涡旋光束经过散射介质产生散斑的理论和实验研究

Investigation on the speckle produced by vortex beams through a scattering medium

研究了涡旋光束经过散射介质后形成的散斑特性.运用概率统计理论和光束传输理论,模拟了不同拓扑电荷数的涡旋光束经过散射介质后形成的散斑,以及散射介质颗粒尺度对散斑特性的影响。模拟结果表明,随着涡旋光束拓扑电荷数的增大和散射介质颗粒尺度减小,形成的散斑颗粒尺寸逐渐减小。实验上,利用螺旋相位板(SPP)产生涡旋光束,使其透过散射介质后形成散斑。实验结果表明,涡旋光束经过散射介质后,随着散射介质颗粒尺度减小,形成的散斑对比度逐渐增大;随着涡旋光束拓扑电荷数的增大或散射介质颗粒的减小,所形成散斑的尺寸减小。实验结果与模拟结果相吻合。

Theoretical and experimental study on the speckle properties formed by propagating vortices beams probability through scattering medium is demonstrated. Based on the theory and beam transmis- sion theory,we simulate different topological charges of speckle formed by vortex beams. The effects of scattering medium particle size on the speckle characteristics are analyzed. The calculated results show that the speckle sizes formed by vortex beams through scattering medium are smaller than those of the Gaussian beam,and the speckle sizes will reduce with increasing topological charge of vortex beam or de- creasing the particle size of the scattering medium. In experiment, the speckle is obtained by vortex beams propagating generated by spiral phase plate through a scattering medium. The results show that the speckle contrast increases with decrease of the particle size of the scattering turbid medium. Experi- mental results agree well with theoretical simulation. The results have very important potential applica- tions to bio-medical imaging,and also material detection.