Five-Lens Plastic Optical System Aberration Correction
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Solution Overview
Problem
Conventional optical lens assemblies for compact electronic devices, such as digital cameras and mobile phones, face challenges in achieving a balance between short total length, good aberration correction, and cost-effectiveness, particularly with five-lens designs where the excess length and complexity of fabrication hinder these goals.
Innovation Solution
The design incorporates a specific arrangement of five lens elements with varying refractive powers and surface shapes, including aspheric surfaces and inflection points, to optimize the optical system's length and image quality, using plastic for the fifth lens element to simplify manufacturing and reduce costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If five lens elements are used to improve aberration correction and image quality, then aberration correction ability and resolution are improved, but total length of the optical system increases
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive powers, curvatures, and axial distances of the five lens elements. Specifically, the fourth lens element has a positive refractive power with a convex object-side surface and concave image-side surface, while the fifth lens element has a negative refractive power. The axial distance between the fourth and fifth lens elements is controlled within a specific range (0.05f to 0.15f) to achieve compact length while maintaining aberration correction
Solution Approach 2:
The patent uses composite material approach by combining different materials for the lens elements. The first three lens elements use high refractive index materials (n1≥1.6, n2≥1.6, n3≥1.5) while the fourth and fifth lens elements use materials with lower refractive indices (n4<1.5, n5<1.5). This material composition strategy enables better aberration correction with reduced optical path length
2Length of stationary object
If complex surface designs (inflection points, aspheric surfaces) are used to correct aberration and shorten length, then image quality and compactness are improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality principle by introducing inflection points only on specific surfaces where needed for aberration correction. The fourth lens element has an inflection point on its object-side surface, and the fifth lens element has an inflection point on its image-side surface. This localized application of complex geometry minimizes manufacturing complexity while achieving the desired optical performance and compact length
3Measurement precision
If fourth and fifth lens elements are designed with inflection points to correct aberration, then aberration correction is improved, but gap between third and fourth lens elements increases
Solution Approach 1:
The patent resolves this contradiction through precise parameter control. The axial distance between the third and fourth lens elements (T34) is controlled within the range of 0.03f to 0.08f, and the axial distance between the fourth and fifth lens elements (T45) is controlled within 0.05f to 0.15f. These parameter constraints enable aberration correction via inflection points while maintaining compact spacing between lens elements
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 effectively shortens the optical lens assembly while maintaining high image quality and aberration correction, enabling a more compact and cost-effective solution for electronic devices.
Implementation Method 1
the first lens element with positive refractive power, the second lens element with positive refractive power, the third lens element with refractive power, the fourth lens element with refractive power, and the fifth lens element with refractive power
Data Source
AI summary
An imagery optical system, sequentially from an object side to an image side on an optical axis comprising: the first lens element with positive refractive power, the second lens element with positive refractive power, the third lens element, the fourth lens element, and the fifth lens element having at least one inflection point. Each of the five lens elements may be made of plastic and comes with bi-aspheric surfaces. The imagery optical system satisfies conditions related to shorten the total length and to reduce the sensitivity for use in compact cameras and mobile phones with a camera function.