超快激光散斑场的时空相干特性

TEMPORAL AND SPATIAL COHERENCE PROPERTIES OF ULTRAFAST LASER SPECKLE FIELDS

将超快激光应用到对散斑现象的研究领域.首先从散斑统计理论和光的相干性角度出发,给出入射飞秒脉冲的自相关函数分布及光强经过粗糙随机表面后的光强演化形式.从实验上通过用飞秒激光脉冲光源照射粗糙的随机表面衍射屏,得到了一系列明显区别于传统普通的连续光形成的散斑场.在超快散斑场中出现了纤维辐射状的结构,散斑图样整体呈由中心光斑状向四周辐射形成条纹状光斑的分布.

We used ultra-fast lasers to study the speckle phenomenon. Based on the theory of speckle statis- tics and the coherence of light, the self-correlation function distribution and the light intensity evolution of the inci- dent femtosecond pulse were given. From the experimental results by use of femtosecond laser pulse light illuminat- ing rough random surface screens, we found that the speckles were quite different from the traditional common con- tinuous light speckle field, and the ultrafast laser speckle field was observed to be with the structures of the fiber ra- dial, porphyritic speckle pattern by the center on the whole light radiation form stripes intensity distribution.