Six-Lens Imaging System Aberration Control
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Solution Overview
Problem
Conventional imaging lenses for small cameras face challenges in achieving both downsizing and satisfactory aberration correction, particularly in smartphones and other portable devices, where high resolution and wide angles are required while maintaining a compact form factor.
Innovation Solution
The imaging lens configuration includes a specific arrangement of lenses with varying refractive powers and curvature radii, with the first and second lenses having strong refractive power for initial aberration correction, and the third to sixth lenses providing finer corrections, along with aspheric shapes for the fifth and sixth lenses to manage off-axis aberrations, and adherence to specific conditional expressions to optimize focal lengths and Abbe's numbers for effective aberration control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of lenses is increased to improve aberration correction, then aberration correction performance is improved, but the size of the imaging lens increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive indices (nd1=1.46-1.60, nd2=1.60-1.75, nd3=1.50-1.65) and Abbe's numbers (vd1=30-60, vd2=20-40, vd3=30-50) of each lens element, along with specific curvature radii and thickness parameters. This allows six lenses to achieve superior aberration correction while maintaining a compact form factor, resolving the contradiction between correction performance and size.
Solution Approach 2:
The patent uses composite lens structures with different glass materials having specific refractive index and Abbe's number combinations. The first lens group uses materials with lower refractive index and higher Abbe's number, while the second lens group uses materials with higher refractive index and lower Abbe's number, creating a composite system that corrects both spherical and chromatic aberrations efficiently in a compact design.
2Volume of moving object
If the focal length is reduced to downsize the imaging lens, then the size is reduced, but the angle of view becomes narrower
Solution Approach 1:
The patent employs aspheric surfaces on the first, fourth, and sixth lenses, which introduces a dimensional change from spherical to aspheric geometry. This allows the lens system to achieve a wide angle of view (60° or more) with a reduced focal length (4.0mm or less) by controlling light rays in multiple dimensions, resolving the contradiction between downsizing and maintaining wide angle capability.
3Device complexity
If the refractive power of lenses is increased to reduce the number of lenses, then the lens count is reduced, but aberration correction performance deteriorates
Solution Approach 1:
The patent segments the imaging lens into six distinct lens elements with alternating positive and negative refractive powers. Each lens element is optimized with specific material properties and geometric parameters, allowing the system to achieve comprehensive aberration correction through distributed correction across multiple segments rather than relying on a single high-power element.
Solution Approach 2:
The patent applies local quality by assigning different material properties to different lens elements: the first lens uses low refractive index/high Abbe's number material for controlling spherical aberration, the second lens uses high refractive index/low Abbe's number material for chromatic aberration correction, and subsequent lenses are optimized for their specific positions in the optical path, achieving superior overall correction.
4Volume of moving object
If the distance from the first lens to the image plane is reduced to downsize the camera, then the camera size is reduced, but the optical path must be bent requiring additional components
Solution Approach 1:
The patent achieves a short back focal length (0.5mm or less) by dynamically optimizing the positions and powers of all six lens elements, allowing the optical system to maintain a compact distance from the first lens to the image plane without requiring optical path bending components, thus resolving the contradiction between camera downsizing and optical path simplicity.
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 allows for balanced aberration correction, achieving both downsizing and high-resolution imaging capabilities suitable for small cameras, while preventing issues like shading and distortion, and ensuring satisfactory image-forming performance across different wavelengths.
Implementation Method 1
a first lens having positive refractive power
Implementation Method 2
a second lens having negative refractive power
Implementation Method 3
a fourth lens having negative refractive power
Implementation Method 4
a fifth lens having positive refractive power
Data Source
AI summary
An imaging lens includes a first lens having positive refractive power; a second lens having negative refractive power; a third lens; a fourth lens having negative refractive power; a fifth lens having positive refractive power; and a sixth lens, arranged in this order from an object side to an image plane side. The first lens is formed so that a surface thereof on the object side has a positive curvature radius. The sixth lens is formed so that a surface thereof on the object side and a surface thereof on the image plane side have positive curvature radii. Each of the first to sixth lenses has an Abbe's number within a specific range.