Papers by Keyword: Spatial Resolution

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Authors: Le Chen, Xiao Li Zhang, Yan Song
Abstract: Based on the principle of the distributed optical fiber temperature sensor, the research with temperature calibration technique for temperature measurement precision of system was studied in this paper. Accurate temperature was gotten by standards of environmental temperature thermometer, with different temperature calibration methods to solve the accuracy problem of the distributed optical fiber temperature sensor.
Authors: Xin Min Shen, Mikinori Nagano, Wen Qiang Peng, Yi Fan Dai, Kazuya Yamamura
Abstract: Local wet etching (LWE) is a non-conventional deterministic surface figuring and finishing technique in ultra-precision optics fabrication fields. The general removal function in LWE is cylinder, so fringe of the removal function is sharp and scale of the removal function is determined by inner diameter of the nozzle head. When fabricating some specimen with high frequency figure error, ideal designed shape can’t be achieved easily. Compared with general LWE removal function, Gaussian removal function is more suitable for figuring owing to its smoother fringe and the centralization of its energy. At the same time Gaussian removal function can improve the efficiency in calculation of the dwelling time, because it’s very suitable for Fourier transform. What’s more, theoretical residual figure error can also be reduced for Gaussian removal function’s high spatial resolution. Ideal Gaussian function is difficult to obtain in LWE, so we have proposed near-Gaussian removal function by eccentric rotation of the nozzle head. Through controlling offset of the eccentric rotation, we achieve the optimal near-Gaussian removal function in LWE. Aims of the introduction of near-Gaussian removal function in LWE are to improve the fabrication efficiency and to remove the surface’s high frequency residual figure error.
Authors: X. Zhou, Jun Gong, Y. Liu, J. Zhou
Authors: Zi Qi Ma, Xue Song Liu, Yi Cheng, Liang Zhang, Jian Gang Shi, Hong Yuan Fang, Shi Long Wang
Abstract: Analysis the shortage of ultrasonic stress measurement based on Lcr wave in low spatial resolution. Point out it is inapplicable in measuring gradient stress field like welding residual stress field. In this paper, propagation differential method is proposed to solve the low spatial resolution problem on Lcr wave stress measurement, and its theory is introduced. This method can raise the spatial resolution from tens of millimeter to a several millimeter level with out decline the stress resolution. A welding residual stress field of 7N01 aluminum alloy butted joint plate is measured by this method, and its result is compared with hole drilling method. Source of errors is discussed. It is seen that propagation differential method is applicable in welding residual stress measurement.
Authors: Sergei Stuchebrov, Dan Verigin, Yelena Lukyanenko, Maria Siniagina, Alexander Wagner
Abstract: In the work digital x-ray apparatus on the basis of the gas-discharge linear detector is considered. X-ray images of laboratory rats are presented. Application prospects of gas-discharge detectors as a solution of the up-to-date radiographic problems are deduced.
Authors: Masaaki Futamoto, Tatsuya Hagami, Shinji Ishihara, Kazuki Soneta, Mitsuru Ohtake
Abstract: Effects of magnetic material, coating thickness, and tip radius on magnetic force microscope (MFM) spatial resolution have been systematically investigated. MFM tips are prepared by using an UHV sputtering system by coating magnetic materials on non-magnetic Si tips employing targets of Ni, Ni-Fe, Co, Fe, Fe-B, and Fe-Pd. MFM spatial resolutions better than 9 nm have been confirmed by employing magnetic tips coated with high magnetic moment materials with optimized thicknesses.
Authors: Ryo Suzuki, Shinji Ishihara, Mitsuru Ohtake, Masaaki Futamoto
Abstract: Magnetic force microscope (MFM) tips are prepared by coating Si tips of 4 nm radius with [Co (1 nm)/M(1 nm)]20 (M = Pt, Pd, Ni) multilayer films. An MFM tip prepared by coating 40-nm-thick Co film is employed as a reference tip. The influences of M layer material on the spatial resolution and the switching field of MFM tip are investigated. The spatial resolutions of Co/M multilayer coated tips are estimated to be within 9.4 ± 0.3 nm for all the M materials, which is about 6% inferior to that of Co coated tip (8.8 nm). Higher switching fields of 1425 and 825 Oe are respectively observed for the tips coated with Co/Pt and Co/Pd multilayers, whereas the field of tip coated with Co/Ni multilayer is 275 Oe which is similar to that of Co coated tip (325 Oe). The switching field is influenced by the magnetic anisotropy of multilayer film. An MFM tip coated with Co/Pt multilayer film is useful to observe the magnetic domain structure of permanent magnets and magnetic recording media.
Authors: Ting Ting Li
Abstract: With the rapid development of DOA (direction-of-arrival) estimation methods, the existing beamforming technologies still have the problem of a way to balance high spatial resolution and robust performance. The aperture extension characteristics of fourth-order cumulants is used to raise the spatial resolution of the array in this paper. By using the structure of minimum redundancy array, the calculation of the fourth-order cumulants matrix can be reduced. Simulations of the properties of fourth–order cumulants beamforming method are analyzed in this paper, including the resolution analysis, multi-sources analysis and error analysis. Simulation results show that the fourth-order cumulants beamforming method has a higher spatial resolution than the conventional beamforming method without increasing the number of the array sensors.
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