Zoom Lens System Aberration Correction via Segmented Groups
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Solution Overview
Problem
Existing high zoom-ratio zoom lens systems face challenges in achieving a zoom ratio exceeding 13:1 with a long focal length of 350 mm and an f-number of 5.6, while maintaining optical quality and correcting aberrations such as spherical and chromatic aberrations.
Innovation Solution
A high zoom-ratio zoom lens system comprising a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group, where the positive third lens group includes a positive first sub-lens group and a negative second sub-lens group, with specific refractive power conditions and lens element arrangements to correct aberrations and maintain a small f-number.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a high zoom-ratio zoom lens system is designed with more lens groups to achieve zoom ratio exceeding 13:1, then the zoom ratio is improved, but the device complexity increases
Solution Approach 1:
The lens system is divided into four distinct lens groups with specific refractive power characteristics. The third lens group is further segmented into two sub-lens groups that move relative to each other during zooming. This segmentation enables the system to achieve a zoom ratio exceeding 13:1 while managing complexity through functional division.
Solution Approach 2:
The patent employs dynamic movement of lens groups along the optical axis during zooming. Specifically, the third lens group's two sub-lens groups move relative to each other, and the distances between lens groups are adjusted dynamically. This dynamic configuration allows the system to achieve high zoom ratio while maintaining optical quality throughout the zoom range.
2Length of moving object
If the focal length is increased to 350 mm at the long focal length extremity, then the telephoto capability is improved, but the f-number becomes slower
Solution Approach 1:
The patent carefully controls the refractive power parameters of each lens group to achieve the desired focal length while maintaining a fast f-number. By optimizing the combined refractive powers and adjusting the distances between lens groups, the system achieves 350 mm focal length with f-number 5.6, preventing the f-number from becoming too slow.
3Length of moving object
If the half angle-of-view is increased to approximately 60° at the short focal length extremity, then the wide-angle capability is improved, but spherical aberration increases
Solution Approach 1:
Different lens groups are designed with specific local optical characteristics to address different aberration problems. The first lens group has positive refractive power for wide-angle coverage, the second lens group has negative refractive power to control spherical aberration, and the third lens group with its two movable sub-lens groups provides additional aberration correction. This local optimization enables 60° half angle-of-view while controlling spherical aberration.
Solution Approach 2:
The second lens group with negative refractive power acts as an intermediary element between the first and third lens groups. It specifically counteracts spherical aberration generated by the wide-angle first lens group, enabling the system to achieve 60° half angle-of-view without excessive spherical aberration.
4Adaptability or versatility
If the distance between lens groups is adjusted dynamically during zooming, then the zoom ratio is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs dynamic movement of lens groups along the optical axis during zooming. Specifically, the third lens group's two sub-lens groups move relative to each other, and the distances between lens groups are adjusted dynamically. This dynamic configuration allows the system to achieve high zoom ratio while maintaining optical quality throughout the zoom range.
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 system achieves a zoom ratio exceeding 13:1, a focal length of 350 mm at the long focal length extremity, an f-number of 5.6, and a half angle-of-view of approximately 60° at the short focal length extremity, effectively correcting spherical and chromatic aberrations.
Implementation Method 1
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
Implementation Method 2
The cemented lens includes a positive lens element and a negative lens element, in this order from the object
Implementation Method 3
effectively correcting spherical and chromatic aberrations
Data Source
AI summary
A zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group, in this order from an object. Upon zooming from the short focal length extremity to the long focal length extremity, the distance between the first and the second lens groups increases, and the distance between the second and the third lens groups decreases. The third lens group includes a positive first sub-lens group and a negative second sub-lens group, in this order from the object. The first sub-lens group comprises a positive lens element provided at the most object-side thereof and a cemented lens provided at the most image-side thereof. The cemented lens includes a positive lens element and a negative lens element, in this order from the object.