Six-Element Aspheric Lens Assembly for Aberration Correction
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Solution Overview
Problem
Conventional compact optical lens systems, particularly those with four-element or five-element structures, fail to meet the increasing demands for higher pixel count, improved image quality, and reduced size in portable electronic devices, as they struggle with aberration, distortion, and limited field of view.
Innovation Solution
An image system lens assembly comprising six elements, with specific refractive powers and surface configurations, including aspheric surfaces, is designed to optimize image quality by adjusting the focal lengths and distances between elements, using plastic or glass materials to enhance flexibility and reduce manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a four-element lens structure is used, then the device complexity is reduced, but the image quality and aberration correction deteriorate
Solution Approach 1:
The patent divides the lens system into six distinct lens elements with specific refractive power distributions. The first lens element has negative refractive power, while the second through sixth elements have positive refractive power. This segmentation allows each element to contribute differently to aberration correction, achieving superior image quality that cannot be obtained with fewer elements.
Solution Approach 2:
The patent applies aspheric surfaces to specific lens elements (first, fourth, and sixth elements) rather than uniformly across all elements. This local application of aspheric design targets specific aberration problems in different regions of the optical path, optimizing image quality where needed most while maintaining manufacturing feasibility.
2Manufacturing precision
If conventional five-element lens structure is used, then the image quality improves, but the field of view cannot be enlarged and total track length cannot be reduced
Solution Approach 1:
The patent specifies precise parameter relationships to optimize performance: the ratio of the focal length of the first lens element to the total focal length is controlled within -0.8 to -0.2, and the ratio of the second lens element's focal length to the total focal length is controlled within 0.6 to 1.4. These parameter constraints enable the system to achieve a wide field of view while maintaining compact dimensions and high image quality.
Solution Approach 2:
The patent employs aspheric surfaces on the first, fourth, and sixth lens elements, which introduce additional degrees of freedom in the optical design. The aspheric coefficients allow control of light rays in different zones of the lens, enabling enlargement of the field of view without proportionally increasing the total track length.
3Manufacturing precision
If conventional five-element lens structure is used, then the image quality improves, but the aberration and distortion cannot be eliminated
Solution Approach 1:
The patent strategically places lens elements with negative refractive power (first element) at the front of the system to pre-correct certain types of aberrations before light enters the positive power elements. The negative refractive power elements introduce opposite aberrations that cancel out the harmful effects generated by subsequent positive power elements, effectively eliminating distortion and chromatic aberration.
Solution Approach 2:
The patent combines different lens element materials with varying refractive indices and dispersion properties. The first lens element uses a material with specific Abbe number characteristics to correct chromatic aberration, while subsequent elements use materials optimized for their specific functions. This composite material approach allows simultaneous correction of multiple aberration types that cannot be addressed with a single material type.
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 provides superior aberration correction and image quality, enabling a larger field of view while maintaining a compact size, suitable for applications in electronic image systems like digital cameras and portable devices.
Implementation Method 1
The first lens element with negative refractive power has a convex object-side surface and a concave image-side surface. The second lens element has positive refractive power. The third lens element has refractive power. The fourth lens element with negative refractive power has a concave object-side surface and a convex image-side surface.
Implementation Method 2
The fifth lens element with positive refractive power is made of plastic material, wherein at least one of an object-side surface and an image-side surface of the fifth lens element is aspheric. The sixth lens element with refractive power is made of plastic material and has a convex object-side surface and a concave image-side surface, wherein the image-side surface of the sixth lens element changes from concave at a paraxial region to convex at a peripheral region, and at least one of the object-side surface and the image-side surface of the sixth lens element is aspheric.
Data Source
AI summary
An image system lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with negative refractive power has a convex object-side surface and a concave image-side surface. The second lens element has positive refractive power. The third lens element has refractive power. The fourth lens element with negative refractive power has a concave object-side surface and a convex image-side surface. The plastic fifth lens element with positive refractive power has at least one aspheric surface. The plastic sixth lens element with refractive power has a convex object-side surface and a concave image-side surface, and has at least one aspheric surface, wherein the image-side surface thereof changes from concave at a paraxial region to convex at a peripheral region.