmologic apparatus according to another aspect of the present invention, the focal depth extending unit limits the numerical aperture of the visual target projecting optical system, thereby enabling the focal depth of the visual target projecting optical system to be extended.

[0010] In the ophthalmologic apparatus according to another aspect of the present invention, the focal depth extending unit has a pinhole arranged on the optical path of the light beam of the fixation target and at a position conjugate with the pupil of the subject's eye, thereby enabling the focal depth of the target projection optical system to be extended.

[0011] In an ophthalmic apparatus according to another aspect of the present invention, the light beam emitting unit has a laser light source as a light source of the light beam of the fixation target, the target projection optical system has a light scanning unit that scans the light beam of the fixation target projected onto the subject's eye, and the focal depth extending unit is a laser light source, thereby enabling the focal depth of the target projection optical system to be extended.

[0012] In an ophthalmic apparatus according to another aspect of the present invention, the focal depth extending section is a focal depth extending optical element or a multifocal optical element arranged at a position conjugate with the pupil of the subject's eye.

[0013] In an ophthalmologic apparatus according to another aspect of the present invention, the visual target projection optical system diverges a light beam of a fixation target to be projected onto the subject's eye, thereby making it possible to make the diopter of the fixation target more negative in accordance with the tendency of human diopter to be more negative. Effect of the Invention

[0014] The present invention enables a subject to clearly view a fixation target at low cost regardless of the condition of the subject's eye. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a side view of the ophthalmologic apparatus according to the first embodiment. [Diagram 2] FIG. 2 is a diagram showing a configuration of an optical system of a measuring head according to the first embodiment. [Diagram 3] 3 is an enlarged view of a pinhole plate of the visual target projection optical system in FIG. 2. [Figure 4] 1 is a graph showing an example of the relationship between the focal depth (D) and the numerical aperture (NA) of a visual target projection optical system. [Diagram 5] 13 is a diagram showing a configuration of an optical system of a measurement head of an ophthalmic apparatus according to a second embodiment. FIG. [Figure 6] 13 is an enlarged view of a part of a visual target projection optical system provided in a measurement head of an ophthalmic apparatus according to a third embodiment. FIG. [Figure 7] 1A and 1B are side and front views of a multifocal lens, which is an example of a special lens. [Figure 8]1A and 1B are a side view and a front view of an extended depth of focus lens, which is an example of a special lens. [Figure 9] 13 is an enlarged view of a part of a visual target projection optical system provided in a measurement head of an ophthalmic apparatus according to a fourth embodiment. FIG. [Figure 10] 13 is a diagram showing a configuration of an optical system of a measurement head of an ophthalmic apparatus according to a fifth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [First embodiment] 1 is a side view of an ophthalmic apparatus 1 according to a first embodiment. Among the mutually orthogonal XYZ directions (three directions) in the figure, the Y direction is the up-down direction, the Z direction is the front-back direction (also called the working distance direction) parallel to the front direction approaching the subject's eye E (subject) and the rear direction away from the subject, and the X direction is the left-right direction perpendicular to both the up-down direction and the front-back direction.

[0017] [Overall configuration of ophthalmic equipment] The ophthalmic apparatus 1 is an autorefractive keratometer that objectively measures eye characteristics such as eye refractive power and corneal shape of a subject's eye E. The ophthalmic apparatus 1 includes a base 2, a face support unit 3, a drive mechanism 4, a measurement head 5, and a display unit 6.

[0018] A face support unit 3 and a drive mechanism 4 are provided on the base 2.

[0019] The face support part 3 has a chin rest part 3a for supporting the chin of the subject and a forehead rest part 3b against which the forehead of the subject comes into contact, and supports the face of the subject. The position of the chin rest part 3a can be adjusted in the Y direction (up and down direction) by an actuator (not shown).

[0020] The drive mechanism 4 is composed of an actuator (not shown), such as a motor. The drive mechanism 4 moves the measurement head 5 in the X, Y and Z directions relative to the base 2. This allows the measurement head 5 to move in the X, Y and Z directions relative to the subject's eye E, making it possible to align the measurement head 5 with the subject's eye E in the X, Y and Z directions.

[0021] The measurement head 5 has a function of measuring the ocular refractive power and corneal shape of the subject's eye E. A display unit 6 is attached to this measurement head 5. In addition, various optical systems (including an image sensor, various light sources, and various driving units) corresponding to the measurement of the ocular refractive power and corneal shape, and a control device 9 are provided inside the measurement head 5.

[0022] The display unit 6 is, for example, a touch panel monitor. The display unit 6 is rotatably held by the measurement head 5, and the position and orientation can be manually adjusted. The display unit 6 displays an observation image of the subject's eye E acquired by the measurement head 5, the measurement results of the ocular refractive power and corneal shape of the subject's eye E, a setting menu screen for performing various settings, and an operation menu screen for performing various operations. The display surface of the display unit 6 accepts input operations by the examiner through touch operations, and therefore functions as an operation unit of the ophthalmic apparatus 1. Note that the ophthalmic apparatus 1 may be provided with a known operation unit other than the display unit 6.

[0023] The display surface of the display unit 6 functions as an operation unit that accepts input operations by the examiner through touch operations. Note that the ophthalmologic apparatus 1 may be provided with a known operation unit other than the display unit 6.

[0024] [Configuration of the optical system of the measurement head] Fig. 2 is a diagram showing the configuration of the optical system of the measurement head 5 of the first embodiment. As shown in Fig. 2, the optical system of the measurement head 5 includes an observation optical system 12, a Z alignment optical system 13, an XY alignment optical system 14, a visual target projection optical system 15, a measurement pattern projection optical system 16, and a light receiving optical system 17.

[0025] (Configuration of the observation optical system) The observation optical system 12 is an optical system used for observing the anterior part of the subject's eye E and photographing the anterior part. The observation optical system 12 has a main optical axis O1 parallel to the Z direction. In the observation optical system 12, an objective lens 12a, a dichroic filter 12b, a half mirror 12c, a relay lens 12d, a dichroic filter 12e, an imaging lens 12f, and a CMOS (complementary metal oxide semiconductor) type or CCD (charge coupled device) type image sensor 12g are arranged along the main optical axis O1 in this order from the subject's eye E side. The observation optical system 12 also has an illumination light source (not shown). Note that each part constituting the observation optical system 12 is a known technique, and therefore detailed description thereof will be omitted.

[0026] Illumination light emitted from an illumination light source of the observation optical system 12 illuminates the anterior segment of the subject's eye E and is reflected by the anterior segment. This reflected light is incident on the objective lens 12a, passes through each part of the observation optical system 12 from the objective lens 12a, and is incident on the imaging surface of the imaging element 12g. As a result, the reflected light is imaged by the imaging element 12g, and an observation image (image data) of the anterior segment of the subject's eye E is obtained by the imaging element 12g. The imaging element 12g outputs the observation image to the control device 9.

[0027] Around the objective lens 12a, a kerato plate 12h and a kerato ring light source 12i are provided for use in kerato measurement, which is an objective measurement of the corneal shape of the cornea Ec of the subject's eye E. The kerato plate 12h and the kerato ring light source 12i project a single or multiple ring-shaped light beam onto the cornea Ec. The ring-shaped light beam reflected by the cornea Ec is incident on the imaging surface of the imaging element 12g via the objective lens 12a and the dichroic filter 12b, etc. As a result, a kerato ring image is captured by the imaging element 12g. The imaging element 12g outputs the kerato ring image (image data) to the control device 9.

[0028] (Z alignment optical system) The Z alignment optical system 13 is used to detect the alignment state of the measurement head 5 in the Z direction with respect to the subject's eye E. The Z alignment optical system 13 is provided at two locations behind the keratoconus plate 12h (on the imaging element 12g side). Each Z alignment optical system 13 has an alignment light source 13a and a projection lens 13b. Each alignment light source 13a emits a light beam toward the projection lens 13b. A pair of light beams emitted from each alignment light source 13a is converted into parallel light beams by each projection lens 13b, and then passes through a pair of transmission holes (not shown) in the keratoconus plate 12h to be projected onto the cornea Ec.

[0029] A pair of light beams reflected by the cornea Ec are incident on the imaging surface of the imaging element 12g via the objective lens 12a and the dichroic filter 12b. As a result, a pair of bright spot images are captured by the imaging element 12g, and the imaging element 12g outputs the pair of bright spot images (image data) to the control device 9. As a result, the pair of bright spot images are displayed on the display unit 6 together with the observation image and the keratinizing image described above. Then, the control device 9 automatically or the examiner manually drives the driving mechanism 4 to move the measurement head 5 in the Z direction so that the keratinizing image and the pair of bright spot images have a predetermined positional relationship, thereby performing alignment in the Z direction (Z alignment). Note that Z alignment may be performed using other known methods.

[0030] (XY alignment optical system) The XY alignment optical system 14 is used to detect the alignment state of the measurement head 5 in the X and Y directions with respect to the subject's eye E. The XY alignment optical system 14 forms an optical path branched from the observation optical system 12 via a half mirror 12c. The XY alignment optical system 14 has an alignment light source 14a and a projection lens 14b. The alignment light source 14a emits a light beam toward the projection lens 14b. The light beam emitted from the alignment light source 14a is converted into a parallel light beam by the projection lens 14b, reflected by the half mirror 12c, and projected onto the cornea Ec via the dichroic filter 12b and the objective lens 12a.

[0031] The light beam reflected by the cornea Ec is incident on the imaging surface of the imaging element 12g via the objective lens 12a and the dichroic filter 12b. As a result, a bright spot image is captured by the imaging element 12g, and the imaging element 12g outputs the bright spot image (image data) to the control device 9. As a result, the display unit 6 can display a bright spot image for XY alignment together with the above-mentioned observation image, keratinizing image, and pair of bright spot images. Then, the control device 9 automatically or the examiner manually drives the driving mechanism 4 to adjust the position of the bright spot image in the X direction and the Y direction, thereby performing alignment in the X direction and the Y direction (XY alignment). Note that other known methods may be used for XY alignment.

[0032] (Configuration of visual target projection optical system) The target projection optical system 15 projects a light beam of a fixation target onto the fundus Ef of the subject's eye E when measuring the ocular refractive power of the subject's eye E.

[0033] The target projection optical system 15 includes a target display unit 15a, a focusing lens 15e, a relay lens 15f, a field lens 15g, a pinhole plate 100, a reflecting mirror 15i, dichroic filters 15j and 15b, and an objective lens 12a.

[0034] In addition, the target projection optical system 15 has an optical axis O2 parallel to the aforementioned main optical axis O1, and on this optical axis O2, the above-mentioned target display unit 15a, focusing lens 15e, relay lens 15f, field lens 15g, pinhole plate 100, and reflecting mirror 15i are arranged.

[0035] The target display unit 15a corresponds to the light beam emitting unit of the present invention, and various display devices (devices) such as a dot matrix liquid crystal display (LCD) and a matrix light emitting diode (LED) are used. The target display unit 15a displays a fixation target and emits a light beam of the fixation target toward a focusing lens 15e, which corresponds to a lens of the present invention. Since the target display unit 15a is a dot matrix LCD or the like, the display mode (shape, etc.) and display position of the fixation target can be set arbitrarily. The target display unit 15a can also display a target for measuring visual acuity in addition to a fixation target.

[0036] In addition, the position of the target display unit 15a is fixed on the optical axis O2 together with the focusing lens 15e. That is, the target projection optical system 15 is not provided with a moving mechanism for moving the target display unit 15a and the focusing lens 15e.

[0037] The light beam of the fixation target displayed on the target display unit 15a passes through a focusing lens 15e, then passes through a relay lens 15f, a field lens 15g, a pinhole plate 100, a reflecting mirror 15i, dichroic filters 15j and 12b, and an objective lens 12a, and is projected onto the subject's eye E. This makes it possible to present a fixation target or the like to the subject's eye E.

[0038] The pinhole plate 100 corresponds to the focal depth extending portion of the present invention, and is disposed at a position conjugate with the pupil of the subject's eye E on the optical axis O2, more specifically, at a position between the field lens 15g and the reflecting mirror 15i. The pinhole plate 100, which will be described in detail later, extends (deepens) the focal depth of the target projection optical system 15. The extension of the focal depth of the target projection optical system 15 here means extending the focal depth of the target projection optical system 15 more than when the pinhole plate 100 is not disposed.

[0039] (Configuration of the measurement pattern projection optical system) The measurement pattern projection optical system 16 projects a light beam of a ring-shaped measurement pattern used for refraction measurement, which is an objective measurement of the ocular refractive power of the subject's eye E, onto the fundus Ef.

[0040] The measurement pattern projection optical system 16 includes a reflector light source device 16a, a relay lens 16b, a conical prism 16c, a field lens 16d, a ring aperture 16e, a hole prism 16f, a rotary prism 16g, a dichroic filter 15j, a dichroic filter 12b, and an objective lens 12a.

[0041] The measurement pattern projection optical system 16 also has an optical axis O3 parallel to the above-mentioned main optical axis O1 and optical axis O2. On this optical axis O3, a reflector light source device 16a, a relay lens 16b, a conical prism 16c, a field lens 16d, a ring diaphragm 16e, and a holed prism 16f are arranged.

[0042] The reflector light source device 16a emits light along an optical axis O3 under the control of the control device 9. The reflector light source device 16a is disposed so as to be freely movable back and forth along the optical axis O3, and is moved back and forth on the optical axis O3 by an interlocking movement mechanism 27 described later.

[0043] The light emitted from the reflector light source device 16a passes through the relay lens 16b and then enters the conical surface of the conical prism 16c. The light that enters the conical surface of the conical prism 16c is deflected and exits from the bottom surface of the conical prism 16c. The conical prism 16c is disposed at a position close to the pupil conjugate position (approximate pupil conjugate position). The light that exits from the bottom surface of the conical prism 16c passes through the field lens 16d and then passes through a light transmitting portion formed in a ring shape on the ring aperture 16e.

[0044] The aperture ring 16e is disposed at a pupil conjugate position and has a light transmitting portion corresponding to the ring-shaped measurement pattern. The aperture ring 16e may be formed by deposition or the like on the lens surface of the field lens 16d or on the bottom surface of the conical prism 16c.

[0045] The light (ring-shaped light beam) that passes through the light-transmitting portion of the ring aperture 16e is reflected by the reflecting surface of the perforated prism 16f, passes through the rotary prism 16g, and is reflected by the dichroic filter 15j. The light reflected by the dichroic filter 15j is reflected by the dichroic filter 12b, passes through the objective lens 12a, and is projected onto the fundus Ef. As a result, a ring-shaped light beam for measurement is projected onto the fundus Ef. Note that the light beam for measurement is projected onto the fundus Ef with its shape distorted by the ocular refractive power of the subject's eye E.

[0046] The configuration of the measurement pattern projection optical system 16 from the relay lens 16b to the objective lens 12a is not particularly limited to the example shown in Figure 2, and can be modified as appropriate, as long as it is possible to project a light beam of a ring-shaped measurement pattern onto the fundus Ef.

[0047] (Configuration of the light receiving optical system) The light receiving optical system 17 receives fundus reflected light, which is reflected light of the measurement pattern projected onto the fundus Ef by the measurement pattern projection optical system 16. The light receiving optical system 17 includes an objective lens 12a, dichroic filters 12b and 15j, a rotary prism 16g, a holed prism 16f, a field lens 17a, a reflecting mirror 17b, a relay lens 17c, a focusing lens 17d (also referred to as a moving lens), a reflecting mirror 17e, a dichroic filter 12e, an imaging lens 12f, and an image sensor 12g.

[0048] The light receiving optical system 17 also has an optical axis O4 parallel to the above-mentioned main optical axis O1, optical axis O2, and optical axis O3. A reflecting mirror 17b, a relay lens 17c, a focusing lens 17d, and a reflecting mirror 17e are arranged on the optical axis O4.

[0049] The focusing lens 17d is disposed so as to be movable forward and backward along an optical axis O4 of the light receiving optical system 17. The focusing lens 17d is moved forward and backward on the optical axis O4 by an interlocking movement mechanism 27, which will be described later.

[0050] The fundus reflected light is incident on the light receiving surface of the image sensor 12g via the objective lens 12a, the dichroic filters 12b and 15j, the rotary prism 16g, the hole of the perforated prism 16f, the field lens 17a, the reflecting mirror 17b, the relay lens 17c, the focusing lens 17d (also called a moving lens), the reflecting mirror 17e, the dichroic filter 12e, and the imaging lens 12f. The image sensor 12g captures the fundus reflected light and outputs a reflecting image (image data) to the control device 9.

[0051] The interlocking movement mechanism 27 moves the reflex light source device 16a and the focusing lens 17d together in a direction (Z direction) parallel to the main optical axis O1 (optical axes O2 to O4). Although not shown, the interlocking movement mechanism 27 includes a holding member that holds the reflex light source device 16a and the focusing lens 17d together, a slide mechanism that holds the holding member so that it can slide in the Z direction, and an actuator such as a motor that moves the holding member back and forth in the Z direction.

[0052] The control device 9 comprehensively controls the operation of each part of the ophthalmic apparatus 1, and performs alignment of the measurement head 5 with respect to the subject's eye E and measurement of eye characteristics of the subject's eye E [corneal shape measurement (keratometry) and eye refractive power measurement (REF measurement)].

[0053] The control device 9 comprehensively controls the operation of each part of the ophthalmic apparatus 1, and performs alignment of the measurement head 5 with respect to the subject's eye E, corneal shape measurement (keratometry), and eye refractive power measurement (REF measurement).

[0054] Before starting keratometry or reflex measurement, the control device 9 controls the observation optical system 12, the keratoring light source 12i, the Z alignment optical system 13, the XY alignment optical system 14, the visual target projection optical system 15, etc., to perform alignment detection in a known manner to detect the relative position of the measurement head 5 in the XYZ directions with respect to the subject's eye E. Next, the control device 9 drives the drive mechanism 4 to move the measurement head 5 in the XYZ directions based on the detection result of the alignment detection, thereby performing auto-alignment of the measurement head 5 in the XYZ directions with respect to the subject's eye E.

[0055] When performing keratometry of the subject's eye E, the control device 9 controls the observation optical system 12, the keratometry ring light source 12i, the target projection optical system 15, etc., after completing the auto-alignment, to start the keratometry of the subject's eye E. Specifically, the control device 9 turns on the keratometry ring light source 12i to project a single or multiple ring-shaped light beams onto the cornea Ec, and causes the imaging element 12g to capture an image of the ring-shaped light beams reflected by the cornea Ec. Next, the control device 9 calculates the corneal shape (corneal refractive power, corneal astigmatism, corneal astigmatism axis angle, etc.) of the subject's eye E by a known method based on the keratometry ring image (not shown) output from the imaging element 12g.

[0056] When performing reflex measurement of the subject's eye E, the control device 9 controls the target projecting optical system 15, the measurement pattern projecting optical system 16, and the light receiving optical system 17 after completing the auto-alignment to start the reflex measurement of the subject's eye E. This reflex measurement includes a rough measurement and a main measurement.

[0057] Specifically, after completing the auto-alignment, the control device 9 controls the target projection optical system 15 (target display unit 15a) to present a fixation target to the eye E, thereby making the eye E fixate the fixation target. Next, the control device 9 controls the measurement pattern projection optical system 16 and the light receiving optical system 17 to start the rough measurement. As a result, a ring-shaped measurement pattern light beam is projected from the measurement pattern projection optical system 16 to the fundus Ef, and the image sensor 12g of the light receiving optical system 17 captures the fundus reflected light and outputs a refraction image. Then, the control device 9 calculates the provisional ocular refractive power of the eye E by a known method based on the refraction image output from the image sensor 12g in the rough measurement. Furthermore, the control device 9 drives the interlocking movement mechanism 27 based on the calculation result of the provisional ocular refractive power to move the focusing lens 17d to a focusing position (conjugate position) where the fundus Ef and the image sensor 12g are conjugate.

[0058] After the focusing lens 17d has been moved, the control device 9 controls the measurement pattern projection optical system 16 and the light receiving optical system 17 to start the main measurement. As a result, a ring-shaped measurement pattern light beam is projected from the measurement pattern projection optical system 16 onto the fundus Ef, and the image pickup element 12g of the light receiving optical system 17 picks up an image of the fundus reflected light and outputs a refraction image. Then, the control device 9 calculates the ocular refractive power of the subject's eye E by a known method based on the refraction image output from the image pickup element 12g in the main measurement.

[0059] 3 is an enlarged view of the pinhole plate 100 of the visual target projection optical system 15 in FIG. 2. As shown in FIG. 3, the pinhole plate 100 has a pinhole 100a arranged on the optical axis O2 (on the optical path of the light beam of the fixation target) and at a conjugate position with the pupil of the subject's eye E. The pinhole 100a adjusts the numerical aperture (NA) of the visual target projection optical system 15. For example, the numerical aperture (NA) of the visual target projection optical system 15 increases as the diameter of the pinhole 100a increases, and conversely, the numerical aperture (NA) of the visual target projection optical system 15 decreases as the diameter of the pinhole 100a decreases. In this embodiment, the focal depth of the visual target projection optical system 15 is expanded by adjusting the diameter of the pinhole 100a so as to limit the numerical aperture (NA) of the visual target projection optical system 15.

[0060] Fig. 4 is a graph showing an example of the relationship between the focal depth (D) and the numerical aperture (NA) of the target projecting optical system 15. As shown in Fig. 4, the focal depth (D) and the numerical aperture (NA) of the target projecting optical system 15 satisfy the relationship shown in the following [Equation 1], where the wavelength of the light beam of the fixation target is "λ", the refractive index of the medium (air) is "n", and a constant that varies depending on the optical characteristics of the device and the eye E to be examined is "k".

[0061]

number

[0062] 4 and the above-mentioned formula 1, the pinhole 100a limits the numerical aperture (NA) of the target projecting optical system 15, thereby expanding the focal depth of the target projecting optical system 15. As a result, even if the power of the subject's eye E (subject) is different from the power of the fixation target presented to the subject, the subject can clearly view the fixation target.

[0063] In this embodiment, the diopter range of the subject desired to be able to fixate on the fixation target is determined, and the focal depth of the target projection optical system 15, more specifically the numerical aperture (NA) [diameter of the pinhole 100a], is determined based on that diopter range.

[0064] [First example of numerical aperture (NA)] For example, a numerical aperture (NA) that makes the image of the fixation target seen by the subject uniform in a diopter range of ±3 [D] was calculated by simulation, and the numerical aperture (NA) of the target projection optical system 15 is approximately 0.05 or less. Here, the upper limit of the numerical aperture (NA) of the target projection optical system 15 may be greater than 0.05, but when the projection magnification of the fixation target with respect to the subject's eye E is changed, the numerical aperture (NA) of the target projection optical system 15 required to maintain the image of the fixation target seen by the subject also changes, so it is desirable for this numerical aperture (NA) to be 0.1 or less with some margin.

[0065] [Second example of numerical aperture (NA)] When the visual acuity value of the test eye E is equivalent to 0.1, in order to realize a focal depth of the target projection optical system 15 that allows the test subject to clearly view the fixation target within a range of ±2.5 [D], if the focal length of the test eye E is 17 mm, the light receiving side NA of the test eye E is expressed by the following equation [Equation 2].

[0066]

number

[0067] If the focal length of the projection side (optotype projection optical system 15) is 30 mm, the numerical aperture NA of the optotype projection optical system 15 is 0.0015×30 / 17 ≒ 0.0026. In this case, the condition for expanding the focal depth of the optotype projection optical system 15 is that the numerical aperture NA of the optotype projection optical system 15 is 0.0026 or less. However, in practice, it is necessary to set an appropriate numerical aperture NA, taking into account the influence of the diffraction limit.

[0068] As described above, in the ophthalmic device 1 of the first embodiment, the pinhole 100a is used to limit the numerical aperture (NA) of the target projection optical system 15, thereby expanding the focal depth of the target projection optical system 15. Therefore, the subject can clearly view the fixation target without moving the target display unit 15a or the focusing lens 15e according to the power of the subject's eye E as in the conventional method, and therefore a mechanism for moving the target display unit 15a and the like is not required. In addition, in order to expand the focal depth of the target projection optical system 15, it is only necessary to provide the pinhole plate 100 in the target projection optical system 15, so that the focal depth of the target projection optical system 15 can be expanded with a simple configuration. Furthermore, by expanding the focal depth of the target projection optical system 15, the subject can clearly view the fixation target even if the subject's eye E has astigmatism or high-order aberration. As a result, the subject can clearly view the fixation target regardless of the condition of the subject's eye E at low cost.

[0069] [Second embodiment] 5 is a diagram showing the configuration of the optical system of the measurement head 5 of the ophthalmic apparatus 1 of the second embodiment. In the ophthalmic apparatus 1 of the first embodiment, the pinhole 100a (pinhole plate 100) is used to limit the numerical aperture (NA) of the visual target projecting optical system 15 in order to expand the focal depth of the visual target projecting optical system 15, but the ophthalmic apparatus 1 of the second embodiment uses a different method to limit the numerical aperture (NA) of the visual target projecting optical system 15.

[0070] 5, the ophthalmic apparatus 1 of the second embodiment has basically the same configuration as the ophthalmic apparatus 1 of the first embodiment, except that a laser diode 102 and a light scanning unit 104 are provided in the optotype projection optical system 15 instead of the optotype display unit 15a and the pinhole plate 100 of the first embodiment. Therefore, the same reference numerals are used for the components that are the same in function or configuration as those of the first embodiment, and the description thereof will be omitted.

[0071] The laser diode 102 is a point light source corresponding to the laser light source and focal depth extension unit of the present invention, and emits laser light toward the focusing lens 15e. This laser light is projected onto the subject's eye E via the focusing lens 15e, the relay lens 15f, the field lens 15g, the optical scanning unit 104 described below, the dichroic filters 15j and 12b, and the objective lens 12a. By using the laser diode 102 as the light source of the target projection optical system 15, the numerical aperture (NA) of the target projection optical system 15 can be limited in the same way as in the case of using the pinhole 100a of the first embodiment.

[0072] The optical scanning unit 104 is an optical scanner (e.g., a galvano scanner) that rotates the reflecting mirror 15i to scan the laser light projected onto the subject's eye E along a predetermined fixation target pattern. In this case, the number of reflecting mirrors 15i may be multiple.

[0073] As described above, in the second embodiment of the ophthalmic device 1, the numerical aperture (NA) of the target projecting optical system 15 is limited by the laser diode 102, so that the focal depth of the target projecting optical system 15 can be expanded as in the first embodiment, thereby obtaining the same effect as the ophthalmic device 1 of the first embodiment described above.

[0074] [Third embodiment] 6 is an enlarged view of a part of the visual target projecting optical system 15 provided in the measurement head 5 of the ophthalmic apparatus 1 of the third embodiment. In the ophthalmic apparatus 1 of each of the above embodiments, the numerical aperture (NA) of the visual target projecting optical system 15 is limited by using a pinhole 100a or a laser diode 102 in order to extend the focal depth of the visual target projecting optical system 15. In contrast, the ophthalmic apparatus 1 of the third embodiment extends the focal depth of the visual target projecting optical system 15 by using a different method.

[0075] 6, the ophthalmic apparatus 1 of the third embodiment has basically the same configuration as the ophthalmic apparatus 1 of the first embodiment, except that a special lens 106 is provided in the visual target projecting optical system 15 instead of the pinhole plate 100 described in the first embodiment. Therefore, the same reference numerals are used for the same components in terms of function or configuration as those in the first embodiment, and the description thereof will be omitted.

[0076] The special lens 106 corresponds to the focal depth extending unit of the present invention. Like the pinhole 100a (pinhole plate 100) of the first embodiment, the special lens 106 is disposed at a conjugate position with the pupil (pupil) of the subject's eye E on the optical axis O2 (on the optical path of the light beam of the fixation target), and extends the focal depth of the target projection optical system 15.

[0077] Fig. 7 is a side view (see symbol VIIA) and a front view (see symbol VIIB) of a multifocal lens, which is an example of the special lens 106. Fig. 8 is a side view (see symbol VIIIA) and a front view (see symbol VIIIB) of a focal depth extension lens, which is an example of the special lens 106.

[0078] The special lens 106 is an extended depth of focus (EDOF) lens (extended depth of focus optical element) as shown in Fig. 7 or a multifocal lens (multifocal optical element) as shown in Fig. 8. Multifocal lenses and extended depth of focus lenses are composed of multiple regions with different diopters and have multiple foci. Therefore, multifocal lenses and extended depth of focus lenses can form an image of a fixation target at multiple diopter positions, allowing the subject to clearly view the fixation target regardless of the subject's diopter.

[0079] Incidentally, since the imaging performance of a multifocal lens decreases outside its focal point, a focal depth extension lens is more suitable as the special lens 106.

[0080] As described above, in the third embodiment of the ophthalmic device 1, the focal depth of the visual target projection optical system 15 is extended using a special lens 106 (a multifocal lens and a focal depth extension lens), thereby obtaining the same effect as the ophthalmic device 1 in each of the above embodiments.

[0081] [Fourth embodiment] 9 is an enlarged view of a part of the visual target projecting optical system 15 provided in the measurement head 5 of the ophthalmic apparatus 1 of the fourth embodiment. In the ophthalmic apparatus 1 of each of the above embodiments, the focal depth of the visual target projecting optical system 15 is expanded, but since the diopter of a human being tends to be negative (myopia), the diopter of the fixation target is made negative in the ophthalmic apparatus 1 of the fourth embodiment. Specifically, in the ophthalmic apparatus 1 of the fourth embodiment, the light beam of the fixation target projected from the visual target projecting optical system 15 to the subject's eye E is diverged.

[0082] 9, the ophthalmic apparatus 1 of the fourth embodiment has basically the same configuration as the ophthalmic apparatus 1 of each of the above-mentioned embodiments, except that the position of the optotype display unit 15a (laser diode 102) is different. Therefore, the same reference numerals are used to designate the same components as those of the above-mentioned embodiments in terms of function or configuration, and the description thereof will be omitted.

[0083] The target display unit 15a in the fourth embodiment (the same applies to the laser diode 102 in the second embodiment) is positioned closer to the focusing lens 15e (left side in the figure) than in the above embodiments so as to be disposed at a position conjugate with the fundus Ef of the subject's eye E in -2D to -3D. Note that instead of adjusting the position of the target display unit 15a, the position of the focusing lens 15e may be adjusted so that the target display unit 15a is conjugate with the fundus Ef of the subject's eye E in -2D to -3D.

[0084] As described above, in the ophthalmic device 1 of the fourth embodiment, the light beam of the fixation target projected from the target projection optical system 15 onto the test eye E is diverged, so that the diopter of the fixation target can be made more negative in accordance with the tendency of human diopter to be more negative.

[0085] [Fifth embodiment] Fig. 10 is a diagram showing the configuration of the optical system of the measurement head 5 of the ophthalmic apparatus 1 of the fifth embodiment. As shown in Fig. 10, the ophthalmic apparatus 1 of the fifth embodiment has basically the same configuration as the ophthalmic apparatus 1 of each of the above embodiments, so that the same components as those of the above embodiments in terms of function or configuration are denoted by the same reference numerals and the description thereof will be omitted.

[0086] In the ophthalmic apparatus 1 of each of the above-mentioned embodiments, the reflex light source device 16a and the focusing lens 17d are moved integrally by the interlocking movement mechanism 27, but the positions of the reflex light source device 16a and the focusing lens 17d may be fixed by omitting the interlocking movement mechanism 27 as in the ophthalmic apparatus 1 of the fifth embodiment. This allows the cost of the ophthalmic apparatus 1 to be further reduced.

[0087] In the ophthalmic apparatus 1 of each of the above embodiments, the focal depth of the target projection optical system 15 is expanded, but even in this case, there is a risk that all subjects cannot clearly view the fixation target. For this reason, in the ophthalmic apparatus 1 of the fifth embodiment, a lens switching device 110 is arranged instead of the focusing lens 15e of each of the above embodiments. This lens switching device 110 can selectively arrange multiple types of lenses 110a on the optical axis O2. This makes it possible to arrange the lens 110a corresponding to the state of the subject's eye E on the optical axis O2. In addition, it is possible to switch the lens 110a arranged on the optical axis O2 in multiple patterns (for example, 5D steps after rough measurement).

[0088] In the ophthalmic apparatus 1 of each of the above embodiments, the subject's eye E is not adjusted to a cloudy vision state during the main measurement, so there is a risk that the main measurement will be performed in a state in which the accommodation of the subject's eye E is not sufficiently relaxed. For this reason, the control device 9 of the fifth embodiment performs a time-series measurement (continuous measurement) as the main measurement, and checks the ocular refractive power (power) of the subject's eye E while monitoring the refraction image obtained by the time-series measurement. Thereby, when the subject's eye E is being adjusted, a change appears in the power of the subject's eye E, so that the accommodation state of the subject's eye E can be monitored. As a result, it is possible to determine whether the measurement result of the main measurement was measured in a state in which the accommodation of the subject's eye E was not sufficiently relaxed.

[0089] [others] In the above embodiments, an autorefractometer has been described as an example of the ophthalmic apparatus 1 of the present invention, but the present invention can be applied to various ophthalmic apparatuses (ocular refractive power measuring apparatuses) such as a refractometer that can measure the ocular refractive power of the subject's eye E. The present invention can also be applied to various ophthalmic apparatuses (other than ocular refractive power measuring apparatuses) that adjust the position of a part of the visual target projection optical system (light source, focusing lens, etc.) in accordance with the dioptric power of the subject, etc. [Explanation of symbols]

[0090] 1…Ophthalmology equipment 2. Base 3…Face support part 3a…Chin rest 3b…Forehead support 4. Driving mechanism 5…Measuring head 6...Display section 9...Control device 12...Observation optical system 12a…Objective lens 12b…Dichroic filter 12c…Half mirror 12d…Relay lens 12e…Dichroic filter 12f...Imaging lens 12g…Image sensor 12h…Kerato board 12i…Keratography light source 13…Z alignment optical system 13a…Alignment light source 13b…Projection lens 14…XY alignment optical system 14a…Alignment light source 14b…Projection lens 15…Target projection optical system 15a...Optotype display section 15e…Focusing lens 15f…Relay lens 15g...field lens 15i…Reflective mirror 15j…Dichroic filter 16...Measurement pattern projection optical system 16a…Reflector light source device 16b…Relay lens 16c…Cone prism 16d…Field lens 16e…Aperture ring 16f...perforated prism 16g…Rotary prism 17…Receiving optical system 17a…Field lens 17b…Reflective mirror 17c…Relay lens 17d…Focusing lens 17e…Reflective mirror 27...Interlocking movement mechanism 100...Pinhole plate 100a...pinhole 102...Laser diode 104...Optical scanning unit 106...Special lens 110...Lens switching device 110a...Lens E…Examined eye Ec…cornea Ef…fundus O1…main optical axis O2…optical axis O3…Optical axis O4…Optical axis

Claims

1. An ophthalmic apparatus for measuring an ocular refractive power of a subject's eye, a target projection optical system including at least a light beam emitting unit that emits a light beam of a fixation target and a lens through which the light beam of the fixation target passes, the target projection optical system projecting the light beam of the fixation target onto the subject's eye; a focal depth extending unit provided in the visual target projection optical system and configured to extend a focal depth of the visual target projection optical system; Equipped with An ophthalmic apparatus, in which the positions of the light beam emitting unit and the lens in the visual target projection optical system are fixed.

2. The ophthalmic apparatus according to claim 1 , wherein the focal depth extension unit limits a numerical aperture of the target projection optical system.

3. 3. The ophthalmic apparatus according to claim 2, wherein the focal depth extending section has a pinhole arranged on an optical path of the light beam of the fixation target and at a position conjugate with the pupil of the subject's eye.

4. the light beam emitting unit has a laser light source as a light source of the light beam of the fixation target, the target projection optical system has a light scanning unit that scans a light beam of the fixation target to be projected onto the subject's eye, The ophthalmic apparatus according to claim 2 , wherein the focal depth extending unit is the laser light source.

5. 2. The ophthalmic apparatus according to claim 1, wherein the focal depth extending section is a focal depth extending optical element or a multifocal optical element arranged at a position conjugate with the pupil of the subject's eye.

6. 6. The ophthalmic apparatus according to claim 1, wherein the target projection optical system diverges a light beam of the fixation target projected onto the subject's eye.

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