Zoom Optical System Aberration Correction via Lens Group Segmentation
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Solution Overview
Problem
Conventional zoom optical systems for cameras have insufficient optical performance, particularly in terms of aberration correction during zooming and focusing.
Innovation Solution
A zoom optical system comprising a first lens group with positive refractive power, a second lens group with negative refractive power, and a subsequent group with a focusing group having negative refractive power, where the distances between these groups change upon zooming, and the refractive indices of the lenses are optimized to satisfy specific conditional expressions for effective aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional zoom optical system configurations are used, then the system structure is simple, but optical performance is insufficient
Solution Approach 1:
The zoom optical system is divided into multiple lens groups (first lens group with positive refractive power, second lens group with negative refractive power, and subsequent groups) that can move independently during zooming and focusing operations. This segmentation allows each group to be optimized for specific functions, improving overall optical performance while managing complexity through modular design
Solution Approach 2:
Different lens groups are assigned specific refractive powers and movement characteristics tailored to their functions. The first lens group has positive refractive power for primary focusing, the second has negative refractive power for zooming, and subsequent groups have optimized properties for aberration correction. This local optimization of optical properties enhances overall system performance
2Reliability
If a large barrel is used to accommodate lens groups, then aberration correction is improved, but the system becomes heavy and slow for autofocus
Solution Approach 1:
The patent optimizes the refractive indices of lenses within each group to satisfy specific conditional expressions (0.85 < n1P/n1N < 1.00). This parameter optimization allows effective aberration correction through precise control of light refraction, eliminating the need for oversized mechanical structures
Solution Approach 2:
The patent replaces reliance on large mechanical barrel structures with optimized optical parameters (refractive indices). By using precisely controlled refractive properties of lens materials, the system achieves aberration correction without requiring heavy mechanical support structures, enabling faster and lighter autofocus operation
3Reliability
If lens groups are positioned to correct aberrations at all focal lengths, then optical performance is improved, but the system becomes complex to manufacture
Solution Approach 1:
The lens groups are designed with dynamic movement capabilities along the optical axis during zooming and focusing. The first and second lens groups move relative to each other to maintain optimal positioning for aberration correction across different focal lengths, rather than requiring fixed complex arrangements. This dynamic approach simplifies manufacturing while maintaining performance
Solution Approach 2:
The lens groups are designed to perform multiple functions simultaneously: the first lens group with positive refractive power handles both focusing and contributes to zooming, the second lens group with negative refractive power handles zooming while assisting in aberration correction. This multi-functionality reduces the number of specialized components needed, simplifying manufacturing
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 successful aberration correction, including spherical and chromatic aberrations, across various focal lengths and distances, resulting in improved optical performance and a compact, lightweight design that enables quick and silent autofocus without a large barrel.
Implementation Method 1
a first lens group having positive refractive power; a second lens group having negative refractive power... n1P denotes a refractive index of a lens with largest positive refractive power in the first lens group
Data Source
AI summary
A zoom optical system comprises, in order from an object: a first lens group (G1) having positive refractive power; a second lens group (G2) having negative refractive power; and a subsequent group (GR) having at least one lens group. Upon zooming, distances between the first lens group (G1) and the second lens group (G2) and between the second lens group (G2) and the subsequent group (GR) change. The subsequent group (GR) comprises a focusing group (Gfc) having negative refractive power for focusing. The first lens group (G1) comprises a 1-1st lens having positive refractive power and is disposed closest to the object. A following conditional expression is satisfied:0.85<n1P/n1N<1.00where,n1P denotes a refractive index of a lens with largest positive refractive power in the first lens group, andn1N denotes a refractive index of a lens with largest negative refractive power in the first lens group.