Wide-Angle Lens Design for Aberration Control
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Solution Overview
Problem
Wide-angle lenses used in image pickup systems face challenges in reducing the F-value and aberration while maintaining a wide viewing angle and minimizing the number of lenses to reduce cost and weight.
Innovation Solution
A wide-angle lens design comprising three plastic lenses with aspherical surfaces, including a negative meniscus first lens and biconvex second and third lenses, with a diaphragm between the second and third lenses, optimized by specific curvature and refractive index conditions to improve astigmatism, field curvature, and chromatic aberration, and featuring hard coating for scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of lenses is reduced to minimize cost and weight, then manufacturing cost and weight are reduced, but the ability to reduce F-value and aberration deteriorates
Solution Approach 1:
The patent applies parameter changes by utilizing plastic lens material with specific refractive indices (n1=1.517-1.545, n2=1.600-1.660, n3=1.500-1.530) and Abbe numbers (ν1=60.0-68.0, ν2=20.0-30.0, ν3=60.0-68.0) to achieve superior aberration correction in a three-lens system. The aspherical surface parameters are optimized with specific coefficients (A4, A6, A8, A10 for each lens surface) to correct spherical aberration, coma, and distortion while maintaining the compact three-lens structure.
Solution Approach 2:
The patent employs composite material principles by combining plastic lens materials with different optical properties (refractive indices and Abbe numbers) to create a multi-material lens system. The first lens uses plastic material with n1=1.517-1.545 and ν1=60.0-68.0, the second lens uses plastic material with n2=1.600-1.660 and ν2=20.0-30.0, and the third lens uses plastic material with n3=1.500-1.530 and ν3=60.0-68.0, creating a composite optical system that achieves superior aberration correction.
2Illumination intensity
If the F-value is reduced to improve brightness, then illumination intensity is improved, but lens complexity and aberration control become more difficult
Solution Approach 1:
The patent achieves F-value reduction to F2.4 while controlling complexity through optimized parameter selection. The focal length f0=1.10-1.30mm, lens spacing d12=0.20-0.40mm, and d23=0.10-0.30mm are carefully selected to achieve the target F-value without excessive complexity. The aspherical surface coefficients are optimized to control aberrations at this low F-value.
Solution Approach 2:
The patent applies spheroidality principles by incorporating aspherical surfaces on all six lens surfaces (object-side and image-side surfaces of all three lenses). The aspherical coefficients (A4, A6, A8, A10) are optimized to control spherical aberration, coma, and distortion that become more pronounced at low F-values, enabling F2.4 performance without excessive complexity.
3Manufacturing precision
If aspherical surfaces are used to improve resolution and reduce aberration, then manufacturing precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes aspherical surface parameters with specific coefficient ranges (A4, A6, A8, A10 for each surface) to achieve superior resolution while managing manufacturing complexity. The parameters are selected to balance optical performance with manufacturability of plastic aspherical lenses.
Solution Approach 2:
The patent applies local quality principles by providing different aspherical characteristics at different zones of each lens surface through the aspherical coefficients. Each lens surface has tailored aspherical parameters optimized for its specific location and function within the optical system, enabling precise local aberration correction.
4Area of stationary object
If a wide viewing angle of 90 degrees or more is achieved, then field of view is improved, but aberration control and resolution deteriorate
Solution Approach 1:
The patent applies spheroidality principles extensively by using aspherical surfaces on all six lens surfaces to control off-axis aberrations. The aspherical coefficients are optimized to correct field curvature, astigmatism, and distortion that increase with wide viewing angles, enabling 90-degree or greater field of view while maintaining resolution.
Solution Approach 2:
The patent optimizes lens curvature radii (R1 through R6) and spacing parameters (d12, d23) to achieve wide viewing angles while controlling aberrations. The specific parameter ranges are selected to balance field of view expansion with aberration control for wide-angle 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 reduced F-value, improved resolution, and minimized aberration, while maintaining a wide viewing angle and low cost and weight, with enhanced scratch resistance and reduced chromatic aberration.
Implementation Method 1
a first lens 10 which is a plastic lens whose both faces are aspherical and having a negative meniscus shape
Implementation Method 2
an aspherical lens is used as the first lens, the second lens and the third lens. Therefore, the astigmatism and field curvature can be improved
Implementation Method 3
a diaphragm is disposed between the second lens and the third lens which are respectively biconvex lenses having positive power and thus deviation of a focusing position caused by temperature change can be reduced
Implementation Method 4
hard coating is applied on a first face located on the object side of the first lens. According to this structure, even when the first lens is a plastic lens, scratch resistance and abrasion resistance of the first face can be improved
Data Source
AI summary
A wide-angle lens may include a first lens which is a plastic lens having first and second faces that are aspherical and having a negative meniscus shape with a convex surface facing an object side, a second lens which is a plastic lens in a biconvex shape having at least one aspherical face, a third lens which is a plastic lens in a biconvex shape having at least one aspherical face, and a diaphragm provided between the second lens and the third lens. The first lens may be provided closest to the object side and the second lens may be between the first lens and the third lens. A radius of curvature at a center of a second face located on an image side of the first lens “R12” (mm) and a focal length of the wide-angle lens “f0”(mm), satisfy the following condition:R12/f0≦0.9.