Four-Lens Optical Assembly Aberration Correction
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Solution Overview
Problem
Conventional compact imaging lens assemblies, such as those with three or four lens elements, fail to meet the demand for high-end image quality due to issues like aberration and increased total track length, limiting their effectiveness in portable electronic devices.
Innovation Solution
An optical lens assembly comprising four lens elements with specific refractive powers and surface curvatures, including a first lens with positive refractive power, a second with negative refractive power, a third with refractive power, and a fourth made of plastic with negative refractive power, optimized with aspheric surfaces and carefully controlled axial distances and curvature radii to reduce aberrations and total track length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional three-lens structure is adopted, then the device complexity is reduced, but the image quality deteriorates due to insufficient aberration correction
Solution Approach 1:
The patent divides the optical system into four distinct lens elements instead of three, with each element having specific refractive power and surface curvature characteristics. This segmentation allows for more granular control over aberration correction while maintaining a compact overall structure suitable for portable devices.
Solution Approach 2:
The patent applies different surface configurations to different regions of the lens elements. Specifically, the first lens element has a convex object-side surface at its paraxial region, the second has a concave object-side surface at its paraxial region, and the fourth has a concave object-side surface at its paraxial region. These localized surface quality variations enable precise aberration correction in different field regions.
2Manufacturing precision
If a four-lens assembly is used, then the image quality improves, but the total track length increases
Solution Approach 1:
The patent carefully controls specific parameter relationships to optimize the balance between image quality and compactness. The conditions 1.4523/CT30.151/R21r4/T23≦1.02 and 0.701≦T23/CT30.331/R24/Dr1r4 establish precise relationships between axial distances (T23, Dr1r4), central thickness (CT3), and curvature radii (R21, R24). These parameter constraints ensure that the four-lens assembly achieves superior aberration correction while maintaining a compact total track length suitable for portable electronic devices.
3Length of moving object
If the third lens element has positive refractive power to reduce total track length, then the compactness improves, but the image quality deteriorates due to increased aberration
Solution Approach 1:
The patent employs a composite lens structure where the third lens element combines both concave and convex surface characteristics. Specifically, it has a concave object-side surface at its paraxial region and a convex image-side surface at its paraxial region. This composite surface configuration allows the third element to contribute to both compactness (by enabling shorter axial distances) and aberration control (through its dual surface curvature), resolving the contradiction between size reduction and image quality maintenance.
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 enhances image quality by effectively correcting aberrations, reducing the total track length, and improving the compactness of the lens assembly, thereby meeting the demands for better image quality in portable electronic devices.
Implementation Method 1
a fourth lens element made of plastic with negative refractive power comprising a concave object-side surface at a paraxial region and a concave image-side surface at a paraxial region. The image-side surface of the fourth lens element is convex at a peripheral region. Both of the object-side surface and the image-side surface of the fourth lens element are aspheric.
Implementation Method 2
an optical lens assembly for image taking comprises, in order from an object side to an image side, a first lens element with positive refractive power, a second lens element with negative refractive power, a third lens element with refractive power, and a fourth lens element made of plastic with negative refractive power
Data Source
AI summary
An optical lens assembly for image taking includes a first lens element, a second lens element, a third lens element and a fourth lens element. The first lens element with positive refractive power includes a convex object-side surface at a paraxial region. The second lens element with negative refractive power includes a concave object-side surface at a paraxial region. The third lens element with refractive power includes a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region. The fourth lens element made of plastic with negative refractive power includes a concave object-side surface at a paraxial region and an image-side surface. Both of the object-side surface and the image-side surface of the fourth lens element are aspheric, and the image-side surface of the fourth lens element is concave at a paraxial region and convex at a peripheral region.