Four-Element Imaging Lens Assembly Aberration Correction
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Solution Overview
Problem
Conventional imaging lens assemblies for mobile phone cameras are insufficient for high-end applications due to increased demand for compactness and better image quality, as they often require complex manufacturing processes and cannot easily reduce total track length while effectively correcting aberrations.
Innovation Solution
A compact imaging lens assembly with four lens elements, including a first lens with positive refractive power, a second with negative refractive power, a third with either positive or negative refractive power and a concave object-side surface, and a fourth with a concave image-side surface and inflection points, along with an aperture stop placement that optimizes telecentricity and field of view, to correct aberrations and reduce total track length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional three-element lens assembly is used, then the manufacturing process is relatively simple, but the image quality is insufficient for high-resolution sensors and the total track length cannot be reduced effectively
Solution Approach 1:
The lens assembly is divided into four distinct lens elements with specific refractive power configurations (positive, negative, positive, negative) rather than using a conventional three-element design. This segmentation allows for better correction of spherical and chromatic aberrations, improving image quality for high-resolution sensors while maintaining reasonable manufacturing complexity through standardized element designs
Solution Approach 2:
Each lens element is designed with specific local optical properties including particular refractive powers, curvature radii, and thickness ratios. The first lens element has positive refractive power with specific curvature relationships, the second has negative refractive power, and so on. This localized optimization of optical properties enables effective aberration correction while controlling the overall system complexity
2Manufacturing precision
If more lens elements are added to correct aberrations, then image quality improves, but the total track length increases and compactness is reduced
Solution Approach 1:
The patent establishes specific parameter relationships between the four lens elements including refractive power ratios (0.2 < f2/f1 < 0.8), curvature radius relationships (R1/R2, R3/R4), and thickness ratios (0.1 < d1/f < 0.4, 0.05 < d2/f < 0.3). These parameter constraints enable effective aberration correction with only four elements, preventing excessive total track length while improving image quality for high-resolution sensors
Solution Approach 2:
The lens elements are designed with asymmetric surface curvatures and non-uniform thickness distributions. For example, the first lens element has a convex object-side surface with specific curvature radius R1 and a image-side surface with curvature radius R2 where |R1/R2| is controlled within 0.5-2.0. This asymmetric design allows compact positioning of elements while maintaining effective aberration correction capabilities
3Manufacturing precision
If spherical glass lenses are used to correct chromatic aberration, then chromatic aberration is corrected, but the system freedom is curtailed and total track length cannot be reduced easily
Solution Approach 1:
The patent specifies Abbe number relationships between lens elements (20 < V1-V2 < 40, 15 < V3-V4 < 35) to enable chromatic aberration correction through material selection rather than relying solely on spherical lens configurations. This approach provides greater design freedom compared to conventional spherical glass lens assemblies, allowing optimization of total track length while maintaining effective chromatic aberration correction
Solution Approach 2:
The lens assembly uses multiple lens elements with different glass materials having specific Abbe numbers and refractive indices. By combining materials with different dispersive properties (controlled Abbe number differences), the system achieves effective chromatic aberration correction while maintaining design flexibility and controlling total track length, avoiding the constraints of single-material spherical lens designs
4Length of stationary object
If the aperture stop is positioned to emphasize telecentricity, then total track length is reduced, but field of view is limited
Solution Approach 1:
The patent establishes specific parameter relationships including the aperture stop position relative to lens elements and the curvature radius ratios (0.5 < |R1/R2| < 2.0, 0.5 < |R3/R4| < 2.0) that simultaneously enable telecentric design for compact total track length while maintaining adequate field of view. The thickness ratios (0.1 < d1/f < 0.4, 0.05 < d2/f < 0.3) further optimize the balance between telecentricity and field of view, allowing the system to achieve both compactness and sufficient imaging area
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 total track length, and improves image quality by optimizing the placement of lens elements and aperture stops, enhancing photosensitivity and reducing manufacturing complexity.
Implementation Method 1
a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power having a convex image-side surface; a third lens element having a concave object-side surface and a convex image-side surface
Implementation Method 2
at least one of the object-side and image-side surfaces thereof being aspheric; a fourth lens element having a concave image-side surface, at least one of the object-side and image-side surfaces thereof being provided with at least one inflection point
Data Source
AI summary
This invention provides an imaging lens assembly including, in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface; a second lens with negative refractive power having a convex image-side surface; a third lens having a concave object-side surface and a convex image-side surface, at least one of both surfaces thereof being aspheric; a fourth lens having a concave image-side surface, at least one of both surfaces thereof having at least one inflection point; and an aperture stop disposed between an imaged object and the second lens; the on-axis spacing between the first lens and second lens is T12, the focal length of the imaging lens assembly is f, the Abbe number of the first lens and third lens is, V1 and V3, respectively, they satisfy the relations: 0.5<(T12/f)*100<20, 23<V1−V3.