Variable Magnification Optical System for Aberration Control
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Solution Overview
Problem
Existing variable magnification optical systems in cameras face challenges in maintaining consistent optical performance across varying magnification, particularly in reducing aberrations such as spherical and coma aberrations, due to imbalances in lens group focal lengths and movements.
Innovation Solution
A variable magnification optical system is designed with specific conditional expressions to control the focal length ratios between lens groups, ensuring the first lens group is fixed relative to the image plane while varying spacings between adjacent lens groups, and incorporating lens groups with balanced refractive powers to minimize aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the spacings between lens groups are varied to change magnification, then the magnification range is improved, but spherical and coma aberrations increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the focal length ratios between lens groups through conditional expressions. By maintaining specific relationships between f1, f2, and f3, the system optimizes aberration correction across the magnification range. This involves adjusting optical parameters such as focal lengths and spacing distances to balance magnification capability with aberration control.
Solution Approach 2:
The optical system is segmented into multiple lens groups with distinct functions. The first lens group (negative refractive power) and subsequent lens groups (positive refractive power) are separated and can move independently. This segmentation allows each group to be optimized for specific purposes: the first group for aberration correction and the subsequent groups for magnification control, thereby resolving the contradiction between magnification range and aberration control.
2Adaptability or versatility
If lens groups are moved to vary magnification, then the magnification capability is improved, but the optical performance consistency deteriorates
Solution Approach 1:
The patent implements dynamic control of lens group movements to maintain optical performance consistency across varying magnification. By defining specific movement relationships and spacing variations between lens groups during magnification changes, the system dynamically adjusts the optical configuration to preserve image quality. This dynamic approach ensures that performance metrics remain stable despite changes in magnification capability.
Solution Approach 2:
The system maintains optical performance consistency through parameter changes by enforcing conditional expressions on focal length ratios. These expressions ensure that as lens groups move to achieve different magnifications, the fundamental optical parameters remain within optimized ranges, preventing performance degradation and maintaining reliability across the full magnification range.
3Device complexity
If the first lens group is fixed relative to the image plane, then the structure is simplified, but the ability to correct aberrations is reduced
Solution Approach 1:
The patent resolves this contradiction through segmentation by separating the aberration correction function from the magnification control function. The first lens group is fixed and dedicated to aberration correction, while the subsequent lens groups handle magnification changes. This functional segmentation allows each group to be optimized independently, maintaining aberration correction capability while simplifying the overall structure by eliminating the need for the first group to move.
Solution Approach 2:
The fixed first lens group acts as an intermediary that preprocesses the light before it reaches the movable subsequent lens groups. This intermediary structure performs initial aberration correction, reducing the burden on the movable groups and enabling them to focus primarily on magnification control, thereby maintaining correction capability while simplifying the dynamic structure.
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 spherical and coma aberrations across different magnification settings, maintaining high optical performance without increasing system size.
Implementation Method 1
a first lens group having negative refractive power and a subsequent lens group including a plurality of lens groups... both having positive refractive power
Data Source
AI summary
A variable magnification optical system including, in order from an object side, a first lens group having negative refractive power and a subsequent lens group including a plurality of lens groups is configured so that the subsequent lens group includes second and third lens groups in order from the object side, both having positive refractive power, that at varying magnification, the first lens group is fixed with respect to an image plane, and the spacings between adjacent lens groups are varied, and that the following conditional expression is satisfied:1.<f2/f3<5.00where f2 and f3 are the focal lengths of the second and third lens groups, respectively.