Random depth access full-field heterodyne low-coherence interferometry utilizing acousto-optic modulation and a complementary metaloxide semiconductor camera

With analog scanning, time-domain low-coherence interferometry lacks precise depth information, and optical carrier generation demands a linear scanning speed. Full-field heterodyne low-coherence interferometry that uses a logarithmic complementary metal-oxide semiconductor camera, acousto-optic modulation, and digital depth stepping is reported, with which random regions of interest, lateral and axial, can be accessed. Furthermore, nanometer profilometry is possible through heterodyne phase retrieval of the interference signal. The approach demonstrates inexpensive yet high-precision functional machine vision offering true digital random access in three dimensions.     

Feasibility study of a digital speckle pattern interferometry and bending test combined technique to investigate coating adhesion

This paper presents a feasibility study to assess whether digital speckle pattern interferometry could be used as a possible technique to investigate the adhesive performance of coatings. The approach is based on the measurement of the deflections produced by a pre-notched coated specimen subjected to a four-point bending test. When the bending load is increased, a delamination between the coating and the substrate is propagated with its length depending on the adhesion strength. Experiments carried out with specimens having simulated delaminations confirm that digital speckle pattern interferometry can be used to estimate the delamination length.     

Evolution of the Raman backscattered intensity used to analyze the micromechanisms of deformation of various polypropylene blends in situ during a uniaxial tensile test

This paper presents a study of the evolution of the Raman backscattered intensity used to follow the modifications of polymer microstructure in real time during a tensile test. The context of this study is the coupling of the VideoTraction™ system with a Raman spectrometer, which has already led to in‐situ measurements of molecular chains orientation and crystallinity. The polypropylene blends will be characterized optically at the same probing wavelength by incoherent light scattering to understand phenomena enlightened by Raman spectroscopy. Then, a discussion on the Raman intensity evolution is conducted, with the possible contribution of Raman spectroscopy to describe stages of the volume damage micromechanism. Copyright © 2014 John Wiley & Sons, Ltd.