Two-Element Aspheric Lens Assembly for Compact Optical Design
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Solution Overview
Problem
Conventional photographing optical lens assemblies face challenges in achieving a compact form while maintaining image quality due to the difficulty in incorporating multiple lens elements and manufacturing issues related to lens thickness and refractive power distribution.
Innovation Solution
A photographing optical lens assembly comprising a first lens element with positive refractive power and a second lens element with positive refractive power, both having aspheric surfaces, is designed to optimize the total optical length and reduce sensitivity, with specific conditions for axial distances and Abbe numbers to balance image quality and manufacturing feasibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If three lens elements are used for aberration correction, then image quality is improved, but the lens assembly length increases and manufacturing difficulty increases
Solution Approach 1:
The patent removes the middle lens element from the conventional three-element structure, extracting only the necessary refractive functions while eliminating the component that causes excessive length. This results in a two-element design that achieves aberration correction without requiring the full three-element configuration.
Solution Approach 2:
The patent changes the refractive power parameters of the remaining lens elements. The first lens element has positive refractive power with specific curvature radii, and the second lens element has negative refractive power, creating a balanced optical system that achieves the desired image quality with reduced length.
2Length of moving object
If lens elements are made thinner to reduce length, then lens assembly length is reduced, but manufacturing uniformity deteriorates
Solution Approach 1:
The patent applies different thickness characteristics to different lens elements according to their specific optical functions. The first lens element has a specific thickness range that ensures manufacturing feasibility while providing the required refractive power, and the second lens element is designed accordingly, allowing each element to have optimal local properties.
3Ease of manufacture
If conventional lens elements are used, then manufacturing process is simple, but total optical length cannot be shortened
Solution Approach 1:
The patent employs aspheric surfaces on the lens elements instead of conventional spherical surfaces. The aspheric coefficients are specifically designed to optimize the optical path and reduce the total length while maintaining manufacturability. This curvature optimization allows the lens assembly to achieve compact length without sacrificing the ability to be manufactured by conventional processes.
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 solution effectively shortens the total optical length, corrects aberrations, and improves image sensor performance, making it suitable for compact devices while reducing manufacturing costs and weight.
Implementation Method 1
a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface, and a second lens element with positive refractive power having a concave object-side surface and a convex image-side surface
Implementation Method 2
At least one of the object-side and the image-side surfaces of the first lens element are aspheric and the object-side and the image-side surfaces of the second lens element are aspheric
Data Source
AI summary
A photographing optical lens assembly includes, in order from an object side to an image side, a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface, and a second lens element with positive refractive power having a concave object-side surface and a convex image-side surface. At least one surface of the first lens element is aspheric and two surfaces of the second lens element are aspheric. The photographing optical lens assembly can also include a stop and an image plane. By adjusting the thicknesses of the first lens element and the second lens element as well as the allocation of the stop in the photographing optical lens assembly can effectively reduce the size as well as the sensitivity of the photographing optical lens assembly while gaining superior resolution.