Wide Angle Lens Aberration Control via Segmented Groups
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Solution Overview
Problem
Retro-focus type wide angle lenses face significant aberration issues due to variations in the extra-axial beam height during focusing, leading to increased aberrations and challenges in maintaining image quality while minimizing size and cost.
Innovation Solution
A wide angle lens system with a first lens group having negative refractive power and a second lens group with positive refractive power, featuring specific lens configurations and arrangements, including meniscus and biconvex/concave lenses, to optimize focal lengths and distances, and incorporating aspherical surfaces to control aberrations, while allowing for compact and cost-effective design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a retro-focus type lens structure is used to achieve a long back focal length, then the lens can be used in applications requiring space between the lens and image sensor, but the height of extra-axial beams changes significantly during focusing operations, causing increased aberrations and degraded image quality
Solution Approach 1:
The lens system is divided into multiple lens groups (first lens group with negative refractive power, second lens group with positive refractive power, and third lens group) that can move independently during focusing operations. This segmentation allows each group to contribute differently to aberration correction while maintaining the retro-focus structure's long back focal length advantage.
Solution Approach 2:
Different regions of the lens system are designed with specific optical properties to address local aberration issues. The first lens group uses a meniscus lens with specific curvature ratios to control spherical aberration, while the second lens group uses a biconcave lens to control coma and astigmatism. Each lens group's refractive power and geometry are optimized for its specific role in the overall aberration correction scheme.
2Length of stationary object
If the retro-focus type lens is designed to maintain a long back focal length, then the structural requirements are met, but the lens system becomes more complex and difficult to manufacture with precise aberration correction
Solution Approach 1:
The patent specifies precise parameter ranges for lens curvatures, thicknesses, and spacing to achieve optimal aberration correction. For example, the ratio of radii of curvature for specific lens surfaces is constrained within defined ranges, and the refractive powers of different lens groups are carefully balanced. These parameter optimizations make the design more manufacturable by providing clear fabrication targets while maintaining the long back focal length.
3Reliability
If the lens system is designed to correct aberrations during focusing, then image quality is maintained, but the number of lens elements and system complexity increase
Solution Approach 1:
The lens groups are designed to perform multiple functions simultaneously. The first lens group with negative refractive power not only contributes to the retro-focus structure but also corrects spherical aberration and controls the chief ray angles. The second lens group with positive refractive power serves both as a focusing element and an aberration corrector for coma and astigmatism. This multi-functionality reduces the need for additional dedicated correction 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 solution achieves improved aberration correction and compact size, maintaining high image quality with reduced complexity and cost, enabling efficient focusing operations and minimizing optical performance degradation.
Implementation Method 1
a first lens group having a negative refractive power and a second lens group having a positive refractive power arranged from an object side
Data Source
AI summary
A wide angle lens system includes a first lens group having a negative refractive power and a second lens group having a positive refractive power arranged from an object side. The first lens group includes a first lens of a meniscus shape having a convex surface toward the object side, a second lens having a concave surface toward the object side, and a third lens having a convex surface toward the object side, and the second lens group includes a fourth lens having a convex surface toward the object side, a fifth lens having a concave surface toward the object side, and a sixth lens of a meniscus shape having a concave surface toward the object side. A photographing apparatus includes the wide angle lens system.