Handheld LIBS Spectrometer with Auto-Focusing and Localized Purging
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Solution Overview
Problem
Portable and handheld LIBS devices face challenges in accurately analyzing lower atomic number elements like beryllium, sodium, carbon, boron, oxygen, and nitrogen due to low signal levels and the need for precise laser focusing and sample cleanliness, while also requiring efficient use of argon gas for purging.
Innovation Solution
A handheld LIBS spectrometer system that uses an eye-safe laser with adjustable focusing capabilities to precisely focus on the sample, automatically cleans the sample surface, and conserves argon gas by using a small cartridge with localized and controlled gas flow, allowing for multiple measurements across the sample to account for non-homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high powered laser is used to produce plasma for LIBS analysis, then the ability to detect lower atomic number elements is improved, but eye safety deteriorates
Solution Approach 1:
The patent changes the wavelength parameter of the laser from conventional visible/near-IR ranges to the 1.5 micron region. This specific wavelength change enables eye safety (Class 1 or Class 2 rating) while maintaining sufficient power density for plasma generation and LIBS analysis of lower atomic number elements
2Power
If the laser is focused to a small spot size to achieve sufficient power density for plasma ignition, then the ability to generate plasma with lower power lasers is improved, but the precision of focusing required increases
Solution Approach 1:
The patent implements an automatic focusing system that uses feedback from the spectrometer to detect plasma generation and automatically adjusts the laser focus to the optimal position. This self-adjusting mechanism eliminates the need for manual focusing precision while ensuring consistent plasma generation
Solution Approach 2:
The system uses spectrometer feedback to detect plasma emission and automatically adjusts the focusing lens position to optimize plasma generation. This closed-loop control system maintains precise focusing without requiring manual intervention or high mechanical precision
3Measurement precision
If argon gas is used to purge the sample chamber to improve signal detection, then the detection of reactive elements like carbon, phosphorous, and sulfur is improved, but gas consumption increases
Solution Approach 1:
The patent implements localized purging where argon gas is directed specifically to the plasma generation region rather than the entire sample chamber. This targeted approach maintains the inert atmosphere needed for detecting reactive elements while minimizing overall gas consumption
Solution Approach 2:
The system uses periodic or pulsed purging rather than continuous flow, activating the argon gas supply only during laser pulses when plasma generation occurs. This intermittent purging maintains detection precision for reactive elements while significantly reducing gas consumption
4Measurement precision
If multiple measurements are taken across the sample to account for non-homogeneity, then the accuracy of elemental analysis is improved, but the time required for analysis increases
Solution Approach 1:
The system takes a limited number of measurements at strategically selected locations rather than exhaustive sampling. This partial action approach provides sufficient statistical representation of sample homogeneity while keeping analysis time acceptable for field applications
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 elemental analysis of lower atomic number elements with improved precision and reduced argon gas consumption, enhancing the portability and effectiveness of handheld LIBS devices by ensuring consistent results and efficient operation.
Implementation Method 1
a laser source generating a laser beam for creating a plasma at a location on a sample
Implementation Method 2
creating a plasma at a location on a sample
Implementation Method 3
a spectrometer responsive to photons emitted by the sample at said location
Implementation Method 4
an adjustable focusing lens focused to a small spot size on the sample
Implementation Method 5
Some elements such as carbon, phosphorous, and sulfur react with oxygen resulting in a very low level signal
Data Source
AI summary
A handheld LIBS spectrometer includes an optics stage movably mounted to a housing and including a laser focusing lens and a detection lens. One or more motors advance and retract the optics stage, move the optics stage left and right, and/or move the optics stage up and down. A laser source in the housing is oriented to direct a laser beam to the laser focusing lens. A spectrometer subsystem in the housing is configured to receive electromagnetic radiation from the detection lens and to provide an output. A controller subsystem is responsive to the output of the spectrometer subsystem and is configured to control the laser source and motors. In this way, auto-calibration, auto-clean, and auto-focus, and/or moving spot functionality is possible.