Variable-Power Optical System Aberration Correction
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Solution Overview
Problem
Conventional variable magnification optical systems for cameras suffer from insufficient optical performance during focusing, particularly in correcting aberrations and camera shake-induced image displacement.
Innovation Solution
A variable magnification optical system comprising a first lens group with positive refractive power, a focusing lens group moved along the optical axis, and a vibration reducing lens group movable perpendicular to the axis, with varying intervals between lens groups to correct aberrations and maintain optical performance across different focal lengths and camera shake conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional variable magnification optical system is used, then the device complexity is reduced, but the optical performance upon focusing 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, third lens group with positive refractive power, and fourth lens group with negative refractive power). Each lens group is independently movable along the optical axis, allowing separate control of focusing and magnification functions. This segmentation enables optimized optical performance for each function while maintaining overall system coordination.
Solution Approach 2:
The patent implements dynamic movement mechanisms for each lens group along the optical axis. The first and third lens groups move for focusing operations, while the second and fourth lens groups move for magnification variation. This dynamic configuration allows the system to adapt its optical properties continuously across different shooting conditions, achieving both close-distance and distant object focusing capabilities with maintained aberration correction.
2Adaptability or versatility
If lens groups are moved for focusing, then the focusing range is improved, but the aberration correction deteriorates
Solution Approach 1:
The focusing function is segregated to specific lens groups (first and third lens groups with positive refractive power) while magnification control is assigned to other lens groups (second and fourth lens groups with negative refractive power). This functional segmentation ensures that focusing movements do not interfere with aberration correction, as each lens group has a dedicated role that minimizes negative interactions.
Solution Approach 2:
The patent employs conditional expressions that define specific relationships between focal lengths of adjacent lens groups (e.g., f1/(-f2) within 0.3 to 1.5, (-f2)/f3 within 0.5 to 2.0). These parameter constraints ensure that even when lens groups move during focusing, the optical parameters remain within ranges that maintain effective aberration correction. The systematic control of focal length ratios prevents excessive aberration generation during focusing operations.
3Adaptability or versatility
If the optical system is designed for close distance focusing, then the near focusing capability is improved, but the infinite distance performance deteriorates
Solution Approach 1:
The patent implements a dynamic lens group movement system where the first and third lens groups can move independently along the optical axis. For close-distance focusing, these groups move forward to increase optical power; for distant objects, they return to reference positions. This dynamic adjustment maintains optimal optical parameters across the entire focusing range, preventing degradation of infinite distance performance when close focusing is enabled.
Solution Approach 2:
The system maintains balanced focal length relationships between lens groups through conditional expressions (f1/(-f2), (-f2)/f3, f3/(-f4)). These parameter constraints ensure that the optical system preserves its aberration correction characteristics whether focused at infinity or close distances. The coordinated movement and parameter control allow the system to adapt its optical power without sacrificing performance at either focusing extreme.
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 superior optical performance from infinite to close distance focusing and effective correction of image displacement caused by camera shake, ensuring high image quality and stability across varying magnifications.
Implementation Method 1
a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having negative refractive power, in order from an object side along an optical axis
Implementation Method 2
a focusing lens group which is moved along the optical axis for focusing
Implementation Method 3
a vibration reducing lens group that is movable to include a component in a direction perpendicular to the optical axis
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Composing, in order from an object side along the optical axis, a first lens group having positive refractive power, and at least one lens group; upon varying magnification, an interval between the first lens group and a lens group at an image side of the first lens group and adjacent thereto being varied, said first lens group comprising a focusing lens group which is moved along the optical axis for focusing and a vibration reducing lens group that is movable to include a component in a direction perpendicular to the optical axis, thereby providing a an excellent optical performance upon focusing.