Measurement of the trapping efficiency of an elliptical optical trap with rigid and elastic objects

Optical tweezers and their various modifications offer a sophisticated way to perform noncontact cell manipulation. In this paper, we quantify forces existing in an elliptical trap formed by two cylindrical lenses and compare the results with a point optical trap case. The trapping efficiency of point and elliptical traps was analyzed by measuring the Q values of both traps. Polystyrene microspheres and red blood cells (RBCs) were used as samples. Stretching of the RBC was taken into account in the Q value measurements. Although the Q value of a point optical trap is larger than that of an elliptical trap when measured for a single RBC, we can manipulate the orientation of an RBC in a point trap with the elliptical trap and can also trap several RBCs simultaneously in the elliptical trap far from the cuvette surfaces by using a long-working-distance water immersion objective. This opens new possibilities for studying light-matter interactions at the cellular level.