Five-Element Plastic Imaging Lens for Compact Optical Systems
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Solution Overview
Problem
The challenge lies in creating a miniaturized imaging lens with good optical performance while maintaining a shorter overall length, which is more complex than traditional lenses due to material properties and assembly yield rate considerations in portable electronic devices.
Innovation Solution
The design comprises a specific arrangement of five lens elements with refractive powers and surface profiles, including convex and concave portions, made of plastic, satisfying conditions like T5>T4 and BFL/G34≧3.44 to achieve a compact size with improved assembly yield and optical quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the overall length of the imaging lens is reduced, then the device size is miniaturized, but the optical performance deteriorates
Solution Approach 1:
The imaging lens is divided into five separate lens elements (first lens element, second lens element, third lens element, fourth lens element, and fifth lens element) with different refractive powers and surface profiles. This segmentation allows each lens element to be optimized for specific optical functions while maintaining a compact overall structure, resolving the contradiction between miniaturization and optical performance.
Solution Approach 2:
Different lens elements are assigned different surface profiles (convex portions, concave portions) and refractive powers tailored to their specific positions and functions. The first lens element has a convex object-side surface, the second has a concave image-side surface, the third has both convex and concave portions, the fourth has a concave object-side surface, and the fifth is made of plastic material. This local optimization of quality characteristics enables good optical performance within a reduced overall length.
2Manufacturing precision
If the number of lens elements is increased, then the optical performance is improved, but the device complexity increases
Solution Approach 1:
Five lens elements are combined into a single integrated imaging lens structure with a total of 15 surfaces (object-side and image-side surfaces for each element). This merging of multiple functional elements into one compact unit achieves good optical performance while controlling overall structural complexity and assembly requirements.
3Manufacturing precision
If the lens elements are made with specific surface profiles, then the optical aberration is corrected, but the manufacturing difficulty increases
Solution Approach 1:
The lens elements are designed with specific parameter combinations (refractive powers, surface curvatures, thicknesses, and air gaps) that optimize both optical performance and manufacturability. The fifth lens element is made of plastic material with specific refractive index and Abbe number parameters. The air gap between third and fourth lens elements is specifically controlled (G34), and the back focal length (BFL) is optimized relative to G34 (BFL/G34≧3.44), balancing optical quality with assembly feasibility and yield.
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
This configuration allows for a reduced system length while maintaining good optical performance, enhancing imaging quality and assembly yield, facilitating the development of thinner, cost-effective products for portable electronics.
Implementation Method 1
Each of the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element has a refractive power
Data Source
AI summary
An imaging lens includes first to fifth lens elements arranged from an object side to an image side in the given order. Through designs of surfaces of the lens elements and relevant optical parameters, a short system length of the imaging lens may be achieved while maintaining good optical performance.