Laser Firing Synchronization for LA-ICP-MS Aliasing Control
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Solution Overview
Problem
In LA-ICP-MS systems, aliasing and drift caused by misalignment between the laser ablation firing cycle and the mass-spectrometer mass cycle lead to inaccurate signal intensity measurements, which can be mitigated but result in increased analysis time or material loss.
Innovation Solution
A system and method that optimize the alignment of the laser firing period with the mass measurements of the mass-spectrometer by using an input unit to receive timing signals, a processor to translate these signals into triggering signals for the laser, a delay unit to adjust the firing timing, and an output unit to modify the signals for compatibility with the laser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the laser fires at a fixed frequency determined by the response time of the sample chamber and transfer system, then the system can operate with conventional response times, but the analysis time becomes considerably longer
Solution Approach 1:
The patent applies dynamics by making the laser firing frequency variable rather than fixed. The control system dynamically adjusts the laser repetition rate to match the mass spectrometer's measurement cycle, allowing optimization between analysis speed and measurement accuracy. This resolves the contradiction by enabling faster analysis when the mass spectrometer can keep up with the laser, while maintaining accuracy when synchronization is achieved.
Solution Approach 2:
The patent changes the parameter of laser repetition rate from a fixed value determined by response time to a variable parameter that can be adjusted to match the mass spectrometer's measurement capabilities. This parameter change allows the system to operate at higher speeds when possible while maintaining synchronization for accurate measurements, thereby reducing analysis time without sacrificing precision.
2Productivity
If fast ablation cells with response times of 1-100 ms are used to reduce analysis time and improve signal intensity, then aliasing and drift occur causing inaccurate signal intensity measurements
Solution Approach 1:
The patent implements feedback by using the timing signals from the mass spectrometer to control the laser firing. The system continuously monitors the mass spectrometer's measurement cycle and adjusts the laser repetition rate accordingly. This feedback mechanism eliminates aliasing and drift by ensuring the laser always fires at rates that the mass spectrometer can accurately measure, thereby maintaining measurement precision while enabling the use of fast ablation cells for improved productivity.
Solution Approach 2:
The patent applies preliminary action by pre-synchronizing the laser firing with the mass spectrometer measurement cycle before analysis begins. The system establishes the correct repetition rate and timing relationship in advance, preventing aliasing and drift from occurring during the actual analysis. This preliminary synchronization allows fast ablation cells to be used effectively without compromising measurement accuracy.
3Measurement precision
If the laser repetition rate is increased to eliminate aliasing, then signal measurement accuracy improves, but excessive material is removed from the target sample
Solution Approach 1:
The patent applies partial action by using only the necessary laser repetition rate required to eliminate aliasing, rather than continuously operating at maximum speed. The control system adjusts the laser rate to match the mass spectrometer's capabilities, using the minimum rate needed for accurate measurement. This prevents excessive material removal while still eliminating aliasing, thereby maintaining measurement precision without unnecessary loss of target material.
4Measurement precision
If sequential measurement by the mass-spectrometer is used with long response times, then the true composition of the target material is represented, but the time to complete analysis is considerably increased
Solution Approach 1:
The patent applies periodic action by synchronizing the laser firing with the periodic measurement cycle of the mass spectrometer. Instead of using fixed, slow repetition rates, the system uses periodic laser pulses that are timed to match each measurement cycle. This allows sequential measurement to continue representing true composition accurately while reducing the overall number of cycles needed, thereby decreasing analysis completion time.
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 eliminates aliasing and reduces drift, resulting in more accurate and precise signal measurements without increasing analysis time or material loss, thereby improving the overall efficiency of LA-ICP-MS systems.
Implementation Method 1
a ablating a portion of the sample material with one or more laser pulses to generate a plume containing particles and/or vapour ejected or otherwise generated from the target
Implementation Method 2
an inductively-coupled-plasma apparatus for sample dissociation and ionization
Implementation Method 3
The carrier gas containing the target material is directed to the inductively-coupled-plasma where the aerosol is dissociated and ionized
Implementation Method 4
a mass-spectrometer apparatus for mass separation and signal measurement
Data Source
AI summary
The invention relates to a system for aligning the firing of a laser-ablation apparatus to a signal or property of an inductively-coupled-plasma mass-spectrometer apparatus. At least one kind of input unit that receives timing data from the mass-spectrometer and isolates the system. A processor configured to translate the mass cycle of the mass-spectrometer into a series of triggering signals to fire the laser. A delay circuit to retard the triggering signals by a specified duration. At least one kind of signal output unit to deliver a triggering signal to the laser. A method for configuring a system for controlling a laser in laser-ablation inductively-coupled-plasma mass-spectrometry as above. A computer program product for controlling a laser in laser-ablation inductively-coupled-plasma mass-spectrometry as above.