Aspherical Pickup Lens Design for Compact Optical Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing pickup lenses for portable devices and cameras face challenges in achieving a short optical length while maintaining a long back focus and correcting various aberrations, leading to issues with image quality and cost, particularly due to the use of glass materials and complex lens configurations.
Innovation Solution
A pickup lens configuration using three lenses with specific refractive powers and aspherical surfaces, where the first lens has positive refractive power, the second lens has negative refractive power in a meniscus shape, and the third lens has negative refractive power, with an aperture diaphragm positioned to optimize the entrance pupil, and using plastic materials to reduce costs and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a three-element lens configuration with glass materials is used to correct aberrations and achieve short focal length, then image quality is improved, but the optical length becomes too long and manufacturing cost increases
Solution Approach 1:
The patent changes the material parameter from glass to plastic resin, which has different refractive index and dispersion characteristics. This enables achieving the same aberration correction with a shorter optical path length, resolving the contradiction between image quality and compact size
Solution Approach 2:
The patent employs aspherical surfaces on the plastic lens elements, which provide superior aberration correction compared to spherical surfaces. The aspherical shapes enable precise control of light rays, achieving high image quality in a compact configuration that would be impractical with glass materials
2Manufacturing precision
If glass materials are used for lens elements to achieve sufficient aberration correction, then image quality is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive glass materials with cheaper plastic resin materials that can be molded using injection molding techniques. This dramatically reduces manufacturing cost while maintaining adequate performance for the application, making the lens economically viable for mass production
Solution Approach 2:
The aspherical surfaces molded into the plastic lenses provide advanced aberration correction that would be costly to achieve with glass. The molding process inherently creates the complex aspherical shapes, making high-precision aberration correction affordable through plastic manufacturing
3Length of moving object
If the optical length is shortened to achieve compact lens size, then device compactness is improved, but the back focus becomes insufficient for inserting filters and cover glass
Solution Approach 1:
The patent utilizes the different optical parameters of plastic materials (refractive index, Abbe number) compared to glass to redesign the lens system. This enables achieving adequate back focus length for filter and cover glass insertion while keeping the overall optical length short, resolving the spatial conflict
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 results in a compact, cost-effective pickup lens with improved image quality by satisfying conditions that ensure a short optical length, sufficient back focus, and effective aberration correction, while maintaining a compact size and reducing material costs through the use of plastic materials.
Implementation Method 1
a first lens L1 having positive refractive power, a second lens L2 having negative refractive power, and a third lens L3 having negative refractive power
Data Source
AI summary
A pickup lens is provided with various aberrations corrected satisfactorily, with a short optical length, and with a sufficient back focus secured.The configuration comprises an aperture diaphragm S1, first lens L1, second lens L2, and third lens L3, and is configured by arranging, in order from the object side to the image side, the aperture diaphragm, first lens, second lens, and third lens. The first lens is a lens having positive refractive power, with convex surfaces on the object side and on the image side. The second lens is a lens having negative refractive power, in a meniscus shape with the convex surface on the image side. The third lens is a lens having negative refractive power, in a meniscus shape with the convex surface on the object side. Both of the surfaces of the first lens are aspherical, both of the surfaces of the second lens are aspherical, and both of the surfaces of the third lens are aspherical.