Six-Lens Image Pickup Lens with Aspherical Inflection Points
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Solution Overview
Problem
Existing image pickup lenses struggle to achieve compact size and high optical performance suitable for high-pixel-density image pickup devices, particularly in reducing aberrations such as spherical and chromatic aberration, while maintaining a small aperture and minimizing lens size and total optical length.
Innovation Solution
A six-lens configuration with specific refractive powers and aspherical surfaces, including a first positive lens, a second negative lens, a third positive lens, a fourth lens with positive or negative power, a fifth positive lens, and a sixth negative lens with aspherical surfaces having inflection points, optimized to correct various aberrations and maintain compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a five-lens configuration with a field flattener is used, then image-plane characteristics are improved, but spherical aberration and coma aberration cannot be corrected when aperture Fno is decreased
Solution Approach 1:
The patent divides the lens system into six distinct lens units with specific refractive power distributions. The sixth lens unit with negative refractive power is specifically designed to correct spherical aberration and coma aberration, separating the field flattening function (lens units 4-5) from the aberration correction function (lens unit 6), allowing both image-plane characteristics and aberration correction to be optimized independently.
Solution Approach 2:
The patent specifies precise parameter ranges for each lens unit, including refractive powers (f1, f2, f3, f4, f5, f6), focal lengths, and spacing relationships. By optimizing these parameters, particularly making the sixth lens unit have negative refractive power with specific magnitude relationships, the system achieves both good image-plane characteristics and effective aberration correction at small apertures.
2Reliability
If aperture Fno is decreased to increase shutter speed, then noise is reduced, but spherical aberration and coma aberration degradation occurs
Solution Approach 1:
The sixth lens unit serves multiple functions simultaneously: it corrects spherical aberration, corrects coma aberration, and contributes to overall image quality. This multi-functional design allows the lens to maintain good optical performance across different aperture settings, enabling noise reduction at small apertures without sacrificing aberration correction.
3Length of moving object
If lens size and total length are reduced, then compactness is improved, but chromatic aberration and Petzval sum correction become difficult
Solution Approach 1:
The patent addresses chromatic aberration and Petzval sum correction not by increasing overall lens length, but by optimizing the axial spacing and lateral positioning of lens units. The compact six-lens configuration achieves effective aberration correction through precise dimensional relationships between lens units rather than simply extending the optical path.
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 six-lens configuration effectively corrects aberrations, ensuring high optical performance and compactness suitable for high-pixel-density image pickup devices, even at smaller apertures, by optimizing the refractive powers and surface shapes of each lens.
Implementation Method 1
a sixth lens having negative refractive power and having optical surfaces, one or more of the optical surfaces each having an aspherical shape with one or more inflection points
Implementation Method 2
one or more of the optical surfaces each having an aspherical shape with one or more inflection points
Data Source
AI summary
An image pickup lens includes: in recited order from object plane toward image plane, a first lens having positive refractive power; a second lens having negative refractive power; a third lens having positive refractive power; a fourth lens having positive or negative refractive power; a fifth lens having positive refractive power; and a sixth lens having negative refractive power and having optical surfaces, one or more of the optical surfaces each having an aspherical shape with one or more inflection points.