Five-Lens Imaging System with Aspherical Fifth Element
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Solution Overview
Problem
Existing imaging lenses for digital devices with high pixel counts and large image sensors face challenges in achieving a short total length, wide angle of view, small F number, and high imaging performance, as they tend to become excessively long and fail to adequately correct aberrations.
Innovation Solution
A five-lens imaging lens configuration with specific refractive powers and shapes, including a first lens with positive refractive power and convex surface, a second lens with negative refractive power and meniscus shape, a third lens with positive refractive power and meniscus shape, a fourth lens with positive refractive power and concave surface, and a fifth lens with negative refractive power and aspherical surface, optimized to satisfy conditional formulas for focal length, total length, and angle of view, while incorporating aspherical surfaces and an aperture stop to enhance optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of lenses is increased to five lenses configuration, then imaging performance and resolution are improved, but the total length of the lens becomes excessively long
Solution Approach 1:
The patent applies parameter changes by optimizing the refractive powers, curvatures, and spacing of each lens element. Specifically, it uses conditional formulas relating focal lengths (f/f1, f/f3, f/f5) and structural parameters (TTL/(f·tanω)) to achieve high imaging performance with a compact total length. The aspherical surface parameters are also optimized to correct aberrations while maintaining short length.
Solution Approach 2:
The patent employs aspherical surfaces on the fifth lens to correct optical aberrations more effectively than spherical surfaces. The aspherical shape allows for better control of light rays at wide angles while maintaining a shorter overall lens length, resolving the contradiction between imaging performance and compact size.
2Manufacturing precision
If the image size of imaging element is increased to accommodate more pixels, then resolution is improved, but the total length of lens must be shortened
Solution Approach 1:
The patent optimizes multiple parameters simultaneously including the focal lengths of individual lenses (f1, f3, f5), the total length to image height ratio (TTL/(f·tanω)), and the aspherical surface coefficients. This multi-parameter optimization enables the lens to achieve high resolution for large image sensors while maintaining a short total length suitable for portable devices.
Solution Approach 2:
The five-lens configuration divides the optical system into multiple segments, each with specific refractive powers and functions. This segmentation allows for better control of aberrations across the image field and enables compact design by distributing optical functions across multiple elements rather than requiring a single long lens.
3Manufacturing precision
If the angle of view is widened and F number is reduced, then imaging performance is improved, but aberration correction becomes more difficult
Solution Approach 1:
The aspherical surface on the fifth lens is specifically designed to correct aberrations at wide angles of view. The aspherical shape provides additional degrees of freedom for controlling off-axis light rays, enabling effective correction of coma, astigmatism, and distortion that would be difficult to correct with spherical surfaces alone in a wide-angle, small F-number design.
Solution Approach 2:
Different lens elements are assigned different refractive powers and surface curvatures tailored to their specific functions in the optical path. The fifth lens with its aspherical surface specifically addresses wide-angle aberrations, while other lenses handle different aspects of image formation, allowing effective aberration correction across the entire field without excessive complexity.
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 configuration achieves a shortened total length compatible with high pixel counts, wider angles of view, and high imaging performance from central to peripheral angles, effectively addressing the limitations of previous lens designs by optimizing each lens element's shape and position within the lens system.
Implementation Method 1
a fifth lens having a negative refractive power and is of a meniscus shape having a convex surface toward the object side, the surface thereof toward the image side being of an aspherical shape
Data Source
AI summary
An imaging lens is substantially constituted by five lenses, including: a positive first lens having a convex surface toward the object side; a negative second lens of a meniscus shape with a concave surface toward the object side; a positive third lens of a meniscus shape with a convex surface toward the object side; a positive fourth lens of a meniscus shape with a concave surface toward the object side; and a negative fifth lens having a concave surface toward the image side, the surface thereof toward the image side being of an aspherical shape having at least one inflection point within a range from an intersection of a principal light ray at a maximum angle of view with the surface toward the image side inwardly toward the optical axis in the radial direction, provided in this order from the object side. The imaging lens satisfies a predetermined conditional formula.