Measurements of average phase shifts introduced by living HeLa cells to probe wave front were carried out. Variations of this value were monitored in the course of morphological changes caused by photodynamic treatment at various irradiation doses. Observations of changes in living cells were also performed by means of far field optical microscopy and confocal fluorescent microscopy. Quantitative analysis of the data obtained shows that average phase shift introduced by the cells may either increase or decrease depending upon major parameters of the treatment.
We demonstrate an alternative approach to determination of the third order elastic moduli of materials based on
registration of nonlinear bulk strain waves in three basic structural waveguides (rod, plate and shell) and further
calculation of the Murnaghan moduli from the recorded wave parameters via simple algebra. These elastic moduli are
available in literature for a limited number of materials and are measured with considerable errors, that evidences a
demand in novel approaches to their determination.
The paper presents results on singlet oxygen detection in aqueous solutions of a photosensitizer based on the reconstruction of 3D temperature gradients resulting from nonradiative deactivation of excited oxygen molecules. 3D temperature distributions were reconstructed by means of the inverse Abel transformation from a single digital hologram in the case of cylindrically symmetric distribution of the temperature gradient and using holographic tomography algorithm with filtered back projection in the case of nonsymmetrical distribution. Major features of the applied techniques are discussed and results obtained by the two methods are compared.
Digital holography is widely used nowadays for interferometric studies of various objects and processes. However, peculiarities of objects under study often imply difficulties in holograms recording, reconstruction and processing. One of the major factors is a typically large number of singular points at phase distributions caused by either low signal to noise ratio at the recorded holograms or sample inhomogeneities. The basic operations applied for absolute phase extracting from digital holograms are noise filtration, phase unwrapping and subtraction of phase distributions. In this paper we demonstrate that the sequence of these operations may drastically affect the resulting image quality and the data obtained. An optimized algorithm suitable for studies of dynamic processes in biological media on microscopic level has been developed. The algorithm was applied for monitoring of nonradiative deactivation processes occurring in onion cell specimens at photosensitized generation of singlet oxygen.
Modern structural elements are often made of laminated polymer materials or composites on the base of polymer matrices. The proper functioning of these elements may be of vital importance especially in automotive and aerospace industries, in gas and oil transportation. The major problem in their performance is a possibility of a sudden and irreversible delamination caused by various factors. We propose and study a NDT approach aimed to detect delamination areas in adhesively bonded layered structural elements made of different materials. The proposed approach is evaluated by use of holographic detection and monitoring of the evolution of bulk strain solitons generated in such structures.
The paper presents a novel combined approach aimed to detect and monitor singlet oxygen molecules in biological specimens by means of the simultaneous recording and monitoring of their deactivation dynamics in the two complementary channels: radiative and nonradiative. The approach involves both the direct registration of phosphorescence at the wavelength of about 1270 nm caused by radiative relaxation of excited singlet oxygen molecules and holographic recording of thermal disturbances in the medium produced by their nonradiative relaxation. The data provides a complete set of information on singlet oxygen location and dynamics in the medium. The approach was validated in the case study of photosensitized generation of singlet oxygen in onion cell structures.