Variable Magnification Optical System Aberration Correction
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Solution Overview
Problem
Conventional variable magnification optical systems fail to adequately correct various aberrations, particularly in the wide angle end state, due to insufficient refractive power distribution among lens groups.
Innovation Solution
A variable magnification optical system comprising a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a rear lens group with negative refractive power, where the distances between these groups are varied to achieve focusing and satisfy specific conditional expressions for refractive power ratios and back focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional variable magnification optical system is designed to be small in size with large-sized image pick-up device, then the system can achieve high speed focusing, but various aberrations are not corrected sufficiently
Solution Approach 1:
The optical system is divided into four distinct lens groups (first with positive power, second with negative power, third with positive power, and rear with negative power), each serving specific functions. This segmentation allows independent optimization of each group's characteristics to achieve both fast focusing and superior aberration correction across all focal lengths.
Solution Approach 2:
Each lens group is assigned specific refractive power characteristics and movement ranges tailored to its position in the system. The first lens group has positive power for wide-angle correction, the second has negative power for telephoto correction, and so on. This local differentiation of optical properties enables comprehensive aberration control while maintaining compact dimensions.
2Manufacturing precision
If the refractive power distribution among lens groups is increased to improve aberration correction, then the system size increases, but compact design is compromised
Solution Approach 1:
The distances between lens groups are made variable rather than fixed. During magnification changes, the spacing between adjacent lens groups is dynamically adjusted according to specific conditional expressions. This dynamic configuration allows the system to achieve high aberration correction performance across all focal lengths while maintaining a compact form factor, as the lens groups move closer together when not at extreme focal lengths.
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 superb aberration correction across varying magnifications, from wide angle to telephoto, and enables high-speed focusing, while maintaining a compact size compatible with large-sized imaging devices.
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 rear lens group having negative refractive power
Data Source
AI summary
A variable magnification optical system comprising, in order from an object side, 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 rear lens group having negative refractive power; upon varying a magnification from a wide angle end state to a tele photo end state, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, and a distance between the third lens group and the rear lens group being varied; the third lens group or the rear lens group comprising a focusing lens group which is moved upon carrying out focusing from an infinitely distant object to a closely distant object; and predetermined conditional expression(s) being satisfied, thereby various aberrations being corrected superbly.