Six-Element Imaging Lens Aberration Correction
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Solution Overview
Problem
Conventional imaging lenses for compact devices struggle to achieve a low-profile design while providing a wide field of view and high brightness, often facing difficulties in correcting aberrations in the peripheral area of the image.
Innovation Solution
A six-element imaging lens configuration with specific refractive power arrangements and aspheric surfaces, including a double-sided aspheric aberration correction optical element with virtually no refractive power, is used to correct aberrations without altering the overall focal length, ensuring low-profileness and improved peripheral area performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional five-lens configuration is used to achieve high brightness with F-value of about 2.0 to 2.5, then brightness is improved, but the total track length becomes longer than the diagonal length of the effective imaging plane, making it difficult to achieve low-profile design
Solution Approach 1:
The imaging lens is divided into three distinct optical element groups (first group with positive refractive power, second group with positive refractive power, third group with negative refractive power) instead of using a conventional five-lens configuration. This segmentation allows for more flexible arrangement and shorter total track length while maintaining brightness performance with F-value of 2.5 or less
Solution Approach 2:
The patent introduces specific conditional expressions for focal lengths (fLG1, fLG2, fLG3) and their ratios to the overall focal length f, as well as for curvature radii (r5, r6). By optimizing these parameters within defined ranges, the lens achieves both compact size and high brightness without compromising aberration correction
2Area of moving object
If the lens configuration is designed to offer a wide field of view of 70 degrees or more, then field of view is improved, but it becomes difficult to correct aberrations in the peripheral area of the image
Solution Approach 1:
The patent employs aspheric surfaces on multiple lens elements, specifically requiring the fourth lens to have an aspheric surface with at least one pole-change point off the optical axis, and the fifth lens to have an aspheric surface. These curved surfaces effectively correct aberrations in the peripheral area while maintaining a wide field of view of 70 degrees or more
Solution Approach 2:
Different optical elements are assigned specific functions: the first group corrects chromatic aberrations, the second group corrects spherical aberrations, and the third group corrects coma aberrations and controls field curvature. This localized optimization of each element's properties enables comprehensive aberration correction across the entire wide field of view
3Reliability
If more optical elements are added to correct aberrations and provide wide field of view, then imaging performance is improved, but the device complexity and profile increase
Solution Approach 1:
Each optical element group serves multiple functions: the first group with positive refractive power contributes to overall focusing and corrects chromatic aberrations; the second group with positive refractive power corrects spherical aberrations and contributes to focusing; the third group with negative refractive power corrects coma aberrations and controls field curvature. This multi-functionality reduces the need for additional dedicated correction elements
Solution Approach 2:
The patent combines aberration correction functions within three integrated optical element groups rather than using separate dedicated correction lenses. The aspheric surfaces on the fourth and fifth lenses simultaneously correct multiple types of aberrations including spherical, coma, and distortion, reducing overall 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
The solution enables a compact, low-cost imaging lens with an F-value of 2.5 or less and a field of view of 70 degrees or more, effectively correcting various aberrations and maintaining low-profileness, suitable for integration in compact devices like smartphones and mobile terminals.
Implementation Method 1
a first optical element group with positive refractive power including a first lens with positive refractive power having a convex surface on the object side as a first optical element and a second lens with negative refractive power having a concave surface on the image side as a second optical element
Data Source
AI summary
A compact low-profile low-cost imaging lens with an F-value of 2.5 or less and a wide field of view which corrects aberrations properly. Its elements are arranged from an object side: a first positive optical element group including a first positive lens having a convex object-side surface and a second negative lens having a concave image-side surface; a second positive optical element group including a third positive lens having a convex image-side surface; and a third negative optical element group including a fourth negative double-sided aspheric lens having a concave image-side surface and a fifth double-sided aspheric lens having a concave object-side surface. The fourth lens image-side surface has at least one pole-change point off an optical axis. A double-sided aspheric aberration correction optical element with virtually no refractive power is located in an air gap between the first and second optical element groups.