Roughness measurement of oriented surface by depolarization of scattered light

Surface roughness is generally a constituent of surface texture and determines the interaction of the material and its environments. Thus, it has recently become a significant parameter in optimizing material properties and functionality. Consequently, surface roughness influences material structures and morphology thus a crucial consideration in industrial applications. Recently, surface roughness in materials has attracted significant attention of researchers. To this note, several approaches have been developed to investigate the various properties and characterization of surface roughness and their influence on material properties and applications. Amongst the characterization parameters, average roughness stands out.

Recent studies have shown great approaches including optical methods that have enhanced resolution, sensitivity and ensuring no surface damage through effective vibration prevention. On the other hand, surface roughness measurement techniques utilizing light scattering such as speckle patterns have been used in speckle pattern analysis as well as investigation of the surface properties. Unfortunately, the application of the cross-polarization ratio analysis in oriented surfaces is still missing.

To this note, Federal Fluminense University scientists led by Professor Huguenin investigated the intensity of depolarized light scattered by oriented rough surfaces. In particular, they cross-examined the initially developed cross-polarization ratio method for random rough surfaces and modified it to suit application in oriented rough surfaces. Their fascinating research work is currently published in the research journal, Optics and Lasers in Engineering.

In brief, the study entailed: a polarized laser beam that was used to produce scattered light with a different surface roughness in two different ranges of interval 1.4-2.6 µm and effective monitoring of the depolarized light at normal directions. Next, the influence of the intensity of the depolarized light on the mean roughness was further investigated. To actualize their study, they eventually explored the possibility of using the obtained results in real-time control of metallic surface roughness.

The authors observed that the cross-polarization ratio analysis technique was not only applicable to random rough surfaces but also oriented rough surfaces. In addition, the results instigated that the depolarized technique was useful in evaluating inverse roughness with minimal additional calculations and data processing. Furthermore, further analysis of the lower roughness range indicated an increment of the coefficient cross-polarization ratio and depolarized signal with respect to the surface roughness thus signifying the significance of the incident laser power.

In summary, the study presented a successful application of the cross-polarization ratio analysis for oriented rough surfaces. For instance, they pointed out that the technique can be used for a variety of materials and particularly metallic surfaces owing to their excellent reflectance properties capable of increasing the scattered light signal. It was also seen that the technique could effectively control the surface roughness in real time. Altogether, their work brings forward the necessary improvements that will advance numerous industrial applications including production lines.