813 research outputs found

    Three-dimensional particle tracking via tunable color-encoded multiplexing.

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    We present a novel 3D tracking approach capable of locating single particles with nanometric precision over wide axial ranges. Our method uses a fast acousto-optic liquid lens implemented in a bright field microscope to multiplex light based on color into different and selectable focal planes. By separating the red, green, and blue channels from an image captured with a color camera, information from up to three focal planes can be retrieved. Multiplane information from the particle diffraction rings enables precisely locating and tracking individual objects up to an axial range about 5 times larger than conventional single-plane approaches. We apply our method to the 3D visualization of the well-known coffee-stain phenomenon in evaporating water droplets

    Variable optical elements for fast focus control

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    In this Review, we survey recent developments in the emerging field of high-speed variable-z-focus optical elements, which are driving important innovations in advanced imaging and materials processing applications. Three-dimensional biomedical imaging, high-throughput industrial inspection, advanced spectroscopies, and other optical characterization and materials modification methods have made great strides forward in recent years due to precise and rapid axial control of light. Three state-of-the-art key optical technologies that enable fast z-focus modulation are reviewed, along with a discussion of the implications of the new developments in variable optical elements and their impact on technologically relevant applications

    Parameter-Free Test of Alloy Dendrite Growth Theory

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    In rapid alloy solidification the dendrite-growth velocity depends sensitively on the deviations from local interfacial equilibrium manifested by kinetic effects such as solute trapping. The dendrite tip velocity undercooling function was measured in dilute Ni~Zr! over the range 1–25 m/s and 50–255 K using electromagnetic levitation techniques and compared to theoretical predictions of the model of Trivedi and colleagues for dendritic growth with deviations from local interfacial equilibrium. The input parameter to which the model predictions are most sensitive, the diffusive speed VD characterizing solute trapping, was not used as a free parameter but was measured independently by pulsed laser melting techniques, as was another input parameter, the liquid diffusivity DL. Best-fit values from the pulsed laser melting experiment are VD526 m/s and DL 52.731029 m2/s. Inserting these values into the dendrite growth model results in excellent agreement with experiment with no adjustable parameters.Engineering and Applied Science

    The Interface between Intellectual Property Law and Competition Law in the North American Context

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    intellectual property and competition law in North Americ

    The Interface between Intellectual Property Law and Competition Law in the North American Context

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    intellectual property and competition law in North Americ
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