Passos M H M, Lemos M R, Almeida S R, Balthazar W F, da Silva L, Huguenin J A O
Appl Opt. 2017 Jan 10;56(2):330-335. doi: 10.1364/AO.56.000330.
In this work, we report on the analysis of speckle patterns produced by illuminating different rough surfaces with an optical vortex, a first-order (l=1) Laguerre-Gaussian beam. The generated speckle patterns were observed in the normal direction exploring four different planes: the diffraction plane, image plane, focal plane, and exact Fourier transform plane. The digital speckle patterns were analyzed using the Hurst exponent of digital images, an interesting tool used to study surface roughness. We show a proof of principle that the Hurst exponent of a digital speckle pattern is more sensitive with respect to the surface roughness when the speckle pattern is produced by an optical vortex and observed at a focal plane. We also show that Hurst exponents are not so sensitive with respect to the topological charge l. These results open news possibilities of investigation into speckle metrology once we have several techniques that use speckle patterns for different applications.
在这项工作中，我们报告了用光学涡旋（一阶（l = 1）拉盖尔 - 高斯光束）照射不同粗糙表面所产生的散斑图案的分析情况。在法线方向上通过探索四个不同平面观察所产生的散斑图案：衍射平面、图像平面、焦平面和精确傅里叶变换平面。使用数字图像的赫斯特指数对数字散斑图案进行分析，赫斯特指数是用于研究表面粗糙度的一个有趣工具。我们证明了一个原理，即当散斑图案由光学涡旋产生并在焦平面观察时，数字散斑图案的赫斯特指数对表面粗糙度更为敏感。我们还表明，赫斯特指数对拓扑电荷l不太敏感。一旦我们有多种将散斑图案用于不同应用的技术，这些结果为散斑计量学的研究开辟了新的可能性。
