Imaging Lens Aberration Correction via Alternating Refractive Power
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Solution Overview
Problem
The challenge is to develop a miniaturized compact imaging lens for mobile phone camera modules that maintains high resolution, as existing lenses face difficulties in achieving both miniaturization and high image quality due to limitations in refractive power and lens configuration.
Innovation Solution
The proposed solution involves a configuration of four lenses with specific refractive powers and shapes, 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, meeting certain conditional expressions to optimize focal lengths, radii of curvature, and refractive indices, resulting in a compact and high-resolution imaging lens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of lenses is increased to improve image quality and aberration correction, then the resolution and aberration performance are improved, but the overall size and complexity of the lens system increase
Solution Approach 1:
The imaging lens is divided into four distinct lens elements with alternating positive and negative refractive powers. Each lens element is optimized for specific aberration correction functions, allowing the system to achieve high image quality while maintaining a manageable configuration. The segmentation of functions across four elements resolves the contradiction by providing sufficient complexity for quality improvement without excessive overall system complexity.
Solution Approach 2:
Each lens element is designed with specific local optical properties - the first and third lenses have positive refractive power for convergence, while the second and fourth lenses have negative refractive power for divergence and aberration correction. This local differentiation of optical characteristics allows each element to contribute specifically to overall image quality without requiring uniform complexity across all elements, thus improving image quality while controlling system complexity.
2Length of moving object
If the lenses are positioned closely together to miniaturize the imaging lens, then the overall size is reduced, but the manufacturing precision and alignment requirements increase
Solution Approach 1:
The four lens elements are merged into a compact arrangement where the total length is minimized by optimizing the spacing between elements. The conditional expression D4-D3≤0 mathematically defines the maximum allowable spacing, ensuring that the lenses are positioned closely enough to achieve miniaturization while maintaining sufficient precision for proper optical function. This merging approach resolves the contradiction by achieving compact size through controlled close positioning.
Solution Approach 2:
The patent employs aspherical surfaces on the lens elements, which changes the geometric parameters from traditional spherical shapes. This parameter change allows for more flexible positioning and spacing between lenses, enabling closer arrangement for miniaturization while the aspherical profiles compensate for alignment tolerances, thus reducing the stringent precision requirements that would normally accompany close positioning.
3Length of moving object
If the refractive power of individual lenses is increased to reduce focal length and miniaturize the system, then the compactness is improved, but the aberration performance deteriorates
Solution Approach 1:
The imaging lens uses alternating positive and negative refractive power elements where the negative power elements (second and fourth lenses) act as counterweights to the positive power elements (first and third lenses). This counterbalancing approach allows the positive elements to provide the necessary converging power for miniaturization while the negative elements correct the aberrations introduced by high refractive power, thus achieving both compact focal length and good aberration performance simultaneously.
Solution Approach 2:
The lens system combines different types of lens elements with varying refractive indices and dispersion characteristics. The composite structure of four different lens elements, each with optimized refractive properties, allows the system to achieve high converging power for miniaturization while the diverse optical characteristics of the composite elements work together to correct various types of aberrations, resolving the contradiction between compact focal length and aberration performance.
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
This configuration enables a super small-sized camera module with improved coma aberration correction and aberration performance, achieving excellent lens characteristics by closely positioning the lenses and optimizing their refractive properties, thus enhancing image quality and miniaturization.
Implementation Method 1
a first lens having positive (+) refractive power
Implementation Method 2
a second lens having negative (−) refractive power
Implementation Method 3
a third lens having positive (+) refractive power
Implementation Method 4
a fourth lens having negative (−) refractive power
Data Source
AI summary
An exemplary embodiment of the present invention relates to an imaging lens, the imaging lens including, in an ordered way from an object side, a first lens having positive (+) refractive power, a second lens having negative (−) refractive power, a third lens having positive (+) refractive power, a fourth lens having negative (−) refractive power, wherein the imaging lens meets a conditional expression of D4−D3≦0, where D3 is a distance from an apex of an object side surface of the third lens to an apex of an image side surface of the third lens, and D4 is an axial distance from the apex of an object side surface of the third lens to an effective diameter of an object side surface of the fourth lens.