Liquid Lens-Based Autofocus Optical Imaging System

Abstract

This invention discloses an autofocus optical imaging system based on a liquid lens, comprising a first lens group, an aperture, a second lens group, a cover glass, and a CMOS photosensitive surface arranged sequentially from left to right along the incident light direction. The first lens group includes lenses one, two, and three; lenses one and two have positive refractive power, are convex on the object side, and concave on the image side; lens three has negative refractive power, is concave on the object side, and concave on the image side. The second lens group includes lenses four, five, six, liquid, seven, and eight; lens four has positive refractive power, is convex on the object side, and convex on the image side; lens five has negative refractive power, is concave on the object side, and convex on the image side; lens six has positive refractive power, is convex on the object side, and convex on the image side; lens seven has positive refractive power, is convex on the object side, and convex on the image side; and lens eight has negative refractive power, is concave on the object side, and convex on the image side. The liquid lens includes a first transparent surface layer, a first liquid region, an elastic film layer, a second liquid region, and a second transparent surface layer. It has a wide operating band, a large field of view, a large target surface, and a small F-number. It can quickly autofocus, is noiseless, has a compact structure, and has stable imaging quality.

Description

Technical Field

[0001] This invention relates to the field of optical system technology, and more specifically, to an autofocus optical imaging system based on a liquid lens. Background Technology

[0002] Currently, camera autofocus primarily relies on a motor-driven lens to adjust the optical distance between the lens and the camera sensor, compensating for focus shifts caused by changes in working distance or ambient temperature. However, driving lenses and lens groups along the optical axis with a motor complicates the camera's structure and assembly, increasing its size and weight, and making it inconvenient to use. Furthermore, focusing via a motor requires a considerable amount of time to control the motor, preventing the camera from effectively meeting the demands of applications with high real-time performance requirements.

[0003] In recent years, a novel optical element based on biomimetic concepts, the "liquid lens," has been developed. Unlike motor-driven lens or lens assembly movement for focusing, the liquid lens only needs to change its shape or refractive index through electronic control, without moving any components in the camera system. Optical imaging lenses with liquid lenses can achieve autonomous focusing, making significant contributions to the miniaturization of camera systems and rapid target acquisition.

[0004] However, the image quality of optical imaging lenses with liquid lenses that have appeared on the market in the past two years has been poor, resulting in limitations in their application areas. Therefore, there is an urgent need to optimize the optical technology of existing optical imaging lenses with liquid lenses and design optical imaging lenses based on liquid lenses that combine small size and large relative aperture to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of poor imaging quality and limited application fields of existing optical imaging lenses with liquid lenses. It provides an autofocus optical imaging system based on liquid lenses. This system has a wide operating band, a large field of view, a large target surface, and a small F number. It can achieve fast autofocus from 0.5m to infinity, and is noiseless, compact in structure, and has more stable imaging quality.

[0006] To achieve the above objectives, the present invention provides an autofocus optical imaging system based on a liquid lens. This optical imaging system includes, from left to right along the light incident direction, a first lens group with negative optical power, an aperture stop, a second lens group with positive optical power, a cover glass, and a CMOS photosensitive surface. The first lens group and the second lens group constitute a reverse telephoto structure. Furthermore, the first lens group is used to adjust the object-side light, and the second lens group is used to control the large relative aperture.

[0007] The first lens group includes a first lens, a second lens, and a third lens sequentially from the object side to the image side along the optical axis. The first and second lenses have positive refractive power and the object side is a convex spherical surface, while the image side is a concave spherical surface. The third lens has negative refractive power and the object side is a concave spherical surface, while the image side is a concave spherical surface.

[0008] The second lens group, from left to right, includes a cemented lens formed by cementing the fourth and fifth lenses, a sixth lens, a liquid lens, a seventh lens, and an eighth lens. The fourth lens has positive refractive power and its object side and image side are both convex spherical. The fifth lens has negative refractive power and its object side and image side are both concave spherical. The sixth lens has positive refractive power and its object side and image side are both convex spherical. The seventh lens has positive refractive power and its object side and image side are both convex spherical. The eighth lens has negative refractive power and its object side and image side are both concave spherical. The liquid lens, along the optical axis from the object side to the image side, includes a first transparent layer, a first liquid region, an elastic film layer, a second liquid region, and a second transparent layer.

[0009] Preferably, the focal length of the optical imaging system is set according to formulas (1) and (2). f ,

[0010] (1)

[0011] (2)

[0012] in, f 第一透镜组 The combined focal length of the first to the third lens. f 第二透镜组 This is the combined focal length from the cemented lens to the eighth lens.

[0013] Preferably, the liquid lens is configured to be able to:

[0014] When the object distance is 500mm, the radius of curvature of the elastic membrane is adjusted to -15.5mm, the edge thickness of the first liquid zone is adjusted to 0.633mm, and the edge thickness of the second liquid zone is adjusted to 2.211mm.

[0015] When the object distance is 1000mm, the radius of curvature of the elastic membrane is adjusted to -32.8mm, the edge thickness of the first liquid zone is adjusted to 1.249mm, and the edge thickness of the second liquid zone is adjusted to 1.594mm.

[0016] When the object distance is 5000mm, the elastic membrane layer is adjusted to be planar, the edge thickness of the first liquid zone is adjusted to 1.79mm, and the edge thickness of the second liquid zone is adjusted to 1.053mm.

[0017] When the object distance is 10000mm, the radius of curvature of the elastic membrane is adjusted to 280mm, the edge thickness of the first liquid zone is adjusted to 1.854mm, and the edge thickness of the second liquid zone is adjusted to 0.99mm.

[0018] When the object distance is 25000mm, the radius of curvature of the elastic membrane is adjusted to 143mm, the edge thickness of the first liquid zone is adjusted to 1.915mm, and the edge thickness of the second liquid zone is adjusted to 0.928mm.

[0019] When the object distance is infinite, the radius of curvature of the elastic membrane is adjusted to 119 mm, the edge thickness of the first liquid zone is adjusted to 1.941 mm, and the edge thickness of the second liquid zone is adjusted to 0.903 mm.

[0020] Preferably, in the first lens group,

[0021] The radius of curvature of the object side of the first lens is 15~17.5mm, and the radius of curvature of the image side is 27.5~30.5mm;

[0022] The radius of curvature of the object side of the second lens is 13.5~15.5mm, and the radius of curvature of the image side is 46.8~50.5mm;

[0023] The radius of curvature of the object side of the third lens is -30.5~32.5mm, and the radius of curvature of the image side is 11.8~13.5mm.

[0024] Preferably, in the first lens group, the air gap between the first lens and the second lens is 0.2 mm, and the air gap between the second lens and the third lens is 0.98 mm.

[0025] Preferably, in the cemented lens, the image-side surface of the fourth lens is cemented to the object-side surface of the fifth lens; wherein,

[0026] The radius of curvature of the object side of the fourth lens is 15.2~17.8mm, and the radius of curvature of the image side is -16.5~-14.5mm;

[0027] The radius of curvature of the object side of the fifth lens is -14.5 to -16.5 mm, and the radius of curvature of the image side is -38.5 to -35.5 mm.

[0028] Preferably, in the second lens group,

[0029] The radius of curvature of the object side of the sixth lens is 41.5~43.5mm, and the radius of curvature of the image side is -79.5~-77.5mm;

[0030] The radius of curvature of the object side of the seventh lens is 85.2~87.5mm, and the radius of curvature of the image side is -59.8~-57.5mm;

[0031] The radius of curvature of the object side of the eighth lens is -9.5 to -8.2 mm, and the radius of curvature of the image side is -32.5 to -29.5 mm.

[0032] Preferably, in the second lens group, the air gap between the cemented lens and the sixth lens is 1.02 mm, the air gap between the sixth lens and the liquid lens is 0.25 mm, the air gap between the liquid lens and the seventh lens is 0.21 mm, and the air gap between the seventh lens and the eighth lens is 2.55 mm.

[0033] Preferably, the aperture stop is located between the first lens group and the second lens group, and the air gap along the optical axis to the first lens group is 2.25 mm, and the air gap along the optical axis to the second lens group is 0 mm.

[0034] Preferably, the back focal length of the second lens group is 2.195mm, the distance from the second lens group to the cover glass is 1.012mm, the thickness of the cover glass is 0.55mm, and the air gap between the CMOS photosensitive surface and the cover glass is 0.75mm.

[0035] Through the above technical solution, the first lens group is used to adjust the object-side light so that the object-side field of view meets the field of view requirements of the optical system; the second lens group is responsible for large relative aperture control. This optical design, through the rational allocation of optical components, solves the installation limitations of short focal length lenses in compact spaces and is an important solution for large field-of-view optical systems. Simultaneously, the optical imaging system of this invention, by integrating liquid lenses, can quickly adjust the focal length to adapt to objects with different working distances and depth-of-field requirements, significantly improving imaging accuracy and speed. Furthermore, through the design of the optical materials, surface curvature, thickness, and air gaps between the lenses from the first to the eighth lens, the light transmission path and imaging quality are optimized, not only meeting the application scenario and imaging clarity requirements but also achieving fast autofocus. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the autofocus optical imaging system based on a liquid lens provided in this invention;

[0037] Figure 2 The diagram shows the dot matrix of the autofocus optical imaging system based on a liquid lens provided by this invention at an object distance of 500mm.

[0038] Figure 3 This is a dot diagram of the autofocus optical imaging system based on a liquid lens provided by the present invention at an object distance of 1000mm.

[0039] Figure 4 This is a dot diagram of the autofocus optical imaging system based on a liquid lens provided by the present invention at an object distance of 5000mm.

[0040] Figure 5 This is a dot diagram of the autofocus optical imaging system based on a liquid lens provided by the present invention at an object distance of 10000mm.

[0041] Figure 6 This is a dot diagram of the autofocus optical imaging system based on a liquid lens provided by the present invention at an object distance of 25000mm.

[0042] Figure 7 This is a dot diagram of the autofocus optical imaging system based on a liquid lens provided by the present invention when the object distance is infinite.

[0043] Figure 8 The distortion curve of the autofocus optical imaging system based on liquid lens provided by this invention is shown when the object distance is 500mm.

[0044] Figure 9 The distortion curve of the autofocus optical imaging system based on liquid lens provided by this invention is shown when the object distance is 1000mm.

[0045] Figure 10 The distortion curve of the autofocus optical imaging system based on liquid lens provided by this invention is shown when the object distance is 5000mm.

[0046] Figure 11 The distortion curve of the autofocus optical imaging system based on liquid lens provided by this invention is shown when the object distance is 10000mm.

[0047] Figure 12 The distortion curve of the autofocus optical imaging system based on liquid lens provided by this invention is shown when the object distance is 25000mm.

[0048] Figure 13 The distortion curve of the autofocus optical imaging system based on a liquid lens provided by this invention is shown when the object distance is infinite.

[0049] Explanation of reference numerals in the attached figures

[0050] 1-First lens group, 2-Aperture, 3-Second lens group, 4-Liquid lens, 11-First lens, 12-Second lens, 13-Third lens, 34-Fourth lens, 35-Fifth lens, 36-Sixth lens, 37-Seventh lens, 38-Eighth lens, 9-Cover glass, 10-CMOS photosensitive surface. Detailed Implementation

[0051] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0052] In this invention, unless otherwise stated, directional terms such as "left" and "right" included in the terminology represent only the orientation of the term in its normal use or are common terms understood by those skilled in the art, and should not be regarded as a limitation on the term.

[0053] See Figure 1 This invention provides an autofocus optical imaging system based on a liquid lens. The system includes a first lens group 1 with negative optical power, an aperture 2, a second lens group 3 with positive optical power, a cover glass 9, and a CMOS sensor 10, arranged sequentially from left to right along the light incident direction. The first lens group 1 and the second lens group 3 form a reverse telephoto structure. The first lens group 1 is used to adjust the object-side light, and the second lens group 3 is used to control the large relative aperture.

[0054] The first lens group 1 includes a first lens 11, a second lens 12, and a third lens 13 sequentially from the object side to the image side along the optical axis. The first lens 11 and the second lens 12 have positive refractive power and the object side is a convex spherical surface and the image side is a concave spherical surface; the third lens 13 has negative refractive power and the object side is a concave spherical surface and the image side is a concave spherical surface.

[0055] The second lens group 3, from left to right, includes a cemented lens formed by cementing a fourth lens 34 and a fifth lens 35, a sixth lens 36, a liquid lens 4, a seventh lens 37, and an eighth lens 38. The fourth lens 34 has positive refractive power and its object side and image side are both convex spherical. The fifth lens 35 has negative refractive power and its object side and image side are both concave spherical. The sixth lens 36 has positive refractive power and its object side and image side are both convex spherical. The seventh lens 37 has positive refractive power and its object side and image side are both convex spherical. The eighth lens 38 has negative refractive power and its object side and image side are both concave spherical. The liquid lens 4, along the optical axis from the object side to the image side, includes a first transparent layer, a first liquid region, an elastic film layer, a second liquid region, and a second transparent layer.

[0056] In this embodiment, the first lens group of the optical imaging system is used to adjust the object-side light so that the object-side field of view meets the field of view requirements of the optical system; the second lens group is responsible for large relative aperture control. This optical design solves the installation limitations of short focal length lenses in a compact space through the reasonable allocation of optical components, and is an important solution for large field of view optical systems.

[0057] In this embodiment, in order to ensure that the optical power distribution of the first lens group and the second lens group of the optical imaging system not only meets the needs of a large field of view optical system, but also facilitates the realization of small F-number large target surface imaging, preferably, the focal length of the optical imaging system should also be set according to formulas (1) and (2). f ,

[0058] (1)

[0059] (2)

[0060] in, f 第一透镜组 The combined focal length of the first lens 11 to the third lens 13 f 第二透镜组 This is the combined focal length from the cemented lens to the eighth lens 38.

[0061] In this embodiment, in order to enable rapid focal length adjustment via the integrated liquid lens to adapt to objects with different working distances and depth-of-field requirements, and to significantly improve imaging accuracy and speed, the liquid lens 4 is preferably configured to:

[0062] When the object distance is 500mm, the radius of curvature of the elastic membrane is adjusted to -15.5mm, the edge thickness of the first liquid zone is adjusted to 0.633mm, and the edge thickness of the second liquid zone is adjusted to 2.211mm.

[0063] When the object distance is 1000mm, the radius of curvature of the elastic membrane is adjusted to -32.8mm, the edge thickness of the first liquid zone is adjusted to 1.249mm, and the edge thickness of the second liquid zone is adjusted to 1.594mm.

[0064] When the object distance is 5000mm, the elastic membrane layer is adjusted to be planar, the edge thickness of the first liquid zone is adjusted to 1.79mm, and the edge thickness of the second liquid zone is adjusted to 1.053mm.

[0065] When the object distance is 10000mm, the radius of curvature of the elastic membrane is adjusted to 280mm, the edge thickness of the first liquid zone is adjusted to 1.854mm, and the edge thickness of the second liquid zone is adjusted to 0.99mm.

[0066] When the object distance is 25000mm, the radius of curvature of the elastic membrane is adjusted to 143mm, the edge thickness of the first liquid zone is adjusted to 1.915mm, and the edge thickness of the second liquid zone is adjusted to 0.928mm.

[0067] When the object distance is infinite, the radius of curvature of the elastic membrane is adjusted to 119 mm, the edge thickness of the first liquid zone is adjusted to 1.941 mm, and the edge thickness of the second liquid zone is adjusted to 0.903 mm.

[0068] In this embodiment, in order to optimize the light transmission path and image quality through the design of the optical materials, surface curvature, thickness, and air gaps between the first to eighth lenses, while simultaneously meeting the requirements of the application scenario, image sharpness, and fast autofocus, it is preferable that in the first lens group 1,

[0069] The radius of curvature of the object side of the first lens 11 is 15~17.5mm, and the radius of curvature of the image side is 27.5~30.5mm;

[0070] The radius of curvature of the object side of the second lens 12 is 13.5~15.5mm, and the radius of curvature of the image side is 46.8~50.5mm;

[0071] The radius of curvature of the object side of the third lens 13 is -30.5~32.5mm, and the radius of curvature of the image side is 11.8~13.5mm.

[0072] Furthermore, preferably in the first lens group 1, the air gap between the first lens 11 and the second lens 12 is 0.2 mm, and the air gap between the second lens 12 and the third lens 13 is 0.98 mm.

[0073] Similarly, preferably in a cemented lens, the image-side surface of the fourth lens 34 is cemented to the object-side surface of the fifth lens 35; wherein,

[0074] The radius of curvature of the object side of the fourth lens 34 is 15.2~17.8mm, and the radius of curvature of the image side is -16.5~-14.5mm;

[0075] The fifth lens 35 has an object side radius of curvature of -14.5 to -16.5 mm and an image side radius of curvature of -38.5 to -35.5 mm.

[0076] Furthermore, preferably in the second lens group 3,

[0077] The radius of curvature of the object side of the sixth lens 36 is 41.5~43.5mm, and the radius of curvature of the image side is -79.5~-77.5mm;

[0078] The radius of curvature of the object side of the seventh lens 37 is 85.2~87.5mm, and the radius of curvature of the image side is -59.8~-57.5mm;

[0079] The radius of curvature of the object side of the eighth lens 38 is -9.5 to -8.2 mm, and the radius of curvature of the image side is -32.5 to -29.5 mm.

[0080] Furthermore, in the second lens group 3, the air gap between the cemented lens and the sixth lens 36 is 1.02 mm, the air gap between the sixth lens 36 and the liquid lens 4 is 0.25 mm, the air gap between the liquid lens 4 and the seventh lens 37 is 0.21 mm, and the air gap between the seventh lens 37 and the eighth lens 38 is 2.55 mm.

[0081] In this embodiment, the aperture stop 2 is preferably located between the first lens group 1 and the second lens group 3, and the air gap along the optical axis to the first lens group 1 is 2.25 mm, and the air gap along the optical axis to the second lens group 3 is 0 mm.

[0082] In this embodiment, the back focal length of the second lens group 3 is preferably 2.195 mm, the distance between the second lens group 3 and the cover glass 9 is 1.012 mm, the thickness of the cover glass 9 is 0.55 mm, and the air gap between the CMOS photosensitive surface 10 and the cover glass 9 is 0.75 mm.

[0083] The following is a specific embodiment to illustrate the autofocus optical imaging system based on liquid lenses provided by the present invention:

[0084] First, in this embodiment, the object-side (or image-side) of the lens refers to a specific area on the lens surface through which imaging light penetrates. The determination of the surface shape of the lens follows conventional methods in this field, namely, based on the sign of the radius of curvature. The radius of curvature is widely used in optical design software, such as ZEMAX and CODE V, and can be found in the lens data tables of the software. Specifically, for the object-side, when the radius of curvature is positive, the object-side is determined to be a convex spherical surface; conversely, it is determined to be a concave spherical surface. Correspondingly, for the image-side, when the radius of curvature is positive, the object-side is determined to be a concave spherical surface; conversely, it is determined to be a convex spherical surface.

[0085] according to Figure 1An autofocus optical imaging system with a large field of view, large target area, small F-number, and liquid lens is designed. The negative lens group is in front, and the positive lens group is behind, forming a reverse telephoto structure, which is beneficial for realizing a low-light night vision camera with a large field of view, large relative aperture, and large target area. The liquid lens, along the optical axis from the object side to the image side, includes: a first transparent layer, a first liquid region, an elastic film layer, a second liquid region, and a second transparent layer. The liquid lens can be placed in two positions: at the front of the optical imaging system or embedded in the optical system. However, considering that if the camera is used in an airborne integrated helmet-mounted display system and embedded in the flight helmet, the camera must be compact and miniaturized. Placing it at the front of the optical imaging system would increase the camera's size; therefore, the liquid lens is embedded in the middle of the system. Furthermore, to match the light-transmitting aperture of the liquid lens and minimize the introduction of aberrations, the liquid lens is embedded between the sixth and seventh lenses in the rear group, which have a small and relatively gradual change in light aperture. Simultaneously, the working distance for the liquid lens with a diopter of 0 dpt was set to 5000 mm. Multiple structures with different object distances were set using the THIC multi-structure operand: 500 mm, 1000 mm, 5000 mm, 10000 mm, 25000 mm, and infinity (6 structures). The diopter of the liquid lens was controlled by controlling the focal length of the liquid lens through the CRVT multi-structure operand. Since the liquid lens can only achieve focusing and cannot be used to correct aberrations, it is necessary to minimize the introduction of other aberrations when embedding the liquid lens. However, it is impossible to completely eliminate aberrations. Aberration correction is achieved by appropriately adjusting the optical materials, surface curvature, thickness, and lens spacing of the optical imaging system with the embedded liquid lens, thus realizing clear imaging.

[0086] This embodiment requires the following optical performance indicators to be met:

[0087] 1. Operating wavelength: 585nm~950nm;

[0088] 2. Field of view: not less than 40° × 32°;

[0089] 3. Relative aperture ratio 1:1.25;

[0090] 4. Image sensor: Compatible with CMOS image sensor with resolution of 1280×1024 and pixel size of 9.7µm;

[0091] 5. Resolution: ≤1.32mrad@ambient illuminance 10 -3 Lux;

[0092] 6. Operating temperature: -45℃~65℃;

[0093] 7. Autofocus range: 0.5m to infinity.

[0094] In this embodiment, the optical element parameters are shown in Table 1 below:

[0095] Table 1

[0096]

[0097] The values ​​of D1 and D2 for the liquid lens are shown in Table 2 (Liquid Lens Parameters for Different Object Distances):

[0098] Table 2

[0099]

[0100] For a detailed dot plot of different working distances (500mm, 1000mm, 5000mm, 10000mm, 25000mm and infinity) in this embodiment, please refer to [link / reference]. Figures 2-7 As shown in the figure, the RMS radius of the 0.7 field-of-view dot matrix is ​​9.6μm, which is smaller than the pixel size of the selected CMOS chip (9.7μm), indicating that the optical imaging system has high imaging clarity.

[0101] For details of the field curvature and distortion curves at different working distances (500mm, 1000mm, 5000mm, 10000mm, 25000mm and infinity) in this embodiment, please refer to [link to relevant documentation]. Figures 8-13 As shown in the figure, the distortion of the full-field optical imaging system is less than 2%, indicating that the optical imaging system has low distortion. At the same time, the field curvature of the full-field optical imaging system is less than 0.12mm. The system has a relatively small focal length and a depth of focus that is much greater than the field curvature, which will not affect the clarity of the full-field imaging.

[0102] In summary, the optical imaging system provided by this invention achieves a wide operating wavelength of 585nm-950nm, a large field of view of 40°×32°, a small F-number of 1.25, a large target surface with a resolution of 1280×1024 and a pixel size of 9.7μm, and automatic focusing from 0.5m to infinity. From the point plots and field curvature and distortion curves at object distances of 500mm, 1000mm, 5000mm, 10000mm, 25000mm, and infinity, it can be seen that this optical imaging system can achieve rapid automatic focusing from 500mm to infinity, with a time of milliseconds. The overall optical imaging system has minimal noise, a compact structure, and more stable imaging quality compared to traditional integrated moving focusing lenses, making it a promising candidate for applications in military, surveillance, and other fields.

[0103] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An autofocus optical imaging system based on a liquid lens, characterized in that, The optical imaging system includes a first lens group (1) with negative optical power, an aperture stop (2), a second lens group (3) with positive optical power, a cover glass (9), and a CMOS photosensitive surface (10) arranged sequentially from left to right along the incident light direction. The first lens group (1) and the second lens group (3) constitute a reverse telephoto structure. The first lens group (1) is used to adjust the object-side light, and the second lens group (3) is used to control the large relative aperture. The first lens group (1) includes a first lens (11), a second lens (12) and a third lens (13) along the optical axis from the object side to the image side. The first lens (11) and the second lens (12) have positive refractive power and the object side is a convex spherical surface and the image side is a concave spherical surface. The third lens (13) has negative refractive power and the object side is a concave spherical surface and the image side is a concave spherical surface. The second lens group (3) includes, from left to right, a cemented lens formed by cementing a fourth lens (34) and a fifth lens (35), a sixth lens (36), a liquid lens (4), a seventh lens (37), and an eighth lens (38). The fourth lens (34) has positive refractive power and the object side and the image side are convex spherical. The fifth lens (35) has negative refractive power and the object side and the image side are concave spherical. The sixth lens (36) has positive refractive power and the object side and the image side are convex spherical. The seventh lens (37) has positive refractive power and the object side and the image side are convex spherical. The eighth lens (38) has negative refractive power and the object side and the image side are concave spherical. The liquid lens (4) includes, along the optical axis from the object side to the image side, a first transparent layer, a first liquid region, an elastic film layer, a second liquid region, and a second transparent layer.

2. The autofocus optical imaging system based on a liquid lens according to claim 1, characterized in that, The focal length of the optical imaging system is set according to formulas (1) and (2). f , ，（1） ，（2） in, f 第一透镜组 The combined focal length of the first lens (11) to the third lens (13) f 第二透镜组 The combined focal length from the cemented lens to the eighth lens (38).

3. The autofocus optical imaging system based on a liquid lens according to claim 1, characterized in that, The liquid lens (4) is configured to be able to: When the object distance is 500mm, the radius of curvature of the elastic membrane layer is adjusted to -15.5mm, the edge thickness of the first liquid region is adjusted to 0.633mm, and the edge thickness of the second liquid region is adjusted to 2.211mm. When the object distance is 1000mm, the radius of curvature of the elastic membrane layer is adjusted to -32.8mm, the edge thickness of the first liquid region is adjusted to 1.249mm, and the edge thickness of the second liquid region is adjusted to 1.594mm. When the object distance is 5000mm, the elastic membrane layer is adjusted to be planar, the edge thickness of the first liquid region is adjusted to 1.79mm, and the edge thickness of the second liquid region is adjusted to 1.053mm. When the object distance is 10000mm, the radius of curvature of the elastic membrane layer is adjusted to 280mm, the edge thickness of the first liquid region is adjusted to 1.854mm, and the edge thickness of the second liquid region is adjusted to 0.99mm. When the object distance is 25000mm, the radius of curvature of the elastic membrane layer is adjusted to 143mm, the edge thickness of the first liquid region is adjusted to 1.915mm, and the edge thickness of the second liquid region is adjusted to 0.928mm. When the object distance is infinite, the radius of curvature of the elastic membrane is adjusted to 119 mm, the edge thickness of the first liquid region is adjusted to 1.941 mm, and the edge thickness of the second liquid region is adjusted to 0.903 mm.

4. The autofocus optical imaging system based on a liquid lens according to claim 1, characterized in that, In the first lens group (1), The first lens (11) has a radius of curvature of 15~17.5mm on the object side and a radius of curvature of 27.5~30.5mm on the image side; The second lens (12) has a radius of curvature of 13.5~15.5 mm on the object side and a radius of curvature of 46.8~50.5 mm on the image side; The third lens (13) has a curvature radius of -30.5~32.5mm on the object side and a curvature radius of 11.8~13.5mm on the image side.

5. The autofocus optical imaging system based on a liquid lens according to claim 4, characterized in that, In the first lens group (1), the air gap between the first lens (11) and the second lens (12) is 0.2 mm, and the air gap between the second lens (12) and the third lens (13) is 0.98 mm.

6. The autofocus optical imaging system based on a liquid lens according to claim 1, characterized in that, In the cemented lens, the image-side surface of the fourth lens (34) is cemented to the object-side surface of the fifth lens (35); wherein, The fourth lens (34) has a radius of curvature of 15.2~17.8 mm on the object side and a radius of curvature of -16.5~-14.5 mm on the image side; The fifth lens (35) has a curvature radius of -14.5 to -16.5 mm on the object side and a curvature radius of -38.5 to -35.5 mm on the image side.

7. The autofocus optical imaging system based on a liquid lens according to claim 1, characterized in that, In the second lens group (3), The radius of curvature of the object side of the sixth lens (36) is 41.5~43.5mm, and the radius of curvature of the image side is -79.5~-77.5mm; The seventh lens (37) has a radius of curvature of 85.2~87.5 mm on the object side and a radius of curvature of -59.8~-57.5 mm on the image side; The radius of curvature of the object side of the eighth lens (38) is -9.5~-8.2mm, and the radius of curvature of the image side is -32.5~-29.5mm.

8. The autofocus optical imaging system based on a liquid lens according to claim 7, characterized in that, In the second lens group (3), the air gap between the cemented lens and the sixth lens (36) is 1.02 mm, the air gap between the sixth lens (36) and the liquid lens (4) is 0.25 mm, the air gap between the liquid lens (4) and the seventh lens (37) is 0.21 mm, and the air gap between the seventh lens (37) and the eighth lens (38) is 2.55 mm.

9. The autofocus optical imaging system based on a liquid lens according to claim 1, characterized in that, The aperture stop (2) is located between the first lens group (1) and the second lens group (3), and the air gap along the optical axis to the first lens group (1) is 2.25 mm, and the air gap along the optical axis to the second lens group (3) is 0 mm.

10. The autofocus optical imaging system based on a liquid lens according to claim 1, characterized in that, The back focal length of the second lens group (3) is 2.195 mm, the distance from the second lens group (3) to the cover glass (9) is 1.012 mm, the thickness of the cover glass (9) is 0.55 mm, and the air gap between the CMOS photosensitive surface (10) and the cover glass (9) is 0.75 mm.

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