Four-Group Zoom Lens With Negative Focus Group for Wide-Angle Imaging
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Solution Overview
Problem
Existing zoom lenses for imaging apparatuses face challenges in achieving a balance between reducing size and weight, maintaining high optical performance, and minimizing aberration fluctuations while supporting high-speed focusing and a wide angle of view.
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 first and third lens groups move during zooming and focusing, with specific refractive index and Abbe number conditions met to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first lens group is made large to achieve wide angle of view and high speed focusing, then optical performance is improved, but lens size and weight increase
Solution Approach 1:
The patent applies parameter changes by carefully selecting the refractive index (Nd1) and Abbe number (vd1) of the first lens, as well as the refractive index (Nd3) and Abbe number (vd3) of the third lens. By satisfying specific conditional expressions relating these optical parameters to the focal length (fw) and other lens characteristics, the design achieves optimal balance between optical performance and compact size, allowing the first lens group to be smaller while maintaining wide angle of view and high speed focusing capabilities
2Weight of moving object
If the lens structure is simplified to reduce size, then portability is improved, but aberration control becomes difficult
Solution Approach 1:
The patent uses parameter changes by establishing specific relationships between the optical parameters of the first lens (Nd1, vd1) and third lens (Nd3, vd3) and the overall lens characteristics (fw, f3, Bf, IH). These conditional expressions ensure that even with a simplified compact structure, aberrations remain well-controlled across the entire imaging distance range
Solution Approach 2:
The patent employs composite material principles by combining lenses with different refractive indices and Abbe numbers. The first lens group contains a negative lens (L1a) and positive lens (L1c) with specific material properties, while the third lens group uses a negative lens (L3a) with carefully selected material characteristics. This composite approach allows compact design while maintaining excellent aberration correction
3Speed
If the third lens group moves during focusing, then focusing speed is improved, but aberration fluctuation increases
Solution Approach 1:
The patent applies parameter changes by optimizing the focal length (f3) of the third lens group and its material properties (Nd3, vd3) to satisfy specific conditional expressions. These parameters are carefully tuned to ensure that when the third lens group moves for high-speed focusing, the resulting aberration fluctuations are minimized, achieving both fast focusing and stable optical performance
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, while ensuring a wide angle of view and effective vibration reduction.
Implementation Method 1
a first lens group G1 that has a negative refractive power; a second lens group G2 that has a positive refractive power; a third lens group G3 that has a negative refractive power; and a fourth lens group G4 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.