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Wyszukujesz frazę "Rayleigh scattering" wg kryterium: Temat


Wyświetlanie 1-6 z 6
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:
Investigation of a tunable and switchable multi-wavelength bidirectional Brillouin-erbium fiber ring laser
Autorzy:
Wang, F.
Yuan, R. Y.
Powiązania:
https://bibliotekanauki.pl/articles/2033954.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Rayleigh scattering
stimulated Brillouin scattering
four-wave mixing
laser
laser optics
Opis:
A multi-wavelength bidirectional Brillouin-erbium fiber ring laser with switchable Brillouin frequency spacing (BFS) is proposed and experimentally demonstrated. In the presented Brillouin-erbium ring laser, including an optical amplifier and a highly nonlinear fiber, and without any optical isolator, due to Rayleigh scattering, stimulated Brillouin scattering, and cascaded four-wave mixing initiated successively by the Brillouin pump (BP) light, the odd- and even-order Stokes lines are generated and circulate in the opposite direction in the ring cavity. The BP light and Stokes-induced Rayleigh backscattering light also simultaneously circulate in the ring cavity. Only by adjusting BP power, the gain competition between Brillouin based Stokes and cavity modes’ oscillation can be controlled, the laser output can be conveniently switched between single BFS and odd- or even-order double BFS. In addition, under the certain BP power conditions, the proposed multi-wavelength Brillouin-erbium fiber laser also can realize switchable odd- or even-order Stokes generation and Stokes generation with single BFS, with an increasing wavelength number in turn, only by simply adjusting pump power of the erbium-doped fiber amplifier. Stability and wavelength tunability of the proposed multi-wavelength bidirectional Brillouin-erbium fiber ring laser are also investigated, respectively.
Źródło:
Optica Applicata; 2021, 51, 3; 375-389
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Software-Defined Radio for Rayleigh and Raman Scattering Measurement in Optical Fibers
Autorzy:
Shatarah, I. S. M.
Więcek, B.
Powiązania:
https://bibliotekanauki.pl/articles/114286.pdf
Data publikacji:
2018
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
Rayleigh and Raman scattering
synchronous detection
silica optical fiber
optical frequency domain reflectometry
Opis:
A laboratory system for measuring the Raman scattering light in optical fiber is presented. The system is equipped with the developed driver for 5 mW/1550 nm laser diode, optical circulator, WDM filters to separate Rayleigh and Raman scattered light and InGaAs cooled photodiode to detect the weak scattered radiation. Instead of using expensive network analyzer we propose to use Software-Defined Radio, which ensures the necessary sensitivity and selectivity of detected signals. The preliminary results are presented for about 3 km – length single mode silica optical fiber.
Źródło:
Measurement Automation Monitoring; 2018, 64, 4; 112-115
2450-2855
Pojawia się w:
Measurement Automation Monitoring
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistics of Envelope of High-Frequency Ultrasonic Backscatter from Trabecular Bone: Simulation Study
Autorzy:
Litniewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/177928.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
trabecular bone
Rayleigh distribution
scattering
simulation
Opis:
The paper considers the application of statistical properties of backscattered ultrasonic signal for assessment of the trabecular bone status. Computer simulations were conducted to investigate the properties of the ultrasound pulse-echo signal, as it is received on the transducer surface after scattering in trabecular bone. The micro-architecture of trabecular bone was modeled by a random distribution of long and thin cylindrical scatterers of randomly varying diameters and mechanical properties, oriented perpendicular to the ultrasound beam axis. The received echo signal was calculated as a superposition of echoes from all the scatterers present in the scattering volume. The simulated signal envelope was used for statistical processing to compute various parameters like the mean amplitude, the amplitude MSR defined as the ratio of the mean to the standard deviation and the amplitude histogram. Results indicated that while for the well-defined trabeculae properties within the simulated bone structure the signal envelope values are Rayleigh distributed the significant departures from Rayleigh statistics may be expected as the thickness of trabeculae become random. The influence of the variation of mechanical properties of the bone tissue building the trabeculae on the bone backscattered signal parameters was not observed.
Źródło:
Archives of Acoustics; 2010, 35, 3; 349-360
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An extension to the Rayleigh–Gans formula: model of partially absorbing particles
Autorzy:
Komar, L
Kocifaj, M
Kohut, I
Powiązania:
https://bibliotekanauki.pl/articles/173693.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
scattering
absorption
spherical particle
Rayleigh-Gans approximation
Opis:
The Rayleigh–Gans (R–G) approximation is widely employed in various optical models to simulate the optical response of transparent media. However, the R–G concept can only succeed if the refractive index of scatterers approaches that of surrounding medium. In addition, the sizes of scattering domains are assumed to be small enough. Because of these reasons, the validity of R–G solution is fairly limited. In this paper, a semi-analytical extension to the R–G theory is introduced, resulting in an approximate formula for efficiency factor for scattering Qsca. It is proven numerically that this formula works much better than that for traditional R–G model. The computations have been made on absorbing particles with sizes comparable to or smaller than the wavelength of an incident radiation. The conventional R–G theory is either inapplicable or at least inappropriate for such particles.
Źródło:
Optica Applicata; 2013, 43, 2; 313-323
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrasonic Echosignal Applied to Human Skin Lesions Characterization
Autorzy:
Piotrzkowska, H.
Litniewski, J.
Szymańska, E.
Nowicki, A.
Powiązania:
https://bibliotekanauki.pl/articles/177296.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
statistics
K-distribution
Rayleigh distribution
ultrasonic scattering
human dermis
Opis:
The paper presents a classification of the healthy skin and the skin lesions (basal cell carcinoma) basing on a statistics of the envelope of ultrasonic echoes. The echoes envelopes distributions were modeled using Rayleigh and K-distribution. The distributions were compared with empirical data to find which of them better models the statistics of the echo-signal obtained from the human skin. The results indicated that the K-distribution provides a better fit. Also, a characteristic parameter of the K-distribution, the effective number of scatterers (M), was investigated. The values of the M parameter, obtained for the skin cancer (basal cell carcinoma), were lower as compared to those obtained for the healthy skin. The results indicate that the statistical quan- titative ultrasound parameters have a potential for extracting information useful for characterization of the skin condition.
Źródło:
Archives of Acoustics; 2012, 37, 1; 103-108
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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