Ming Qian

Nanjing University of Science and Technology, Nan-ching, Jiangsu Sheng, China

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Publications (3)5.22 Total impact

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    ABSTRACT: Our recent work revealed that speckles can be formed when nanofluids containing a proper volume fraction of nanoparticles are illuminated by a monochromatic laser beam [Qian M, Liu J, Yan M-S, Shen Z-H, Lu J, Ni XW, et al. Investigation on utilizing laser speckle velocimetry to measure the velocities of nanoparticles in nanofluids. Opt Express 2006; 14: 7559–66]. In this paper, two different physical models are established to figure out the speckle-formation mechanism. The photon–nanoparticle-collision model emphasizes the random collisions between photons and nanoparticles, and Monte Carlo method is used to simulate how the incident photons move in the vessel containing nanofluids. However, in the electric-dipole model, each illuminated nanoparticle becomes an electric dipole and sends out scattering lights, and the coherent addition of the scattering lights from nanoparticles is numerically calculated. Finally, from the numerical results, the speckle-formation mechanism is figured out.
    Optics and Lasers in Engineering 06/2008; 46(6):461-468. · 1.70 Impact Factor
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    ABSTRACT: Our recent work revealed that, when nanofluids containing a modest volume fraction of nanoparticles are illuminated by a parallel monochromatic laser beam, speckles would be formed. Therefore, it is realized that Laser Speckle Velocimetry can be used to measure the velocities of nanoparticles in nanofluids.1 This paper aims to investigate the laser transmission properties of nanofluids via experiments and numerical simulations, so as to determine the proper conditions for the formation of speckles. First, experiments are performed to measure the light transmittance of nanofluids at different laser power and different particle volume fraction. Then, Monte Carlo simulations are carried out based on a physical model considering random collisions between photons and nanoparticles to simulate light propagation in nanofluids. The numerical results are in good agreement with the experimental results, and a final conclusion is drawn that the particle volume fraction and particle size are the prime factors that influence the light transmittance.
    Proc SPIE 01/2007;
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    ABSTRACT: Laser speckle velocimetry (LSV) is presented to measure the velocities of nanoparticles in nanofluids and its feasibility is verified in this paper. An optical scattering model of a single nanoparticle is developed and numerical computations are done to simulate the formation of the speckles by the addition of the complex amplitudes of the scattering lights from multiple nanoparticles. Then relative experiments are done to form speckles when nanofluids are illuminated by a laser beam. The results of the experiments are in agreement with the numerical results, which verify the feasibility of utilizing LSV to measure the velocities of nanoparticles in nanofluids.
    Optics Express 09/2006; 14(17):7559-66. · 3.53 Impact Factor