Beam shaping of partially coherent light beams

Abstract

Laser beams with a uniform profile or other kinds of profiles are desired in many applications, such as in laser fusion, laser heat treatment, and optical data proceeding etc.. Unfortunately a laser operated in TEM00 mode delivers a laser beams with a Gaussian profile. Therefore it is very important to reshape a laser beam with a profile to the desired profile. In addition, partially coherent light beams have become of interest in recent years. This is due to the fact that a laser beam with many transverse modes can be described by a partially coherent light beam, and partially coherent light beams have found applications in laser fusion, in which a highly coherent light beam is transformed into a partially coherent light beam, for reducing the speckle and getting the more smooth focusing spot. However until now, the most of study on the beam shaping is concerning the beam shaping of spatially completely coherent light beam, little work has been done on the beam shaping of partially coherent light beams. In present paper, we investigate the beam shaping of partially coherent light beam by modulating the spectral coherence of the partially coherent light beam. Some special focusing spots, such as an annulus, or an flattened annulus, or a uniform profile, can be achieved by modulating the spatial coherence of the beam to a particular value.