Image Sensor Sub-Pixel Polarizers for Glare Reduction
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Solution Overview
Problem
Current image sensors fail to capture polarization information of incoming light, which is crucial for studying polarizing minerals and applications like glare reduction in outdoor imaging.
Innovation Solution
A backside-illuminated image sensor with multiple photodiodes, each covered by conductive-line polarizers at different angles, and a single microlens per pixel, allowing for the detection and processing of polarization parameters through digital image processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional polarized filters are used to capture polarization information, then polarization sensitivity is improved, but quantum efficiency and light transmission are reduced
Solution Approach 1:
The patent replaces traditional mechanical polarized filters with conductive-line polarizers integrated directly over the photodiodes. This substitution eliminates the need for separate filter layers that block light, allowing the sensor to capture polarization information through the conductive lines themselves while maintaining high light transmission and quantum efficiency.
Solution Approach 2:
The conductive-line polarizers serve multiple functions simultaneously: they act as both the polarizing element for polarization detection and as part of the pixel structure itself. This multi-functionality allows the sensor to achieve polarization sensitivity without sacrificing quantum efficiency, as the same structure performs both polarizing and light-detecting roles.
2Measurement precision
If multiple photodiodes with polarizers at different angles are used per pixel, then polarization resolution is improved, but device complexity increases
Solution Approach 1:
The patent divides each pixel into multiple photodiodes, with each photodiode covered by a conductive-line polarizer at a specific angle (e.g., 0°, 45°, 90°, 135°). This segmentation allows the sensor to resolve polarization information by measuring light intensity at different angles simultaneously, achieving polarization resolution while keeping each individual photodiode structure simple.
Solution Approach 2:
The patent adds the polarization angle dimension to the traditional intensity-only measurement. By incorporating photodiodes with polarizers at different angular orientations within each pixel, the sensor transforms a single-intensity measurement into a multi-dimensional measurement that includes polarization angle information, thereby resolving polarization without excessive complexity.
3Device complexity
If a single microlens is used per pixel instead of separate microlenses for each photodiode, then device complexity is reduced, but light focusing precision may be compromised
Solution Approach 1:
The patent merges multiple microlenses into a single shared microlens for each pixel containing multiple photodiodes. This consolidation reduces the total number of microlenses required, simplifying the manufacturing process and reducing device complexity. The single microlens focuses incoming light onto the appropriate photodiodes within the pixel, maintaining sufficient focusing precision for polarization detection.
Solution Approach 2:
The single microlens serves multiple photodiodes simultaneously within a pixel, performing the focusing function for all of them. This universal approach allows one microlens to support multiple detection elements, reducing overall complexity while maintaining the necessary light-focusing capability for accurate polarization measurement across all photodiodes in the pixel.
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
Enables high quantum efficiency and full-color imaging while resolving polarization, reducing glare and enhancing image contrast by determining polarization angles and percentages, even without traditional polarized filters.
Implementation Method 1
Light is focused by the microlenses 202 through conductive metal polarizers 204 (corresponding to a polarizer 112, 114, 108, or 110) onto photodiode 206
Implementation Method 2
Each cell of photodiodes 106 has a vertical or zero-degree conductive-metal polarizer 108 over a photodiode, a horizontal or 90-degree conductive-metal polarizer 110 over a photodiode, a 45-degree conductive-metal polarizer 112 over a photodiode, and a 135-degree conductive-metal polarizer 114 over a photodiode
Implementation Method 3
camera 100 (FIG. 1) focuses light through a lens 102 onto a polarization-sensitive image sensor 104, image sensor 104 having multiple cells 106 of photodiodes
Data Source
AI summary
An image sensor configured to resolve intensity and polarization has multiple pixels each having a single microlens adapted to focus light on a central photodiode surrounded by at least a first, a second, a third, and a fourth peripheral photodiodes, where a first polarizer at a first angle is disposed upon the first peripheral photodiode, a third polarizer at a third angle is disposed upon the third peripheral photodiode, a second polarizer at a second angle is disposed upon the second peripheral photodiode, and a fourth polarizer at a fourth angle is disposed upon the fourth peripheral photodiode, the first, second, third, and fourth angles being different. In embodiments, 4 or 8 peripheral photodiodes are provided, and in an embodiment the polarizers are parts of an octagonal polarizer.