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Abstract: Integration of color information in 3D models acquired with a topometric measurement system opens a wide field of applications in medicine, e.g. prosthetics. To ensure an accurate and reliable color reproduction in a 3D topometric measurement system, different approaches have been evaluated. These techniques focus on the calibration of the CCD camera using color test charts by applying a polynomial regression method as well as numerical methods to compensate an intensity decay of the illumination in 3D datasets which is caused by varying distances and orientations of the measured object with respect to the light source. The methods presented in this contribution have been applied to a topometric measurement system with one-chip color CCD cameras. An enhanced color reproduction of various objects is demonstrated. [Copyright &y& Elsevier]

Abstract: Partial coherent light sources open up prospects for phase noise reduction in digital holographically reconstructed phase distributions by suppressing multiple reflections in the experimental setup. Thus, light emitting diodes (LEDs) are investigated for application in digital holographic microscopy. First, the spectral properties and the resulting coherence length of an LED are characterised. In addition, an analysis of dispersion effects and their influence on the hologram formation is carried out. The coherence length of LEDs in the range of a few micrometers restricts the maximum interference fringe number in off-axis holography for spatial phase shifting. Thus, the application of temporal phase-shifting-based digital holographic reconstruction techniques is compared to spatial phase-shifting-based methods. It is demonstrated that LEDs are applicable for digital holographic microscopy in connection with both spatial and temporal phase-shifting-based techniques for reduction of noise in comparison to a laser-light-based experimental setup. [Copyright &y& Elsevier]

Abstract: A variety of physical and biochemical cell properties depends on the function and integrity of the actin cytoskeleton. The actin cytoskeleton mediates crucial cellular functions as migration, intracellular transport, exocytosis, endocytosis, cell stiffness and force generation. Highly dynamic actin fibers are therefore targets for several drugs and toxins. However, the study of actin interfering processes by standard microscopy techniques fails in the detailed resolution of dynamic spatial alterations required for a deeper understanding of toxic or drug effects. Here we applied digital holographic microscopy in the online functional analysis of the actin cytoskeleton changes of a highly differentiated and a dedifferentiated pancreas tumor cell line induced by the marine toxin Latrunculin B. Scanning electron microscopy (SEM) and fluorescence microscopy showed rapid Latrunculin B induced alterations in cell morphology and actin fiber degradation in both pancreatic tumor cell lines. In contrast digital holographic in vivo analysis of the drug dependent dynamic cellular processes revealed unequal changes in cell morphology. While tumor cells with a low metastatic potential showed Latrunculin B induced cell collapse within 4h the metastatic tumor cells were resistant to Latrunculin B treatment. Spatial resolution of morphological alterations by digital holography detected so far unknown differences in the actin cytoskeleton stability of highly differentiated and dedifferentiated pancreas tumor cell lines. These data demonstrate that marker-free, non-destructive online analysis of cellular morphology and dynamic spatial processes in living cells by digital holography offers new insights in actin dependent cellular mechanisms. Digital holographic microscopy was shown to be a versatile tool in the screening of toxic drug effects and cancer cell biology. [Copyright &y& Elsevier]

Abstract: In electronic speckle pattern interferometry (ESPI), for a fast and objective analysis of measurement data which occur with a high repetition rate, an automated data processing is of particular advantage. For this reason, investigations were carried out to determine if the modulation of speckle interferograms can be applied as a quality parameter for the selection of suitable interferogram data for further evaluation e.g. phase unwrapping when spatial phase shifting (SPS) is performed. Six methods for determining the modulation of speckle interferograms are characterised and compared. The applicability of the speckle interferogram modulation as a parameter for mask generation in the unwrapping process of the phase difference is demonstrated by the evaluation of measurement data obtained from experiments with a spatial phase shifting endoscopic ESPI system on a technical surface and on a human gastrectomy specimen. [Copyright &y& Elsevier]

Abstract: Electronic speckle pattern interferometry (ESPI) is a well-established tool for non-destructive testing. It allows the quantitative determination of surface deformations and micro-movements with a sub-micrometer resolution. In the case of objects which are extended in depth, however, the evaluation and interpretation of the resulting correlation fringe patterns can be affected by perspective image distortions as well as by a varying image size. In this paper a method for combination of ESPI with a photogrammetric 3D coordinate measurement is presented. In this way, interferogram data are precisely allocated in 3D-space. Furthermore, it is possible to take into account a spatially varying sensitivity vector. The utilizability of the method is demonstrated by a deformation measurement on a stone sculpture. [Copyright &y& Elsevier]