Force measurement on microspheres in an optical standing wave

Optofluidic Near-Field Optical Microscopy: Near-Field Mapping of a Silicon Nanocavity Using Trapped Microbeads

“…The existence of different trapping regimes in optical lattices was already investigated in previous studies, − where it has mainly found applications in microparticles optical sorting. However, it is here observed and analyzed for the first time in the near-field of a photonic nanostructure that enables high three-dimensional spatial light confinement.…”

“…When decreasing the bead’s size from 2 μm to 500 nm in diameter, we observe a clear transition from an “averaged” trapping regime toward a “proportional” trapping regime. In light of the literature, it appears that this “size-effect” occurs here for unexpectedly large microbead’s sizes. − We also analyze how a variation of the input laser power and, thus, of the depth of the potential well impacts the “effective” shape of the trap. In light of those results, we eventually discuss the concept of optofluidic near-field optical microscopy: an original approach to image evanescent fields at the nanoscale via the thermal motion of optically trapped fluorescent microprobes.…”

Optorheological thickening under the pulsed laser photocrosslinking of a polymer

“…Typically, this is resolved with confocal microscopy; however, this is a slow process if multiple particles are to be tracked. In this study, Brownian motion was restricted to one dimension by creating a two dimensional optical trap within the solution. The trap confined the particles to the imaging region while leaving the solution itself undisturbed.…”

Optical sorting in holographic trap arrays by tuning the inter-trap separation

“…fluorescence, size) and subsequent application of optical forces to sort selected particles into desired channels [2][3][4][5][6]. On the other hand, passive sorting makes use of the difference in the optical forces on particles varying in their size and refractive index, to cause angular separation in particles flowing through an optical landscape that can be generated by techniques such as interferometric [1,[7][8][9][10][11][12][13], holographic [14][15][16][17][18] and acousto-optic optical tweezers [19]. Since under these schemes particles are separated by introducing a deflection to the selected subpopulation from the original flow direction, the resulting angular separation between the different subpopulations is an important parameter as larger angular separation would result in a more effective separation within a small distance.…”