Diffraction Pixel Layout for Filterless Color and Polarization Sensing
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Solution Overview
Problem
Conventional color image sensors suffer from lower sensitivity, signal-to-noise ratio, color crosstalk, and spatial resolution issues due to the use of absorptive color filters and non-complementary metal-oxide semiconductor (CMOS) materials, which also degrade quickly, and existing polarization-sensitive sensors experience light loss and low quantum efficiency.
Innovation Solution
An image sensor with a diffraction layer comprising electrically conductive or semi-conductive diffraction elements that scatter incident light onto sub-pixels, allowing for the determination of light state characteristics like color, polarization, and phase without the need for color filters or micro lenses, using a thin diffraction layer to create high-coherence interference patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absorptive color filters are used in conventional color image sensors, then color detection capability is improved, but sensitivity and signal-to-noise ratio deteriorate
Solution Approach 1:
The patent replaces absorptive color filters with a diffraction-based optical system. Instead of using material absorption to separate colors, the invention uses diffraction gratings to spatially separate wavelengths through interference patterns, substituting a mechanical/optical field-based approach for material-based filtering. This eliminates the inherent light loss in absorptive filters while maintaining color detection capability.
Solution Approach 2:
The patent changes the operational parameter from absorption to diffraction. By using diffraction gratings that manipulate light through interference rather than absorption, the system maintains wavelength discrimination capability while significantly improving light throughput and sensitivity. The diffraction pattern encodes spectral information that can be read by the sensor array.
2Measurement precision
If absorptive color filters are used, then color detection is enabled, but spatial resolution deteriorates due to color filter patterning
Solution Approach 1:
The patent transitions from a planar color filter array to a three-dimensional diffraction pattern encoding scheme. Instead of filtering colors in the spatial domain through patterned filters, the invention encodes spectral information in the angular and spatial frequency domains through diffraction, effectively adding dimensional complexity to the optical processing.
3Measurement precision
If non-CMOS materials are used for filters and micro lenses, then color and polarization sensitivity are improved, but fabrication complexity and cost increase
Solution Approach 1:
The patent creates a universal diffraction grating structure that can simultaneously encode both spectral and polarization information. Instead of requiring separate filter layers and micro-lenses for different functions, the single diffraction grating structure performs multiple optical functions, reducing fabrication complexity while maintaining sensitivity.
4Measurement precision
If non-focusing diffractive gratings are used in polarization-sensitive sensors, then polarization detection is enabled, but light loss increases and quantum efficiency deteriorates
Solution Approach 1:
The patent replaces non-focusing diffractive gratings with a focusing diffraction grating system. The focusing geometry concentrates diffracted light onto the sensor plane rather than allowing it to diverge, thereby maximizing light utilization and quantum efficiency while maintaining polarization detection capability through the diffraction-based encoding.
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 solution provides high sensitivity, spatial resolution, and color resolution, enabling the detection of various polarization states and phase information across a wide spectral range, while being manufacturable using conventional CMOS processes and maintaining long-term reliability.
Implementation Method 1
The diffraction layer includes a set of electrically conductive or semi-conductive diffraction elements or features for each pixel in the plurality of pixels. The diffraction features scatter incident light onto the sub-pixels.
Implementation Method 2
The provided interferometric imaging enables information about the light field (light state) incident at the pixels to be determined.
Data Source
AI summary
Light state image sensors and systems are provided. The light state image sensor includes a plurality of pixels, each of which includes a plurality of sub-pixels. A diffraction layer is disposed adjacent a light incident surface side of the array includes a set of electrically conductive or semiconductive diffraction features for each pixel. Each set of diffraction features includes linear elements disposed along different radii extending from a centerline of the respective pixel. Non-linear scattering elements can also be included in each set of diffraction features. Light state information, such as color and polarization state, of light incident on a pixel is determined by comparing ratios of signals between pairs of sub-pixels to values stored in a calibration table.