In: Physical Review E, 2006, vol. 73(1), p. 011413
We present a detection scheme for diffusing-wave spectroscopy (DWS) based on a two-cell geometry that allows efficient ensemble averaging. This is achieved by putting a fast rotating diffuser in the optical path between laser and sample. We show that the recorded (multispeckle) correlation echoes provide an ensemble averaged signal that does not require additional time averaging. Furthermore,...
|
In: Applied Optics, 2006, vol. 45, no. 8, p. 1756-1764
We introduce a charge-coupled device (CCD) camera-based detection scheme in dynamic light scattering that provides information on the single-scattered autocorrelation function even for fairly turbid samples. It is based on the single focused laser beam geometry combined with the selective cross-correlation analysis of the scattered light intensity. Using a CCD camera as a multispeckle...
|
In: Optical Imaging of Neocortical Dynamics, 2014, vol. 85, p. 255–271
Optical imaging of cerebral hemodynamics has been used extensively to investigate the complex interplay between neurons and the blood-borne supply of oxygen and energy substrates. Among several techniques, the so-called laser speckle imaging (LSI) has found widespread applications for studying (patho-)physiological aspects of neurovascular coupling. LSI is a rather simple and cost-effective...
|
In: Optics Letters, 2006, vol. 31, no. 23, p. 3465-3467
We have analyzed the image formation and dynamic properties in laser speckle imaging (LSI) both experimentally and with Monte Carlo simulation. We show for the case of a liquid inclusion that the spatial resolution and the signal itself are both significantly affected by scattering from the turbid environment. Multiple scattering leads to blurring of the dynamic inhomogeneity as detected by...
|
In: Proceedings SPIE, 2015, vol. 9540, p. 954008–954008–9
We present an improved Laser speckle imaging approach to investigate the cerebral blood flow response following function stimulation of a single vibrissa. By synchronising speckle analysis with the cardiac cycle we are able to obtain robust averaging of the correlation signals while at the same time removing the contributions due to the pulsation of blood flow and associated tissue adaptation....
|
In: Optics Express, 2009, vol. 17, no. 16, p. 13904-13917
Laser speckle imaging (LSI) based on the speckle contrast analysis is a simple and robust technique for imaging of heterogeneous dynamics. LSI finds frequent application for dynamical mapping of cerebral blood flow, as it features high spatial and temporal resolution. However, the quantitative interpretation of the acquired data is not straightforward for the common case of a speckle field formed...
|
In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 43–46
We investigate the structure and the dynamics of dense suspensions of NIH 3T3 fibroblast cells. Using two-photon microscopy we obtain three dimensional (3D) images from which the size and the packing structure of the dense cell suspensions can be extracted. In addition, we analyse the global time-dependent behaviour of the suspensions by time-lapse measurements of cell sedimentation. Since...
|
In: Journal of Statistical Mechanics: Theory and Experiment, 2016, vol. 2016, no. 9, p. 094003
We investigate structural and dynamical properties of moderately polydisperse emulsions across an extended range of droplet volume fractions phgr, encompassing fluid and glassy states up to jamming. Combining experiments and simulations, we show that when phgr approaches the glass transition volume fraction ${{\phi}_{g}}$ , dynamical heterogeneities and amorphous order arise within the...
|
In: Korea-Australia Rheology Journal, 2017, vol. 29, no. 4, p. 241–247
Diffusing wave spectroscopy (DWS) can be employed as an optical rheology tool with numerous applications for studying the structure, dynamics and linear viscoelastic properties of complex fluids, foams, glasses and gels. To carry out DWS measurements, one first needs to quantify the static optical properties of the sample under investigation, i.e. the transport mean free path l* and the...
|
In: Physical Review E, 2015, vol. 91, no. 3, p. 032302
We model the packing structure of a marginally jammed bulk ensemble of polydisperse spheres. To this end we expand on the granocentric model [Clusel et al., Nature (London) 460, 611 (2009)], explicitly taking into account rattlers. This leads to a relationship between the characteristic parameters of the packing, such as the mean number of neighbors and the fraction of rattlers, and the radial...
|
