Four-Element Plastic Lens Aberration Control
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Solution Overview
Problem
Conventional compact imaging lens systems for portable electronic devices face challenges in achieving high image quality while maintaining a moderate total track length and being compact, due to excessive spherical glass lenses and complex manufacturing processes, which also lead to issues with unnecessary light reflection and aberrations.
Innovation Solution
A four-lens-element image lens system with specific refractive power distributions and aspheric surfaces made of plastic, including a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power, and a fourth lens with negative refractive power, optimized to balance refractive power and correct aberrations, reducing the total track length and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional three-lens-element systems are used, then the structure is simple and manufacturing is easier, but the image quality and resolving power are insufficient
Solution Approach 1:
The patent divides the imaging system into four distinct lens elements with specific refractive power distributions (positive, negative, positive, negative), allowing each element to contribute differently to aberration correction and image quality enhancement, thereby resolving the contradiction between manufacturing simplicity and image quality
Solution Approach 2:
The patent employs aspheric surfaces on all lens elements and specifies precise curvature radii, thicknesses, and refractive indices, changing the geometric and optical parameters from conventional spherical designs to achieve superior image quality while maintaining manufacturability through standardized aspheric manufacturing processes
2Manufacturing precision
If multiple spherical glass lenses are used to correct aberrations, then image quality improves, but the total track length increases and manufacturing becomes more complicated
Solution Approach 1:
The patent replaces conventional spherical lens surfaces with aspheric surfaces on all four lens elements, enabling more effective aberration correction within a compact form factor. The aspheric profiles allow for better control of light rays without requiring increased lens curvature or additional lens elements, thus reducing total track length while improving image quality
Solution Approach 2:
The patent specifies different refractive indices and Abbe numbers for each lens element (e.g., first element: n=1.544, V=55.9; second element: n=1.634, V=33.8), creating a composite optical system that corrects chromatic and spherical aberrations more effectively than single-material systems, achieving superior aberration correction in a compact configuration
3Volume of moving object
If the lens system is made compact with limited space, then portability improves, but unnecessary light reflection and aberrations increase
Solution Approach 1:
The aspheric surfaces on all lens elements effectively control off-axis light rays and minimize spherical aberration, coma, and other off-axis aberrations that typically increase in compact systems. The precise aspheric profiles redirect stray light away from the image plane, reducing unwanted reflections and improving contrast in the compact configuration
Solution Approach 2:
The patent optimizes the axial distances between lens elements (e.g., T12=0.6mm, T23=0.4mm) and the thicknesses of individual elements to achieve compact dimensions while maintaining proper optical spacing for aberration correction. The specific refractive index selections and curvature radii are tuned to minimize internal reflections and improve light transmission in the compact form factor
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 system achieves better image quality, reduced total track length, and improved sensing efficiency by effectively correcting aberrations and minimizing unnecessary light reflection, making it suitable for high-resolution, compact imaging applications in portable devices.
Implementation Method 1
a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface
Data Source
AI summary
This invention provides an image lens system comprising: a first lens element with positive refractive power; a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface, both the object-side and image-side surfaces thereof being aspheric and made of plastic; a third lens element with positive refractive power; and a fourth lens element with negative refractive power, and at least one inflection point is formed on at least one of the object-side and image-side surfaces thereof; wherein, the region of the image-side surface of the second lens element near the optical axis is concave, but the off-axis region thereof is convex. By such arrangement, not only the photosensitivity and total track length of the system can be reduced, but also better image quality can be obtained.