Optical image transfer lens assembly and optical image transfer system for hard tube endoscope

Abstract

The present invention discloses a rigid tube endoscope optical image transfer lens group and a rigid tube endoscope optical image transfer system. The rigid tube endoscope optical image transfer lens group is composed of two glued rod-shaped mirrors with the same structure. The two glued rod-shaped mirrors are symmetrically arranged, and an aperture is provided between the two glued rod-shaped mirrors to form a 1:1 double telecentric image transfer system. The glued rod-shaped mirror includes a Hopkins rod-shaped mirror. The two ends of the Hopkins rod-shaped mirror are respectively glued with a first negative meniscus lens and a second negative meniscus lens. The first negative meniscus lens and the second negative meniscus lens both have convex surfaces facing the aperture. The rigid tube endoscope optical image transfer system includes a plurality of rigid tube endoscope optical image transfer lens groups, and the plurality of rigid tube endoscope optical image transfer lens groups are arranged in any order along the optical axis. In the present invention, an odd number of rigid tube endoscope optical image transfer lens groups are placed along the optical axis to effectively reduce residual aberration and dispersion, improve the imaging quality of the optical system, and facilitate assembly.

Description

Technical Field

[0001] The invention belongs to the technical field of rigid tube endoscopes, and in particular relates to an optical image transfer lens group and an optical image transfer system of a rigid tube endoscope. Background Art

[0002] The optical system of a rigid tube endoscope contains three parts: the imaging objective lens group at the front end, the image transfer lens group at the middle end, and the eyepiece group at the back end. With the continuous development of the rigid tube endoscope industry, higher requirements are also placed on the imaging quality of the endoscope. The traditional rigid tube endoscope optical image transfer lens group will produce large field curvature and astigmatism for imaging, and these aberrations are generally corrected by the objective lens. However, during actual processing and assembly, eccentricity, tilt and other phenomena are inevitable. This aberration correction that only relies on the objective lens will cause the aberration correction of the objective lens to be greatly affected by processing and assembly, and it will be more sensitive. Especially for large-sized endoscopes, they are often composed of multiple groups of optical image transfer lens groups, which are more difficult to assemble. Therefore, there is a need for a solution to effectively correct the aberration of the image transfer lens group.

[0003] The optical image-transmitting lens group of a rigid endoscope is usually composed of two symmetrically placed rod-shaped lenses. Its function is to image the image formed by the objective lens multiple times, so as to increase the working length of the rigid endoscope and meet various special needs. Usually, an odd number of image-transmitting lens groups are used in the optical system of a rigid endoscope to form an upright real image at the eyepiece group of the rigid endoscope.

[0004] Figure 2 The figure shows an early rigid tube endoscope optical image-transmitting lens assembly, which is composed of two double-cemented thin lenses with the aperture located in the middle. The vertical axis aberration of the image-transmitting lens assembly with this structure is well corrected. However, due to the use of thin lenses, its light energy transmittance is low and the lenses are prone to tilt during assembly, so no company uses it now.

[0005] Figure 3 The optical image-transmitting lens assembly of the rigid tube endoscope shown includes two Hopkins rod lenses. This image-transmitting lens assembly has a simple structure, but cannot correct axial chromatic aberration and has poor imaging quality.

[0006] Figure 4 The optical image-transmitting lens assembly of the rigid tube endoscope shown is a symmetrical structure, in which one end of the Hopkins rod lens is glued to a negative lens with a negative focal length, and the thin lens uses optical glass with a high refractive index and high dispersion. Its advantage is its simple structure, and its disadvantage is that it can correct axial chromatic aberration but cannot correct field curvature.

[0007] Figure 5The optical image transfer lens group of the rigid tube endoscope shown is a symmetrical structure. The two ends of the Hopkins rod lens are glued with a thin negative lens with a negative focal length, and the structural parameters of the thin negative lenses at both ends are the same. The thin negative lens uses high refractive index and high dispersion optical glass to correct axial chromatic aberration, but cannot correct field curvature. Summary of the invention

[0008] In order to solve the above problems existing in the prior art, the present invention provides a rigid tube endoscope optical relay lens group and a rigid tube endoscope optical relay system, the purpose of which is to more effectively correct the aberration in the relay system, facilitate installation, and improve image quality.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] An optical image transfer lens group for a rigid tube endoscope is composed of two glued rod-shaped mirrors with the same structure. The two glued rod-shaped mirrors are symmetrically arranged, and an aperture is provided between the two glued rod-shaped mirrors to form a 1:1 double telecentric image transfer system; the glued rod-shaped mirror comprises a Hopkins rod-shaped mirror, and a first negative meniscus lens and a second negative meniscus lens are glued to both ends of the Hopkins rod-shaped mirror, and the first negative meniscus lens and the second negative meniscus lens both have convex surfaces facing the aperture.

[0011] Furthermore, a curvature radius R2 of a bonding surface between the Hopkins rod lens and the first negative meniscus lens is different from a curvature radius of a bonding surface between the Hopkins rod lens and the second negative meniscus lens.

[0012] Furthermore, the first negative meniscus lens, the second negative meniscus lens and the Hopkins rod lens are made of different materials.

[0013] Preferably, the first negative meniscus lens is made of LAF7, the Hopkins rod lens is made of N-BK7, and the second negative meniscus lens is made of QF3.

[0014] Preferably, the first negative meniscus lens is made of LASF18A, the Hopkins rod lens is made of PSK54, and the second negative meniscus lens is made of KZFS1.

[0015] Preferably, the refractive index of the first negative meniscus lens is in the range of 1.78 to 1.91.

[0016] Preferably, the refractive index of the second negative meniscus lens is in the range of 1.58 to 1.61.

[0017] Furthermore, the diameters of the first negative meniscus lens, the second negative meniscus lens and the Hopkins rod mirror are the same.

[0018] The present invention also provides a rigid tube endoscope optical image transfer system, comprising a plurality of rigid tube endoscope optical image transfer lens groups, wherein the plurality of rigid tube endoscope optical image transfer lens groups are arranged in any order along the optical axis.

[0019] Furthermore, the number of the optical image relay lens groups of the rigid tube endoscope is an odd number.

[0020] The present invention has the following beneficial effects:

[0021] The present invention firstly provides an optical image transfer lens group for a rigid tube endoscope, wherein negative meniscus lenses are glued to both ends of a rod lens, and the assembly error can be effectively reduced by gluing.

[0022] Secondly, the present invention provides a rigid tube endoscope optical image transfer system, which is composed of an odd number of rigid tube endoscope optical image transfer lens groups placed along the optical axis, which can effectively reduce residual aberration and dispersion, improve the imaging quality of the optical system, and facilitate assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. 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 the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0024] Figure 1 This is a schematic diagram of an optical image-relay lens assembly for a rigid tube endoscope according to the present invention;

[0025] Figures 2 to 5 They are schematic diagrams of the structures of commonly used hard tube endoscope optical image transfer lens groups with different optical structures in different optical systems in the prior art;

[0026] Figure 6 This is a schematic diagram of the arrangement of a rigid tube endoscope optical image relay lens group of a rigid tube endoscope optical image relay system according to Example 1 of the present invention;

[0027] Figure 7 This is a schematic diagram of the arrangement of a rigid tube endoscope optical image relay lens group of a rigid tube endoscope optical image relay system described in Example 2 of the present invention.

[0028] In the figure:

[0029] 1-first negative meniscus lens 1; 2-Hopkins rod lens; 3-second negative meniscus lens. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0031] like Figure 1 As shown, an optical image transfer lens group of a rigid tube endoscope is composed of two glued rod-shaped mirrors with the same structure. The two glued rod-shaped mirrors are symmetrically arranged, and an aperture is provided between the two glued rod-shaped mirrors to form a 1:1 double telecentric image transfer system; the glued rod-shaped mirror includes a Hopkins rod-shaped mirror 2, and a first negative meniscus lens 1 and a second negative meniscus lens 3 are glued to both ends of the Hopkins rod-shaped mirror 2 respectively.

[0032] Furthermore, the first negative meniscus lens 1 and the second negative meniscus lens 3 both have convex surfaces facing the aperture.

[0033] Furthermore, a curvature radius R2 of a bonding surface between the Hopkins rod lens 2 and the first negative meniscus lens 1 is different from a curvature radius R3 of a bonding surface between the Hopkins rod lens 2 and the second negative meniscus lens 3 .

[0034] Furthermore, the materials of the first negative meniscus lens 1 , the second negative meniscus lens 3 and the Hopkins rod lens 2 are all different.

[0035] Preferably, the first negative meniscus lens is made of LAF7, the Hopkins rod lens is made of N-BK7, and the second negative meniscus lens is made of QF3.

[0036] Preferably, the first negative meniscus lens is made of LASF18A, the Hopkins rod lens is made of PSK54, and the second negative meniscus lens is made of KZFS1.

[0037] Preferably, the refractive index of the first negative meniscus lens is in the range of 1.78 to 1.91.

[0038] Preferably, the refractive index of the second negative meniscus lens is in the range of 1.58 to 1.61.

[0039] Furthermore, the diameters of the first negative meniscus lens 1 , the second negative meniscus lens 3 and the Hopkins rod mirror 2 are the same.

[0040] A rigid tube endoscope optical image transfer system comprises a plurality of rigid tube endoscope optical image transfer lens groups, wherein the plurality of rigid tube endoscope optical image transfer lens groups are arranged in any order along the optical axis.

[0041] Furthermore, the number of the optical image relay lens groups of the rigid tube endoscope is an odd number.

[0042] Example 1

[0043] The rigid tube endoscope optical image transfer system of this embodiment includes three rigid tube endoscope optical image transfer lens groups N arranged along the optical axis, and the distance between the three rigid tube endoscope optical image transfer lens groups N is 6 mm. The three image transfer lens groups can be arranged in any front-to-back order along the optical axis direction, and the residual aberration can be effectively corrected.

[0044] The rigid tube endoscope optical image transfer lens group N is composed of two glued rod-shaped mirrors with the same structure. The two glued rod-shaped mirrors are symmetrically arranged, the distance between the two glued rod-shaped mirrors is 1.2, and an aperture is provided between the two glued rod-shaped mirrors, forming a 1:1 double telecentric image transfer system.

[0045] The glued rod mirror comprises a Hopkins rod mirror 2, and a first negative meniscus lens 1 and a second negative meniscus lens 3 are glued to two ends of the Hopkins rod mirror 2 respectively.

[0046] Among them, the first negative meniscus lens 1 is made of LAF7 with a refractive index of 1.78, a curvature radius R1 of the first surface from the light incident direction is 112.69, a curvature radius R2 of the second surface (gluing surface) is -6.23, and the lens thickness is 1.8mm. The Hopkins rod lens 2 is made of N-BK7 with a curvature radius R2 of the first surface (gluing surface) from the light incident direction is -6.23, a curvature radius R3 of the second surface (gluing surface) is -4.40, and the lens thickness is 25.5mm. The second negative meniscus lens 3 is made of QF3 with a refractive index of 1.58, a curvature radius R3 of the first surface (gluing surface) from the light incident direction is -4.40, a curvature radius R4 of the second surface is -10.68, and the lens thickness is 1.8mm.

[0047] Example 2

[0048] The rigid tube endoscope optical image transfer system of this embodiment includes five rigid tube endoscope optical image transfer lens groups N arranged along the optical axis, and the distance between the five rigid tube endoscope optical image transfer lens groups N is 6 mm. The five image transfer lens groups can be arranged in any front-to-back order along the optical axis direction, and the residual aberration can be effectively corrected.

[0049] The rigid tube endoscope optical image transfer lens group N is composed of two glued rod-shaped mirrors of the same structure, which are symmetrically arranged, with a distance of 0.8 between the two glued rod-shaped mirrors, and an aperture is provided between the two glued rod-shaped mirrors, forming a 1:1 double telecentric image transfer system.

[0050] Among them, the first negative meniscus lens 1 is made of LASF18A, with a refractive index of 1.91, a curvature radius R1 of the first surface from the light incident direction is -16.08, a curvature radius R2 of the second surface (cemented surface) is -5.39, and the lens thickness is 3.07mm. The Hopkins rod lens 2 is made of PSK54, with a curvature radius R2 of the first surface (cemented surface) from the light incident direction is -5.39, a curvature radius R3 of the second surface (cemented surface) is -12.84, and the lens thickness is 84.48mm. The second negative meniscus lens 3 is made of KZFS1, with a refractive index of 1.61, a curvature radius R3 of the first surface (cemented surface) from the light incident direction is -12.84, a curvature radius R4 of the second surface is -34.29, and the lens thickness is 5.76mm.

[0051] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An optical image-relay lens assembly for a rigid tube endoscope, characterized in that: The invention is composed of two glued rod mirrors of the same structure, the two glued rod mirrors are symmetrically arranged, and an aperture is provided between the two glued rod mirrors, so as to form a 1:1 double telecentric image transfer system; the glued rod mirrors include a Hopkins rod mirror, and the two ends of the Hopkins rod mirror are respectively glued with a first negative meniscus lens and a second negative meniscus lens, and the first negative meniscus lens and the second negative meniscus lens both have convex surfaces facing the aperture; the curvature radius R2 of the glued surface of the Hopkins rod mirror and the first negative meniscus lens is different from the curvature radius R2 of the Hopkins rod mirror and the first negative meniscus lens. ns the radius of curvature of the bonding surface between the rod mirror and the second negative meniscus lens; the materials of the first negative meniscus lens, the second negative meniscus lens and the Hopkins rod mirror are all different, the first negative meniscus lens is made of LAF7, the Hopkins rod mirror is made of N-BK7, and the second negative meniscus lens is made of QF3; or the first negative meniscus lens is made of LASF18A, the Hopkins rod mirror is made of PSK54, and the second negative meniscus lens is made of KZFS1.

2. The optical image-relay lens assembly for a rigid tube endoscope according to claim 1, characterized in that: The refractive index range of the first negative meniscus lens is 1.78-1.

91.

3. The optical image-relay lens assembly for a rigid tube endoscope according to claim 1, characterized in that: The refractive index range of the second negative meniscus lens is 1.58-1.

61.

4. The optical image-relay lens assembly for a rigid tube endoscope according to claim 1, characterized in that: The diameters of the first negative meniscus lens, the second negative meniscus lens and the Hopkins rod mirror are the same.

5. An optical image relay system for a rigid tube endoscope, characterized in that: The optical image-transmitting lens assembly comprises a plurality of rigid tube endoscope optical image-transmitting lens assemblies as claimed in any one of claims 1 to 4, wherein the plurality of rigid tube endoscope optical image-transmitting lens assemblies are arranged in any order along the optical axis.

6. The optical image relay system of a rigid tube endoscope according to claim 5, characterized in that: The number of the optical image transfer lens groups of the rigid tube endoscope is an odd number.

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