Eight-Lens Imaging System Aberration Correction via Parameter Optimization
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Solution Overview
Problem
Existing imaging lenses struggle to achieve a small F-number while maintaining high optical performance and effectively correcting various aberrations, as seen in the limitations of the lens system disclosed in JP5830638B.
Innovation Solution
An imaging lens configuration comprising eight lenses with specific refractive powers and curvatures, including a negative and positive lens arrangement, where conditional expressions are satisfied to correct aberrations and achieve a small F-number, such as νd5 < 23, 0.8 < Db23/f < 7, and 3 < f456/f < 28, ensuring high optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a lens system with 6-8 lenses is used to reduce size, then the number of lenses is minimized, but the F-number cannot be made small enough and optical performance deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the Abbe number of the fifth lens (νd5) within the range 16 < νd5 < 23, and by setting specific relationships between focal lengths (f1/f, f2/f, f3/f) and distances (Db23/f, Dc34/f). These parameter optimizations enable the 6-8 lens system to achieve both small size and high optical performance with small F-number, resolving the contradiction between miniaturization and performance maintenance.
2Device complexity
If the number of lenses is reduced to 6-8, then device complexity is lowered, but the ability to correct various aberrations is insufficient
Solution Approach 1:
The patent applies local quality by assigning specific functional characteristics to individual lenses within the 6-8 lens system. The fifth lens is specifically designed with a controlled Abbe number (16 < νd5 < 23) to address chromatic aberration, while other lenses have specific focal length relationships (f1/f, f2/f, f3/f) optimized for their respective aberration correction tasks. This localized optimization of each lens's properties enables effective aberration correction despite the reduced total number of lenses.
3Use of energy by moving object
If lens parameters are optimized for small F-number, then light gathering ability improves, but aberration correction becomes difficult
Solution Approach 1:
The patent resolves this contradiction through comprehensive parameter optimization: setting the Abbe number of the fifth lens within 16 < νd5 < 23, establishing focal length relationships (0.3 < f1/f < -0.1, 0.4 < f2/f < 0.8, -0.8 < f3/f < -0.2), and controlling distance ratios (0.8 < Db23/f < 7, 2 < Dc34/f < 15). These coordinated parameter settings enable the system to achieve small F-number for improved light gathering while simultaneously maintaining effective 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
The proposed lens configuration achieves a small F-number and high optical performance by satisfactorily correcting various aberrations, particularly longitudinal chromatic aberration, distortion, and spherical aberration, while reducing the lens system's size and improving resolution.
Implementation Method 1
Assuming that an Abbe number of the fifth lens at a d line is νd5, Conditional Expression (1) is satisfied, which is represented by 16 < νd5 < 23
Implementation Method 2
only eight lenses consisting of, in order from an object side to an image side, a first lens that has a negative refractive power, a second lens that has a negative refractive power, a third lens that has a positive refractive power and of which an image side surface is convex
Data Source
AI summary
The imaging lens includes only eight lenses consisting of, in order from an object side, a negative first lens, a negative second lens, a positive third lens convex toward an image side, a positive fourth lens convex toward an object side, a negative fifth lens, a positive sixth lens convex toward the image side, a positive seventh lens convex toward the object side, and a negative eighth lens, as lenses having refractive powers, in which predetermined conditional expressions are satisfied.