Four-Group Zoom Lens for Compact, Fast Focusing
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Solution Overview
Problem
Existing zoom lenses for imaging apparatuses face challenges in achieving a small size and lightweight design while maintaining high optical performance and minimizing aberration fluctuations due to object distance, and they struggle to balance wide-angle view, high-speed focusing, and aberration suppression.
Innovation Solution
A zoom lens configuration comprising a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a fourth lens group with positive refractive power, where the third lens group moves during focusing, and the lens groups' distances change during zooming, adhering to specific conditional expressions to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the first lens group is made large to achieve wide angle of view and high speed focusing, then the focusing performance is improved, but the overall lens size increases
Solution Approach 1:
The lens is divided into four lens groups (G1, G2, G3, G4) with alternating positive and negative refractive powers. Each group has a specific function: G1 and G2 form a positive power subsystem for wide-angle performance, while G3 and G4 form a negative power subsystem for focusing. This segmentation allows the first lens group to be smaller while maintaining focusing speed through the coordinated movement of the third lens group.
2Weight of moving object
If the lens configuration is optimized for reduction in size, then portability is improved, but optical performance and aberration suppression deteriorate
Solution Approach 1:
Each lens group is assigned specific local optical properties: G1 and G2 have positive refractive powers optimized for wide-angle light gathering, while G3 and G4 have negative refractive powers optimized for aberration correction. The third lens group (G3) specifically consists of a negative lens with optimized refractive index and Abbe number to suppress chromatic aberrations. This local optimization of optical properties in different regions of the lens system maintains high optical performance while enabling compact overall design.
3Stability of the object's composition
If the lens groups are configured to minimize aberration fluctuations, then optical consistency is improved, but device complexity increases
Solution Approach 1:
The lens groups are configured to move dynamically during zooming operations. The first and second lens groups move together as a positive power subsystem, while the third and fourth lens groups move together as a negative power subsystem. This dynamic configuration allows the optical system to maintain stable aberration characteristics across different focal lengths by coordinating the movement of lens groups with alternating refractive powers.
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 configuration achieves high optical performance with minimal aberration fluctuations, supports high-speed focusing, and reduces lens size and weight, enhancing portability and functionality in imaging apparatuses.
Implementation Method 1
a first lens group that has a negative refractive power, a second lens group that has a positive refractive power, a third lens group that has a negative refractive power, and a fourth lens group that has a positive refractive power
Data Source
AI summary
The zoom lens consists of, in order from the object side, a first lens group that has a negative refractive power; a second lens group that has a positive refractive power; a third lens group that has a negative refractive power; and a fourth lens group that has a positive refractive power. During zooming, in each lens group, distances between the adjacent groups in the direction of the optical axis are changed. The first lens group consists of, in order from the object side, a first lens having a negative refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power. The third lens group consists of a negative lens. During focusing, only the third lens group moves along the optical axis. The zoom lens satisfies predetermined conditional expressions.