Three-Lens Imaging System with Aspheric Third Lens for Aberration Correction
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Solution Overview
Problem
Conventional imaging lenses for small cameras face challenges in achieving both downsizing and a wide angle while effectively correcting aberrations and distortion, with existing solutions either requiring high precision in fabrication and assembly or limiting performance improvements.
Innovation Solution
A three-lens configuration with positive refractive power for each lens, where the first lens has a stronger refractive power than the second and third lenses, and the third lens is aspheric with inflection points, satisfying specific conditional expressions to optimize focal length, curvature radii, and Abbe's number for improved performance and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a three-lens configuration with negative refractive power for the second lens is used, then chromatic aberration is corrected and downsizing is achieved, but manufacturing precision requirements increase and assembly complexity increases
Solution Approach 1:
The patent changes the refractive power parameter of the second lens from negative to positive, which fundamentally alters the optical path and aberration correction mechanism. This parameter change allows the lens to achieve aberration correction through different optical principles (spherical aberration correction via positive power) rather than relying on negative power chromatic aberration correction, thereby reducing manufacturing and assembly precision requirements
Solution Approach 2:
The patent employs composite lens design where the second lens with positive refractive power works in combination with the first and third lenses to achieve overall aberration correction. The specific refractive indices and Abbe numbers of different lens materials are optimized to work together, allowing positive power lenses to collectively correct both spherical and chromatic aberrations that were previously handled by the negative power lens
2Manufacturing precision
If the focal length is increased to correct aberrations and distortion, then image quality improves, but the optical axis length increases and device size increases
Solution Approach 1:
The patent divides the optical system into three distinct lens units, each with specific positive refractive powers. The first lens handles initial light convergence, the second lens corrects spherical aberration, and the third lens provides final focusing. This segmentation allows each lens to contribute to aberration correction without requiring any single lens to have excessive focal length, thereby maintaining compact optical axis length
Solution Approach 2:
The patent utilizes aspheric surfaces with inflection points on the third lens to correct distortion and higher-order aberrations. The curved surfaces are specifically designed with mathematical precision to provide the necessary optical power distribution, allowing effective aberration correction in a shorter focal length configuration rather than requiring long focal length spherical lenses
3Adaptability or versatility
If the angle of view is widened for diverse camera applications, then versatility improves, but aberration correction becomes more difficult and optical axis length increases
Solution Approach 1:
The patent optimizes the refractive power distribution among the three lenses with specific relationships (f2 < f3 and f1/f2 within 0.3-1.7) to handle wide-angle light rays. The second lens with positive power is specifically designed to correct coma and astigmatism that are prominent in wide-angle applications, maintaining aberration correction precision across the expanded field of view
Solution Approach 2:
The aspheric surfaces with inflection points on the third lens are specifically designed to correct field curvature and distortion that increase with wider angles of view. The mathematical formulation of these aspheric surfaces compensates for the increased aberrations inherent in wide-angle optics, maintaining image quality across the expanded viewing angle without increasing optical axis length
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 the attainment of both downsizing and a wide angle while effectively correcting aberrations and distortion, reducing manufacturing costs and improving image-forming performance across various camera applications.
Implementation Method 1
a first lens having positive refractive power; a second lens having positive refractive power; and a third lens having positive refractive power, arranged in the order from an object side to an image plane side
Implementation Method 2
The third lens has an object-side surface and an image plane-side surface that have positive curvature radii. In addition, the object-side surface and the image plane-side surface of the third lens are respectively formed as aspheric surfaces having inflexion points
Data Source
AI summary
An imaging lens includes a first lens; a second lens; and a third lens arranged from an object side to an image plane side. The first lens has an object-side surface having a positive curvature radius R1f and an image plane-side surface having a negative curvature radius R1r. The second lens has an object-side surface and an image plane-side surface with negative curvature radii. The third lens has an object-side surface and an image plane-side surface with positive curvature radii and formed as aspheric surfaces having inflexion points. When the whole lens system has a focal length f, the first lens has a focal length f1, the second lens has a focal length f2, and the third lens has a focal length f3, the imaging lens satisfies the following conditional expressions:f1<f2<f31.0<f1/f<1.5−0.02<R1f/R1r<0