Evaluation of laser beam interaction with carbon based material: Glassy carbon

U ovom radu se analizira interakcija laserskih snopova sa ugljeničnim materijalom (staklasti ugljenik). Korišćen je Nd3+:YAG lasera (1.06 μm, odnosno bliska IC oblast) u ms režimu rada sa snopovima različitih gustina energije. U svim eksperimentima, u primenjenom režimu rada, uočene su površinske povrede na uzorku. Povrede nastale dejstvom lasera su analizirane optičkim i SEM mikroskopima. Program Image J je korišćen za kvantitativnu analizu nastalih povreda na osnovu mikrografa dobijenih optičkom i SEM mikroskopijom. Temperaturna raspodela u izloženom uzorku je dobijena numeričkom simulacijom zasnovanom na programskom paketu COMSOL Multiphysics 3.5 u ograničenom opsegu energija.Laser beam interaction with carbon based material (glassy carbon) is analyzed in this paper. A Nd3+:YAG laser beam (1.06 μm, i.e., near infrared range (NIR)) in ms regime with various energy densities is used. In all experiments, provided in applied working regimes, surface damages have occurred. The results of laser damages are analyzed by light and scanning electron microscopy (SEM). Image J software is used for quantitative analysis of generated damages based on micrographs obtained by light and SEM microscopes. Temperature distribution in the exposed samples is evaluated by numerical simulations based on COMSOL Multiphysics 3.5 software in a limited energy range

Laser parameters optimization for the artifacts silver coated surfaces cleaning

In recent decades, lasers have become the devices that came out of research laboratories and are widely used in industry, engineering, medicine, arts, etc. Among the many applications, lasers have found a place in the conservation of cultural heritage as a source of radiation in the modern diagnostic techniques, cleaning and scanning objects of priceless value [1]. Their importance in cleaning of cultural heritage objects is based on the properties of these techniques, such as high sensitivity, nondestructivity, selectivity, flexibility, on-site applicability and others. Laser techniques application in metal artifacts cleaning has to be carefully evaluated due to complex phenomena in laser–metal interaction and specificity of every artifact item. There is a large variety of metal materials and their combinations in cultural heritage. Also, the different organic and inorganic encrustations and corrosion products in different progression stage can be found on artifacts surfaces [2,3]. Therefore, the optimization of laser parameters for safe and effective metal artifacts cleaning process is important step in order to avoid unwanted side-effects such as changes in the color or grater surface damages. A specific field of the metal surface laser cleaning is the cleaning of thin metal foils and coated surfaces. In cultural heritage such examples are metal yarns on the textile embroidery [4, 5]. Often, these yarns are coated with some precious metal as are silver or gold. This paper presents a study of laser cleaning parameters for safe and effective cleaning of silver coated copper metal yarns. In that purpose the preliminary investigation are performed on silver coated copper plate. That investigation involve numerical modeling of laser– silver coated copper plate interaction and experimental irradiation of real sample surface with pulsed nanosecond Nd:YAG laser by changing laser parameters as are wavelength, laser beam energy and number of pulses. The numerical 3D model of the generated heat on the silver coated copper plate was obtained using the COMSOL Multiphysics software package and was carried out with the aim to define the temperature distribution around the irradiated zone and the maximum temperatures. Optical microscopy, SEM and EDX analysis are used for the diagnosis of the morphological and chemical effects of laser irradiation on real sample surface. Obtained results are compared with results of laser irradiation analyses on naturally tarnished metal yarns embroidery from museum sample. This investigation confirms that Nd:YAG lasers can be successfully used for metal yarns cleaning. Application of adequate numerical model can provide an opportunity for a faster and cheaper determination of the cleaning process optimum values range. Some parameters for successfully and safely cleaning of silver coated copper surface were determined

Laser beam drilling and cutting of PMMA

Due to its excellent mechanical, chemical and optical properties, also on fatigue, polymethilmetacrylate (PMMA) is widely used for many purposes. PMMA has a reputation as a material that cannot be machined well, but, its elasticity and toughness enable its shaping by the deformation processes. Laser drilling and cutting are also available techniques for PMMA sheets shaping, used when both mechanical and optical PMMA properties must be preserved. In this work, the influence of CO2 laser cutting/drilling on transparent and coloured PMMA surfaces is investigated, as well as by the other laser systems. The cut surfaces were investigated by a light microscopy and, on those surfaces, the average surface roughness Ra was measured. The material zone affected by the laser beam during the cutting process was monitored by a thermal imaging, and theoretical simulations of temperature distribution in this area were performed using the various versions of COMSOL packages

Monitoring of a ceramic surface temperature field induced by pulsed Nd: YAG laser

Temperature distribution induced by laser radiation is a very important parameter for an efficient and safe application of lasers in different ceramic processing techniques. This paper presents the results of an infrared thermography (IRT) application for monitoring temperature distribution on a ceramic surface during Nd: YAG laser irradiation with different fluences and 8ns pulse duration. FLIR, E40 and SC7200 IR cameras were used with the aim of recording the maximum temperature in the irradiated zones. It was expected that IRT could give some information related to the heat affected zone and possible damage to the base material; however, the results have shown that IR cameras, even those with high performance such as SC7200, cannot record the maximum temperature value at the moment of laser operation, but only the average temperature of the bulk sample material after laser pulses. The results of the numerical simulation have confirmed the value of the thermographic measurements. The microstructure and micromorphology of the ceramic surface before and after the laser treatment were analysed by optical and scanning electron microscopy as well as by examining the roughness of the irradiated and non- irradiated surfaces, while the micromechanical changes were analysed by comparing the micro-hardness of the irradiated and non-exposed surfaces

Laser interaction of interest for materials in systems and components in energy transformation in linear and nonlinear ranges

Materijali, sistemi i komponente za transformaciju energije su veoma različiti po dimenzijama i principima funkcionisanja. Nekoliko generacija u mnoštvu sistema i transformacija, proširilo se, čak generišući nova imena od nekadašnjih samo pretvarača, do aktuatora, senzora. Među savremenim sistemima i dalje su u upotrebi merni uređaji i komponente, koji se koriste u naučnim institutima, kompanijama, aplikacijama u mass-media primenama, ali i dugogodišnji fotomultiplikatori sa organskim i neorganskim kristalima. Tanki filmovi doživljavaju širenje aplikacija i oblika. Pored rada nekih sistema, u ovom radu se razmatraju vreme života za razmatrane slučajeve, snopne tehnike i različite kombinacije tehnika. Razmatrani su neki režimi rada, kao što su rad u Q-switch režimu, režimu slobodne generacije, i cw, kao i izloženost kratkim impulsima elemenata na bazi Si / solarnih ćelija i drugih savremenih materijala, koji se tiču transformacija energije. Razmatraju se povrede nastale određenim vrstama lasera.Material, systems and components for energy transformation are very different in dimensions and principles of operation. Several generations in a multitude of systems and transformations, have expanded, even generating new names, from former to actuators and sensors. Among contemporary systems, measuring devices and components, used in scientific institutes, companies, mass-media applications etc., but also long-standing photomultipliers with organic and inorganic crystals, are still in use. Thin films are experiencing expansion of applications and forms. Besides operation of some systems, in this paper are considered the time of life for considered cases, beam techniques and various technique combinations. Some operation regimes, as operation in - switch mode, free generation regime, as well as cw, are considered, as well as exposures to short pulses of elements based on Si / solar cells and other contemporary materials, concerning energy transformations. The damages caused with certain types of lasers are considered.11th International Conference on Renewable Electrical Power Sources : November 2-3, Belgrade, 2023

Contemporary problems of transmission and interaction of quantum generators with material

Savremena problematika vezana za kvantne generatore u optičkom i RF delu spektra traži kao eksperimentalnu podršku vrlo kompleksne i skupe sisteme i komponente. Zbog toga su računarske simulacije neizbežne u osnovi razvoja mnogih sistema. U radu se autori bave problematikom dizajna optičkih vlakana i drugih komponenata u svrhe modulacija i simulacija u makroskopskim komponentama optičkih sistema. U drugom delu rada se primenom softverskih aplikacija ocenjuju eksperimentalni rezultati interakcije sa kvantnim generatorima na odabranoj vrsti materijala.Contemporary issues related to the quantum generators in the optical and RF spectral ranges required as part of the experimental support very complex and expensive systems and components. Therefore, the simulation is basically inevitable development of many systems. The authors deal with the problem of design of optical fiber and other components for the purpose of modulation and simulation of optical components in macroscopic systems in this paper. In the second part of it the application of other software types applications evaluated experimental results of interaction for selected type of material with the quantum generators

Откривање хипотензије током спиналне анестезије за царски рез континуираним неинвазивним праћењем артеријског притиска и интермитентним осцилометријским праћењем крвног притиска код болесница третираних ефедрином или фенилефрином

Introduction/Objective. Despite frequent side effects such as hypotension, spinal anesthesia (SA) is still one of the best anesthetic methods for elective cesarean section (CS). Intermittent, oscillometric, noninvasive blood pressure monitoring (NIBP) frequently leads to missed hypotensive episodes. The objective was to compare continuous non-invasive arterial pressure (CNAP) monitoring with NIBP in the terms of efficiency to detect hypotension. Methods. In this study, we compared CNAP and NIBP monitoring for hypotension detection in 76 patients divided into two groups of 38 patients treated with ephedrine (E) or phenylephrine (P), during threeminute intervals, starting from SA, by the end of the surgery. Results. In E group, significantly lower mean systolic blood pressure (SBP) values with CNAP compared with NIBP (p = 0.008) was detected. By monitoring CNAP, we detected 31 (81.6%) hypotensive patients in E group and significantly lower number, 20 (52.6%), with NIBP (p = 0.001), while in P group CNAP detected 34 patients (89.5%) and NIBP only 18 (47.3%), p = 0.001. By monitoring CNAP, we detected significantly higher number of hypotensive intervals in E and P groups (pУвод/Циљ Упркос честим нежељеним ефектима као што је хипотензија, спинална анестезија је и даље техника избора за планирани царски рез. Интермитентно неинвазивно праћење крвног притиска често не детектује хипотензивне епизоде. Циљ ове студије је био да се упореди континуирано неинвазивно праћење артеријског притиска са интермитентним неинвазивним праћењем крвног притиска у смислу ефикасности у откривању хипотензије.Методе Упоређивани су системи за континуирано неинвазивно праћење артеријског притиска и интермитентно неинвазивно праћење крвног притиска ради детекције хипотензије код 76 болесница подељених у две групе од по 38 болесница, третираних ефедрином (Е) или фенилефрином (Ф), на свака три минута, почевши од спиналне анестезије па све до краја операције.Резултати У групи Е су детектоване знатно ниже средње вредности систолног крвног притиска континуираним неинвазивним праћењем артеријског притиска у поређењу са интермитентним неинвазивним праћењем крвног притиска (p = 0,008). Континуираним неинвазивним праћењем артеријског притиска детектована је 31 (81,6%) хипотензивна болесница у групи Е и знатно мањи број, 20 (52,6%) болесница, интермитентним неинвазивним праћењем крвног притиска (p = 0,001), док је у групи Ф континуираним неинвазивним праћењем артеријског притиска детектована хипотензија код 34 болеснице (89,5%), а интермитентним неинвазивним праћењем крвног притиска код 18 (47,3%) болесница, p = 0,001. Континуираним неинвазивним праћењем артеријског притиска детектован је знатно већи број хипотензивних епизода у групама Е и Ф (p < 0,001). pH вредности умбиликалне крви биле су значајно ниже код хипотензивних у односу на нормотензивне болеснице у групама Е и Ф, и са континуираним неинвазивним праћењем артеријског притиска и интермитентним неинвазивним праћењем крвног притиска, респективно (p < 0,001, p = 0,027 у групи Е, и p = 0,009, p < 0,001 у групи Ф).Закључак Континуирано неинвазивно праћење артеријског притиска је много ефикасније у откривању хипотензије током царског реза у спиналној анестезији, што омогућава бржи третман и мање нежељених ефеката код мајке и новорођенчета

Materials, new technological trends, interaction modeling and the role of quantum generators - lasers today

Interakcija lasera sa materijalom je već dugo godina aktuelna sa mnogo rešenja, koja su postala komercijalna i gde se i ne stavlja u prvi plan da je reč o laserskom izvoru. To se utapa u elionska rešenja i poređenja delovanja snopova plazme, vode, neutrona, mikrotalasa. Razvijaju se osnovni teorijski i prakrtični evaluirani modeli. U modeliranju, modeli se dalje razvijaju, često se odmah prelazi na numeriku i u zavisnosti od energije / snage, repeticije radne laserske stanice, mogu se birati aproksimacije. U radu će se na osnovu eksperimentalnih izlaganja snopovima formirati niz pretpostavki o predviđanju i krojenju svojstava starog materijala mogućim novim, izazvanim modifikacijama različitim tehnikama. Posebno će se razmotriti i slučajevi gde se ne zanemaruju efekti uzmaka i ovaj pristup je takođe prikazan, kao i sprega sa akustičnim pojavama. Svojstva materijala biće pokrivena novim spektroskopskim podacima, odnosno komparativnošću ili sagledavanjem materijala iz različitih uglova gledanja, pri čemu podudaranje / nepodudaranje sa teorijskim prilazom, samo po sebi, daje novi pogled na materijale. S druge strane, traže se paralelni procesi koji su prisutni tokom interakcije , ali usled pojave nelinearnih efekata pri većim intenzitetima dolazi do promene mesta raznih pragova za njihovo nastupanje (kao stimulativni procesi, indukovani, i koji se pojavljuju pored spontanih). Kako se i sam lasing pojavljuje kao deo interakcije stimulisane svetlosti / zračenja sa materijalom, posmatra se i pitanje koeficijenata korisnog dejstva lasera i pragovi lasing-а. Postavlja se i paralela interferometrija / holografija / tomografija sa atributom laserska. Izveli smo naše simulacije za neke od procesa interakcije / rasejanja i eksperimentalne ekspozicije različitim tipovima lasera.The interaction of lasers with material has been current for many years with many solutions,which have become commercial and where it is not brought to the fore that it is a laser source. It is drowned in elion solutions and compares the effects of plasma beams, water, neutrons, microwaves. Basic theoretical and practical evaluated models are developed. In modeling, models are further developed, often immediately switching to numerics and depending on the energy /power, repetitions of the working laser station, approximations could be chosen. In the paper, on the basis of experimental exposures to beams, a series of assumptions will be formed about the forecast and tailoring of the properties of the old material with possible new ones, caused by modifications with various techniques. Special consideration will also be given to cases where the effects of recoil are not neglected and this approach is also shown, as well as coupling with acoustic phenomena. The properties of materials will be covered with new spectroscopic data, or the comparability or seeing of materials from various angles of view, where matching / non-matching with the theoretical approach, in itself, gives a new view of materials. On the other hand, parallel processes are sought, which are present during the interaction, but due to the appearance of non- linear effects at higher intensities, there is a change in the place of various thresholds for their occurrence (as stimulating processes, induced, which appear in addition to spontaneous ones). As lasing itself appears as part of the interaction of stimulated light /radiation with the material, the question of the coefficients of the useful effect of the laser and the thresholds of lasing is also observed. Parallel interferometry / holography / tomography with laser attribute is also set up. We performed our simulations for some of the interaction / scattering processes and experimental exposures to different types of lasers.Scientific Conferences Book LVIII Department of natural-mathematical and technical Sciences Book 5

Испитивање микроморфолошких и микрохемијских промена на посребреној бакарној плочици третираној Nd:YAG ласером

Овим радом су обухваћена истраживања која су имала за циљ одређивање микроморфолошких, микрохемијских и физичких промена које настају деловањем Nd:YAG ласером на посребрену бакарну плочицу. Посребрена плочица је изабрана јер се посребривање често користи у електронској индустрији, израда оптичких компонената, за израду накита, а такође и за израду посребрених нити (срма) корисћене за вез на музејским или савременим, одевним предметима. Варирана је флуенца за три таласне дужине Nd:YAG ласера. Дијагностику зона деловања ласером је вршена оптичком и скенирајућом електронском микроскопијом и EDX анализом. Примењена су термографска испитивања и нумеричке методе за одређивање зоне ширења топлоте индуковане ласером