Ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system

Abstract

The present invention belongs to the field of fundus imaging technology and discloses an ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system, comprising: a spectroscopic module, a focusing module, a scanning module, a transmission lens group, an ellipsoidal reflector, and a detection module; wherein the center of the scanning module and the center of the transmission lens group are on the same optical axis A, the human eye pupil is located at the first focus of the ellipsoidal reflector, and the transmission lens group entrance pupil is located at the second focus of the ellipsoidal reflector; the transmission lens group includes a movable focusing lens for changing the position of the first image plane of light reflected from the human eye retina when moving along the optical axis A, thereby achieving clear images of the retinas of human eyes with different diopters. Without introducing a free-form surface, the present invention achieves ultra-wide-angle multi-wavelength confocal laser scanning fundus imaging with a single intraocular field of view angle of 200°, and a full-field optical resolution of 15μm. By moving the focusing lens, imaging compensation can be performed for human eyes with a diopters ranging from -15D to +15D.

Description

Technical Field

[0001] The present invention belongs to the technical field of fundus imaging, and more specifically, relates to an ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system. Background Art

[0002] Fundus imaging equipment has been widely used in the clinical diagnosis of fundus diseases. It can help doctors understand the fundus condition, detect lesions in fundus structures such as the retina and choroid, and provide guidance for the diagnosis of some systemic diseases such as hypertension and diabetes. The confocal scanning laser ophthalmoscope (cSLO) is an ophthalmic detection device that uses a narrow-band or broadband light source of a certain wavelength to continuously scan the retinal surface point by point, and then rearranges and analyzes the obtained two-dimensional data through a computer and reconstructs it into a two-dimensional image. Compared with traditional ophthalmoscopes, cSLO can block stray light before and after the focus through the confocal structure, thereby improving imaging resolution and image contrast. It has the advantages of not requiring mydriasis, low required illumination brightness, and high light collection efficiency.

[0003] Limited by pupil size, eye-lens distance, galvanometer vibration frequency, and scanning range, the field of view of ordinary cSLO is relatively small, reaching only 40°, covering only about 11% of the total retinal area. If fundus lesions occur in the periphery, it is easy to cause missed diagnosis. The field of view stitching method is usually used to expand the field of view of the system and achieve ultra-wide-angle fundus imaging. However, this method requires multiple photographs of the fundus in a single test and stitching of multiple images, which is a cumbersome operation. Summary of the Invention

[0004] In response to the above defects or improvement needs of the prior art, the present invention provides an ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system, the purpose of which is to achieve large-field, ultra-wide-angle, high-resolution fundus imaging through a single shot.

[0005] To achieve the above objectives, according to a first aspect of the present invention, there is provided an ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system, comprising:

[0006] Spectroscopic module, focusing module, scanning module, transmission mirror group, ellipsoidal reflector and detection module;

[0007] The laser light emitted by the light source passes through the spectroscopic module, the focusing module, the scanning module, the transmission mirror group and the ellipsoidal reflector in sequence along the first optical path, and then reaches the retina of the human eye through the pupil; the light reflected by the retina of the human eye passes through the ellipsoidal reflector, the transmission mirror group, the scanning module, the focusing module and the spectroscopic module in sequence along the second optical path, and is received by the detection module to form an image of the retina of the human eye;

[0008] The center of the scanning module and the center of the transmission mirror group are on the same optical axis A, the pupil of the human eye is located at the first focus of the ellipsoidal reflector, and the entrance pupil of the transmission mirror group is located at the second focus of the ellipsoidal reflector, so that the pupil of the human eye and the entrance pupil of the transmission mirror group form a conjugate relationship; the transmission mirror group includes a movable focusing lens, which is used to change the position of the first image plane of the light reflected by the human retina when moving along the optical axis A, so as to achieve clear images of the retinas of human eyes with different refractive powers.

[0009] Furthermore, the curvature radius of the ellipsoidal reflector is 80-85 mm, the conic coefficient is -0.2-0, and the vertical distance between the first focus and the second focus is 30-40 mm.

[0010] Furthermore, the transmission lens group includes, in sequence along the first optical path direction: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens; wherein the fifth lens is the focusing lens;

[0011] The sixth, seventh, and eighth lenses are used to correct the aberration of light reflected within a 200° field of view of the retina of the human eye;

[0012] The fifth lens acts as the focusing lens and moves between the fourth lens and the sixth lens along the optical axis A to change the position of the first image plane of the light reflected from the retina of the human eye, thereby achieving a clear image of the retina of the human eye with different refractive powers;

[0013] The first lens, the second lens, and the third lens are used to correct the aberration of the first image plane, and adjust the angle between the light of the first image plane and the optical axis A so that the light of the first image plane is parallel to the optical axis A, and compress the line width of the light so that the light after line compression is adapted to the size of the scanning module.

[0014] Furthermore, the first lens is a cemented lens, wherein the first surface along the first optical path is convex with a curvature radius of -130 to -140 mm, the second surface is concave with a curvature radius of 20 to 25 mm, the third surface is concave with a curvature radius of 30 to 40 mm, the center thickness between the first surface and the second surface is 13 to 14 mm, and the center thickness between the second surface and the third surface is 6 to 7 mm;

[0015] The first surface of the second lens along the first optical path is convex, with a curvature radius of -1310 to -1320 mm, and the second surface is convex, with a curvature radius of -70 to -80 mm, and the center thickness between the two surfaces is 25 to 30 mm;

[0016] The first surface of the third lens along the first optical path is convex with a curvature radius of -250 to -260 mm, the second surface is concave with a curvature radius of 320 to 330 mm, and the center thickness between the two surfaces is 25 to 30 mm;

[0017] The first surface of the fourth lens along the first optical path is convex, with a curvature radius of -80 to -90 mm, the second surface is convex, with a curvature radius of -110 to -120 mm, and the center thickness between the two surfaces is 30 to 35 mm;

[0018] The first surface of the fifth lens along the first optical path is concave with a curvature radius of 80 to 90 mm, the second surface is concave with a curvature radius of 40 to 50 mm, and the center thickness between the two surfaces is 30 to 35 mm.

[0019] The first surface of the sixth lens along the first optical path is convex with a curvature radius of -60 to -70 mm, the second surface is concave with a curvature radius of 40 to 50 mm, and the center thickness between the two surfaces is 6 to 7 mm;

[0020] The first surface of the seventh lens along the first optical path is convex, with a curvature radius of -10 to -15 mm, the second surface is convex, with a curvature radius of -30 to -35 mm, and the center thickness between the two surfaces is 7 to 8 mm;

[0021] The first surface of the eighth lens along the first optical path is concave with a curvature radius of 1500-1520 mm, the second surface is concave with a curvature radius of 1530-1540 mm, and the center thickness between the two surfaces is 13-14 mm.

[0022] Furthermore, the gap between the second lens and the first lens is 100-110 mm; the gap between the second lens and the third lens is 90-100 mm; the gap between the third lens and the fourth lens is 130-140 mm; the gap between the fourth lens and the sixth lens is 60-70 mm; the fifth lens acts as the focusing lens and moves between the fourth lens and the sixth lens according to the refractive power of the human eye; the gap between the sixth lens and the seventh lens is 1-2 mm; and the gap between the seventh lens and the eighth lens is 4-5 mm.

[0023] Furthermore, the aperture of each lens from the first lens to the eighth lens is less than 70 mm.

[0024] Furthermore, it also includes a light source module for emitting laser as a light source; the light source is a single-wavelength light source or a multi-wavelength light source; when the light source is a multi-wavelength light source, before the lasers of different wavelengths enter the spectroscopic module, it also includes a beam combiner for combining the lasers of different wavelengths.

[0025] Furthermore, when the light source is a multi-wavelength light source, the focusing module includes a plano-convex lens, a biconcave lens, and a biconvex lens in sequence along the first light path direction to correct the chromatic aberration introduced by the multi-wavelength.

[0026] Furthermore, the spectroscopic module is a spectroscope or a spectroscope group; and the scanning module is a two-dimensional galvanometer.

[0027] Furthermore, the detection module includes a detector and a host computer; the detector is used to convert the received optical signal into an electrical signal and transmit it to the host computer; the host computer performs human retinal imaging based on the electrical signal.

[0028] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0029] (1) The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system of the present invention is configured such that the pupil of the human eye is set at the first focus of the ellipsoidal reflector and the entrance pupil of the transmission mirror group is set at the second focus of the ellipsoidal reflector, so that the pupil of the human eye and the entrance pupil of the transmission mirror group form a conjugate relationship. In this way, by utilizing the characteristic that light from one focus of the ellipsoid will inevitably converge to the other focus, all light reflected from the retina through the pupil of the human eye is converged to the entrance pupil of the transmission mirror group. Then, by moving the movable focusing lens in the transmission mirror group along the optical axis A, the position of the first image plane of the light reflected from the retina of the human eye is changed to change the clarity of the imaging of the detection module, so that the transmission mirror group can correct the light of a large field of view, thereby realizing large-field ultra-wide-angle clear imaging of the retina of the human eye with different refractive powers in a single shot.

[0030] At the same time, the first light path (incident light path) and the second light path (reflected light path) pass through the same element to form a confocal structure, which can improve imaging resolution and image contrast, and has the advantages of no need for pupil dilation, low required illumination brightness, and high light collection efficiency.

[0031] (2) Furthermore, when designing a large field of view with a viewing angle of 200° in the eye, it is considered that the aberration of a single ellipsoid with a large field of view is large, especially the light at the upper and lower edges of the ellipsoid (corresponding to the retinal object height ±11.98mm) will have an aberration difference at the second focus. Usually, the asymmetry of the free-form surface can be used to solve it. However, the free-form surface has defects such as difficulty in processing and high processing cost. In order to achieve the correction of aberration without using a free-form surface and in combination with the transmission lens group of the present invention, the present invention uses the ellipsoidal reflection to correct the aberration. The design of the mirror curvature radius, cone coefficient, and the distance between the two focal points ensures that light rays at a retinal object height of -10mm to -10.1mm can pass through the optical axis A of the transmission lens assembly (coinciding with the optical axis) when they emerge from the second focal point of the ellipsoidal reflector, while light rays at 0mm in the center of the field of view do not coincide with the optical axis A. In this way, light rays across the entire field of view pass through the transmission lens assembly asymmetrically. This asymmetrical field of view design helps the transmission lens assembly compensate for the aberration difference in the field of view light rays at the upper and lower edges of the single ellipsoidal reflector without the need for a free-form surface.

[0032] (3) Preferably, in order to achieve a large field of view aberration correction of 200° in the eye, the transmission lens group of the present invention includes eight lenses along the first optical path direction. Since a single ellipsoidal reflector has a large aberration under a large field of view of 200° in the eye, the sixth lens, the seventh lens and the eighth lens are used to perform aberration correction on the reflected light within the 200° field of view of the human eye retina, thereby achieving a large field of view aberration correction. The fifth lens acts as a focusing lens and moves along the optical axis A between the fourth lens and the sixth lens to change the position of the first image plane of the light reflected from the human eye retina, thereby achieving aberration correction of different human eye refractive powers; the first lens, the second lens and the third lens are used to correct the aberration of the first image plane and adjust the angle between the light of the first image plane and the optical axis A so that the light of the first image plane is parallel to the optical axis A, and the line width of the light is compressed so that the light after line compression is compatible with the size of the scanning module 4.

[0033] (4) As a preference, by designing the lens shape of the transmission lens group, combining the setting of parameters such as the curvature radius and the center thickness, and coordinating the transmission lens group with the ellipsoidal reflector, it is possible to achieve large field of view aberration correction and human eye diopter aberration correction.

[0034] (5) Preferably, the imaging effect is further improved by limiting the gaps between the lenses of the transmission lens group. By moving the fifth lens (focusing lens) between the fourth lens and the sixth lens, the system can perform imaging compensation for the human eye with a diopter range of -15D to +15D.

[0035] (6) As a preference, the design of the aperture of each lens and the constraints on the thickness of the lens facilitate processing.

[0036] In summary, the present invention leverages the properties of the ellipsoid to achieve conjugation between the human pupil and the entrance pupil of the transmission lens assembly. Without introducing free-form surfaces, it achieves ultra-wide-angle, multi-wavelength confocal laser scanning fundus imaging with a single 135° extraocular field of view (200° intraocular field of view), achieving a full-field optical resolution of 15 μm. Furthermore, by moving the focusing lens in the transmission lens assembly, imaging compensation can be performed for human eyes with a diopter range of -15D to +15D. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of the structure of an ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system provided by an embodiment of the present invention;

[0038] Figure 2 Schematic diagram of the structure of the ellipsoidal reflector and transmission mirror assembly provided by an embodiment of the present invention;

[0039] Figure 3 Schematic diagram of adjustment of the focusing lens in the transmission lens assembly;

[0040] Figure 4 This is a full-field spot diagram at a wavelength of 488 nm in an embodiment of the present invention;

[0041] Figure 5 This is a full-field spot diagram at a wavelength of 520 nm in an embodiment of the present invention;

[0042] Figure 6 This is a full-field spot diagram at a wavelength of 635 nm in an embodiment of the present invention;

[0043] Figure 7 This is a full-field spot diagram at a wavelength of 785 nm in an embodiment of the present invention.

[0044] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0045] 1-light source module, 2-spectroscopy module, 3-focusing module, 4-scanning module, 5-transmission lens group, 6-ellipsoidal reflector, 7-human eye, 8-detector, 9-host computer, 501-second focus, 502-focusing lens, 701-first focus. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0047] In the present invention, the terms "first", "second", etc. in the present invention and the accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0048] like Figure 1 As shown, the ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system in an embodiment of the present invention includes: a light source module 1, a spectroscopic module 2, a focusing module 3, a scanning module 4, a transmission lens group 5, an ellipsoidal reflector 6 and a detection module.

[0049] The laser emitted by the light source module 1 passes through the spectroscopic module 2, the focusing module 3, the scanning module 4, the transmission mirror group 5 and the ellipsoidal reflector 6 in sequence along the first optical path, and then reaches the retina of the human eye through the pupil; the light reflected by the retina of the human eye passes through the ellipsoidal reflector 6, the transmission mirror group 5, the scanning module 4, the focusing module 3 and the spectroscopic module 2 in sequence along the second optical path, and then enters the detection module, which is used to perform imaging based on the reflected light received from the human eye 7.

[0050] The center of the scanning module 4 and the center of the transmission lens group 5 are on the same optical axis A, the human eye pupil is located at the first focus of the ellipsoidal reflector 6, and the entrance pupil of the transmission lens group 5 is located at the second focus of the ellipsoidal reflector 6, so that the human eye pupil and the entrance pupil of the transmission lens group form a conjugate relationship; the transmission lens group 5 includes a movable focusing lens 502, which is used to change the position of the first image plane of the light reflected from the human eye retina when moving along the optical axis A, so as to change the clarity of the imaging of the detection module and realize clear imaging of the retina of the human eye with different refractive powers.

[0051] The light source module 1 is used to emit laser as a light source to illuminate the fundus. The light source module 1 can be selected from lasers but is not limited to lasers. Figure 1 The light source module 1 in the figure shows only one light source, but the actual light source module 1 can be a single wavelength light source or a multi-wavelength light source. When a multi-wavelength light source is used, lasers of different wavelengths are usually combined by a beam combiner to form a beam of light, which enters the spectrometer module 2. In the embodiment of the present invention,

[0052] In the embodiment of the present invention, the light source module 1 is a multi-wavelength light source with emission wavelengths of 488 nm, 520 nm, 635 nm, and 785 nm. The light is combined by a beam combiner to form a beam and then enters the spectrometer module 2 .

[0053] The light splitting module 2 is used to receive light from the light source module 1 and control a certain proportion of the light to pass through the light splitting module 2 and then through the focusing module 3 to the scanning module 4. The light splitting module 2 can be a beam splitter or a beam splitter group, and the beam splitter can be a cube beam splitter or a flat beam splitter according to actual needs. In the embodiment of the present invention, the light splitting module 2 is a beam splitter.

[0054] The focusing module 3 is used to converge the light transmitted through the spectrometer module 2 to the scanning module 4. It only focuses the light and does not provide additional correction for aberrations. In one embodiment, the focusing module includes a plano-convex lens, a biconcave lens, and a biconvex lens along the first optical path, which can correct for chromatic aberration introduced by multiple wavelengths. In other embodiments, the focusing module 3 can also be composed of optical fibers and fiber couplers.

[0055] Scanning module 4 receives the light focused by focusing module 3. It uses a two-dimensional galvanometer to scan the focused light and redirect it. The center of the galvanometer and the center of the transmission lens assembly 5 are on the same optical axis A. Passing through the two-dimensional galvanometer, light rays with different field angles are emitted in the same direction, achieving point scanning.

[0056] The transmission lens assembly 5 is used to receive light passing through the scanning module 4 and transmit it to the ellipsoidal reflector 6. The transmission lens assembly 5 contains a movable focusing lens 502 that can move along the optical axis A. The ellipsoidal reflector 6 has two focal points: a first focal point 701 and a second focal point 501. The human eye pupil is located at the first focal point 701, and the entrance pupil of the transmission lens assembly 5 is located at the second focal point 501. The two form a conjugate relationship, which facilitates the correction of aberrations by the transmission lens assembly 5. Specifically, light emitted from the transmission lens assembly 5 passes through the second focal point 501 of the ellipsoidal reflector 6 and is then reflected by the ellipsoidal reflector 6 to the human eye pupil at its first focal point 701, illuminating the retina. Light reflected from the retina passes through the first focal point 701 of the ellipsoidal reflector 6 and is then reflected by the ellipsoidal reflector 6 to its second focal point 501. All light enters the transmission lens assembly 5 through the entrance pupil of the transmission lens assembly 5, passes through the scanning module 4, the focusing module 3, and the spectrometer module 2, and is incident on the detection module for imaging. In this process, by moving the focusing lens 502 along the optical axis A, the position of the first image plane of the light reflected from the retina of the human eye is changed, so as to change the clarity of the imaging of the detection module and realize the correction of the diopter aberration of the human eye.

[0057] In an embodiment of the present invention, the detection module includes a detector 8 and a host computer 9. The detector 8 can be a single-pixel detector, which is used to convert the received light signal into an electrical signal and transmit it to the host computer 9, which performs algorithm processing and reconstructs the fundus image. Figure 1 Only one single-pixel detector is shown in the figure. In actual use, after the reflected light is split by the spectrometer module 2, light of different wavelengths reaches different single-pixel detectors for imaging.

[0058] The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system of the present invention is configured such that the pupil of the human eye is disposed at the first focus of the ellipsoidal reflector 6 and the entrance pupil of the transmission lens group 5 is disposed at the second focus of the ellipsoidal reflector 6, so that the pupil of the human eye and the entrance pupil of the transmission lens group form a conjugate relationship. In this way, by utilizing the characteristic that light from one focus of the ellipsoid will inevitably converge to the other focus, all light reflected from the retina and emitted through the pupil of the human eye is converged to the entrance pupil of the transmission lens group 5. Then, by moving the movable focusing lens 502 in the transmission lens group 5 along the optical axis A, the position of the first image plane of the light reflected from the retina of the human eye is changed to change the clarity of the imaging of the detection module, so that the transmission lens group 5 can correct the light of a large field of view, thereby achieving large-field ultra-wide-angle clear imaging of the retina of the human eye with different refractive powers in a single shot.

[0059] At the same time, the first light path (incident light path) and the second light path (reflected light path) pass through the same element to form a confocal structure, which can improve imaging resolution and image contrast, and has the advantages of no need for pupil dilation, low required illumination brightness, and high light collection efficiency.

[0060] As a further design of the present invention, when designing a large field of view with a 200° field of view angle within the eye, it is taken into account that the aberration of a single ellipsoid with a large field of view is large, especially the light at the upper and lower edges of the ellipsoid (corresponding to the retinal object height of ±11.98 mm) will have an aberration difference at the second focus. This can usually be solved by utilizing the asymmetry of a free-form surface. However, free-form surfaces have defects such as difficulty in processing and high processing costs. In order to achieve aberration correction without using a free-form surface and in combination with the transmission lens assembly 5 of the present invention, the embodiment of the present invention solves this technical problem by designing the curvature radius, cone coefficient and distance between the two focal points of the ellipsoidal reflector 6.

[0061] Specifically, the radius of curvature of the ellipsoidal reflector 6 is 80 to 85 mm, the cone coefficient is -0.2 to 0, and the vertical distance between the first focus and the second focus is 30 to 40 mm. This allows the light at a retinal object height of -10 mm to -10.1 mm (preferably the light at -10.08 mm) to pass through the optical axis A of the transmission lens group 5 (coinciding with the optical axis) when it emerges from the second focus of the ellipsoidal reflector 6, while the light at 0 mm in the center of the non-field of view coincides with the optical axis, so that the light of the entire field of view passes through the transmission lens group asymmetrically. This asymmetric field of view design is beneficial for the transmission lens group to compensate for the aberration difference between the light in the upper and lower edges of the field of view of the single ellipsoidal reflector.

[0062] As a further design of the present invention, in order to achieve a large field of view aberration correction of 200° in the eye, the transmission lens group 5 in the embodiment of the present invention includes, along the first optical path direction,: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens; wherein the fifth lens is a focusing lens 502.

[0063] Since the single-piece ellipsoidal reflector 6 has large aberrations under a large field of view of 200° in the eye, in the embodiment of the present invention, the sixth lens, the seventh lens and the eighth lens are used together to correct the aberrations of the reflected light within the 200° field of view of the human eye's retina, thereby achieving large-field aberration correction.

[0064] The fifth lens acts as a focusing lens and moves along the optical axis A between the fourth and sixth lenses, changing the position of the first image plane of the light reflected from the retina of the human eye to achieve aberration correction for different human eye diopters.

[0065] The first lens, the second lens and the third lens are used together to correct the aberration of the first image plane, and adjust the angle between the light of the first image plane and the optical axis A so that the light of the first image plane is parallel to the optical axis A, and compress the line width of the light so that the light after line compression is adapted to the size of the scanning module 4.

[0066] At the same time, the design of the sixth lens, the seventh lens, and the eighth lens not only corrects aberrations but also makes the width of each field of view light equal, making it easier for subsequent lenses to perform aberration and angle correction on the entire field of view at the same time.

[0067] As a preferred implementation, the first lens is a cemented lens, the first surface along the first optical path is convex, the radius of curvature is set to -130 to -140 mm, the second surface is concave relative to the first surface, the radius of curvature is set to 20 to 25 mm, the third surface is concave, the radius of curvature is set to 30 to 40 mm, the center thickness between the first surface and the second surface is 13 to 14 mm, and the center thickness between the second surface and the third surface is 6 to 7 mm;

[0068] The first surface of the second lens along the first optical path is convex, with a curvature radius of -1310 to -1320 mm, and the second surface is convex, with a curvature radius of -70 to -80 mm, and the center thickness between the two surfaces is 25 to 30 mm;

[0069] The first surface of the third lens along the first optical path is convex, with a curvature radius of -250 to -260 mm, and the second surface is concave, with a curvature radius of 320 to 330 mm. The center thickness between the two surfaces is 25 to 30 mm.

[0070] The first surface of the fourth lens along the first optical path is a convex surface with a curvature radius of -80 to -90 mm, the second surface is a convex surface with a curvature radius of -110 to -120 mm, and the center thickness between the two surfaces is 30 to 35 mm;

[0071] The fifth lens is a movable focusing lens, wherein the first surface along the first optical path is a concave surface with a curvature radius of 80 to 90 mm, the second surface is a concave surface with a curvature radius of 40 to 50 mm, and the center thickness between the two surfaces is 30 to 35 mm;

[0072] The first surface of the sixth lens along the first optical path is convex, with a curvature radius of -60 to -70 mm, and the second surface is concave, with a curvature radius of 40 to 50 mm. The center thickness between the two surfaces is 6 to 7 mm.

[0073] The first surface of the seventh lens along the first optical path is a convex surface with a curvature radius of -10 to -15 mm, the second surface is a convex surface with a curvature radius of -30 to -35 mm, and the center thickness between the two surfaces is 7 to 8 mm;

[0074] The first surface of the eighth lens along the first optical path is concave, and the radius of curvature is set to 1500-1520 mm. The second surface is concave, and the radius of curvature is set to 1530-1540 mm. The center thickness between the two surfaces is 13-14 mm. The range values ​​in the embodiment of the present invention all include the endpoint values.

[0075] By designing the shape of the lens of the transmission mirror group, combining the setting of parameters such as the curvature radius and the center thickness, and coordinating the transmission mirror group with the ellipsoidal reflector, large field of view aberration correction and human eye refractive aberration correction can be achieved.

[0076] As a preferred implementation, the gap between the second lens and the first lens is 100-110 mm; the gap between the second lens and the third lens is 90-100 mm; the gap between the third lens and the fourth lens is 130-140 mm; the gap between the fourth lens and the sixth lens is 60-70 mm; the fifth lens acts as a focusing lens and moves between the fourth lens and the sixth lens according to the refractive power of the human eye; the gap between the sixth lens and the seventh lens is 1-2 mm; and the gap between the seventh lens and the eighth lens is 4-5 mm.

[0077] By limiting the gaps between the lenses of the transmission lens assembly, the imaging effect is further improved. By moving the fifth lens (focusing lens) between the fourth and sixth lenses, the system can compensate for the human eye's diopter within the range of -15D to +15D.

[0078] As a preferred implementation, in order to facilitate processing, the aperture (diameter) of each lens is less than 70 mm, and the thickness of each lens is ≤35 mm.

[0079] like Figure 2The figure shows a schematic diagram of the structure of the ellipsoidal reflector 6 and the transmission lens group 5 in the fundus imaging system of the embodiment of the present invention. After the incident light of different wavelengths passes through the transmission lens group 5 and the ellipsoidal reflector 6, large field of view aberration correction and human eye diopter aberration correction can be achieved. As can be seen from the figure, unlike the conventional design method in which the light at the center of the field of view (retinal object plane height 0mm) passes through the optical axis center A of the transmission lens group, and the upper and lower edge field of view light passes through the transmission lens group symmetrically, in the embodiment of the present invention, by setting the curvature radius, cone coefficient and the distance between the two focal points of the ellipsoidal reflector 6, the light at the retinal object plane height of -10.08mm can be controlled to pass through the optical axis center of the transmission lens group (rather than the light at the field of view center 0mm), and the light of the entire field of view passes through the transmission lens group asymmetrically, which is beneficial for the transmission lens group to compensate for the aberration difference of the upper and lower edge field of view light of the single ellipsoidal reflector.

[0080] When performing diopter compensation, the total length of the transmission lens group 5 remains unchanged, and only the focusing lens 502 moves along the optical axis between the fourth lens and the sixth lens to achieve imaging compensation for the human eye with a diopter within the range of -15D to +15D, such as Figure 3 shown.

[0081] The imaging effect of the system of the present invention is described below with reference to specific examples.

[0082] The designed ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system is used to perform full-field imaging with light sources emitting lasers with wavelengths of 488nm, 520nm, 635nm, and 785nm. Specifically, the light source module emits lasers with wavelengths of 488nm, 520nm, 635nm, and 785nm, which are reflected by the beam splitter along the first optical path and enter the focusing module, then pass through the scanning module to enter the transmission mirror group and the ellipsoidal reflector, and then reach the retina of the human eye through the pupil; the light reflected from the fundus of the human eye passes through the ellipsoidal reflector, the transmission mirror group, the scanning module, and the focusing module in sequence along the second optical path, and is incident on the beam splitter, and then passes through the beam splitter to the detection module, which converts the light signal into a digital image. The full-field point array diagram is shown in the figure below. Figures 4 to 7 As shown, Figure 4 This is the full field of view spot diagram at a wavelength of 488nm. Figure 5 This is the full field of view spot diagram at a wavelength of 520nm. Figure 6 This is the full field of view spot diagram at a wavelength of 635nm. Figure 7 This is the full-field spot diagram at a wavelength of 785nm.

[0083] By Figures 4 to 7As shown, 10 fields of view were obtained at each wavelength. Fields of view 1 to 10 correspond to an object plane extending from 11.98 mm to -11.98 mm, corresponding to an extraocular field of view angle of 135° (an intraocular field of view angle of 200°). The RMS (spot diagram, used to reflect aberrations) radius for each field of view is shown in Table 1 below:

[0084] Table 1 RMS radius corresponding to fields of view 1 to 10

[0085] Field of View 1 Field of View 2 Field of View 3 Field of View 4 Field of View 5 8.966μm 7.248μm 5.470μm 10.740μm 11.986μm Field of view 6 Field of view 7 Field of view 8 Field of view 9 Field of view 10 14.995μm 12.118μm 6.166μm 4.85μm 9.520μm

[0086] As can be seen from Table 1, the aberration of imaging at an intraocular field angle of 200° is relatively small. Figures 4 to 7 It can be seen that only a single ellipsoidal reflector, combined with a transmission lens assembly, achieves clear imaging with a single 135° field of view outside the eye (200° field of view inside the eye), and a full-field optical resolution of 15μm. The entire system combines the advantages of ultra-wide angle, high resolution, and no mydriasis.

[0087] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system, characterized in that: include: A light splitting module (2), a light focusing module (3), a scanning module (4), a transmission mirror group (5), an ellipsoidal reflector (6), and a detection module; The laser light emitted by the light source passes through the light splitting module (2), the light focusing module (3), the scanning module (4), the transmission mirror group (5) and the ellipsoidal reflector (6) in sequence along the first optical path, and then reaches the retina of the human eye through the pupil; the light reflected by the retina of the human eye passes through the ellipsoidal reflector (6), the light transmission mirror group (5), the scanning module (4), the light focusing module (3) and the light splitting module (2) in sequence along the second optical path, and then is received by the detection module and forms an image of the retina of the human eye; The center of the scanning module (4) and the center of the transmission mirror group (5) are on the same optical axis A, the pupil of the human eye is located at the first focus of the ellipsoidal reflector (6), and the entrance pupil of the transmission mirror group (5) is located at the second focus of the ellipsoidal reflector (6), so that the pupil of the human eye and the entrance pupil of the transmission mirror group (5) form a conjugate relationship; the transmission mirror group (5) includes a movable focusing lens for changing the position of the first image plane of the light reflected by the retina of the human eye when moving along the optical axis A, so as to achieve a clear image of the retina of the human eye with different diopters; The transmission lens group (5) includes, in sequence along the first light path direction: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens; wherein the fifth lens is the focusing lens; The sixth, seventh, and eighth lenses are used to correct the aberration of light reflected within a 200° field of view of the retina of the human eye; The fifth lens acts as the focusing lens and moves between the fourth lens and the sixth lens along the optical axis A to change the position of the first image plane of the light reflected from the retina of the human eye, thereby achieving a clear image of the retina of the human eye with different refractive powers; The first lens, the second lens and the third lens are used to correct the aberration of the first image plane, and at the same time adjust the angle between the light of the first image plane and the optical axis A so that the light of the first image plane is parallel to the optical axis A, and compress the line width of the light so that the light after line compression is adapted to the size of the scanning module (4); The first lens is a cemented lens, the first surface along the first optical path is convex with a curvature radius of -130 to -140 mm, the second surface is concave with a curvature radius of 20 to 25 mm, the third surface is concave with a curvature radius of 30 to 40 mm, the center thickness between the first and second surfaces is 13 to 14 mm, and the center thickness between the second and third surfaces is 6 to 7 mm; The first surface of the second lens along the first optical path is convex, with a curvature radius of -1310 to -1320 mm, and the second surface is convex, with a curvature radius of -70 to -80 mm, and the center thickness between the two surfaces is 25 to 30 mm; The first surface of the third lens along the first optical path is convex with a curvature radius of -250 to -260 mm, the second surface is concave with a curvature radius of 320 to 330 mm, and the center thickness between the two surfaces is 25 to 30 mm; The first surface of the fourth lens along the first optical path is convex, with a curvature radius of -80 to -90 mm, and the second surface is convex, with a curvature radius of -110 to -120 mm, and the center thickness between the two surfaces is 30 to 35 mm; The first surface of the fifth lens along the first optical path is concave with a curvature radius of 80 to 90 mm, the second surface is concave with a curvature radius of 40 to 50 mm, and the center thickness between the two surfaces is 30 to 35 mm. The first surface of the sixth lens along the first optical path is convex with a curvature radius of -60 to -70 mm, the second surface is concave with a curvature radius of 40 to 50 mm, and the center thickness between the two surfaces is 6 to 7 mm; The first surface of the seventh lens along the first optical path is convex, with a curvature radius of -10 to -15 mm, and the second surface is convex, with a curvature radius of -30 to -35 mm. The center thickness between the two surfaces is 7 to 8 mm. The first surface of the eighth lens along the first optical path is concave with a curvature radius of 1500-1520 mm, the second surface is concave with a curvature radius of 1530-1540 mm, and the center thickness between the two surfaces is 13-14 mm.

2. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 1, characterized in that: The curvature radius of the ellipsoidal reflector (6) is 80-85 mm, the cone coefficient is -0.2-0, and the vertical distance between the first focus and the second focus is 30-40 mm.

3. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 1, characterized in that: The gap between the second lens and the first lens is 100-110 mm; the gap between the second lens and the third lens is 90-100 mm; the gap between the third lens and the fourth lens is 130-140 mm; the gap between the fourth lens and the sixth lens is 60-70 mm; the fifth lens acts as the focusing lens and moves between the fourth lens and the sixth lens according to the refractive power of the human eye; the gap between the sixth lens and the seventh lens is 1-2 mm; and the gap between the seventh lens and the eighth lens is 4-5 mm.

4. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 3, characterized in that: The aperture of each lens from the first lens to the eighth lens is less than 70 mm.

5. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 1, characterized in that: It also includes a light source module (1) for emitting laser light as a light source; the light source is a single-wavelength light source or a multi-wavelength light source; when the light source is a multi-wavelength light source, it also includes a beam combiner for combining the laser light of different wavelengths before the laser light of different wavelengths enters the light splitting module (2).

6. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 5, characterized in that: When the light source is a multi-wavelength light source, the focusing module (3) comprises a plano-convex lens, a biconcave lens, and a biconvex lens in sequence along the first light path direction to correct the chromatic aberration introduced by the multi-wavelengths.

7. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 1, characterized in that: The light splitting module (2) is a light splitter or a light splitter group; the scanning module (4) is a two-dimensional galvanometer.

8. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 1, characterized in that: The detection module comprises a detector (8) and a host computer (9); the detector (8) is used to convert a received optical signal into an electrical signal and transmit the signal to the host computer (9); the host computer (9) performs human eye retinal imaging based on the electrical signal.

Images