Imaging Lens with Segmented Focus Groups for High Magnification
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Solution Overview
Problem
Existing imaging lenses face challenges in achieving high maximum imaging magnification, small F number, and reduced weight of focus lens groups while suppressing aberration fluctuations during focusing, particularly in macro lenses.
Innovation Solution
The design incorporates a lens system with a first lens group having positive refractive power, a second lens group with a negative and positive focus lens group, and a third lens group, where the first and second focus lens groups move relative to each other to maintain high optical performance, and the third lens group provides vibration-proof image blur correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the maximum imaging magnification is increased to achieve high macro performance, then the imaging capability is improved, but the weight of the focus lens group increases
Solution Approach 1:
The focus lens group is divided into two separate focus lens groups (first and second) with different refractive powers. This segmentation allows each group to be optimized independently for specific functions, reducing the overall weight while maintaining high imaging magnification capability through coordinated movement of the divided groups.
Solution Approach 2:
The patent changes the refractive power parameters of the focus lens groups, with the first having negative refractive power and the second having positive refractive power. This parameter change enables more efficient optical design that achieves high magnification with lighter lens groups compared to conventional single-group designs.
2Illumination intensity
If the F number is reduced to improve light gathering capability, then the imaging performance is improved, but the aberration control becomes more difficult
Solution Approach 1:
Different regions of the optical system are assigned different functional qualities: the first focus lens group with negative refractive power addresses specific aberrations, while the second focus lens group with positive refractive power handles other aberration components. This local quality differentiation enables effective aberration control even with a small F number for improved light gathering.
Solution Approach 2:
The optical system uses a composite structure combining lens groups with different refractive powers (negative and positive) and different material properties. This composite approach allows the system to achieve both small F number for high illumination and effective aberration control through the complementary characteristics of the combined lens groups.
3Speed
If the weight of the focus lens group is reduced to increase auto-focusing speed, then the focusing performance is improved, but the aberration fluctuation increases
Solution Approach 1:
Dividing the focus lens group into two lighter sub-groups reduces the overall moving mass, increasing auto-focusing speed. The segmented design allows each subgroup to be optimized for minimal weight while the coordinated movement of both groups maintains aberration control, preventing excessive aberration fluctuation during focusing.
Solution Approach 2:
By changing the refractive power parameters of the focus lens groups (negative for the first, positive for the second), the patent achieves a configuration where lighter lens groups can be used without causing excessive aberration fluctuation, thus improving auto-focusing speed while maintaining optical quality.
4Reliability
If the number of lenses in the focus lens group is increased to correct aberrations, then the optical performance is improved, but the weight increases
Solution Approach 1:
Instead of increasing the number of lenses, the patent changes the refractive power parameters of the lenses in the focus groups. The first focus lens group has negative refractive power and the second has positive refractive power, allowing effective aberration correction with a minimal number of lenses, thus reducing weight while maintaining optical performance.
Solution Approach 2:
Each focus lens group is assigned a specific refractive power sign (negative for first, positive for second) to address specific aberration types. This local quality assignment enables efficient aberration correction with fewer lenses compared to a conventional single-group design, reducing the weight of the moving focus components.
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 achieves high maximum imaging magnification, a small F number, reduced weight of focus lens groups, and effective suppression of aberration fluctuations, enhancing overall optical performance and auto-focusing speed.
Implementation Method 1
During focusing from an object at infinity to a close-range object, the first focus lens group and the second focus lens group are moved respectively by changing a mutual spacing therebetween in a direction of an optical axis
Implementation Method 2
a first lens group that has a positive refractive power
Implementation Method 3
a first focus lens group, which is disposed to be closest to the object side of the second lens group and has a negative refractive power
Implementation Method 4
a second focus lens group which is disposed to be closest to an image side of the second lens group and has a positive refractive power
Data Source
AI summary
The imaging lens consists of, in order from the object side, a first lens group having a positive refractive power, a second lens group, and a third lens group. In the second lens group, a first focus lens group having a negative refractive power is disposed to be closest to the object side, and a second focus lens group having a positive refractive power is disposed to be closest to the image side. During focusing, only the first and second focus lens groups move by changing the mutual spacing therebetween. The first lens group has two positive lenses and one negative lens. The first focus lens group consists of two or less lenses including a negative lens. Predetermined conditional expressions are satisfied.