Dynamic speckle laser (DLS) technique has been applied to the analysis of different biological systems, inorganic materials and industrial processes. In this paper, we use this technique to analyze the hygroscopic properties of different types of porcelain and papers for electrotechnical purposes. Experimental speckle results showed different behavior depending on physicochemical and textural properties of the samples.
When a lesion occurs in a blood vessel, a series of mechanisms are activated to stop hemorrhage by increasing blood
viscosity at the wounded place.
If a sample of blood extracted of the human body is illuminated with coherent light, a time varying speckle pattern is
observed. It is show high activity at the start and decreases with time until it finally stop.
The analysis of these patterns shows a degree of correlation between speckle activity and the temporal evolution of the
These preliminary results are promising for the continuation of studies aiming to the application of biospeckle techniques
to the analysis of coagulation times.
Biospeckle patterns are named also "boiling" speckles due to its dynamic appearance. This activity takes place when the
sample changes its properties due to diverse causes. This phenomenon is characteristic of biological samples and of the
some industrial process. There are many descriptors that have been developed to characterize biospeckle patterns. This
paper presents some approaches to compare and evaluate a set of time domain descriptors using a controlled experiment.
Chemotaxis has a meaningful role in several fields, such as microbial physiology, medicine and biotechnology. We present a new application of dynamic laser speckle (or biospeckle) to detect different degrees of bacterial motility during chemotactic response experiments. Encouraging results showed different bacterial dynamic responses due to differences in the hardness of the support in the swarming plates. We compare this method to a conventional technique that uses white light. Both methods showed to be analogous and, in some cases, complementary. The results suggest that biospeckle processed images can be used as an alternative method to evaluate bacterial chemotactic response and can supply additional information about the bacterial motility in different areas of the swarm plate assay that might be useful for biological analysis.
In this work we present to methods to evaluate activity in low dynamic speckle patterns. The first one is based on the
behavior analysis of the vortices associated to the pattern. The other one consists in binarizing the speckle image. The
speckle grain areas, also called islands, experiment displacements and deformations. The variations of the island features
were analyzed with the aim of finding a correlation with the activity of the speckle pattern. Both methods were evaluated
in numerical simulations and controlled experiments. From the obtained results, it was possible to conclude that the
developed methods can be very useful for the analysis of low activity speckle patterns with some advantages with other
Dynamic speckle is a useful technique to show biological tissue activity and evolving processes in industry. There are several algorithms for quantitative and qualitative characterization of dynamic speckle. We use the statistical method receiver operating characteristic (ROC) to compare some speckle algorithms. We estimate the capacity of these descriptors to discriminate different activities and the smallest number of images necessary for a correct description of the phenomena. We also use the ROC curves to estimate the best conditions required by some activities. The results are verified using an activity image.
Dynamic speckle techniques are useful tools for the study of temporal evolution. We use the difference histogram (DH) method for texture speckle image characterization. To test this proposal, two experiments were developed, concerning activity speckle images corresponding to live and dead seeds, and to drying of synthetic paints. The time history of the speckle pattern obtained from different stages of the samples was analyzed. The results are compared with those obtained from previous investigations performed with other methods. The comparison reveals that the proposed DH method is appropriate for this task.
Dynamic speckle images are useful tools to characterize the activity of biological tissues. In this paper, this technique was applied to determine chemotaxis responses of Pseudomonas aeruginosa towards attractants. Generalized weighted differences, wavelet entropy and spectral bands decomposition algorithms were used to characterize the speckle activity. Experimental results show regions with different bacterial activity. Dynamic speckle method exhibits a good performance for this application.
There are several algorithms for quantitative and qualitative characterization of dynamic speckle. In this paper, the statistical method named R.O.C (Receiver Operating Characteristic) is used to compare some speckle algorithms. We estimate the capacity of these descriptors in the discrimination of different activities.
Dynamic speckle or biospeckle is a phenomenon generated by laser light scattering in biological tissues. It is also present in some industrial processes where the surfaces exhibit some kind of activity. There are several methods to characterize the dynamic speckle pattern activity. For quantitative measurements, the Inertia Moment of the co occurrence matrix of the temporal history of the speckle pattern (THSP) is usually used.
In this work we propose the use of average dimensions (AD) for quantitative classifications of textures of THSP images corresponding to different stages of the sample.
The AD method was tested in an experiment with the drying of paint, a non biological phenomenon that we usually use as dynamic speckle initial test. We have chosen this phenomenon because its activity can be followed in a relatively simple way by gravimetric measures and because its behaviour is rather predictable. Also, the AD was applied to numerically simulated THSP images and the performance was compared with other quantitative method. Experiments with biological samples are currently under development.
When the speckle pattern produced by a scattering surface shows some type of activity, the speckle distribution changes in time. This paper presents a method to locally estimate the spatial variance of the temporal variation of the phase as an activity descriptor in a sequence of dynamic speckle. This method is based on the computation of the spatial autocorrelation of the speckle intensity using a sliding window. The image obtained from the resulting spatial variance matrix reveals areas of the sample with different speckle activity. Results obtained for both simulated and experimental data are also shown.
Dynamic speckle or biospeckle is observed in biological samples illuminated by laser light. The properties and applications of this phenomenon have been treated in the literature. In this paper, we present a method of dynamic speckle analysis based on the filtering in frequency bands of the temporary history of each pixel. Butterworth filters are applied to the temporary evolution and different images are constructed showing the energy in each frequency band. Applications on vegetable specimens examples are shown.
Algorithms used to process a speckle image are limited by the resolution of the CCD camera and the employed digitalization system. We propose the use of dithering procedures to increase the intensity discrimination and improve the contrast resolution. This technique consists in decreasing the quantification error by performing several measurements to which a random value is added in each measurement before detection. Hence, it is possible to find a more approximated value to the real one. The precision increase results from the use of multiple images to which a determined white-light intensity has been added. This work shows the results of applying dithering to improve the precision of methods that use speckle contrast. It is a frequently used quantity in the implementation of activity images and in the determination of surface roughness. Numerically simulated images were used to verify the reliability of the technique whose intensities were later quantified for processing. The observed mean squared error is lower when this technique is employed, and the level of improvement depends on the size of the used windows. A device for the experimental verification of the results is in the design stage.
When an optically rough surface illuminated by a laser evolves in time the scattered light gives rise to a dynamic speckle pattern and its variation depends on the activity of the sample. Biological samples show this behavior but it also can be observed is some other dynamic processes such as drying of paint, corrosion, heat exchange, blood flow, vibrations, etc. In this work we present a dynamic speckle phenomenon that occurs in the development of foams. The experimental results show the time evolution of the samples and offer a potential applicability of this measurement technique to the assessment of this type of processes.
The dynamic speckle is a phenomenon generated by laser light scattering in biological tissues and it is also present in some industrial processes where the surfaces exhibit some kind of activity. In this work we present preliminary results of a numerical model to describe the time history of a dynamic speckle pattern considering very simplified situations.
The dynamic speckle is a phenomenon generated by laser light scattering in biological tissues and it is also present in some industrial processes where the surfaces exhibit some kind of activity. In our case, the process of drying of paint has been studied and its activity is explored using dynamic speckle techniques. Two alternative speckle contrast methods are presented to characterize faster processes.
The dynamic speckle, also known as biospeckle or bioactivity is a phenomenon generated by laser light scattering in biological tissues or in surfaces exhibiting some kind of activity. In our case, seeds tissue has been employed and its activity studied and explored. In this research work we suggest a bio-speckle technique as a potential methodology to analyze seeds viability.
A cheap piezoelectrically driven mirror can be easily constructed in the laboratory. It can be located in one arm of a DSPI interferometer in order to introduce a controlled phase step. A procedure to calibrate this device is shown, that is based on the evaluation of the fringes obtained with the interferometer. To evaluate the performance of the calibrated device, the phase map of a simulated plane object is calculated, using the four-step algorithm for the images of a speckle interferogram.
When a rough surface changes, its optical properties change also and the scattered light shows intensity fluctuations named dynamic speckle. Fruits, even hard peel ones, shows a speckle activity that can be related to maturity, turgor, damage, aging, and mechanical properties. Many techniques have been sued to study these properties, most of them destructive ones. We present an application of dynamical speckle to the study of impact on apples and the analysis of bruises produced by them. The aim is to correlate physical properties of apples with quality factors.
This work shows a new technique as a potential methodology to analysis seed. The technology is the dynamic speckle, phenomena produced by the laser illumination on a biological tissue, in this case the seed tissues. In order to develop this technique, it was necessary to know exactly the effect of the water content in the seed on the results, that was evaluated in this research, by the evaluation of the Inertia Moment of seeds in five levels of moisture (13, 20, 30, 37 and 46%). One of the treatments was the use of pvc film to eliminate the evaporation effect. It was analyzed 450 seeds in five degrees of moisture, with and without film, at three consecutive times, and also in a three times replication. Another experiment was the comparison of dead and alive seeds activity by the Inertia Moment in time. The results showed that the moisture influence the level of activity measured by the Inertia Moment technique, that is an important condition to be controlled on the future experiments, and that it is possible to separate dead to alive seeds by Inertia Moment.
We present a display showing dynamic speckle local activity as that observe when coherent light illuminates biological samples (biospeckle). Regions differing in their activity are shown as different gray levels. Results obtained with seeds and drying of paint are shown. We propose its use in the determination of seeds viability, detection of corrosion centers and local variations in surface roughness.
The drying of paints was followed using the time evolution of the activity of dynamic speckle patterns. For processing the data an alternative method based in the use of the second order moment of the modified co-occurrence matrix of the time history of its intensity was used. The experimental results obtained were compared with gravimetrical techniques. The results are discussed on the basis of the knowledge of the coating drying process.
The full width at half maximum (FWHM) is sometimes used to characterize the autocorrelation function of the time history of a speckle pattern. We propose to include more autocorrelation points to diminish the variability of the measurement. The width of the equivalent rectangle (WER) and the X*LOG X measurements are defined and some simulations and experimental results obtained are shown.