Study On The Doughnut Beam Generated By Liquid Crystal Cell

Optical tweezer is a promising technology which offers great opportunity for life sciences and cut-in point for the combination, new experimental technology and life basic problems of the physics and life subject. It has play important role in the research of the several basic life problems.The dissertation is mainly on the research of the trapping beam used as optical tweezer. We use a new method which is based on a newly designed liquid crystal cell. The method is easy to apply and has high conversion efficiency. It is also dynamically tunable over the visible and near-infrared wavelength range.The main theoretical work can be concluded as follows:1. I setup calculation model of the phase of the liquid-crystal cell and calculate the phase change related to the voltage.2. the simulation and calculation of the lauerre-gaussian mode.3. the far field calculation of the intensity by Fourrier transform.4. the theoretical simulation of interference of a plane wave and doughnut beamThe main experimental work is to generate the doughnut beam with charges l=1 and l=2.