Wide-Angle Imaging Lens With Aspherical Cemented Interface
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Solution Overview
Problem
Current wide-angle imaging lenses for vehicle and surveillance cameras face challenges in achieving a balance between reduced size, increased angle, and high performance while maintaining brightness and cost-effectiveness, with existing designs often resulting in high-order aberrations and limited optical performance.
Innovation Solution
A wide-angle imaging lens configuration comprising a negative meniscus first lens, a negative second lens, a positive third lens, an aperture stop, a negative fourth lens, and a positive fifth lens, where the fourth and fifth lenses are cemented with an aspherical interface convex on the object side, satisfying specific conditional expressions to optimize refractive power distribution and correct aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of lenses is reduced to achieve downsizing and cost reduction, then manufacturing cost and device size are reduced, but optical performance deteriorates due to high-order aberrations
Solution Approach 1:
The patent applies an aspherical surface to the image-side surface of the fourth lens. This aspherical design allows the lens to correct high-order aberrations (spherical aberration, coma, astigmatism) more effectively than traditional spherical surfaces, thereby maintaining high optical performance while using fewer lens elements. The aspherical coefficient is specifically optimized to balance aberration correction with manufacturing feasibility.
2Area of stationary object
If the angle of view is increased to achieve wider imaging coverage, then the field of view is expanded, but aberrations increase and optical performance deteriorates
Solution Approach 1:
The patent implements local quality optimization by assigning specific surface shapes and refractive powers to different lens elements. The fourth lens has a meniscus shape with an aspherical image-side surface, while the fifth lens has a biconvex shape. This localized optimization of each lens element's properties enables effective aberration correction across the wide angle of view without requiring a complex multi-element design.
Solution Approach 2:
The patent utilizes parameter optimization by carefully selecting the refractive indices and Abbe numbers of the lens materials. The fourth lens uses material with refractive index between 1.60-1.80 and Abbe number between 30-50, while the fifth lens uses material with refractive index between 1.50-1.70 and Abbe number between 30-60. These parameter ranges are optimized to control chromatic aberration and other optical aberrations across the wide field of view.
3Illumination intensity
If the F-number is reduced to achieve brighter imaging, then light gathering ability is improved, but aberrations increase and resolving power decreases
Solution Approach 1:
The aspherical surface on the fourth lens is particularly effective at controlling spherical aberration and coma that become prominent at low F-numbers. This allows the lens to maintain an F-number of 2.0 or lower (brighter imaging) while preserving high resolving power across the entire image field. The aspherical profile optimizes light ray convergence to minimize aberrations even with large aperture.
4Device complexity
If the lens structure is simplified to achieve cost reduction, then manufacturing complexity is reduced, but the ability to correct aberrations is compromised
Solution Approach 1:
The patent combines multiple functions into fewer lens elements. The fourth lens integrates negative refractive power with an aspherical surface to simultaneously correct spherical aberration, coma, and astigmatism. The cemented lens structure of the fourth and fifth lenses merges chromatic aberration correction with monochromatic aberration correction, achieving comprehensive aberration control with only five lens elements total.
Solution Approach 2:
The patent uses composite material properties by selecting specific refractive index and Abbe number combinations for the fourth and fifth lenses. The fourth lens material (refractive index 1.60-1.80, Abbe number 30-50) and fifth lens material (refractive index 1.50-1.70, Abbe number 30-60) are chosen to create favorable chromatic aberration correction through the cemented interface, while the aspherical surface provides additional degrees of freedom for correcting monochromatic aberrations.
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 solution enables a compact, cost-effective wide-angle imaging lens with high resolving power and reduced aberrations, achieving improved optical performance and image quality across the imaging area without generating high-order aberrations.
Implementation Method 1
a negative fourth lens and a positive fifth lens disposed in order from the object side, wherein the fourth lens and the fifth lens are cemented with an interface which is convex on the object side and has an aspherical shape
Data Source
AI summary
An imaging lens is composed of a first lens having a negative meniscus shape with a convex surface on the object side, a negative second lens, a positive third lens, an aperture stop, a negative fourth lens, and a positive fifth lens disposed in order from the object side. The fourth and the fifth lens are cemented with an interface which is convex on the object side and has an aspherical shape. If the radius of curvature is taken as R9 and the focal length of the entire system is taken as f, the imaging lens satisfies a conditional expression given below:1.0<R9/f  (1).