Three-Element Optical Imaging Lens With Aspheric Surfaces
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Solution Overview
Problem
Current miniaturized optical imaging lenses for mobile devices face challenges in achieving a wider angle of view, high resolution, and low manufacturing cost while maintaining image quality, with existing lenses having small angles of view and aperture values.
Innovation Solution
An optical imaging lens design comprising three lens elements with specific refractive powers and aspheric surfaces, including a plastic second and third lens element with inflection points, and an aperture stop placement to reduce spherical aberration, astigmatism, and chromatic aberration, while optimizing the radius of curvature and thickness ratios to enhance image quality and field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If more than five or six lens elements are used to provide wider angle of view and higher resolution, then image quality and field of view are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the parameters of existing lens elements by introducing aspheric surfaces with specific conic constants (k values) and optimizing curvature radii, thicknesses, and spacing. This allows a three-element lens to achieve performance comparable to or better than five or six element spherical lenses, resolving the contradiction between image quality and device complexity
Solution Approach 2:
The patent employs aspheric surfaces instead of spherical surfaces for all lens elements. The aspheric conic constants are specifically designed (e.g., k1=-2.0, k2=-2.0, k3=-1.3868E+01) to correct aberrations and achieve wide angle of view (87.10 degrees) and high resolution with only three lens elements, thereby reducing device complexity while maintaining image quality
2Ease of manufacture
If three lens elements are used to reduce device complexity and manufacturing cost, then manufacturing cost and ease of manufacture are improved, but angle of view and aperture value are reduced
Solution Approach 1:
The patent optimizes the parameters of three lens elements including curvature radii (R1-R6), thicknesses (CT2, CT3, T12), and spacing to achieve an angle of view of 87.10 degrees and aperture value of f/2.4. This resolves the contradiction by showing that three elements can provide wide angle of view when properly designed with aspheric surfaces
Solution Approach 2:
By using aspheric surfaces with specific conic constants for all three lens elements, the patent achieves wide angle of view (87.10 degrees) and high aperture value (f/2.4) while maintaining only three lens elements. The aspheric design allows the lens to correct aberrations and provide versatile imaging performance with minimal elements
3Measurement precision
If aspheric surfaces with specific conic constants are used to reduce spherical aberration and astigmatism, then image quality is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise conic constant values (k1=-2.0, k2=-2.0, k3=-1.3868E+01) and curvature radii for the aspheric surfaces. By providing these specific parameters, the patent enables manufacturers to reproduce the optimal aberration correction while managing manufacturing precision requirements through clear design specifications
Solution Approach 2:
The patent uses aspheric surfaces with specific conic constants to correct spherical aberration and astigmatism. The conic constants are optimized to balance aberration correction with manufacturability, allowing precise control over surface shape while maintaining practical manufacturing capabilities
4Ease of manufacture
If plastic materials are used for lens elements to reduce manufacturing cost, then manufacturing cost is reduced, but refractive index control and aberration correction become more difficult
Solution Approach 1:
The patent specifies precise refractive indices (N2=1.535, N3=1.642) and Abbe numbers (V2=57.0, V3=22.0) for the plastic lens materials. By providing these specific parameters, the patent enables accurate refractive index control and aberration correction while using cost-effective plastic materials instead of glass
Solution Approach 2:
The patent uses plastic materials with specifically selected optical properties (refractive indices and Abbe numbers) for the lens elements. The combination of plastic materials with optimized parameters achieves both cost reduction and maintained image quality, resolving the contradiction between manufacturing cost and optical performance
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 design achieves a wider angle of view, improved image quality, and reduced manufacturing sensitivity, effectively addressing the limitations of existing lenses by minimizing aberrations and maintaining a low manufacturing cost.
Implementation Method 1
a first lens element with a positive refractive power having an aspheric object-side surface being convex near the optical axis and an aspheric image-side surface; a second lens element with a positive refractive power having an aspheric object-side surface being concave near the optical axis and an aspheric image-side surface being convex near the optical axis
Data Source
AI summary
An optical imaging lens includes an aperture stop and an optical assembly, the optical assembly includes, in order from the object side to the image side: a first lens element with a positive refractive power; a second lens element with a positive refractive power; a third lens element with a negative refractive power; the aperture stop is located between an image-side surface of the first lens element and an object to be photographed; wherein a radius of curvature of an object-side surface of the first lens element is R1, a radius of curvature of the image-side surface of the first lens element is R2, a central thickness of the second lens element is CT2, a central thickness of the third lens element is CT3, and the following conditions are satisfied:−2.0<(R1+R2)/(R1−R2)<−0.2; 2.0<CT2/CT3<4.0.