Speckle patterns produced by an optical vortex and its application to surface roughness measurements.

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.

[1]  J. Leendertz,et al.  Interferometric displacement measurement on scattering surfaces utilizing speckle effect , 1970 .

[2]  Héctor Rabal,et al.  Analysis of bacterial chemotactic response using dynamic laser speckle. , 2009, Journal of biomedical optics.

[3]  J. Goodman.  Some fundamental properties of speckle , 1976 .

[4]  Andrew G. White,et al.  Generation of optical phase singularities by computer-generated holograms. , 1992, Optics letters.

[5]  C S Ih,et al.  Feature information extraction from dynamic biospeckle. , 1994, Applied optics.

[6]  Xuyuan Chen,et al.  Speckle reduction in laser projection using a dynamic deformable mirror. , 2014, Optics express.

[7]  D. P. Caetano,et al.  Effect of metallic surface roughness on the speckle pattern formation at diffraction plane , 2012 .

[8]  A. E. Ennos,et al.  IV Speckle Interferometry , 1978 .

[9]  U. Persson,et al.  Surface Roughness Measurement on Machined Surfaces using Angular Speckle Correlation , 2006 .

[10]  J. Huguenin,et al.  Tsallis threshold analysis of digital speckle patterns generated by rough surfaces , 2015 .

[11]  Mitsuo Takeda,et al.  Optical vortex metrology based on the core structures of phase singularities in Laguerre-Gauss transform of a speckle pattern. , 2006, Optics express.

[12]  Bernard Le Jeune,et al.  Retrieving controlled motion parameters using two speckle pattern analysis techniques: spatiotemporal correlation and the temporal history speckle pattern. , 2013, Applied optics.

[13]  Salla Gangi Reddy,et al.  Higher order optical vortices and formation of speckles. , 2013, Optics letters.

[14]  D B Barker,et al.  Measuring fluid velocities with speckle patterns. , 1977, Optics letters.

[15]  J. Huguenin,et al.  Hurst exponent determination for digital speckle patterns in roughness control of metallic surfaces , 2011 .

[16]  D. P. Caetano,et al.  Fractal structure of digital speckle patterns produced by rough surfaces , 2013 .

[17]  X. Orlik,et al.  Polarized vortices in optical speckle field: observation of rare polarization singularities. , 2015, Optics express.

[18]  D. P. Caetano,et al.  Hurst exponent analysis of moving metallic surfaces , 2013 .

[19]  V. Tuchin,et al.  Blood-flow measurements with a small number of scattering events. , 2000, Applied optics.

[20]  Dayan Li,et al.  Speckle suppression by doubly scattering systems. , 2013, Applied optics.

[21]  N. Halliwell,et al.  Laser speckle photography and particle image velocimetry: photographic film noise. , 1984, Applied optics.

[22]  J. P. Woerdman,et al.  Astigmatic laser mode converters and transfer of orbital angular momentum , 1993 .

[23]  K Wolff,et al.  Corrosion monitoring with speckle correlation. , 1999, Applied optics.

[24]  Hasan Öktem,et al.  Measurement of surface roughness of metals using binary speckle image analysis , 2010 .