Compact Wide-Angle Imaging Lens Aberration Correction
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Solution Overview
Problem
Conventional wide-angle imaging lenses for large imaging devices face challenges in achieving compactness while maintaining a wide angle of view and high image quality, as they tend to become long and struggle with aberration correction due to asymmetrical lens groups and negative power configurations.
Innovation Solution
The design incorporates a first lens group with negative or positive refractive power, an aperture stop, and a second lens group with a positive refractive power, including a negative lens and an aspherical lens with a concave surface, satisfying specific conditional formulae to balance aberration correction and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a retro focus type lens with a leading negative lens group is used to obtain a long back focus, then the back focus amount is improved, but the total length of the lens becomes long
Solution Approach 1:
The lens is divided into multiple lens groups (first lens group with negative refractive power, second lens group with positive refractive power, third lens group with negative refractive power) separated by aperture stops. This segmentation allows independent optimization of each group's function, enabling compact total length while maintaining sufficient back focus through the coordinated design of each segment.
Solution Approach 2:
The patent introduces asymmetrical lens group configurations and utilizes aspherical surfaces to correct aberrations in the compact design. By working in multiple dimensional aspects (aspherical curvature, asymmetrical arrangement), the lens achieves both compactness and adequate back focus without relying solely on traditional retro focus geometry.
2Manufacturing precision
If the lens groups in front of and to the rear of the aperture stop are made asymmetrical to correct aberrations, then the aberration correction is improved, but the design complexity increases
Solution Approach 1:
The patent applies different refractive power characteristics to specific local regions: the first lens group has negative refractive power for wide angle coverage, the second lens group has positive refractive power for focusing, and the third lens group has negative refractive power for aberration correction. This localized optimization achieves superior aberration correction while maintaining manageable design complexity through clear functional zoning.
Solution Approach 2:
The patent employs aspherical surfaces in the lens groups, particularly in the third lens group, to correct aberrations. The aspherical curvature provides enhanced control over light paths and aberration correction compared to spherical surfaces, achieving high manufacturing precision while the standardized aspherical design reduces overall complexity.
3Length of stationary object
If a negative power lens is placed at the front end to obtain large back focus, then the back focus amount is improved, but field curvature and Petzval sum increase in the negative direction
Solution Approach 1:
The patent combines multiple lens groups with different refractive powers (negative, positive, negative) in a coordinated sequence. The first and third lens groups with negative refractive power are balanced by the second lens group with positive refractive power. This merging of opposing refractive effects allows maintenance of adequate back focus while compensating for the negative field curvature and Petzval sum through the positive power group.
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 allows for a compact, wide-angle imaging lens that effectively corrects spherical aberration, field curvature, and chromatic aberrations, while maintaining a wide angle of view and high image quality, facilitating both miniaturization and performance.
Implementation Method 1
a lens B having a negative refractive power, an aspherical lens surface at least toward the object side, and a concave surface toward the object side
Data Source
AI summary
An imaging lens includes: a first lens group; an aperture stop; and a second lens group having a positive refractive power, in this order from an object side. The first lens group includes a negative first lens provided most toward the object side. The second lens group includes a positive lens, provided most toward an imaging surface, and a negative lens having a concave surface and an aspherical surface at least toward the object side. The following Conditional Formula are satisfied: 0.03<(|Sagsp1|−|Sagas1|)/Re1<0.35; and 1.819≰NdAB wherein Sagsp1 is the sag of a reference spherical surface at the edge of the effective diameter of the object side surface of the negative lens, Sagas1 is the sag of the aspherical surface of the lens, Re1 is the effective diameter of the object side surface of the lens, and NdAB is the average refractive index of the positive lens and the negative lens.