Results on fabrication of Au nanostructures by laser ablation in open air are presented. The ablation of the Au target is performed in air environment by nanosecond laser pulses delivered by Nd:YAG laser system operated at λ = 355 nm. Due to the high density of the ambient atmosphere, the intensive collisions of the plume spices result in formation of nanoparticles and aggregates by condensation close to the target. The produced nanoagregates are deposited on a quartz substrate where grow in a specific nanostructure. Diagnostics of the laser-generated plasma for the laser fluences used in this study is performed. Study based on change of ambient conditions shows that the increase of the air pressure from 10 Torr to atmospheric one leads to transition from thin film to porous structures. It is found that the surface morphology of the structures produced by pulsed laser deposition (PLD) in open air strongly depends on the substrate-target distance. The electrical properties of the obtained structures are studied by measurement of their electrical resistance. It is found that the conductivity of the structures strongly depends on their morphology. The fabricated structures have potential for application in the field of electronics and sensors.
{"title":"Fabrication of Au nanostructures by pulsed laser deposition in air","authors":"R. Nikov, A. Dikovska, N. Nedyalkov, P. Atanasov","doi":"10.1117/12.2262274","DOIUrl":"https://doi.org/10.1117/12.2262274","url":null,"abstract":"Results on fabrication of Au nanostructures by laser ablation in open air are presented. The ablation of the Au target is performed in air environment by nanosecond laser pulses delivered by Nd:YAG laser system operated at λ = 355 nm. Due to the high density of the ambient atmosphere, the intensive collisions of the plume spices result in formation of nanoparticles and aggregates by condensation close to the target. The produced nanoagregates are deposited on a quartz substrate where grow in a specific nanostructure. Diagnostics of the laser-generated plasma for the laser fluences used in this study is performed. Study based on change of ambient conditions shows that the increase of the air pressure from 10 Torr to atmospheric one leads to transition from thin film to porous structures. It is found that the surface morphology of the structures produced by pulsed laser deposition (PLD) in open air strongly depends on the substrate-target distance. The electrical properties of the obtained structures are studied by measurement of their electrical resistance. It is found that the conductivity of the structures strongly depends on their morphology. The fabricated structures have potential for application in the field of electronics and sensors.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128493394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Evgenieva, N. Kolev, P. Savov, P. Kaleyna, D. Petkov, Ventsislav Danchovski, D. Ivanov, E. Donev
A study of the atmospheric boundary layer (ABL) height and its relation to the variations in the aerosol optical depth (AOD), Ångström coefficients, water vapor column (WVC) and total ozone column (TOC) was carried out in June 2011 and June 2012 at three sites in the city of Sofia (Institute of Electronics, Astronomical Observatory in the Borisova Gradina Park and National Institute of Geophysics, Geodesy and Geography). A ceilometer CHM15k, a sun photometer Microtops II, an ozonometer Microtops II and an automatic meteorological station were used during the experiments. Measurements of the AOD, WVC and TOC were done during the development of the ABL (followed by the ceilometer). In order to access microphysical properties of the aerosols, the Ångström coefficients α and β were retrieved from the spectral AOD data by the Volz method from three wavelength pairs 500/1020nm, 500/675nm and 380/1020nm. Comparison was done between the results obtained. Daily behavior of the AOD, Ångström exponent α and turbidity coefficient β, WVC and TOC are presented. Different types of AOD and WVC behavior were observed. The AOD had maximum values 1-2 h before ABL to reach its maximum height for the day. No significant correlation is found between TOC daily behavior and that of the AOD and WVC.
{"title":"Case study of the ABL height and optical parameters of the atmospheric aerosols over Sofia","authors":"T. Evgenieva, N. Kolev, P. Savov, P. Kaleyna, D. Petkov, Ventsislav Danchovski, D. Ivanov, E. Donev","doi":"10.1117/12.2262587","DOIUrl":"https://doi.org/10.1117/12.2262587","url":null,"abstract":"A study of the atmospheric boundary layer (ABL) height and its relation to the variations in the aerosol optical depth (AOD), Ångström coefficients, water vapor column (WVC) and total ozone column (TOC) was carried out in June 2011 and June 2012 at three sites in the city of Sofia (Institute of Electronics, Astronomical Observatory in the Borisova Gradina Park and National Institute of Geophysics, Geodesy and Geography). A ceilometer CHM15k, a sun photometer Microtops II, an ozonometer Microtops II and an automatic meteorological station were used during the experiments. Measurements of the AOD, WVC and TOC were done during the development of the ABL (followed by the ceilometer). In order to access microphysical properties of the aerosols, the Ångström coefficients α and β were retrieved from the spectral AOD data by the Volz method from three wavelength pairs 500/1020nm, 500/675nm and 380/1020nm. Comparison was done between the results obtained. Daily behavior of the AOD, Ångström exponent α and turbidity coefficient β, WVC and TOC are presented. Different types of AOD and WVC behavior were observed. The AOD had maximum values 1-2 h before ABL to reach its maximum height for the day. No significant correlation is found between TOC daily behavior and that of the AOD and WVC.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116575981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Nazarova, L. Nedelchev, D. Ivanov, B. Blagoeva, N. Berberova, E. Stoykova, G. Mateev, D. Kostadinova
Azopolymers are well known organic materials for polarization holographic recording due to the induced anisotropy under illumination with polarized light. They possess all the desirable characteristics of the known polarization-sensitive materials, as high sensitivity and reversibility, but excel them substantially in the magnitude of the photoinduced birefringence. This makes possible to record reversible polarization gratings with high diffraction efficiency. In this paper results of experimental investigations on the reversibility properties of birefringence photoinduced in azopolymers are reported, depending on the conditions of subsequent optical and thermal treatment. Thin films of different polymers were prepared in order to examine the kinetics of multiple recording and erasure of birefringence in different types of azopolymers. The reversibility of the polarization recording has been studied using two different method of erasure – by increased temperature and on illumination with circularly polarized light.
{"title":"Laser induced optically and thermally reversible birefringence in azopolymers","authors":"D. Nazarova, L. Nedelchev, D. Ivanov, B. Blagoeva, N. Berberova, E. Stoykova, G. Mateev, D. Kostadinova","doi":"10.1117/12.2262357","DOIUrl":"https://doi.org/10.1117/12.2262357","url":null,"abstract":"Azopolymers are well known organic materials for polarization holographic recording due to the induced anisotropy under illumination with polarized light. They possess all the desirable characteristics of the known polarization-sensitive materials, as high sensitivity and reversibility, but excel them substantially in the magnitude of the photoinduced birefringence. This makes possible to record reversible polarization gratings with high diffraction efficiency. In this paper results of experimental investigations on the reversibility properties of birefringence photoinduced in azopolymers are reported, depending on the conditions of subsequent optical and thermal treatment. Thin films of different polymers were prepared in order to examine the kinetics of multiple recording and erasure of birefringence in different types of azopolymers. The reversibility of the polarization recording has been studied using two different method of erasure – by increased temperature and on illumination with circularly polarized light.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125105087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The spectral range of 0.85 - 0.9μm wavelengths utilized by laser diode (LD) technology contains a relatively intensive spectrum of third rovibrational overtone of the water molecule, pure of interfering spectra of the other major atmospheric gases. We developed a spectroscopic application of pulsed 100W LDs generally limited by their broad, multimode laser line. In fact, their powerful laser radiation propagating in the atmosphere is modulated significantly by multiple resonance absorption lines. The magnitude of the integral absorption pattern is assessed combining theoretical and experimental calibration and using HITRAN database. The resultant absorption spectrum is found to be unsaturated, providing a great dynamic range of measurement of atmospheric humidity within 15% random error of lidar returns ranging to 2km. The reported DIAL technique which utilizes the advantage of direct detection of the lidar profiles and simple operation is prospective for the framework of atmospheric and climatic monitoring.
{"title":"A compact DIAL hygrometer employing paired powerful laser diodes of 0.85–0.9μm wavelengths","authors":"S. Penchev, V. Pencheva, S. Naboko","doi":"10.1117/12.2262567","DOIUrl":"https://doi.org/10.1117/12.2262567","url":null,"abstract":"The spectral range of 0.85 - 0.9μm wavelengths utilized by laser diode (LD) technology contains a relatively intensive spectrum of third rovibrational overtone of the water molecule, pure of interfering spectra of the other major atmospheric gases. We developed a spectroscopic application of pulsed 100W LDs generally limited by their broad, multimode laser line. In fact, their powerful laser radiation propagating in the atmosphere is modulated significantly by multiple resonance absorption lines. The magnitude of the integral absorption pattern is assessed combining theoretical and experimental calibration and using HITRAN database. The resultant absorption spectrum is found to be unsaturated, providing a great dynamic range of measurement of atmospheric humidity within 15% random error of lidar returns ranging to 2km. The reported DIAL technique which utilizes the advantage of direct detection of the lidar profiles and simple operation is prospective for the framework of atmospheric and climatic monitoring.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131259492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Atanassova, I. Kostadinov, P. Zahariev, M. Grozeva, I. Miloushev
In present days graffiti is a common problem that many restorers have to deal with due to both its unaesthetic appearance and damaging nature for the surface beneath. We report laser cleaning of graffiti paints (black, white, blue, green and red) on limestone and granite. The efficiency of two laser systems is compared: high repetition rate (20 kHz) Copper Bromide Vapor Laser (CuBrVL) generating wavelength 510.6 nm and low repetition rate (up to 10 Hz) Q-switched Nd:YAG laser generating fundamental wavelength 1064 nm and its second harmonic 532 nm. The surface condition of the stone samples before and after cleaning is evaluated by means of optical microscopy. On that base, suitable working parameters are chosen in order to avoid under- or over-cleaning.
{"title":"Laser cleaning of graffiti on stone","authors":"V. Atanassova, I. Kostadinov, P. Zahariev, M. Grozeva, I. Miloushev","doi":"10.1117/12.2262668","DOIUrl":"https://doi.org/10.1117/12.2262668","url":null,"abstract":"In present days graffiti is a common problem that many restorers have to deal with due to both its unaesthetic appearance and damaging nature for the surface beneath. We report laser cleaning of graffiti paints (black, white, blue, green and red) on limestone and granite. The efficiency of two laser systems is compared: high repetition rate (20 kHz) Copper Bromide Vapor Laser (CuBrVL) generating wavelength 510.6 nm and low repetition rate (up to 10 Hz) Q-switched Nd:YAG laser generating fundamental wavelength 1064 nm and its second harmonic 532 nm. The surface condition of the stone samples before and after cleaning is evaluated by means of optical microscopy. On that base, suitable working parameters are chosen in order to avoid under- or over-cleaning.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115139774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Sawczak, Marcin Zyskowski, J. Karczewski, P. Atanasov, N. Nedyalkov, R. Nikov, N. Stankova, G. Śliwiński
Recently, an intensive research is carried out on plasmonic structures due to their potential application in many areas such as sensing, light harvesting and energy conversion and storage. In particular, a growing interest is observed in the Nanoparticle Over Mirror (NOM) structures for which the lithography and surface chemical functionalization represent the most popular production routes1. However, the application of those techniques is limited by the low efficacy, process complexity and chemical contamination of nanoparticles (NP). In this work, we report the contamination-free and low cost fabrication method of NOMs based on wet coating and ultrasonic-assisted nanocolloid drying process. The glass plates covered with magnetron sputtered 100 nm thick Au film and subsequently with Al2O3 layers (6 – 36 nm) by means of pulsed laser deposition are used as substrates. Au NPs are produced in the form of colloidal suspension by means of laser ablation in water using the 1064 nm, 6 ns Nd:YAG laser. The NOM synthesis is finalized by imposing of the Au NP suspension onto the as prepared Au-Al2O3/glass substrates and dried. To avoid NP agglomeration, the wet coated substrates are sonicated using 20W, 20 kHz ultrasound generator. SEM inspection of the obtained NOM structures confirms the positive sonication effect, i.e. the presence of agglomerate-free, homogenous layers. These consist of NPs (36 nm average diameter) which are characterized by the resonance absorption band at 528 nm. For NOM structures the UV-vis spectra reveal increased infrared activity and peak shift in agreement with theoretical modeling2. The NOM structure characterization is completed by analysis of the SEM and profilometry measurement results.
{"title":"Nanoparticle Over Mirror plasmonic structures prepared with use of Au colloid produced by laser ablation in water","authors":"M. Sawczak, Marcin Zyskowski, J. Karczewski, P. Atanasov, N. Nedyalkov, R. Nikov, N. Stankova, G. Śliwiński","doi":"10.1117/12.2261918","DOIUrl":"https://doi.org/10.1117/12.2261918","url":null,"abstract":"Recently, an intensive research is carried out on plasmonic structures due to their potential application in many areas such as sensing, light harvesting and energy conversion and storage. In particular, a growing interest is observed in the Nanoparticle Over Mirror (NOM) structures for which the lithography and surface chemical functionalization represent the most popular production routes1. However, the application of those techniques is limited by the low efficacy, process complexity and chemical contamination of nanoparticles (NP). In this work, we report the contamination-free and low cost fabrication method of NOMs based on wet coating and ultrasonic-assisted nanocolloid drying process. The glass plates covered with magnetron sputtered 100 nm thick Au film and subsequently with Al2O3 layers (6 – 36 nm) by means of pulsed laser deposition are used as substrates. Au NPs are produced in the form of colloidal suspension by means of laser ablation in water using the 1064 nm, 6 ns Nd:YAG laser. The NOM synthesis is finalized by imposing of the Au NP suspension onto the as prepared Au-Al2O3/glass substrates and dried. To avoid NP agglomeration, the wet coated substrates are sonicated using 20W, 20 kHz ultrasound generator. SEM inspection of the obtained NOM structures confirms the positive sonication effect, i.e. the presence of agglomerate-free, homogenous layers. These consist of NPs (36 nm average diameter) which are characterized by the resonance absorption band at 528 nm. For NOM structures the UV-vis spectra reveal increased infrared activity and peak shift in agreement with theoretical modeling2. The NOM structure characterization is completed by analysis of the SEM and profilometry measurement results.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125198240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Koleva, N. Nedyalkov, N. Fukata, W. Jevasuwan, S. Amoruso
The experimental and theoretical investigations of the optical characteristics of laser nanostructured Ag nanoparticles (AgNPs) in ZnO medium are of particular interest for this study. The Ag-ZnO nanocomposites are fabricated by room temperature pulsed laser synthesis method. Ag nanoparticles are prepared by laser deposition and subsequent laser annealing of silver thin film. Laser annealing of silver layer is performed at second and third harmonics of the Nd:YAG laser. The morphology of AgNPs differs significantly after the UV and VIS surface modification. The morphology and optical properties of the samples are studied according to the annealing regimes. A comparative study of the measured plasmon resonance properties with the theoretical calculations of the extinction efficiency by generalized multiparticle Mie (GMM) method is carried out. The extinction spectrum is determined as a function of the nanoparticles size distribution and the surrounding ZnO medium. The electromagnetic field intensity enhancement realized in the “hot spots” of AgNPs leads to substantial enhancement of the near band-edge UV photoluminescence (PL) emission of ZnO nanostructures and attenuation of the defect-related deep-level VIS PL signal after annealing at 355 nm and 532 nm.
{"title":"Laser nanostructuring for plasmon enhancement of Ag/ZnO optical characteristics","authors":"M. Koleva, N. Nedyalkov, N. Fukata, W. Jevasuwan, S. Amoruso","doi":"10.1117/12.2262097","DOIUrl":"https://doi.org/10.1117/12.2262097","url":null,"abstract":"The experimental and theoretical investigations of the optical characteristics of laser nanostructured Ag nanoparticles (AgNPs) in ZnO medium are of particular interest for this study. The Ag-ZnO nanocomposites are fabricated by room temperature pulsed laser synthesis method. Ag nanoparticles are prepared by laser deposition and subsequent laser annealing of silver thin film. Laser annealing of silver layer is performed at second and third harmonics of the Nd:YAG laser. The morphology of AgNPs differs significantly after the UV and VIS surface modification. The morphology and optical properties of the samples are studied according to the annealing regimes. A comparative study of the measured plasmon resonance properties with the theoretical calculations of the extinction efficiency by generalized multiparticle Mie (GMM) method is carried out. The extinction spectrum is determined as a function of the nanoparticles size distribution and the surrounding ZnO medium. The electromagnetic field intensity enhancement realized in the “hot spots” of AgNPs leads to substantial enhancement of the near band-edge UV photoluminescence (PL) emission of ZnO nanostructures and attenuation of the defect-related deep-level VIS PL signal after annealing at 355 nm and 532 nm.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128390157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Malcheva, K. Blagoev, M. Grozeva, V. Tankova, V. Steflekova, Stefan Alexandrov, T. Hristova, Georgi Ivanov, G. Nekhrizov
In the present work, we report on the analysis of archaeological metal artefacts from Late Bronze Age, performed by means of Laser Induced Breakdown Spectroscopy (LIBS). The experiment was carried out at ambient air and at 1064 nm of a Nd:YAG laser with pulse durations of 10 ns and energy of 10 mJ. The analytical information obtained by LIBS spectra was used for qualitative determination of the elements in the material used for manufacturing of the investigated objects. Quantitative estimation of the elemental concentration of tin and lead in the bulk of the samples was done after generating calibration curves for a set of four standard samples with a wide range of tin and lead concentrations and with similar matrix composition. The preliminary results of the qualitative and the quantitative analyses gave indications about the manufacturing process of the investigated objects and for their provenance as well.
{"title":"Qualitative and quantitative laser-induced breakdown spectroscopy analysis of archaeological metal artefacts","authors":"G. Malcheva, K. Blagoev, M. Grozeva, V. Tankova, V. Steflekova, Stefan Alexandrov, T. Hristova, Georgi Ivanov, G. Nekhrizov","doi":"10.1117/12.2262447","DOIUrl":"https://doi.org/10.1117/12.2262447","url":null,"abstract":"In the present work, we report on the analysis of archaeological metal artefacts from Late Bronze Age, performed by means of Laser Induced Breakdown Spectroscopy (LIBS). The experiment was carried out at ambient air and at 1064 nm of a Nd:YAG laser with pulse durations of 10 ns and energy of 10 mJ. The analytical information obtained by LIBS spectra was used for qualitative determination of the elements in the material used for manufacturing of the investigated objects. Quantitative estimation of the elemental concentration of tin and lead in the bulk of the samples was done after generating calibration curves for a set of four standard samples with a wide range of tin and lead concentrations and with similar matrix composition. The preliminary results of the qualitative and the quantitative analyses gave indications about the manufacturing process of the investigated objects and for their provenance as well.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125048100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Gurdev, T. Dreischuh, O. Vankov, E. Toncheva, L. Avramov, D. Stoyanov
Experimental measurements and theoretical description have been performed of the spatial intensity distribution of the backward radiative response of tissue-like Intralipid-20% dilutions in distilled water irradiated by a collimated near-infrared cw laser beam. The investigations performed are a first step toward a complete estimation of the feasibility and potentialities of a stationary one-sided linear-strategy biomedical tomography approach to detecting characteristic inclusions (inhomogeneities, say ill places) in homogeneous highly-scattering host media (healthy tissues). The experimental results obtained are in good agreement with the derived theoretical expressions that thus would be of importance for the development and numerical modeling of stationary tomography algorithms ensuring optimally accurate data processing and interpretation.
{"title":"Spatial intensity distribution of the radiative return from scattering media irradiated by a cw laser beam","authors":"L. Gurdev, T. Dreischuh, O. Vankov, E. Toncheva, L. Avramov, D. Stoyanov","doi":"10.1117/12.2261412","DOIUrl":"https://doi.org/10.1117/12.2261412","url":null,"abstract":"Experimental measurements and theoretical description have been performed of the spatial intensity distribution of the backward radiative response of tissue-like Intralipid-20% dilutions in distilled water irradiated by a collimated near-infrared cw laser beam. The investigations performed are a first step toward a complete estimation of the feasibility and potentialities of a stationary one-sided linear-strategy biomedical tomography approach to detecting characteristic inclusions (inhomogeneities, say ill places) in homogeneous highly-scattering host media (healthy tissues). The experimental results obtained are in good agreement with the derived theoretical expressions that thus would be of importance for the development and numerical modeling of stationary tomography algorithms ensuring optimally accurate data processing and interpretation.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"41 16","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120887539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Presented are results of lidar measurements and characterization of wildfire caused smoke aerosols observed in the atmosphere above the city of Sofia, Bulgaria, related to two local wildfires raging in forest areas near the city. A lidar systems based on a frequency-doubled Nd:YAG laser operated at 532 nm and 1064 nm is used in the smoke aerosol observations. It belongs to the Sofia LIDAR Station (at Laser Radars Laboratory, Institute of Electronics, Bulgarian Academy of Sciences), being a part of the European Aerosol Lidar Network. Optical, dynamical, microphysical, and geometrical properties and parameters of the observed smoke aerosol particles and layers are displayed and analyzed, such as: range/height-resolved profiles of the aerosol backscatter coefficient; integral aerosol backscattering; sets of colormaps displaying time series of the height distribution of the aerosol density; topologic, geometric, and volumetric properties of the smoke aerosol layers; time-averaged height profiles of backscatter-related Ǻngström exponent (BAE). Obtained results of retrieving and profiling smoke aerosols are commented in their relations to available meteorological and air-mass-transport forecasting and modelling data.
{"title":"Lidar measurements of wildfire smoke aerosols in the atmosphere above Sofia, Bulgaria","authors":"Z. Peshev, A. Deleva, T. Dreischuh, D. Stoyanov","doi":"10.1117/12.2263103","DOIUrl":"https://doi.org/10.1117/12.2263103","url":null,"abstract":"Presented are results of lidar measurements and characterization of wildfire caused smoke aerosols observed in the atmosphere above the city of Sofia, Bulgaria, related to two local wildfires raging in forest areas near the city. A lidar systems based on a frequency-doubled Nd:YAG laser operated at 532 nm and 1064 nm is used in the smoke aerosol observations. It belongs to the Sofia LIDAR Station (at Laser Radars Laboratory, Institute of Electronics, Bulgarian Academy of Sciences), being a part of the European Aerosol Lidar Network. Optical, dynamical, microphysical, and geometrical properties and parameters of the observed smoke aerosol particles and layers are displayed and analyzed, such as: range/height-resolved profiles of the aerosol backscatter coefficient; integral aerosol backscattering; sets of colormaps displaying time series of the height distribution of the aerosol density; topologic, geometric, and volumetric properties of the smoke aerosol layers; time-averaged height profiles of backscatter-related Ǻngström exponent (BAE). Obtained results of retrieving and profiling smoke aerosols are commented in their relations to available meteorological and air-mass-transport forecasting and modelling data.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126812755","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：