Zoom Lens Third Unit Chromatic Aberration Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lenses with a wide angle of view and high zoom ratio face challenges in achieving small size, high magnification, fast zooming operation, and high optical performance due to inadequate refractive power arrangements and configurations, particularly in the third lens unit, which results in under-correction of chromatic aberration at the zoom middle position.
Innovation Solution
A zoom lens configuration comprising a first positive refractive power lens unit that does not move, a second negative refractive power lens unit that moves, a third positive refractive power lens unit that moves, and a fifth positive refractive power lens unit that does not move, with specific conditional expressions governing the refractive powers and movements of these units to optimize performance across the zoom range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the third lens unit consists of a single positive lens or three lenses (positive lens, positive lens, and negative lens) as disclosed in Japanese Patent Application Laid-Open No. 2016-12118, then the zoom lens achieves a wide angle of view and high zoom ratio, but chromatic aberration is under-corrected at the zoom middle position
Solution Approach 1:
The patent applies parameter changes by introducing specific conditional expressions that define the refractive powers and focal lengths of lenses in the third lens unit. By changing the parameters (refractive power arrangements, focal lengths) within defined ranges, the patent achieves both wide angle of view with high zoom ratio and proper chromatic aberration correction at the zoom middle position, resolving the under-correction issue of the prior art
Solution Approach 2:
The patent uses composite material principles by combining multiple lenses with different refractive properties in the third lens unit. Specifically, it combines positive and negative lenses with carefully selected refractive powers and Abbe numbers to create a composite lens system that corrects chromatic aberration while maintaining the required optical performance across the zoom range
2Productivity
If the refractive power arrangements and configurations are not appropriately set in the third lens unit, then the zoom lens structure is simpler, but fast zooming operation and fast response to zooming operation cannot be achieved
Solution Approach 1:
The patent achieves fast zooming operation by optimizing parameters such as the refractive powers of the third lens unit (f3p and f3n), the focal length ratio (f3n/f3), and the Abbe numbers of the lenses. These parameter changes enable the lens unit to move efficiently during zooming while maintaining optical performance, resulting in fast response without excessive structural complexity
3Volume of moving object
If the zoom lens is designed with appropriate refractive power arrangements to achieve small size and high magnification, then optical performance improves, but the complexity of configuring the third lens unit increases
Solution Approach 1:
The patent reduces the volume of the third lens unit while maintaining high magnification by changing key parameters: the focal length ratio (f3n/f3) is constrained within -2.3 to -0.76, and the Abbe number difference (54) is controlled within 35 to 70. These parameter optimizations allow for a more compact lens unit configuration that achieves both small size and high optical performance without excessive complexity
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 proposed configuration enables a zoom lens with a wide angle of view, high magnification, and high optical performance throughout the zoom range while facilitating fast and responsive zooming operations, effectively correcting chromatic aberrations and maintaining a compact size.
Implementation Method 1
the third lens unit consists of, in order from the object side to the image side, a positive lens, a positive lens, and a negative lens, and conditional expressions are satisfied... νd3p is an average of Abbe numbers of the positive lenses in the third lens unit, and νd3n is an Abbe number of the negative lens in the third lens unit
Data Source
AI summary
A zoom lens includes, in order from the object side, a positive first lens unit not moving for zooming, a negative second lens unit moving for zooming, positive third and fourth lens units moving for zooming, and a positive fifth lens unit not moving for zooming. Intervals between adjacent ones of the first to fifth lens units change for zooming. The third lens unit consists of positive, positive, and negative lenses in order from the object side. Appropriate settings are made to the zoom lens's focal lengths at the wide angle and telephoto ends, the lateral magnifications of the second lens unit at the wide angle and telephoto ends, the focal lengths of the third lens unit and the negative lens in the third lens unit, and the average Abbe number of the positive lenses and the Abbe number of the negative lens in the third lens unit.