Variable Magnification Lens Group Aberration Control
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Solution Overview
Problem
Variable magnification optical systems face challenges in reducing aberrations, particularly spherical aberration, at varying magnification due to limitations in the design of lens groups and their movement, which affects the optical performance and weight of the system.
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 the first lens group consists of two or fewer lenses, adhering to specific conditional expressions to optimize focal length, thickness, and movement ratios, thereby reducing aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first lens group consists of multiple lenses to correct aberrations, then aberration correction improves, but the weight of the optical system increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the focal length f1, thickness D1, and movement amount M1 of the first lens group through conditional expressions. This allows effective aberration correction with minimal lenses, reducing weight while maintaining optical performance.
Solution Approach 2:
The optical system is divided into multiple lens groups with the first lens group containing only 1-3 lenses. This segmentation allows the first lens group to be lightweight while other groups handle different optical functions, achieving overall aberration correction without excessive weight.
2Adaptability or versatility
If the first lens group has large movement amount to vary magnification, then magnification range improves, but variations in spherical aberration increase
Solution Approach 1:
The patent controls the movement amount M1 of the first lens group within specific ratios relative to its thickness D1 and focal length f1. This parameter control allows the lens group to achieve required magnification range while maintaining consistent spherical aberration characteristics throughout the movement range.
Solution Approach 2:
The first lens group is designed to move dynamically along the optical axis with controlled amplitude. This dynamic movement enables magnification variation while the controlled movement range prevents excessive spherical aberration changes, balancing versatility and optical quality.
3Weight of moving object
If the first lens group has small thickness to reduce weight, then weight reduction achieves, but manufacturing precision becomes more difficult
Solution Approach 1:
The patent specifies conditional expressions that define appropriate ranges for the thickness D1 relative to focal length f1 and movement amount M1. These parameter relationships ensure the first lens group remains thin enough for weight reduction while maintaining manufacturable dimensions and tolerances.
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 solution effectively reduces variations in aberrations, including spherical aberration, across different magnification states, while minimizing the weight of the optical system by optimizing the lens group configuration and movement.
Implementation Method 1
a first lens group G1 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:7.50<f1/D1<55.00 (1)4.00<M1/D1<22.00 (2)where 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.