Online Underwater LIBS Detection With Pressure-Balanced Gas Flow
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Solution Overview
Problem
Underwater Laser Induced Breakdown Spectroscopy (LIBS) detection is hindered by water absorption and scattering effects, quenching effects, and high water pressure, which affect optical signal excitation and collection efficiency, making it difficult to achieve accurate and stable detection in deep water environments.
Innovation Solution
An online detection device with a sealing pressure chamber and airflow control system that maintains a stable gaseous detection path using a balance gas storage tank and flow model to control airflow, ensuring plasma excitation and collection efficiency under high water pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser energy is reduced to prevent water breakdown and improve convergence accuracy, then plasma excitation efficiency is improved, but spectral signals are weakened
Solution Approach 1:
The patent introduces a gas medium (air or inert gas) as an intermediary between the laser and the underwater target. The gas forms a detection optical path that mediates the interaction between laser light and the target, enabling plasma excitation without direct water breakdown. This intermediary gas environment allows for controlled plasma formation while maintaining spectral signal quality.
2Productivity
If air blowing and water drainage are used to change the optical path from water environment to gas environment, then plasma excitation and collection efficiency are improved, but it becomes difficult to provide enough high pressure gas under high water pressure conditions
Solution Approach 1:
The patent employs a nested structure where a gas-filled chamber or gas flow system is integrated within the underwater detection device. The gas environment is nested within the high-pressure water environment, creating a protected detection zone. This nested configuration allows the gas-based plasma excitation system to operate effectively while being shielded from the external high-pressure water conditions.
Solution Approach 2:
The gas medium serves as an intermediary that creates a separate detection environment isolated from the high-pressure water. This intermediary gas layer or gas-filled chamber enables plasma excitation without requiring the entire system to withstand and manage high-pressure gas supply, thereby simplifying the overall gas supply requirements.
3Measurement precision
If conventional focusing methods are used underwater, then detection precision is maintained, but the system becomes complicated and difficult to operate under high pressure
Solution Approach 1:
The gas medium acts as an intermediary optical environment that simplifies the focusing process. Since the gas-filled detection path is isolated from the high-pressure water environment, conventional optical focusing methods can be applied without the complications of water pressure effects on optical components. The gas environment provides a stable, pressure-independent medium for light propagation and focusing.
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 device provides high sensitivity and easy operation for in-situ detection of underwater elements by forming a stable gas environment, improving plasma excitation and collection efficiency without complex focusing processes.
Implementation Method 1
A Laser Induced Breakdown Spectroscopy (LIBS) technology uses laser light for exciting a target substance to form plasma. When excited atoms, ions or molecules in the plasma are transitioned to a low energy level or a ground state, photons of specific energy are emitted outward to form characteristic spectra.
Implementation Method 2
the absorption and scattering effects for light by water, a quenching effect of water
Implementation Method 3
the absorption and scattering effects for light by water
Implementation Method 4
a balance gas storage tank produces gas with the same pressure as underwater, and a flow model is invoked according to the current water pressure to accurately control the flow rate of airflow
Implementation Method 5
a flow model is invoked according to the current water pressure to accurately control the flow rate of airflow under a water environment, so that a stable gas environment is formed in a gas probe
Data Source
AI summary
An online detection device underwater elements includes an LIBS system in a sealing pressure chamber and an external airflow control system. The airflow control system has a gas probe bin and a gas source. An opening is formed at one end of the gas probe bin while the other end and the sealing pressure chamber are hermetically partitioned through a glass window. A laser in the LIES system outputs laser to an underwater object surface to be detected for generating plasma spectra. A spectrometer collects plasma spectra returned along an original optical path. When the device operates in water, the balance gas storage tank produces gas with the same pressure as underwater. A flow model is invoked according to the current water pressure to accurately control the air flow rate to form a stable gas environment in the gas probe, which improves the plasma excitation and collection efficiency.