Optical imaging systems and endoscopes

Abstract

The present invention discloses an optical imaging system and an endoscope. The optical imaging system includes a first lens group, a tunable lens, and a second lens group, arranged sequentially from the object side to the image side. The first lens group and the second lens group each include a plurality of lenses, and the tunable lens is equipped with a control board for applying different driving voltages to the tunable lens to adjust the curvature radius of the tunable lens. The optical imaging system and endoscope of the present application can solve the problem of the focusing mechanism of the optical imaging system of the endoscope in the related art being large in size, complex in structure, and inconvenient for achieving continuous and rapid focusing.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more specifically, to an optical imaging system and an endoscope. Background Technology

[0002] Electronic endoscopes, as medical diagnostic tools and minimally invasive surgical instruments, are inserted into the body through natural orifices or minimally invasive incisions. They utilize a miniature imaging system and illumination source at the tip to capture high-resolution images of internal organs and tissues, transmitting these images via cable to an external monitor for real-time observation, diagnosis, or surgery by physicians. Electronic endoscopes are widely used in laparoscopy, gastroscopy, colonoscopy, bronchoscopy, cystoscopy, and other fields. Compared to traditional optical endoscopes, they offer advantages such as higher image clarity, higher integration, and wider application scenarios.

[0003] Autofocus electronic endoscopes hold significant importance in the medical field. In clinical diagnosis and minimally invasive surgery, doctors need to capture images of different depths within the body at varying working distances to pinpoint the exact location of lesions and identify microstructural pathological features. Currently, most medical electronic endoscopes use fixed-focus lenses, requiring an expanded depth of field to meet these demands. However, depth of field and resolution are mutually exclusive; a greater depth of field results in lower resolution. Therefore, existing fixed-focus electronic endoscopes must balance high image quality with a large depth of field. Applying autofocus technology to electronic endoscopes enables the rapid and accurate capture of high-resolution images of internal organs and tissues. This technology significantly improves the efficiency of doctors' operations during diagnosis and treatment, and makes the observation and analysis of complex cases more convenient and reliable. The introduction of autofocus electronic endoscopes provides crucial technical support for modern medical practices such as minimally invasive surgery and early detection and timely treatment of lesions, significantly contributing to improved patient outcomes and quality of life.

[0004] Related technologies have proposed a dual-focus imaging scheme that uses a control cam or drive motor at the handle to pull a steel wire to adjust the position of the lens, thereby achieving near-point imaging and far-point imaging. However, the focusing mechanism is large in size and complex in structure, which is not conducive to miniaturization and automation. Moreover, the focusing accuracy is affected by the mechanical precision, making it difficult to achieve fast, continuous and accurate focusing. Summary of the Invention

[0005] The main objective of this invention is to provide an optical imaging system and an endoscope to solve the problems of large size, complex structure, and inconvenience in achieving continuous and rapid focusing in the focusing mechanism of optical imaging systems of endoscopes in related technologies.

[0006] According to one aspect of the present invention, an optical imaging system is provided, comprising a first lens group, a tunable lens, and a second lens group arranged sequentially from the object side to the image side, wherein...

[0007] The first lens group consists of a first lens, a second lens, and a third lens arranged sequentially from the object side to the image side; the object side of the first lens is convex and the image side is concave; the object side of the second lens is convex and the image side is concave; both the image side and the object side of the third lens are convex; the optical power of the first lens and the second lens are both negative.

[0008] The second lens group consists of a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged sequentially from the object side to the image side; the object side and image side of the fourth lens are both convex; the fifth lens and the sixth lens are cemented together to form a cemented doublet lens, the object side and image side of the fifth lens are both concave; the object side and image side of the sixth lens are both convex; the object side and image side of the seventh lens are both convex.

[0009] The tunable lens is equipped with a control board, which is used to apply different driving voltages to the tunable lens to adjust the radius of curvature of the tunable lens.

[0010] Furthermore, the optical imaging system satisfies the following relationship: ,in, The distance between the object-side surface of the tunable lens and the object-side surface of the first lens group on the optical axis. The distance between the image-side surface of the tunable lens and the image-side surface of the second lens group on the optical axis.

[0011] Furthermore, the optical imaging system satisfies the following relationship: ,in, The optical power of the tunable lens, The effective focal length of the optical imaging system is given.

[0012] Furthermore, the optical imaging system also includes an aperture stop located between the first lens group and the tunable lens, and the optical imaging system satisfies the following relationship: ,in, The distance between the aperture and the side of the first lens group closest to the object on the optical axis. The distance between the aperture and the object side of the tunable lens on the optical axis.

[0013] Furthermore, the optical imaging system satisfies the following relationship: ,in, The combined focal length of the first lens and the second lens. The effective focal length of the optical imaging system is given.

[0014] Furthermore, the optical imaging system satisfies the following relationship: ,in, The focal length of the third lens is... Let be the effective focal length of the optical imaging system. Further, the optical imaging system satisfies the following relationship: ,in, Let be the radius of curvature of the object-side surface of the fifth lens. The radius of curvature of the image-side surface of the sixth lens is given.

[0015] Furthermore, the optical imaging system satisfies the following relationship: ,in, The focal length of the fifth lens is... The focal length of the sixth lens is... The combined focal length of the fifth lens and the sixth lens.

[0016] Furthermore, the optical imaging system satisfies the following relationship: ,in, The focal length of the seventh lens is... The effective focal length of the optical imaging system is given.

[0017] On the other hand, this application also provides an endoscope that includes the aforementioned optical imaging system.

[0018] In this invention, an tunable lens is incorporated into the optical imaging system. During use, different driving voltages can be applied to the tunable lens via a control board, thereby altering its radius of curvature and consequently its optical power within the system. Higher driving voltages result in a smaller radius of curvature, leading to closer object distances for autofocus and clearer observation of minute objects. This facilitates real-time, rapid focusing and ultimately improves the imaging quality of the optical imaging system. Furthermore, the tunable lens in this invention requires only a simple control board to adjust its radius of curvature, eliminating the need for complex mechanical traction structures. This allows for direct integration of the optical imaging system into the endoscope's front end, addressing the issues of large size, complex structure, discontinuous focusing, and slow focusing speed in traditional endoscope optical imaging systems. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 This is a schematic diagram of the structure of the optical imaging system disclosed in the embodiments of this application;

[0021] Figure 2 This is a schematic diagram showing the change in distance d between the optical imaging system and the observed object when the control board of the optical imaging system disclosed in this application applies high (a), medium (b), and low (c) voltages to the tunable lens;

[0022] Figure 3 This is a graph of the optical modulation function of the optical imaging system disclosed in this application when the distance between the system and the object being observed is 150 mm.

[0023] Figure 4 This is a graph of the optical modulation function of the optical imaging system disclosed in this application when the distance between the system and the object being observed is 110 mm.

[0024] Figure 5 This is a graph of the optical modulation function of the optical imaging system disclosed in this application when the distance between the system and the object being observed is 70 mm.

[0025] Figure 6 This is a graph of the optical modulation function of the optical imaging system disclosed in this application when the distance between the system and the object being observed is 40 mm.

[0026] Figure 7 This is a graph of the optical modulation function of the optical imaging system disclosed in this application when the distance between the system and the object being observed is 20 mm.

[0027] Figure 8 This is a graph of the optical modulation function of the optical imaging system disclosed in this application when the distance between the system and the object being observed is 10 mm.

[0028] Figure 9 This is a distortion curve diagram of the optical imaging system disclosed in the embodiments of this application;

[0029] Figure 10 This is a field curvature diagram of the optical imaging system disclosed in the embodiments of this application;

[0030] Figure 11 This is a relative illumination curve of the optical imaging system disclosed in the embodiments of this application.

[0031] The above figures include the following reference numerals:

[0032] 10. First lens; 20. Second lens; 30. Third lens; 40. Fourth lens; 50. Fifth lens; 60. Sixth lens; 70. Seventh lens; 80. Aperture stop; 90. Adjustable lens; 100. Control panel; 110. Protective glass plate. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0036] See Figures 1 to 2 As shown, this application provides an optical imaging system for use in endoscopes. The optical imaging system comprises a first lens group, a tunable lens 90, and a second lens group arranged sequentially from the object side to the image side. Both the first and second lens groups include several lenses, with both the object-side and image-side surfaces of the lenses being spherical. The tunable lens 90 is equipped with a control board 100, which applies different driving voltages to the tunable lens 90 to adjust its radius of curvature.

[0037] It should be noted that the tunable lens 90 in this application is a lens with a variable radius of curvature. In actual use of the optical imaging system, different driving voltages can be applied to the tunable lens 90 via the control board 100 as needed, thereby changing the radius of curvature of the tunable lens 90 and thus altering its optical power within the optical imaging system. During adjustment, a higher driving voltage on the tunable lens 90 results in a smaller radius of curvature, leading to a closer object distance for autofocus, clearer observation of minute objects, and easier real-time, rapid focusing, ultimately improving the imaging quality of the optical imaging system. Furthermore, the tunable lens 90 in this application only requires a simple control board 100 to achieve radius of curvature adjustment, eliminating the need for complex mechanical traction structures. This allows for direct integration of the optical imaging system into the front end of an endoscope, solving the problems of large size, complex structure, discontinuous focusing, and slow focusing speed in traditional endoscope optical imaging systems.

[0038] Specifically, the first lens group in this application consists of a first lens 10, a second lens 20, and a third lens 30 arranged sequentially from the object side to the image side. The object side of the first lens 10 is convex, and the image side is concave; the object side of the second lens 20 is convex, and the image side is concave; both the image side and the object side of the third lens 30 are convex. The optical angles of the first lens 10 and the second lens 20 are negative. The first lens 10 and the second lens 20 in this application are both meniscus lenses, which can be used to quickly and smoothly converge the propagation angle of light rays in a large field of view. This effectively reduces large field-of-view aberrations while avoiding an excessively large light exit angle that would increase the aperture of the optical imaging system. This facilitates the miniaturization and integration of the optical imaging system and better adapts to the limitations of the endoscope's front port diameter. The third lens 30 is a biconvex lens, which facilitates the convergence of light rays.

[0039] Furthermore, the optical imaging system satisfies the following relationship: ,in, The combined focal length of the first lens 10 and the second lens 20 This is the effective focal length of the optical imaging system. For example, Possible values ​​include 0.56, 0.57, 0.58, 0.59, 0.60, 0.62, 0.64, 0.66, and 0.68. This application utilizes... This ensures that the light rays of the large field of view of the optical imaging system converge continuously and smoothly, while also ensuring that the curvature of the first lens 10 and the second lens 20 is moderate, making it easier to process and produce the optical imaging system.

[0040] Furthermore, the optical imaging system satisfies the following relationship: ,in, The focal length of the third lens 30. This is the effective focal length of the optical imaging system. For example, Possible values ​​include 1.26, 1.28, 1.30, 1.32, and 1.34. This application utilizes... It can effectively compensate for spherical aberration and astigmatism in the entire optical imaging system.

[0041] Furthermore, the optical imaging system of this application satisfies the following relationship: ,in, The distance between the object-side surface of the tunable lens 90 and the object-side surface of the first lens group on the optical axis. This is the distance between the image-side surface of the tunable mirror and the image-side surface of the second lens group on the optical axis. For example, It can take values ​​of 0.94, 0.96, 0.98, 1.0, etc. This application uses... This ensures that the tunable lens 90 is located at the position most sensitive to changes in optical power in the entire optical imaging system, which is beneficial for making full use of the optical power of the tunable lens 90, thereby increasing the focusing distance range of the tunable lens 90.

[0042] Furthermore, the optical imaging system satisfies the following relationship: ,in, To adjust the optical power of the mirror, This is the effective focal length of the optical imaging system. For example, You can choose 4.0. 4.1 Etc. In this application, by using This ensures that the tunable lens 90 can be adjusted within a suitable range of optical power variation. When the optical imaging system of this application is installed in an endoscope, the farthest focusing range of the endoscope can cover the entire abdominal cavity, and the closest focusing range can clearly see fine tissues and blood vessels.

[0043] Furthermore, the optical imaging system of this application also includes an aperture stop 80, which is located between the first lens group and the tunable lens 90. The optical imaging system satisfies the following relationship: ,in, The distance between aperture 80 and the side of the first lens group closest to the object on the optical axis. The distance between the object-side surfaces of the aperture stop 80 and the tunable lens 90 on the optical axis. For example, Possible values ​​include 29.2, 29.4, 29.6, and 29.8. This application utilizes... This ensures that the field of view, image height, and entrance pupil diameter of the optical imaging system do not change significantly during focusing, which is beneficial for achieving full depth imaging through image fusion using algorithms in the later stages. Of course, in other applications of this application, the aperture stop 80 can also be positioned between any two adjacent lenses. Any other variations based on the concept of this application are within the scope of protection of this application. By positioning the aperture stop 80 close to the tunable lens 90 in this application, the breathing effect during autofocus (i.e., the phenomenon of the lens field of view changing with focal length during focusing) can be reduced. Compared with traditional focusing systems, the optical imaging system in this application has a more continuous and comfortable focusing effect.

[0044] Furthermore, the second lens group comprises a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70 arranged sequentially from the object side to the image side. The fourth lens 40 has convex object-side and image-side surfaces; the fifth lens 50 and the sixth lens 60 are cemented together to form a cemented doublet, with both the object-side and image-side surfaces of the fifth lens 50 being concave; the object-side and image-side surfaces of the sixth lens 60 are convex; and both the object-side and image-side surfaces of the seventh lens 70 are convex. In this application, the fifth lens 50 is a high-refractive-index, low-Abbe-number glass negative lens, and the sixth lens 60 is a low-refractive-index, high-Abbe-number glass positive lens. By setting the fifth lens 50 and the sixth lens 60 as a cemented doublet, in addition to reducing spherical aberration and coma and improving the imaging quality of the optical imaging system, it can also effectively compensate for chromatic aberration in the optical imaging system. Meanwhile, as an integrated component, the doublet lens can reduce the sensitivity to eccentricity and tilt during assembly. In addition, the fifth lens 50 is a biconcave lens with both the object side and the image side edge designed as a plateau. When the fourth lens 40 and the seventh lens 70 rely on the spacer to support the plateau surface of the fifth lens 50, the sensitivity of the fourth lens 40 and the fifth lens 50 to assembly tilt can be effectively reduced.

[0045] Furthermore, the optical imaging system in this application satisfies the following relationship: ,in, Let be the radius of curvature of the object-side surface of the fifth lens 50. The radius of curvature of the image-side surface of the sixth lens 60. This application achieves this by using... This not only enables the fourth lens 40 to better correct the transverse chromatic aberration of the entire optical imaging system, but also effectively controls the process parameters of the fifth lens 50 and the sixth lens 60 to meet processing requirements, while also controlling the trend of edge rays in the optical imaging system.

[0046] Furthermore, the optical imaging system in this application satisfies the following relationship: ,in, The focal length of the fifth lens is 50. The focal length of the sixth lens is 60. This is the combined focal length of the fifth lens 50 and the sixth lens 60. For example, Possible values ​​include 0.59, 0.61, 0.62, 0.63, and 0.64. This application utilizes... It can control the contribution of the fifth lens 50 and the sixth lens 60 to aberrations, and thus balance the aberrations generated by other optical elements, so that the aberrations of the optical imaging system are kept within a reasonable range.

[0047] Furthermore, the optical imaging system in this application satisfies the following relationship: ,in, The focal length of the seventh lens is 70. This is the effective focal length of the optical imaging system. For example, It can take values ​​of 3.45, 3.50, 3.55, etc. This application enables... This facilitates the control of the principal ray angle of the light emitted from the optical imaging system and matches it with the principal ray angle of the image sensor, thus avoiding vignetting or color crosstalk at the edges of the final image.

[0048] Furthermore, the optical imaging system of this application also includes a protective glass plate 110, which is located on the object side of the first lens group and can protect the first lens group. Optionally, the protective glass plate 110 is optical protective glass, which has a simple structure and is easy to manufacture. Of course, the protective glass plate 110 in this application can be replaced with an optical plastic sheet, etc. Any other protective structure within the concept of this application is within the scope of protection of this application. In addition, in order to protect the tunable lens 90, a protective glass sheet or a protective plastic sheet, etc., can also be provided on the image side of the tunable lens 90.

[0049] The optical imaging system of this application will be described in detail below with specific examples.

[0050] Example 1

[0051] See Figures 1 to 11 As shown, according to an embodiment of this application, an optical imaging system is provided, which includes a protective glass plate 110, a first lens 10, a second lens 20, a third lens 30, an aperture 80, a tunable lens 90 (the image side of the tunable lens 90 is provided with protective glass), a fourth lens 40, a fifth lens 50, a sixth lens 60, and a seventh lens 70 arranged sequentially from the object side to the image side.

[0052] In this embodiment, the object-side and image-side surfaces of the first lens 10, second lens 20, third lens 30, fourth lens 40, fifth lens 50, sixth lens 60, and seventh lens 70 are all spherical, resulting in a simple structure and low manufacturing cost. Specifically, the object-side surface of the first lens 10 is convex, and the image-side surface is concave; the object-side surface of the second lens 20 is convex, and the image-side surface is concave; both the object-side and image-side surfaces of the third lens 30 are convex; both the object-side and image-side surfaces of the fourth lens 40 are convex; the fifth lens 50 and the sixth lens 60 are cemented doublet lenses, with both the object-side and image-side surfaces of the fifth lens 50 being concave; the object-side surface of the sixth lens 60 being concave, and the image-side surface being convex; and both the object-side and image-side surfaces of the seventh lens 70 are convex. All the lenses—first lens 10, second lens 20, third lens 30, fourth lens 40, fifth lens 50, sixth lens 60, and seventh lens 70—are glass lenses.

[0053] Table 1 is a characteristic table of the optical imaging system in this embodiment, where the units for radius and thickness are mm.

[0054] Table 1:

[0055]

[0056] The tunable lens 90 of the optical imaging system disclosed in this embodiment can achieve high-quality, clear focusing within an object distance range of 10mm-150mm, and the MTF (optical modulation function) of imaging at object distances of 10mm-150mm approaches the diffraction limit. Table 2 reflects the optical power values ​​provided by the tunable lens 90 for clear imaging at different object distances.

[0057] Table 2:

[0058]

[0059] in, Figures 3 to 8 The optical modulation functions of the optical imaging system of this embodiment at object distances of 150mm, 110mm, 70mm, 40mm, 20mm, and 10mm are shown, where the vertical axis represents contrast and the horizontal axis represents spatial frequency (line pairs / mm). According to Figures 3 to 8 It can be seen that when the optical imaging system of this embodiment is adjusted to different object distances, the curves under different fields of view all approach the diffraction limit. Figure 9 The horizontal axis represents the distortion rate ( / %), and the vertical axis represents the field of view. Figure 10 The horizontal axis represents the distance from the image plane in mm, and the vertical axis represents the field of view in degrees. Figure 11 The horizontal axis represents the field of view angle in degrees, and the vertical axis represents the relative illumination value in percentage. According to... Figures 3 to 11As can be seen, the optical imaging system given in Example 1 can achieve good imaging quality.

[0060] Based on the above embodiments, it can be seen that the photoelectric imaging system applied to endoscopes of this application utilizes a tunable lens 90 to achieve high-resolution imaging with automatic focusing over a wide observation depth range. Compared to fixed-focus electronic endoscope systems, this application can balance a wide observation depth with high imaging quality, continuously and accurately capturing clear images of internal organs and tissues, significantly improving the operational efficiency of doctors in the diagnosis and treatment process, and making the observation and analysis of complex cases more convenient and reliable. Compared to existing traction-type mechanical focusing solutions, this application uses voltage-driven direct adjustment of the tunable lens 90 to achieve focusing, eliminating the need for complex mechanisms, simplifying the structure and assembly, enabling miniaturization and automation, and providing continuous and accurate focusing distance; the optical imaging system is unaffected by magnetic fields and gravity, and has the potential to support high-temperature and high-pressure sterilization. Compared to existing focusing solutions using zoom lenses, this application has a focusing observation range covering the entire human abdominal cavity from 10mm to 150mm, and maintains high imaging quality close to the diffraction limit throughout the entire focusing range, possessing the potential for full 4K imaging.

[0061] Existing adjustable curvature lenses are mostly liquid lenses, based on the principle of electrowetting. These liquid lenses require a large drive, making them difficult to apply in practical endoscope objectives. In contrast, the adjustable lens in this solution is a piezoelectric adjustable lens, based on the piezoelectric principle. Compared to liquid lenses, piezoelectric adjustable lenses are smaller, more integrated, and have a faster zoom speed. They can be directly integrated into the front end of the objective lens and can be installed within the limited space of the endoscope.

[0062] On the other hand, this application also discloses an endoscope that includes the aforementioned optical imaging system. Therefore, this endoscope possesses all the technical effects of the aforementioned optical imaging system. Since the effects of the optical imaging system have already been described in detail above, they will not be repeated here.

[0063] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0064] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An optical imaging system, characterized in that, It consists of a first lens group, an adjustable lens (90), and a second lens group arranged sequentially from the object side to the image side, wherein, The first lens group consists of a first lens (10), a second lens (20), and a third lens (30) arranged sequentially from the object side to the image side; the object side of the first lens (10) is convex and the image side is concave; the object side of the second lens (20) is convex and the image side is concave; both the image side and the object side of the third lens (30) are convex; the optical power of the first lens (10) and the second lens (20) are negative. The second lens group consists of a fourth lens (40), a fifth lens (50), a sixth lens (60), and a seventh lens (70) arranged sequentially from the object side to the image side; the object side and the image side of the fourth lens (40) are both convex; the fifth lens (50) and the sixth lens (60) are cemented together to form a cemented doublet lens, the object side and the image side of the fifth lens (50) are both concave; the object side and the image side of the sixth lens (60) are both convex; the object side and the image side of the seventh lens (70) are both convex. The tunable lens (90) is equipped with a control board (100) for applying different driving voltages to the tunable lens (90) to adjust the radius of curvature of the tunable lens (90); The optical imaging system satisfies the following relationship: ,in, The distance between the object-side surface of the tunable lens (90) and the object-side surface of the first lens group on the optical axis. The distance between the image-side surface of the tunable lens (90) and the image-side surface of the second lens group on the optical axis; The optical imaging system satisfies the following relationship: ,in, The optical power of the tunable lens (90) is... The effective focal length of the optical imaging system is given.

2. The optical imaging system according to claim 1, characterized in that, The optical imaging system further includes an aperture stop (80), which is located between the first lens group and the tunable lens (90). The optical imaging system satisfies the following relationship: ,in, The distance on the optical axis between the aperture stop (80) and the side of the first lens group closest to the object side is... The distance between the object side of the aperture (80) and the tunable lens (90) on the optical axis.

3. The optical imaging system according to claim 1, characterized in that, The optical imaging system satisfies the following relationship: ,in, The combined focal length of the first lens (10) and the second lens (20) is... The effective focal length of the optical imaging system is given.

4. The optical imaging system according to claim 1, characterized in that, The optical imaging system satisfies the following relationship: ,in, The focal length of the third lens (30) is... The effective focal length of the optical imaging system is given.

5. The optical imaging system according to any one of claims 1 to 4, characterized in that, The optical imaging system satisfies the following relationship: ,in, The radius of curvature of the object-side surface of the fifth lens (50) is given. The radius of curvature of the image side surface of the sixth lens (60).

6. The optical imaging system according to any one of claims 1 to 5, characterized in that, The optical imaging system satisfies the following relationship: ,in, The focal length of the fifth lens (50) is... The focal length of the sixth lens (60) is... The combined focal length of the fifth lens (50) and the sixth lens (60).

7. The optical imaging system according to any one of claims 1 to 6, characterized in that, The optical imaging system satisfies the following relationship: ,in, The focal length of the seventh lens (70) is... The effective focal length of the optical imaging system is given.

8. An endoscope, characterized in that, The endoscope includes the optical imaging system according to any one of claims 1 to 7.

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