Movable Coded Filter Gas Detection
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Solution Overview
Problem
Existing techniques for detecting gas concentrations, such as TDLS, NDIR, Polychromatry, and FTIR, face limitations in accurately identifying and quantifying atmospheric gases due to spectral signature overlaps with common atmospheric components like H2O and CO2, making it difficult to detect chemical contaminants from a distance.
Innovation Solution
A device utilizing a movable coded filter with slits that spectrally separates light and oscillates to cancel AC signals from non-interest gases, allowing only the AC signal from the gas of interest to be detected by a photo detector, which is then converted to a digital signal to determine the gas concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing gas detection techniques (TDLS, NDIR, Polychromatry, FTIR) are used to detect atmospheric gases, then gas concentration can be measured, but the ability to accurately identify and quantify gases is limited due to spectral signature overlaps with common atmospheric components like H2O and CO2
Solution Approach 1:
The patent employs a dynamically oscillating coded filter that changes its transmission characteristics over time. The filter oscillates between different positions to create time-varying transmission patterns that allow discrimination between gases with overlapping spectral signatures. This dynamic approach enables the system to resolve spectral interference from atmospheric components like H2O and CO2 while maintaining accurate detection of target gases.
Solution Approach 2:
The coded filter operates by periodically oscillating between different transmission states, creating a time-modulated signal. This periodic action allows the system to encode spectral information in the time domain, enabling differentiation between gases based on their distinct temporal transmission patterns even when their spectral signatures overlap in the frequency domain.
2Measurement precision
If a movable coded filter with multiple lanes and slits is used to cancel AC signals from non-interest gases, then specific gas detection is enhanced, but the device complexity increases
Solution Approach 1:
The coded filter is divided into multiple lanes, each containing multiple slits positioned at different locations. This segmentation allows each lane to be independently configured to cancel AC signals from specific non-interest gases while preserving signals from the gas of interest. The modular segmented structure enables tailored response for different gas species without requiring a completely complex system.
Solution Approach 2:
The oscillating coded filter acts as an intermediary element between the incoming light and the photo detector. By strategically positioning slits in different lanes, the filter mediates the interaction between light from multiple gas sources and the detector, selectively transmitting certain spectral components while blocking others through its time-varying transmission pattern.
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 method effectively enhances the detection of specific gases by canceling out interfering signals, providing a clear AC signal proportional to the gas concentration, thus overcoming the limitations of existing technologies in distinguishing between atmospheric gases and contaminants.
Implementation Method 1
An optical element is positioned to receive gas filtered light and spectrally separate the gas filtered light
Implementation Method 2
A movable coded filter with slits that spectrally separates light and oscillates to cancel AC signals from non-interest gases
Implementation Method 3
A photo detector is positioned to receive the spectrally separated light through slits in the moveable coded filter to provide an AC signal representative of a selected gas
Data Source
AI summary
A device for detecting gas concentrations includes a movable coded filter. An optical element is positioned to receive gas filtered light and spectrally separate the gas filtered light. A photo detector is positioned to receive the spectrally separated light through slits in the moveable coded filter to provide an AC signal representative of a selected gas.