Macro Lens System Aberration Correction via Integral Group Movement
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Solution Overview
Problem
Existing macro lens systems face challenges in correcting aberrations from infinite to closer distances, particularly at higher magnifications, with existing solutions being mechanically unstable, limited in magnification range, or increasing manufacturing costs.
Innovation Solution
A macro lens system comprising a positive first lens group, a diaphragm, and a stationary negative third lens group, with the positive first and second lens groups moving integrally to correct spherical aberration and distortion across the entire magnification range, utilizing a retro-focus type lens system with specific refractive power distributions to maintain mechanical stability and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a floating mechanism with multiple independently movable lens groups is used to correct aberrations from infinite to closer distance, then aberration correction is improved, but device complexity increases and mechanical stability deteriorates
Solution Approach 1:
The lens system is divided into three lens groups (first, second, and third) with specific refractive power distributions. The first lens group has positive refractive power, the second has negative refractive power, and the third has positive refractive power. This segmentation allows each group to contribute differently to aberration correction while maintaining a simpler overall structure compared to traditional floating mechanisms requiring multiple independently movable groups.
Solution Approach 2:
The patent applies specific parameter constraints to control aberrations: 0.5 < f2/f1 < 1.5 and -2.0 < f2/f < -0.5, where f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, and f is the focal length of the entire lens system. By optimizing these parameter relationships, the system achieves effective aberration correction across focusing distances without requiring complex mechanical adjustments.
2Stability of the object's composition
If lens groups are moved integrally to maintain mechanical stability, then mechanical stability is improved, but aberration correction capability deteriorates at higher magnifications
Solution Approach 1:
The patent introduces a diaphragm that can be moved independently between the first and second lens groups. While the first, second, and third lens groups move integrally to maintain mechanical stability, the diaphragm's independent movement allows dynamic adjustment of the optical path and aberration correction. This dynamic element compensates for the static nature of the integrally moving lens groups, enabling effective aberration control at higher magnifications up to 1:1.
3Manufacturing precision
If the entire lens system is formed as retro-focus type to correct aberrations, then aberration correction is improved, but the system becomes mechanically impossible at -1/2 or 1:1 magnification due to collision
Solution Approach 1:
Instead of forming the entire lens system as a retro-focus type, the patent segments the retro-focus configuration to only the first lens group. The first lens group is designed as retro-focus type, while the second and third lens groups have different configurations. This partial retro-focus approach maintains aberration correction benefits while avoiding the mechanical collision issues that would occur if the entire system were retro-focus type at high magnifications.
Solution Approach 2:
The patent optimizes the refractive power distribution across the three lens groups with specific parameter constraints. The second lens group has negative refractive power with focal length ratio f2/f1 between -2.0 and -0.5 relative to the first lens group. This parameter optimization allows the system to achieve aberration correction similar to retro-focus designs while maintaining the mechanical flexibility needed for high magnification operation.
4Manufacturing precision
If the first lens group is formed as retro-focus type to reduce astigmatism fluctuation, then astigmatism correction is improved, but manufacturing cost increases due to difficult centering
Solution Approach 1:
The patent applies retro-focus configuration only to the first lens group rather than the entire system, and combines it with a multi-element structure in the second lens group. This segmented approach achieves astigmatism correction through the coordinated action of multiple lens groups with different configurations, reducing the centering difficulty associated with full retro-focus designs while maintaining effective astigmatism control.
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 solution effectively corrects aberrations, particularly spherical aberration and distortion, from infinite to closer distances, enabling 1:1 magnification while maintaining mechanical stability and reducing manufacturing costs, thus addressing the limitations of prior art.
Implementation Method 1
the positive first lens group and the positive second lens group integrally move toward the object... to correct spherical aberration and distortion
Implementation Method 2
A macro lens system comprising a positive first lens group, a diaphragm, and a stationary negative third lens group... with the positive first and second lens groups moving integrally
Data Source
AI summary
A macro lens system includes a positive first lens group, a diaphragm, a positive second lens group, and a negative third lens group. Upon focusing from an object at an infinite distance to an object at a closer distance, the positive first lens group and the positive second lens group integrally move toward the object without changing a distance therebetween with respect to the negative third lens group which is stationary with respect to an imaging plane in a camera body. The positive first lens group includes a negative first lens sub-lens group and a positive second sub-lens group which are divided at a maximum distance between lens elements in the positive first lens group. The macro lens system satisfies specified conditions.