Imaging system

Abstract

This invention relates to an imaging system comprising a fixed group (G1), a focusing group (G2), and a stop. The fixed group (G1) includes at least two lenses, and the focusing group (G2) includes at least four lenses. The fixed group (G1) and the focusing group (G2) are arranged sequentially along the optical axis from the object side to the image side. The imaging system of this invention possesses advantages such as low distortion, large depth of field, uniform image quality, good color reproduction, high contrast, no temperature drift problem, high resolution, and low chromatic aberration.

Description

Technical Field

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

[0002] Machine vision refers to the process of collecting light signals through a machine vision lens and feeding them to a camera. The camera then converts the light signals into electrical signals, which are transmitted to an image processing system. The system performs various calculations based on the acquired image information to extract target features, and finally controls the actions of equipment on-site based on the judgment results. In the era of industrial automation, the demand for machine vision has been increasing year by year, and it has been widely used in fields such as electronics manufacturing, defect detection, and precision measurement.

[0003] Imaging systems used in machine vision have very high requirements for pixels, image uniformity, distortion, brightness, and color reproduction. However, current machine vision lenses on the market have large distortion, uneven brightness, difficulty in displaying image details, low dynamic range, and poor color and contrast.

[0004] Furthermore, the speed of lens updates cannot keep up with the changing pace of market demands, which is particularly limiting in high-precision, high-tech fields where high image quality is required. Summary of the Invention

[0005] One object of the present invention is to solve the above-mentioned problems and to provide an imaging system.

[0006] To achieve the above-mentioned objective, the present invention provides an imaging system comprising a fixed group, a focusing group, and an aperture stop. The fixed group comprises at least two lenses, and the focusing group comprises at least four lenses. The fixed group and the focusing group are arranged sequentially from the object side to the image side along the optical axis.

[0007] According to one aspect of the invention, the aperture is located in the fixed group.

[0008] Alternatively, the aperture stop is located between the fixed group and the focusing group, and the optical power of the first lens located on the image side of the aperture stop is positive.

[0009] According to one aspect of the invention, the fixing group has at least one positive lens and one negative lens;

[0010] The lens closest to the object side in the fixed group is a positive lens, and its object side is convex.

[0011] The lens closest to the image side in the fixed group is a negative lens, and its image side is concave.

[0012] According to one aspect of the invention, the focusing group has at least two positive lenses and two negative lenses, wherein at least two lenses form a cemented doublet lens group.

[0013] According to one aspect of the invention, the optical power of both the fixing group and the focusing group is positive;

[0014] When imaging an object from infinity to a nearby object, focusing is achieved by the focusing group moving along the optical axis.

[0015] According to one aspect of the invention, the focal length value f1 of the fixed group and the focal length value f2 of the focusing group satisfy: 0.5 ≤ |f1 / f2| ≤ 3.5.

[0016] According to one aspect of the invention, the focal length value f2 of the focusing group and the focal length value f of the imaging system satisfy: 0.6 ≤ |f2 / f| ≤ 2.4.

[0017] According to one aspect of the invention, the total length L of the imaging system and the focal length f of the imaging system satisfy: 1.3 ≤ |L / f| ≤ 1.6.

[0018] According to one aspect of the invention, in the focusing group, the focal length f21 of the lens near the object side and the focal length f22 of the lens near the image side in at least one of the cemented doublet lens groups satisfy: -2≤f21 / f22≤-0.7.

[0019] According to one aspect of the invention, in the focusing group, the focal length of the lens near the object side of the doublet lens group is positive, and its Abbe number vd and refractive index nd satisfy: 15≤vd≤55, 1.65≤nd≤2.10 respectively.

[0020] According to the concept of this invention, an imaging system is provided that features low distortion, large depth of field, uniform image quality, good color reproduction, high contrast, solves the temperature drift problem, high resolution, and low chromatic aberration. In this system, the fixed group is located on the object side of the focusing group along the optical axis. This ensures that the focal length value does not differ significantly at different object distances and provides better resolution.

[0021] According to one aspect of the present invention, the imaging system includes a fixed group and a focusing group arranged sequentially along the optical axis from the object side to the image side. The fixed group includes at least two lenses, and the focusing group includes at least four lenses. The fixed group and the focusing group are arranged sequentially along the optical axis from the object side to the image side. Both the fixed group and the focusing group have positive optical power. When imaging from an object at infinity to a closer object, focusing is achieved by moving the focusing group along the optical axis. The fixed group mainly functions to collect light, ensuring smooth entry of light into the imaging system, thereby reducing the system's tolerance sensitivity. It can also correct chromatic aberration, ensuring good color reproduction and improving the image quality of the imaging system. The main function of the focusing group is to ensure clear imaging of the optical system at different object distances, while correcting aberrations and distortions, reducing the system's tolerance sensitivity, and thus ensuring high image quality and image uniformity close to the diffraction limit.

[0022] According to one embodiment of the invention, the aperture stop is disposed in the fixed group. Alternatively, the aperture stop is disposed between the fixed group and the focusing group, and the optical power of the first lens located on its image side along the optical axis is positive. This is beneficial for improving the image quality of the optical system, bringing it close to the diffraction limit and ensuring image uniformity.

[0023] According to one aspect of the present invention, the fixed assembly includes at least one positive lens and one negative lens. The lens closest to the object side is the positive lens, and its object-side surface is convex; the lens closest to the image side is the negative lens, and its image-side surface is concave. This combination of positive and negative lenses helps ensure smooth entry of the light beam into the optical system and corrects chromatic aberration, thereby reducing the tolerance sensitivity of the imaging system, ensuring color reproduction, and improving image quality.

[0024] According to one aspect of the present invention, the focusing group has at least two positive lenses and two negative lenses, wherein at least two lenses form a cemented doublet. Thus, by matching the optical power of the positive and negative lenses and using the cemented doublet, it is beneficial to correct aberrations within the focusing group. Correction of aberrations within the focusing group helps reduce the burden of aberration correction on the fixed group, thereby reducing the tolerance sensitivity of the optical system and comprehensively improving the imaging quality of the optical system.

[0025] According to one aspect of the present invention, the focal length f1 of the fixed group and the focal length f2 of the focusing group satisfy: 0.5 ≤ |f1 / f2| ≤ 3.5. This ensures imaging quality from near object distance to infinity by rationally matching the positive and negative optical powers and their magnitudes between the fixed and focusing groups. The focal length f2 of the focusing group and the focal length f of the imaging system satisfy: 0.6 ≤ |f2 / f| ≤ 2.4. If the value is less than the lower limit of the above formula, the optical power borne by the focusing group is too large, resulting in low tolerance sensitivity between groups; if the value is greater than the upper limit of the above formula, the focusing performance is low, and it is not conducive to achieving a long back focal length and a small principal ray incident angle. Only by satisfying the above formula can a good balance between tolerance sensitivity and focusing performance be achieved, while ensuring a sufficient back focal length and a small principal ray incident angle.

[0026] According to one aspect of the present invention, the total length L of the imaging system and the focal length f of the imaging system satisfy: 1.3 ≤ |L / f| ≤ 1.6. Satisfying this relationship ensures the imaging quality of the optical system, resulting in fine image quality, uniform image quality, and high contrast. In the focusing group, the focal length f21 of the lens near the object side and the focal length f22 of the lens near the image side in at least one cemented doublet group satisfy: -2 ≤ f21 / f22 ≤ -0.7. Satisfying this relationship is beneficial for correcting aberrations in the optical system and solving the temperature drift problem, while simultaneously ensuring the imaging quality of the imaging system while reducing system tolerance sensitivity. In the focusing group, the focal length of the lens near the object side in the cemented doublet group is positive, and the Abbe value vd and refractive index nd of this lens satisfy: 15 ≤ vd ≤ 55, 1.65 ≤ nd ≤ 2.10, respectively. This effectively corrects chromatic aberration in the imaging system, improves the imaging quality of the imaging system, and also facilitates temperature drift correction in the anechoic system. Attached Figure Description

[0027] Figure 1 A schematic diagram illustrating the structure of an imaging system according to a first embodiment of the present invention;

[0028] Figure 2-4 These are the distortion, magnification chromatic aberration, and positional chromatic aberration diagrams when focusing at the optimal working distance in the first embodiment.

[0029] Figure 5 and Figure 6 These are the subject-object distance MTF curve and the defocus MTF curve in the first embodiment, respectively.

[0030] Figure 7 A schematic diagram illustrating the structure of an imaging system according to a second embodiment of the present invention;

[0031] Figure 8-10 These are the distortion, magnification chromatic aberration, and positional chromatic aberration diagrams when focusing at the optimal working distance in the second embodiment.

[0032] Figure 11 and Figure 12 These are the subject-object distance MTF curve and the defocus MTF curve in the second implementation method, respectively.

[0033] Figure 13 A schematic diagram illustrating the structure of an imaging system according to a third embodiment of the present invention;

[0034] Figure 14-16 These are the distortion, magnification chromatic aberration, and positional chromatic aberration diagrams when focusing at the optimal working distance in the third embodiment.

[0035] Figure 17 and Figure 18 These are the subject-object distance MTF curve and the defocus MTF curve in the third implementation method, respectively.

[0036] Figure 19 A schematic diagram illustrating the structure of an imaging system according to a fourth embodiment of the present invention;

[0037] Figure 20-22 These are the distortion, magnification chromatic aberration, and positional chromatic aberration diagrams when focusing at the optimal working distance in the fourth embodiment.

[0038] Figure 23 and Figure 24 These are the subject-object distance MTF curve and the defocus MTF curve in the fourth implementation method, respectively.

[0039] Figure 25 A schematic diagram illustrating the structure of an imaging system according to a fifth embodiment of the present invention;

[0040] Figure 26-28 These are the distortion, magnification chromatic aberration, and positional chromatic aberration diagrams when focusing at the optimal working distance in the fifth embodiment.

[0041] Figure 29 and Figure 30 These are the subject-object distance MTF curve and the defocus MTF curve in the fifth implementation method, respectively. Detailed Implementation

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0043] When describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" express orientations or positional relationships based on the orientations or positional relationships shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on the present invention.

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0045] See Figure 1The imaging system of the present invention includes a fixed group G1 and a focusing group G2 arranged sequentially along the optical axis from the object side to the image side. The fixed group G1 includes at least two lenses, and the focusing group G2 includes at least four lenses. Both the fixed group G1 and the focusing group G2 have positive optical powers. When imaging from an object at infinity to a closer object, focusing is achieved by the focusing group G2 moving along the optical axis. The fixed group G1 primarily functions to collect light, ensuring smooth light entry into the imaging system and thus reducing system tolerance sensitivity. Additionally, the fixed group G1 can correct chromatic aberration, ensuring good color reproduction and improving image quality. The main function of the focusing group G2 is to ensure clear imaging of the optical system at different object distances, while simultaneously correcting aberrations and distortions, reducing system tolerance sensitivity, and thus ensuring near-diffraction-limited high image quality and image uniformity.

[0046] In addition, the present invention also includes a stop aperture, in Figure 1 In the illustrated embodiment, the first lens, located between the fixed group G1 and the focusing group G2, and situated on the image side of the aperture along the optical axis, has a positive optical power; Figure 7 In the illustrated embodiment, the stop is located in the fixed group G1. Therefore, in this invention, the stop can be located in either of these two positions. This is beneficial for improving the image quality of the optical system, bringing it closer to the diffraction limit, and ensuring image uniformity.

[0047] In this invention, the fixed assembly G1 has at least one positive lens and one negative lens. The lens closest to the object side is the positive lens, and its object side is convex; the lens closest to the image side is the negative lens, and its image side is concave. This combination of positive and negative lenses helps ensure smooth entry of the light beam into the optical system and corrects chromatic aberration, thereby reducing the tolerance sensitivity of the imaging system, ensuring color reproduction, and improving image quality.

[0048] In this invention, the focusing group G2 has at least two positive lenses and two negative lenses, with at least two lenses forming a cemented doublet, i.e., at least one cemented doublet. Thus, the combination of optical power of the positive and negative lenses and the use of cemented plates facilitate the correction of aberrations within the focusing group G2. The correction of aberrations within the focusing group G2 reduces the burden of aberration correction on the fixed group G1, thereby reducing the tolerance sensitivity of the optical system and comprehensively improving the imaging quality of the optical system.

[0049] In this invention, the focal length f1 of the fixed group G1 and the focal length f2 of the focusing group G2 satisfy: 0.5 ≤ |f1 / f2| ≤ 3.5. Thus, by reasonably matching the positive and negative optical powers and their magnitudes in the fixed group G1 and the focusing group G2, imaging quality from near object distance to infinity can be guaranteed.

[0050] The focal length f2 of focusing group G2 and the focal length f of the imaging system satisfy the following condition: 0.6 ≤ |f2 / f| ≤ 2.4. If the value is less than the lower limit of the above formula, the optical focal length handled by focusing group G2 is too large, resulting in low tolerance sensitivity between groups; if the value is greater than the upper limit of the above formula, the focusing performance is low, and it is not conducive to achieving a long back focal length and a small principal ray incident angle. Only by satisfying the above formula can a good balance between tolerance sensitivity and focusing performance be achieved, while ensuring a sufficient back focal length and a small principal ray incident angle.

[0051] The total length L of the imaging system (i.e., the distance from the object-side surface of the lens closest to the object to the image plane) and the focal length f of the imaging system satisfy: 1.3 ≤ |L / f| ≤ 1.6. Satisfying this relationship ensures the imaging quality of the optical system, resulting in fine image quality, uniform image quality, and high contrast. In the focusing group G2, the focal lengths f21 of the lens closest to the object and f22 of the lens closest to the image in at least one cemented doublet satisfy: -2 ≤ f21 / f22 ≤ -0.7. Satisfying this relationship helps correct aberrations in the optical system and solve temperature drift problems, while simultaneously ensuring the imaging quality of the imaging system while reducing system tolerance sensitivity. In the focusing group G2, the focal length of the lens closest to the object in the cemented doublet is positive, and the Abbe value vd and refractive index nd of this lens satisfy: 15 ≤ vd ≤ 55 and 1.65 ≤ nd ≤ 2.10, respectively. In this way, the chromatic aberration of the imaging system can be effectively corrected, the imaging quality of the imaging system can be improved, and the temperature drift correction of the calorimetric system can be facilitated.

[0052] In summary, the imaging system of this invention achieves high-quality imaging by rationally distributing glass with different refractive indices. Furthermore, it possesses excellent resolution, with image quality approaching the diffraction limit. Simultaneously, this imaging system boasts advantages such as low distortion, high image quality, uniform image quality, delicate image texture, rich colors, and high contrast. Moreover, it has a wide imaging object distance range, with a maximum focusing object distance of infinity and a minimum focusing object distance of less than 0.05m. Additionally, the imaging system of this invention has high overall transmittance and uniform image brightness. It also solves the temperature drift problem, achieving clear imaging without refocusing within a temperature range of -40℃ to 80℃. Furthermore, the system exhibits good tolerances for individual components and assembly, demonstrating excellent manufacturability.

[0053] The imaging system of the present invention is described in detail below with five embodiments based on the above-described configuration. In each of the following embodiments, sur1, sur2, ..., surN are used to represent the surfaces of each lens, wherein the cemented surface of the cemented lens group is considered as one surface, and the aperture is considered as STOP. The parameter settings of each embodiment satisfy the following Table 1:

[0054]

[0055] Table 1

[0056] First implementation method:

[0057] like Figure 1 As shown, in this embodiment, the fixed group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged sequentially along the optical axis, wherein the second lens L2 and the third lens L3 form a cemented doublet. The focusing group G2 includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8 arranged sequentially along the optical axis. The fifth lens L5 and the sixth lens L6 form a cemented doublet. In this embodiment, the aperture stop (STOP) is located between the fixed group G1 and the focusing group G2.

[0058] In this embodiment, the parameters of the imaging system are as follows:

[0059] The system's total length (TTL, or L) is 64.2 mm, its focal length (f) is 49.5 mm, its imaging object distance range is 0.05 m to inf, its F-number (FNO) is 2, and other parameters are shown in Table 2 below.

[0060] # type radius thickness nd vd sur1 standard 35 2.2 1.95 18.0 sur2 standard 65 1.4 sur3 standard 18 4.96 1.59 68.6 sur4 standard 254 3.15 1.73 28.3 sur5 standard 15 4 Stop standard Inf 6 sur7 standard 25 3.9 (Articulated) 1.7 55.5 sur8 standard -132.8 0.31 sur9 standard -61.8 5.8 1.95 18.0 sur10 standard -17 5.9 1.85 23.8 sur11 standard 30 1.8 sur12 standard 30 2.1 1.90 31.3 sur13 standard -288 6 sur14 standard -15 5 1.62 36.3 sur15 standard -19 11.9 (Articulated) Image

[0061] Table 2

[0062] Combination Figure 2-6 As can be seen, the imaging system of this embodiment achieves high-quality imaging, excellent resolution, and image quality approaching the diffraction limit. Simultaneously, it exhibits low distortion, uniform image quality, fine detail, rich colors, and high contrast. Furthermore, it has a wide imaging object distance range, with a maximum focusing object distance of infinity and a minimum focusing object distance of less than 0.05m. Additionally, it boasts high overall transmittance and uniform image brightness. It also effectively addresses temperature drift issues, achieving clear imaging without refocusing within a temperature range of -40℃ to 80℃. Moreover, the system exhibits good tolerances for individual components and assembly, demonstrating excellent manufacturability.

[0063] Second implementation method:

[0064] like Figure 7 As shown, in this embodiment, the fixed group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged sequentially along the optical axis. The focusing group G2 includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8 arranged sequentially along the optical axis. The fifth lens L5 and the sixth lens L6 form a cemented doublet lens group. In this embodiment, the aperture stop (STOP) is located between the second lens L2 and the third lens L3 in the fixed group G1.

[0065] In this embodiment, the parameters of the imaging system are as follows:

[0066] The system's total length (TTL) is 68 mm, its focal length (f) is 50 mm, its imaging object distance range is 0.05 m to inf, and its F-number (FNO) is 2. Other parameters are shown in Table 3 below.

[0067] # type radius thickness nd vd sur1 standard 51.9 2.2 1.49 70.4 sur2 standard 247.9 0.36 sur3 standard 26.7 2.2 1.73 54.7 sur4 standard 54.9 2.9 Stop standard Inf 2.6 sur6 standard 62.3 2.7 1.62 36.3 sur7 standard 29.6 11.8 sur8 standard 44.5 5.9 (Articulated) 1.62 63.4 sur9 standard 293.9 0.9 sur10 standard 87.6 5.8 1.95 18 sur11 standard -29.7 4.7 1.74 27.8 sur12 standard 17.8 5.9 sur13 standard 44.5 3.6 1.87 40.7 sur14 standard -47.5 0.9 sur15 standard -29.7 5.3 1.65 33.8 sur16 standard Inf 10.6 (Articulated) Image

[0068] Table 3

[0069] Combination Figure 8-12 As can be seen, the imaging system of this embodiment achieves high-quality imaging, excellent resolution, and image quality approaching the diffraction limit. Simultaneously, it exhibits low distortion, uniform image quality, fine detail, rich colors, and high contrast. Furthermore, it has a wide imaging object distance range, with a maximum focusing object distance of infinity and a minimum focusing object distance of less than 0.05m. Additionally, it boasts high overall transmittance and uniform image brightness. It also effectively addresses temperature drift issues, achieving clear imaging without refocusing within a temperature range of -40℃ to 80℃. Moreover, the system exhibits good tolerances for individual components and assembly, demonstrating excellent manufacturability.

[0070] The third implementation method:

[0071] like Figure 13 As shown, in this embodiment, the fixed group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged sequentially along the optical axis, wherein the second lens L2 and the third lens L3 form a cemented doublet. The focusing group G2 includes a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8 arranged sequentially along the optical axis. The fourth lens L4 and the fifth lens L5 form a cemented doublet. In this embodiment, the aperture stop (STOP) is located between the fixed group G1 and the focusing group G2.

[0072] In this embodiment, the parameters of the imaging system are as follows:

[0073] The system's total length (TTL) is 58 mm, its focal length (f) is 49.2 mm, its imaging object distance range is 0.05 m to inf, and its F-number (FNO) is 2. Other parameters are shown in Table 4 below.

[0074] # type radius thickness nd vd sur1 standard 38.5 0.3 1.75 52.3 sur2 standard 177 0.2 sur3 standard 21 5 1.5 81.6 sur4 standard -251 3.7 1.74 27.8 Sur5 standard 25.5 3.2 Stop standard Inf 8.4 sur7 standard 21 5 (Articulated) 1.92 20.9 sur8 standard -23 2 1.92 24 sur9 standard 13 4 sur10 standard 23 2 1.59 61.2 sur11 standard 110 5 sur12 standard 60 1.7 1.91 35.3 sur13 standard -48 3.9 sur14 standard -39.5 1.2 1.71 27.8 sur15 standard 78.5 10.5 (Articulated) Image

[0075] Table 4

[0076] Combination Figure 14-18As can be seen, the imaging system of this embodiment achieves high-quality imaging, excellent resolution, and image quality approaching the diffraction limit. Simultaneously, it exhibits low distortion, uniform image quality, fine detail, rich colors, and high contrast. Furthermore, it has a wide imaging object distance range, with a maximum focusing object distance of infinity and a minimum focusing object distance of less than 0.05m. Additionally, it boasts high overall transmittance and uniform image brightness. It also effectively addresses temperature drift issues, achieving clear imaging without refocusing within a temperature range of -40℃ to 80℃. Moreover, the system exhibits good tolerances for individual components and assembly, demonstrating excellent manufacturability.

[0077] Fourth implementation method:

[0078] like Figure 19 As shown, in this embodiment, the fixed group G1 includes a first lens L1, a second lens L2, and a third lens L3 arranged sequentially along the optical axis. The focusing group G2 includes a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged sequentially along the optical axis. The fourth lens L4 and the fifth lens L5 form a cemented doublet lens group. In this embodiment, the aperture stop (STOP) is located between the fixed group G1 and the focusing group G2.

[0079] In this embodiment, the parameters of the imaging system are as follows:

[0080] The system's total length (TTL) is 61.9 mm, its focal length (f) is 49.4 mm, its imaging object distance range is 0.05 m to inf, and its F-number (FNO) is 2. Other parameters are shown in Table 5 below.

[0081] # type radius thickness nd vd sur1 standard 27 3.4 1.5 81.6 sur2 standard Inf 8.9 sur3 standard 22 2.2 1.59 61.2 sur4 standard 42.5 4.3 sur5 standard -105 4.6 1.64 34.5 sur6 standard 19.7 2.5 Stop standard Inf 7 sur8 standard 20 3 (Articulated) 1.72 50.4 sur9 standard -40 3 1.65 33.8 sur10 standard 17.5 3.5 sur11 standard 100 2.3 1.8 35 sur12 standard -25 4 sur13 standard 30 3.1 1.73 28.3 sur14 standard 15 10.9 (Articulated) Image

[0082] Table 5

[0083] Combination Figure 20-24 As can be seen, the imaging system of this embodiment achieves high-quality imaging, excellent resolution, and image quality approaching the diffraction limit. Simultaneously, it exhibits low distortion, uniform image quality, fine detail, rich colors, and high contrast. Furthermore, it has a wide imaging object distance range, with a maximum focusing object distance of infinity and a minimum focusing object distance of less than 0.05m. Additionally, it boasts high overall transmittance and uniform image brightness. It also effectively addresses temperature drift issues, achieving clear imaging without refocusing within a temperature range of -40℃ to 80℃. Moreover, the system exhibits good tolerances for individual components and assembly, demonstrating excellent manufacturability.

[0084] Fifth implementation method:

[0085] like Figure 25As shown, in this embodiment, the fixed group G1 includes a first lens L1 and a second lens L2 arranged sequentially along the optical axis. The focusing group G2 includes a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged sequentially along the optical axis. The fourth lens L4 and the fifth lens L5 form a cemented doublet lens group. In this embodiment, the aperture stop (STOP) is located between the fixed group G1 and the focusing group G2.

[0086] In this embodiment, the parameters of the imaging system are as follows:

[0087] The system's total length (TTL) is 59.2 mm, its focal length (f) is 50.3 mm, its imaging object distance range is 0.05 m to inf, and its F-number (FNO) is 2. Other parameters are shown in Table 6 below.

[0088] # type radius thickness Nd vd sur1 standard 21 3.5 1.5 81.6 sur2 standard 100 8 sur3 standard Inf 2 1.64 34.5 sur4 standard 50 5 Stop standard Inf 8 sur6 standard 30 2 (Articulated) 1.52 64.2 sur7 standard 80 3 sur8 standard 30 3 1.72 50.4 sur9 standard -40 3 1.65 33.8 sur10 standard 37 3.5 sur11 standard -70 3 1.8 35 sur12 standard -25 4 sur13 standard 28 2 1.73 28.3 sur14 standard 14 9 (Articulated) Image

[0089] Table 6

[0090] Combination Figure 26-30 As can be seen, the imaging system of this embodiment achieves high-quality imaging, excellent resolution, and image quality approaching the diffraction limit. Simultaneously, it exhibits low distortion, uniform image quality, fine detail, rich colors, and high contrast. Furthermore, it has a wide imaging object distance range, with a maximum focusing object distance of infinity and a minimum focusing object distance of less than 0.05m. Additionally, it boasts high overall transmittance and uniform image brightness. It also effectively addresses temperature drift issues, achieving clear imaging without refocusing within a temperature range of -40℃ to 80℃. Moreover, the system exhibits good tolerances for individual components and assembly, demonstrating excellent manufacturability.

[0091] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements 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 imaging system comprising two lens groups: a fixed group (G1), a focusing group (G2), and an aperture stop (STOP), wherein the fixed group (G1) comprises at least two lenses, characterized in that, The fixed group (G1) and the focusing group (G2) are arranged sequentially from the object side to the image side along the optical axis, and the optical power of both the fixed group (G1) and the focusing group (G2) is positive. When imaging an object from infinity to a nearby object, focusing is achieved by the focusing group (G2) moving along the optical axis; Along the optical axis from the object side to the image side, the fixed group (G1) includes a first lens (L1) with positive optical power, a second lens (L2) with positive optical power, and a third lens (L3) with negative optical power, for a total of three lenses; the focusing group (G2) includes a fourth lens (L4) with positive optical power, a fifth lens (L5) with negative optical power, a sixth lens (L6) with positive optical power, and a seventh lens (L7) with negative optical power, for a total of four lenses; Alternatively, along the optical axis from the object side to the image side, the fixed group (G1) includes a first lens (L1) with positive optical power, a second lens (L2) with positive optical power, and a third lens (L3) with negative optical power, for a total of three lenses; along the optical axis from the object side to the image side, the focusing group (G2) includes a fourth lens (L4) with positive optical power, a fifth lens (L5) with optical power, a sixth lens (L6) with optical power, a seventh lens (L7) with positive optical power, and an eighth lens (L8) with negative optical power, for a total of five lenses, wherein the optical power of the fifth lens (L5) is opposite to that of the sixth lens (L6). Alternatively, along the optical axis from the object side to the image side, the fixed group (G1) includes a first lens (L1) with positive optical power and a second lens (L2) with negative optical power, for a total of two lenses; the focusing group (G2) includes a third lens (L3) with positive optical power, a fourth lens (L4) with positive optical power, a fifth lens (L5) with negative optical power, a sixth lens (L6) with positive optical power, and a seventh lens (L7) with negative optical power, for a total of five lenses.

2. The imaging system according to claim 1, characterized in that, The stop is located in the fixed group (G1). Alternatively, the stop is located between the fixed group (G1) and the focusing group (G2), and the first lens on the image side of the stop has a positive optical power.

3. The imaging system according to claim 1, characterized in that, The lens closest to the object side in the fixed group (G1) is a positive lens, and its object side is convex. The lens closest to the image side in the fixed group (G1) is a negative lens, and its image side is concave. The fixed group (G1) includes a positive lens, a positive lens, and a negative lens arranged sequentially along the optical axis from the object side to the image side, for a total of three lenses; Alternatively, the fixed group (G1) may include a positive lens and a negative lens arranged sequentially along the optical axis from the object side to the image side, for a total of two lenses.

4. The imaging system according to claim 1, characterized in that, When the optical power combination of the focusing group (G2) is "positive-positive-negative-positive-negative", the second and third lenses in the focusing group (G2) along the optical axis from the object side to the image side form a cemented doublet lens group. When the optical power combination of the focusing group (G2) is "positive-negative-positive-positive-negative" or "positive-negative-positive-negative", the first lens and the second lens along the optical axis from the object side to the image side in the focusing group (G2) form a cemented doublet.

5. The imaging system according to any one of claims 1-4, characterized in that, The focal length f1 of the fixed group (G1) and the focal length f2 of the focusing group (G2) satisfy: 0.5≤|f1 / f2|≤3.

5.

6. The imaging system according to any one of claims 1-4, characterized in that, The focal length f2 of the focusing group (G2) and the focal length f of the imaging system satisfy: 0.6≤|f2 / f|≤2.

4.

7. The imaging system according to any one of claims 1-4, characterized in that, The total length L of the imaging system and the focal length f of the imaging system satisfy: 1.3≤|L / f|≤1.

6.

8. The imaging system according to claim 4, characterized in that, In the focusing group (G2), the focal length f21 of the lens near the object side and the focal length f22 of the lens near the image side in the doublet lens group satisfy: -2≤f21 / f22≤-0.

7.

9. The imaging system according to claim 4, characterized in that, In the focusing group (G2), the focal length of the lens closest to the object side of the doublet lens group is positive, and its Abbe number vd and refractive index nd satisfy: 15≤vd≤55, 1.65≤nd≤2.10 respectively.

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