角分辩的光散射轮廓及自仿射分形表面的粗糙指数的实验研究

Experimental Study on Angle-resolved Light Intensity Scattered Profile and Roughness Exponent of Self-affine Fractal Surface

建立了反射式随机表面的光散射特性实验测量系统,利用多幅平均及叠加连接的方法,得出入射角在45°～85°之间不同值时的光散射轮廓。结果表明,随着表面入射角的增加,光散射轮廓的半峰全宽逐渐减小。并且当入射角的增加到一定值时,光散射轮廓出现中央亮斑。由数学上的对称下降函数,推导出光散射轮廓的半峰全宽随散射光波矢的变化关系,从实验测得角分辩的的光散射轮廓中提取了自仿射分形随机表面的粗糙指数。与原子力显微镜测量得到的粗糙指数进行比较,两者符合得很好。

The new experimental measurement system is set up to measure light intensities scattered from the reflection-mode random surface. By using the technique of data average and overlay connection, the functions of scattered light intensity profiles are calculated at different incidence angles （45°- 85°） on random surface. The results show that the full widths at half-maximum of intensity profiles are decreased gradually with increased of the incidence angles. While the incidence angle increases to a certain value, the light intensity scattered profile presents a central bright spot. Based on the symmetric decline function in mathematics, the relationship between the full width at half-maximum of intensity profile and the light wave vector is deduced, and the roughness exponent of selfaffine fractal surface is extracted from angle-resolved scattered light intensity profiles. It is obvious that the obtained value of roughness exponent is in good agrement with that measured by atomic force microscop.