Optical coupling device for endoscope and endoscope system

Abstract

The utility model relates to optical imaging technology, specifically provide a kind of light coupling device for endoscope, including light source;Still including first lens group, the first lens group includes first positive power lens and second positive power lens, the convex surface of first positive power lens adopts aspheric surface, the convex surface of second positive power lens adopts aspheric surface;Parallel light emitted by light source passes through the first lens group, converges in light convergence plane.The utility model has the advantages of coupling efficiency higher.

Description

Technical Field

[0001] This utility model relates to optical imaging technology, and in particular to an optical coupling device and an endoscope system for endoscopes. Background Technology

[0002] Endoscopes, as important diagnostic and treatment tools, are widely used in modern medicine. After the endoscope is inserted into the body, light emitted from the endoscope's main unit is guided through an optical fiber within the endoscope to illuminate the interior of the body before observation can be performed. To reduce patient discomfort during the procedure, the diameter of the optical fiber needs to be minimized to reduce the outer diameter of the endoscope, while simultaneously ensuring that as much light energy as possible from the main unit is coupled into the optical fiber. However, this results in lower optical coupling efficiency as the diameter of the optical fiber decreases. Summary of the Invention

[0003] To address the shortcomings of the existing technical solutions, this utility model provides an optical coupling device for endoscopes.

[0004] The objective of this utility model is achieved through the following technical solution: An optical coupling device for an endoscope includes a light source; the optical coupling device further includes: The first lens group includes a first positive power lens and a second positive power lens, wherein the convex surface of the first positive power lens is aspherical and the convex surface of the second positive power lens is aspherical. Parallel light emitted from the light source passes through the first lens group and converges at the light convergence surface.

[0005] The present invention also aims to provide an endoscope system, which is achieved through the following technical solution: An endoscope system includes an endoscope and an optical coupling device according to the present invention.

[0006] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. High coupling efficiency; By utilizing the first and second lens groups of this scheme, the optical coupling efficiency is significantly improved. 2. Excellent protective effect; The housing and windows in this solution improve the protection of optical fibers. Attached Figure Description

[0007] The disclosure of this utility model will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are merely illustrative of the technical solutions of this utility model and are not intended to limit the scope of protection of this utility model. In the drawings: Figure 1This is a schematic diagram of the optical coupling device according to the present invention; Figure 2 This is a partial structural schematic diagram of the optical coupling device according to this utility model; Figure 3 This is a schematic diagram based on the effect of this utility model.

[0008] In the attached diagram, 11-first lens group, 111-first positive power lens, 112-second positive power lens, 12-second lens group, 121-third positive power lens, 122-fourth positive power lens, 21-light source, 22-filter, 31-optical fiber, 32-outer shell, 33-window. Detailed Implementation

[0009] Figures 1-3 The following description illustrates optional embodiments of the present invention to teach those skilled in the art how to implement and reproduce it. For the purpose of teaching the technical solutions of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art should understand that variations or substitutions derived from these embodiments will be within the scope of the present invention. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the present invention. Therefore, the present invention is not limited to the following optional embodiments, but is defined only by the claims and their equivalents.

[0010] Example 1

[0011] This embodiment provides an optical coupling device for an endoscope, such as... Figure 1 As shown, the optical coupling device includes: Light source 21 and light converging surface, such as the end face of optical fiber 31.

[0012] The first lens group 11 includes a first positive power lens 111 and a second positive power lens 112. The convex surface of the first positive power lens 111 is aspherical. The convex surface of the second positive power lens 112 is aspherical.

[0013] Parallel light emitted from light source 21 passes through the first lens group 11 and converges at the light convergence surface.

[0014] To improve optical coupling efficiency, the first positive power lens 111 is further configured as a plano-convex lens, with its planar surface facing away from the light converging surface and its convex surface facing away from the light source 21. The second positive power lens 112 is also a plano-convex lens, with its convex surface facing away from the light converging surface and its planar surface facing away from the light source 21; the convex surface is an even-order aspherical surface.

[0015] To further collimate the emitted light from the collimating light source 21, the optical coupling device also includes: The second lens group 12 includes a third positive power lens 121 and a fourth positive power lens 122. The third positive power lens 121 is a plano-convex lens, with its flat surface facing away from the light converging surface and its convex surface being aspherical, and facing away from the light source 21. The fourth positive power lens 122 is a plano-convex lens, with its convex surface being aspherical, and its flat surface facing away from the light converging surface, and its plane facing away from the light source 21.

[0016] The light emitted by the light source 21 passes through the second lens group 12 and becomes the parallel light.

[0017] To further improve optical coupling efficiency, all four positive power lenses have aspherical surfaces that are even-order aspherical surfaces.

[0018] To further improve protection efficiency, such as... Figure 2 As shown, the optical coupling device further includes: The optical fiber 31 is disposed inside the housing 32.

[0019] A window 33 is disposed at the end of the housing 32. The converging light emitted from the first lens group 11 passes through the window 33 and enters the optical fiber 31.

[0020] Example 2

[0021] An example of the application of an endoscope optical coupling device in an endoscope system according to Embodiment 1 of this utility model.

[0022] In this application example, the endoscope system includes an optical coupling device and an endoscope.

[0023] The technical principle of optical coupling in this invention is as follows: According to the principle of optical spread, the product of the area of ​​a light beam passing through a certain cross section and the solid angle of the light ray direction at that cross section is a constant, that is: G=n 2 ·A·Ω=2πA[1-cos(0.5α)].

[0024] Where n is the refractive index of the medium, A is the area of ​​the beam cross section, Ω is the solid angle relative to the cross section, and α is the beam divergence angle.

[0025] To obtain a smaller light spot, it is necessary to increase the refractive index of the medium and the solid angle of the interface. However, the range of refractive index values ​​is limited, so it is more necessary to control the size by increasing the solid angle. The beam in front of the focusing lens is usually collimated. The size of the solid angle of the focusing lens group for collimating the straight beam depends on the focal length of the lens group. The smaller the focal length, the larger the solid angle. Although increasing the solid angle can reduce the size of the focused light spot, an excessively large solid angle will result in an excessively large incident angle of light on the end face of the light guide fiber. If the incident angle exceeds the numerical aperture (NA) range of the light guide fiber, the excess light will still not be able to couple into the light guide fiber. Therefore, it is necessary to comprehensively consider the fiber aperture and the light spot size to design the optical structure so that the light guide beam can be efficiently emitted after being connected to the host.

[0026] The focusing lens group uses even-order aspherical optical surfaces. Aspherical lenses can efficiently calibrate aberrations to improve the quality and distribution of the beam.

[0027] In this embodiment, the light source is an LED with a divergence full width at half maximum (FWHM) α = 110 degrees and a light-emitting area A = 4.8 mm. 2 After being collimated by the second lens group 12, the LED emits a collimated beam with a beam radius of 34mm, which is then converged by the first lens group 11 and enters the lighting optical fiber 31.

[0028] like Figure 1 As shown, the first lens group adopts a two-piece structure. The first positive power lens 111 is a plano-convex lens, with its flat surface facing away from the optical fiber 31 and its convex surface being aspherical, facing away from the light source 21. The second positive power lens 112 is also a plano-convex lens, with its convex surface being aspherical, facing away from the optical fiber 31 and its flat surface facing away from the light source 21. This design facilitates lens positioning and the design of the matching lens barrel and frame. Furthermore, the two-piece structure, compared to a single-piece structure, can more effectively reduce the influence of aberrations to decrease the size of the converging light spot. Using an aspherical surface can effectively reduce the influence of edge aberrations, thereby controlling the size and uniformity of the light spot.

[0029] The second lens group 12 adopts a two-element structure. The third positive power lens 121 is a plano-convex lens, with its flat surface facing away from the optical fiber 31 and its convex surface being aspherical, and facing away from the light source 21. The fourth positive power lens 122 is a plano-convex lens, with its convex surface being aspherical, and its flat surface facing away from the optical fiber 31 and the light source 21.

[0030] like Figure 2 As shown, the optical fiber 31 is disposed inside the cylindrical housing 32. A K9 glass window 33 is disposed at the end of the housing 32, and the converging light emitted from the first lens group 11 passes through the window 33 and enters the optical fiber 31.

[0031] The effective aperture of the last surface of the second positive optical power lens 112 is M, the distance from this surface to the incident end face of the illumination fiber 31 is L, the aperture of the illumination fiber 31 is D, and the total angle α of the light focused onto the end face of the illumination fiber 31 is... f =tan -1 (M / L).

[0032] The light guide rod on the endoscope is inserted into a predetermined position in the endoscope's light source unit. The light guide rod (a collective term for the housing 32, optical fiber 32, and window 33) receives the illumination light converged by the first lens group 11 in the light source unit 21. The numerical aperture NAf of the optical fiber 31 is 0.64, meaning that the incident angle on the end face of the optical fiber 31 is less than α. f (79.58°), meeting the coupling conditions of fiber optic 31, it enters fiber optic 31 for transmission. The optical aperture of the fiber optic 31 used is D1 = 2.4mm. According to the principle of optical spread, the optical spread of light source 21 must be equal to the optical spread on the surface of fiber optic 31, G led =G f .

[0033] Optical expansion of light emitted by light source 21: G led =2πA led [1-cos(0.5α led )]=2π·4.8·(1-cos55 o =12.86.

[0034] The corresponding spread of the minimum spot size on the 31-end face of the optical fiber: G f =2πA f [1-cos(0.5α f )]=2π 2 ·1 2 ·[1-cos(0.5α f )]=12.86.

[0035] According to calculations, to ensure that the light spot size on the surface of fiber 31 is less than or equal to 2.4 mm, the optical fiber diameter should be 113.66 mm. o ≤α f .

[0036] The calculated optical extension and fiber coupling conditions are contradictory; that is, it is impossible to simultaneously satisfy a sufficiently small focused spot size and the angle of all focused rays meeting the fiber coupling angle. Therefore, a balance needs to be found between the two, sacrificing either the spot size or the coupling angle to allow more light energy to be transmitted into fiber 31. In the simulation, by controlling the incident angle and the spot size on the end face of fiber 31, the optical system shown in the table below was designed through simulation analysis.

[0037]

[0038] In this system, L = 15.035 mm, M = 27.88 mm, i.e., α f =85.67 degrees, meaning that this system sacrifices more of the surface area of ​​fiber 31 to allow more light reaching the surface of fiber 31 to couple into the fiber 31. The energy distribution on the plane where the end face of fiber 31 is located is as follows. Figure 3 As shown, 48.248% of the energy is contained within the 2.4mm fiber, of which approximately 92% of the light meets the fiber coupling conditions, meaning that 44.34% of the light emitted from the first lens group 11 is coupled into the fiber 31. Compared with existing technologies, this significantly improves optical coupling efficiency.

Claims

1. An optical coupling device for an endoscope, comprising a light source; characterized in that, The optical coupling device further includes: The first lens group includes a first positive power lens and a second positive power lens, wherein the convex surface of the first positive power lens is aspherical and the convex surface of the second positive power lens is aspherical. Parallel light emitted from the light source passes through the first lens group and converges at the light convergence surface.

2. The optical coupling device according to claim 1, characterized in that, The first positive power lens is a plano-convex lens, with the plane facing away from the light converging surface and the convex surface facing away from the light source. The second positive power lens is a plano-convex lens, with the convex surface facing away from the light converging surface and the plane facing away from the light source. The convex surface is an even-order aspherical surface.

3. The optical coupling device according to claim 1, characterized in that, Within the optical receiving area, the light spot energy ratio is greater than 45%, and within the optical receiving area, more than 80% of the light is coupled into the optical fiber.

4. The optical coupling device according to claim 1, characterized in that, The optical coupling device further includes: The second lens group includes a third positive power lens and a fourth positive power lens. The third positive power lens is a plano-convex lens with its plane facing away from the light converging surface and its convex surface being aspherical and facing away from the light source. The fourth positive power lens is a plano-convex lens with its convex surface being aspherical and facing away from the light converging surface, and its plane facing away from the light source. The light emitted by the light source passes through the second lens group and becomes the parallel light.

5. The optical coupling device according to claim 4, characterized in that, The aspherical surface of a positive power lens is an even-order aspherical surface.

6. The optical coupling device according to claim 1, characterized in that, The optical coupling device further includes: The housing contains an optical fiber disposed within it. A window is disposed at the end of the housing, through which the converging light emitted from the first lens group passes and enters the optical fiber.

7. The optical coupling device according to claim 6, characterized in that, The window panes are made of K9 glass.

8. The optical coupling device according to claim 6, characterized in that, The diameter of the second positive optical power lens is 27.88 mm, the distance between the plane of the second positive optical power lens and the incident end face of the optical fiber is 15.035 mm, and the aperture of the optical fiber is 2.4 mm.

9. An endoscope system, comprising an endoscope; characterized in that, The endoscope system further includes the optical coupling device according to any one of claims 1-8.

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