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1
Content available Monte Carlo simulation of polarization of light back-scattered from randomly rough surfaces
Jiang Yuxiang, Li Zhenhua
Optica Applicata
|
2023
|
Vol. 53, nr 1
65--85
EN
Laser detection devices obtain target information from back-scattered light, such as lidar. The recognition rate can be improved by analyzing intensity and polarization of echo signal. In this paper, Monte Carlo method is used to generate a large number of randomly rough surfaces to simulate targets. Every rough surface is discretized into a large number of micro-surface elements. Stokes parameters of back-scattered light are calculated by numerical integration. Incident light is p-, s-, 45° linearly polarized light and right-hand circularly polarized light, respectively. Numerical results show that when s- and p-linearly polarized light incident on a metal rough surface, back-scattered light appears circularly polarized component. Metal rough surface resembles a wave plate with phase difference, with the fast axis parallel or perpendicular to the 45° direction. When linearly polarized light is incident on dielectric rough surface, back-scattered light has no circularly polarized component. Experimental data are consistent with the numerical results. The above research provides a new basis for laser detection device to identify metal targets from the environmental background.
2
Content available remote On Baltic herring morphometry and its impact on the backscattering properties
Gorska Natalia, Idczak Jakub
Oceanologia
|
2022
|
No. 64 (1)
198--211
EN
Previous studies, dedicated to backscattering properties of Baltic herring, have shown the different target strength (TS – which is a measure of fish capacity to scatter sound) values, for the same species in different regions and seasons. The intraspecies differentiation in fish physiology and morphology as well as fish swimbladder morphometry between herring aggregations, occupying various parts of the Baltic Sea, has been supposed as one of the reasons for the variability. The paper addresses analysis of herring swimbladder morphometry and its impact on TS of individuals from ICES subdivision 26, one of the areas where Poland is responsible for herring biomass estimation. The collection of the X-rays images for 74 herring individuals, sampled in this subdivision, was created. The two-dimensional digitized dorsal images of herring swimbladder and body, as well as the angles between the swimbladder and the body longitudinal axis, were used to compute the target strength. The differentiation of herring morphometry within particular fish size classes was analysed and its consequences for the averaged target strength within the class was discussed. The difference from the previous numerical studies, in which the simplified herring morphometry was used, was also demonstrated. The computational results were considered in regard to the available in situ measured data on Baltic herring TS. The study of the Baltic herring target strength is important for increasing accuracy of acoustic biomass estimation of this ecologically and economically important species.
3
Content available An acoustic study of zooplankton diel vertical migration in the Black Sea
Pezacki P. D., Gorska N., Soloviev V.
Hydroacoustics
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2017
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Vol. 20
139--148
EN
Reliable, rapid and non-invasive techniques are important for the monitoring of the ecosystem of the semi-enclosed Black Sea, especially sensitive to the human impact. Hydroacoustic techniques meet these requirements. In the study, the ADCP data (volume backscattering strength and water velocities), collected in the north-east part of the Black Sea in October 2014, were used to understand some biotic and abiotic processes in the environment. The study was motivated by the fact that the used ADCP mounted on the autonomous (moving vertically) platform provided measurements with significantly higher spatial resolution that it was in the previous hydroacoustical studies of Black Sea ecosystem. The main objective of the analysis was to determine the velocity of zooplankton diel vertical migration and understand the processes responsible for the variability of the volume backscattering strength.
4
Content available Influence of microphytobenthos photosynthesis on the spectral characteristics of the signal reflected from Baltic sandy sediments
Jaśniewicz D., Gorska N.
Hydroacoustics
|
2016
|
Vol. 19
165--171
EN
The use of hydracoustical techniques to classify benthic fauna and flora is one of the important challenges in present marine research. It is crucial to understand the microphytobenthos photosynthesis impact on the backscattering properties of the sea floor in the Baltic Sea, where the techniques are actively developed now. This motivated our study. The data used in the analysis was collected in the multiday laboratory experiment conducted in the frame of the grant of the National Science Centre, Poland (No. N306 773940). In this experiment, during changing light conditions (light/dark photocycles), the hydroacoustical backscattering data was acquired in the aquarium with a sandy bottom. The constant temperature and salinity conditions, typical for the Southern Baltic, were kept, and oxygen content was monitored. In this paper data collected at 280 kHz, was processed. It was studied how the energy of echo and power spectral density of the echo signal, are sensitive to the microphytobenthos photosynthesis.
5
Content available Impact of Microphytobenthos Photosynthesis on the Characteristics of the Echo Signal from Baltic Sandy Sediments
Gorska N., Kowalska-Duda E., Marszal J., Schmidt J., Klusek Z.
Archives of Acoustics
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2015
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Vol. 40, No. 3
395--405
EN
The understanding the influence of biological processes on the characteristics of the signals backscattered by the sea floor is crucial in the development of the hydroacoustical benthic habitat classification techniques. The impact of the microphytobenthos photosynthesis on the acoustical backscattering properties of the Atlantic sandy sediments was previously demonstrated by Holliday et al. (2004) and Wildman and Huettel (2012). To account for the sensitivity of the hydroacoustical classification techniques to the backscattering properties of local marine sediments, it is important to understand the microphytobenthos photosynthesis impact for the Baltic Sea where the techniques are being actively developed now. This is the main motivation of the paper. In the paper the influence of the microphytobenthos photosynthesis on the characteristics of the echo signals reflected by sandy sediments in the typical Baltic temperature and the salinity conditions is discussed. The interdisciplinary multiday laboratory experiment was conducted to study the impact of benthic microalgal photosynthesis on the characteristics of the echo signal reflected by sandy sediments. Hydroacoustical data were collected under controlled constant light, temperature and salinity conditions. The oxygen content at different levels of the water column was simultaneously monitored.
6
Content available remote Light scattering models of white blood cells and back-scattering distribution analysis of them
Wang Y. W., Bu M., Shang X. F., Yue Q. W.
Optica Applicata
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2011
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Vol. 41, nr 3
527--539
EN
Focusing on the light scattering technique and its application in cell identification, the analysis of the morphological structures of the WBCs (white blood cells) has been made, and the light scattering models of five types of the WBCs have been built. Based on the light scattering theory and applying numerical simulation techniques to a systematic study of the back-scattering intensity distribution of five types of the WBCs, some significant effects made by the internal and external morphological structures of the WBCs and the changes of their refractive index to their back-scattering distribution and certain relations between them have been found. Thus, the back-scattering theory and its application have been expanded, and it is very useful to improve the technique of cell identification.
7
Content available remote Dynamic light back-scattering with polarization gating and Fourier spatial filter for particle sizing in concentrated suspension
Hui Y., Gang Z., Guang D. S., Ren-jie Z., Ping-an M.
Optica Applicata
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2010
|
Vol. 40, nr 4
819--826
EN
We present here a new dynamic light scattering method for investigating the particle size in concentrated suspension. By using the polarization gating and Fourier spatial filter, the optical thickness through the sample is reduced and the multiple scattered light is suppressed. The method is systematically tested using suspensions of latex spheres of 100 nm with a wide range of concentrations. Compared to the current common methods for nanoparticle sizing in concentrated suspension, it has the advantage of simple structure and it is easy to debug and maintain.
8
Content available remote Acoustic mapping of the back-scattering interferometer signal in a CO2 laser
Wojaczek D. A., Chodorowski P., Dobrucki A. B., Witkowski J. S., Pliński E. F.
Optica Applicata
|
2010
|
Vol. 40, nr 4
909--919
EN
It is shown that a microphone placed in the laser plasma can be used for detection and observation of the optical phenomenon such as an optical feedback in a continuous wave regime of the laser operation. To observe the effect, a periodically moved external mirror has been used. The periodical changes of the optical beam intensity in the laser cavity generated changes in frequency and amplitude of the acoustic signal. In conclusion, the acoustic wave gives information about optical effects created in a waveguide CO2 laser.
9
Content available remote Elektronowy mikroskop skaningowy w badaniach struktury stopów odlewniczych
Gajewski M., Kasińska J.
Archiwum Odlewnictwa
|
2006
|
R. 6, nr 21/1
453-462
PL
W referacie przedstawiono wykorzystanie efektów emisji elektronów pierwotnych rozproszonych wstecznie do ujawniania struktury i identyfikacji faz poprzez wytwarzanie kontrastu kompozycyjnego i analizę składu chemicznego w elektronowym mikroskopie skaningowym współpracującym z mikroanalizatorem rentgenowskim EDS. Przestawiono zalety tej metody badawczej na przykładach badania: struktury wtrąceń niemetalicznych, struktury staliwa austenityczno - ferrytycznego Cr-Ni + Mo stabilizowanego niobem oraz struktury brązu B101.
EN
This paper submits useing effect of backscattered electrons emission for structure elicit and phases identifications through compounds contrast making and chemical analysis. The investigations were made by means of scanning electron microscopy (SEM) and energy dispersive X-Ray microanalysis (EDS). The advantages of this method are also described.
10
Content available remote Scattering of ultrasonic wave on a model of the artery
Wójcik J., Powałowski T., Tymkiewicz R., Lamers A., Trawiński Z.
Archives of Acoustics
|
2006
|
Vol. 31, No. 4
471-479
EN
The study was aimed at elaboration of a mathematical model to describe the process of acoustic wave propagation in an inhomogeneous and absorbing medium, whereas the wave is generated by an ultrasonic probe. The modelling process covered the phenomenon of ultrasonic wave backscattering on an elastic pipe with dimensions similar to the artery section. Later on, the numerical codes were determined in order to calculate the fields of ultrasonic waves, as well as backscattered fields for various boundary conditions. Numerical calculations make it possible to define the waveforms for electric signals that are produced when ultrasonic waves, being reflected and backscattered by an artery model, are then received by the ultrasonic probe. It is the signal which pretty well corresponds with the actual RF signal that is obtained during measurements at the output of an ultrasonic apparatus.
11
Content available Monte Carlo calculations of low energy positrons in silicon
Aydin A.
Nukleonika
|
2005
|
Vol. 50, nr 1
37-42
EN
Theoretical data for positron scattering from a thin silicon film and semi-infinite silicon are presented as a function of incident and outgoing angles and energies. These theoretical data of the scattering processes of low energy positrons penetrating into silicon were performed by Monte Carlo simulation. The simulation is based on the use of different types of differential cross sections for individual elastic and inelastic scattering i) inelastic scattering; Gryzinski's excitation function to simulate the energy loss and Liljequist's model to calculate the inelastic scattering cross section, ii) elastic scattering; the screened Rutherford differential cross section with the spin-relativistic factor. In calculations on positron traversing matter, it is important to know the transmission through medium, their path lengths, and their energy and angular distribution through matter. The simulation results are well agreed with experiments.
12
Content available remote Parameterization of light scattering for solving the inverse problem of determining the concentrations of the principal light scattering and absorbing admixtures in shelf waters
Pelevin V. N., Rostovtseva V. V.
Oceanologia
|
2001
|
No. 43 (4)
479-485
EN
A method for estimating the water backscattering coefficient was put forward on the basis of experimental data of diffuse attenuation coefficient for downwelling irradiance and irradiance reflectance. Calculations were carried out for open sea waters of different types and the spectral dependencies were found ("anomalous" spectra) and explained. On this basis, a new model of light backscattering on particles in the sea is proposed. This model may be useful for modelling remote sensing reflectance spectra in order to solve the inverse problems of estimating the concentration of natural admixtures in shelf waters
13
Content available Monte Carlo calculations of positron implantation profiles and backscattering probabilities in gold
Aydin A.
Nukleonika
|
2001
|
Vol. 46, nr 3
87-90
EN
The transport of charged particles through matter is worth considering for various applications. In this work, backscattering probabilities and mean penetration depths were calculated from the implantation profiles for positrons of energies 1-75 keV entering normally at various angles into a semi-infinite gold target. The theoretical results of backscattering probability and mean penetration depth are compared with other published [1, 3, 4, 10, 11, 13]. Monte Carlo calculations and experimental results for the semi-infinite gold target. In general, good agreement is observed.
14
Wykorzystanie rozproszenia Brillouina w miernictwie światłowodowym
Zakrzewski A.
Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne
|
1999
|
nr 12
835-841
PL
Przedstawiono jeden z mechanizmów rozpraszania światł
EN
The Brillouin scatteringe effect in the fibra and its
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