Three-Group Optical Layout for Compact Close-Range Aberration Correction
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Solution Overview
Problem
Existing optical systems are not sufficiently miniaturized for close-range photography and lack sufficient aberration correction, especially in Japanese patents 5749629 and 2021-173847, due to large total lengths and focal lengths.
Innovation Solution
An optical system with a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having negative refractive power, where the second lens group moves during focusing while the first and third lens groups are fixed, with specific ratios and configurations to ensure miniaturization and aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the total length and focal length of the optical system are reduced for miniaturization, then the device size is reduced, but the aberration correction capability deteriorates
Solution Approach 1:
The optical system is divided into three lens groups with different refractive power signs (positive, negative, negative), where each group contributes differently to aberration correction. This segmentation allows the system to maintain compact size while distributing aberration correction functions across multiple groups, resolving the contradiction between miniaturization and aberration correction capability
Solution Approach 2:
The second lens group is designed with specific negative refractive power and is positioned to move during focusing, creating local optical characteristics that correct aberrations. This localized design approach enables effective aberration correction in specific regions of the optical path without requiring the entire system to be large, thus resolving the contradiction between compact size and aberration correction
2Reliability
If the second lens group is designed with specific negative refractive power and movement capability for aberration correction, then the aberration correction is improved, but the mechanical load and actuator requirements increase
Solution Approach 1:
Only the second lens group with negative refractive power is designed to move during focusing, while the first and third lens groups remain fixed. This partial action approach concentrates the aberration correction function in a single moving group, reducing the mechanical load on actuators compared to moving multiple groups, while still achieving effective aberration correction
Solution Approach 2:
The refractive power signs of the three lens groups are specifically configured as positive, negative, and negative respectively, with the second group having optimized negative power. This parameter optimization allows the moving second group to achieve effective aberration correction with reduced movement distance and force requirements, resolving the contradiction between correction performance and mechanical load
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 miniaturization and effective aberration correction across various focus distances, enabling high-performance close-range photography with reduced mechanical load and actuator requirements.
Implementation Method 1
a first lens group having a positive refractive power, a second lens group having a negative refractive power and a third lens group having a negative refractive power, sequentially arranged from an object side to an image side
Data Source
AI summary
An optical system includes: a first lens group having a positive refractive power, a second lens group having a negative refractive power and a third lens group having a negative refractive power, sequentially arranged from an object side, when focusing, the second lens group moves along an optical axis, the first lens group and the third lens group are fixed relative to the imaging plane; when a distance from a face closest to the object side to a face closest to an image side of the second lens group is OAL2, and a distance from a face closest to the object side of the entire optical system to the imaging plane is OAL, it is satisfied that: 0.06≤OAL2/OAL.