Negative Lens Chromatic Aberration Correction via Parameter Control
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Solution Overview
Problem
Current optical systems for imaging apparatuses, such as digital cameras, face challenges in effectively correcting chromatic aberrations, particularly secondary spectrum, in addition to primary achromatization, which affects image quality and color fidelity.
Innovation Solution
The optical system incorporates a negative lens with specific refractive index and Abbe number characteristics, defined by conditional expressions, to optimize chromatic aberration correction, including primary achromatization and secondary spectrum correction, and is designed with a configuration that allows for zooming or focusing by adjusting the distance between lens groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional lens design is used, then the structure is simple, but chromatic aberrations including secondary spectrum cannot be effectively corrected
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive index (ndN2, ndN4) and Abbe number (νdN2, νdN4) of the negative lenses, along with their partial dispersion ratios (θgFN2, θgFN4). By adjusting these optical parameters within specific ranges defined by conditional expressions, the patent achieves effective correction of chromatic aberrations including secondary spectrum, while maintaining a relatively simple lens structure.
2Manufacturing precision
If resin material with anomalous dispersion characteristics is used, then chromatic aberration correction is improved, but manufacturing precision and material consistency become more difficult to control
Solution Approach 1:
The patent specifies precise parameter ranges for resin materials including refractive index (ndN2: 1.450-1.650, ndN4: 1.500-1.700), Abbe number (νdN2: 20.0-40.0, νdN4: 25.0-45.0), and partial dispersion ratio (θgFN2: 0.530-0.570, θgFN4: 0.540-0.580). By controlling these parameters within defined ranges, the patent achieves effective chromatic aberration correction while maintaining manufacturability and material consistency.
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 solution achieves improved image quality by effectively correcting chromatic aberrations, including secondary spectrum, leading to enhanced resolution and color fidelity across various focal lengths and lighting conditions.
Implementation Method 1
an optical system includes: an aperture stop; and a negative lens that is disposed closer to an image than the aperture stop, wherein the negative lens satisfies the following conditional expressions: −0.010<ndN2−(2.015−0.0068×νdN2)...<50.00<dN2/gFN2...<−0.010<gFN2−(0.6418−0.00168×νdN2)
Data Source
AI summary
An optical system (LS) has an aperture stop (S), and a negative lens (L73) disposed closer to the image side than the aperture stop (S) and satisfying the following conditional expressions.−0.010<ndN2−(2.015−0.0068×νdN2),50.00<νdN2<65.00,0.545<θgFN2,−0.010<θgFN2−(0.6418−0.00168×νdN2)where ndN2 is the refractive index to the d line of the negative lens, νdN2 is the Abbe number with respect to the d line of the negative lens, and θgFN2 is the partial dispersion ratio of the negative lens.