阅读说明：本技术 内窥镜物镜变焦光学系统 (Endoscope objective lens zoom optical system ) 是由 王立强 石岩 于 2019-11-29 设计创作，主要内容包括：本发明公开了一种内窥镜物镜变焦光学系统,沿光学系统的光轴从物方至像方依次包括：具有负的光焦度的固定透镜组,及具有正的光焦度的变焦透镜组,变焦透镜组通过沿所述光轴的移动可以改变内窥镜物镜变焦光学系统的焦距。本发明涉及一种高性能内窥镜物镜光学系统,该系统具有足够大的放大倍数,能够在内窥镜下进行500-1000倍的显微放大观察；在普通观察时,内窥镜镜头视场角可以达到140°,可对人体病变组织进行精准的成像诊断。(The invention discloses an endoscope objective lens zooming optical system, which comprises the following components in sequence from an object side to an image side along an optical axis of the optical system: a fixed lens group having negative power, and a zoom lens group having positive power, the zoom lens group being movable along the optical axis to change a focal length of the endoscope objective zoom optical system. The invention relates to a high-performance endoscope objective optical system, which has a large enough magnification factor and can carry out microscopic magnification observation of 500-1000 times under an endoscope; during ordinary observation, the field angle of the endoscope lens can reach 140 degrees, and accurate imaging diagnosis can be performed on human pathological tissues.)

1. An endoscope objective zoom optical system comprising, in order from an object side to an image side along an optical axis of the optical system: a fixed lens group (G1) having negative power;

a zoom lens group (G2) having positive optical power, the focal length of the endoscope objective zoom optical system being changeable by movement thereof along the optical axis.

2. The endoscope objective zoom optical system according to claim 1, characterized in that: the fixed lens group (G1) includes a first lens (R1), a second lens (R2) and a third lens (R3) from an object side to an image side, and the zoom lens group (G2) includes a fourth lens (R4), a fifth lens (R5), a sixth lens (R6), a seventh lens (R7) and an eighth lens (R8); wherein: the first lens element (R1) is a plano-concave negative lens element facing the object side, the second lens element (R2) is a concave-convex negative lens element having a convex surface facing the image side, the third lens element (R3) is a plano-convex positive lens element facing the object side, the fourth lens element (R4) is a double-convex positive lens element, the fifth lens element (R5) is a plano-convex positive lens element facing the object side, the sixth lens element (R6) is a meniscus negative lens element having a concave surface facing the object side, the seventh lens element (R7) is a meniscus negative lens element having a convex surface facing the object side, and the eighth lens element (R8) is a double-convex positive lens element.

3. The endoscope objective zoom optical system according to claim 2, characterized in that: an aperture stop (S) is further disposed between the third lens (R3) and the fourth lens (R4).

4. The endoscope objective zoom optical system according to claim 2, characterized in that: the fifth lens (R5) is cemented with the sixth lens (R6), and the seventh lens (R7) is cemented with the eighth lens (R8).

5. The endoscope objective zoom optical system according to any one of claims 1 to 4, characterized in that: the adjustable range delta d of the zoom lens group (G2) along the optical axis of the optical system and the total length TTL of the endoscope objective lens zoom optical system satisfy the following ratio: delta d/TTL is more than or equal to 4.4 and less than or equal to 5.1.

6. The endoscope objective zoom optical system according to any one of claims 1 to 4, characterized in that: when the endoscope objective lens zoom optical system is used for magnifying observation, the ratio of the distance d between the fixed lens group (G1) and the zoom lens group (G2) and the overall focal length f of the system is satisfied: d/f is more than or equal to 2.4 and less than or equal to 2.8; focal length f of zoom lens group (G2)₁And the ratio of the integral focal length f of the system is satisfied: f is not less than 2.2₁/f≤2.6。

7. The endoscope objective zoom optical system according to any one of claims 1 to 4, characterized in that: when the endoscope objective lens zoom optical system is used for ordinary observation, the ratio of the distance d between the fixed lens group (G1) and the zoom lens group (G2) and the overall focal length f of the system is satisfied: d/f is more than or equal to 0.6 and less than or equal to 1; focal length f of zoom lens group (G2)₁And the ratio of the integral focal length f of the system is satisfied: f is not less than 3.5₁/f≤3.9。

8. The endoscope objective zoom optical system according to any one of claims 1 to 4, characterized in that: the fixed lens group (G1) includes a lens having a refractive index greater than 1.9, and the variable focus lens group (G2) also includes a lens having a refractive index greater than 1.9.

Technical Field

The present invention relates to an endoscope objective lens zoom optical system, and more particularly, to a bifocal objective lens zoom optical system for use in an endoscope for medical diagnosis.

Background

As a clinical application of a high-performance endoscope, the dual-function requirements of microscopic magnification observation and large-field-of-view high-definition imaging exist. In particular, for the observation and diagnosis of early diseases in the human body, endoscopes integrating magnification observation and high-definition imaging are increasingly widely used.

The diagnosis gold standard of the digestive tract tumor is electronic endoscopy, namely, the electronic endoscope is adopted to observe a mucous membrane image, and sampling, staining and pathological diagnosis are carried out on an abnormal area, and the method has the defects of omission, diffusion, time consumption and the like.

How to perform real-time pathological diagnosis in vivo is always the ultimate goal of endoscopic technology. Confocal microscopy and optical microscopy are two main technical means for clinical application at present, and can carry out 1000x (confocal) or 500 plus 1000x (optical amplification) microscopic imaging on tissues such as adenoma, polyp, capillary vessel and the like, thereby realizing diagnosis, surgical planning and curative effect reexamination of early cancer.

However, such endoscope devices are expensive, confocal microscopy is a probe type structure, and needs to enter a body through a forceps channel of a standard endoscope, so that diagnosis and subsequent operations cannot be performed simultaneously.

The 500-plus-1000-x endomicroscopy is of an integrated structure and can be used for simultaneously carrying out microscopic imaging and operation, so that the method can be further popularized and can realize tumor screening. However, such endoscopes require an objective optical system with a bifocal imaging function, i.e., a zoom function, and can achieve bifocal imaging with microscopic magnification and high-definition wide-angle by adjusting a lens group. In microscopic magnification observation (hereinafter, collectively referred to as "magnification observation"), the distance from the objective lens to the object position (hereinafter, collectively referred to as "object distance") is short, typically about 0mm to 2 mm. In high-definition wide-angle observation (hereinafter collectively referred to as "normal observation"), the object distance is usually much larger than 2mm, such as 5-100 mm.

Disclosure of Invention

The existing endoscope has the defects of more lenses, usually more than 10 lenses, small microscopic magnification field of view and the like when the existing endoscope realizes the zooming function. The invention aims to provide an endoscope objective lens zoom optical system aiming at the defects of the prior art, which has a large enough magnifying visual field and multiple and can carry out magnifying observation under an endoscope; during ordinary observation, the field angle of the endoscope lens can reach 140 degrees, the position of a human body is observed and monitored, the number of the endoscope lens is small, and the complexity of the system is reduced.

The technical problem solved by the invention is mainly realized by adopting the following scheme:

an endoscope objective zoom optical system comprising, in order from an object side to an image side along an optical axis of the optical system:

a fixed lens group having negative power;

a zoom lens group having positive power for changing a focal length of the endoscope objective zoom optical system by movement thereof along the optical axis.

In the foregoing aspect, it is preferable that, from the object side to the image side, the fixed lens group includes a first lens, a second lens, and a third lens, and the zoom lens group includes a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens; wherein: the first lens is a plano-concave negative lens with the plane facing the object side, the second lens is a concave-convex negative lens with the convex surface facing the image side, the third lens is a plano-convex positive lens with the plane facing the object side, the fourth lens is a double-convex positive lens, the fifth lens is a plano-convex positive lens with the plane facing the object side, the sixth lens is a meniscus negative lens with the concave surface facing the object side, the seventh lens is a meniscus negative lens with the convex surface facing the object side, and the eighth lens is a double-convex positive lens.

More preferably, an aperture stop is further disposed between the third lens and the fourth lens. More preferably, the fifth lens is cemented with the sixth lens, and the seventh lens is cemented with the eighth lens.

In addition, according to a preferred embodiment of the present invention, the following conditional expression (1) is satisfied.

2.4≤d/f≤2.8 (1)

When the endoscope objective lens zoom optical system is viewed in a magnified manner, d is the distance between the fixed lens group (G1) and the zoom lens group (G2), and f is the focal length of the entire system.

In addition, according to a preferred embodiment of the present invention, the following conditional expression (2) is satisfied.

0.6≤d/f≤1 (2)

Here, when the endoscope objective lens zoom optical system is in a normal view, d is a distance between the fixed lens group (G1) and the zoom lens group (G2), and f is a system overall focal length.

In addition, according to a preferred embodiment of the present invention, the following conditional expression (3) is satisfied.

2.2≤f₁/f≤2.6 (3)

Here, when the endoscope objective zoom optical system is under magnification observation, f₁F is the focal length of the zoom lens group and the whole focal length of the system.

In addition, according to a preferred embodiment of the present invention, the following conditional expression (4) is satisfied.

3.5≤f₁/f≤3.9 (4)

Here, when the endoscope objective zoom optical system is in normal observation, f₁F is the focal length of the zoom lens group and the whole focal length of the system.

In addition, according to a preferred embodiment of the present invention, the following conditional expression (5) is satisfied.

4.4≤Δd/TTL≤5.1 (5)

Where Δ d is an adjustable range of the zoom lens group of the endoscope objective system along the optical axis, and TTL is a total length of the endoscope objective optical system.

The endoscope objective lens zooming optical system according to the present invention has the following effects:

when the endoscope objective lens zooming optical system is used for magnifying observation, the field angle corresponding to the object side is reduced, which is beneficial to aberration correction, and when the endoscope objective lens zooming optical system is used for ordinary observation, a larger field of view can be obtained; in addition, the focal length of the endoscope objective lens optical system can be changed by moving the zoom lens group along the optical axis, so that the endoscope objective lens zoom optical system has a bifocal imaging function, the object side can be magnified and observed and the common observation can be realized, the imaging quality is good, and the application requirements of medical diagnosis and treatment and the like can be met.

Drawings

In order to illustrate the invention more clearly, the drawings that are needed in the description of the embodiments will be briefly described below.

FIGS. 1A-1B are schematic diagrams of the layout of the optical elements of the zoom optical system of the objective lens of the endoscope for normal observation and enlarged observation, respectively;

FIGS. 2A to 2B are respectively a view showing an ordinary observation and an enlarged observation of the zoom optical system for an endoscope objective lens according to the present invention,

measured field curvature and distortion aberrations;

FIGS. 3A-3B are MTFs respectively measured during normal observation and enlarged observation of the objective zoom optical system of the endoscope provided by the present invention;

detailed description of the invention

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described more clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are a part of the present invention, but not all embodiments.

Fig. 1 is a cross-sectional configuration diagram showing an endoscope objective zoom optical system according to the present embodiment. Here, fig. 1A is a cross-sectional configuration diagram showing an endoscope objective zoom optical system in a normal observation state. Fig. 1B is a sectional configuration diagram showing the zoom optical system of the endoscope objective lens in a magnified state.

The fixed lens group G1 has negative power. The fixed lens group closest to the object side adopts negative focal power, so that the field angle range under common observation can be effectively improved.

The zoom lens group G2 has positive optical power for changing the focal length of the endoscope optical system by its movement along the optical axis. For example, the zoom lens group moves close to the image plane IMG along the optical axis, and the focal length of the endoscope objective zoom optical system can be changed.

The endoscope objective lens zoom optical system provided in this embodiment is configured such that the corresponding field angle increases when the zoom lens group G2 is farthest from the object side, by including the fixed lens group G1 having negative power as the lens group closest to the object side and the zoom lens group G2 having positive power as the other lens group behind the fixed lens group G1,

when the zoom lens group G2 is closest to the object side, the corresponding angle of view decreases; in addition, the focal length of the zoom optical system of the endoscope objective lens can be changed by moving the zoom lens group G2 along the optical axis, the object side can be magnified and observed, the imaging quality is good, the field range is wide during ordinary observation, and the application requirements of medical diagnosis and treatment and the like can be met.

In the above technical solution, in order to realize enlarged observation and general observation, optionally, the fixed lens group G1 includes a refractive index N₁A lens larger than 1.9, and a variable focus lens group G2 including a refractive index N₂A lens greater than 1.9.

Optionally, the fixed lens group G1 includes a first lens R1, a second lens R2, and a third lens R3; a protective window glass L1 may be added to the object side of the first lens R1, and the zoom lens group G2 includes a fourth lens R4, a fifth lens R5, a sixth lens R6, a seventh lens R7, and an eighth lens R8. The endoscope objective optical system with negative and positive focal powers can be formed by eight lenses, and the endoscope objective optical system is simple and compact in structure and low in cost.

Alternatively, an aperture stop may be provided at about the center of the endoscope objective optical system, such as the aperture stop S provided between the third lens R3 and the fourth lens R4, which is effective in suppressing off-axis rays in the endoscope objective optical system.

Alternatively, the zoom lens group G2 may be selected from a cemented lens group, such as a lens group formed by a fifth lens R5 cemented with a sixth lens R6, and a lens group formed by a seventh lens R7 cemented with an eighth lens R8 to better correct chromatic aberration during aberration correction.

Aiming at the limitation of the scope of the magnifying observation visual angle of the endoscope objective optical system, the object can be magnified and observed in a proper visual field, and optionally, the object height of the invention when the object side target is magnified and observed by the objective optical system meets the following formula

0.6mm≤y≤0.64mm (a)

If the field of view of ordinary observation is larger than 0.64mm, a large distortion (distortion) occurs when the object on the object side is imaged. In order to avoid large deformation of the object-side imaging, optionally, the object height at the normal observation position of the endoscope objective optical system of the present invention satisfies the following formula:

39mm≤y≤43mm (b)

in practical application, the formula (a) and the formula (b) are combined to realize magnifying observation and common observation,the degree of deformation (degree of distortion) of the object-side imaging can be effectively controlled. The distance d between the fixed lens group G1 and the variable focus lens group G2, the overall focal length f of the system and the focal length f of the variable focus lens group defined in the scheme of the invention₁Under the constraint of the relationship, the definition of the object height further confirms that when the object distance is 0 (magnified observation) and 15mm (ordinary observation), the zoom optical system provided by the invention achieves the optimal performance of the attached figures 2A-3B.

In the endoscope objective lens zoom optical system, when the moving range of the zoom lens group G2 is too small, it is difficult to achieve a desired magnification ratio, but when the moving range is too large, it is difficult to correct aberrations to obtain high image quality. Optionally, in zooming from normal observation to enlarged observation, a ratio of an adjustable range Δ d of the zoom lens group G2 along the optical axis to a total length TTL of the zoom optical system satisfies the following equation

4.4≤Δd/TTL≤5.1 (c)