In-vivo corneal confocal tomography microscope imaging system

Abstract

The application discloses a kind of living cornea confocal tomography microscope imaging systems, belong to ophthalmic imaging technical field.The objective of the present application includes successively: first mirror group, diaphragm, second mirror group and third mirror group from image side to object side, objective surface covers corneal cap;Mirror group meets the proportion relationship of design between each other.The micro objective lens proposed in the present application can perform high-resolution imaging on corneal cells of different layers, and the imaging quality is close to the diffraction limit, and the experimental results prove that, cooperating with corneal cap, the present application can clearly obtain high-resolution images of cells in different layers within the range of 0-572 μm, and the object field is large, so it is not necessary to repeatedly move the inspection equipment to adjust the shooting area during the inspection process;Working distance is long, compared with prior art, doctors can obtain more operating space, significantly reduce the operation difficulty of corneal imaging, and further improve the diagnosis efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of in vivo corneal confocal tomography microscope imaging system, belong to ophthalmic imaging technical field. BACKGROUND

[0002] In vivo confocal microscopy is mainly used for auxiliary examination of diseases such as cornea and conjunctiva in ophthalmology, and can observe the formed elements in the cornea in multiple levels without traditional tissue sectioning, fixation and staining. It is an important tool for the diagnosis of corneal diseases, and it is non-invasive to the cornea and can be repeated. Compared with corneal scraping microscopy and corneal scraping culture, it has higher sensitivity and specificity.

[0003] The existing corneal cell imaging device is based on a mature fundus imaging reflection confocal microscopic imaging system, which adds a conventional microscopic objective lens in front of the original objective lens. The parallel light originally incident on the pupil in different directions is focused into a focal plane of the scanning microscopic objective lens. When the human cornea is placed on the focal plane, the focal point of the system will return different intensity signals according to the corneal cell structure, and finally obtain the corneal cell structure image.

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

[0005] The current product using a conventional microscopic objective lens has the following three shortcomings: 1. The high-resolution microscopic objective lens converges the incident collimated light into a high-numerical-aperture convergent light. The focal point quality of the convergent light is very sensitive to the thickness of the cover glass. The thickness and material of the actual plastic corneal cap used are different from those of the cover glass designed by the objective lens, so it will introduce certain aberration to the high-resolution image, causing the image quality to decrease; 2. In order to obtain a high-resolution image, the system uses a high-magnification high-numerical-aperture objective lens. However, the object field range corresponding to high magnification is correspondingly reduced, and the image range captured by single imaging is only 350 microns. In clinical examination, doctors need to examine the human cornea area in millimeter scale, so the equipment needs to be moved repeatedly for shooting, which greatly limits the promotion of clinical application; 3. The general use environment of the high-resolution microscopic objective lens is to image the cover glass sample, and in the application of human cornea, some clinical examination doctors will use the equipment to examine the eyelid and other parts. The short working distance requires the doctor to manually lift the eyelid of the person to be tested and apply it to the eyelid for examination. The short working distance increases the difficulty of the actual operability of the eyelid examination. SUMMARY

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

[0007] The first object of the present application is to provide a microscope objective for living corneal confocal tomography, which comprises, in order from the image side to the object side: a first lens group G1, an aperture stop 3, a second lens group G2, and a third lens group G3, and the surface of the objective covers a corneal cap 9;

[0008] The first lens group G1 is used to diverge the incident parallel light, the aperture stop 3 is used to limit the diameter of the light spot after divergence, the second lens group G2 comprises a doublet lens for controlling chromatic aberration in the narrowband 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 lengths of the lens groups in the objective satisfy the following conditions:

[0010] 0.19≤|F G1 / F G2 |≤0.39

[0011] 1.5≤|F G1 / F G3 |≤3

[0012] Wherein, 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.

[0013] Optionally, the distance between the objective and the corneal cap is in the range of 0.8-2.7mm, and the thickness of the corneal cap is in the range of 0.4-0.8mm.

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

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

[0016] Optionally, the second lens group G2 comprises a doublet lens composed of a double convex lens 4 and a meniscus lens 5.

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

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

[0019] The second object of the present application is to provide a living corneal confocal tomography microscope imaging system, comprising: a detector, a light source, an optical path, a microscope objective as claimed in any one of the preceding claims, and a corneal cap.

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

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

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

[0023] The present application has the following advantages:

[0024] The present application provides a microscope objective for living corneal confocal tomography, the internal lens structure and lens parameters are designed, and the microscope objective provided by the present application can be used for high-resolution imaging of corneal cells at different layers, and the imaging quality is close to the diffraction limit, the imaging quality is high, and the experimental results prove that, in cooperation with the corneal cap, the present application can clearly obtain high-resolution images of cells at different layers in the range of 0-572 mu m, which is conducive to the identification and diagnosis of lesions and improves the diagnosis efficiency.

[0025] The microscope objective for living corneal confocal tomography of the present application has a field of view diameter greater than 850 microns on the object side, which can cover the inspection range of the human cornea, so that the inspection equipment does not need to be repeatedly moved to adjust the shooting area during inspection, thereby reducing the operation difficulty of the doctor on the millimeter scale, and the working distance is greater than 2.5 mm, compared with the prior art, the doctor can obtain more operation space, and the operation difficulty of inspecting the eye is reduced, and the diagnosis efficiency is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 is a structural diagram of the living corneal confocal tomography microscope imaging system of the present application.

[0028] Figure 2 is a microscope objective optical path structure diagram of the embodiment of the present application.

[0029] Figure 3is an imaging effect diagram of the microscope objective provided by the embodiment of the present application.

[0030] Figure 4 is an axial aberration diagram of the object focal plane of the embodiment of the present application.

[0031] Figure 5 is an axial aberration diagram of the object focal plane of the embodiment of the present application.

[0032] Figure 6 is a measured diagram of the corneal stroma of the embodiment of the present application.

[0033] Figure 7 is a schematic diagram of the operation distance when the corneal cells are imaged in the embodiment of the present application. DETAILED DESCRIPTION

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

[0035] Embodiment 1:

[0036] The embodiment provides a microscope objective for in-vivo corneal confocal tomography, referring to Figure 2 from the image side to the object side in sequence: a first lens group G1, an aperture stop 3, a second lens group G2 and a third lens group G3, and a corneal cap 9 is covered on the objective;

[0037] The first lens group G1 is used for diverging the incident parallel light, the aperture stop 3 is used for limiting the diameter of the diverged light spot, the second lens group G2 comprises a doublet lens for controlling chromatic aberration in the narrowband spectrum of the light source, and the third lens group G3 is used for converging the light to the object focal plane 10;

[0038] The focal lengths of the lens groups in the objective meet the following conditions:

[0039] 0.19≤|F G1 / F G2 |≤0.39

[0040] 1.5≤|F G1 / F G3 |≤3

[0041] Wherein, 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.

[0042] Embodiment 2:

[0043] The embodiment provides a microscope objective for in-vivo corneal confocal tomography, referring to Figure 2The image side to the object side successively includes: the first mirror group G1, the diaphragm 3, the second mirror group G2 and the third mirror group G3, and the objective lens is covered by the corneal cap 9;

[0044] The first mirror group G1 is used for diverging the incident parallel light, and in the embodiment, the first mirror group G1 includes: a plano-concave lens 1 and a meniscus lens 2.

[0045] The diaphragm 3 is used for limiting the diameter of the diverged light spot.

[0046] The second mirror group G2 is composed of a double convex lens 4 and a meniscus lens 5 to form a doublet, and is used for controlling chromatic aberration in the narrow band spectrum of the light source.

[0047] The third mirror group G3 is used for converging the light to the object side focal plane 10, and in the embodiment, the third mirror group G3 is composed of a meniscus lens 6, a meniscus lens 7 and a plano-convex lens 8.

[0048] In order to meet the high-resolution imaging of different layers of corneal cells, the combined focal length of the first mirror group G1, the second mirror group G2 and the third mirror 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] Wherein, F G1 , F G2 , F G3 respectively represent the combined focal length of the first mirror group G1, the second mirror group G2 and the third mirror group G3.

[0052] After meeting the above focal length ratio relationship, the distance between the lenses is adjusted by the knob during the examination process, the focal plane of the objective lens can be adjusted, so as to realize the imaging of different layers of corneal cells.

[0053] The parameter specifications of the objective lens in the embodiment are as follows:

[0054] Table 1: Objective lens system parameters

[0055] Objective parameters Design criteria Focal length (mm) 2.82 Numerical aperture 0.8 Object field (pm) 850 Working distance (mm) 2.5 Working wavelength (nm) 670±5

[0056] The specifications of the lenses in the objective lens in the embodiment can be as follows:

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

[0058]

[0059]

[0060] Figures 4-5 The diagram shows the error analysis results for the objective lens. The solid blue line represents the analysis result at 670nm, the dashed green line represents the analysis result at 675nm, and the red dashed lines (long and short) represent the analysis result at 665nm.

[0061] Figure 4 This is a diagram showing the objective lens transverse axis error. In each graph, the horizontal axis represents the normalized pupil coordinates, divided into two parts: -1 to +1 (normalized pupil). The vertical axis represents the error value, with a scale extreme of ±5μm. The first row shows the analysis results for the on-axis field of view, the second row for the half-field of view, and the third row for the peripheral field of view. The left column shows the error analysis results in the Y direction, and the right column shows the error analysis results in the X direction.

[0062] Figure 5 This is a graph showing the axial error of the objective lens. The horizontal axis represents the axial error value in mm, and the vertical axis represents the normalized objective lens pupil.

[0063] Figure 6 The actual imaging results of the corneal stroma layer measured by the objective lens are shown, with a scale bar of 100 μm.

[0064] according to Figures 4-5 While achieving a long working distance, the objective lens exhibits the following characteristics: transverse axis error RMS value is less than 0.5 μm in the on-axis field of view at the corresponding numerical aperture and field of view; half-field of view RMS value is less than 0.5 μm; and edge field of view RMS value is less than 1 μm. The axial error PV value is less than 3 μm. These analytical results and... Figure 6 The measured images of the corneal stroma show that the objective lens has high resolution to resolve the fine cellular structures of the cornea.

[0065] When imaging corneal cells, eye gel is instilled onto the objective lens surface, and then a corneal cap is placed over the objective lens surface. During the examination, the corneal cap comes into 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 ophthalmic 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 doctors to examine is 2.8-3.4 mm, which is a significant improvement 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A microscope objective for in vivo corneal confocal tomography, characterized in that The objective lens comprises, in order from the image side to the object side: a first lens group (G1), an aperture (3), a second lens group (G2) and a third lens group (G3), and the objective lens surface covers a corneal cap (9); The first lens group (G1) is used for diverging the incident parallel light, the aperture (3) is used for limiting the diameter of the light spot after divergence, the second lens group (G2) comprises a doublet lens for controlling chromatic aberration in the narrow band spectrum of the light source, and the third lens group (G3) is used for converging the light to the object side focal plane (10); The focal lengths of the lens groups in the objective lens satisfy the following conditions: 0.19 ≤ |F G1 / F G2 |≤0.39 1.5≤|F G1 / F G3 |≤3 wherein F G1 , F G2 , F G3 respectively denote the combined focal lengths of the first (G1), second (G2), and third (G3) mirror groups. The distance between the objective lens surface 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; The refractive index of the corneal cap ranges from 1.2 to 2.

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

3. The microscope objective for in vivo confocal tomography of the cornea according to claim 1, characterized in that The second lens group (G2) comprises a doublet lens composed of a biconvex lens (4) and a meniscus lens (5).

4. The microscope objective for in vivo confocal tomography of the cornea according to claim 1, characterized in that The third lens group (G3) comprises two meniscus lenses (6, 7) and a plano-convex lens (8).

5. The microscope objective for in vivo confocal tomography of the cornea according to claim 1, characterized in that The working wavelength of the objective lens is 670 nm.

6. An in vivo corneal confocal tomographic microscopy system, comprising: It comprises: a detector, a light source, an optical path, a microscopic objective lens as claimed in any one of claims 1-5 and a corneal cap; During the imaging process, the light emitted by the light source enters the microscopic objective lens through the optical path, is focused on the cornea of the eye through the microscopic objective lens and the corneal cap, returns signals of different intensities according to the structure of the corneal cells, and is finally collected by the detector.

7. The in vivo corneal confocal tomography microscope imaging system of claim 6, wherein, The light source is a laser diode.

8. The in vivo corneal confocal tomography microscope imaging system of claim 6, wherein, An ophthalmic gel is used between the microscopic objective lens and the corneal cap.

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