Laser Dither Clock Synchronization for Artifact-Free DLS
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Solution Overview
Problem
Existing methods to mitigate laser mode hopping in dynamic light scattering (DLS) applications are ineffective due to the difficulty in synchronizing laser dither frequencies with correlator frequencies, leading to measurement artifacts and errors, especially in high-frequency sampling scenarios.
Innovation Solution
Synchronize the laser dither frequency with the correlator's frequency to eliminate artifacts in the autocorrelation function, using a waveform generator to align the clocks and ensure identical periods in each sample, thereby stabilizing the laser intensity without introducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser dither frequency is increased to many times higher than acquisition frequency to avoid impacting measurement, then mode hopping mitigation is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent changes the dither frequency parameter to match the correlator sampling frequency exactly, rather than using a much higher frequency. This parameter adjustment allows mode hopping mitigation while avoiding the complexity of ultra-high frequency dithering systems.
Solution Approach 2:
The patent implements periodic dithering at the correlator's sampling frequency, creating a synchronized periodic action where the dither cycle aligns with the measurement integration period. This eliminates artifacts while maintaining simplicity.
2Device complexity
If laser dither frequency is set close to correlator frequency to reduce complexity, then device complexity is reduced, but frequency artifacts appear in measurements
Solution Approach 1:
The patent precisely adjusts the dither frequency parameter to exactly match the correlator sampling frequency, eliminating the frequency mismatch that causes artifacts. This precise parameter alignment resolves the contradiction between simplicity and measurement accuracy.
Solution Approach 2:
The system uses feedback synchronization where the dither frequency is locked to the correlator sampling frequency, ensuring they remain exactly matched during operation. This feedback mechanism prevents artifact generation while maintaining system simplicity.
3Device complexity
If different countable numbers of dither peaks are present in each integration period, then device complexity is reduced, but frequency artifacts appear because the dither is not synchronized
Solution Approach 1:
The patent establishes a synchronized periodic action where the dither frequency exactly matches the correlator sampling frequency, ensuring the same number of dither peaks appear in each integration period. This regular periodic alignment eliminates the random variations that generate artifacts.
Solution Approach 2:
The patent changes the dither frequency parameter to be exactly equal to the correlator sampling frequency, creating a rational relationship between the two frequencies. This parameter synchronization ensures consistent peak counting in each integration period, eliminating artifacts.
Data Source
AI summary
A method, system, and apparatus for synchronizing laser dither and correlator clocks to improve dynamic light scattering is disclosed. An example laser dither and correlator synchronizing system includes a laser driver configured to output a laser. The example laser dither and correlator synchronizing system further includes a correlator having an internal clock. The example laser dither and correlator synchronizing system further includes a waveform generator configured to receive a clock signal from the internal clock of the correlator, receive a dither signal from a controller, and output a laser modulation signal to the laser driver based on the dither signal and the clock signal.