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mgr inż. Maciej Kraszewski
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total: 25
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Year 2020
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Application of the Monte Carlo algorithm for solving volume integral equation in light scattering simulations
PublicationVarious numerical methods were proposed for analysis of the light scattering phenomenon. Important group of these methods is based on solving the volume integral equation describing the light scattering process. The popular method from this group is the discrete dipole approximation (DDA). DDA uses various numerical algorithms to solve the discretized integral equation. In the recent years, the application of the Monte Carlo (MC)...
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Convergence of Monte Carlo algorithm for solving integral equations in light scattering simulations
PublicationThe light scattering process can be modeled mathematically using the Fredholm integral equation. This equation is usually solved after its discretization and transformation into the system of algebraic equations. Volume integral equations can be also solved without discretization using the Monte Carlo (MC) algorithm, but its application to the light scattering simulations has not been sufficiently studied. Here we present implementation...
Year 2019
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Zastosowanie czasowo-częstotliwościowej analizy sygnałów dla poprawy właściwości metrologicznych systemów optycznej tomografii koherentnej
PublicationOptyczna tomografia koherentna (OCT) jest metodą obrazowania wewnętrznej struktury obiektów rozpraszających promieniowanie optyczne. Metoda ta wykorzystuje interferometrię niskokoherentą do pomiaru czasu przelotu promieniowania wstecznie rozproszonego od elementów struktury obrazowanego obiektu z rozdzielczością w zakresie od jednego do kilkunastu mikrometrów. Rozprawa dotyczy dwóch rozszerzeń metody OCT. Pierwsze z nich – polaryzacyjna...
Year 2017
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EXAMINATION OF SOL-GEL DERIVED HYDROXYAPATITE ENHANCED WITH SILVER NANOPARTICLES USING OCT AND RAMAN SPECTROSCOPY
PublicationHydroxyapatite (HAp) has been attracting widespread interest in medical applications. In a form of coating, it enables to create a durable bond between an implant and surrounding bone tissues. With addition of silver nanoparticles HAp should also provide antibacterial activity. The aim of this research was to evaluate the composition of hydroxyapatite with silver nanoparticles in a non-destructive and non-contact way. For control measurements...
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Simulating propagation of coherent light in random media using the Fredholm type integral equation
PublicationStudying propagation of light in random scattering materials is important for both basic and applied research. Such studies often require usage of numerical method for simulating behavior of light beams in random media. However, if such simulations require consideration of coherence properties of light, they may become a complex numerical problems. There are well established methods for simulating multiple scattering of light (e.g....
Year 2016
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Coherent-wave Monte Carlo method for simulating light propagation in tissue
PublicationSimulating propagation and scattering of coherent light in turbid media, such as biological tissues, is a complex problem. Numerical methods for solving Helmholtz or wave equation (e.g. finite-difference or finite-element methods) require large amount of computer memory and long computation time. This makes them impractical for simulating laser beam propagation into deep layers of tissue. Other group of methods, based on radiative...
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Nanoparticles displacement analysis using optical coherence tomography
PublicationOptical coherence tomography (OCT) is a versatile optical method for cross-sectional and 3D imaging of biological and non-biological objects. Here we are going to present the application of polarization sensitive spectroscopic OCT system (PS-SOCT) for quantitative measurements of materials containing nanoparticles. The PS-SOCT combines the polarization sensitive analysis with time-frequency analysis. In this contribution the benefits...
Year 2015
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Advanced Monte Carlo simulator of the polarization-sensitive optical coherence tomography systems
PublicationSimulations of the optical coherence tomography (OCT) systems using the Monte Carlo method is a widely explored research area. However, there are several difficulties that need to be overcome in order to properly model the OCT imaging with the Monte Carlo algorithm. First of all, the temporal and the spatial coherence of the scattered light need to be considered, since OCT is based on the interference phenomenon. For the same reason,...
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Efficient signal processing in spectroscopic optical coherence tomography
PublicationSpectroscopic optical coherence tomography (SOCT) is an extension of a standard OCT technique, which allows to obtain depth-resolved, spectroscopic information on the examined sample. It can be used as a source of additional contrast in OCT images e.g. by encoding certain features of the light spectrum into the hue of the image pixels. However, SOCT require computation of time-frequency distributions of each OCT A-scan, what is...
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Nano-particle doped hydroxyapatite material evaluation using Spectroscopic Polarization Sensitive Optical Coherence Tomography
PublicationBio-ceramics such as hydroxyapatite (HAp) are widely used materials in medical applications, especially as an interface between implants and living tissues. There are many ways of creating structures from HAp like electrochemical assisted deposition, biomimetic, electrophoresis, pulsed laser deposition or sol-gel processing. Our research is based on analyzing the parameters of the sol-gel method for creating thin layers of HAp....
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Optical Coherence Tomography for nanoparticles quantitative characterization
PublicationThe unique features of nanocomposite materials depend on the type and size of nanoparticles, as well as their placement in the composite matrices. Therefore the nanocomposites manufacturing process requires inline control over certain parameters of nanoparticles such as dispersion and concentration. Keeping track of nanoparticles parameters inside a matrix is currently a difficult task due to lack of a fast, reliable and cost effective...
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Simulating coherent light propagation in a random scattering materials using the perturbation expansion
PublicationMultiple scattering of a coherent light plays important role in the optical metrology. Probably the most important phenomenon caused by multiple scattering are the speckle patterns present in every optical imaging method based on coherent or partially coherent light illumination. In many cases the speckle patterns are considered as an undesired noise. However, they were found useful in various subsurface imaging methods such as...
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Spectral measurement of birefringence using particle swarm optimization analysis
PublicationThe measurement of birefringence is useful for the examination of both technical and biological objects. One of the main problems is that the polarization state of light in birefringent media changes periodically. Without the knowledge of the period number, the birefringence of a given medium cannot be determined reliably. We propose to analyse the spectrum of light in order to determine the birefringence. We use a Particle Swarm...
Year 2014
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Comment on "Quantitative comparison of analysis methods for spectroscopic optical coherence tomography"
PublicationIn a recent paper by Bosschaart et al. [Biomed. Opt. Express 4, 2570 (2013)] various algorithms of time-frequency signal analysis have been tested for their performance in blood analysis with spectroscopic optical coherence tomography sOCT). The measurement of hemoglobin concentration and oxygen saturation based on blood absorption spectra have been considered. Short time Fourier transform (STFT) was found as the best method for...
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Novel approach to modeling spectral-domain optical coherence tomography with Monte Carlo method
PublicationNumerical modeling Optical Coherence Tomography (OCT) systems is needed for optical setup optimization, development of new signal processing methods and assessment of impact of different physical phenomena inside the sample on OCT signal. The Monte Carlo method has been often used for modeling Optical Coherence Tomography, as it is a well established tool for simulating light propagation in scattering media. However, in this method...
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Parallel multithread computing for spectroscopic analysis in optical coherence tomography
PublicationSpectroscopic Optical Coherence Tomography (SOCT) is an extension of Optical Coherence Tomography (OCT). It allows gathering spectroscopic information from individual scattering points inside the sample. It is based on time-frequency analysis of interferometric signals. Such analysis requires calculating hundreds of Fourier transforms while performing a single A-scan. Additionally, further processing of acquired spectroscopic information...
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Polarization-sensitive optical coherence tomography for ceramic materials inspection
PublicationCeramics production is looking for a fast, reliable and non-destructive method that can be implemented on site for defect detection and analysis. In this paper we present polarization-sensitive optical coherence tomography (PS-OCT) as a method for defect inspection. Proposed extensions to standard OCT provide additional information for complete characterization of tested object. We compare OCT and microscope imaging that can easily...
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Przemysłowe zastosowania optycznej tomografii koherentnej
PublicationOptyczna tomografia koherentna (OCT) jest nowoczesną techniką obrazowania wewnętrznej struktury obiektów rozpraszających światło. Główne zastosowania OCT należą do dziedziny obrazowania medycznego, jednak prowadzony jest także szereg badań nad przemysłowymi aplikacjami tej metody. Zaletą OCT jest możliwość tomograficznego obrazowania z rozdzielczością rzędu pojedynczych mikrometrów w sposób szybki i nieinwazyjny. W niniejszym artykule...
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Time-frequency analysis in optical coherence tomography for technical objects examination
PublicationOptical coherence tomography (OCT) is one of the most advanced optical measurement techniques for complex structure visualization. The advantages of OCT have been used for surface and subsurface defect detection in composite materials, polymers, ceramics, non-metallic protective coatings, and many more. Our research activity has been focused on timefrequency spectroscopic analysis in OCT. It is based on time resolved spectral analysis...
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Zastosowania optycznej tomografii koherentnej w protetyce dentystycznej
PublicationOptyczna tomografia koherentna (OCT) jest metodą obrazowania tomograficznego znajdującego coraz więcej zastosowań również w stomatologii i protetyce dentystycznej. O atrakcyjności tej metody stanowi możliwość wizualizacji wnętrza badanych obiektów w sposób nieniszczący i nieinwazyjny oraz rozdzielczość uzyskiwanych obrazów dorównująca możliwościom mikroskopii optycznej. W niniejszym artykule przedstawiono wyniki wstępnych badań...
Year 2013
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In-situ optical diagnostics of boron-doped diamond films growth
PublicationInterferometry is a desirable method for in-situ measurement of thin, dielectric film growth, as it don't modify conditions of film deposition. Here we present interferometrical measurements of thickness of doped diamond films during Chemical Vapor Deposition (CVD) process. For this purpose we used a semiconductor laser with a 405nm wavelength. Additional ex-situ measurement using spectral interferometry and ellipsometry...
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Laser reflectance interferometry system with a 405 nm laser diode for in-situ measurement of CVD diamond thickness
PublicationIn situ monitoring of the thickness of thin diamond films during technological processes is important because it allows better control of deposition time and deeper understanding of deposition kinetics. One of the widely used techniques is laser reflectance interferometry (LRI) which enables non-contact measurement during CVD deposition. The authors have built a novel LRI system with a 405 nm laser diode which achieves better...
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Pomiar kąta zwilżania z wykorzystaniem regresji gaussowskiej
PublicationKat zwilżania stanowi wielkość fizyczną umożliwiającą ocenę wielu parametrów charakteryzujących ciecze i ciała stałe o płaskich powierzchniach. W pracy zaprezentowano metodę wyznaczania kąta zwilżania na podstawie analizy cyfrowego obrazu kropli cieczy. Do obliczenia katą zwilżania wykorzystano algorytm regresji gaussowskiej. Umożliwia on ocenę kata miedzy dwiema powierzchniami, bez konieczności reprezentowania ich za pomocą funkcji o...
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Zastosowanie symulacji metodą różnic skończonych w dziedzinie czasu (FDTD) w kształceniu inżynierów w zakresie optyki i elektrodynamiki
PublicationZrozumienie zjawisk związanych z propagacją fal elektromagnetycznych stanowi kluczowy etap kształcenia inżynierów w dziedzinach związanych z optyką, elektroniką oraz telekomunikacją. Oprócz opanowania aparatu matematycznego oraz metod projektowych istotne jest intuicyjne zrozumienie treści przekazywanych podczas kursów optyki i elektrodynamiki. W realizacji tego celu praktyczną pomoc dydaktyczną stanowić mogą wizualizacje i symulacje...
Year 2012
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Hydroxyapatite films as biocompatibile coating for artifical bone
PublicationW artykule została szczegółowo opisana budowa kości oraz materiał biokompatybilny hydroksyapatyt (HAp). Autorzy wykazali jak wielkie podobieństwo do budowy kości przejawia sztuczny hydroksyapatyt. opisali syntezy powłoki z HAp.
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