  We demonstrate optical trapping and manipulation of defects and transparent
microspheres in nematic liquid crystals (LCs). The three-dimensional director
fields and positions of the particles are visualized using the Fluorescence
Confocal Polarizing Microscopy. We show that the disclinations can be
manipulated by either using optically trapped colloidal particles or directly
by tightly-focused laser beams. We employ this effect to measure the line
tensions of disclinations.
