Variable Magnification Optical System for Compact Small-F-Number Zooming
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Solution Overview
Problem
There is a demand for a variable magnification optical system that is reduced in size, has a small F-number across the entire magnification range, and maintains high optical performance.
Innovation Solution
A variable magnification optical system comprising a configuration of lens groups with specific refractive powers and spacings, including a first lens group with positive and negative lenses, an intermediate group, and a final lens group, where spacings between groups change during magnification, with an aperture stop positioned between certain lens groups to facilitate size reduction and high optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the optical system is reduced in size, then the compactness is improved, but the F-number increases and optical performance deteriorates
Solution Approach 1:
The optical system is divided into multiple lens groups (first lens group with positive refractive power, second lens group with negative refractive power, intermediate group, and final lens group) that can be independently positioned and adjusted. This segmentation allows each group to contribute to size reduction while maintaining a small F-number through coordinated spacing changes during magnification variation.
Solution Approach 2:
The patent employs dynamic spacing adjustments between lens groups during magnification changes. The distances between the first lens group and second lens group, between the second lens group and intermediate group, and between the intermediate group and final lens group are all variable, allowing the system to optimize both compactness and F-number at different zoom positions.
2Volume of moving object
If the optical system is reduced in size, then the compactness is improved, but the optical performance deteriorates
Solution Approach 1:
The patent applies different refractive power characteristics to different lens groups and positions. The first lens group has positive refractive power with specific lens configurations, the second lens group has negative refractive power, and the final lens group has refractive power optimized for compactness. This local optimization of optical properties enables size reduction while maintaining high optical performance across the entire magnification range.
3Illumination intensity
If the F-number is reduced, then the illumination intensity is improved, but the system complexity increases
Solution Approach 1:
The intermediate group serves multiple functions: it acts as a spacing adjustment mechanism between lens groups, contributes to the overall refractive power distribution, and facilitates both magnification variation and focusing operations. This multi-functionality reduces the need for additional separate components, thereby managing system complexity while achieving a small F-number.
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 a compact design with consistent brightness and improved optical performance throughout the zoom range, suppressing aberrations and facilitating fast focusing.
Implementation Method 1
a first lens group having a positive refractive power, a second lens group having a negative refractive power, an intermediate group, and a final lens group having a refractive power
Data Source
AI summary
A variable magnification optical system consists of, in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an intermediate group, and a final lens group having a refractive power. The intermediate group consists of one or more and five or fewer lens groups. An aperture stop is disposed between a lens surface of the second lens group closest to the image side and a lens surface of the final lens group closest to the object side. The first lens group includes, in consecutive order from a position closest to the object side to an image side, a negative lens, and a positive lens. The variable magnification optical system satisfies a predetermined conditional expression.