Sub-diffraction Color Filters for Sensor Spectral Accuracy
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Solution Overview
Problem
Conventional image sensor technologies face challenges in achieving optimal color accuracy and sensitivity due to the limited number of color filters used, which can reduce resolution and increase optical losses, leading to suboptimal performance in color imaging.
Innovation Solution
The use of an array of sub-diffraction limit receptors in combination with a color filter array that allows for a large number of different filter types to be used, enabling dynamic optimization between resolution and color fidelity and sensitivity by creating data elements from multiple bit elements, allowing for the use of various filter combinations without degrading resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional color filter arrays with limited filter types are used, then device complexity is reduced, but color accuracy and sensitivity deteriorate
Solution Approach 1:
The filter array is segmented into multiple types of filter pixels (first type, second type, third type, etc.) with different spectral characteristics. Each filter pixel type is associated with multiple underlying light receptors, allowing the system to capture spectral information across different wavelengths simultaneously, thereby improving color accuracy without requiring a single complex filter
Solution Approach 2:
The patent introduces a spectral dimension by using multiple filter pixel types with different passband characteristics (first passband, second passband, third passband) rather than relying solely on spatial resolution. This dimensional expansion allows the system to achieve superior color accuracy by measuring light properties across multiple spectral bands
2Measurement precision
If more color filters are used to improve color accuracy, then sensitivity is improved, but resolution deteriorates
Solution Approach 1:
Each filter pixel type is associated with multiple underlying light receptors (e.g., first filter pixel type associated with first, second, third light receptors). This segmentation allows the system to maintain high spatial resolution while incorporating multiple spectral measurement channels, as each spectral measurement is distributed across multiple receptor locations
Solution Approach 2:
The filter pixels serve multiple functions: they provide spectral filtering for color accuracy while their distributed association with multiple light receptors maintains spatial resolution. The system achieves both spectral discrimination and spatial detail by having filter pixels that can be associated with multiple underlying receptors
3Measurement precision
If conventional filter arrays are used, then optical losses are minimized, but color fidelity and sensitivity deteriorate
Solution Approach 1:
The patent employs filter pixels with different passband spectral characteristics (first passband, second passband, third passband) to optimize the transmission of different wavelength ranges. By matching filter passbands to the spectral sensitivity of underlying light receptors, the system maximizes optical efficiency and minimizes losses while achieving superior color fidelity
Solution Approach 2:
Different filter pixel types are strategically placed and associated with specific light receptors based on their spectral characteristics. Each filter-receptor pairing is optimized for its local spectral requirements, allowing the system to minimize optical losses at each measurement point while maintaining overall color fidelity across the entire array
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, improves color accuracy, enables spectral imaging, and reduces color artifacts, while providing additional freedom in selecting color filter materials and spectral properties, allowing for a single filter to cover multiple receptors and optimizing dynamic range.
Implementation Method 1
The array is illuminated through an optical filter structure comprised of a plurality of filter pixels, each having an associated passband spectral characteristic
Implementation Method 2
Each light receptor is 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 scalar valued multi-bit element and to change state based on 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 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 combination of a plurality of the multi-bit elements output from a plurality of light receptors that underlie filter pixels having at least two different passband spectral characteristics.