Križna diferenčna dinamična mikroskopija

Arko, Matej (author), Mertelj, Alenka (mentor), Petelin, Andrej (comentor)

V magistrskem delu je kot razširitev osnovne metode diferenčne dinamične mikroskopije za namen opazovanja hitre dinamike v mehki snovi predstavljena metoda križne diferenčne dinamične mikroskopije. V običajni metodi poteka zajemanje videoposnetka fluktuacij intenzitete sipane svetlobe v vzorcu pri konstantni frekvenci zajemanja slik, zato je najmanjši časovni zamik med dvema slikama obratno sorazmeren s frekvenco. V novi metodi z uporabo dveh poravnanih kamer pridobimo dva nabora slik istega dela vzorca, s Fourierovo analizo pa izračunamo križno slikovno strukturno funkcijo kot funkcijo valovnega vektorja in časovnega zamika. Naključna shema proženja kamer poskrbi, da lahko najmanjši časovni zamik med dvema slikama poljubno skrajšamo ter tako efektivno povečamo frekvenco zajemanja, zato lahko dinamiko v mehki snovi opazujemo tudi v primeru hitrih procesov. Z meritvijo dinamike nematičnega tekočega kristala ter s simulacijami Brownovega gibanja sferičnih delcev smo preučili razlike med obema metodama, z namernim izmikanjem obeh kamer iz poravnane lege pa preverili robustnost križne diferenčne dinamične mikroskopije.

• Language: Slovenian
• Keywords: mikroskopija, sipanje svetlobe, termične fluktuacije, tekoči kristali
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FMF - Faculty of Mathematics and Physics
• Year: 2019
• PID: 20.500.12556/RUL-113148
• COBISS.SI-ID: 3391076
• Publication date in RUL: 07.12.2019

ARKO, Matej, 2019, Križna diferenčna dinamična mikroskopija [online]. Master’s thesis. [Accessed 29 June 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=113148

Secondary language

• Language: English
• Title: Cross differential dynamic microscopy

Abstract

In this master's thesis Cross-Differential Dynamic Microscopy is introduced as an extension to the established method of Differential Dynamic Microscopy, for the purpose of observing the fast dynamics in soft matter. With the standard method, a video of the fluctuating intensity of light, scattered by the observed sample, is taken at a constant frame rate. The smallest time delay between two consecutive frames is therefore inversely proportional to the frame rate. With the new method we obtain two sets of data, taken with two aligned cameras observing the same area in the sample, and we calculate the cross-image structure function as a function of the wave vector and the time delay. Random triggering of the cameras can greatly decrease the minimum time delay between the two frames, which results in a faster effective frame rate. This way we can observe the dynamics of fast processes in soft matter. In the experiment we compared both the standard and the new method by measuring the dynamics of a nematic liquid crystal and by analyzing simulated videos of Brownian motion of spherical particles. Lastly, robustness of the proposed method was tested against various camera misalignments.

• Keywords: microscopy, light scattering, thermal fluctuations, liquid crystals