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Qiu W.C.,National University of Defense Technology | Cheng X.A.,National University of Defense Technology | Cheng X.A.,Science and Technology on Electro Optical Information Security Control Laboratory | Wang R.,National University of Defense Technology | And 2 more authors.
Journal of Applied Physics | Year: 2014

In this paper, experimental results of temperature-dependent signal inversion of laser beam induced current (LBIC) for femtosecond-laser-drilling- induced junction on vacancy-doped p-type HgCdTe are reported. LBIC characterization shows that the traps induced by femtosecond laser drilling are sensitive to temperature. Theoretical models for trap-related p-n junction transformation are proposed and demonstrated using numerical simulations. The simulations are in good agreement with the experimental results. The effects of traps and mixed conduction are possibly the main reasons that result in the novel signal inversion of LBIC microscope at room temperature. The research results provide a theoretical guide for practical applications of large-scale array HgCdTe infrared photovoltaic detectors formed by femtosecond laser drilling, which may act as a potential new method for fabricating HgCdTe photodiodes. © 2014 AIP Publishing LLC.

Jin S.,Shaanxi University of Technology | Tan W.,Shaanxi University of Technology | Liu X.,Science and Technology on Electro Optical Information Security Control Laboratory | Wu B.,Shaanxi University of Technology | Si J.,Shaanxi University of Technology
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

The Monte Carlo method is introduced to simulate and analyze the influence of optical parameters of the turbid medium, such as anisotropy factor, on the temporal and spatial distributions and scattering-order distributions of ultrashort pulses. The result shows that when anisotropy factor or absorption coefficient decrease and scattering coefficient or propagation depth increase, both of the pulse duration and the beam size broaden and the proportion of scattering photons at high scattering orders increase.

Ren G.,Xiangtan University | Ren G.,Science and Technology on Electro Optical Information Security Control Laboratory | Zeng S.,Xiangtan University | Zeng S.,Hong Kong Polytechnic University | Hao J.,Hong Kong Polytechnic University
Journal of Physical Chemistry C | Year: 2011

In this paper, highly monodispsered ultrasmall hexagonal phase NaGdF 4 nanorods were synthesized via a hydrothermal method using oleic acid as a stabilizing agent. The tunable multicolor upconversion (UC) emissions, including green, yellow, blue, and white emissions, can be readily achieved from lanthanide (Ln)-doped NaGdF 4 nanorods under the excitation of a 980 nm diode laser. The calculated chromaticity coordinates (CIE-X = 0.346, CIE-Y = 0.357) are close to those of the standard white light (CIE-X = 0.33, CIE-Y = 0.33), and the white UC emissions can be tuned from blue-white to white by adjusting the doped contents of Ho 3+ in the Yb 3+/ Tm 3+/Ho 3+ triply doped NaGdF 4 nanorods. In addition, the ultrasmall NaGdF 4 nanocrystals also exhibit paramagnetic properties at 293 K. The measured magnetizations of the NaGdF 4:20%Yb 3+/0.2% Er 3+ and NaGdF 4 nanocrystals were about 1.49 and 1.86 emu/g at 20 kOe, respectively, which were close to the reported values of other nanoparticles for bioseparation. Moreover, the NaGdF 4 nanocrystals can be readily attracted by a small magnet, which shows it has potential application in cell isolating. It is expected that these multifunctional ultrasmall NaGdF 4 nanorods including tunable UC colors and intrinsic paramagnetic properties may have potential applications in color displays, biolables, bioseparation, and magnetic resonance imaging. © 2011 American Chemical Society.

Xu Y.,China Institute of Technology | Sun X.-Q.,China Institute of Technology | Shao L.,China Institute of Technology | Shao L.,Science and Technology on Electro Optical Information Security Control Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

The situation of researches on laser jamming to imaging detectors is analyzed and saturation effect of CCD under laser illumination is introduced. Combined with characteristics of CCD, diffraction limited point spread function (PSF) is applied to analyze the laser dazzled image and process of simulation is shown. Then simulated dazzled image is obtained and it is compared with actual image. With different laser powers, imaging performance parameters of simulated images are analyzed, such as Peak signal to noise ratio (PSNR), gray variation, definition, uniformity and so on. Experimental results show the feasibility and validity of laser jamming simulation. Moreover, changes of imaging performance parameters can provide useful references for further evaluation of laser jamming effect. © 2010 SPIE.

Li Y.,Science and Technology on Electro Optical Information Security Control Laboratory
2015 International Conference on Optoelectronics and Microelectronics, ICOM 2015 | Year: 2015

Connected component (CC) labeling is time consuming during image segmentation and object identification, especially when input images are large-scale and binary converting uses multi-threshold. So in this paper, we present a fast multi-level CC labeling by combining online threshold segmentation and a one-pass labeling algorithm, also a detailed architecture for hardware implementation is proposed. During labeling, firstly a gray image is converted to several binary data flows with different thresholds. Then they are marked by run-length code respectively with 2× 2 scanning windows, in the meantime, the equal labels between two adjacent rows are obtained by these windows for CC merging. By executing this process until the end of input image, the CC labels are obtained after one-pass image scanning. Our method is tested on more than 1000 gray images which resolution are 1920×1080. Experimental results show that our algorithm can extract the positions and areas of CC in multi-threshold binary images at least 50 frames per second (fps) on a Stratix IV FPGA platform running at 109.7 MHz. © 2015 IEEE.

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