Zoom Lens Aberration Correction via Aspherical Negative Lens
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing zoom lens systems face challenges in achieving high optical performance across the entire focal length range, particularly in maintaining good optical performance from the wide-angle to telephoto end states due to difficulties in correcting various aberrations and maintaining a compact, lightweight design while keeping costs low.
Innovation Solution
A zoom lens system comprising a configuration of four lens groups with specific refractive index and Abbe number ranges for each group, including a negative lens with an aspherical surface in the first lens group, and a plastic aspherical lens in the fourth lens group, where the lens groups move along the optical axis to adjust focal lengths, ensuring optimal refractive power distribution and aberration correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a negative-leading type zoom lens system is used to achieve a wide angle of view and compact design, then the minimum shooting distance is short and the focal length can be made short in wide-angle end state, but it becomes difficult to obtain good optical performance over the entire focal length range
Solution Approach 1:
The patent applies local quality by introducing an aspherical surface specifically on the negative lens in the first lens group. This localized modification targets the specific region where aberration correction is most needed in the wide-angle end state, allowing the lens system to maintain compact dimensions while improving optical performance through the specialized surface geometry that corrects spherical and chromatic aberrations
Solution Approach 2:
The patent employs parameter changes by carefully selecting lenses with specific refractive indices (nd1, nd2, nd3) and Abbe numbers (νd1, νd2, νd3) that satisfy defined conditional expressions. This systematic variation of optical parameters enables the lens system to achieve good optical performance across the entire focal length range while maintaining the compact negative-leading configuration
2Device complexity
If conventional lens configurations are used to maintain low manufacturing cost and compact size, then the device complexity is reduced, but the ability to correct various aberrations across the focal length range is insufficient
Solution Approach 1:
The patent introduces an aspherical surface on the negative lens in the first lens group, applying a specialized local property where only one lens element requires complex manufacturing. This localized approach improves overall aberration correction capability while minimizing the increase in device complexity and manufacturing cost, as only a single lens needs the aspherical treatment
Solution Approach 2:
The patent uses composite material principles by combining lenses with different refractive indices and Abbe numbers (nd1 with νd1, nd2 with νd2, nd3 with νd3) in a multi-element configuration. This composite approach allows the system to correct multiple types of aberrations simultaneously while maintaining a relatively simple overall structure that does not significantly increase device 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
This configuration enhances optical performance by effectively correcting chromatic aberration, spherical aberration, and distortion across the focal length range, maintaining a compact and lightweight design while controlling costs, thereby achieving high image quality.
Implementation Method 1
a negative lens, at least one lens in the negative lens includes an aspherical surface
Implementation Method 2
at least one lens in the negative lens includes an aspherical surface, and the negative lens satisfies the following conditional expressions (1) and (2)
Implementation Method 3
upon zooming from a wide-angle end state to a telephoto end state, each lens group moves along an optical axis such that a distance between the first lens group and the second lens group decreases
Data Source
AI summary
Providing a zoom lens system capable of obtaining higher optical performance, an imaging apparatus, and a method for varying a focal length of the zoom lens system. The system includes, in order from an object: a first lens group having negative refractive power; a second lens group having positive refractive power; a third lens group having negative refractive power; and a fourth lens group having positive refractive power. Upon zooming from a wide-angle end state to a telephoto end state, each lens group moves along an optical axis such that a distance between the first and second lens groups decreases, a distance between the second and third lens groups increases, and the distance between the third and fourth lens groups decreases; and the first lens group includes a negative lens, at least one lens in the negative lens includes an aspherical surface, and the negative lens satisfies given conditionals.