Tilted Narrow-Band Interference Filter for Gas Spectrometry
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Solution Overview
Problem
Current sensing technologies for detecting invisible, toxic gases in the atmosphere are expensive, unreliable, and lack the range to detect gases from a distance, making it challenging to locate and quantify these gases effectively.
Innovation Solution
A narrow-band optical interference filter system is used with a camera to detect target atmospheric gases by filtering incoming light based on absorption spectra, allowing for the detection of gases like methane, oxygen, and CO2, with a narrow filter bandwidth and tilt angle optimization to enhance spectral resolution and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If typical sensing equipment is used to detect atmospheric gases, then detection capability is provided, but the equipment is expensive, unreliable, and cannot detect gases from a distance
Solution Approach 1:
The patent changes the operating parameters of the interference filter, specifically tilting it at angles between 0-80 degrees relative to the optical axis, to shift the center wavelength and bandwidth of the filter. This allows the same filter to detect multiple different gases by adjusting the tilt angle, eliminating the need for multiple specialized sensors for different gases
Solution Approach 2:
The interference filter is designed to perform multiple detection functions by changing its tilt angle. A single filter can detect various gases including methane, carbon dioxide, and other atmospheric gases by adjusting the angle of incidence, making the system universal rather than requiring dedicated sensors for each gas type
2Measurement precision
If a narrow-band optical interference filter with tilt angle is used, then spectral resolution and detection range are improved, but the optical system complexity increases
Solution Approach 1:
The interference filter is mounted on a rotating mechanism that allows dynamic adjustment of the tilt angle during operation. This enables the system to scan through different wavelengths by changing the angle of incidence, providing spectral resolution comparable to more complex spectrometers while using a simpler filter-based approach
Solution Approach 2:
The interference filter acts as an intermediary element that converts angular information into spectral information. By tilting the filter at different angles, the system selectively transmits different wavelength bands, effectively using the filter as a wavelength-selective mediator between the broad-spectrum light source and the detector
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
The system enables efficient, remote detection and mapping of atmospheric gases with high spectral resolution, providing precise visualization and concentration analysis, even from a distance, using a compact and efficient design suitable for miniature payloads.
Implementation Method 1
A filter incidence narrow-band infrared spectrometer utilizes a narrow-band optical interference filter with a filter bandwidth and center wavelength that corresponds to a feature in an absorption spectrum of a target gas
Implementation Method 2
The center wavelength can be slightly greater than the target feature... transmission measurements collected over a range of incidence angles can be converted into a wavelength spectrum of the atmospheric absorption feature to confirm the presence of a target gas
Data Source
AI summary
A system and methods for optically detecting a target atmospheric gas are disclosed and described. An imaging system can include a narrow-band optical interference filter with a center wavelength that corresponds to a feature in an absorption spectrum of a target gas at a normal angle of incidence. An optical component can receive incoming light from the target gas that has passed through the narrow-band optical interference filter, wherein the narrow-band optical interference filter is tilted relative to the optical component, which tilt shifts the wavelength of light from each target point that is able to pass through the narrow-band optical interference filter. A camera can receive the incoming light that has been focused by the optical component. Multiple image frames are collected for different orientations of the system with respect to the target and analyzed to perform hyperspectral characterization of target gas absorption.