An optical imaging system capable of switching imaging between an anterior segment and a posterior segment of an eye

Abstract

This invention proposes an optical imaging system capable of switching between anterior and posterior segment imaging. In the illumination system's optical path, light from the first light source is focused by a condenser lens and then sequentially passes through a rear lens group, an front lens group, an aperture stop, a central lens, and an eyepiece before illuminating the pupil. When imaging the anterior segment, the front lens group is moved into the imaging system. Light exiting the ocular surface first passes through the eyepiece and is then focused and expanded by the front lens group. It then sequentially passes through the aperture stop, a refraction lens, an aberration-correcting lens group, and a focusing lens group before being connected to a CCD for imaging. When imaging the posterior segment, the front lens group is moved out of the imaging system. Light from the fundus crosses through the pupil, passes through the eyepiece and is focused to the aperture stop. It then sequentially passes through the refraction lens, an aberration-correcting lens group, and a focusing lens group before being connected to a CCD for imaging. This invention achieves efficient switching between anterior and posterior segment imaging, high-definition imaging, and convenient clinical operation, significantly improving the accuracy and efficiency of ophthalmic diagnosis.

Description

Technical Field

[0001] This invention relates to the field of ophthalmic imaging equipment technology, and in particular to an optical imaging system capable of switching between anterior and posterior segment imaging. Background Technology

[0002] In the field of ophthalmology, imaging of the anterior segment (such as the cornea, iris, and lens) and the posterior segment (such as the retina and optic nerve) is a core component of disease diagnosis, surgical planning, and efficacy evaluation. Traditional ophthalmic imaging equipment typically employs a fixed optical path design, making it difficult to simultaneously meet the high-quality imaging requirements of both the anterior segment (cornea, iris, etc.) and the posterior segment (retina, choroid, etc.). Existing technologies sometimes achieve dual-mode imaging by mechanically switching between different optical modules, but this suffers from complex optical paths, time-consuming switching, and unstable image quality. For example, anterior segment imaging often uses a slit-lamp microscope structure, employing oblique illumination and microscopic magnification to observe structures such as the cornea and lens; while posterior segment imaging relies on a fundus camera or OCT (Optical Coherence Tomography) system, acquiring retinal images through transmitted illumination and long-focal-length objectives. This separate design results in bulky and expensive equipment, and requires frequent equipment switching or patient repositioning during clinical operations, impacting diagnostic and treatment efficiency. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention aims to provide an optical imaging system that can switch between anterior and posterior segment imaging. The imaging mode switching is achieved by a movable / removable anterior segment lens group, and precise focusing is achieved in conjunction with the axial movement of the focusing lens group.

[0004] To achieve the above objectives, this invention proposes an optical imaging system capable of switching between anterior and posterior segment imaging, comprising an illumination system and an imaging system. The illumination system includes a first light source, a condenser lens, a rear mirror group, a front mirror group, and an aperture stop arranged sequentially. The imaging system includes an eyepiece, a movable anterior segment mirror group, a refractor, an aberration-correcting mirror group, and a focusing mirror group arranged sequentially. The focusing mirror group can move back and forth along the optical axis. The illumination system is connected to the imaging system through a central lens, which is positioned between the anterior segment mirror group and the refractor of the imaging system and connected in front of the aperture stop of the illumination system.

[0005] In the optical path of the lighting system, the light from the first light source is focused by the condenser lens and then passes through the rear mirror group, the front mirror group, the aperture stop, the central lens, and the eyepiece in sequence to illuminate the pupil.

[0006] When imaging the anterior segment of the eye, the anterior segment lens group is moved into the imaging system. Light exiting from the ocular surface first passes through the eyepiece and converges, then is expanded and converged by the anterior segment lens group, and then passes sequentially through the aperture stop, refractor, aberration-correcting lens group, and focusing lens group before being connected to the CCD for imaging. When imaging the posterior segment of the eye, the anterior segment lens group is moved out of the imaging system. Light from the fundus crosses through the pupil, passes through the eyepiece and converges to the aperture stop, and then passes sequentially through the refractor, aberration-correcting lens group, and focusing lens group before being connected to the CCD for imaging.

[0007] The front segment lens assembly is movably mounted in the imaging system via a linear guide or a rotary guide. The travel of the linear guide or rotary guide covers the designed working position and clearance position of the front segment lens assembly. A positioning stop is provided at the designed working position. When the front segment lens assembly slides along the linear guide or rotary guide to abut against the positioning stop, the front segment lens assembly moves into the imaging system. When the front segment lens assembly slides along the linear guide or rotary guide away from the designed working position, the front segment lens assembly moves out of the imaging system.

[0008] The above solution also includes a focusing module, which comprises a second light source, an aspherical lens group, and a focusing lens group. The focusing module is connected to the central lens through the focusing lens group. The focusing lens group can move back and forth along the optical axis to adjust the optical path parameters and ensure clear imaging.

[0009] In the above scheme: black dots are arranged between the rear lens group and the front lens group to block stray light.

[0010] In the above scheme, the rear lens group, front lens group, aberration correction lens group, and focusing lens group are all composed of multiple lenses.

[0011] In the above scheme: the aberration correction lens group consists of a first positive lens, a second negative lens, a third positive lens, a fourth negative lens, and a first cemented lens, arranged from closest to furthest from the pupil.

[0012] In the above scheme: the anterior segment lens group consists of a fifth negative lens and a sixth positive lens, arranged sequentially from the closest to the pupil to the furthest from the pupil.

[0013] In the above scheme: the focusing lens group consists of a seventh positive lens, a second cemented lens, a third cemented lens, and an eighth positive lens, arranged from closest to furthest from the pupil.

[0014] In the above scheme: a variable aperture is provided between the second cemented lens and the third cemented lens. The variable aperture is used to adjust the amount of light transmitted and the numerical aperture, control the illuminance, beam angle and depth of field, suppress stray light and higher-order aberrations, and improve the uniformity of illumination and imaging quality.

[0015] In the above scheme, the refracting mirror is arranged at a 45° angle along the optical axis.

[0016] In the above scheme, the eyepiece is an aspherical lens, which effectively reduces spherical aberration and improves the initial imaging quality.

[0017] The beneficial effects of this invention are:

[0018] 1. During anterior segment imaging, the anterior segment lens group is inserted into the optical path to supplement the short focal length imaging path, adapting to high-resolution acquisition of ocular surface structures. During posterior segment imaging, the anterior segment lens group is removed, and the optical path passes directly through components such as the refractor and aberration-correcting lens group, adapting to the long-path imaging requirements of the fundus. This switching eliminates the need for complex adjustments, improving clinical operational efficiency. 2. As the connecting hub between the illumination and imaging systems, the intermediate lens is positioned between the aperture stop and the eyepiece, ensuring spatial overlap between the illumination beam and the imaging optical path, avoiding light loss or stray light interference, and improving the signal-to-noise ratio. 3. The movement of the focusing lens group can be combined with electric control or an autofocus algorithm to automatically adjust the focal length based on the patient's axial length data or real-time image feedback, reducing human error and improving the standardization of the examination.

[0019] In summary, this invention achieves efficient switching between anterior and posterior segment imaging, high-definition imaging, and convenient clinical operation through innovations such as optical path reconstruction, aberration correction and focusing coordination, and compact optical path design. It significantly improves the accuracy and efficiency of ophthalmic diagnosis and has broad clinical application value. Attached Figure Description

[0020] Figure 1 This is the optical path diagram of the lighting system.

[0021] Figure 2 This is the optical path diagram of the posterior segment imaging system.

[0022] Figure 3 This is the optical path diagram of the anterior segment imaging system.

[0023] Figure 4 This is a schematic diagram of the structure of the present invention.

[0024] Figure 5 This is the MTF transfer function plot for anterior segment imaging.

[0025] Figure 6 This is a graph of the MTF transfer function for imaging the posterior segment of the eye. Detailed Implementation

[0026] like Figure 1 As shown in Figure 6, an optical imaging system capable of switching between anterior and posterior segment imaging mainly consists of an illumination system, an imaging system, and a focusing module.

[0027] The illumination system includes a first light source 1, a condenser lens 2, a rear mirror group 3, a front mirror group 4, and an aperture stop 5 arranged in sequence. The imaging system includes an eyepiece 6, a front segment mirror group 7 that can be moved out or in, a refracting mirror 8, an aberration-correcting mirror group 9, and a focusing mirror group 10 arranged in sequence. The focusing mirror group 10 can move back and forth along the optical axis.

[0028] Specifically, a black dot 17 (located at the intersection of light rays) is arranged between the rear lens group 3 and the front lens group 4 to block stray light.

[0029] The refracting mirror 8 is arranged at a 45° angle along the optical axis.

[0030] The eyepiece 6 is an aspherical lens, which effectively reduces spherical aberration and improves the initial image quality.

[0031] The illumination system is connected to the imaging system through a central lens 12. The central lens 12 is positioned between the front lens group 7 and the refractor 8 of the imaging system and is connected in front of the aperture stop 5 of the illumination system.

[0032] The focusing module includes a second light source 13, an aspherical lens group 14, and a focusing lens group 15. The focusing module is connected to the central lens 12 through the focusing lens group 15. The focusing lens group 15 can move back and forth along the optical axis (a guide rail is arranged along the optical axis, and the focusing lens group 15 moves on the guide rail) to adjust the optical path parameters and ensure clear imaging.

[0033] In the optical path of the lighting system, the light from the first light source is focused by the condenser lens 2 and then sequentially passes through the rear mirror group 3, the front mirror group 4, the aperture stop 5, the central lens 12, and the eyepiece 6 before illuminating the pupil.

[0034] When imaging the anterior segment, the anterior segment lens group 7 is moved into the imaging system. The light comes out from the ocular surface (label 11 refers to the human eye model), first passes through the eyepiece 6 to converge, then passes through the anterior segment lens group 7 to expand and converge, and then passes through the aperture stop, refractor 8, aberration aberration lens group 9, and focusing lens group 10 in sequence before being connected to the CCD for imaging.

[0035] When imaging the posterior segment of the eye, the anterior segment lens group 7 is removed from the imaging system. The light from the fundus crosses through the pupil, converges to the aperture stop through the eyepiece 6, and then passes through the refracting mirror 8, the aberration-correcting lens group 9, and the focusing lens group 10 in sequence before being connected to the CCD for imaging.

[0036] The position of the fundus is conjugate to the position of the focusing surface of the aberration-correcting lens group, and the intersection of the optical paths within the focusing lens group is conjugate to the position of the pupil.

[0037] The front segment lens group 7 is movably mounted in the imaging system via a linear guide or a rotary guide. The travel of the linear guide or rotary guide covers the designed working position and clearance position of the front segment lens group 7. A positioning stop is provided at the designed working position. When the front segment lens group 7 slides along the linear guide or rotary guide to abut against the positioning stop, the front segment lens group 7 moves into the imaging system. When the front segment lens group 7 slides along the linear guide or rotary guide to move away from the designed working position, the front segment lens group 7 moves out of the imaging system.

[0038] The rear lens group 3, the front lens group 4, the aberration correction lens group 9, and the focusing lens group 10 are all composed of multiple lenses.

[0039] Specifically, the aberration correction lens group 9 consists of, from closest to the pupil to furthest from the pupil, a first positive lens, a second negative lens, a third positive lens, a fourth negative lens, and a first cemented lens.

[0040] Specifically, the focusing lens group 10 consists of the seventh positive lens, the second cemented lens, the third cemented lens, and the eighth positive lens, arranged from closest to furthest from the pupil.

[0041] A variable aperture 16 is provided between the second and third cemented lenses. The variable aperture 16 is used to adjust the amount of light transmitted and the numerical aperture, control the illuminance, beam angle and depth of field, suppress stray light and higher-order aberrations, and improve illumination uniformity and image quality.

[0042] Specifically, the anterior lens group 7 consists of the fifth negative lens and the sixth positive lens, arranged from closest to the pupil to furthest from the pupil. The negative lens is used for dilation, and the positive lens is used for convergence.

[0043] Specifically, the rear lens group 3 consists of a third cemented lens and a ninth lens, arranged sequentially from the closest to the first light source 1 to the furthest from the first light source 1.

[0044] Specifically, the front lens group 4 consists of the tenth lens and the fourth cemented lens, arranged sequentially from the closest to the first light source 1 to the furthest from the first light source 1.

[0045] Figure 5 In the diagram, A represents the diffraction limit, B represents the center of the field of view, C represents the half-field sagitta, D represents the edge field of view sagitta, E represents the edge field of view meridion, and F represents the half-field of view meridion. All the imaging curves approach the diffraction limit, proving that the imaging quality of this optical system is good. Figure 6 In the diagram, T represents the diffraction limit, K represents the center of the field of view, G represents the 10% field of view meridion, H represents the 10% field of view sagitta, I represents the 23% field of view meridion, J represents the 23% field of view sagitta, M represents the 38% field of view meridion, L represents the 38% field of view sagitta, N represents the 50% field of view meridion, O represents the 50% field of view sagitta, P represents the 75% field of view meridion, S represents the 75% field of view sagitta, R represents the 100% field of view meridion, and Q represents the 100% field of view sagitta. All the imaging curves are close to the diffraction limit, proving that the imaging quality of this optical system is good.

Claims

1. An optical imaging system capable of switching between anterior and posterior segment imaging, comprising an illumination system and an imaging system, characterized in that: The illumination system includes a first light source (1), a condenser lens (2), a rear mirror group (3), a front mirror group (4), and an aperture stop (5) arranged in sequence. The imaging system includes an eyepiece (6), a front segment mirror group (7) that can be moved out or in, a refractor (8), an aberration-correcting mirror group (9), and a focusing mirror group (10) arranged in sequence. The focusing mirror group (10) can move back and forth along the optical axis. The illumination system is connected to the imaging system through a central lens (12). The central lens (12) is arranged between the front segment mirror group (7) and the refractor (8) of the imaging system and is connected in front of the aperture stop (5) of the illumination system. In the lighting system's optical path, the light from the first light source is focused by the condenser lens (2) and then sequentially passes through the rear lens group (3), the front lens group (4), the aperture stop (5), the central lens (12), and the eyepiece (6) to illuminate the pupil. When imaging the anterior segment of the eye, the front lens group (7) is moved into the imaging system. The light comes out from the surface of the eye, first passes through the eyepiece (6) to converge, and then passes through the front lens group (7) to expand and converge. Then, it sequentially passes through the aperture stop, the refractor (8), the aberration-correcting lens group (9), and the focusing lens group (10) before being connected to the CCD for imaging. When imaging the posterior segment of the eye, the front lens group (7) is moved out of the imaging system. The light from the fundus crosses through the pupil, passes through the eyepiece (6) to converge to the aperture stop, and then sequentially passes through the refractor (8), the aberration-correcting lens group (9), and the focusing lens group (10) before being connected to the CCD for imaging. The anterior segment lens assembly (7) is movably mounted in the imaging system via a linear guide or a rotary guide. The travel of the linear guide or rotary guide covers the designed working position and the clearance position of the anterior segment lens assembly (7). A positioning stop is provided at the designed working position. When the anterior segment lens assembly (7) slides along the linear guide or rotary guide to abut against the positioning stop, the anterior segment lens assembly (7) moves into the imaging system. When the anterior segment lens assembly (7) slides along the linear guide or rotary guide away from the designed working position to the clearance position, the anterior segment lens assembly (7) moves out of the imaging system. It also includes a focusing module, which includes a second light source (13), an aspherical lens group (14), and a focusing lens group (15). The focusing module is connected to the central lens (12) through the focusing lens group (15). The focusing lens group (15) can move back and forth along the optical axis. A black dot (17) for blocking stray light is arranged between the rear lens group (3) and the front lens group (4). The rear lens group (3), the front lens group (4), the aberration aberration lens group (9), and the focusing lens group (10) are all composed of multiple lenses. The aberration aberration lens group (9) consists of a first positive lens, a second negative lens, a third positive lens, a fourth negative lens, and a first cemented lens, from near the pupil to far away from the pupil. The front lens group (7) consists of a fifth negative lens and a sixth positive lens, from near the pupil to far away from the pupil. The focusing lens group (10) consists of a seventh positive lens, a second cemented lens, a third cemented lens, and an eighth positive lens, from near the pupil to far away from the pupil. 2.The optical imaging system capable of switching between anterior segment and posterior segment imaging according to claim 1, wherein: A variable aperture (16) is provided between the second and third cemented mirrors.

3. The optical imaging system capable of switching between anterior and posterior segment imaging according to claim 1, characterized in that: The refracting mirror (8) is arranged at a 45° angle along the optical axis.

4. The optical imaging system capable of switching between anterior and posterior segment imaging according to claim 1, characterized in that: The eyepiece (6) is an aspherical lens.

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