Zoom Lens Design with Aspherical Groups for Wide Angle and Low F-Number
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Solution Overview
Problem
Existing zoom lenses either lack a wide angle of view and high magnification or have a low F-number, and often come with complex structures that increase size and weight, failing to meet the requirements of modern digital cameras and video cameras for high resolution and brightness.
Innovation Solution
A zoom lens design comprising a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, where the second lens group includes aspherical lenses with specific refractive indices and the third lens group includes multiple lenses with varying refractive powers, allowing for a wide angle of view, high magnification, and low F-number while minimizing size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a zoom lens is designed with a wide angle of view and high magnification, then the field of view and magnification capability are improved, but the F-number increases (brightness decreases) and the structure becomes more complex
Solution Approach 1:
The zoom lens is divided into four distinct lens groups (first with positive power, second with negative power, third with positive power, and fourth with positive power), each serving specific optical functions. This segmentation allows independent optimization of each group to achieve wide angle of view while controlling F-number through coordinated movement of the groups during zooming
Solution Approach 2:
The distances between the first, second, third, and fourth lens groups are made variable during zooming operations. By dynamically adjusting the spacing between lens groups, the system maintains optimal optical performance across the zoom range, achieving both wide angle of view and controlled F-number through adaptive configuration
2Illumination intensity
If a zoom lens is designed with high magnification and low F-number, then the brightness and magnification capability are improved, but the lens structure becomes complicated causing increased size and weight
Solution Approach 1:
The second lens group incorporates aspherical lenses (with at least one having negative refractive power and another with positive refractive power) to correct spherical aberration and other optical imperfections. This reduces the need for additional correction lenses, simplifying the overall structure while maintaining high brightness and controlling F-number across the zoom range
Solution Approach 2:
Specific refractive index requirements are imposed on lenses in the second group (nd2≥2.0) and third group (Vd3≥70), and specific focal length ratios are maintained (2≤tf/wf≤5). These parameter constraints enable achieving low F-number and high magnification with a more compact and simpler lens configuration
3Weight of moving object
If a zoom lens structure is simplified to reduce size and weight, then the portability is improved, but the ability to achieve wide angle of view, high magnification, and low F-number simultaneously is degraded
Solution Approach 1:
The lens system combines materials with different optical properties, including aspherical lenses with high refractive indices (nd2≥2.0) in the second group and lenses with high Abbe numbers (Vd3≥70) in the third group. This composite material approach enables achieving wide angle of view, high magnification, and low F-number simultaneously with fewer elements, reducing overall weight while maintaining full optical performance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves a wide angle of view, high magnification, and low F-number, ensuring high brightness and efficient aberration control, thereby addressing the limitations of existing lenses and providing a compact and functional optical solution for digital cameras and video cameras.
Implementation Method 1
a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, where the first lens group, the second lens group, the third lens group, and the fourth lens group are arranged sequentially from an object side
Implementation Method 2
the second lens group includes a first aspherical lens having a negative refractive power, and a second aspherical lens having a positive refractive power
Data Source
AI summary
A zoom lens and a photographing apparatus having the zoom lens including a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a positive refractive power; and a fourth lens group having a positive refractive power, wherein the first lens group, the second lens group, the third lens group, and the fourth lens group are arranged sequentially from an object side, wherein the second lens group includes a first aspherical lens having a negative refractive power, and a second aspherical lens having a positive refractive power.