Sub-diffraction Light Receptors with Flexible Optical Filters
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Solution Overview
Problem
Conventional image sensor technologies face challenges in achieving optimal color accuracy and sensitivity due to limited color filters, which result in reduced resolution and photon loss, and struggle to dynamically optimize between resolution and color fidelity and sensitivity.
Innovation Solution
An array of sub-diffraction limit-sized light receptors with a flexible optical filter structure comprising multiple filter types, allowing for the creation of data elements from multiple bit elements, enabling the use of various filter combinations without degrading resolution, and allowing for high sensitivity and dynamic range optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional color filters are used in image sensors, then color imaging is achieved, but resolution is reduced and photon loss increases
Solution Approach 1:
The invention segments the color filtering function by using multiple discrete filter pixels (e.g., red, green, blue, cyan, yellow, magenta, white, black) arranged in a pattern where each filter pixel covers one or more photodetectors. This segmentation allows selective placement of different filter types without requiring every pixel to have a complete set of color filters, thereby maintaining resolution while achieving color imaging through computational combination of signals from different filter pixels.
Solution Approach 2:
The invention transitions from traditional in-pixel color filtering to a spatially distributed filter arrangement where color information is obtained by combining signals from multiple pixels with different filter types. This dimensional shift allows the system to treat color filtering as a spatial sampling problem rather than an in-pixel constraint, enabling higher resolution through sub-pixel filter patterns and computational reconstruction.
2Measurement precision
If conventional color filters are used in image sensors, then color imaging is achieved, but photon loss increases
Solution Approach 1:
The invention makes filter pixels universal by designing them to serve multiple functions: color filtering, sensitivity enhancement, and dynamic range optimization. Different filter pixels (including white, black, and colored filters) can be strategically placed to optimize both color accuracy and photon utilization. The system can adaptively use different filter pixels for different imaging conditions, reducing overall photon loss while maintaining color fidelity.
Solution Approach 2:
The invention changes the optical parameters of filter pixels by incorporating various filter types (colored, white, black, long-pass, short-pass) with different transmittance characteristics. This parameter diversity allows the system to optimize photon utilization by selecting appropriate filter pixels for different spectral regions and lighting conditions, reducing photon loss while maintaining color accuracy through computational processing.
3Measurement precision
If more color filters are used to improve color accuracy, then color fidelity improves, but device complexity increases
Solution Approach 1:
The invention segments the color filter array into discrete, independently configurable filter pixels that can be implemented using standard semiconductor fabrication processes. Each filter pixel can be a simple optical filter layer or structure, avoiding the need for complex multi-layer interference filters or liquid crystal structures in every pixel. This segmentation simplifies the actual filter structure while achieving high color fidelity through the combination of multiple filter pixel types.
Solution Approach 2:
The invention uses computational copying and reconstruction algorithms to generate full-color information from a sparse array of filter pixels. Instead of requiring every pixel to have complete color filter sets, the system captures signals from strategically placed filter pixels and computationally reconstructs the full color image, reducing physical filter complexity while maintaining color fidelity through digital processing.
4Manufacturing precision
If sub-diffraction limit pixels are used to increase resolution, then spatial resolution improves, but sensitivity to single photoelectrons becomes more challenging
Solution Approach 1:
The invention merges signals from multiple sub-diffraction limit pixels that share the same or complementary filter characteristics to improve photoelectron detection sensitivity. By combining signals from adjacent pixels with identical or related filter types, the system maintains single-photon sensitivity while preserving the high spatial resolution provided by the sub-diffraction limit pixel size. This merging occurs in the signal processing stage without compromising the physical resolution benefits.
Solution Approach 2:
The invention compensates for reduced sensitivity in individual sub-diffraction limit pixels by introducing a temporal and spatial integration dimension. Signals from multiple sub-diffraction pixels are integrated over time and space through the filter pixel pattern and readout architecture, allowing the system to maintain both high spatial resolution and adequate sensitivity by distributing the detection function across multiple pixels rather than relying on a single pixel's sensitivity.
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 approach enhances sensitivity and color accuracy, enables spectral imaging, reduces color artifacts, and allows for dynamic optimization between resolution and color fidelity and sensitivity, while minimizing photon loss and vignetting.
Implementation Method 1
an optical filter structure disposed over the light receiving surface, the optical filter structure being comprised of an array of filter pixels each having an associated passband spectral characteristic
Implementation Method 2
Each light receptor may be configured to output a binary valued bit element and to change state between an off-state and an on-state by the absorption of at least one photon
Data Source
Figure 1~3
Figure 2~4A
Figure 4B
AI summary
An apparatus includes an array of sub-diffraction limit-sized light receptors formed in a substrate having a light receiving surface. Each light receptor may be configured to output a binary valued bit element and to change state between an off-state and an on-state by the absorption of at least one photon. The apparatus further includes an optical filter structure disposed over the light receiving surface, the optical filter structure having of an array of filter pixels each having an associated passband spectral characteristic. A data element obtained from the array of sub-diffraction limit-sized light receptors is composed of a plurality of the bit elements output from a plurality of light receptors that underlie filter pixels having at least two different passband spectral characteristics.