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Wyszukujesz frazę "Zhang, Y. H." wg kryterium: Autor

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    Wyświetlanie 1-9 z 9
    Tytuł:
    Fiber diameter influence on optical transport of dielectric particles along subwavelength optical fibers
    Autorzy:
    Zhang, Y.
    Lei, H.
    Li, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/173195.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    optical transport
    optical scattering force
    optical gradient force
    subwavelength optical fiber
    evanescent field
    Opis:
    We investigate a fiber diameter influence on optical transport of dielectric particles along subwavelength optical fibers using a near infrared laser of 1.55 μm wavelength. Theoretical analysis indicates that at 1.55 μm, the evanescent field at the fiber surface increases at first and then decreases with an increase of the fiber diameter from 600 nm to 1.6 μm, exhibiting a maximum at the fiber diameter of 950 nm. Based on three-dimensional finite-difference time-domain simulations, optical scattering forces acted on the dielectric particles and transport velocities of the particles were calculated for two fibers in the diameters of 930 nm and 1.5 μm. To support the theoretical analysis, experiments were performed using the two fibers to transport SiO2 particles (sizes of 530 nm and 1.5 μm) and TiO2 particles (size of 1.5 μm). The results show that with the same laser power launched into the two fibers, larger transport velocities can be obtained along the 930 nm diameter fiber.
    Źródło:
    Optica Applicata; 2013, 43, 4; 707-718
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Polarization properties of Gaussian–Schell model quantization field in a turbulent marine-atmosphere
    Autorzy:
    Zhao, Y.
    Xia, M.
    Wang, Q.
    Li, Y.
    Hu, Z.
    Sun, H.
    Zhang, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/173639.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    polarization fluctuation
    Gaussian–Schell model
    marine-atmosphere
    Kolmogorov turbulence
    Opis:
    Polarization properties of Gaussian–Schell model quantization field propagating through the Kolmogorov turbulence of a marine-atmosphere channel are studied based on the degree of quantum polarization. The effective photon annihilation and creation operators of Gaussian–Schell model quantization field propagation in a marine-atmosphere are developed by making use of the extended Huygens–Fresnel integral of quantum field. The effects of the outer scale on the degree of polarization can be neglected. As the source transverse coherent width, the number of received photons, the inner scale of turbulent eddies, and the source transverse radius decrease or the re- fractive index structure parameter increases, the degree of polarization decreases. In theory, we find that the polarization fade of marine-atmosphere turbulence channels is larger than that of terrene-atmosphere turbulence channels under same transport parameters and the channel with a stronger turbulence strength will possess a larger detection area of a polarization signal, which have potentially important implications for free-space quantum key distribution.
    Źródło:
    Optica Applicata; 2016, 46, 3; 335-345
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of dispersion order on the spectral degree of polarization of stochastic electromagnetic pulsed beams
    Autorzy:
    Wang, H.
    Ding, C.
    Zhang, Y.
    Zhao, Z.
    Pan, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/173625.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    stochastic electromagnetic Bessel–Gauss pulsed beams
    dispersive aperture lens
    pulse
    duration
    temporal coherence length
    Opis:
    The analytical expression for the cross-spectral density function of stochastic electromagnetic Bessel–Gauss pulsed beams through a dispersive aperture lens is derived and used to study the changes in the spectral degree of polarization in an optical focus system. The changes in the spectral degree of polarization at the focal plane and on the z-axis are performed in the case of dispersion-free, dispersion of the first, second, and higher orders, respectively. It is shown that the dispersion affects the peak value of the spectral degree of polarization, and the higher order dispersion leads to a more obvious effect on the peak value of the spectral degree of polarization at the focal plane. On the z-axis, the spectral degree of polarization in the dispersion-free case is different form that in the dispersion case, however, the dispersion of different orders almost has the same effect on the spectral degree of polarization. The results obtained in this paper may be crucial for high precision laser detection.
    Źródło:
    Optica Applicata; 2014, 44, 1; 147-158
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Research on a square Cassegrain-type solar concentrating reflector with a double pyramid
    Autorzy:
    Zhang, Y.
    Yang, H.
    Jiang, P.
    Mao, S.
    Yu, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/174264.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    concentrating reflector
    double pyramidal
    ray tracing
    Opis:
    A structure of a solar concentrating reflector is designed in this paper to improve the usage of solar energy. For the dark image which is the result of the secondary mirror in the new type of the Cassegrain solar concentrating system, a double pyramid system is used to improve this phenomenon. By eliminating the dark image, the system enhanced the concentration ratio and the working efficiency. Meanwhile, both the primary and secondary mirrors are shaped into a square section in order to get a better match with a square photovoltaic receiver. While the length of the primary mirror is 89m and the block ratio is 20%, the concentration ratio is equal to 118.86.
    Źródło:
    Optica Applicata; 2016, 46, 3; 461-471
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Feature extraction of molten pool for laser welding quality real-time inspection
    Autorzy:
    Zhang, J
    Yin, H
    Huang, H
    Yang, R
    Yang, J
    Li, Y
    Powiązania:
    https://bibliotekanauki.pl/articles/173597.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    laser materials processing
    process monitoring and control
    image analysis
    Opis:
    This paper proposed an image feature extraction method for laser welding molten pool inspection based on cellular neural network. TC4 titanium alloy thin plates were welded by Nd:YAG pulsed laser. A coaxial machine vision system was designed to acquire molten pool images. An auxiliary lighting source was employed to improve the molten pool image quality. By analyzing molten pool images, the welding defects such as fenestration or insufficient depth were identified. These results can be used as a feedback signal for laser power control. Experimental results showed that the proposed method can be used to improve laser welding quality.
    Źródło:
    Optica Applicata; 2015, 45, 4; 523-533
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical image encryption by using diffractive imaging with special constraint in the input plane
    Autorzy:
    Wang, Z.
    Wang, H.
    Yang, X.
    Zhang, P.
    Hou, C.
    Qin, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/173781.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    optical encryption
    diffractive imaging
    bilinear interpolation
    Opis:
    In order to simplify the optical setup and the encryption process, a diffractive-imaging-based optical encryption system using a single diffraction pattern is proposed. A predesigned binary mask is placed before the plaintext in the encryption process, and three randomly distributed phase only masks are placed in the optical path. Only one diffraction pattern needs to be recorded as ciphertext by CCD. In the decryption process, an iterative phase retrieval algorithm is applied, in which the predesigned binary mask acts as a support constraint in the input plane. After the iterative process, an interpolation operation for the zero-valued pixels is also implemented. The effectiveness and robustness of the proposal are demonstrated by numerical simulation results.
    Źródło:
    Optica Applicata; 2016, 46, 1; 57-69
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Image compression-encryption algorithm combining compressive sensing with log operation
    Autorzy:
    Chen, R.-L.
    Zhou, Y.
    Luo, M.
    Zhang, A.-D.
    Gong, L.-H.
    Powiązania:
    https://bibliotekanauki.pl/articles/174009.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    image encryption
    image compression
    compressive sensing
    log operation
    Opis:
    Based on compressive sensing and log operation, a new image compression-encryption algorithm is proposed, which accomplishes encryption and compression simultaneously. The proposed image compression-encryption algorithm takes advantage of not only the physical realizability of partial Hadamard matrix, but also the resistance of the chosen-plaintext attack since all the elements in the partial Hadamard matrix are 1, –1 or log 1 = 0. The proposed algorithm is sensitive to the key and it can resist various common attacks. The simulation results verify the validity and reliability of the proposed image compression-encryption algorithm.
    Źródło:
    Optica Applicata; 2018, 48, 4; 563-573
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Low atmospheric density measurement based on Rayleigh scattering of an ultraviolet laser
    Autorzy:
    Wang, R
    Yao, J.
    Zhong, K.
    Miao, Y.
    Cui, H.
    Zhao, X.
    Zhang, C.
    Powiązania:
    https://bibliotekanauki.pl/articles/174910.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    atmospheric density measurement
    Rayleigh scattering
    ultraviolet laser
    Opis:
    The qualitative measurement of low atmospheric density in the air flow field has been investigated in this paper. The supersonic flow field with Mach number of 1.5 around the NACA0006 aerofoil has been numerically simulated and the transient slight pressure and low density atmosphere have been experimentally determined based on Rayleigh scattering of a 266 nm ultraviolet laser. The scattering patterns have been effectively captured under different atmospheric pressure of 4.5, 92, 470 and 710 Pa with laser energy of only 0.5 mJ. It has been demonstrated that in the pressure range from 4.5 to 1100 Pa, corresponding to the atmospheric density from 4.8105×10–5 kg/m3 to 1.279×10–2 kg/m3, the scattering intensity of an ultraviolet laser is linear to the pressure and density with the slope coefficient of 0.00968 a.u./Pa and 0.83226 a.u./(kg/m3×10–3). It has been proved that Rayleigh scattering is a promising technology for observation of instantaneous and multidimensional distribution of a supersonic flow field.
    Źródło:
    Optica Applicata; 2013, 43, 3; 597-605
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Colloidal crystal cladded microfiber for refractive index sensing
    Autorzy:
    Yan, H. T.
    Zhao, X Y
    Zhang, Ch.
    Zhen, Z Q
    Li, Q Z
    Cao, J X
    Xia, L X
    Powiązania:
    https://bibliotekanauki.pl/articles/174902.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    microfibers
    colloidal crystals
    refractive index sensing
    Opis:
    We investigate the evanescent field of a microfiber wrapped by colloidal crystals. The microfiber has the diameter of about 1 μm that is drawn from a single-mode fiber with an alcohol lamp. The colloidal spheres are further attached to the microfiber through thermal evaporation, then they self-assemble to crystal-like structures. The 400 nm, 590 nm, and 710 nm-diameter SiO2 colloidal spheres are used, respectively. The spectral responses are studied theoretically and experimentally, and the results agree with each other. It is revealed that the evanescent field of a microfiber could be modulated by the photonic band-gap of colloidal crystals. This characteristic is very useful in refractive index sensing for liquids.
    Źródło:
    Optica Applicata; 2014, 44, 2; 309-315
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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