Wide-Angle Zoom Lens Aberration Control
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Solution Overview
Problem
Existing wide-angle zoom lenses for single-lens reflex cameras face challenges in achieving hyper wide-angle views greater than 100 degrees and high zoom ratios while maintaining optical quality, as they struggle to balance angle of field, effective aperture, and aberration correction.
Innovation Solution
A wide-angle zoom lens design with four lens groups, including a leading negative refractive power group, a positive refractive power group, a second negative refractive power group, and a trailing positive refractive power group, where the 1st lens group has a front subset and a rear subset of negative refractive power, with specific aspherical surface shapes and displacements to optimize focal lengths and optical power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the front-end lens piece is shaped as spherical to compensate for aberration, then optical quality is improved, but the angle of field cannot be widened beyond 105 degrees
Solution Approach 1:
The patent applies aspherical surfaces instead of spherical surfaces to the front-end lens piece and other lens elements. The aspherical shape allows the lens to achieve both wide angle of field (110 degrees or more) and effective aberration compensation, resolving the contradiction between these two requirements that limited prior art spherical designs could achieve only up to 105 degrees.
Solution Approach 2:
The patent changes the refractive power parameters and curvature parameters of the lens pieces, particularly the front-end lens piece with strong negative refractive power. By optimizing these parameters with aspherical surfaces, the lens achieves wider angle of field while maintaining optical quality, overcoming the limitation of spherical surface designs.
2Length of moving object
If the 1st lens group is downsized to reduce overall lens length, then compactness is improved, but aberration compensation becomes more difficult
Solution Approach 1:
The patent uses aspherical surfaces on the front-end lens piece and other lens elements to achieve effective aberration compensation within a compact lens group structure. The aspherical shape provides the necessary optical correction without requiring increased lens group size, thus maintaining both compactness and optical quality.
Solution Approach 2:
The patent applies different surface shapes (aspherical vs. spherical) to different lens pieces based on their specific optical functions. The front-end lens piece uses aspherical surfaces for aberration compensation, while other pieces may use spherical surfaces, optimizing the balance between compactness and optical performance.
3Adaptability or versatility
If the effective aperture is reduced to widen the angle of field, then the angle of field is improved, but optical quality deteriorates due to increased aberration
Solution Approach 1:
The patent employs aspherical surfaces on key lens pieces, particularly the front-end lens piece with strong negative refractive power, to compensate for aberrations introduced by the reduced effective aperture. This allows the lens to achieve wide angle of field (110 degrees or more) while maintaining optical quality through effective aberration correction.
Solution Approach 2:
The patent uses a composite lens structure with multiple lens pieces of different refractive powers and properties. The combination of aspherical and spherical surfaces, along with carefully selected glass materials, enables the lens to achieve both wide angle of field and high optical quality by balancing the optical characteristics of individual lens elements.
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 design achieves an angle of field as wide as 110 degrees or more, maintains a high zoom ratio, and effectively compensates for aberrations such as astigmatism and curvature of field, while downsizing the lens groups and maintaining a well-balanced optical power.
Implementation Method 1
four groups of lens pieces which are the leading or foremost 1st lens group of negative refractivity closest to an objective field, the succeeding 2nd lens group of positive refractivity, the third lens group of negative refractivity, and the trailing 4th lens group of positive refractivity arranged in this order to move each lens group to vary optical power
Implementation Method 2
the front end lens piece closest to the objective field in the 1st lens group is shaped in negative meniscus lens that has its concave surface faced toward an imaging plane and has the opposite surfaces shaped aspherical... effectively compensates for aberrations such as astigmatism and curvature of field
Implementation Method 3
the 1st lens group includes a front subset of the lens pieces of negative refractive power and a rear subset of negative refractive power the latter one of which is displaced toward the objective field for focusing from an infinitely far point to a near view
Data Source
AI summary
The present invention is directed to wide-angle zoom lenses dedicated to single-lens reflex digital cameras, which attains zoom ratio greater than 2. Such a wide-angle zoom lens has four groups of lens pieces, namely comprising the leading or foremost 1st lens group of negative refractivity closest to an objective field, the succeeding 2nd lens group of positive refractivity, the third lens group of negative refractivity, and the trailing 4th lens group of positive refractivity arranged in this order to move each lens group to vary optical power; and the 1st lens group includes a front subset of the lens pieces of negative refractive power and a rear subset of negative refractive power. The front-end lens piece in the 1st lens group is shaped in negative meniscus lens that has its concave surface faced toward an imaging plane and has the opposite surfaces shaped aspherical. The front and rear subsets of the 1st lens group meet requirements of a focal length as expressed in the following formula:3.5≦|f1b/f1a|≦6.0 where f1a is a focal length of the front subset of the lens pieces in the 1st lens group and f1b is the focal length of the rear subset in the 1st lens group.