Tilted Interference Filter for Gas Detection Spectral Resolution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing technologies for detecting undesirable gases in the atmosphere are expensive, unreliable, and lack sufficient range to detect gases from a distance, making it challenging to locate and quantify these gases effectively.
Innovation Solution
A system utilizing a narrow-band optical interference filter with a specific filter bandwidth and center wavelength corresponding to absorption spectrum features of target gases, oriented at a tilt angle relative to an optical component, to optically detect target gases by analyzing the transmission measurements across a range of incidence angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If typical sensing equipment is used to detect gases, then detection capability is provided, but the equipment is expensive, unreliable, and cannot detect gases from a distance
Solution Approach 1:
The patent replaces complex mechanical sensing equipment with an optical detection system using interference filters and cameras. The system uses optical interference phenomena rather than mechanical sensors to detect gas concentrations, achieving reliable long-range detection while reducing device complexity and cost
Solution Approach 2:
The patent changes the detection parameter from electrical/mechanical sensing to optical wavelength filtering. By using narrow-band interference filters with specific center wavelengths matched to gas absorption features, the system achieves reliable detection through spectral analysis rather than complex sensor arrays
2Measurement precision
If a narrow-band optical interference filter is used with a bandwidth of 5 nm or less, then spectral resolution is improved to avoid confusion with multiple absorption features, but the filter bandwidth is reduced
Solution Approach 1:
The patent optimizes the filter bandwidth parameter to 5 nm or less, matching the absorption feature widths of target gases. This parameter optimization provides sufficient spectral resolution to distinguish between different gas absorption features while maintaining adequate signal transmission for reliable detection
Solution Approach 2:
The patent applies narrow-band filtering at specific wavelength regions corresponding to absorption features of interest. Rather than using a uniformly narrow filter across all wavelengths, the system selects filter center wavelengths and bandwidths optimized for specific gas detection applications, providing local spectral resolution where needed
3Reliability
If the interference filter is tilted at an angle to maximize signal strength, then detection sensitivity is improved, but the angle of incidence must be precisely controlled
Solution Approach 1:
The patent pre-tilts the interference filter at a specific angle (e.g., 45 degrees) relative to the optical component during assembly. This preliminary alignment action maximizes the optical path difference and interference effect, thereby maximizing signal strength without requiring precise real-time control during operation
Solution Approach 2:
The patent introduces asymmetric tilting of the interference filter relative to the optical component. Rather than maintaining symmetric normal incidence, the deliberate asymmetric angle creates constructive interference patterns that enhance the detection signal, trading manufacturing alignment complexity for improved detection reliability
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 detection and quantification of target gases by maximizing signal strength and reliability through sharp transitions in absorptivity and optimal filter alignment, overcoming the limitations of existing technologies.
Implementation Method 1
A filter incidence narrow-band infrared spectrometer includes a camera, a lens, and a narrow-band optical interference filter
Implementation Method 2
a center wavelength that corresponds to a feature in an absorption spectrum of a target gas
Implementation Method 3
The tilt angle for the filter with respect to the target line of sight defines a bandpass and maximum wavelength of light that is able to pass through the narrow-band optical interference filter. The incident angle of light on the interference filter changes across the image scene of the camera
Data Source
AI summary
A system and methods for optically detecting a target 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, where 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 charactetization of target gas absorption.