Fig. 4.

Combined acoustic and optical trapping of micro-organisms (Euglena gracilis). Shown is a direct-view image, selected from Media 2 ^{(4.1MB, MOV)} . The acoustic trap confines all micro-organisms within the focal plane. A single organism (marked by a circle) is trapped in the optical trap. It aligns along the (vertical) laser beam and appears point-like. Within 40 s the optical trap has been moved by a distance of about 1 mm, dragging the organism across the field of view.