OPTICALLY INDUCED ROTATION OF A TRAPPED MICRO-OBJECT ABOUT AN AXIS PERPENDICULAR TO THE LASER-BEAM AXIS

A strongly focused Nd:YAG laser beam has been used experimentally to a chieve optical trapping and simultaneous rotation of a micro-object ab out an axis perpendicular to the trapping laser beam axis. The micro-o bject (12 mu m in diameter), which has shape anisotropy in its interio r, can be produced by oxygen reactive ion etching of a fluorinated pol yimide film (refractive index n = 1.53). This optically induced rotati on of the micro-object in ethanol (n = 1.36) is accomplished by utiliz ing the net radiation pressure force arising from the momentum change of light scattered at the micro-object's inner walls. (C) 1998 America n Institute of Physics.