We present an alternative approach for using dynamic laser speckle data to quantify biophysical dynamics including ordered flows and random motions. The approach yields images that superficially resemble traditional laser speckle contrast images, but instead of relying on the statistics of the local time integrated intensity values calculated over temporal and sliding spatial windows as is done in LSCI to create images, ellipticity imaging (EI) directly yields images that quantify the relative dominance of long-range correlations in the temporal dimension of a series of speckle patterns to the short-range correlations in the same dimension. The approach relies on a Poincaré analysis of the speckle data which yields metrics that statistically describe both the short-terms variations in the temporal speckle intensity (i.e., the standard deviation in successive differences) and also the corresponding long term variations. These metrics are plotted against each other (Poincaré plots) and an ellipse fit to the data. The ratio of the semi-major axis to the semi-minor axis of this ellipse for each temporal speckle sequence is then used as the data to form the images (thus the term EI). The results of flow phantom and mouse EI studies will be presented. Various flow rates of dilute intralipid were illuminated with a coherent laser source and EI images were generated. The same speckle data were analyzed using spatial and temporal LSCI approaches. Flows in anesthetized mouse brain vessels were analyzed using EI and LSCI approaches. The results of the studies using the different speckle analyses will be discussed.
In vivo optical trapping is a novel applied direction of an optical manipulation, which enables one to noninvasive measurement of mechanical properties of cells and tissues in living animals directly. But an application area of this direction is limited because strong scattering of many biological tissues. An optical clearing enables one to decrease the scattering and therefore increase a depth of light penetration, decrease a distortion of light beam, improve a resolution in imaging applications. Now novel methods had appeared for a measurement an optical clearing degree at a cellular level. But these methods aren’t applicable in vivo. In this paper we present novel measurement method of estimate of the optical clearing, which are based on a measurement of optical trap stiffness. Our method may be applicable in vivo.
In this paper, we present a novel simple technique of Fourier-transform holographic microscopy (FTHM). Simplicity of the scheme, possibility to use a small image sensor and provide compensation of aberration, enable one to construct inexpensive holographic microscopes. We experimentally compare FTHM with in-line holographic microscopy. In this paper, we present experimental scheme of FTHM, description of used algorithms and experimental results for an amplitude test object and biological samples (blood smears).
We present a novel technique for 3D-tracking micro- and nanoparticles with original lens-free dark-field holographic microscope. Combining lens-free and dark-field microscopy principles this technique allows for high accuracy localization of micro- and nanoparticles using single hologram acquired with compact setup built with minimal use of optical components. In this paper, we present technique of particles localization, experimental setup, technique of digital correction of spherical aberration, results of simulation and experimental data.