Masked Pixel Arrays for Optical Sensor Color Selectivity
Solution Overview
Problem
Traditional multi-chromatic optical sensors trade color selectivity for reduced sensitivity and increased noise, limiting image quality and the amount of information contained in an image.
Innovation Solution
An optical sensor with an array of pixels and a filter assembly, where a mask with apertures of varying dimensions is used to ensure each pixel has a consistent relative response, allowing for a single integration time setting and balanced output across the array, incorporating filters for SWIR, NIR, red, green, and blue photons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional multi-chromatic optical filters are used for different pixels, then color selectivity is improved, but sensitivity is reduced and noise increases
Solution Approach 1:
The optical sensor divides the pixel array into different regions, with first pixels equipped with color filters and second pixels without color filters. This segmentation allows simultaneous capture of both color information and high-sensitivity luminance information, resolving the contradiction between color selectivity and sensitivity by assigning different functional roles to different pixel segments.
Solution Approach 2:
Different pixels are assigned different functional characteristics: first pixels have color filtering capability for color selectivity, while second pixels have full spectral sensitivity for high sensitivity measurements. This local differentiation of quality allows each pixel type to optimize its specific function without compromising the other.
2Measurement precision
If traditional multi-chromatic optical filters are used for different pixels, then color selectivity is improved, but noise increases
Solution Approach 1:
The sensor array is segmented into first pixels with color filters and second pixels without color filters. The second pixels capture full-spectrum light with high efficiency, providing clean signal data with minimal noise, while the first pixels provide color information. This segmentation reduces overall noise by avoiding the noise-introducing color filters in pixels where only luminance information is needed.
3Measurement precision
If color filter arrays are used to create multi-chromatic images, then color information is improved, but spatial resolution is reduced
Solution Approach 1:
The pixel array is segmented into first pixels with color filters and second pixels without color filters. The second pixels provide high spatial resolution luminance information without the spatial sampling limitations of color filter arrays, while the first pixels provide color information. This segmentation resolves the spatial resolution penalty typically imposed by color filter arrays.
Solution Approach 2:
The sensor merges the functionality of color-filtered pixels and unfiltered pixels into a single integrated array. By combining both types of pixels in one sensor, it simultaneously achieves color information capture and high spatial resolution luminance capture, eliminating the need to choose between the two capabilities.
4Measurement precision
If multiple integration time settings are used for different pixels, then color balance is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by adjusting the aperture dimensions in the mask for different pixel types. First pixels have apertures sized to limit light input to match their lower sensitivity due to color filters, while second pixels have larger apertures to maximize light capture. This parameter adjustment achieves balanced output across all pixels with a single integration time setting, avoiding the complexity of multiple integration time controls.
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 configuration enhances image quality by maintaining high sensitivity and low noise while achieving improved color selectivity and spatial and temporal resolution, enabling the capture of detailed multi-chromatic images.
Implementation Method 1
an array of pixels configured to convert photons into electrons for forming an image
Implementation Method 2
A filter assembly is operatively associated with the array of pixels for passing predetermined bandwidths of photons to the array of pixels
Data Source
Figure 1
Figure 2
AI summary
An optical sensor (100; 200) includes an array of pixels (102; 202) configured to convert photons into electrons for forming an image or to measure spectral content without forming an image. A filter assembly (104) is operatively associated with the array of pixels for passing predetermined bandwidths of photons to the array of pixels. A mask (108) is operatively associated with the array of pixels and the filter assembly. The mask includes a plurality of apertures (110, 112, 114, 116; 242, 244, 246, 248, 250) each for limiting photons passing through the filter assembly to a respective pixel (126, 128, 130, 132; 234, 235, 228, 229, 232, 233, 230, 231, 226, 227) in the array of pixels.