Rotational manipulation of trapped micro-objects about their axes perpendicular to the laser beam axis by radiation pressure

The development of optical trapping by a single focused laser beam, also known as optical tweezers (1) has made it possible to manipulate various particles including biological cells, metallic particles (2), and low-refractive-index micro-objects (3). Recently, the application of optical trapping to rotational manipulation of artificial micro-objects in micro-mechanical systems (4) was repress. Rotation was due to the optical torque from the optical radiation pressure exerted on the outside of micro-objects that had shape anisotropy. The axis of this rotation coincided with the incident laser beam axis (2, 4, 5). In an effort to change the direction of the optically induced torque, this paper investigates the possibility of optical trapping and simultaneous rotation about an axis perpendicular to the incident laser beam axis by illuminating an object with a strongly focused laser beam.