Time of Flight Mass Spectrometer Timing Synchronization
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Solution Overview
Problem
Time of Flight mass spectrometers face timing uncertainty and systematic errors due to asynchronicity between the sampling clock and the ion flight acquisition system, leading to broadening of detected signals and reduced system resolution, even when integrating multiple ion flights.
Innovation Solution
Digitizing both the accelerating pulse and ion arrival signals using a single or synchronized Analogue to Digital Converter (ADC) with a shared sampling clock, allowing precise determination of ion acceleration and arrival times, and calculating the mass-to-charge ratio based on their difference, thereby reducing timing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the accelerating pulse is initiated from the sampling clock, then the timing synchronization is improved, but jitter is introduced in the accelerating event which is equivalent to timing uncertainty
Solution Approach 1:
The patent introduces a time stamping mechanism as an intermediary between the sampling clock and the accelerating pulse generation. The ADC captures the accelerating pulse and assigns a precise time stamp based on the sampling clock, but the actual pulse timing is determined by the captured signal rather than directly by the clock, thus eliminating jitter while maintaining synchronization precision
Solution Approach 2:
The patent performs preliminary digitization of the accelerating pulse by the ADC before ion injection. The time stamp is assigned based on this preliminary capture, allowing the system to record the exact timing of the accelerating event without the subsequent ion flight being affected by clock jitter
2Measurement precision
If many flights are integrated, then the timing error decreases with the square root of the number of flights, but the uncertainty results in broadening of the integrated detected signal and an apparent reduction in the system resolution
Solution Approach 1:
The patent uses the captured accelerating pulse signal as feedback to determine the precise injection time. By continuously monitoring the accelerating pulse and using its captured position to calculate flight time, the system maintains consistent and accurate timing references for each flight, preventing signal broadening during integration
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 enhances the precision of ion flight time measurement, improving the mass spectrometer's resolution and accuracy by eliminating systematic timing errors and jitter, resulting in sharper detected signals and more precise mass determination.
Implementation Method 1
applying an accelerating pulse to an acceleration electrode in order to accelerate ions into a field free or drift region of a mass analyser
Implementation Method 2
detecting at least some of the ions after the ions have passed through the field free or drift region using an ion detector
Data Source
AI summary
A Time of Flight Acquisition system is disclosed wherein a digitiser (6) is used to digitise an acceleration pulse (2) which is applied to an acceleration electrode of a Time of Flight mass analyzer. The digitiser (6) is then switched to digitise an ion arrival signal which is output from an ion detector (5).