Date of Award
Summer 2026
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Physics
College
College of Science and Health
First Advisor
Eric Landahl
Abstract
Dynamic light scattering (DLS) determines particle size from temporal fluctuations in coherently scattered light. Here a field-programmable gate array (FPGA) computes intensity autocorrelations in real time, and an automated diffractometer with custom 3D-printed cuvette, laser, homing, and GT2-gear mounts enables multi-angle measurements. Square-wave timing tests at 1 Hz, 100 Hz, and 10 kHz verified the correlator response. Calibrated latex spheres were then measured at seven scattering angles from 32.5◦ to 44.5◦. Each autocorrelation function was fit to the standard single-exponential form g(τ ) = B + βe−2Γτ with weights from analytic per-lag Poisson uncertainties σg = pg/N based on coincidence counts. The extracted decay rates Γ varied linearly with q2, yielding diffusion coefficients and hydrodynamic diameters of 94 ± 8, 397 ± 28, and 556 ± 64 nm for latex spheres of nominal size 90, 300, and 490 nm. Motor-induced noise was identified and removed by disabling the stepper drive during acquisition. These results support FPGA-based real-time correlation as a viable approach for quantitative multi-angle DLS at the proof-of-concept level.
Copyright
Copyright © 2026 Spiros Simotas
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Simotas, Spiros, "Multi-Angle Dynamic Light Scattering Experiments With Real-Time Autocorrelation Using Field-Programmable Gate Arrays" (2026). Theses and Dissertations from DePaul University. 131.
https://via.library.depaul.edu/theses-dissertations/131