Variable Magnification Lens Group Aberration Control
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Solution Overview
Problem
Existing variable magnification optical systems face challenges in reducing variations in aberrations, particularly spherical aberration, across different magnification states due to limitations in the design of lens groups and their movements.
Innovation Solution
A variable magnification optical system comprising six or more lens groups, with a first lens group having positive refractive power and a rear group closer to the image side, where the distances between lens groups are varied, and specific conditional expressions are satisfied to optimize the focal length, thickness, and movement of the first lens group, ensuring reduced aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the first lens group consists of two or fewer lenses, then the weight and complexity of the optical system are reduced, but the ability to correct aberrations across varying magnification states becomes more difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive index and Abbe number of the first lens group's lens material, and by optimizing the focal length and thickness parameters to satisfy specific conditional expressions. This allows the limited number of lenses in the first group to effectively correct aberrations across varying magnification states despite the reduced structural complexity
Solution Approach 2:
The patent applies local quality by assigning specific optical characteristics to the first lens group, requiring it to have positive refractive power and specific refractive index/Abbe number ranges. This localized optimization of optical properties enables effective aberration correction in the critical first group without requiring complex structures throughout the entire optical system
2Reliability
If the first lens group has specific refractive index and Abbe number ranges, then aberration correction is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific ranges for refractive index (1.500-1.700) and Abbe number (20-60) for the first lens group's lens material. These parameter specifications balance aberration correction effectiveness with manufacturability, as the ranges are wide enough to accommodate normal manufacturing variations while still achieving the desired optical performance
3Reliability
If the optical system uses six or more lens groups, then aberration correction capability is improved, but the overall system complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the optical system into six or more lens groups with distinct functions, where the first lens group handles specific aberration correction and subsequent groups handle focusing and image formation. This segmentation allows each group to be optimized independently while working together to achieve overall aberration correction across varying magnification states
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 effectively reduces variations in aberrations, including spherical aberration, across varying magnification states, achieving high optical performance and compact design.
Implementation Method 1
a first lens group having positive refractive power
Data Source
AI summary
A variable magnification optical system including a plurality of lens groups, which is six or more lens groups and comprises a first lens group having positive refractive power and a rear group disposed closer to an image side than the first lens group, is configured so that at varying magnification the distances between the lens groups are varied, the first lens group consists of two or fewer lenses, and both the following conditional expressions are satisfied:8.00<f1/D1<27.001.<M1/D1<12.00where f1 is the focal length of the first lens group, D1 is the thickness of the first lens group on an optical axis, and M1 is the amount of movement of the first lens group at varying magnification from a wide-angle end state to a telephoto end state.