Imaging Lens Aberration Correction via Segmented Front Rear Groups
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Solution Overview
Problem
Conventional imaging lenses used in endoscopes and cameras suffer from insufficient correction of various aberrations, leading to suboptimal image quality.
Innovation Solution
The proposed imaging lens system consists of a front group with negative refractive power and a rear group with positive refractive power, including specific cemented lenses and an aperture stop configuration, which satisfies certain conditional formulas to effectively correct aberrations, ensuring high image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lens systems (front group, aperture stop, rear group) are used, then the structure is simple, but aberration correction is insufficient
Solution Approach 1:
The lens system is divided into a front group and a rear group with specific configurations. The front group includes a first negative lens and a second negative lens, while the rear group includes a positive lens and a negative lens, with an aperture stop positioned between them. This segmentation allows each group to be optimized for specific aberration corrections, achieving superior overall performance.
Solution Approach 2:
Each lens element is assigned a specific refractive power and Abbe number to address particular aberration issues. The first negative lens has a specific focal length ratio to the entire system, the second negative lens has a different Abbe number, the positive lens has a controlled Abbe number range, and the negative lens in the rear group has a specific focal length ratio. This local optimization of optical properties enables precise correction of various aberrations throughout the system.
2Manufacturing precision
If more lens elements are added to improve aberration correction, then image quality improves, but lens system length increases
Solution Approach 1:
The patent specifies precise parameter ranges for each lens element to achieve optimal aberration correction within a compact form factor. The first negative lens has a focal length ratio of -0.35 < f1/f < -0.15, the second negative lens has an Abbe number of 20 < νd2 < 50, the positive lens has 30 < νd3 < 80, and the negative lens in the rear group has a focal length ratio of -3.0 < f4/f < -1.0. These controlled parameter variations enable effective aberration correction while maintaining a compact lens system length.
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 significantly improves the correction of aberrations, resulting in high-quality images with increased back focus, reduced lens system length, and suppression of chromatic and spherical aberrations, suitable for applications in endoscopes and cameras.
Implementation Method 1
a first cemented lens formed by cementing a negative lens and a positive lens having a smaller Abbe's number with respect to the d line (wavelength: 587.6 nm) than the negative lens
Data Source
AI summary
An imaging lens is constituted by, in order from the object side to the image side: a front group having a negative refractive power; and a rear group having a positive refractive power. The front group is constituted by two negative lenses. The rear group includes a cemented lens formed by cementing a negative lens and a positive lens having a smaller Abbe's number with respect to the d line (wavelength: 587.6 nm) than the negative lens, provided in this order from the object side to the image side, together.