Five-Element Lens Aberration Correction via Radial Power Gradient

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Solution Overview

Problem

Current image capturing lenses face challenges in achieving high resolution and reduced overall length while effectively correcting longitudinal chromatic aberration and distortion, especially in peripheral regions, particularly for high pixel count image sensors.

Innovation Solution

A five-element lens configuration with specific refractive powers and shapes for each lens element, including a convex first lens, negative second and third lenses, a concave fourth lens, and a fifth lens with gradually reduced negative refractive power, optimized to balance powers and correct aberrations, is employed, with conditional expressions defining the optimal ratios and configurations for improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a five-lens configuration is employed to reduce overall length and improve resolution, then the compactness and resolution are improved, but the correction of longitudinal chromatic aberration and peripheral aberrations becomes insufficient

Engineering Contradiction:

Improveoverall lengthVSAvoidaberration correction

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The fifth lens is designed with spatially varying refractive power, where the negative refractive power is gradually reduced outwardly in the radial direction from the optical axis. This local variation in optical properties allows the lens to correct both longitudinal chromatic aberration and peripheral aberrations effectively while maintaining a compact five-lens configuration.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent optimizes specific parameter ranges including the focal length ratio (4.2 < f3/f1 < 6.0), the refractive index and Abbe number combinations of lens materials, and the curvature radii of lens surfaces. These parameter optimizations enable sufficient aberration correction while maintaining reduced overall length.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the focal lengths of the first and third lenses are optimized to balance their powers, then various aberrations including spherical aberration and astigmatism are corrected satisfactorily, but the overall length reduction becomes more challenging

Engineering Contradiction:

Improveaberration correctionVSAvoidoverall length

Core Design Contradiction:

Manufacturing precisionVSVolume of moving object

Solution Approach 1:

The patent establishes an optimal range for the focal length ratio between the third and first lenses (4.2 < f3/f1 < 6.0). This parameter optimization balances the positive refractive powers of these lenses, enabling effective correction of spherical aberration and astigmatism while coordinating with the overall compact design through the negative power lenses.

Inventive Principle:

Principle #35Parameter changes

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 achieves high image forming performance from central to peripheral angles of view with reduced overall length, effectively correcting spherical aberration, astigmatism, and chromatic aberration, enabling high-resolution image capture.

Implementation Method 1

a first lens having a positive refractive power with the object side surface being formed in a convex shape toward the object side

Methodology Applied