Five-Element Optical Imaging Lens for Compact Focal Length
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Solution Overview
Problem
Existing optical imaging lenses for mobile devices face challenges in achieving a longer focal length without increasing lens volume, while maintaining good optical characteristics and imaging quality, especially when the focal length exceeds 8 mm and the F-number is less than 2.6.
Innovation Solution
The design of an optical imaging lens with five lens elements, featuring varying refracting power and specific surface shapes such as convex and concave portions, along with an aperture stop placement, to optimize focal length between 8 mm and 13.5 mm and maintain effective radii less than 2.5 mm, thereby enhancing light entry and reducing aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the focal length is increased to achieve larger field of view and higher optical zoom, then the amplification factor increases, but the lens volume (effective radius) must be increased to maintain light entry
Solution Approach 1:
The optical imaging lens is divided into five lens elements with different refracting powers and surface configurations. Each lens element contributes differently to the overall focal length and light gathering, allowing the system to achieve long focal length (8-13.5mm) while maintaining compact effective radius (≤2.5mm) through distributed optical power rather than a single large element
Solution Approach 2:
Different lens elements have locally optimized surface configurations (convex portions, concave portions, aspherical surfaces) at different regions (periphery vs. center). For example, the second lens element has a convex portion at its periphery, the third lens element has a convex portion at its periphery, and the fourth lens element has a concave portion at its periphery. This local optimization allows each element to contribute efficiently to the overall optical performance within constrained dimensions
2Illumination intensity
If the aperture size is increased to allow more light entry, then the amount of light increases, but the lens volume must be increased
Solution Approach 1:
The aperture function is distributed across five lens elements rather than requiring a single large aperture. Each lens element has its own effective radius (≤2.5mm) that contributes to the overall light gathering capability, allowing the system to achieve Fno < 2.6 (high light entry) while maintaining compact individual element sizes
Solution Approach 2:
The lens elements have locally optimized surface configurations that maximize light transmission within the constrained effective radius. The aspherical surfaces of the fifth lens element and the specific convex/concave configurations of other elements are designed to minimize aberrations and maximize light gathering efficiency within the small effective radius, achieving high illumination intensity without increasing overall lens volume
3Manufacturing precision
If the lens elements are designed with complex surface shapes to improve imaging quality, then optical characteristics improve, but manufacturing difficulty increases
Solution Approach 1:
The complex surface configurations are applied locally to specific lens elements rather than uniformly across all elements. Only the fifth lens element has aspherical surfaces on both object-side and image-side, while other elements have simpler configurations (convex or concave portions at periphery). This selective application of complexity achieves high imaging quality while minimizing overall manufacturing difficulty
Solution Approach 2:
The optical system is segmented into five elements with progressively increasing complexity. The first four elements have relatively simpler surface configurations (spherical with localized convex/concave portions), while the fifth element handles the aspherical complexity. This segmentation allows manufacturers to produce simpler elements at higher volumes and lower cost, while the single aspherical element can be manufactured with specialized techniques
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 shortened lens length while maintaining high imaging quality and light entry, effectively addressing the challenge of increasing focal length without enlarging the lens volume, and improving manufacturing ease and yield.
Implementation Method 1
Each of the first to fifth lens elements may have varying refracting power... f1 The focusing length of the first lens element, f2 The focusing length of the second lens element, f3 The focusing length of the third lens element, f4 The focusing length of the fourth lens element, f5 The focusing length of the fifth lens element, n1 The refracting index of the first lens element, n2 The refracting index of the second lens element, n3 The refracting index of the third lens element, n4 The refracting index of the fourth lens element, n5 The refracting index of the fifth lens element
Data Source
AI summary
Present embodiments relate to an optical imaging lens. The optical imaging lens may include a first lens element, a second lens element, a third lens element, a fourth lens element, and a fifth lens element positioned sequentially from an object side to an image side. Through arrangement of convex or concave surfaces of the five lens elements, the length of the optical imaging lens may be shortened while providing improved optical characteristics and imaging quality.