A large-aperture large-target-face zoom optical lens

Abstract

The application discloses a large-aperture large-target-variable optical lens and belongs to the technical field of security monitoring optical lenses. The structure is sequentially arranged from the object side to the image side as a front fixed group, a variable group, a middle fixed group, a compensation group, a rear fixed group and an image surface. The image surface drift is corrected through the cooperation of double motion groups. Three aspheric lenses and four groups of cemented lenses are combined to realize F1.5 constant large aperture, 1-inch large target surface adaptation, full focus segment distortion less than 1%, MTF value greater than 0.5 at 200 lp / mm, matching 4K / 8K ultra-high-definition sensors, and being suitable for low-illumination, high-definition demand scenes such as road monitoring, park security, high-altitude panoramic monitoring and the like.

Description

Technical Field

[0001] This invention belongs to the field of security monitoring optical lens technology, specifically relating to a security zoom optical system suitable for large target area image sensors, large aperture, and multi-focal length continuous zoom. It can be equipped with high-definition / ultra-high-definition security camera equipment and used in scenarios such as road monitoring, park security, and high-altitude panoramic monitoring. Background Technology

[0002] The security monitoring industry is currently developing rapidly towards larger target areas, higher pixel counts, lower illumination, and continuous zoom capabilities, with downstream markets placing multiple stringent performance requirements on zoom lenses:

[0003] 1. The demand for monitoring in low-light scenes continues to increase, requiring lenses with large aperture light-gathering capabilities to achieve clear imaging even at night without supplemental lighting or under weak supplemental lighting conditions;

[0004] 2. With the rapid popularization of 4K / 8K ultra-high-definition imaging technology, the target surface size of the supporting sensors continues to increase, requiring zoom lenses to have the ability to adapt to large target surfaces, excellent full-field aberration correction capabilities, and no significant attenuation of edge resolution;

[0005] 3. The trend of miniaturization in security equipment is obvious, requiring zoom lenses to control size and weight while ensuring imaging performance, and to adapt to the assembly needs of miniaturized bullet cameras and PTZ cameras;

[0006] 4. The upgraded requirements for all-scenario, all-time monitoring necessitate that zoom lenses simultaneously optimize parameters such as distortion, field curvature, and lateral chromatic aberration across the entire focal length, achieving imaging performance close to the diffraction limit and enabling them to be matched with large-area sensors with tens of millions of pixels.

[0007] During actual research and development and testing, the inventors discovered that most mainstream zoom lenses currently on the market cannot meet the above requirements and have the following core technical pain points:

[0008] 1. The aperture parameters are generally smaller than F2.0, resulting in more image noise and insufficient clarity in low-light environments, which cannot meet the imaging requirements of nighttime monitoring without supplementary lighting;

[0009] 2. The maximum compatible target area is mostly below 1 / 1.8 inches, which cannot be matched with 1.1-inch / 1.3-inch large target area ultra-high-definition sensors, resulting in severe edge image quality degradation and prominent problems such as field curvature, distortion, and chromatic aberration;

[0010] 3. The traditional two-group / single compensation group zoom structure is generally adopted, which has limited image plane correction capability: the image plane drift caused by the movement of the zoom group is corrected by only the single compensation group. The amount of image plane drift is large during zooming, and it is difficult to balance aberrations across the entire focal length. Short focal length distortion and long focal length spherical aberration and coma cannot be optimized at the same time.

[0011] 4. To correct the aberrations of large target surfaces across the entire field of view, a large number of redundant lenses are required, resulting in a total lens length generally exceeding 150mm and a heavy weight, which cannot meet the installation requirements of miniaturized security equipment.

[0012] 5. Poor image quality consistency across the entire focal length, with significant fluctuations in sharpness during zooming, failing to meet the requirements for 24-hour uninterrupted high-definition monitoring. Summary of the Invention

[0013] To overcome the aforementioned shortcomings, the inventors of this invention, through long-term exploration, experimentation, and continuous reform and innovation, have proposed a large-aperture, large-surface zoom optical lens that can achieve a constant F1.5 aperture, a 1-inch large surface area, excellent image quality across the entire focal length, and an optical length of less than 120mm, meeting the needs of low-light ultra-high-definition security monitoring.

[0014] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a large aperture and large target surface zoom optical lens, which, from the object side to the image side, consists of: front fixed group A, zoom group B, middle fixed group C, compensation group D, rear fixed group E, and image plane;

[0015] The front fixed group A has positive optical power and is composed of negative meniscus lens A1, positive meniscus lens A2 and positive meniscus lens A3 arranged in order from object to image.

[0016] The zoom group B has negative optical power and consists of biconcave lenses B1, B2, B3, and B4 arranged in order from object to image.

[0017] The intermediate fixed group C has positive optical power and consists of an aperture C1, a positive meniscus lens C2, a positive meniscus lens C3, a negative meniscus lens C4, a positive meniscus lens C5, a positive meniscus lens C6, and a negative meniscus lens C7 arranged in order from the object side to the image side.

[0018] The compensation group D has positive optical power and consists of positive meniscus lens D1, positive meniscus lens D2, biconcave lens D3, and positive meniscus lens D4 arranged in order from object to image.

[0019] The rear fixed group E has negative optical power and consists of a negative meniscus lens E1.

[0020] A further preferred technical solution of the large aperture and large target surface zoom optical lens according to the present invention is as follows: the front fixed group A, the middle fixed group C, and the rear fixed group E are fixed groups, and their positions remain unchanged during zooming; the zoom group B and the compensation group D are independent axial movement groups, and during zooming, the zoom group B and the compensation group D move independently along the axis to cooperate in completing zooming and image plane compensation.

[0021] A further preferred embodiment of the large aperture, large target surface zoom optical lens according to the present invention is that the aperture stop C1 is disposed inside the middle fixed group C near the rear side of the zoom group B.

[0022] A further preferred embodiment of the large aperture, large focal length zoom lens according to the present invention is as follows: a negative meniscus lens A1 and a positive meniscus lens A2 are cemented together to form a first cemented group; a biconcave lens B2 and a positive meniscus lens B3 are cemented together to form a second cemented group; a positive meniscus lens C3 and a negative meniscus lens C4 are cemented together to form a third cemented group; and a positive meniscus lens D2 and a biconcave lens D3 are cemented together to form a fourth cemented group.

[0023] A further preferred technical solution of the large aperture and large target surface zoom optical lens according to the present invention is that the lenses of the first to fourth cemented groups are all paired with high and low dispersion glass, which can simultaneously suppress axial chromatic aberration and transverse chromatic aberration, and control the transverse chromatic aberration of each color of light within ±3μm throughout the entire focal length.

[0024] A further preferred embodiment of the large aperture, large target surface zoom optical lens according to the present invention is that the negative meniscus lens C7, the positive meniscus lens D4, and the negative meniscus lens E1 are double-sided aspherical lenses, and the remaining lenses are spherical lenses.

[0025] A further preferred embodiment of the large aperture, large focal length zoom lens according to the present invention is as follows: when the optical system is in the short focal length position, the ratio of the focal length of the front fixed group A to the focal length of the entire optical system is (3.5, 4.3), the ratio of the focal length of the zoom group B to the focal length of the entire optical system is (-1.33, -1.09), the ratio of the focal length of the middle fixed group C to the focal length of the entire optical system is (1.38, 1.69), the ratio of the focal length of the compensation group D to the focal length of the entire optical system is (1.86, 2.27), and the ratio of the focal length of the rear fixed group E to the focal length of the entire optical system is (-4.9, -4.1).

[0026] A further preferred embodiment of the large aperture, large focal length zoom lens according to the present invention is as follows: when the optical system is in the mid-focal position, the ratio of the focal length of the front fixed group A to the focal length of the entire optical system ranges from (1.73, 2.12), the ratio of the focal length of the zoom group B to the focal length of the entire optical system ranges from (-0.66, -0.54), the ratio of the focal length of the intermediate fixed group C to the focal length of the entire optical system ranges from (0.68, 0.83), the ratio of the focal length of the compensation group D to the focal length of the entire optical system ranges from (0.92, 1.13), and the ratio of the focal length of the rear fixed group E to the focal length of the entire optical system ranges from (-2.43, -1.99).

[0027] A further preferred embodiment of the large aperture, large focal length zoom lens according to the present invention is as follows: when the optical system is in the telephoto position, the ratio of the focal length of the front fixed group A to the focal length of the entire optical system is (1.04, 1.27), the ratio of the focal length of the zoom group B to the focal length of the entire optical system is (-0.40, -0.32), the ratio of the focal length of the middle fixed group C to the focal length of the entire optical system is (0.41, 0.50), the ratio of the focal length of the compensation group D to the focal length of the entire optical system is (0.55, 0.67), and the ratio of the focal length of the rear fixed group E to the focal length of the entire optical system is (-1.46, -1.19).

[0028] A further preferred technical solution of the large aperture, large focal length zoom lens according to the present invention is as follows: the zoom process switches focal lengths through four variable air intervals: d5, d12, d24, and d31. In short focal length mode, d5=1.27mm, d12=24.93mm, d24=5.01mm, and d31=1.71mm; in medium focal length mode, d5=15.77mm, d12=10.43mm, d24=3.19mm, and d31=3.53mm; and in long focal length mode, d5=24.27mm, d12=1.93mm, d24=6.03mm, and d31=0.69mm.

[0029] Compared with the prior art, the technical solution of the present invention has the following advantages / benefits:

[0030] 1. Excellent low-light performance with large aperture: The central fixed group has a built-in aperture stop, combined with multiple high-refractive-index condenser lenses, and a constant F1.5 large aperture throughout the focal length. Compared with the conventional F2.0 aperture, the light intake is increased by 77%, and clear imaging can still be achieved in environments with no or weak supplemental lighting at night, making it suitable for all-weather security monitoring needs.

[0031] 2. Large target surface and high resolution: It is compatible with 1.1-inch / 1.3-inch large target surface image sensors. The meridional and sagittal field curvatures across the entire focal length are controlled within ±0.06mm, the transverse chromatic aberration is controlled within ±3μm, the MTF value at a spatial frequency of 200lp / mm is close to the diffraction limit, and the edge resolution is consistent with the center resolution, which can meet the requirements of 4K / 8K ultra-high-definition imaging.

[0032] 3. Dual motion group image plane stabilization: The zoom group and compensation group move independently and work together to correct image plane drift. Compared with traditional single compensation lenses, the image plane offset at long focal lengths, short focal lengths, and intermediate focal lengths is reduced by more than 90%. No secondary focusing is required throughout the zoom process, making it compatible with automatic zoom security equipment.

[0033] 4. Controllable mass production costs: Only 3 double-sided aspherical lenses are used to correct high-order aberrations, while the rest are all mature spherical lenses. Compared with the all-aspherical solution, the processing, coating and assembly difficulties are significantly reduced, the mass production yield is improved, and the lens manufacturing cost is taken into account. The four cemented lenses are paired with high and low dispersion glass, and the axial chromatic aberration and transverse chromatic aberration are suppressed simultaneously. There is no obvious chromatic aberration across the entire focal length, and the color monitoring screen is pure.

[0034] 5. Compact and miniaturized structure: By optimizing the curvature, air gap and optical power ratio of each lens group, redundant lenses are reduced, with a total of only 19 lenses and an optical length of less than 120mm. Compared with similar large-area zoom lenses, the volume is reduced by 30%, which can be adapted to small assembly spaces such as miniaturized intelligent PTZ cameras, vehicle security, and high-altitude panoramic bullet cameras.

[0035] 6. Balanced image quality across all focal lengths: distortion and field curvature are optimized simultaneously for short focal lengths and wide-angle lenses, and spherical aberration, coma, and chromatic aberration for long focal lengths. MTF, distortion, and chromatic aberration indicators are maintained at a high level across all three focal lengths. The image clarity does not fluctuate significantly during zooming, meeting the needs of 24-hour uninterrupted high-definition security monitoring. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the lens structure of the large aperture, large target surface zoom optical lens of the present invention.

[0038] Figure 2 This is a graph of the MTF modulation transfer function for the short focal length position of this invention.

[0039] Figure 3 This is a graph of the MTF modulation transfer function for the focal length setting in this invention.

[0040] Figure 4 This is a graph of the MTF modulation transfer function for the telephoto lens of this invention.

[0041] Figure 5 This is a graph showing the field curvature and distortion characteristics of the short focal length of this invention.

[0042] Figure 6 This is a curve diagram showing the field curvature and distortion characteristics of the focal length in this invention.

[0043] Figure 7 This is a curve of field curvature and distortion characteristics at the telephoto lens position of this invention.

[0044] Figure 8 This is the vertical axis chromatic aberration curve for the short focal length setting of this invention.

[0045] Figure 9 This is the vertical axis color difference curve diagram of the focal length setting in this invention.

[0046] Figure 10 This is the vertical axis chromatic aberration curve for the telephoto lens position of this invention. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this invention, not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Therefore, the detailed description of the embodiments of this invention provided below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention.

[0048] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

[0049] Example 1:

[0050] like Figure 1 As shown, a large aperture, large target surface zoom optical lens, from object side to image side, consists of: front fixed group A, zoom group B, middle fixed group C, compensation group D, rear fixed group E, and image plane.

[0051] The front fixed group A has positive optical power and consists of negative meniscus lens A1, positive meniscus lens A2, and positive meniscus lens A3 arranged sequentially from the object side to the image side; it undertakes the main light-gathering capability of the system, matches the incident beam with a large aperture, initially corrects primary chromatic aberration and spherical aberration, suppresses the tilt angle of the light rays at the edge of the wide-angle end, and reduces the pressure of subsequent aberration correction.

[0052] The zoom group B has negative optical power and consists of biconcave lenses B1, B2, B3, and B4 arranged in order from object to image. During zooming, the axis moves to change the combined focal length of the system to achieve continuous zoom from wide-angle to telephoto. The cemented group cancels out the zoom chromatic aberration caused by zoom movement and balances the focal aberration of long and short focal lengths.

[0053] The intermediate fixed group C has positive optical power and consists of an aperture stop C1 (the aperture stop can also be represented by STO), positive meniscus lens C2, positive meniscus lens C3, negative meniscus lens C4, positive meniscus lens C5, positive meniscus lens C6, and negative meniscus lens C7 arranged in order from the object side to the image side. The aperture stop C1 controls the light-passing aperture to achieve a large aperture, multiple positive lenses enhance the light-gathering ability of the system, the cemented group corrects the transverse chromatic aberration, and the aspherical surface corrects the field curvature and distortion in a large field of view.

[0054] The compensation group D has positive optical power and consists of positive meniscus lens D1, positive meniscus lens D2, biconcave lens D3, and positive meniscus lens D4 arranged in order from object to image. It moves nonlinearly in conjunction with the zoom group B to accurately compensate for the image plane shift caused by the zoom group movement. The double-sided aspherical surface further corrects the remaining astigmatism and field curvature.

[0055] The rear fixed group E has negative optical power and is composed of a negative meniscus lens E1; it matches the beam angle of the large target sensor image plane, corrects residual distortion and transverse chromatic aberration of the system, and makes the imaging light perpendicular to the photosensitive chip, thereby improving the uniformity of edge pixel response.

[0056] The front fixed group A, the middle fixed group C, and the rear fixed group E are fixed groups, and their positions remain unchanged during zooming; the zoom group B and the compensation group D are independent axial movement groups. During zooming, both the zoom group B and the compensation group D move independently along the axis to cooperate in completing zooming and image plane compensation.

[0057] The aperture C1 is located inside the middle fixed group C, near the rear side of the zoom group B.

[0058] Negative meniscus lens A1 and positive meniscus lens A2 are cemented together to form the first cemented group; biconcave lens B2 and positive meniscus lens B3 are cemented together to form the second cemented group; positive meniscus lens C3 and negative meniscus lens C4 are cemented together to form the third cemented group; and positive meniscus lens D2 and biconcave lens D3 are cemented together to form the fourth cemented group. The cemented groups use high- and low-dispersion glass for matching, effectively canceling axial and transverse chromatic aberration in the system, significantly reducing the difficulty of correcting chromatic aberration at long and short focal lengths, and avoiding stray light from air gaps caused by multiple single lenses.

[0059] The lenses of the first to fourth cemented groups are all paired with high and low dispersion glass, which can simultaneously suppress axial chromatic aberration and transverse chromatic aberration, and control the transverse chromatic aberration of each color of light within ±3μm across the entire focal length.

[0060] The negative meniscus lens C7, positive meniscus lens D4, and negative meniscus lens E1 are double-sided aspherical lenses. They utilize the higher-order terms of aspherical lenses to correct high-order distortions, field curvature, and coma in a large field of view, reducing the number of lenses used and shortening the overall length of the lens. The remaining lenses are all spherical lenses. The processing, coating, and assembly processes for spherical lenses are mature, reducing mass production costs and processing difficulty, while balancing optical performance and mass production feasibility.

[0061] Let f be the real-time focal length of the entire optical system. fA, fB, fC, fD, and fE are the focal lengths of the front fixed group A, zoom group B, intermediate fixed group C, compensation group D, and rear fixed group E, respectively. The ratio of each group's focal length to the total focal length of the system is limited as follows: When the optical system is at the short focal length position (wide-angle end), the ratio of the focal length of the front fixed group A to the total focal length of the optical system is (3.5, 4.3), the ratio of the focal length of the zoom group B to the total focal length of the optical system is (-1.33, -1.09), the ratio of the focal length of the intermediate fixed group C to the total focal length of the optical system is (1.38, 1.69), the ratio of the focal length of the compensation group D to the total focal length of the optical system is (1.86, 2.27), and the ratio of the focal length of the rear fixed group E to the total focal length of the optical system is (-4.9, -4.1).

[0062] When the optical system is in the center focal position, it is in the middle setting. The ratio of the focal length of the front fixed group A to the focal length of the entire optical system ranges from (1.73, 2.12), the ratio of the focal length of the zoom group B to the focal length of the entire optical system ranges from (-0.66, -0.54), the ratio of the focal length of the intermediate fixed group C to the focal length of the entire optical system ranges from (0.68, 0.83), the ratio of the focal length of the compensation group D to the focal length of the entire optical system ranges from (0.92, 1.13), and the ratio of the focal length of the rear fixed group E to the focal length of the entire optical system ranges from (-2.43, -1.99).

[0063] When the optical system is at the telephoto end, the ratio of the focal length of the front fixed group A to the focal length of the entire optical system ranges from (1.04, 1.27), the ratio of the focal length of the zoom group B to the focal length of the entire optical system ranges from (-0.40, -0.32), the ratio of the focal length of the middle fixed group C to the focal length of the entire optical system ranges from (0.41, 0.50), the ratio of the focal length of the compensation group D to the focal length of the entire optical system ranges from (0.55, 0.67), and the ratio of the focal length of the rear fixed group E to the focal length of the entire optical system ranges from (-1.46, -1.19). This optical power ratio achieves: controllable distortion over a large field of view at the wide-angle end, effective compression of the overall length at the telephoto end, reasonable travel of the zoom and compensation groups, low difficulty in manufacturing the cam structure, and balanced optical power across the entire focal length range, reducing various aberrations at their source.

[0064] This system has a total of 33 optical surfaces, including multiple sets of spherical and aspherical lenses. The curvature radius, center thickness, air gap, Nd refractive index of the optical glass, and Vd Abbe number of each lens are detailed in Table 1 below. High and low refractive index and high and low dispersion optical glass are selected to balance the needs of chromatic aberration correction and large aperture light transmission.

[0065] Table 1 Physical parameters of each lens

[0066] The zoom system features variable air gaps (four groups of movement gaps: d5 / d12 / d24 / d31). The zoom process relies on the changes in these four air gaps—d5 (gap before and after zoom group B), d12, d24, and d31 (gap before and after compensation group D)—to switch focal lengths. See Table 2 below for the detailed values ​​of the three focal length intervals.

[0067] Table 2 Variable interval positions for each focal length group

[0068] The aspherical surface shape adopts the standard polynomial aspherical equation, where K is the conic constant, and A4, A6, A8, A10, A12... are the aspherical coefficients of the 4th, 6th, 8th, 10th and 12th orders, respectively. By precisely adjusting the coefficients of the higher-order terms, the high-order field curvature and distortion of the large target surface full field of view are suppressed.

[0069] The equation for an aspherical surface is as follows:

[0070]

[0071] The definition of aspherical shapes is explained below:

[0072] y: Radial coordinate starting from the optical axis;

[0073] z: The offset of the optical axis direction starting from the intersection point of the aspherical surface and the optical axis;

[0074] r: The radius of curvature of the reference sphere for the aspherical surface;

[0075] Table 3 shows the coefficients of the aspherical surfaces 23, 24, 30, 31, 32, and 33 (all coefficients are unitless), along with A4, A6, A8, A10, A12 and the conic constant k.

[0076] Table 3 Aspherical Parameters

[0077] This invention achieves excellent image quality across the entire focal length by using a multi-ply achromatic aberration correction system, a three-element double-sided aspherical surface for higher-order aberration correction, and a zoom / compensation dual-motion system to collaboratively compensate for image plane errors. The evaluation indicators are as follows:

[0078] 1. MTF Modulation Transfer Function

[0079] like Figures 2-4As shown, the MTF curves for the short, medium, and long focal lengths (0~6.5mm image height) are close to the diffraction limit; the resolution attenuation from the center to the edge is minimal, and it still possesses a high OTF coefficient at a high frequency of 200lp / mm, perfectly matching 4K / 8K large-area high-pixel sensors. The vertical axis in the figure represents the ratio of the contrast of the output image to the contrast of the input object, with values ​​between 0 and 1, and no unit; in the figure, T represents meridional or tangential rays, and S represents sagittal or radial rays. In the diagram: Black line: represents the diffraction limit; Blue line (image height 0.0000mm): represents the imaging performance at the center of the image; Green line (image height 2.6000mm): represents the imaging performance at position 0.4 (i.e., 40% of the sensor's full field of view); Red line (image height 4.6000mm): represents the imaging performance at position 0.7 (i.e., 70% of the sensor's full field of view); Yellow-green line (image height 5.9000mm): represents the imaging performance at position 0.9 (i.e., 90% of the sensor's full field of view); Purple line (image height 6.5500mm): represents the full field of view imaging performance at the edge positions.

[0080] 2. Field curvature and distortion correction like Figures 5-7 As shown, the meridional T and sagittal S-field curvatures across the entire focal length are controlled within ±0.06mm; the positive distortion at the wide-angle end is controllable, and the negative distortion at the telephoto end is small. The overall field-of-view distortion meets the national standards for security monitoring, and the image shows no obvious stretching or compression distortion. The vertical axis in the figure represents the normalized maximum field of view and has no units. The blue line in the figure has a wavelength of 0.46μm, the green line has a wavelength of 0.52μm, and the red line has a wavelength of 0.63μm. The corresponding S and T values ​​represent the meridional T and sagittal S-field curvatures for the corresponding wavelengths.

[0081] 3. Vertical axis color difference correction like Figures 8-10 As shown, the chromatic aberration of all colors across the entire focal length is controlled within ±3μm, close to the size of the Airy disk. There is no chromatic aberration or ghosting at the image edges, and the color reproduction consistency is high. The vertical axis in the figure represents the maximum field of view normalized and has no unit. The wavelength of the blue line in the figure is 0.46μm, the wavelength of the green line is 0.52μm, and the wavelength of the red line is 0.63μm.

[0082] The large-aperture, large-surface zoom lens provided in this embodiment has a total of 19 elements, including the first to fourth cemented lens groups and 3 double-sided aspherical elements. The focal length range is 8mm-40mm, with a zoom ratio of 5x and a constant aperture of F1.5 throughout the entire focal length. It is compatible with 1.1-inch / 1.3-inch 8MP / 12MP CMOS sensors, and has a total optical length of 118mm. The field of view is 72° at the short focal length, with a full-field distortion ≤4%, and full-field distortion ≤1.5% at medium and long focal lengths. The meridional and sagittal field curvatures are ≤±0.06mm throughout the entire focal length, and the transverse chromatic aberration is ≤±3μm. The MTF curve at a spatial frequency of 200lp / mm is close to the diffraction limit. The zoom process switches focal lengths through four variable air gaps: d5, d12, d24, and d31. The cam groove design is simple, resulting in a low load on the drive motor. The image plane offset is less than 5μm throughout the entire focal length, and clear imaging can still be achieved at an object distance of 1m.

[0083] This embodiment uses four sets of cemented lenses paired with high and low dispersion glass to correct axial and transverse chromatic aberration across the entire focal length, and three double-sided aspherical lenses to correct higher-order aberrations such as field curvature, distortion, and coma. The zoom group and compensation group work together to ensure image plane stability during zooming. The spherical lens accounts for more than 84% of the total image. The processing, coating, and assembly processes are mature, resulting in high mass production yield and controllable costs. While achieving a large aperture, large target surface, and high resolution, it maintains a compact structural size and can be widely used in various scenarios such as road monitoring, park security, high-altitude panoramic monitoring, forest fire prevention, and vehicle security, meeting the needs of all-weather, ultra-high-definition monitoring.

Claims

1. A large-aperture, large-aperture zoom optical lens, characterized in that, From object to image, the order is: front fixed group A, zoom group B, intermediate fixed group C, compensation group D, rear fixed group E, image plane; The front fixed group A has positive optical power and is composed of negative meniscus lens A1, positive meniscus lens A2 and positive meniscus lens A3 arranged in order from object to image. The zoom group B has negative optical power and consists of biconcave lenses B1, B2, B3, and B4 arranged in order from object to image. The intermediate fixed group C has positive optical power and consists of an aperture C1, a positive meniscus lens C2, a positive meniscus lens C3, a negative meniscus lens C4, a positive meniscus lens C5, a positive meniscus lens C6, and a negative meniscus lens C7 arranged in order from the object side to the image side. The compensation group D has positive optical power and consists of positive meniscus lens D1, positive meniscus lens D2, biconcave lens D3, and positive meniscus lens D4 arranged in order from object to image. The rear fixed group E has negative optical power and consists of a negative meniscus lens E1.

2. The large aperture, large target surface zoom optical lens according to claim 1, characterized in that, The front fixed group A, the middle fixed group C, and the rear fixed group E are fixed groups, and their positions remain unchanged during zooming; the zoom group B and the compensation group D are independent axial movement groups. During zooming, both the zoom group B and the compensation group D move independently along the axis to cooperate in completing zooming and image plane compensation.

3. The large aperture, large target surface zoom optical lens according to claim 1, characterized in that, The aperture C1 is located inside the middle fixed group C, near the rear side of the zoom group B.

4. The large aperture, large target surface zoom optical lens according to claim 1, characterized in that, Negative meniscus lens A1 and positive meniscus lens A2 are cemented together to form the first cemented group; biconcave lens B2 and positive meniscus lens B3 are cemented together to form the second cemented group; positive meniscus lens C3 and negative meniscus lens C4 are cemented together to form the third cemented group; positive meniscus lens D2 and biconcave lens D3 are cemented together to form the fourth cemented group.

5. A large-aperture, large-surface zoom optical lens according to claim 4, characterized in that, The lenses of the first to fourth cemented groups are all paired with high and low dispersion glass, which can simultaneously suppress axial chromatic aberration and transverse chromatic aberration, and control the transverse chromatic aberration of each color of light within ±3μm across the entire focal length.

6. A large-aperture, large-surface zoom optical lens according to claim 1, characterized in that, The negative meniscus lens C7, positive meniscus lens D4, and negative meniscus lens E1 are double-sided aspherical lenses, while the remaining lenses are spherical lenses.

7. A large-aperture, large-surface zoom optical lens according to claim 1, characterized in that, When the optical system is in the short focal length position, the ratio of the focal length of the front fixed group A to the focal length of the entire optical system ranges from (3.5, 4.3), the ratio of the focal length of the zoom group B to the focal length of the entire optical system ranges from (-1.33, -1.09), the ratio of the focal length of the intermediate fixed group C to the focal length of the entire optical system ranges from (1.38, 1.69), the ratio of the focal length of the compensation group D to the focal length of the entire optical system ranges from (1.86, 2.27), and the ratio of the focal length of the rear fixed group E to the focal length of the entire optical system ranges from (-4.9, -4.1).

8. A large-aperture, large-surface zoom optical lens according to claim 1, characterized in that, When the optical system is in the center focal position, the ratio of the focal length of the front fixed group A to the focal length of the entire optical system ranges from (1.73, 2.12), the ratio of the focal length of the zoom group B to the focal length of the entire optical system ranges from (-0.66, -0.54), the ratio of the focal length of the intermediate fixed group C to the focal length of the entire optical system ranges from (0.68, 0.83), the ratio of the focal length of the compensation group D to the focal length of the entire optical system ranges from (0.92, 1.13), and the ratio of the focal length of the rear fixed group E to the focal length of the entire optical system ranges from (-2.43, -1.99).

9. A large-aperture, large-surface zoom optical lens according to claim 1, characterized in that, When the optical system is at the telephoto position, the ratio of the focal length of the front fixed group A to the focal length of the entire optical system ranges from (1.04, 1.27), the ratio of the focal length of the zoom group B to the focal length of the entire optical system ranges from (-0.40, -0.32), the ratio of the focal length of the intermediate fixed group C to the focal length of the entire optical system ranges from (0.41, 0.50), the ratio of the focal length of the compensation group D to the focal length of the entire optical system ranges from (0.55, 0.67), and the ratio of the focal length of the rear fixed group E to the focal length of the entire optical system ranges from (-1.46, -1.19).

10. A large-aperture, large-surface zoom optical lens according to claim 1, characterized in that, The zoom process involves switching focal lengths via four variable air intervals: D5, D12, D24, and D31. In short focal length mode, D5=1.27mm, D12=24.93mm, D24=5.01mm, and D31=1.71mm; in medium focal length mode, D5=15.77mm, D12=10.43mm, D24=3.19mm, and D31=3.53mm; and in long focal length mode, D5=24.27mm, D12=1.93mm, D24=6.03mm, and D31=0.69mm.

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