Five-Lens Plastic Optical Design for Compact Camera Aberration Correction
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Solution Overview
Problem
Conventional optical lenses for compact electronic devices, such as digital still cameras and mobile phone cameras, face challenges in achieving a compact design with good aberration correction, high resolution, and low manufacturing costs, particularly in maintaining image quality and reducing the total length of the optical system.
Innovation Solution
A five-lens optical lens design is proposed, comprising a first lens element with positive refractive power, a second lens element with negative refractive power, a third lens element with refractive power, a fourth lens element made of plastic with positive refractive power and aspheric surfaces, and a fifth lens element made of plastic with negative refractive power and an inflection point, optimized by specific curvature radius and thickness ratios to achieve aberration correction and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a five-lens optical lens design with plastic materials is used, then manufacturing cost is reduced, but aberration correction ability may deteriorate
Solution Approach 1:
The patent employs a composite lens structure combining plastic materials with specific refractive indices and Abbe numbers. The fourth lens element uses plastic with refractive index 1.65-1.75 and Abbe number 20-40, while the fifth lens element uses plastic with refractive index 1.60-1.70 and Abbe number 25-50. This material selection achieves both cost reduction and aberration correction by carefully balancing the optical properties of plastic materials.
Solution Approach 2:
The patent optimizes multiple parameters including curvature radii (R3, R4, R7, R8), thicknesses (CT3, CT4, CT5), and refractive indices to achieve aberration correction. Specific parameter relationships are established: -1.07 < (R3+R4)/(R3-R4) × CT4/CT5 < 0.22 and -1.07 < R7/R8 < 0.22, which balance optical performance with manufacturing feasibility.
2Length of moving object
If the optical system is made compact, then device size is reduced, but aberration correction becomes more difficult
Solution Approach 1:
The optical system is divided into five lens elements with alternating positive and negative refractive powers. The first lens element (positive) and second lens element (negative) form one group, while the third lens element (positive) and fourth lens element (positive) form another group, with the fifth lens element (negative) providing additional correction. This segmentation allows compact arrangement while maintaining aberration correction capability through distributed optical power.
Solution Approach 2:
The patent employs aspheric surfaces with specific conic coefficients (K1, K2, K3, K4, K5) for the lens elements. The aspheric coefficients are optimized to balance aberration correction with compact design, allowing the optical system to achieve high image quality within a reduced total length.
3Manufacturing precision
If cemented glass lenses are used, then optical performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive cemented glass lenses with affordable plastic lens elements. The fifth lens element is specifically designed as a plastic meniscus lens with inflection points, providing the necessary optical correction at a lower cost. This substitution maintains adequate optical performance while significantly reducing manufacturing costs for mass production.
Solution Approach 2:
The patent selects plastic materials with specific refractive indices (1.65-1.75 for the fourth element, 1.60-1.70 for the fifth element) and Abbe numbers (20-40 and 25-50 respectively) to achieve optical performance comparable to glass lenses at a lower cost. The parameter optimization ensures that the plastic lenses can fulfill the required optical functions.
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 design effectively corrects aberrations, reduces the total length of the optical system, and lowers production costs by using plastic lens elements, while maintaining high image quality and sensitivity, enabling a greater effective pixel range with a compact lens assembly.
Implementation Method 1
an optical lens for image pickup, sequentially arranged from an object side to an image side along an optical axis, comprising: a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element
Data Source
AI summary
An optical lens for image pickup, sequentially arranged from an object side to an image side along the optical axis comprising: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with refractive power; a plastic fourth lens element with positive refractive power having biconvex surfaces with at least one aspheric surface; and a plastic fifth lens element with negative refractive power having a concave image-side surface, with at least one aspheric surface and at least one inflection point. By such arrangements, the optical lens for image pickup satisfies conditions related to shorten the total length and to reduce the sensitivity for use in compact cameras and mobile phones with camera functionalities.