Four-Lens Optical System with Aspheric Elements for Miniaturized Cameras
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Solution Overview
Problem
Conventional optical lens systems for miniaturized digital cameras, particularly in mobile phones, face challenges in achieving higher resolution and image quality due to the increasing pixel size of electronic imaging sensors, and existing solutions with multiple spherical lens elements are cumbersome and difficult to manufacture.
Innovation Solution
A four-lens optical system with a first lens element having positive refractive power, a second lens element with negative refractive power and a concave object-side surface, a third lens element with aspheric surfaces for aberration correction, and a fourth lens element also with aspheric surfaces, along with an aperture stop placement that reduces the system's volume and enhances telecentricity, using plastic materials for injection molding to achieve high precision and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional three-lens systems are used, then the structure is simple, but the image quality cannot satisfy higher resolution requirements
Solution Approach 1:
The optical system is divided into four distinct lens elements with specific refractive power distributions. The first lens element provides strong positive refractive power, the second provides negative refractive power for chromatic aberration correction, and the third and fourth elements serve as correction lenses. This segmentation allows each element to be optimized for specific functions, achieving high image quality while maintaining reasonable structural complexity.
Solution Approach 2:
The patent employs a composite lens structure combining spherical and aspheric surfaces across different lens elements. The third and fourth lens elements incorporate aspheric surfaces to correct various aberrations, while the first two elements use spherical surfaces for chromatic aberration correction. This composite approach integrates different optical principles to achieve superior image quality.
2Manufacturing precision
If multiple spherical lens elements are used, then chromatic aberration can be corrected, but the manufacturing difficulty increases due to bonding processes
Solution Approach 1:
The patent changes the surface geometry parameter from purely spherical to include aspheric surfaces on the third and fourth lens elements. This parameter change enables effective correction of spherical aberration, coma, and astigmatism without requiring complex bonding of multiple spherical elements. The aspheric surfaces provide additional degrees of freedom for aberration correction while simplifying the manufacturing process through injection molding technology.
3Length of moving object
If the aperture stop is located before the second lens element, then the total track length is reduced, but the exit pupil position changes
Solution Approach 1:
The patent optimizes the aperture stop position in the object space dimension, placing it before the second lens element closer to the object side. This positional adjustment in one dimension (object space) achieves compact total track length while the optical design compensates for the exit pupil position change through the refractive power distribution of the four lens elements, maintaining acceptable performance in the image space dimension.
4Volume of moving object
If pixel size of sensors is reduced, then the camera can be miniaturized, but higher image quality is required
Solution Approach 1:
The optical system is divided into four distinct lens elements with specific refractive power distributions. The first lens element provides strong positive refractive power, the second provides negative refractive power for chromatic aberration correction, and the third and fourth elements serve as correction lenses. This segmentation allows each element to be optimized for specific functions, achieving high image quality while maintaining reasonable structural complexity.
Solution Approach 2:
The patent employs a composite lens structure combining spherical and aspheric surfaces across different lens elements. The third and fourth lens elements incorporate aspheric surfaces to correct various aberrations, while the first two elements use spherical surfaces for chromatic aberration correction. This composite approach integrates different optical principles to achieve superior image quality.
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 optical system effectively improves image quality by correcting various aberrations, reducing the system's volume, and enhancing the sensitivity of solid-state sensors, while being more manufacturable and cost-effective compared to traditional glass lens systems.
Implementation Method 1
a first lens element with positive refractive power
Implementation Method 2
a second lens element with negative refractive power mainly serves to correct the chromatic aberration
Implementation Method 3
a third lens element and the fourth lens element serve as correction lenses to balance and correct various aberrations
Data Source
AI summary
An optical lens system for taking image comprises: a first lens element with positive refractive power, an Abbe Number of the first lens element being V1, and it satisfying the relation: 50<V1<60; a second lens element with negative refractive power having a concave object-side surface and a convex image-side surface; a third lens element having a convex object-side surface and a concave image-side surface, at least one of the object-side and the image-side surfaces of the third lens element being aspheric; a fourth lens element having at least one aspheric surface; and an aperture stop being located in front of the second lens element.