Papers by Author: Xiao Tang Hu

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Authors: Mao Sen Bai, Xing Fu, Dante Dorantes, Bao Yin Jin, Xiao Tang Hu
Abstract: A novel faint signal processing method based on phase-lock amplification principle is developed to enhance the sensitivity of pump/probe-based laser generated and laser detected surface acoustic waves (LG/LD SAW) spectroscopy system. This novel method involves a “dead zone” filter located before a common phase-lock amplification unit, which wipes off most of the noise stacked on SAW signal. This paper explored the working principle of this novel signal processing method based on the knowledge of the characteristics of the system noise and the signal. The experiment result shows that the detection system’s sensitivity has been dramatically improved by this new signal processing method.
Authors: Ying Cheng, Feng Zhou Fang, Xiao Dong Zhang, Xiao Tang Hu
Abstract: The solar concentrator is the primary means of solving the contradiction between cost and photoelectric conversion efficiency. The design and fabrication of concentrator are the key techniques to accelerate the application of photovoltaic systems. A novel type of composite concentrator is designed, including two mirrors and one planar lens. The primary mirror focuses the sunlight on the secondary condenser, which is one multi-segmented cone mirror to produce homogenization on the solar cell. The selection strategy of structure parameters is analyzed by the numerical calculation methods. The concentration ratio and homogenization on the receiving surface are also obtained using the optical simulation method. The designed mirrors are fabricated by the ultra-precision turning method, and then assembled according to the location parameters designed. The proposed methods are proved to be satisfied with the solar application efficiently by the experiments.
Authors: N. Geng, Xing Fu, H.X. Li, X.C. Ni, Xiao Tang Hu
Abstract: A 775nm femtosecond laser is applied to single crystal silicon by direct-write processing in air. A series of holes are drilled with 150fs duration pulses, various numbers of laser pulses and laser fluences on silicon wafer. Different laser parameters and material properties influence the size of fabricated holes. The diameter and depth of holes are gradually enlarged with the increase of laser fluence and pulse number. The periodic ripple structure on silicon surface is found and explained at the same time.
Authors: Zong Wei Xu, Feng Zhou Fang, Xiao Tang Hu
Abstract: Carbon nanotube (CNT) probe used in atomic force microscopy (AFM) was fabricated by using electron beam induced Pt deposition method. The bonding force for CNT probe was found to be larger than 500nN. The nanotube probe’s length was shortened by focused ion beam milling process. It is confirmed that the CNT probe shows higher aspect ratio than the Si probe. The nanotube probes with fullerene-like cap end present higher imaging resolution than those with open end.
Authors: Feng Zhou Fang, Yu Chan Liu, Qing Xiang Pei, Xiao Tang Hu
Abstract: A new method on examining the micro cracks of monocrystalline silicon during nano indentation is proposed. It is established based on a study of the increasing rate of absorbed energy in nano indentation. This method provides a simple approach in understanding whether cracks on the silicon surfaces occur, while it is tedious in conventional method.
Authors: Chun Yang Liu, Xing Fu, Yong Wu, Feng Ming Sun, Xiao Tang Hu
Abstract: We study some microstructures fabricated by designed 355nm ultraviolet nanosecond pulse laser micromachining system, which consists of LASER, mechanical and optical structure, 3D work platform, and control system. Nanosecond pulse LASER, with 40ns pulse duration, is chosen as the light source. Mechanical and optical structure is designed for laser beam focusing. Computer software resolves the graphics. And control system based on DSP and FPGA is designed to drive the 3D work platform. Raster sensor is used to measure the real distance that the platform moves. Using this system, some experiments are analyzed and some parameters are optimized. Some microstructures are also fabricated on single crystal silicon wafer and organic glass. The lines of fabricated graphics are 20-40um wide and smooth, with less effect of heat.
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