Mobile Laser Analyte Detection with Reference Cross-Correlation
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Solution Overview
Problem
Current remote detection methods for gases in fluid media, such as air, face challenges in sensitivity and specificity, particularly in polluted environments, where they struggle to distinguish the target analyte from other substances, leading to inaccurate readings and false indications.
Innovation Solution
The use of a tunable diode laser system with a reference substance having identical spectral properties to the analyte, combined with a mobile or stationary detection unit, which employs a broad band light source and a semiconductor laser to scan wavelengths across the absorption feature profile of the analyte, allowing for precise detection and measurement through cross-correlation analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If remote detection methods are used for gases in fluid media, then detection capability is provided, but sensitivity and specificity are insufficient particularly in polluted environments
Solution Approach 1:
The detection method is segmented into multiple wavelength measurements across the absorption feature profile. By scanning through multiple wavelengths and performing cross-correlation analysis with reference spectra, the system isolates the specific analyte signal from background interference, thereby improving detection sensitivity and specificity in polluted environments.
Solution Approach 2:
The system changes the wavelength parameter across the absorption feature profile of the analyte. By measuring absorption at multiple wavelengths and comparing the spectral pattern to a reference, the method distinguishes the target analyte from other substances, resolving the contradiction between detection capability and interference resistance.
2Measurement precision
If laser wavelength is scanned across absorption feature profile, then detection accuracy is improved, but measurement time increases
Solution Approach 1:
Reference absorption spectra are pre-measured and stored for the analyte and background substances. During actual detection, the system quickly scans the wavelength range and performs cross-correlation with the pre-stored reference spectra, avoiding the need to scan and analyze the entire spectrum in real-time, thus reducing measurement time while maintaining accuracy.
Solution Approach 2:
The system uses reference copies of absorption spectra stored in memory. By comparing the measured spectrum against these pre-stored reference copies through cross-correlation analysis, the system rapidly identifies the analyte without requiring exhaustive spectral scanning, thereby reducing measurement time while preserving detection accuracy.
3Measurement precision
If cross-correlation analysis is used with reference substance, then selectivity is improved, but system complexity increases
Solution Approach 1:
A reference substance with identical spectral properties to the analyte serves as an intermediary. The reference substance provides a known absorption spectrum that acts as a template for cross-correlation analysis. This intermediary enables selective analyte detection by providing a reference pattern for comparison, improving selectivity without requiring complex identification algorithms.
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 high-sensitive, real-time detection of analytes with high selectivity, reducing interference from other substances and providing accurate concentration measurements, even in complex environments like those around chemical plants.
Implementation Method 1
Wavelength of light beam coincides with specific feature in absorption spectrum of analyte under detection
Implementation Method 2
Absorption of the gas is detected by detecting an unbalance in side bands signals caused by the frequency modulation
Implementation Method 3
Light beam emitted by apparatus is scattered and/or reflected by target
Implementation Method 4
Light beam emitted by apparatus is scattered and/or reflected by target
Data Source
AI summary
Apparatus for remote laser-based detection of a analyte in a remote target region; comprising a reference container for housing a reference substance identical with the analyte; a laser unit which constituted to emit a laser beam of a tuneable wavelength towards the target region to be analysed and along a reference path which passes through the reference container for detecting the reference substance; a laser control means constituted to control wavelength of the laser beam during detection periods such that the laser wavelength is changed to allow detection of an optical absorption profile of the analyte during detection periods; an analytical detection unit which detects light from the target region and generates analytical signals during the detection periods, a reference detection unit which detects laser light passed through the reference container and generates reference signals during the detection periods; and an analysing means constituted to analyse the similarity of the analytical and reference signals or of one or more calculated functions respectively calculated from the analytical and reference signals for determining the concentration of the analyte in the target region.