Three-Lens Optical System Aperture Stop Placement Aberration Control
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Solution Overview
Problem
Conventional camera mobile phone optical systems face challenges in reducing stray light sensitivity and achieving high image quality due to the arrangement of the front aperture stop, which increases aberrations and chromatic aberration, especially in miniaturized systems with reduced pixel size.
Innovation Solution
A three-lens optical system with specific refractive power configurations, including a first lens with positive refractive power, a second lens with negative refractive power, and a third lens with positive refractive power, where the aperture stop is located between the first and second lenses to control brightness and correct aberrations, using plastic materials for miniaturization and aspheric surfaces to reduce aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aperture stop is arranged at the front aperture (conventional triplet configuration), then the aberration correction is achieved, but the stray light sensitivity increases and image quality deteriorates
Solution Approach 1:
The patent extracts the aperture stop from the conventional front aperture position and relocates it to an intermediate position between the first and second lens elements. This extraction from the traditional position allows the system to maintain aberration correction capabilities while significantly reducing stray light sensitivity and improving image quality.
Solution Approach 2:
The patent introduces an intermediate aperture stop position as a mediator between the front lens elements and the image plane. This intermediate positioning serves as a compromise that balances aberration correction requirements with stray light reduction, allowing light to be controlled more effectively without sacrificing optical performance.
2Volume of moving object
If the optical system is miniaturized with reduced pixel size, then the camera mobile phone becomes thinner and more compact, but the image quality requirement increases and aberration correction becomes more difficult
Solution Approach 1:
The patent employs aspheric surfaces on the first, second, and third lens elements to correct aberrations in the miniaturized optical system. The aspheric configurations allow for better control of light rays in a compact form factor, maintaining high image quality despite the reduced system size and pixel dimensions.
Solution Approach 2:
The patent optimizes various optical parameters including refractive indices (n1=1.5436, n2=1.606, n3=1.53), Abbe numbers (v1=60.3, v2=26.6, v3=55.8), and surface curvatures to achieve aberration correction in a miniaturized system. These parameter adjustments enable high image quality in a compact optical system suitable for thin camera mobile phones.
3Area of stationary object
If the focal length is reduced for wide-angle application, then the field of view increases, but the chromatic aberration and distortion increase
Solution Approach 1:
The patent divides the optical system into three distinct lens elements with specific functions: the first lens element (positive power) provides wide-angle capability, the second lens element (negative power) corrects chromatic aberration, and the third lens element (positive power) corrects distortion. This segmentation of functions allows the system to achieve wide field of view while correcting chromatic aberration and distortion through the coordinated action of individual elements.
Solution Approach 2:
The patent uses composite lens design with different materials having distinct refractive indices and Abbe numbers. The combination of materials (plastic or glass with n1=1.5436, v1=60.3; n2=1.606, v2=26.6; n3=1.53, v3=55.8) creates a composite optical system that corrects chromatic aberration while maintaining wide-angle performance through the synergistic effect of different material properties.
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 effectively improves image quality by reducing stray light sensitivity, correcting chromatic aberration, and miniaturizing the optical system while maintaining high resolution, making it suitable for wide-angle applications with a balanced telecentric and wide field of view.
Implementation Method 1
a first lens element with positive refractive power having a convex front surface and a concave rear surface, the front surface of the first lens being aspheric; a plastic second lens element with negative refractive power having a concave front surface and a convex rear surface, the front surface and the rear surface of the second lens being aspheric; and a plastic third lens element with positive refractive power having a convex front surface and a concave rear surface, the front surface and the rear surface of the third lens being aspheric
Data Source
AI summary
An optical system for taking image comprises three lens elements with refractive power, from the object side to the image side: a first positive lens element having a convex front surface and a concave rear surface, and the front surface being aspheric; a negative plastic second lens element having a concave front surface and a convex rear surface, and the front and rear surfaces thereof being aspheric; a positive plastic third lens element having a convex front surface and a concave rear surface, the front and rear surfaces thereof being aspheric; and an aperture stop located between the first and second lens elements for controlling brightness of the optical system. The focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the optical system is f, and they satisfy the relations: f/f1>0.95, |f/f2|>0.34.