LASER MANIPULATION BY USING LIQUID CRYSTAL DEVICES WITH VARIABLE-FOCUSING AND BEAM-STEERING FUNCTIONS

摘要

A laser manipulation system for trapping and controlling the positions of microscopic transparent particles by using liquid crystal (LC) devices is developed. The LC device has functions of variable-focusing and beam-steering by controlling the applied voltages to the LC device without mechanical movements. The trapped particles suspended in deionized water can easily be shifted along the position of the focused laser spot. The microscopic rod-like particles can also be shifted and rotated in the clockwise or anticlockwise along the direction of the major axis of the elliptically distributed beam intensity. In addition, the multiple microscopic particles at the bright region of the linear interference fringe patterns of the LC device with comb-shaped electrodes can be trapped and shifted along the fringe patterns.