Optical trapping and manipulation of microscopic particles and biological cells by laser beams

Optical trapping incorporating visible and near-IR laser beams has become an important tool for precise, noncontact manipulation of various micrometre-sized particles. This paper reviews basic principles and features of single-beam optical trapping of microscopic particles such as biological cells, polystyrene latex spheres, small crystals and metal particles. Trapping forces measured and calculated on the basis of ray optics are discussed. Some interesting applications are also described, including an optical micromotor, all-optical biological cell fusion, observation of nonlinear optical phenomena and microlaser oscillation, and metal particle trapping.