The evaluation of the characteristics of a dental restorative material is based on several criteria such as the
ability of the material to resist to potential degradation, its durability, the stress it exerts on the residual dental structures,
its resistance to surface wear, and its resistance to fracture. All these important factors must be taken into account and
tested when developing a new dental restorative material. Glass ionomer cements (GIC) possess unique properties,
including adhesion to tooth structure, bioactivity and fluoride release. The objective of this study is to evaluate by
analyzing the dynamics of the polarized speckle field how GIC samples, prepared according to two different methods
and conserved in water at 35°C, deteriorate.
Glass-ionomer cements (GIC) belong to the class of materials known as acid-base cements. The drying process of these materials and the evolution of their physical properties play an important role in the quality and durability of dental care. Since monitoring these processes contributes to the improvement of the knowledge on these materials, we aim in our work to monitor in real-time hardening of GIC using dynamic speckle. Speckle images are temporally analyzed by computing the temporal correlation coefficient. The temporal correlation curves present a Lorentzian profile, which characteristics vary during GIC hardening process.
This paper presents an application of laser speckle imaging method to characterize the kinetic growth of Bacillus thuringiensis (Bt). Numbers of parameters, such as speckle grain size and spatial contrast, are considered in order to characterize the culture medium and to monitor in real time the fermentation process. We show that the grain size and the contrast of the speckle image decrease with the increase of the cells concentration. The correlation of speckle results with optical density measurements shows the effectiveness of dynamic speckle for real-time monitoring of Bt cells growth kinetics.
Dental erosion starts with a chemical attack on dental tissue causing tooth demineralization, altering the tooth structure and making it more sensitive to mechanical erosion. Medical diagnosis of dental erosion is commonly achieved through a visual inspection by the dentist during dental checkups and is therefore highly dependent on the operator’s experience. The detection of this disease at preliminary stages is important since, once the damage is done, cares become more complicated. We investigate the difference in light-scattering properties between healthy and eroded teeth. A change in light-scattering properties is observed and a transition from volume to surface backscattering is detected by means of polarized laser speckle imaging as teeth undergo acid etching, suggesting an increase in enamel surface roughness.
Physical and mechanical properties of cork allow it solving many types of problems and make it suitable for a wide range of applications. Our objective consists into studying cork’s water absorption by analyzing the dynamic speckle field using the temporal correlation method. Experimental results show that the medium was inert at first with the absence of activity, and as the cap cork was more and more immersed into water, the presence of the activity becomes more significant. This temporal parameter revealed the sensibility of biospeckle method to monitor the amount of absorbed water by cork caps.
Changes in scatterers dimensions, size proportions, scattering coefficients, refractive index etc. can be detected and quantified using laser speckle analysis. In this study, we consider samples designed for this study with controlled scatterers sizes and proportions. A good agreement between experimental results performed on media with controlled parameters, fruits undergoing maturation, and Monte Carlo simulations is demonstrated.
Our study is based on using a non-invasive technique, the bio-speckle technique, in order to follow the ripening
of fruits during different stages: before and after the climacteric stage. To assess the impact of the ripening
of fruits on their optical properties, speckle grain is measured and the variation of its dimensions is evaluated.
In addition, and in order to correlate this observation with the degradation of chlorophylls, both a physical
approach based on recording the fluorescence spectrum of chlorophylls, and a biochemical approach based on a
pigmentation analysis, are used. We therefore show the efficiency of biospeckle metrology for monitoring fruit
maturation.
The 3D structure of light scattering from dark-field illuminated live 3T3 cells marked with 40 nm gold nanomarkers
is explored. For this purpose, we use a high resolution holographic microscope combining the off-axis heterodyne
geometry and the phase-shifting acquisition of the digital holograms. Images are obtained using a novel
3D reconstruction method providing longitudinally undistorted 3D images. A comparative study of the 3D reconstructions
of the scattered fields allows us to locate the gold markers which yield, contrarily to the cellular
structures, well defined bright scattering patterns that are not angularly titled and clearly located along the optical
axis. This characterization is an unambiguous signature of the presence of the gold biological nanomarkers,
and validates the capability of digital holographic microscopy to discriminate them from background signals in
live cells.
In this communication, we show that off-axis digital holography combined to phase-shifting acquisition of holograms
is an effective microscopic tool to fully localize, in three dimensions, transmembrane receptors of living
cells tagged with Gold nanocolloids. Gold nanoparticles, known for their interesting optical properties as well as
for their noncytotoxicity are used here as biomarkers to target the cellular receptors.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.