New publication in ACS Photonics!

27.06.2024

Unified Simulation Platform for Interference Microscopy

Felix Hitzelhammer, Anež ka Dostálová, Ilia Zykov, Barbara Platzer, Clara Conrad-Billroth, Thomas Juffmann, and Ulrich Hohenester
ACS Photonics (2024), DOI: 10.1021/acsphotonics.4c00621

 

Abstract:

Interferometric scattering microscopy is a powerful technique that enables various applications, such as mass photometry and particle tracking. Here, we present a numerical toolbox to simulate images obtained in interferometric scattering, coherent bright-field, and dark-field microscopies. The scattered fields are calculated using a boundary element method, facilitating the simulation of arbitrary sample geometries and substrate layer structures. A fully vectorial model is used for simulating the imaging setup. We demonstrate excellent agreement between our simulations and experiments for different shapes of scatterers and excitation angles. Notably, for angles near the Brewster angle, we observe a contrast enhancement which may be beneficial for nanosensing applications. The software is available as a matlab toolbox.

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(a) In our simulations, we consider a substrate or stratified medium that is excited by incoming fields. (b) Optical response of an additional nanoparticle, here a gold nanosphere, is obtained from a BEM solver. The boundary of the nanoparticle is discretized through triangular boundary elements, and by solving the BEM working equations, the tangential electromagnetic fields at the particle boundary, which fully

characterize the solution, are obtained. (c) From the BEM solutions, we can compute the optical far fields, which are imaged using the Richards−Wolf approach. Through the superposition of the imaged (d) reference and (f) scattering fields, we finally obtain the (e) interference image that can be directly compared with results of iSCAT experiments.