Aspherical Lens Array for Contact Image Sensor Aberration
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Solution Overview
Problem
Conventional lens arrays for erecting unit magnification systems suffer from significant optical aberration, leading to reduced MTF performance, especially for contact image sensors, where pixels off the optical axis are shifted due to aberration, resulting in lower image formation quality.
Innovation Solution
The solution involves stacking two planar-shaped lens array plates with regularly arranged first and second inside lenses of aspherical shape, and outside lenses of aspherical shape, ensuring coaxial alignment to minimize optical aberration and enhance MTF performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spherical shape lenses are used for inside lenses and spherical or aspherical shape lenses are used for outside lenses in conventional lens arrays, then the lens array can be manufactured with standard molding techniques, but optical aberration increases significantly leading to reduced MTF performance
Solution Approach 1:
The patent applies parameter changes by transitioning from spherical to aspherical lens shapes for the inside lenses. This changes the geometric parameter of the lens surface curvature to eliminate optical aberration while maintaining manufacturability through injection molding techniques. The aspherical shape parameter is specifically designed to correct off-axis optical distortion.
Solution Approach 2:
The patent applies local quality by differentiating the lens shape requirements between inside lenses and outside lenses. Inside lenses are designed with aspherical shapes to correct optical aberration, while outside lenses can use spherical or aspherical shapes. This localized optimization ensures that each lens region performs its specific function optimally without compromising overall manufacturability.
2Power
If planar-shaped lens array plates are stacked with micro convex lenses to form erecting unit magnification system, then the system achieves image magnification and focusing, but optical aberration causes pixel shift especially for off-optical axis pixels
Solution Approach 1:
The patent changes the lens shape parameter from spherical to aspherical for inside lenses to correct optical aberration that causes pixel shift. This parameter change maintains the magnification function while improving pixel position accuracy for both on-axis and off-axis pixels.
Solution Approach 2:
The patent applies spheroidality by using aspherical curvature instead of spherical curvature for inside lenses. The aspherical surface geometry correctly focuses light rays from off-axis points, eliminating the pixel shift problem while preserving the image magnification capability of the erecting unit.
3Manufacturing precision
If aspherical shape inside lenses are used to reduce optical aberration, then MTF performance improves significantly, but lens manufacturing complexity increases
Solution Approach 1:
The patent changes the lens shape parameter to aspherical form, which improves optical performance and MTF. While this increases design complexity, the patent maintains manufacturability by using standard injection molding techniques that can accommodate aspherical surfaces through proper mold design.
Solution Approach 2:
The patent uses copying by creating precise aspherical surface replicas through injection molding. The mold captures the complex aspherical geometry and reproduces it consistently across multiple lenses, making the manufacturing process scalable despite the increased geometric complexity.
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 reduces optical aberration, improving the MTF performance and maintaining high optical resolution across the optical axis and off-axis viewing angles, thereby enhancing the overall image formation quality.
Implementation Method 1
each of the first and second inside lenses has a first aspherical shape so as to decrease the optical aberration of on-optical axis and off-optical axis
Implementation Method 2
The light 14a obtained from a light-emitting point 11 is focused through the lens array 10 of the erecting unit magnification system on a focusing point 12
Data Source
AI summary
The conventional lens array of an erecting unit magnification system is composed of an inside lens of spherical shape and an outside lens of spherical or aspherical shape, and has a problem to be improved for the resulting MTF performance. A lens array of an erecting unit magnification system is provided by stacking a first and a second planar-shaped lens array plates. Each of the first and second planar-shaped lens array plates includes a plurality of outside lenses (L1 and L4), which are regularly arranged on one side thereof, and a plurality of inside lenses (L2 and L3), which are regularly arranged on the other side thereof. Especially, the outside lenses (L1 and L4) and the inside lenses (L2 and L3) are formed based on the defining method according to the present invention.