Intensity uniformity improvement for a complex line beam

Abstract

A complex line beam, whose intensity distribution is uniform along a line shape and phase distribution is linearly gradient, can be applied in automatic directional transportation and optical separation of microparticles. Generally, complex amplitude beam shaping methods are used to control both the amplitude and phase of an output beam with a single phase-only element. However, for the complex line beam, although the phase gradient can be controlled well, the intensity of the beam is unevenly distributed, i.e. most of the energy of the beam is distributed in the two ends of the lateral direction. In this paper, we propose an intensity-compensation method based on the complex amplitude beam shaping method, in which the target intensity distribution of the output beam is modulated with a Gaussian profile on purpose. The simulation and experimental results show that the intensity uniformity of the complex line beam has been increased by 80.6% while the phase of the beam has been controlled as linearly gradient.