Optical tweezers: theory and practice
Department of Physics, Università degli di Studi di Napoli “Federico II” Complesso Universitario Monte S. Angelo, Via Cintia, 80126, Naples, Italy
2 Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, London, UK
3 CNR-IPCF, Istituto Processi Chimico-Fisici, V.le F. Stagno D’Alcontres 37, 98158, Messina, Italy
4 Department of Physics, University of Gothenburg, 41296, Gothenburg, Sweden
Accepted: 6 October 2020
Published online: 7 December 2020
The possibility for the manipulation of many different samples using only the light from a laser beam opened the way to a variety of experiments. The technique, known as Optical Tweezers, is nowadays employed in a multitude of applications demonstrating its relevance. Since the pioneering work of Arthur Ashkin, where he used a single strongly focused laser beam, ever more complex experimental set-ups are required in order to perform novel and challenging experiments. Here we provide a comprehensive review of the theoretical background and experimental techniques. We start by giving an overview of the theory of optical forces: first, we consider optical forces in approximated regimes when the particles are much larger (ray optics) or much smaller (dipole approximation) than the light wavelength; then, we discuss the full electromagnetic theory of optical forces with a focus on T-matrix methods. Then, we describe the important aspect of Brownian motion in optical traps and its implementation in optical tweezers simulations. Finally, we provide a general description of typical experimental setups of optical tweezers and calibration techniques with particular emphasis on holographic optical tweezers.
© The Author(s) 2020
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