Open-Path Optical Sensors Using Mid-IR Lasers for Gas Mapping
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Solution Overview
Problem
Existing technologies are inadequate for accurately measuring greenhouse gases and air pollutants, such as nitrous oxide (N2O) and ammonia (NH3), in an open-path configuration with multi-pass cell and mid-IR coherent light source, particularly for agricultural and environmental monitoring.
Innovation Solution
A system utilizing open-path sensing equipment with mid-IR lasers, mirrors, and detectors mounted on UAVs or towers, capable of passive air sampling and providing fast response and low power consumption, achieving precise measurements of greenhouse gases and air pollutants with high sensitivity and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If open-path sensing equipment is mounted on UAVs or towers for environmental monitoring, then measurement precision and sensitivity for greenhouse gases and air pollutants are improved, but device complexity and power consumption increase
Solution Approach 1:
The sensing system is divided into separate functional modules: mid-IR laser source unit, optical path unit with mirrors, detector unit, and control electronics. Each module can be independently optimized and mounted separately on the UAV or tower structure, reducing overall system complexity while maintaining high measurement precision through modular integration
Solution Approach 2:
The patent introduces an optical intermediary system using mid-IR lasers and reflection mirrors to enable passive air sampling. This intermediary optical path allows the system to measure greenhouse gases and air pollutants without direct contact with the sample air, reducing contamination risks and simplifying the sampling process while maintaining high sensitivity
2Measurement precision
If open-path sensing equipment is mounted on UAVs or towers for environmental monitoring, then measurement precision and sensitivity for greenhouse gases and air pollutants are improved, but power consumption increases
Solution Approach 1:
The system employs periodic modulation of the mid-IR laser source and synchronized detection cycles. By operating in periodic intervals rather than continuous mode, the system achieves high measurement precision while significantly reducing average power consumption, enabling extended operation on UAVs with limited power capacity
Solution Approach 2:
The patent utilizes parameter changes in the mid-IR laser wavelength to match the absorption spectra of target gases. By tuning the laser wavelength to specific absorption features of greenhouse gases and air pollutants, the system achieves high sensitivity measurements with reduced power requirements compared to broadband detection methods
3Productivity
If fast response measurement is implemented at high frequency, then productivity and real-time monitoring capability are improved, but device complexity and power consumption increase
Solution Approach 1:
The optical sensing system operates continuously with the mid-IR laser continuously probing the air path. This continuous operation enables fast response measurements at high frequencies without requiring complex switching mechanisms or intermittent sampling, thereby improving productivity while keeping device complexity manageable through steady-state operation
4Measurement precision
If multi-pass cell configuration is used to increase path length, then measurement precision and sensitivity are improved, but device complexity and volume increase
Solution Approach 1:
Instead of increasing path length by extending the physical volume of the sensor, the patent uses optical reflection to fold the light path through the air volume multiple times. By directing the laser beam through a series of reflections in a compact three-dimensional arrangement, the system achieves long effective path length for high measurement precision while maintaining a small physical footprint suitable for UAV mounting
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
Enables accurate, real-time measurement of greenhouse gases and air pollutants with high sensitivity and precision, facilitating spatial mapping and emission source localization across various environments, including croplands, grasslands, and industrial facilities.
Implementation Method 1
at least one mid-infrared (mid-IR) laser disposed thereon and configured to provide light at a predetermined wavelength for a particular analyte
Implementation Method 2
a detector configured to receive signals of light reflected from the plurality of reflection mirrors
Implementation Method 3
a plurality of reflection (or focusing) mirrors configured to reflect light from each mid-IR laser
Implementation Method 4
The system can be configured to measure the at least one analyte with a precision resolving about 1 part in 1000 of the ambient level
Data Source
AI summary
Systems and methods are provided for measuring analytes in the air over an area. Open-path sensing equipment can be used to measure the concentration of one or more analytes over the area. The open-path sensing equipment can include at least one light source configured to provide light at a respective predetermined wavelength, a detector, and a plurality of mirrors. The open-path sensing equipment can further include and/or be operated with electronics, such as field programmable gate array (FPGA) electronics.