Imaging Lens Aberration Correction via Aspheric Surfaces
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Solution Overview
Problem
Conventional imaging lenses for small cameras, such as smartphones, face challenges in achieving both downsizing and satisfactory aberration correction, particularly due to the limitations in chromatic aberration, astigmatism, and field curvature, which hinder high-resolution imaging while maintaining a compact size.
Innovation Solution
The imaging lens configuration includes a first lens group with positive and negative refractive powers, and a second lens group with specific focal length and Abbe's number ratios, along with aspheric surfaces, to optimize refractive power distribution and correct aberrations, ensuring balanced chromatic aberration, astigmatism, and field curvature correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of lenses is increased to achieve high-resolution imaging, then the imaging resolution is improved, but the total track length increases making the lens unsuitable for small cameras
Solution Approach 1:
The patent applies local quality by using aspheric surfaces on specific lens elements (first, third, and sixth lenses) rather than making all lenses aspheric. This selective application corrects local aberration problems (spherical aberration, coma, astigmatism) in critical regions while maintaining a compact overall structure, resolving the contradiction between high resolution and short total track length
Solution Approach 2:
The patent uses composite lens design combining different refractive index materials (lens materials with specific refractive indices and Abbe numbers as defined in the claims) to achieve superior aberration correction in a compact configuration. The combination of positive and negative lenses with specific material properties enables high-resolution imaging without increasing total track length
2Length of stationary object
If the total track length is shortened to downsize the imaging lens, then the compactness is improved, but the aberration correction performance deteriorates
Solution Approach 1:
The patent employs aspheric surfaces on the first, third, and sixth lenses to correct various aberrations (spherical aberration, coma, astigmatism, field curvature) within a shortened total track length. The aspheric profiles enable precise control of light paths, achieving satisfactory aberration correction despite the compact size
Solution Approach 2:
The patent optimizes specific parameter ranges (focal length ratios, Abbe number ratios, refractive index ratios as defined in the claims) to achieve balanced aberration correction in a compact design. By carefully controlling these parameters, the lens achieves both short total track length and high correction performance
3Manufacturing precision
If a six-lens configuration is used to achieve satisfactory aberration correction, then the aberration correction is improved, but the device complexity increases
Solution Approach 1:
The patent divides the imaging lens into two functional groups (first lens group with positive refractive power and second lens group with negative refractive power) to systematically manage aberration correction. This segmentation allows each group to address specific aberration types, achieving comprehensive correction while maintaining design clarity and manufacturing 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
This configuration allows for a small-sized imaging lens with high resolution and effective aberration correction, enabling improved image-forming performance and compactness suitable for small cameras like smartphones and portable devices.
Implementation Method 1
a first lens having positive refractive power, a second lens having positive refractive power, and a third lens having negative refractive power... the first lens has an Abbe's number νd1, the second lens has an Abbe's number νd2, and the third lens has an Abbe's number νd3
Implementation Method 2
satisfy the following conditional expressions (1) to (4)... achievable to restrain a chromatic aberration, an astigmatism, and a field curvature respectively within preferred ranges
Implementation Method 3
The first lens group includes a first lens having positive refractive power, a second lens having positive refractive power, and a third lens having negative refractive power... achievable to restrain a chromatic aberration, an astigmatism, and a field curvature
Implementation Method 4
satisfy the following conditional expressions (1) to (4)... achievable to restrain a chromatic aberration, an astigmatism, and a field curvature respectively within preferred ranges
Implementation Method 5
The second lens group includes a fourth lens having negative refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power... the fourth lens has a focal length f4, the fifth lens has a focal length f5, and the sixth lens has a focal length f6
Implementation Method 6
satisfy the following conditional expressions (1) to (4)... achievable to restrain a chromatic aberration, an astigmatism, and a field curvature respectively within preferred ranges
Data Source
AI summary
An imaging lens includes a first lens group and a second lens group, arranged in this order from an object side to an image plane side. The first lens group includes a first lens, a second lens, and a third lens. The second lens group includes a fourth lens, a fifth lens having negative refractive power, and a sixth lens having positive refractive power. The first lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side have positive curvature radii. The sixth lens is formed in a shape so that a surface thereof on the object side and a surface thereof on the image plane side are aspheric. The sixth lens has a specific Abbe's number.