Imaging Lens Focus Group Segmentation for Aberration Control
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Solution Overview
Problem
Existing imaging lenses face challenges in achieving favorable optical performance, particularly in maintaining aberration correction and reducing weight and size while accommodating a small F number and large angle of view.
Innovation Solution
The imaging lens configuration includes a first lens group that remains stationary during focusing, with a second lens group moving, featuring a negative meniscus lens closest to the image side and a positive refractive power, along with specific conditional expressions to optimize lens curvatures and Abbe numbers, ensuring effective aberration correction and reduced weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a conventional imaging lens configuration is used, then the lens can achieve basic imaging function, but the weight and size of the focus group increases
Solution Approach 1:
The lens is divided into a stationary first lens group and a movable second lens group. By segmenting the lens system, the focus group (second lens group) can be made lighter and smaller while the first lens group remains stationary to provide stable aberration correction. This segmentation allows the moving part to be minimized in weight and size while maintaining overall optical performance.
Solution Approach 2:
Different lens groups are assigned different functions: the first lens group is optimized for aberration correction with specific curvature and Abbe number requirements, while the second lens group is optimized for focusing with a negative meniscus lens configuration. This local optimization allows each group to perform its function efficiently without compromising the other.
2Illumination intensity
If the F number is reduced for better light gathering, then the angle of view increases, but aberration correction becomes more difficult
Solution Approach 1:
The patent specifies particular parameter ranges for the lens elements, including curvature radii (rF/Y between 0.7-1.3, (rF-rR)/(rF+rR) between -0.2-0.2) and Abbe numbers (ν1 between 20-50, ν2 between 15-40). These parameter optimizations enable the lens to maintain aberration correction even with reduced F number and increased angle of view.
Solution Approach 2:
The second lens group is designed to move during focusing to dynamically adjust the optical path. The negative meniscus lens configuration in the second group allows for dynamic compensation of aberrations that occur at different object distances, enabling maintained performance across varying F numbers and angles of view.
3Reliability
If more lens elements are added to improve optical performance, then aberration correction improves, but the device complexity increases
Solution Approach 1:
The lens is segmented into two functional groups with clear division of labor. The first group handles stationary aberration correction while the second group handles dynamic focusing. This segmentation achieves good optical performance without requiring a large number of separate lens elements, thus controlling device complexity.
Solution Approach 2:
The second lens group serves multiple functions: it provides the primary focusing mechanism and simultaneously contributes to aberration correction through its negative meniscus lens design. This multi-functionality reduces the need for additional dedicated correction elements, simplifying the overall lens configuration.
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
This configuration achieves reduced weight and size of the focus group while maintaining high optical performance, minimizing aberration fluctuations, and supporting a small F number and large angle of view.
Implementation Method 1
a lens closest to the image side in the second lens group is a negative meniscus lens having a surface convex toward the object side
Data Source
AI summary
The imaging lens includes, successively in order from a position closest to an object side to an image side: a first lens group; and a second lens group that has a positive refractive power. During focusing, only the second lens group moves. A lens closest to the image side in the second lens group is a negative meniscus lens having a surface convex toward the object side. Assuming that a paraxial radius of curvature of an object side surface of the negative meniscus lens closest to the image side in the second lens group is rF, and a maximum image height is Y, the imaging lens satisfies Conditional Expression (1), which is represented by 0.5<rF/Y<3 (1).