Zoom Lens Aberration Control via Five-Group Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lens systems for digital single-lens reflex cameras face challenges in achieving favorable optical quality over the entire focal length range due to inadequate refractive power balance and increased aberration fluctuations during zooming.
Innovation Solution
A zoom lens system comprising a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group, where at least the first, third, and fifth lens groups move along the optical axis during zooming, with specific conditions (1) 0.52 < (m345t/m345w)/(ft/fw) < 0.70 and (m2t/m2w)/(ft/fw) < 0.4, ensuring optimal refractive power distribution and aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refractive power of a lens group that takes the major burden of the zooming operation is increased, then a high zoom ratio can be achieved with a predetermined movement amount, but fluctuations in aberrations increase during zooming
Solution Approach 1:
The zoom lens system divides the zooming function across five lens groups (G1-G5) with alternating positive and negative refractive powers. Each lens group contributes to the overall zooming operation, distributing the burden rather than relying on a single high-power group. This segmentation allows achieving high zoom ratios while controlling aberration fluctuations through coordinated movement of multiple groups with balanced refractive powers.
Solution Approach 2:
The patent specifies precise refractive power ratios between lens groups (|f2/fw| between 0.25-0.45, |f4/fw| between 0.15-0.30) and defines movement characteristics during zooming. By carefully controlling these parameters and the movement amounts of each lens group, the system achieves high zoom ratios while maintaining stable aberration characteristics throughout the zoom range.
2Adaptability or versatility
If a zoom lens system is configured of five lens groups, then additional freedom in regard to the movement of the lens groups can be obtained, but device complexity increases
Solution Approach 1:
The five-lens-group configuration segments the optical system into distinct functional units (G1: positive, G2: negative, G3: positive, G4: negative, G5: positive). This segmentation provides movement freedom for aberration correction while the alternating sign pattern and focal length relationships maintain overall system simplicity and predictability.
Solution Approach 2:
Each lens group serves multiple functions: G1 and G3 contribute to both zooming and aberration correction, while G2 and G4 provide negative power balance and distortion control. G5 serves as both a zooming element and the final imaging group. This multi-functionality reduces the need for additional dedicated correction groups, managing complexity.
3Adaptability or versatility
If the refractive power balance of lens groups is not appropriately determined, then a high zoom ratio can be achieved, but favorable optical quality over the entire focal length range cannot be achieved
Solution Approach 1:
The patent establishes specific parameter ranges for refractive power balance: |f2/fw| between 0.25-0.45 and |f4/fw| between 0.15-0.30, where fw is the focal length at the wide-angle end. These parameter constraints ensure that lens groups with higher zooming burden maintain appropriate power relationships, achieving both high zoom ratios and favorable optical quality across the entire focal length range.
Solution Approach 2:
Different lens groups are assigned specific refractive power characteristics tailored to their roles: G1 and G3 (positive groups) handle convergence and zooming, while G2 and G4 (negative groups) provide divergence and distortion control. G5 (positive group) ensures proper image formation. This local optimization of refractive power quality in each group contributes to overall optical quality while maintaining high zoom capability.
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 a favorable optical quality over the entire focal length range by suppressing aberration fluctuations and simplifying the lens frame structure, reducing costs and manufacturing complexity.
Implementation Method 1
a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group, in that order from the object side
Data Source
AI summary
A zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group having a plurality of lens elements. During zooming from the short to long focal length extremities, at least the first, third and fifth lens groups move in an optical axis direction. A surface closest to the image side of the zoom lens system is a concave surface facing the image side. The following condition (1) is satisfied:0.52<(m345t/m345w)/(ft/fw)<0.70 (1),wherein m345w and m345t designate, at the short and long focal length extremities, respectively, the combined lateral magnification of the third, fourth and fifth lens groups when focused on an object at infinity; and fw and ft designate the focal length of the zoom lens system at the short and long focal length extremities, respectively.