Living cornea confocal tomography microscope imaging system

Abstract

The invention discloses a living cornea confocal tomography microscope imaging system, and belongs to the technical field of ophthalmology imaging. The objective lens sequentially comprises a first lens group, a diaphragm, a second lens group and a third lens group from an image space to an object space, wherein the surface of the objective lens is covered with a cornea cap; and the lens groups meet the designed proportional relation. The microscope objective provided by the invention can perform high-resolution imaging on corneal cells in different layers, the imaging quality is close to the diffraction limit, experimental results prove that the microscope objective is matched with a corneal cap, high-resolution images of cells in different layers within the range of 0-572 microns can be clearly obtained, the object space field of view is large, and the imaging quality is close to the diffraction limit. Therefore, the shooting area can be adjusted without repeatedly moving the inspection equipment in the inspection process; compared with the prior art, a doctor can obtain more operation space, the operation difficulty of cornea imaging is remarkably reduced, and the diagnosis efficiency is further improved.

Description

Technical Field

[0001] The invention relates to a living cornea confocal tomography microscope imaging system, belonging to the technical field of ophthalmological imaging. Background Art

[0002] In vivo confocal microscopy is mainly used for auxiliary examination of ophthalmic diseases such as cornea and conjunctiva. It can observe the formed elements in the cornea in a multi-level and three-dimensional manner without the need for traditional tissue sectioning, fixation and staining. It is an important tool for the diagnosis of corneal diseases, is non-traumatic to the cornea, can be performed repeatedly, and is more sensitive and specific than corneal scraping microscopy and corneal scraping culture.

[0003] The existing corneal cell imaging device is a modified and upgraded version of the mature fundus imaging reflective confocal microscopy system. A conventional microscope objective lens is added in front of the original objective lens, so that the parallel light originally incident on the pupil in different directions is converged into the focal plane of the focus scanning microscope objective lens. When the human cornea is placed on the focal plane, the focus of the system scan will return signals of different intensities according to the corneal cell structure, and finally obtain the corneal cell structure image.

[0004] The current products on the market use a 63x numerical aperture NA0.95 water immersion microscope objective lens produced by a third-party company, Zeiss, as the objective lens. It was originally designed for high-resolution microscopes and is mainly used for microscopic imaging of samples fixed with a cover glass. The cover glass thickness of the objective lens is 0.2mm, its working distance is 2mm, and the imaging field of view supports 350 microns. In actual corneal imaging, the current products on the market use a plastic corneal cap as the cover glass, which is placed between the objective lens and the human cornea.

[0005] The conventional microscope objective lenses used in current products have the following three shortcomings: 1. High-resolution microscope objective lenses converge incident collimated light into high numerical aperture converged light. The focus quality of the converged light is very sensitive to the thickness of the cover glass. The thickness and material of the plastic corneal cap actually used are different from the cover glass designed by the objective lens. Therefore, certain aberrations will be introduced into the high-resolution image, resulting in a decrease in image quality; 2. In order to obtain high-resolution images, the system uses high-magnification and high-numerical aperture objective lenses, but the object field of view corresponding to the high magnification is correspondingly reduced, and the image range captured by a single imaging is It is only 350 microns, while in clinical examinations, doctors need to examine the human cornea area at the millimeter scale, so they need to move the equipment repeatedly to take pictures, which greatly limits the promotion of clinical applications; 3. The general use environment of high-resolution microscope objectives enables imaging of cover glass samples, while in human cornea applications, some clinical examination doctors will use equipment to examine eyelids and other parts. The shorter working distance requires doctors to manually open the eyelids of the person to be tested and apply a sticky tape to the eyelids for inspection. The too close working distance greatly increases the difficulty of the actual operability of eyelid inspection. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a living corneal confocal tomography microscope imaging system, and the technical solution is as follows:

[0007] The first object of the present invention is to provide a microscope objective lens for in vivo corneal confocal tomography, which comprises, from the image side to the object side, a first lens group G1, a stop 3, a second lens group G2 and a third lens group G3, and the surface of the objective lens is covered with a corneal cap 9;

[0008] The first lens group G1 is used to diverge the incident parallel light, the aperture 3 is used to limit the spot diameter after divergence, the second lens group G2 includes a double-cemented lens for controlling the chromatic aberration in the narrow-band spectrum of the light source, and the third lens group G3 is used to converge the light to the object focal plane 10;

[0009] The focal length of each lens group in the objective lens satisfies the following conditions:

[0010] 0.19≤|F G1 / F G2 |≤0.39

[0011] 1.5≤|F G1 / F G3 |≤3

[0012] Among them, F G1 、F G2 、F G3 They respectively represent the combined focal lengths of the first lens group G1, the second lens group G2, and the third lens group G3.

[0013] Optionally, the distance between the objective lens and the corneal cap ranges from 0.8 to 2.7 mm, and the thickness of the corneal cap ranges from 0.4 to 0.8 mm.

[0014] Optionally, the refractive index range of the corneal cap is: 1.2-2.

[0015] Optionally, the first lens group G1 includes: a plano-concave lens 1 and a meniscus lens 2 .

[0016] Optionally, the second lens group G2 includes: a double-cemented lens consisting of a biconvex lens 4 and a meniscus lens 5 .

[0017] Optionally, the third lens group G3 includes: a meniscus lens 6 , a meniscus lens 7 and a plano-convex lens 8 .

[0018] Optionally, the operating wavelength of the objective lens is 670 nm.

[0019] The second object of the present invention is to provide a living cornea confocal tomography microscope imaging system, comprising: a detector, a light source, an optical path, a microscope objective lens as described in any one of the above items, and a corneal cap;

[0020] During the imaging process, the light emitted by the light source enters the microscope objective lens through the optical path, is focused on the cornea through the microscope objective lens and the corneal cap, and returns signals of different intensities according to the corneal cell structure, which are finally collected by the detector.

[0021] Optionally, the light source is a laser diode.

[0022] Optionally, ophthalmic gel is used between the microscope objective and the corneal cap.

[0023] The beneficial effects of the present invention are:

[0024] The present invention proposes a microscope objective lens for in vivo corneal confocal tomography, designs the internal lens structure and lens parameters, and uses the microscope objective lens proposed by the present invention to perform high-resolution imaging of corneal cells in different layers, and the imaging quality is close to the diffraction limit and the imaging quality is high. Experimental results show that in combination with a corneal cap, the present invention can clearly obtain high-resolution images of cells in different layers within the range of 0-572μm, which is beneficial to the identification and diagnosis of lesions and improves the diagnostic efficiency.

[0025] The microscope objective lens for in vivo corneal confocal tomography of the present invention has an object field diameter greater than 850 microns, which can cover the inspection range of the human cornea. Therefore, during the inspection process, there is no need to repeatedly move the inspection equipment to adjust the shooting area, thereby reducing the operating difficulty of the doctor at the millimeter scale. The working distance is greater than 2.5 mm. Compared with the existing technology, the doctor can obtain more operating space, reducing the difficulty of inspecting the eyes and further improving the diagnostic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a structural diagram of the in vivo cornea confocal tomography microscope imaging system of the present invention.

[0028] Figure 2 1 is a diagram showing the optical path structure of a microscope objective lens according to an embodiment of the present invention.

[0029] Figure 3This is a diagram of the imaging effect of the microscope objective lens provided by an embodiment of the present invention.

[0030] Figure 4 1 is a vertical axis aberration diagram of the object focal plane according to an embodiment of the present invention.

[0031] Figure 5 1 is an axial aberration diagram of the object focal plane according to an embodiment of the present invention.

[0032] Figure 6 This is a measured picture of the corneal stroma layer of an embodiment of the present invention.

[0033] Figure 7 Schematic diagram of the operating distance when imaging corneal cells in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Embodiment 1:

[0036] This embodiment provides a microscope objective lens for in vivo corneal confocal tomography, see Figure 2 , from the image side to the object side, it includes: a first lens group G1, an aperture 3, a second lens group G2 and a third lens group G3, and the objective lens is covered with a corneal cap 9;

[0037] The first lens group G1 is used to diverge the incident parallel light, the aperture 3 is used to limit the spot diameter after divergence, the second lens group G2 includes a double cemented lens for controlling the chromatic aberration in the narrow-band spectrum of the light source, and the third lens group G3 is used to converge the light to the object focal plane 10;

[0038] The focal length of each lens group in the objective lens meets the following conditions:

[0039] 0.19≤|F G1 / F G2 |≤0.39

[0040] 1.5≤|F G1 / F G3 |≤3

[0041] Among them, F G1 、F G2 、F G3 They respectively represent the combined focal lengths of the first lens group G1, the second lens group G2, and the third lens group G3.

[0042] Embodiment 2:

[0043] This embodiment provides a microscope objective lens for in vivo corneal confocal tomography, see Figure 2, from the image side to the object side, it includes: a first lens group G1, an aperture 3, a second lens group G2 and a third lens group G3, and the objective lens is covered with a corneal cap 9;

[0044] The first lens group G1 is used to diverge incident parallel light. In this embodiment, the first lens group G1 includes a plano-concave lens 1 and a meniscus lens 2 .

[0045] Aperture 3 is used to limit the spot diameter after divergence.

[0046] The second lens group G2 is a double-cemented lens composed of a biconvex lens 4 and a meniscus lens 5, and is used to control the chromatic aberration in the narrow-band spectrum of the light source.

[0047] The third lens group G3 is used to converge the light to the object focal plane 10 . In this embodiment, the third lens group G3 is composed of a meniscus lens 6 , a meniscus lens 7 and a plano-convex lens 8 .

[0048] In order to achieve high-resolution imaging of different layers of corneal cells, the combined focal length of the first lens group G1, the second lens group G2, and the third lens group G3 needs to meet the following conditions:

[0049] 0.19≤|F G1 / F G2 |≤0.39

[0050] 1.5≤|F G1 / F G3 |≤3

[0051] Among them, F G1 、F G2 、F G3 They respectively represent the combined focal lengths of the first lens group G1, the second lens group G2, and the third lens group G3.

[0052] After the above focal length ratio is met, the distance between the lenses can be adjusted using a knob during the inspection process to adjust the focal plane of the objective lens, thereby achieving imaging of cells in different layers of the cornea.

[0053] The parameters and specifications of the objective lens in this embodiment are as follows:

[0054] Table 1: Objective system parameters

[0055] Objective lens parameters Design indicators Focal length(mm) 2.82 Numerical aperture 0.8 Object field of view (μm) 850 Working distance (mm) 2.5 Working wavelength(nm) 670±5

[0056] The lenses in the objective lens of this embodiment can adopt the following specifications:

[0057] Table 2: Parameters of the optical components in the objective

[0058]

[0059]

[0060] Figure 4-5 It is the error analysis icon of the objective lens, where the blue solid line represents the analysis result at 670nm, the green dotted line represents the analysis result at 675nm, and the red long and short dashed lines represent the analysis result at 665nm.

[0061] Figure 4 This is the error diagram of the vertical axis of the objective lens. The horizontal axis in each chart represents the normalized pupil coordinates, and the two ends of the coordinates are coded as normalized pupil -1 to +1; the vertical axis represents the error value, and the vertical axis scale extreme value is ±5μm. Among them, the first line is the analysis result of the on-axis field of view, the second line is the analysis result of the half field of view, and the third line is the analysis result of the edge field of view. Among them, the left column is the error analysis result in the Y direction, and the right column is the error analysis result in the X direction.

[0062] Figure 5 It is the axial error diagram of the objective lens. The abscissa is the axial error value in mm, and the ordinate is the normalized objective lens pupil.

[0063] Figure 6 This is the actual imaging result of the corneal stroma measured by the objective lens, and the scale is 100μm.

[0064] according to Figure 4-5 The objective lens has a vertical axis error RMS value of less than 0.5 μm in the on-axis field of view under the corresponding numerical aperture and field of view, a vertical axis error RMS value of less than 0.5 μm in the half field of view, and a vertical axis error RMS value of less than 1 μm in the edge field of view; and an axial error PV value of less than 3 μm. The above analysis results and Figure 6 The measured images of corneal stroma show that the objective lens has high resolution imaging quality to resolve the subtle cell structure of the cornea.

[0065] When imaging corneal cells, eye gel needs to be dropped on the surface of the objective lens, and then a corneal cap is covered on the surface of the objective lens. During the inspection, the corneal cap is in contact with the cornea.

[0066] like Figure 7 As shown, in this embodiment, the thickness of the corneal cap is 0.4-0.8 mm, the distance from the objective lens surface to the corneal cap (i.e., the thickness of the eye gel) is 0.8-2.7 mm, and the distance from the corneal cap surface to the focal plane is 0-15 mm. Therefore, the working distance for the doctor to examine is 2.8-3.4 mm, which is significantly improved compared to the existing 2 mm.

[0067] 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, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A microscope objective lens for in vivo corneal confocal tomography, characterized in that: The objective lens comprises, from the image side to the object side, a first lens group (G1), a diaphragm (3), a second lens group (G2) and a third lens group (G3); the surface of the objective lens is covered with a corneal cap (9); The first lens group (G1) is used to diverge incident parallel light, the aperture (3) is used to limit the diameter of the diverged light spot, the second lens group (G2) comprises a double-cemented lens for controlling chromatic aberration in the narrow-band spectrum of the light source, and the third lens group (G3) is used to converge the light to the object focal plane (10); The focal length of each lens group in the objective lens satisfies the following conditions: 0.19≤|F G1 / F G2 |≤0.39 1.5≤|F G1 / F G3 |≤3 Among them, F G1 、F G2 、F G3 Respectively represent the combined focal lengths of the first lens group (G1), the second lens group (G2), and the third lens group (G3).

2. The microscope objective lens for in vivo corneal confocal tomography according to claim 1, characterized in that: The distance between the objective lens surface and the corneal cap is in the range of 0.8-2.7 mm, and the thickness of the corneal cap is in the range of 0.4-0.8 mm.

3. The microscope objective lens for in vivo corneal confocal tomography according to claim 1, characterized in that: The refractive index range of the corneal cap is: 1.2-2.

4. The microscope objective lens for in vivo corneal confocal tomography according to claim 2, characterized in that: The first lens group (G1) comprises a plano-concave lens (1) and a meniscus lens (2).

5. The microscope objective lens for in vivo corneal confocal tomography according to claim 2, characterized in that: The second lens group (G2) comprises a double-cemented lens consisting of a double convex lens (4) and a meniscus lens (5).

6. The microscope objective lens for in vivo corneal confocal tomography according to claim 2, characterized in that: The third lens group (G3) comprises a meniscus lens (6), a meniscus lens (7) and a plano-convex lens (8).

7. The microscope objective lens for in vivo corneal confocal tomography according to claim 2, characterized in that: The working wavelength of the objective lens is 670 nm.

8. A living corneal confocal tomography microscope imaging system, characterized in that: include: A detector, a light source, an optical path, a microscope objective lens and a corneal cap as claimed in any one of claims 1 to 6; During the imaging process, the light emitted by the light source enters the microscope objective lens through the optical path, is focused on the cornea through the microscope objective lens and the corneal cap, and returns signals of different intensities according to the corneal cell structure, which are finally collected by the detector.

9. The in vivo corneal confocal tomography microscope imaging system according to claim 8, characterized in that: The light source is a laser diode.

10. The in vivo corneal confocal tomography microscope imaging system according to claim 8, characterized in that: Ophthalmic gel was used between the microscope objective and the corneal cap.

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