Abstract: We suggest a modification of a single-beam optical trapbuilt in a conventional microscope (not the invertedone). Our enhancement of the trapping efficiencyconsists of a highly-reflective-layers-coated glassplate forming the bottom of the sample cell. Usingthis, we obtain a combination of two beams - theincident one propagating downward and the reflected onepropagating upward - which together create an effectivemicroobject trap. Using the micron-size polystyrenespheres we have experimentally proved that it is easyto achieve an efficient 3D trapping using even highlyaberrated beams although the single beam trap does notwork in this case. The interference of the incident andreflected beams forms a standing wave which isespecially useful for nanoobjects trapping. Nanoobjectsof diameters equal to tens of nanometers are stablytrapped near the antinodes (intensity maxima) of thestanding wave due to the restoring dipole force whichis thousands times greater than the scattering force inthis case. The paper presents the qualitativedescription of the trapped object behavior, theoreticalstudy and calculations of forces acting on themicroobjects and nanoobjects. The influence of thestanding wave on the observed microsphere behavior isalso discussed.!22
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