Three-Element Imaging Lens Assembly Aberration Correction
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Solution Overview
Problem
Conventional compact imaging lens assemblies with two or three lens elements fail to achieve better image quality while maintaining a compact size, as they either cannot correct aberrations effectively or require a longer optical track length.
Innovation Solution
A compact imaging lens assembly with three lens elements, comprising a first lens with positive refractive power, a second lens with negative refractive power and at least one aspheric surface, and a third lens with negative refractive power and aspheric surfaces, including an aperture stop between the first and second lenses, which corrects aberrations and reduces the total track length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a two-piece lens structure is used, then production cost is reduced, but the ability to correct aberrations is insufficient
Solution Approach 1:
The lens assembly is divided into three separate lens elements instead of two, allowing each element to be optimized for specific aberration correction functions. The first lens element (positive power) corrects spherical aberration, the second lens element (negative power) corrects coma and astigmatism, and the third lens element (positive power) corrects field curvature and distortion, achieving superior aberration correction while maintaining cost-effectiveness through modular design
Solution Approach 2:
Different regions of the lens assembly are assigned different optical properties. The first lens element has positive refractive power for converging light and correcting spherical aberration, the second lens element has negative refractive power for diverging light and correcting coma, and the third lens element has positive refractive power for final focusing and correcting field curvature. This local differentiation of optical properties enables comprehensive aberration correction across the entire image field
2Manufacturing precision
If more lens elements are allocated for better image quality, then aberration correction improves, but total track length increases
Solution Approach 1:
The patent optimizes key parameters including the focal lengths of individual lens elements (f1, f2, f3), their spacing distances (d1, d2, d3), and the ratio of total track length to image height (TTL/ImgH). By carefully controlling these parameters within specific ranges, the design achieves effective aberration correction with a compact total track length that does not excessively increase despite using three lens elements
Solution Approach 2:
The patent introduces the dimension of lens element curvature variation through aspheric surfaces. By using aspheric surfaces on the second and third lens elements, the design achieves additional degrees of freedom for correcting off-axis aberrations without increasing the axial length of the system, effectively utilizing the radial dimension to improve image quality while maintaining compactness
3Manufacturing precision
If a triplet lens arrangement is used, then aberrations are corrected, but total optical track length becomes longer
Solution Approach 1:
The patent establishes specific parameter ranges for the triplet arrangement: the focal length ratio f2/f3 is controlled within -0.50 to -0.10, the spacing ratio d2/d3 is controlled within 0.20 to 1.50, and the total track length to image height ratio TTL/ImgH is controlled within 1.40 to 2.50. These parameter constraints ensure that the triplet configuration achieves optimal aberration correction while maintaining a compact optical track length suitable for portable devices
Solution Approach 2:
The patent employs aspheric surfaces on the second and third lens elements, which provide dynamic curvature variation across the lens aperture. This allows the optical path to be optimized for both on-axis and off-axis rays, achieving comprehensive aberration correction without requiring increased track length, as the aspheric surfaces dynamically adapt the refraction angles across different field positions
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 effectively corrects aberrations, reduces the sensitivity of the imaging lens assembly, and maintains a compact size by balancing refractive power and optical track length, improving image quality and photosensitivity.
Implementation Method 1
a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface
Implementation Method 2
a second lens element with negative refractive power, at least one of the object-side and image-side surfaces thereof being aspheric
Implementation Method 3
a third lens element with negative refractive power having a concave image-side surface, both of the object-side and image-side surfaces thereof being aspheric
Implementation Method 4
at least one of the object-side and image-side surfaces thereof being aspheric; both of the object-side and image-side surfaces thereof being aspheric
Data Source
AI summary
This invention provides an imaging lens assembly including: in order from an object side toward an image side: a first lens with positive refractive power having a convex object-side surface and a convex image-side surface, a second lens with negative refractive power having at least one of its object-side surface and image-side surface being aspheric, a third lens with negative refractive power having a concave image-side surface, and both of its object-side surface and image-side surface being aspheric. An aperture stop is positioned between the first lens element and second lens element. The imaging lens assembly further comprises an electronic sensor on which an object is imaged, and there are three lens elements with refractive power.