Four-Element Aspheric Lens Aberration Correction
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Solution Overview
Problem
Conventional compact photographing lens assemblies, whether three-element or four-element lens structures, fail to produce high-quality images due to limitations in refractive power distribution, chromatic aberration, and manufacturing complexities, especially in portable electronic devices.
Innovation Solution
A compact photographing optical lens assembly comprising four lens elements with specific refractive powers and aspheric surfaces, including a first lens element with positive refractive power, a second lens element with negative refractive power, a third lens element with positive refractive power, and a fourth lens element with negative refractive power, optimized with precise curvature radii and focal lengths to correct aberrations and reduce total track length, while allowing for easier manufacturing and integration of an aperture stop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a three-element lens structure is adopted, then the device complexity is reduced, but the image quality deteriorates due to insufficient degrees of freedom in correcting aberrations
Solution Approach 1:
The patent divides the lens system into four distinct lens elements with alternating positive and negative refractive powers, allowing independent optimization of each element's parameters to correct various aberrations while maintaining overall system compactness
Solution Approach 2:
The patent employs aspheric surfaces on multiple lens elements, changing the geometric parameters from spherical to aspheric profiles, which provides additional degrees of freedom for correcting spherical aberration, coma, and other monochromatic aberrations, thereby improving image quality without proportionally increasing device complexity
2Manufacturing precision
If glass spherical lens elements are attached to form a doublet lens, then chromatic aberration is eliminated, but the total optical track length increases and manufacturing becomes difficult
Solution Approach 1:
The patent replaces traditional glass spherical doublet lenses with plastic aspheric lens elements, changing both the material parameter (from glass to plastic) and the surface geometry parameter (from spherical to aspheric), which enables effective chromatic aberration correction while reducing total optical track length and simplifying manufacturing
Solution Approach 2:
The patent uses plastic materials for lens elements instead of traditional glass, creating a composite optical system that combines the advantages of plastic (lightweight, moldable, cost-effective) with aspheric surface design to achieve both compact size and high image quality
3Manufacturing precision
If more spherical lenses are allocated, then chromatic aberration is corrected, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the surface parameter from spherical to aspheric on multiple lens elements, which provides additional correction capabilities for both chromatic and monochromatic aberrations without requiring an increase in the number of lens elements, thereby maintaining device simplicity while improving image quality
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 photosensitivity, and maintains a compact size, achieving high image quality and telecentric characteristics suitable for portable electronic products.
Implementation Method 1
The first lens element with positive refractive power has a convex object-side surface. The second lens element with negative refractive power. The third lens element with positive refractive power has a concave object-side surface and a convex image-side surface, wherein the third lens element has at least one aspheric surface. The fourth lens element with negative refractive power having a concave object-side surface, wherein at least one of the object-side surface and the image-side surface of the fourth lens element is aspheric.
Implementation Method 2
A radius of curvature of the object-side surface of the fourth lens element is R7, and a focal length of the photographing optical lens assembly is f, a focal length of the first lens element is f1, and a focal length of the third lens element is f3
Data Source
AI summary
A photographing optical lens assembly includes, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface, a second lens element with negative refractive power, a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface, and a fourth lens element with negative refractive power having a concave object-side surface.