Imaging Lens System Aberration Correction via Segmented Groups
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Solution Overview
Problem
Conventional imaging lens systems face challenges in achieving high optical performance with fast f-numbers and fast focusing speeds, particularly in maintaining uniform image quality across varying shooting distances due to inadequate optical power distribution among lens groups, leading to unsatisfactory aberration correction and increased weight of the focusing group.
Innovation Solution
The imaging lens system is designed with a first lens group, a second lens group, and a third lens group, where the first and third groups remain stationary during focusing, and the second group moves, with specific optical power ratios and conditional formulae ensuring balanced optical performance and reduced focusing group weight, thereby achieving high optical performance and fast focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the optical power of the first lens group is low relative to the third lens group to achieve a compact structure, then the lens system can be made more compact, but spherical aberration cannot be corrected satisfactorily and a large diameter is required to provide a fast f-number
Solution Approach 1:
The first lens group is divided into two sub-groups: a front group and a rear group. The front group has a positive optical power and the rear group has a negative optical power. This segmentation allows the optical power to be distributed more effectively, enabling satisfactory aberration correction while maintaining a compact lens system structure with fast f-number capability.
Solution Approach 2:
Different regions of the first lens group are assigned different optical properties. The front group is designed with positive optical power to converge light, while the rear group is designed with negative optical power to diverge light. This local differentiation of optical quality enables precise control over aberrations throughout the lens system, achieving both compactness and high optical performance.
2Speed
If fewer lens elements are used in the focusing group to reduce weight and achieve faster focusing, then focusing speed improves, but the optical power distribution becomes unbalanced making it difficult to correct aberrations across all shooting distances
Solution Approach 1:
The focusing group (second lens group) is segmented into multiple lens elements with different optical powers. This segmentation allows the group to maintain lower overall weight and shorter movement stroke for fast focusing, while individual elements contribute to aberration correction across different shooting distances, achieving both speed and optical uniformity.
3Weight of moving object
If the optical power of the first lens group is low relative to the second lens group to reduce focusing group weight, then the focusing group becomes lighter for faster focusing, but most of the overall optical power is accounted for by the second lens group making it difficult to correct aberrations from infinity to close-distance shooting
Solution Approach 1:
The first lens group is segmented into front and rear groups with opposite optical signs. This segmentation shifts the optical power distribution balance, reducing the burden on the second lens group while maintaining fast focusing capability. The front group's positive power and rear group's negative power work together to correct aberrations across all shooting distances.
Solution Approach 2:
Specific lens elements within the second lens group are designed with particular optical properties to compensate for the segmented first lens group's power distribution. This local optimization of optical quality in the focusing group enables effective aberration correction while keeping the group lightweight for fast focusing operation.
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 allows for a compact, large-diameter imaging lens system with excellent optical performance and fast focusing speed, maintaining uniform image quality across all shooting distances while reducing the weight and movement stroke of the focusing group, resulting in a lightweight and compact digital appliance.
Implementation Method 1
an imaging lens system includes, from the object side, a first lens group having a positive optical power, a second lens group having a positive optical power, and a third lens group
Data Source
AI summary
An imaging lens system includes first and second lens groups each having a positive optical power (P1, P2) and a third lens group. During focusing, the second lens group moves. When the first lens group is divided into two groups across, as a boundary, the longest aerial distance (t1) among the axial lens-to-lens distances located on the image side of the position of half the total length of the first lens group, the object-side group being a front group and the image-side group being a rear group, the most image-side surface in the front group and the most image-side surface in the rear group are lens surfaces concave to the image side. The conditional formulae 0.2<P1/P<0.6, 0.3<P1/P2<0.9, 0.03<t1/t<0.1, and 0.05<t2/t<0.14 are fulfilled (P, the optical power of the entire system; t2, the aerial distance between the first and second lens groups in the infinity-object-distance condition; t, the total length of the system.