Four-Group Zoom Lens Layout for Aberration-Stable High Zoom
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Solution Overview
Problem
Existing zoom lenses face challenges in achieving a high variable magnification ratio, smaller size, and higher image quality while effectively suppressing aberration variation during zooming.
Innovation Solution
A zoom lens configuration with specific refractive power arrangements for lens groups, including a second lens group immovable during zooming, and satisfying conditional expressions for refractive power ratios, allows for a positive lead type configuration that suppresses aberration variation and enables a smaller size and higher image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a positive lead type configuration is used to achieve high variable magnification ratio and small size, then the zoom lens can be compact and lightweight, but aberration variation during zooming is not sufficiently suppressed
Solution Approach 1:
The patent applies parameter changes by establishing specific conditional expressions for the refractive powers of lens groups (0.3 < -f2/fw < 0.7 and 0.5 < f3/fw < 1.5). These parameter constraints optimize the balance between achieving high variable magnification ratio with compact size while suppressing aberration variation during zooming operations.
Solution Approach 2:
The zoom lens is segmented into four distinct lens groups with alternating refractive powers (positive, negative, positive, negative from object side to image plane). This segmentation allows each group to be optimized for specific functions: the first group for overall focusing, the second for aberration correction, the third for magnification control, and the fourth for fine-tuning image quality, thereby resolving the contradiction between compact size and aberration suppression.
2Adaptability or versatility
If lens groups are arranged in positive lead type configuration, then high variable magnification ratio is achieved, but image quality deteriorates due to aberration variation
Solution Approach 1:
The patent uses parameter changes by defining precise ranges for refractive power ratios (0.3 < -f2/fw < 0.7 and 0.5 < f3/fw < 1.5). These parameter optimizations enable the lens to achieve high variable magnification ratio while maintaining consistent image quality across the zoom range by minimizing aberration variation.
Solution Approach 2:
The patent employs asymmetric arrangement of lens groups with alternating refractive powers rather than symmetric configuration. The specific asymmetric positioning and power distribution (positive-negative-positive-negative sequence with constrained power ratios) allows the system to achieve high adaptability for variable magnification while maintaining manufacturing precision and image quality through optimized aberration correction.
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 achieves a high variable magnification ratio with reduced aberration variation, enabling a smaller size and improved image quality across the zoom range.
Implementation Method 1
a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, and a fourth lens group G4 having negative refractive power
Data Source
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AI summary
A zoom lens according to the present disclosure includes a plurality of lens groups, and an aperture stop. The plurality of lens groups includes, in order from a side of an object toward a side of an image plane, 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 fourth lens group having negative refractive power. The second lens group is immovable with respect to the image plane upon zooming, and predetermined conditional expressions are satisfied.