Zoom Lens Aberration Control via Segmented Group Design
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Solution Overview
Problem
Existing zoom lenses with small image circles struggle to maintain optical performance when enlarged to accommodate larger sensor sizes, leading to increased aberrations, particularly off-axis aberrations, while also requiring a significant increase in size.
Innovation Solution
A zoom lens configuration comprising a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with varying refractive power, and a fourth lens group with positive refractive power, where the first and fifth lens groups remain stationary during zooming, and the second and third lens groups move along the optical axis, with specific focal length ratios and curvature conditions to minimize aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the lens system is proportionally enlarged to correspond with a larger image circle, then the image circle size increases, but off-axis aberration increases significantly
Solution Approach 1:
The patent applies local quality by giving different functional characteristics to different parts of the lens system. Specifically, the first lens group has a positive refractive power with specific curvature relationships (|R1| < |R2|) to correct off-axis aberrations locally, while other lens groups have different refractive powers to handle different portions of the optical path differently, thereby controlling aberrations across the enlarged image circle without uniform enlargement of the entire system
Solution Approach 2:
The patent changes key optical parameters including the refractive powers of different lens groups, the curvature radii relationships (|R1| < |R2|), and the focal length ratios (0.3 < |f2/f1| < 1.0) to optimize the balance between image circle size and aberration control. These parameter adjustments allow the system to achieve a large image circle while maintaining acceptable off-axis aberration levels
2Area of stationary object
If the lens system is proportionally enlarged to correspond with a larger image circle, then the image circle size increases, but the size of the entire system increases significantly
Solution Approach 1:
The patent segments the lens system into five distinct lens groups with different refractive powers and movement characteristics. This segmentation allows each group to be optimized for specific functions (e.g., first lens group for aberration correction, second for compactness) rather than uniformly enlarging the entire system, thereby achieving a large image circle while controlling overall system size
Solution Approach 2:
The patent utilizes the zooming dimension by allowing the second, third, and fourth lens groups to move along the optical axis during zooming, while keeping the first and fifth lens groups stationary. This selective movement in the optical axis dimension enables compact system design with large image circle capability without requiring proportional enlargement of all components
3Volume of stationary object
If the first lens group has a positive refractive power, then the overall system size can be reduced, but off-axis aberration becomes more difficult to control
Solution Approach 1:
The patent applies local quality by giving the first lens group a positive refractive power optimized for compactness while simultaneously specifying curvature relationships (|R1| < |R2|) to correct off-axis aberrations locally at the front element, preventing the usual trade-off between compactness and aberration control
Solution Approach 2:
The patent uses the second lens group with negative refractive power as an intermediary element between the first (positive) and third lens groups. This negative power group acts as a mediator to balance the aberrations introduced by the positive power groups while maintaining compact system size, effectively decoupling the size-aberration trade-off
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 solution enables a zoom lens with a large image circle and favorable optical performance while keeping the overall system size small, effectively reducing aberrations and maintaining image quality across zoom ranges.
Implementation Method 1
a first b lens group that moves along an optical axis during focusing and has a positive refractive power
Implementation Method 2
a first lens group that has a positive refractive power, a second lens group that has a negative refractive power, a third lens group that has a refractive power, a fourth lens group that has a positive refractive power, and a fifth lens group that has a positive refractive power
Data Source
AI summary
The zoom lens consists of, in order from an object side, a positive first lens group, a negative second lens group, a third lens group, a positive fourth lens group, and a positive fifth lens group. During zooming, the second lens group, the third lens group, and the fourth lens group move. The first lens group consists of, in order from an object side, a negative first a lens group, a positive first b lens group that moves during focusing, and a positive first c lens group. A most-image-side lens of the first b lens group is a negative meniscus lens having a convex surface facing an object side.