Asymmetrical Microlenses for Uniform Light Capture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image sensor technologies face issues with light capture efficiency due to the small size of microlenses relative to pixels and degradation in image quality when incident light angles vary, particularly for asymmetrical pixel arrangements.
Innovation Solution
The use of asymmetrical microlenses with a truncated hemisphere shape, where the optical axis is aligned with the photodiode, allowing for uniform light distribution across asymmetrical pixel arrays, even at varying angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If microlenses are positioned spanning and centered over the photodiodes in asymmetrical pixel arrangements, then the light gathering capacity is improved, but the uniformity of light distribution degrades when incident light angles vary
Solution Approach 1:
The microlenses are designed with asymmetrical shapes that correspond to the asymmetrical arrangement of photodiodes within pixels. Each microlens has a tailored geometry that compensates for the non-uniform spatial distribution of photodiodes, ensuring that light is focused uniformly onto the photodiode surfaces regardless of incident angle. This asymmetry principle transforms the problematic pixel layout into an advantage by customizing the optical path for each pixel location.
Solution Approach 2:
Each microlens is customized with specific local geometric properties that match the local photodiode arrangement in its corresponding pixel. The microlens shape, size, and positioning are locally optimized for each pixel's specific photodiode configuration, rather than using a uniform design across all pixels. This local quality approach ensures optimal light distribution performance for each individual pixel's unique geometry.
2Device complexity
If microlenses are made small to fit within pixel areas, then the device complexity is reduced, but the light gathering capacity decreases
Solution Approach 1:
The microlens design extends into the vertical dimension with optimized curvature and depth profiles that increase light gathering capacity without increasing lateral footprint. By utilizing the third dimension (lens depth and curvature) rather than only lateral expansion, the design captures more incident light while maintaining compatibility with standard pixel pitch and avoiding increased device complexity.
3Productivity
If photodiodes are arranged asymmetrically to maximize pixel performance, then the productivity is improved, but artifacts occur when incident angle of illumination varies
Solution Approach 1:
The microlenses are designed with asymmetrical shapes that correspond to the asymmetrical arrangement of photodiodes within pixels. Each microlens has a tailored geometry that compensates for the non-uniform spatial distribution of photodiodes, ensuring that light is focused uniformly onto the photodiode surfaces regardless of incident angle. This asymmetry principle transforms the problematic pixel layout into an advantage by customizing the optical path for each pixel location.
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 solution enhances light gathering capacity and reduces artifacts caused by varying illumination angles, providing more design flexibility for efficient pixel space utilization.
Implementation Method 1
An optical surface of the microlens is asymmetrically shaped... light passing through the microlenses at certain angles is not directed onto the photodiode
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An image sensor includes a plurality of photosensitive sites (100), a plurality of asymmetrical-shaped microlenses (130) positioned spanning the photosensitive sites(100); wherein incoming light is directed in a predetermined direction by an asymmetrical surface of the asymmetrical-shaped microlenses (120) onto the photosensitive sites (100) for capturing the light in a substantially uniform manner.