Compact Imaging Optical System with Aspherical Lens for Chromatic Aberration Correction
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Solution Overview
Problem
Existing imaging optical systems for digital cameras and cellular phones face challenges in minimizing size while maintaining adequate optical performance, particularly in aberration correction such as chromatic aberration.
Innovation Solution
The proposed imaging optical system consists of three lenses with specific power configurations and aspherical surfaces, where the second lens has a high dispersion characteristic and the third lens has a low dispersion characteristic, with Abbe numbers satisfying certain relationships to correct chromatic aberration, and includes a diaphragm to balance aberrations, allowing for a compact design with improved optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If three lenses are used to minimize the size of the imaging optical system, then the size is reduced, but the aberration correction, such as chromatic aberration, is insufficient
Solution Approach 1:
The patent changes the parameters of the lens system by introducing a specific lens configuration with a third lens having negative power and an aspherical surface. The aspherical surface parameter k is set to satisfy -1 < k < 0, which fundamentally alters the optical characteristics and enables effective chromatic aberration correction while maintaining a compact three-lens structure.
Solution Approach 2:
The patent applies an aspherical surface to the third lens instead of a conventional spherical surface. The aspherical surface with parameter k between -1 and 0 provides superior aberration correction capabilities, particularly for chromatic aberration, while maintaining the compact size of the three-lens system.
2Device complexity
If a three-lens configuration is used to reduce size, then the device complexity is reduced, but the optical performance in terms of aberration correction deteriorates
Solution Approach 1:
The patent optimizes the parameters of the three-lens configuration, specifically setting the third lens with negative power and an aspherical surface where -1 < k < 0. This parameter optimization enables the simple three-lens structure to achieve adequate aberration correction without adding complexity.
Solution Approach 2:
The patent employs a composite lens structure combining three lenses with different power characteristics (first lens: positive power, second lens: positive power, third lens: negative power). This composite configuration achieves balanced aberration correction while maintaining structural simplicity.
3Volume of moving object
If the imaging optical system is made smaller, then the size is minimized, but the optical performance and image quality deteriorate
Solution Approach 1:
The patent introduces an aspherical surface on the third lens with parameter k satisfying -1 < k < 0. This aspherical curvature provides enhanced aberration correction capabilities that maintain high image quality even in a compact three-lens configuration, preventing the size reduction from degrading optical performance.
Solution Approach 2:
The patent optimizes the optical parameters of the compact system by setting specific conditions on the lens powers and the aspherical surface parameter k. These parameter adjustments ensure that the small three-lens structure achieves adequate image quality and aberration correction.
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 effectively corrects chromatic aberration and other optical distortions, ensuring high image quality across the image surface while maintaining a small size and low manufacturing costs, suitable for various camera applications.
Implementation Method 1
a third lens with negative power on an image side of the second lens, an image side surface of the third lens being aspherical
Implementation Method 2
the aberration of which, such as chromatic aberration having been appropriately corrected
Data Source
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Figure 3~4
Figure 5(A)~6(C)
AI summary
An imaging optical system, which is designed in a small size with low manufacturing costs, aberrations such as chromatic aberration of the imaging optical system being appropriately corrected, is provided. The imaging optical system comprises a first lens having positive power, a second lens having positive power and a third lens having negative power with an aspherical surface in the image side, the aspherical surface being shaped in a concave shape facing toward an image side in a vicinity of the optical axis and shaped in a convex shape facing toward the image side in a surrounding of the optical axis. The imaging optical system is designed to satisfy a formula, v3 - v2 > 10, where v3 denotes an Abbe number of the third lens and v2 denotes an Abbe number of the second lens.