Optothermal Traps Based on Mosaic Phase Masks

The expansion of the functionality of optothermal traps through the use of mosaic diffraction elements has been experimentally demonstrated. The phase functions of simple optical elements are used to form mosaic (sector, ring, and their combinations) phase masks. For the first time, a controlled rotation of ensembles of microparticles in optothermal traps of various shapes has been implemented. It is shown that during rotations with velocities of 2.7–6.5 deg/s, latex microparticles with dimensions of 3–4 μm are held in optothermal traps.