Creation, transportation, and coalescence of liquid drops by means of a light beam

A novel principle of manipulation of discrete drops using concentration-capillary forces controlled by the thermal action of a light beam is proposed. The drops are created by the light beam in a thin layer of absorbing solution and in a film of that solution beneath an air bubble in the cell. The possibility of transporting both a single drop and a drop in an air bubble by means of a light beam is demonstrated. For the first time two drops are made to coalesce on a solid substrate by bringing them into contact by means of a light beam.