Zoom Optical System With Split Focusing Groups for Aberration Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lenses struggle to effectively correct various aberrations such as curvature of field, spherical aberration, and chromatic aberration, especially when focusing from infinity to a short distance object, due to inadequate movement trajectories and refractive power distribution of lens groups.
Innovation Solution
The zoom optical system is configured with a preceding lens group and a succeeding lens group, where the succeeding lens group includes a first focusing lens group with positive refractive power and a second focusing lens group with negative refractive power, moving along different trajectories during zooming and focusing, and satisfying specific conditional expressions to optimize refractive power ratios and lens movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single focusing lens group is used to move along a trajectory during focusing, then the device complexity is reduced, but the ability to correct various aberrations (curvature of field, spherical aberration, chromatic aberration) deteriorates
Solution Approach 1:
The succeeding lens group is divided into two separate focusing lens groups (first focusing lens group with positive refractive power and second focusing lens group with negative refractive power). Each group moves along a different trajectory during focusing, allowing independent optimization of their respective roles in correcting different types of aberrations while maintaining overall system performance.
Solution Approach 2:
The first focusing lens group and second focusing lens group are assigned different refractive powers and different movement trajectories tailored to their specific functions. The positive refractive power group primarily corrects curvature of field, while the negative refractive power group addresses spherical and chromatic aberrations, with each group's trajectory optimized for its local correction needs.
2Device complexity
If lens groups move along the same trajectory during focusing, then the device complexity is reduced, but the optical performance for short distance focusing deteriorates
Solution Approach 1:
The focusing mechanism is designed to move the first and second focusing lens groups along different dynamic trajectories rather than a static common path. This allows the optical system to adaptively correct aberrations at different object distances, particularly improving performance for short distance focusing while maintaining flexibility in the focusing mechanism.
3Speed
If the refractive power of the focusing lens groups is increased to improve focusing speed, then the focusing speed increases, but the aberration correction capability deteriorates
Solution Approach 1:
The system uses two focusing lens groups with different refractive power signs (positive and negative) moving along different trajectories. This allows optimization of focusing speed through appropriate refractive power selection while simultaneously maintaining aberration correction capability through the complementary roles of the two groups and their differentiated movement paths.
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
This configuration allows for favorable correction of aberrations over the entire zoom range, ensuring high optical performance even when focusing on short distance objects, with reduced lens weight and size for high-speed focusing.
Implementation Method 1
a first focusing lens group having a positive refractive power and a second focusing lens group disposed on an image surface side of the first focusing lens group and having a negative refractive power
Data Source
AI summary
A variable magnification optical system having a front lens group and a rear lens group arranged in order from the object side along an optical axis, the rear lens group comprising a first focusing lens group and a second focusing lens group. When the magnification is changed, the spacing between lens groups adjacent to each other changes, at the time of changing from focusing on an object at infinity to focusing on an object at a short distance, the position of the front lens group is fixed, the first and second focusing lens groups move to the image surface side along different trajectories, and the conditional expression 0.05<(−fF2)/ft<0.50 is satisfied, where fF2 is the focal length of the second focusing lens group, and ft is the focal length of the variable magnification optical system in a telephoto end state.