Five-Lens Plastic Imaging Lens with Diffraction Surface
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Solution Overview
Problem
Current imaging lenses face challenges in achieving a high aperture ratio, correcting chromatic and other aberrations, while being compact and cost-effective, especially with the increasing pixel size and complexity of imaging elements in portable devices.
Innovation Solution
A five-lens configuration with aspheric surfaces, including a diffraction optics surface on the second lens for chromatic dispersion, and all lenses made from plastic material, optimized to correct chromatic aberration and other aberrations, with specific focal length ratios to achieve a large aperture ratio and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If glass material is used for lens elements, then chromatic aberration correction is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the material parameter from glass to plastic, and compensates for the reduced chromatic aberration correction capability by optimizing the diffraction optics surface parameters and lens configuration. This allows cost reduction while maintaining imaging performance.
Solution Approach 2:
The patent replaces the material-based chromatic aberration correction (glass) with a surface-based correction mechanism (diffraction optics surface with specific aspheric coefficients and optical path difference function), enabling plastic material usage without sacrificing correction performance.
2Illumination intensity
If aperture ratio is increased to F/2.4 or larger, then light gathering capability is improved, but aberration correction becomes more difficult
Solution Approach 1:
The patent employs aspheric surfaces on all lens elements with specifically optimized aspheric coefficients. This curvature variation allows the lens to maintain aberration correction performance even with the large aperture ratio of F/2.4 or larger, as the aspheric shapes compensate for the increased spherical and coma aberrations.
Solution Approach 2:
The patent uses plastic material combined with diffraction optics surface structure to achieve both large aperture ratio and aberration correction. The composite approach of material + surface structure enables performance that neither alone could achieve at such large apertures.
3Manufacturing precision
If five-lens configuration is used, then aberration correction is improved, but device complexity increases
Solution Approach 1:
The patent divides the imaging lens into five distinct lens elements, each with specific optical powers and aspheric surface characteristics. This segmentation allows independent optimization of each element to correct different types of aberrations, achieving superior correction performance while managing complexity through modular design.
Solution Approach 2:
Each lens element in the five-lens configuration serves multiple functions: the first lens group handles spherical aberration and coma, the second group addresses astigmatism, the third group corrects field curvature, and the fourth and fifth groups refine chromatic and lateral color corrections. This multi-functionality reduces the need for additional elements.
4Productivity
If pixel size is reduced to increase pixels, then imaging element density is improved, but light receiving area decreases
Solution Approach 1:
The patent changes the aperture ratio parameter to F/2.4 or larger, significantly increasing the light gathering capability. This parameter change compensates for the reduced light receiving area of smaller pixels, ensuring sufficient illumination intensity even as pixel density increases.
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 corrects chromatic and other aberrations, achieving a high-performance, compact imaging lens with a large aperture ratio, suitable for small-sized imaging elements in portable devices, while reducing costs by using plastic materials.
Implementation Method 1
a diffraction optics surface exerting chromatic dispersion function is arranged on a surface on an image side of the second lens
Data Source
AI summary
An imaging lens with large aperture ratio, high-performance and low-cost is provided, which is applied to an imaging element of a small-size and high resolution, in which aberration is corrected satisfactorily and sufficient diffraction resolution is achieved. An imaging lens includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged in sequence from an object side, wherein both surfaces of each lens are formed from aspheric surface, a diffraction optics surface exerting chromatic dispersion function is arranged on a surface on an image side of the second lens, each lens is configured from plastic material, and an aperture ratio is equal to or smaller than F/2.4.