Five-Lens Optical System Astigmatism Correction
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Solution Overview
Problem
Conventional optical systems in portable electronic devices, such as smartphones and PDAs, face challenges in achieving high image quality due to inadequate astigmatism correction and excessive total track length, particularly with five-lens element systems that are not optimally arranged.
Innovation Solution
An optical image capturing system with five lens elements, including a first lens with positive refractive power, a second with negative refractive power, a third with negative refractive power, a fourth with a concave image-side surface, and a fifth with a concave image-side surface and at least one inflection point, optimized to satisfy specific relationships between curvature radii and Abbe numbers for improved image quality and astigmatism correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical system with five lens elements is used, then the system can achieve higher megapixels, but the total track length becomes too long and astigmatism correction is poor
Solution Approach 1:
The patent applies parameter changes by optimizing the curvature radii relationships (specifically f/|R5| + f/|R6| < 1.0) and Abbe number relationships (0.20 < V4/V1 < 0.60) of the lens elements. These parameter optimizations enable the five-lens system to achieve compact dimensions while maintaining high image quality and effective astigmatism correction, resolving the contradiction between image quality and total track length.
2Measurement precision
If the third and fourth lens elements are arranged in conventional configurations, then the system structure is simple, but astigmatism correction is not effective
Solution Approach 1:
The patent applies local quality by assigning specific optical properties to specific lens elements: the third lens element has negative refractive power with optimized curvature radii, while the fourth lens element has positive refractive power with an inflection point on its image-side surface. This localized optimization of lens characteristics enables effective astigmatism correction without requiring complex overall system restructuring.
3Manufacturing precision
If aspheric surfaces are used on the fourth and fifth lens elements, then manufacturing precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by defining specific aspheric surface equations with controlled coefficients for the fourth and fifth lens elements. The aspheric surfaces are designed with inflection points and specific curvature relationships that, while precise, follow standardized mathematical forms that can be manufactured using modern molding or grinding techniques, balancing manufacturing precision with feasibility.
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 achieves better image quality and astigmatism correction, reducing the total track length and enhancing manufacturing yield, while allowing for flexible design with either plastic or glass materials, and includes a stop for improved exposure and image resolution.
Implementation Method 1
five lens elements with refractive power, in order from an object side to an image side, 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 image capturing system includes five lens elements with refractive power, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element with negative refractive power has a concave image-side surface. The third lens element has negative refractive power. The fourth lens element with refractive power has a concave image-side surface, and the surfaces of the fourth lens element are aspheric. The fifth lens element with refractive power has a concave image-side surface, wherein at least one inflection point formed on the image-side surface thereof, and the surfaces of the fifth lens element are aspheric.