Although no study has confirmed a relationship between the penetration depth of root canal sealers and the prevention of apical periodontitis, dentinal tubule sealer penetration may improve obturation quality.

The temporal frequency response of water supplemented with scattering particles was deduced from the measurement of the optical backscattering of a short (100 ps) blue-green (532 nm) optical pulse given by a frequency-doubled Nd:YAG laser. Indeed, this backscattering measurement gave the water impulse response from which the transfer function was computed by taking the power spectrum. This backscattering frequency response had a low-pass filter-like response which enabled us to estimate the medium cut-off frequency. As the backscattered signal shape depends on the value of the water attenuation coefficient, the ocean water cut-off frequency varies with the amount of scattering particles its contains. The aim was to define the variations of the cut-off frequency as a function of the attenuation coefficient.

This paper reports monitoring fruits maturation using speckle technique. Performed measurements aim the assessing of biological inner fruit variation effect on the speckle image. We show that the speckle grain size is both affected by the glucose level inside the fruits and by the chlorophyll content. Moreover, the determination of circular polarization degree and circular grain size indicate that a Rayleigh diffusion regime gradually becomes predominant in fruits. Principal component analysis is used to highlight high correlation between results and strengthen the establishment of speckle as a novel non invasive method to monitor fruits ripening.

We have experimentally assessed the efficiency of a new underwater-target detection scheme, called modulated lidar. The technique used is based on a remarkable physical property of the propagating medium; sea-water has a low-pass transfer function in backscattering configuration. As the target return is less frequency-dependent, the use of a radio frequency modulated laser source along with a narrow band filtering at the detection drastically reduces the backscattering clutter, but does not affect the target return; the modulation frequency of the source is substantially above the cut-off frequency of the propagating medium. This technique allowed us to greatly improve underwater-target contrast. We associated with this frequency detection a temporal localization of the underwater target by using a pulse-modulated laser source.

In this paper, we present the evolution of speckle pattern polarimetric parameters in response to controlled changes in scatterer sizes, proportions, and the absorption coefficient in media. The experimental study was performed on mixtures of polystyrene microspheres with dye in order to ensure biological medium-like properties. The speckle grain sizes and degrees of polarization for linear and circular light were monitored. We observed helicity flipping in the degree of circular polarization for small scatterer proportion around 25%. Furthermore, linear depolarization decreased slightly for media containing more small particles. Good agreement was shown with numerical results computed using a Monte Carlo simulation of polarized light taking into account our experimental configuration. Speckle grain size also evolves with the increase of small scatterers as well as the media absorption coefficient. Such variations of properties are encountered during fruit maturation, in tissues in precancerous stages, and any transformation that causes a modification in particle proportions and absorption coefficient in biological media. The computed parameters proved to be sensitive to these changes.

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In this paper, we report a study in which a laser biospeckle technique is used to detect the climacteric peak indicating the optimal ripeness of fruits. We monitor two batches of harvested Golden apples going through the ripening phase in low- and room-temperature environments, determine speckle parameters, and measure the emitted ethylene concentration using gas chromatography as reference method. Speckle results are then correlated to the emitted ethylene concentration by a principal component analysis. From a practical point of view, this approach allows us to validate biospeckle as a noninvasive and alternative method to respiration rate and ethylene production for climacteric peak detection as a ripening index.

The noninvasive detection of a material's viscoelasticity is of great importance in the medical field. In fact, certain diseases cause changes in tissue structure and biological fluid viscosity; tracking those changes allows for detection of these diseases. Rheological measurements are also imperative in the industrial field, where it is necessary to characterize a material's viscoelasticity for manufacturing purposes. In this Letter, we present a noncontact, noninvasive, and low cost method for determining low viscosity values and variations in fluids. Laser speckle and viscometric measurements are performed on test samples having low scattering coefficients and low viscosities. The speckle spatial analysis proved to be as accurate as the speckle temporal correlation method reported in previous studies. Very low viscosities of the order of 1 mPa.s were retrieved for the first time using speckle images with either a frame rate of 1950 fps or a single acquired image.