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Articles you may be interested inHigh resolution heterodyne interferometer based on time-to-digital converter Rev. Sci. Instrum. 83, 045112 (2012); 10.1063/1.4704357 Note: Phase compensation in the fiber optical quadrature passive demodulation scheme Rev. Sci. Instrum. 81, 046108 (2010); 10.1063/1.3397255 Novel phase measurement technique of the heterodyne laser interferometer Rev. Sci. Instrum. 76, 093105 (2005); Intrinsic fiber-optic ultrasonic sensor array using multiplexed two-wave mixing interferometry AIP Conf. Proc. 615, 915 (2002);ABSTRACT. The new interferometric scheme that was presented at last year QNDE conference for robust and sensitive detection of ultrasound in industrial environment has been further improved. The proposed architecture combines quadrature detection with detector arrays for multi-speckle processing. The quadrature is reached tanks to the random phase distribution of the speckle light and the parallel signal processing is simplified by using an approximated demodulation technique based on signal rectification. Results demonstrating this new principle of operation and its performances are presented.

The potential application of multispectral polarization imaging for detection and recognition requires a good knowledge of the depolarizing behavior of targets. We measured the degree of polarization associated to several targets in a monostatic configuration as a function of wavelength and of the angle of incidence. Depolarization effects depending on the absorption of targets were observed and a phenomenological model based on Kubelka-Munk theory is proposed. It describes the behavior of paints and diffuse materials, taking into account both contributions of surface scattering and volume scattering. Target parameters such as roughness, refractive index, scattering coefficient are taken into account and enable to draw out a predictive model of the depolarizing behavior of targets. We found a good agreement between measurements and our predictions.

SynopsisHair luster is one of the most important parameters of visual appearance perceived by consumers. Current luster formulae (TRI, Reich-Robbins, ...) are optimized for goniophotometric measurements. They are based on a mathematical decomposition of reflected light into specular and diffused light and the measurement of the shine peak width on the fitted angular distributions. In this expose, we are describing a polarization imaging system measuring luster of hair tresses with an innovative algorithm. Using polarization imaging allows to physically separating the specular light from the diffused light for each pixel of the imaged tress. Angular distributions of the specular and diffused light are obtained in a few seconds. Where conventional methods calculate the shine peak width on the angular distribution, the imaging system imitates the human eye and calculates the shine width directly on the image. The new formula combines different measured parameters to objectively quantify luster. It was designed to exhibit a higher correlation with visual perception along with a higher sensitivity. Results obtained with conventional formulae are compared on different hair tresses, treated and untreated. The new formula is found to be consistent for a whole range of hair colors, from light to dark.

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