Variable Magnification Optical System Aberration Control
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Solution Overview
Problem
Conventional variable magnification optical systems fail to adequately suppress variations in aberrations during focusing and magnification changes, particularly in photographic and video camera applications.
Innovation Solution
A variable magnification optical system comprising a first lens group and multiple lens groups, where the distance between these groups is varied, and the lens groups include an object side focusing lens group and an image side focusing lens group with distinct movement trajectories, satisfying specific conditional expressions to correct aberrations effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional variable magnification optical systems are used, then the system structure is relatively simple, but the aberration variations during focusing are not adequately suppressed
Solution Approach 1:
The optical system is divided into multiple lens groups (first through fifth lens groups) with distinct functions. The focusing lens group is separated from other lens groups and assigned specific positive refractive power, allowing independent movement control. This segmentation enables precise aberration correction during focusing while maintaining a manageable system structure through functional specialization of each lens group.
Solution Approach 2:
Different lens groups are assigned specific refractive power characteristics tailored to their functions. The focusing lens group has positive refractive power optimized for focusing operations, while other lens groups have different refractive powers suited for magnification control and aberration correction. This local optimization of optical properties enables effective aberration suppression without requiring complete redesign of the entire system.
2Ease of operation
If the focusing lens group is moved during focusing, then the focusing function is achieved, but the aberration variations are not adequately suppressed
Solution Approach 1:
The conditional expressions define specific parameter ranges for the focusing lens group's refractive power relative to the entire optical system. By controlling the parameter (refractive power) within specific bounds (0.05<fF/f<0.15 and -0.50<fF/f1<-0.20), the system achieves effective focusing while suppressing aberration variations. This parameter optimization allows the focusing lens group to move for focusing operations while maintaining aberration consistency throughout the focusing range.
3Manufacturing precision
If multiple lens groups are used with different movement trajectories, then the aberration correction is improved, but the device complexity increases
Solution Approach 1:
The optical system is divided into multiple lens groups (first through fifth lens groups) with distinct functions. The focusing lens group is separated from other lens groups and assigned specific positive refractive power, allowing independent movement control. This segmentation enables precise aberration correction during focusing while maintaining a manageable system structure through functional specialization of each lens group.
Solution Approach 2:
The first lens group serves multiple functions: it contributes to the overall magnification variation and simultaneously helps correct aberrations during focusing operations. By designing the first lens group with negative refractive power and specific focal length relationships, it performs dual roles in both magnification control and aberration suppression, reducing the need for additional dedicated correction elements and simplifying the overall system configuration.
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 correction of aberrations across various focal lengths and distances, ensuring excellent imaging performance from wide angle to telephoto end states and during focusing from infinity to close distances.
Implementation Method 1
a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having positive refractive power, an aperture stop S, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power
Data Source
AI summary
A variable magnification optical system comprising, in order from an object side, a first lens group and a plurality of lens groups; upon varying a magnification, a distance between the first lens group and the plurality of lens groups being varied, and distances between respective lens groups in the plurality of lens groups being varied; the plurality of lens groups comprising an object side focusing lens group which is moved upon carrying out focusing and at least one image side focusing lens group disposed in a more image side than the object side focusing lens group and moved with a trajectory differing from that of the object side focusing lens group, upon carrying out the focusing; andthe predetermined conditional expressions being satisfied, whereby variations in aberrations upon varying magnification from the wide angle end state to the telephoto end state as well as variations in aberrations upon carrying out focusing from an infinite distance object to a close distance object can be suppressed superbly.