Non-diffracting effect of partially blocked annular beam propagating in scattering media

Laser beam propagation in highly scattering media has attracted much attention for optical sensing fields. To further explore the characteristics of beam propagation, we investigate the propagation property of an annular beam in a highly scattering media for increasing the sensing limitation in such scattering conditions. In this work, propagation of partially blocked annular beam in free space is simulated to show self-transformation of non-diffractive beam which keeps its main central energy up to far lengths. Using a fan-like obstacle with different apex angles, propagation experiments of partially blocked annular beam in scattering media were conducted. The scattering light is measured at different receiving distances to demonstrate that the central peak intensity of this scattered light is a non-diffractive beam. We discussed that the change of the intensity profile of scattered light can be used to infer the position and the relative sizes of the obstacles. (author)