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

Abstract

The invention belongs to the technical field of fundus imaging, and discloses an ultra-wide-angle ellipsoid confocal laser scanning fundus imaging system, which comprises a light splitting module, a light condensing module, a scanning module, a transmitting mirror group, an ellipsoid reflector and a detection module, wherein the center of the scanning module and the center of the transmitting mirror group are located 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 transmitting mirror group is located at the second focus of the ellipsoidal reflector; and the transmitting lens group comprises a movable focusing lens and is used for changing the position of a first image surface of light reflected by the retina of the human eyes when moving along the optical axis A so as to realize clear imaging of the retina of the human eyes with different diopters. Under the condition that a free-form surface is not introduced, ultra-wide-angle multi-wavelength confocal laser scanning fundus imaging with the single intraocular field angle of 200 degrees is achieved, and the full-field optical resolution reaches 15 micrometers. And by moving the focusing lens, imaging compensation can be carried out on human eyes with diopters of-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, check for lesions in fundus structures such as the retina and choroid, and guide 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 no need for mydriasis, low required illumination brightness, and high light collection efficiency.

[0003] Limited by the size of the pupil, the distance between the eyeball and the lens, the vibration frequency and scanning range of the galvanometer, the field of view of ordinary cSLO is relatively small, only reaching 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 the stitching of multiple images, which is a cumbersome operation. Summary of the invention

[0004] In view of 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, which aims to achieve large-field ultra-wide-angle high-resolution fundus imaging through a single photo.

[0005] To achieve the above object, 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] A spectroscopic module, a focusing module, a scanning module, a transmission mirror set, an ellipsoidal reflector and a detection module;

[0007] The laser emitted by the light source passes through the light splitting module, the light focusing module, the scanning module, the transmission mirror group and the ellipsoidal reflector in sequence along the first optical path direction, 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 light focusing module and the light splitting module in sequence along the second optical path direction, and then 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 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 refractive powers.

[0009] Furthermore, the curvature radius of the ellipsoidal reflector 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.

[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 lens, the seventh lens and the eighth lens are used to correct the aberration of the reflected light within the 200° field angle of the human eye retina;

[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, so as to form a clear image of the retina of the human eye with different diopters;

[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, the first surface along the first optical path direction is a convex surface with a curvature radius of -130 to -140 mm, the second surface is a concave surface with a curvature radius of 20 to 25 mm, the third surface is a concave surface 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 a convex surface with a curvature radius of -1310 to -1320 mm, the second surface is a convex surface 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, and 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 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;

[0018] The first surface of the fifth lens 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;

[0019] The first surface of the sixth lens along the first optical path is a convex surface with a curvature radius of -60 to -70 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 6 to 7 mm;

[0020] 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;

[0021] The first surface of the eighth lens along the first optical path is a concave surface with a curvature radius of 1500-1520 mm, the second surface is a concave surface 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, which is used to emit 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-wavelengths.

[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 eye 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 ellipsoidal surface will definitely converge to another 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 achieving 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 mydriasis, low required illumination brightness, and high light collection efficiency.

[0031] (2) Further, 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 relatively 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. Usually, the asymmetry of the free-form surface can be used to solve this problem. However, the free-form surface has defects such as difficulty in processing and high processing cost. In order to achieve aberration correction without using a free-form surface and in combination with the transmission lens assembly of the present invention, the present invention uses an ellipsoidal reflection lens to correct the aberration. The design of the mirror curvature radius, cone coefficient and the distance between the two foci can make the light at the retinal object height of -10mm to -10.1mm pass through the optical axis A of the transmission lens group (coinciding with the optical axis) when it emerges from the second focus of the ellipsoidal reflector, while the light at the non-field center 0mm coincides with the optical axis A. In this way, 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 of the field of view light at the upper and lower edges of the single ellipsoidal reflector without using a free-form surface.

[0032] (3) Preferably, in order to achieve a large field of view aberration correction of 200° field of view 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 in the present invention jointly correct the aberration of the reflected light within the 200° field of view of the human eye retina, that is, to achieve a large field of view aberration correction. The fifth lens moves along the optical axis A between the fourth lens and the sixth lens as a focusing lens, changes the position of the first image plane of the reflected light from the human eye retina, and achieves aberration correction of different human eye diopters; the first lens, the second lens and the third lens jointly 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 compresses the line width of the light, so that the light after line compression is compatible with the size of the scanning module 4.

[0033] (4) As a preferred embodiment, through the design of the lens shape of the transmission lens group, combined with the setting of parameters such as the curvature radius and the center thickness, and the coordination of the transmission lens group with the ellipsoidal reflector, large field of view aberration correction and human eye diopter aberration correction can be achieved.

[0034] (5) As a preferred embodiment, the imaging effect is further improved by limiting the gap 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 human eyes with a diopter ranging from -15D to +15D.

[0035] (6) Preferably, the aperture of each lens is designed and the thickness of the lens is restricted to facilitate processing.

[0036] In summary, the present invention utilizes the characteristics of the ellipsoidal surface to achieve the conjugation between the pupil of the human eye and the entrance pupil of the transmission mirror set, and realizes ultra-wide-angle multi-wavelength confocal laser scanning fundus imaging with a single extraocular field of view angle of 135° (intraocular field of view angle of 200°) without introducing a free-form surface, and the full-field optical resolution reaches 15um. At the same time, by moving the focusing lens in the transmission mirror set, imaging compensation can be performed for human eyes with a diopter 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 is a schematic structural diagram of an ellipsoidal reflector and a transmission mirror assembly provided by an embodiment of the present invention;

[0039] Figure 3 It is a schematic diagram of adjusting 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 It 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 purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain 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 can 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, but 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 the 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 direction, 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 direction, and then enters the detection module, which is used to perform imaging based on the received reflected light generated by 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 pupil of the human eye 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 pupil of the human eye 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 by the retina of the human eye 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 a laser but is not limited to a laser. 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 into a beam by a beam combiner and enter the light splitting 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 488nm, 520nm, 635nm and 785nm. The light is combined into a beam by a beam combiner and then enters the light splitting module 2.

[0053] The light splitting module 2 is used to receive the light from the light source module 1, and control the light to pass through the light splitting module 2 in a certain proportion 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 can be selected according to actual needs. The beam splitter can be a cubic beam splitter or a flat beam splitter. In the embodiment of the present invention, the light splitting module 2 is a beam splitter.

[0054] The focusing module 3 is used to focus the transmitted light passing through the light splitting module 2 to the scanning module 4; it only focuses the light and does not perform additional correction for aberration. In one specific embodiment, the focusing module includes a plano-convex lens, a biconcave lens, and a biconvex lens in sequence along the first optical path direction, which can correct the chromatic aberration introduced by multiple wavelengths. In other embodiments, the focusing module 3 can also be composed of an optical fiber and an optical fiber coupler.

[0055] The scanning module 4 receives the light focused by the focusing module 3; the scanning module uses a two-dimensional galvanometer to perform point scanning on the focused light and change the direction of the light; the center of the galvanometer and the center of the transmission lens group 5 are on the same optical axis A. After passing through the two-dimensional galvanometer, light with different field angles will be emitted in the same direction to achieve point scanning.

[0056] The transmission lens group 5 is used to receive the light passing through the scanning module 4 and transmit it to the ellipsoidal reflector 6. The transmission lens group 5 contains a movable focusing lens 502, which can move along the optical axis A. The ellipsoidal reflector 6 has two focal points, namely a first focal point 701 and a second focal point 501. The pupil of the human eye is located at the first focal point 701, and the entrance pupil of the transmission lens group 5 is located at the second focal point 501. The two form a conjugate relationship, which is convenient for the transmission lens group 5 to correct aberrations. Specifically, the light emitted through the transmission lens group 5 passes through the second focal point 501 of the ellipsoidal reflector 6 and is reflected by the ellipsoidal reflector 6 to the pupil of the human eye at its first focal point 701, illuminating the retina. The retinal reflected light passes through the first focal point 701 of the ellipsoidal reflector 6 and is reflected by the ellipsoidal reflector 6 to its second focal point 501. All the light enters the transmission lens group 5 through the entrance pupil of the transmission lens group 5, passes through the scanning module 4, the focusing module 3 and the light splitting module 2 in sequence, 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 to change the clarity of the imaging of the detection module, thereby achieving the correction of the diopter aberration of the human eye.

[0057] In the embodiment of the present invention, the detection module includes a detector 8 and a host computer 9. The detector 8 may be a single-pixel detector for converting received optical signals into electrical signals and transmitting them to the host computer 9, which performs algorithm processing to reconstruct fundus images. 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 sets the pupil of the human eye at the first focus of the ellipsoidal reflector 6 and sets the entrance pupil of the transmission mirror group 5 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 form a conjugate relationship. In this way, by utilizing the characteristic that light from one focus of the ellipsoid will definitely converge to another 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 5, and then by moving the movable focusing lens 502 in the transmission mirror 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 mirror 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 mydriasis, 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 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 ±11.98 mm) will have an aberration difference at the second focus, which can usually be solved by utilizing the asymmetry of the free-form surface. However, the free-form surface has defects such as difficulty in processing and high processing cost. In order to achieve aberration correction without using a free-form surface and in conjunction with the transmission lens group 5 of the present invention, the present invention solves this technical problem by designing the curvature radius, cone coefficient and distance between the two foci of the ellipsoidal reflector 6 in the embodiment of the present invention.

[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, so that the light at the retinal object height of -10 mm to -10.1 mm (preferably the light at -10.08 mm) can 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 the non-field of view center 0 mm 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 of the field of view light at the upper and lower edges 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° field of view in the eye, the transmission lens group 5 in the embodiment of the present invention includes: 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 in sequence along the first optical path direction; 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 retina, thereby achieving large field of view aberration correction.

[0064] 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 retina of the human eye, thereby achieving aberration correction for different diopters of the human eye.

[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 designs of the sixth lens, the seventh lens and the eighth lens make the widths of the light rays in each field of view equal while correcting the aberrations, so that subsequent lenses can perform aberration and angle correction on the light rays in 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 direction is a convex surface, the radius of curvature is set to -130 to -140 mm, the second surface is a concave surface relative to the first surface, the radius of curvature is set to 20 to 25 mm, the third surface is a concave surface, 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 a convex surface, and the radius of curvature is set to -1310 to -1320 mm. The second surface is a convex surface, and the radius of curvature is set to -70 to -80 mm. 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 a convex surface, the radius of curvature is set to -250 to -260 mm, the second surface is a concave surface, the radius of curvature is set to 320 to 330 mm, and 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, the radius of curvature is set to -80 to -90 mm, the second surface is a convex surface, the radius of curvature is set to -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, the first surface along the first optical path direction is a concave surface, the curvature radius is set to 80-90 mm, the second surface is a concave surface, the curvature radius is set to 40-50 mm, and the center thickness between the two surfaces is 30-35 mm;

[0072] The first surface of the sixth lens along the first optical path is a convex surface, the radius of curvature is set to -60 to -70 mm, the second surface is a concave surface, the radius of curvature is set to 40 to 50 mm, and 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, the radius of curvature is set to -10 to -15 mm, the second surface is a convex surface, the radius of curvature is set to -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 direction is a concave surface, and the radius of curvature is set to 1500-1520 mm. The second surface is a concave surface, 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 embodiments 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 radius of curvature 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 gap between the lenses of the transmission lens group, the imaging effect is further improved. By moving the fifth lens (focusing lens) between the fourth lens and the sixth lens, the system can perform imaging compensation for human eyes with a diopter ranging from -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 2As shown, it is 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, the large field of view aberration correction and the human eye diopter aberration correction can be achieved. It can be seen from the figure that, unlike the conventional design method in which the light at the center of the field of view (at the retinal object plane height of 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 distance between the two foci of the ellipsoidal reflector 6, the light at the retinal object 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 of 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 within the diopter range of -15D to +15D. Figure 3 shown.

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

[0082] The designed ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system is used to perform full-field imaging with the light source 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, and then enter the transmission mirror group and the ellipsoidal reflector through the scanning module, and then reach the retina of the human eye through the pupil; the reflected light 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 488nm wavelength. Figure 5 This is the full field of view spot diagram at 520nm wavelength. Figure 6 This is the full field of view spot diagram at 635nm wavelength. 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 are obtained at each wavelength. Fields of view 1 to 10 correspond to object planes 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 of each field of view is shown in Table 1 below:

[0084] Table 1 RMS radius corresponding to field 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] It can be seen from Table 1 that 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 is needed, in conjunction with a transmission lens group, to achieve a clear imaging with a single extraocular field of view of 135° (intraocular field of view of 200°), and a full-field optical resolution of 15um. The entire system has 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 only 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 protection scope 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 light path direction, 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 light focusing module (3) and the light splitting module (2) in sequence along the second light path direction, and then is received by the detection module to form an image of the retina of the human eye; The center of the scanning module (4) and the center of the transmission lens 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 lens 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 lens group (5) form a conjugate relationship; the transmission lens group (5) comprises a movable focusing lens, which is used to change 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.

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 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.

3. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 1 or 2, characterized in that: The transmission lens group (5) comprises 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 lens, the seventh lens and the eighth lens are used to correct the aberration of the reflected light within the 200° field angle of the human eye retina; 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, so as to form a clear image of the retina of the human eye with different diopters; 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 compatible with the size of the scanning module (4).

4. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 3, characterized in that: The first lens is a cemented lens, the first surface along the first optical path is a convex surface with a curvature radius of -130 to -140 mm, the second surface is a concave surface with a curvature radius of 20 to 25 mm, the third surface is a concave surface 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; The first surface of the second lens along the first optical path is a convex surface with a curvature radius of -1310 to -1320 mm, the second surface is a convex surface 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, and 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 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; The first surface of the fifth lens 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; The first surface of the sixth lens along the first optical path is a convex surface with a curvature radius of -60 to -70 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 6 to 7 mm; 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; The first surface of the eighth lens along the first optical path is a concave surface with a curvature radius of 1500-1520 mm, the second surface is a concave surface with a curvature radius of 1530-1540 mm, and the center thickness between the two surfaces is 13-14 mm.

5. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 4, 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 as the focusing lens moves between the fourth lens and the sixth lens according to the diopter of the human eye; the gap between the sixth lens and the seventh lens is 1-2 mm; The gap between the seventh lens and the eighth lens is 4-5 mm.

6. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 5, characterized in that: The diameter of each lens from the first lens to the eighth lens is less than 70 mm.

7. 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).

8. The ultra-wide-angle ellipsoidal confocal laser scanning fundus imaging system according to claim 7, 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, so as to correct the chromatic aberration introduced by the multi-wavelengths.

9. 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.

10. 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 electrical signal to the host computer (9); the host computer (9) performs human eye retinal imaging based on the electrical signal.

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