Handheld LIBS Spectrometer Argon Gas Conservation
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Solution Overview
Problem
Portable and handheld LIBS devices face challenges in accurately analyzing samples with lower atomic number elements like beryllium, sodium, carbon, boron, oxygen, and nitrogen due to low signal detection and require precise laser focusing and sample cleaning, especially for non-homogeneous samples, while also needing to conserve argon gas for purging.
Innovation Solution
A handheld LIBS spectrometer system that uses an eye-safe laser with automatic focusing and cleaning capabilities, conserving argon gas by using a small cartridge and directing it only to the sample location, and moving the laser beam to multiple spots on the sample for accurate analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high flow rate argon gas is used to purge the sample chamber, then the detection accuracy for lower atomic number elements is improved, but the argon gas consumption increases significantly
Solution Approach 1:
The patent applies local quality by directing argon gas flow specifically to the sample location rather than purging the entire sample chamber. The gas flow is concentrated at the plasma generation point where it is most needed, creating a localized inert atmosphere that protects the plasma from atmospheric interference while minimizing overall gas consumption.
Solution Approach 2:
The patent segments the purging function into two parts: a small source of argon gas (cartridge or cylinder) and a delivery mechanism (tubing and nozzle) that transports the gas directly to the sample. This segmentation allows precise control of gas flow to only where needed, rather than filling the entire chamber with argon.
2Measurement precision
If the laser beam is focused to a small spot size for precise analysis, then the measurement precision is improved, but the device complexity increases due to focusing control requirements
Solution Approach 1:
The patent implements self-service through automatic focusing and automatic cleaning cycles. The system uses a movable optics stage that can be programmatically controlled to automatically adjust the laser focus and perform sample cleaning without operator intervention, eliminating the need for manual focusing adjustments while maintaining precise spot size control.
Solution Approach 2:
The patent replaces manual mechanical focusing adjustments with an automated optics stage system. The movable optics stage uses motorized or programmable mechanical positioning to control laser focus and sample cleaning, substituting operator skill-based manual adjustment with automated systematic control.
3Weight of moving object
If the laser power is reduced for portability, then the device weight and size are reduced, but the ability to generate sufficient plasma for detection is compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the laser wavelength to 1.5 micrometers, which is absorbed strongly by water in biological and organic samples. This wavelength selection allows efficient energy transfer and plasma generation with lower overall power requirements compared to traditional wavelengths, enabling portable device design while maintaining reliable plasma generation.
Solution Approach 2:
The patent uses periodic pulsed laser operation instead of continuous wave laser. The pulsed delivery concentrates energy in short bursts to generate plasma reliably, while allowing the laser and cooling systems to be smaller and more portable than continuous wave systems would require.
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 precise and efficient analysis of samples with improved accuracy and reduced argon gas consumption, making the device more portable and commercially viable by ensuring consistent results and minimizing operator intervention.
Implementation Method 1
a high powered laser that sufficiently heats a portion of the sample to produce a plasma
Implementation Method 2
As the plasma cools, eventually the electrons return to their ground states. In the process, photons are emitted at wavelengths unique to the specific elements comprising the sample
Implementation Method 3
Some elements such as carbon, phosphorous, and sulfur react with oxygen resulting in a very low level signal which can be difficult to detect and/or properly analyze. It is known to use an inert gas such as argon to purge the sample
Data Source
AI summary
A handheld LIBS spectrometer system features an optics stage moveable with respect to a housing and including a laser focusing lens. A laser source is mounted in the housing for directing a laser beam to a sample via the laser focusing lens. A detection fiber is mounted in the housing and is fixed relative thereto. A first mirror is fixed relative to the housing and includes an aperture for the laser beam. This mirror is oriented to re-direct plasma radiation for delivery to the detection fiber. A controller subsystem is responsive to the output of a spectrometer subsystem and is configured to control the laser source and the optics stage.