Experiment of vertex beam generated by method of computer generated holography

Based on the computer generated holography, the dislocation fringes caused by the interference between the vortex beam and the plane beam were obtained through simulation and expriment. The dislocation gratings were made by films which recorde these interference fringes. With our own designed optical path, 1-4 order vortex beam were obtained in the experiment. The experimental results show that radius of the vortex beam will increase gradually with the increasing the orders, which are consistent with the theoretical analysis. The second and third diffraction beams of the gratings are observed further in the experiment. The vortex beam of symmetrical intensity distribution can be produced when the center of incent beam overlaps with the cetnter of dislocation grating, otherwise, the distribution of the vortex beam will be asymmetrical if the center of incent beam does not overlap with the center of dislocation grating. This work provides theoterical and technical support for further development of the optical tweezers based on vortex beam as the trapping beam.