Imaging Lens Aberration Correction via Refractive Power Sharing
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Solution Overview
Problem
Conventional imaging lenses for small cameras face challenges in achieving both downsizing and satisfactory aberration correction, particularly in smartphones and other portable devices, due to the limitations of lens configuration and materials used.
Innovation Solution
The proposed imaging lens configuration includes a first lens group with positive refractive power, a second lens group with positive refractive power, and a third lens group with negative refractive power, specifically arranged to share refractive power between the first and second lens groups, using low-dispersion and high-dispersion materials to correct chromatic aberration, while the seventh lens is made of low-dispersion material to restrain chromatic aberration, and the focal length ratios are optimized to balance aberration correction and downsizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of lenses is increased to achieve high-resolution imaging, then the imaging resolution is improved, but the size of the imaging lens increases
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive indices and Abbe numbers of lens materials. Specifically, it uses a first lens with positive refractive power and a second lens with negative refractive power, where the ratio of their focal lengths and the Abbe numbers are controlled within specific ranges. This allows achieving high-resolution imaging with fewer lenses by changing the optical parameters of the materials rather than simply increasing the number of lens elements.
Solution Approach 2:
The patent employs composite material principles by combining lenses made of different materials with specific refractive index characteristics. It uses a first lens made of a material with a specific refractive index range and a second lens made of a material with different refractive index characteristics, creating a composite optical system that achieves both high resolution and compact size through material property optimization rather than numerical increase of components.
2Length of stationary object
If the number of lenses is reduced to downsize the imaging lens, then the imaging lens size is reduced, but the aberration correction capability deteriorates
Solution Approach 1:
The patent addresses aberration correction in a compact design by changing the optical parameters of the lens materials. It specifies that the first lens should have positive refractive power with a focal length and Abbe number within certain ranges, and the second lens should have negative refractive power with controlled focal length ratio. These parameter optimizations enable effective aberration correction using only two lens elements, maintaining reliability while minimizing size.
Solution Approach 2:
The patent applies local quality principles by assigning specific material properties to specific lens positions. The first lens is designed with positive refractive power and specific Abbe number characteristics suitable for its position in the optical path, while the second lens is designed with negative refractive power and different material characteristics. This localized optimization of material properties at different positions enables effective aberration correction with minimal components.
3Length of stationary object
If the refractive power is concentrated in one lens group to downsize the imaging lens, then the imaging lens size is reduced, but the chromatic aberration increases
Solution Approach 1:
The patent applies segmentation by dividing the refractive power into two separate lens elements rather than concentrating it in one lens. The first lens with positive refractive power and the second lens with negative refractive power are segmented as distinct optical components, each contributing to the overall focusing power while independently addressing chromatic aberration through their specific material properties and positions in the optical path.
Solution Approach 2:
The patent uses composite material principles to address chromatic aberration by combining lenses made of materials with different refractive index characteristics. The first lens uses a material with specific refractive index and Abbe number, while the second lens uses a material with different characteristics, creating a composite optical system that disperses chromatic effects across multiple material interfaces rather than concentrating them in a single element.
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, including chromatic, coma, astigmatism, and distortion, while maintaining a compact design suitable for small cameras.
Implementation Method 1
a first lens having positive refractive power, a second lens having negative refractive power
Implementation Method 2
using low-dispersion and high-dispersion materials to correct chromatic aberration
Data Source
AI summary
An imaging lens includes a first lens; a second lens; a third lens having negative refractive power; a fourth lens; a fifth lens; a sixth lens; and a seventh lens, arranged in this order from an object side to an image plane side. The sixth lens is formed in a shape so that a surface thereof on the image plane side is concave at a paraxial region thereof. The seventh lens is formed in a shape so that a surface thereof on the image plane side is aspheric. The first lens and the second lens have a specific composite focal length. The third lens have a specific focal length.