Imaging Lens Aberration Correction via Refractive Power Inversion
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Solution Overview
Problem
Conventional imaging lenses for small cameras face challenges in achieving both miniaturization and effective aberration correction due to their relatively long focal length, which makes it difficult to reduce the optical axis distance from the first lens to the image plane, leading to insufficient aberration correction and size constraints.
Innovation Solution
The imaging lens configuration consists of a first meniscus lens, a second biconcave lens, and a third meniscus lens, with specific focal length and curvature radius relationships that satisfy conditional expressions to reduce thickness while optimizing aberration correction, including spherical aberration, chromatic aberration, and astigmatism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional three-lens configuration is used with the first lens having stronger refractive power than the second lens, then aberration correction is improved, but the focal length becomes relatively long making miniaturization difficult
Solution Approach 1:
The patent inverts the refractive power relationship between lenses: the second lens (negative power) now has stronger magnitude than the first lens (positive power), satisfying |f2| < f1. This parameter inversion allows achieving both compact focal length and proper aberration correction by changing the power distribution while maintaining the three-lens structure.
Solution Approach 2:
The conventional design principle is inverted: instead of the first lens having stronger positive power than the second lens has negative power, the patent makes the second lens have stronger negative power than the first lens has positive power. This inversion enables compact focal length while maintaining aberration correction capability.
2Length of moving object
If the focal length is reduced for miniaturization, then the lens size is improved, but the ability to properly correct aberration deteriorates
Solution Approach 1:
By changing the refractive power parameters to satisfy |f2| < f1, the patent achieves a shorter effective focal length for miniaturization while the specific power distribution maintains the capability to correct various aberrations including spherical aberration, coma, and astigmatism through the coordinated action of the three lenses.
Solution Approach 2:
The patent uses composite lens materials with different refractive indices and Abbe numbers (e.g., LD and HD materials) to achieve both compact size and proper aberration correction. The combination of materials with different optical properties enables simultaneous control of focal length and chromatic aberration.
3Device complexity
If the second lens has weaker negative refractive power, then the lens configuration is simpler, but the refractive power distribution cannot achieve optimal compactness and aberration correction
Solution Approach 1:
The patent optimizes the refractive power parameter of the second lens to satisfy |f2| < f1, creating a specific power distribution that achieves optimal compactness. This parameter optimization allows the optical axis distance to be reduced while maintaining proper aberration correction, balancing simplicity and 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 allows for a smaller imaging lens size with improved aberration correction, maintaining image flatness and reducing thickness, thereby achieving both miniaturization and effective aberration correction.
Implementation Method 1
a first lens having positive refractive power; a second lens having negative refractive power; and a third lens having positive refractive power arranged in an order from an object side to an image side
Data Source
AI summary
An imaging lens includes a first lens L1 having positive curvature radii on both an object side and an image side, a second lens L2 having a concave shape on both sides, and a third lens L3 having positive curvature radii on both the object side and the image side. The first to third lenses L1 to L3 are arranged in this order from the object side toward the image side. When the first lens L1 has a focal length f1 and the second lens L2 has a focal length f2, the imaging lens is configured such that a relationship f1>|f2| is satisfied.