| 1. |
- Arias, Augusto, et al.
(författare)
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Simultaneous rotation, orientation and displacement control of birefringent microparticles in holographic optical tweezers
- 2013
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 21:1, s. 102-111
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Tidskriftsartikel (refereegranskat)abstract
- We report the experimental implementation of a new method for generating multiple dynamical optical tweezers, where each one of them is generated with an independent linear polarization state with arbitrary orientation. This also allows an independent simultaneous polarization-rotation control. The laser beam, both for generating multiple traps and polarization control, has been modulated using a single reflective nematic liquid crystal with parallel alignment. We present experimental results of controlled displacement, orientation and rotation of birefringent particles. In addition, a simple method for estimating and canceling out the primary astigmatism present in the system is presented.
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| 2. |
- Magazzu, Alessandro, et al.
(författare)
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Controlling the dynamics of colloidal particles by critical Casimir forces
- 2019
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Ingår i: Soft Matter. - : Royal Society of Chemistry (RSC). - 1744-683X .- 1744-6848. ; 15:10, s. 2152-2162
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 The Royal Society of Chemistry. Critical Casimir forces can play an important role for applications in nano-science and nano-technology, owing to their piconewton strength, nanometric action range, fine tunability as a function of temperature, and exquisite dependence on the surface properties of the involved objects. Here, we investigate the effects of critical Casimir forces on the free dynamics of a pair of colloidal particles dispersed in the bulk of a near-critical binary liquid solvent, using blinking optical tweezers. In particular, we measure the time evolution of the distance between the two colloids to determine their relative diffusion and drift velocity. Furthermore, we show how critical Casimir forces change the dynamic properties of this two-colloid system by studying the temperature dependence of the distribution of the so-called first-passage time, i.e., of the time necessary for the particles to reach for the first time a certain separation, starting from an initially assigned one. These data are in good agreement with theoretical results obtained from Monte Carlo simulations and Langevin dynamics.
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