Multi-spectral methods and systems for day and night sensing of greenhouse gas sources from space
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Solution Overview
Problem
Current spectrometer-based systems for remotely sensing greenhouse gas sources from space are complex, limited to daytime operation, and have poor throughput, requiring large telescopes and complex scanning mechanisms, which restricts their ability to collect data efficiently and precisely locate sources, especially at night.
Innovation Solution
A multi-spectral imaging system using broad optical filters for both absorptive and emissive bands, combined with a cryocooler for simultaneous SWIR and MWIR operation, and Time Domain Integration techniques to improve signal-to-noise ratio, allowing for day and night sensing without the need for complex spectrometer-based systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spectrometer-based systems are used for remote sensing of greenhouse gases, then measurement precision is improved, but device complexity increases and productivity decreases
Solution Approach 1:
The system divides the spectral detection task into multiple discrete wavelength channels using filter arrays, where each filter targets specific absorption bands of different greenhouse gases. This segmentation allows parallel detection of multiple gas types simultaneously, maintaining measurement precision while avoiding the complexity of full spectrometers.
Solution Approach 2:
Optical filters serve as intermediaries between the incoming radiation and the detector, selectively transmitting only the wavelength bands corresponding to greenhouse gas absorption features. This intermediary approach simplifies the detection system by pre-processing the spectral information optically before detection, eliminating the need for complex mechanical spectrometers.
2Measurement precision
If spectrometer-based systems operate in MWIR band, then sensitivity is improved, but device complexity increases due to cryogenic cooling requirements
Solution Approach 1:
The system uses uncooled or passively cooled microbolometer detectors instead of expensive cryogenic detectors. While individual detector performance may be slightly lower, the overall system achieves sufficient sensitivity for greenhouse gas detection without the high cost and complexity of cryogenic cooling systems, making the solution more practical for widespread deployment.
3Device complexity
If SWIR band is used for measurement, then device complexity is reduced, but productivity decreases due to daytime operation limitation
Solution Approach 1:
The system is designed to operate in multiple spectral bands (both SWIR and MWIR) using the same basic detector architecture and filter array configuration. This multi-functionality allows the instrument to collect data during both daytime (using SWIR reflective signals) and nighttime (using MWIR thermal emission), effectively doubling the productive collection time while maintaining a relatively simple uncooled detector design.
4Measurement precision
If large telescope apertures are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
Instead of improving signal-to-noise ratio by increasing telescope aperture (spatial dimension), the system enhances detection capability by utilizing the spectral dimension - specifically targeting the strong absorption bands of greenhouse gases in the SWIR and MWIR regions. This dimensional shift allows smaller telescopes to achieve comparable or superior detection sensitivity by exploiting the inherent spectral contrast of greenhouse gas emissions and absorption features.
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 simplifies the system architecture, enables efficient day and night data collection, improves sensitivity, and reduces costs by allowing smaller telescopes and cryocooler integration, while maintaining high performance in detecting and quantifying greenhouse gas emissions.
Implementation Method 1
cooling both the instrument and the focal plane array to cryogenic temperatures using cryocoolers to minimize noise
Implementation Method 2
A first optical spectral filter is provided having a first optical bandpass that selects imaged, incoming radiance to be measured by preselected rows of the sensor array
Implementation Method 3
A sensor array, also referred to herein as a focal plane array or detector array, sensitive to wavelengths extending from about 1 micrometer to about 5 micrometers
Implementation Method 4
Time Domain Integration techniques to improve signal-to-noise ratio
Data Source
AI summary
Multi-spectral methods and systems for the day and night remote sensing (detection, identification, and quantification) of greenhouse gas emission sources from space are provided. The sensor system includes a telescope assembly that passively collects light from an observation area and directs that light through spectral, optical filters and to a sensor array having a plurality of rows and columns of pixels. Different groups of sensor array pixel rows are aligned to receive light that has passed through different optical filters. The filters have passbands corresponding to the reflective and emissive bands of gases of interest, as well as associated reflective and emissive reference bands, and broadband spectral bands. A set of image data frames is obtained as the field of view of the sensor system moves over an observation area and an aggregate image showing locations of detected gas emissions is generated using the collected data.