Aspheric Plastic Lens System for Aberration Correction
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Solution Overview
Problem
Conventional imaging lens systems for portable devices, such as camera phones and compact digital cameras, face challenges in achieving a compact, low-cost, and high-performance design due to limitations in correcting spherical and astigmatic aberrations, especially at smaller F-numbers and wider angles, leading to increased length and weight, and high manufacturing sensitivity.
Innovation Solution
A compact imaging lens system comprising a first positive aspheric meniscus lens element with a concave surface facing the object side and a second negative aspheric lens element with a concave surface facing the image side, both made of plastic, with specific focal length and curvature radius ratios to minimize aberrations and overall length, while reducing tolerance sensitivity and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional spherical glass lenses are used, then material availability and ease of manufacturing are improved, but spherical aberration and astigmatic aberration correction deteriorates
Solution Approach 1:
The patent changes the shape parameter of the lens surface from spherical to aspheric, introducing an aspheric coefficient k in the aspheric surface equation. This parameter change enables the lens to correct spherical and astigmatic aberrations while maintaining manufacturing feasibility through molding processes.
Solution Approach 2:
The patent employs plastic materials for the lens elements, combining aspheric surface geometry with plastic material properties. This composite approach (aspheric shape + plastic material) achieves superior aberration correction compared to traditional spherical glass lenses, while maintaining cost-effectiveness and manufacturing ease.
2Manufacturing precision
If aspheric plastic lenses or aspheric molded glass lenses are used, then aberration correction is improved, but lens system length increases
Solution Approach 1:
The patent merges multiple lens elements into a compact configuration where the aspheric surfaces of the plastic lens elements work together in a integrated structure. The first aspheric plastic lens element and second aspheric plastic lens element are positioned to work in unison, correcting aberrations while minimizing the overall length of the lens system.
Solution Approach 2:
The patent utilizes aspheric curvature surfaces instead of spherical surfaces. The aspheric surfaces with specific conic coefficients provide superior aberration correction in a more compact form factor, reducing the lens system length while maintaining optical performance.
3Manufacturing precision
If one glass lens element and two plastic lens elements are used, then aberration compensation is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies aspheric surface treatment specifically to the plastic lens elements where it is most needed for aberration correction. By localizing the complex aspheric geometry to the plastic components rather than requiring a glass element, the design simplifies manufacturing while maintaining optical performance.
Solution Approach 2:
The patent replaces expensive glass lens elements with cost-effective plastic lens elements that can be manufactured through molding processes. This substitution maintains the necessary aberration compensation functionality while significantly reducing manufacturing cost and complexity.
4Illumination intensity
If smaller F-number and larger wide angle of field are used, then light gathering capability is improved, but spherical aberration and astigmatic aberration worsen
Solution Approach 1:
The patent changes the surface geometry parameter from spherical to aspheric, introducing the aspheric coefficient k in the aspheric surface equation. This parameter change enables the lens to correct spherical and astigmatic aberrations while maintaining the ability to gather light at smaller F-numbers and wider angles.
Solution Approach 2:
The patent employs aspheric curvature surfaces that are specifically designed to control light rays at oblique angles. The aspheric surfaces provide progressive curvature that effectively manages aberrations in wide-angle, low-F-number applications, maintaining both light gathering capability and optical precision.
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 system effectively corrects aberrations, reduces overall length, and lowers production costs, enabling mass production of compact, high-performance imaging lenses suitable for portable devices.
Implementation Method 1
a first positive lens element on the object side and a second negative lens element on the image side... Both the first and second lens elements are aspheric lenses each having at least one aspheric surface
Data Source
AI summary
A compact imaging lens system consists of a first positive aspheric lens element (1) on the object side and a second negative aspheric lens element (2) on the image side. The first lens element is a meniscus lens convex toward the image side, whereby the incident light beam can be diverged by the first concave surface (11) of the first lens element, and thus a wide area of the second convex surface (12) of the first lens element can be illuminated by the divergent light beam. The second negative aspheric lens element is provided mainly for correcting chromatic aberration and off-axis aberration.