Negative Lens Chromatic Aberration Correction
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Solution Overview
Problem
Existing optical systems for imaging apparatuses, such as digital cameras and video cameras, struggle to effectively correct both reference aberrations like spherical and coma aberrations, and chromatic aberrations, especially in achieving primary achromatization and secondary spectrum correction.
Innovation Solution
The optical system comprises an aperture stop and a negative lens positioned closer to the object than the aperture stop, with the negative lens satisfying specific conditional expressions regarding its refractive index, Abbe number, and partial dispersion ratio to achieve favorable correction of chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lens designs are 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 (nd), Abbe number (νd), and partial dispersion ratio (θgF) of the negative lens within specific ranges. These parameter adjustments enable effective correction of chromatic aberrations including secondary spectrum while maintaining a relatively simple lens structure with only one negative lens positioned before the aperture stop.
2Manufacturing precision
If resin material with anomalous dispersion characteristics is used, then chromatic aberrations are corrected, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for the negative lens (refractive index nd: 1.60-1.90, Abbe number νd: 20-50, partial dispersion ratio θgF: 0.530-0.600) to achieve chromatic aberration correction. By defining these parameter boundaries, the patent balances the use of resin materials with anomalous dispersion characteristics while managing manufacturing precision requirements.
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 not only reference aberrations but also chromatic aberrations, including secondary spectrum, resulting in improved image resolution and reduced color bleeding for white light sources.
Implementation Method 1
an optical system comprises an aperture stop; and a negative lens that is disposed closer to an object than the aperture stop, wherein the negative lens satisfies specific conditional expressions regarding its refractive index, Abbe number, and partial dispersion ratio
Implementation Method 2
chromatic aberrations be favorably corrected so as not to cause color bleeding for a white light source, and which have a high resolution. In particular, for correction of the chromatic aberrations, it is desirable that not only primary achromatism be achieved but also secondary spectrum be favorably corrected
Data Source
AI summary
This optical system (LS) has an aperture diaphragm (S) and a negative lens (L4) disposed closer to an object side than the aperture diaphragm (S) and satisfies the following conditional expression.−0.010<ndN1−(2.015−0.0068×νdN1),50.00<νdN1<65.00, 0.545<θgFN1,−0.010<θgFN1−(0.6418−0.00168×νdN1).Where, ndN1 is a refractive index of the negative lens with respect to a d-line,νdN1 is an Abbe number of the negative lens based on the d-line, andθgFN1 is a partial dispersion ratio of the negative lens.