Spatially Resolved Gas Detection Camera for Satellite SNR
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Solution Overview
Problem
Current gas detection systems in satellite applications face challenges in achieving smaller ground pixels while maintaining good Signal to Noise Ratio (SNR), as they rely on spectrometers which disperse intensity over many spectral detector pixels, leading to low signal levels per pixel.
Innovation Solution
The system employs a camera instead of a spectrometer, utilizing a modified Michelson or Mach-Zehnder interferometer with a splitter and relay optics to provide instantaneous wide image spatially resolved detection of gas substances, allowing for smaller ground pixels and improved SNR through the use of broad and narrow band filters and optical path differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a spectrometer is used to disperse light over multiple spectral detector pixels, then spectral resolution is improved, but signal level per detector pixel deteriorates
Solution Approach 1:
The detection area is segmented into multiple detector pixels arranged in a 2D array, where each pixel captures light from a specific spatial location and spectral band combination. The beam splitter divides the incoming light into multiple beams that are directed to different detector pixels, enabling simultaneous spectral and spatial resolution without dispersing a single beam across many pixels sequentially.
2Measurement precision
If the ground pixel size is decreased, then spatial resolution is improved, but Signal to Noise Ratio deteriorates
Solution Approach 1:
The system performs continuous spectral scanning by rapidly switching between different spectral bands using the beam splitter and detector array, effectively capturing complete spectral information for each ground pixel within the integration time. This continuous measurement approach maintains high SNR even for small ground pixels by maximizing the use of available integration time.
3Measurement precision
If larger entrance apertures and smaller f-numbers are used, then ground pixel size can be reduced, but instrument size, weight, and cost increase
Solution Approach 1:
The system transitions from a 1D spectral dispersion approach to a 2D detection architecture where detector pixels are arranged in both spatial and spectral dimensions. This dimensional change allows simultaneous capture of spatial and spectral information without requiring large aperture optics, as the spectral information is encoded in the detector pixel arrangement rather than through physical dispersion over long optical paths.
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 enables smaller ground pixels with maintained SNR, reducing the size and cost of the instruments while providing effective gas detection, with the ability to achieve high SNR even in Low Earth Orbits.
Implementation Method 1
a beam splitter arranged to divide said broad band beam into a number of beams each having a different wavelength
Implementation Method 2
a detector comprising a number of detector pixels arranged in a two dimensional array... each detector pixel being arranged to detect an intensity of a beam of light at a particular wavelength
Implementation Method 3
utilizing a modified Michelson or Mach-Zehnder interferometer with a splitter and relay optics to provide instantaneous wide image spatially resolved detection
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The invention pertains to a method of spatially resolved detection of a gas substance in an area, comprising: imaging the area on a first image sensor, in a wavelength spectrum including an absorption wavelength peak corresponding to said gas substance; imaging the area on a second image sensor, to provide for each pixel of the first image a corresponding pixel of the second image for respective on- and off-peak wavelengths relative to the absorption wavelength; and providing a difference image as a function of the two pixel values of first and second image sensors to produce an image of the spatially resolved absorption wavelength corresponding to said gas substance.