We present a type of diffractive lens, Zernike apodized photon sieves (ZAPS), used as the objective for high spatial resolution and high phase-contrast imaging of weakly absorbing materials in x rays. The structure of ZAPS is based on the combination of two concepts: apodized photon sieves and Zernike phase contrast. The ZAPS is a single optic that integrates the appropriate ±π/2 rad phase shift through selective zone placement shifts in an apodized photon sieve. Analysis of the focusing properties of the apodized photon sieve in terms of point-spread function show that the sidelobes have been significantly suppressed at the expense of slightly widening the width of the main lobe. In combination with synchrotron light sources, ZAPS offers new opportunities for high-resolution phase-contrast x-ray microscopy in the physical and life sciences.
The unscented Kalman filter (UKF) is presented as an alternative of extend Kalman filter (EKF) for bearing-only tracking. Compared with EKF, UKF has a better performance that estimation precision does not depend on state initialization error. In the same noise angle measurement data, UKF has better precision. UKF can be used to have a good estimation at large state initialization error. Simulation experiments are present and show that UKF is used for better state estimation result in 3-dimensin bearing-only tracking.
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