Development of a Multimode Instrument for Remote Measurements of Unsaturated Soil Properties

The hydromechanical behavior of soil is governed by parameters that include the moisture content, soil matric potential, texture, and the mineralogical composition of the soil. Remote characterization of these and other key properties of the soil offers advantages over conventional in situ or laboratory-based measurements: information may be acquired rapidly over large, or inaccessible areas; samples do not need to be collected; and the measurements are non-destructive. A field-deployable, ground-based remote sensor, designated the Soil Observation Laser Absorption Spectrometer (SOLAS), was developed to infer parameters of bare soils and other natural surfaces over intermediate (100 m) and long (1,000 m) ranges. The SOLAS methodology combines hyperspectral remote sensing with differential absorption and laser ranging measurements. A transmitter propagates coherent, near-infrared light at on-line (823.20 nm) and off-line (847.00 nm) wavelengths. Backscattered light is received through a 203-mm diameter telescope aperture and is divided into two channels to enable simultaneous measurements of spectral reflectance, differential absorption, and range to the target. The spectral reflectance is measured on 2151 continuous bands that range from visible (380 nm) to shortwave infrared (2500 nm) wavelengths. A pair of photodetectors receive the laser backscatter in the 820–850 nm range. Atmospheric water vapor is inferred using a differential absorption technique in conjunction with an avalanche photodetector, while range to the target is based on a frequency-modulated, self-chirped, homodyne detection scheme. The design, fabrication, and testing of the SOLAS is described herein. The receiver was optimized for the desired backscatter measurements and assessed through a series of trials that were conducted in both indoor and outdoor settings. Spectral reflectance measurements collected at proximal range compared well with measurements collected at intermediate ranges, demonstrating the utility of the receiver. Additionally, the noise characteristics of the spectral measurements were determined across the full range of the detected wavelengths. Continued development of the SOLAS instrument will enable range-resolved and water vapor-corrected reflectance measurements over longer ranges. Anticipated applications for the SOLAS technology include rapid monitoring of earth construction projects, geohazard assessment, or ground-thruthing for current and future satellite-based multi- and hyperspectral data

Novel spectral imaging instrumentation for environmental sensing in extreme environments

Spectral imaging techniques provide a valuable means of improving our understanding of the world around us. Environmental monitoring approaches that utilise these techniques are, therefore, essential to our understanding of the effects of climate change. Hyperspectral imaging applications are of particular benefit to a broad range of environmental monitoring scenarios, providing rich datasets that combine both spectral and spatial information, enabling intricate features and variations to be visualised. However, to date, most commercially available hyperspectral instrumentation remains bulky and expensive, significantly limiting their user-base and accessibility. These factors substantially limit the use of these instruments resulting in much of our information coming from a few well-resourced research teams across a limited number of more easily accessed field locations. These limitations, have a compounded effect on the quality and robustness of hyperspectral data outputs, particularly within more extreme settings, as the comparatively small sample of more accessible locations is not necessarily representative of the much larger whole. This thesis presents on the development and testing of three novel low-cost hyperspectral imaging instruments designed specifically for environmental monitoring applications, providing valuable, low-cost alternatives to currently available commercial systems. Specifically, the three instruments presented within this thesis are: a low-cost laboratory-based hyperspectral imager, a semi-portable instrument capable of accurate data capture within a laboratory setting; the Hyperspectral Smartphone, an ultra-low-cost smartphone-based fully portable hyperspectral imager; and a low-cost high-resolution hyperspectral imager capable of resolving mm-scale spatial targets. All instruments were rigorously tested to analyse and evaluate their performances. Each instrument was shown to perform well across a range of environmental monitoring applications demonstrating that expensive commercial instrumentation is not required to achieve accurate and robust hyperspectral imaging. These low-cost instruments could promote the widespread dissemination of accessible hyperspectral imaging equipment, facilitating the democratisation of hyperspectral measurement modalities across environmental monitoring applications and beyond

Continuous feeding and mixing in continuous tablet manufacturing : measuring system responses to parameter and material changes and implementation of NIR sphere

Tese de mestrado, Engenharia Farmacêutica, Universidade de Lisboa, Faculdade de Farmácia, 2017Continuous manufacturing is an advantageous choice in many industries, including the pharmaceutical. Its main advantages are better controllability, and, for sufficiently large volumes, lower manufacturing costs by decreased footprint and labor. Since the inception of the process analytical technology initiative (PAT), and more recently, the quality-by-design (QbD) initiative, significant efforts in designing new manufacturing strategies for the pharma industry are underway. Continuous mixing is important in many processes in pharmaceutical manufacturing, including some obvious ones such as API and lubricant mixing, and some less apparent, such as wet granulation, coating, extrusion, and drying, where mixing often plays a critical role. In this study, NIR spectroscopy is used to further understand a novel continuous mixing process. This new method is used to monitor the concentration of paracetamol blends that range from 30 to 70% (w/w). An experimental design was performed to define a set of runs in order to identify the critical process parameters and evaluate their impact on the critical quality attributes such as the homogeneity of the powder blend produced in the in-line mixer. The in-line mixer used was the Hosokawa Modulomix. The mixing process was monitored by an near infrared spectral camera aided by an integration sphere with an innovative design, attached to the mixer’s outlet port. The process parameters evaluated and their respective range were: mixer speed (300-1500 rpm), total feed rate (5-15 kg/h), inlet port (A or B) and excipient type (dibasic calcium phosphate or paracetamol). All process variables were kept constant throughout the experiments, and whilst maintaining the total feed rate constant, step changes to the paracetamol concentration were introduced at different time points. These were meant to stimulate the system and allowed for monitoring of system mixing performance with alterning setpoints for a wide range of settings, and for determination of the mixer’s mean residence time. The NIR spectral camera was able to operate, through the integration sphere’s innovative design, with multi-point signal acquisition for a good representative analysis of the flowing powder. The mixer speed was revealed to be the most important critical process parameter. Mixture performance was determined via the powder blend’s relative standard deviation (RSD), and results revealed that powder homogeneity was very good under all experimental conditions, having the RSD values always remained under 5% RSD.A produção contínua tem sido frequentemente adotada em muitas indústrias, incluindo a química, alimentar, micro-electrónica, entre outras. As suas principais vantagens são um maior controlo, e para volumes suficientemente grandes, menores custos de fabrico através de menor necessidade em mão de obra e possibilidade de uso de equipamento de menores dimensões. A indústria farmacêutica contudo, devido à natureza rígida da sua estrutura regulamentar, tem permanecido focada em larga medida no método de produção por “lote”. Não obstante, desde a iniciativa de tecnologia analítica de processo lançada pela Food and Drug Administration, e mais recentemente, da iniciativa Quality-by-design, (que visam não só o desenvolvimento integrado do produto desde a sua conceção até a sua entrada no mercado mas também a otimização de recursos, matérias primas e instalações), que esforços significativos têm sido levados a cabo de forma a desenvolver novas estratégias de produção. A produção contínua de formas farmacêuticas sólidas de dose individual tem pois, como um dos seus objetivos, melhorar a qualidade do medicamento a partir da origem, reduzindo o seu custo de fabrico, e ao mesmo tempo permitir aos doentes o acesso a medicamentos mais seguros. Para isso, realizam-se delineamentos experimentais para perceber de que forma os parâmetros do processo influenciam as respostas do mesmo. As tecnologias analíticas de processo são ferramentas fundamentais de monitorização porque fornecem dados do produto e do processo em tempo real. Esses dados são utilizados em modelos de análise multivariada que por sua vez devolvem informação sobre o processo. Esses modelos são em grande medida, ferramentas que contribuem para a construção de mecanismos de controlo do próprio processo. Estes mecanismos de controlo garantem que perturbações no processo são corrigidas de forma a obter os atributos críticos de qualidade desejados conforme as especificações. A produção contínua aplicada à produção farmacêutica secundária é atrativa visto que processos como compressão, compactação por rolos, e enchimento de cápsulas já são efetuados de forma contínua, enquanto que a mistura, granulação por via húmida, secagem e revestimento são efetuados em “lote”. Esta combinação de operações “lote” com operações contínuas torna-se frequentemente uma fonte de ineficiência. Para além disso, os processos contínuos podem ser aumentados em escala simplesmente por extensão do tempo de operação, ao contrário dos processos tipo “lote”, que invariavelmente requerem um aumento de escala físico que muitas vezes não é fácil de fazer nem eficaz. A produção contínua possui outras vantagens em relação à produção por “lote”, nomeadamente o tamanho de equipamento reduzido, menor inventário para o processo, menos manuseamento sólido como por exemplo o enchimento e esvaziamento de misturadores (reduzindo assim efeitos potencialmente indesejados como a segregação), um controlo mais preciso em torno de um estado estacionário bem definido, e uma maior uniformidade na aplicação de tensões de corte. Contudo, a produção contínua tem algumas limitações, como o custo inicial mais elevado, dificuldade de implementação para produtos com baixo volume de produção, e flexibilidade reduzida do processo. Apesar da produção contínua ter sido fortemente implementada na indústria química, o conhecimento relativamente à mistura de pós por via de processos contínuos ainda é limitado e relativamente poucos artigos têm sido publicados nesta área. A mistura é uma operação unitária extremamente importante em muitos processos de produção farmacêutica, incluindo alguns bastante óbvios como a mistura de substâncias ativas e lubrificantes, e alguns menos aparentes, tais como a granulação por via húmida, revestimento, extrusão, e secagem, onde a mistura tem um papel crucial. O desenvolvimento de operações de mistura contínua requer uma avaliação de um amplo espaço paramétrico, que inclui a seleção e conceção dos equipamentos de mistura e alimentação, avaliação dos parâmetros de operação tais como velocidade de rotação das pás do misturador e taxa de alimentação, caracterização dos efeitos de propriedades físicas como distribuição do tamanho de partícula e coesão dos pós, e o controlo de variáveis ambientais tais como a temperatura e humidade relativa. Este grande número de variáveis, e as suas interações entre si, torna extremamente difícil a implementação do processo para uma nova entidade sem estudos detalhados. Tendo tudo isto em conta, a identificação de parâmetros críticos de processo é um passo essencial em direção à implementação da produção contínua. O processo de mistura em contínuo inicia-se pelo enchimento e calibração dos alimentadores que irão debitar as matérias primas em pó a serem misturadas. Estes alimentadores estão assentes em balanças extremamente sensíveis que pesam continuamente a quantidade de massa de pó existente dentro da tremonha, tendo um modo gravimétrico como principio de funcionamento. O sensor gravimétrico das balanças regula assim automaticamente o débito com que os pós são alimentados para o misturador. Com o misturador ligado as partículas de pó ao entrarem no misturador cilíndrico pela porta de alimentação sofrem agitação pelas pás fixas ao rotor que se encontra no eixo central do misturador. Estas pás podem ter várias configurações e orientações e portanto originam diversos tipos de fluxos de matéria dentro do misturador. Ao atingir a porta de descarga do misturador a mistura de pós homogénea é libertada para um recipiente ou para um transportador para a próxima operação unitária. Este trabalho experimental foi realizado utilizando a linha de produção contínua de comprimidos do PROMIS Centre, na University of Eastern Finland, School of Pharmacy, em Kuopio, na Finlândia. Neste trabalho, recorreu-se a alimentadores gravimétricos (KTron K-ML-D5-KT20) de duplo parafuso e a um misturador contínuo (Hosokawa Modulomix). O processo de mistura consistia em homogeneizar uma mistura de pós composta pelo principio ativo (paracetamol) e um excipiente (fosfato de cálcio ou celulose microcristalina). A monitorização do processo foi seguida em tempo real por um sistema de infravermelhos próximos com uma câmara espectral SPECIM e um sensor ImSpector (SPECIM, Finland). Este sistema encontra-se associado a um acessório inovador que permitiu a aquisição de seis sinais simultâneos em locais diferentes da zona de amostragem de forma a melhor representar o fluxo de pó que saia do misturador. Este acessório denominado de “esfera de integração” utiliza seis fibras óticas para recolher informação do fluxo de pó e foi desenhado especialmente para este processo. A relação entre os possíveis parâmetros de processo e os atributos de qualidade da mistura de pós foi estabelecida através de ensaios definidos de acordo com um delineamento experimental fazendo variar: a velocidade do misturador de 300 rpm a 1500 rpm; a taxa de alimentação total entre 5 kg/h e 15 kg/h; a porta de alimentação (A e B) e dois excipientes (fosfato de cálcio e celulose microcristalina). Considerou-se o desvio padrão relativo entre o teor de paracetamol nas amostras determinado com UVVis e o teor de paracetamol calculado a partir dos dados de registo dos alimentadores, como atributo de qualidade. A análise de componentes principais foi usada como método de análise exploratória dos espetros obtidos assim como para identificar medições atípicas. Todas variáveis do processo foram mantidas constantes ao longo das experiências. Apesar da taxa de alimentação total ter sido mantida constante ao longo das experiências, a taxa de alimentação do paracetamol e do excipiente foi variada sob forma de níveis de concentração (40%, 50%, 60% e 70%) . Estas variações tiveram como objetivo estimular o sistema, observar a sua resposta e monitorizar de que forma isso afetava a homogeneidade da mistura resultante nesses instantes. A câmara espectral de infravermelho próximo operou através da esfera de integração, com aquisição de sinal em múltiplos pontos de forma a obter uma análise representativa do fluxo de pós. Isto permitiu que os modelos de análise de componentes principais identificassem claramente as perturbações aos níveis de concentração das matérias primas causadas no sistema, e detetar o tempo necessário para que o processo atingisse o estado estacionário. Os modelos baseados nos espetros obtidos foram capazes de capturar as concentrações de paracetamol e excipiente ao longo do tempo. Estes resultados foram confirmados através de análise por resolução multivariada de curvas onde foi possível quantificar de forma precisa os teores de substância ativa e excipiente (no caso da celulose microcristalina) impondo os espetros dos compostos puros. Verificou-se também que após cerca de três minutos do inicio das experiências, o sistema atingia o estado estacionário. O sistema revelou óptimo desempenho de mistura, pois os valores do desvio padrão relativo revelaram ser inferiores a 5% em todas as experiências independentemente das definições do processo. Os modelos de regressão entre os parâmetros do processo e os atributos de qualidade indicaram que a velocidade do misturador era o parâmetro crítico de processo mais relevante.The experimental work was performed in PROMIS continuous tablet manufacturing line (University of Eastern Finland, School of Pharmacy, Kuopio, Finland). All the facilities, equipments, materials and support were gently provided by University of Eastern Finland

Kahden varpukasvin spektrien kaksisuuntaiset heijastussuhdetekijämittaukset

Recent studies have shown the benefits of multiangular remote sensing techniques for characterizing vegetation reflection properties. The study of spectral anisotropy of understory vegetation enables methods for improved plant species identification, and provides valuable input data for radiation scattering models of forests. This thesis presents the applied methods and results of a research effort carried out over the growing season of 2017 for the temporal spectral characterization of two of the economically most important wild berry species in Finland: lingonberry (Vaccinium vitis-idaea) and blueberry (Vaccinium myrtillus). The spectral bidirectional reflectance factor (BRF) data on lingonberry and blueberry shrub samples were collected in a multidirectional measurement geometry using the Finnish Geodetic Institute Goniospectrometer (FIGIFIGO) in laboratory conditions. Leaf reflectance and transmittance spectra on both species were collected with SpectroClip-TR spectral probe. The anisotropic characteristics were analysed in the spectral range from 400 to 2200 nm for view angle dependence (-40° to +40°), illumination angle dependence (+40°, +55°), seasonal dynamics over the growing season (2017), and for berry and flower detection. Both lingonberry and blueberry shrubs have strong backward and notable forward scattering characteristics on the principal plane. In the interspecies comparison, lingonberry is brighter into all view direction in the visible and near infrared wavelengths but darker in the short-wave infrared. Increasing the illumination zenith angle by 15° improves the spectral discrimination of the two dwarf shrub species by inducing a 12% ratio of the spectral responses. Vegetation indices that are commonly used in remote sensing of forests (NDVI, NDVI705, MSI, PSRI) show low sensitivity to the changes in the view- and illumination angles. The presence of lingonberries and lingonberry flowers is indicated as a spectral peak around 679 nm in the spectral ratio of samples with berries or flowers to samples without berries or flowers. It was shown that the analysis of spectral data on the reflectance anisotropy improves the spectral discrimination of the dwarf shrub species. The contribution of the berries on the obtained shrub spectra was shown to be notable enough to justify further studies by applying unmanned aerial vehicle (UAV) platforms. Future studies on the aerial spectral data are suggested to evaluate the potential of berry mapping in larger-scale.Viimeaikaiset tutkimukset ovat osoittaneet monisuunta-spektrometrian hyödyt kasvillisuuden heijastusominaisuuksien karakterisoinnissa kaukokartoituksessa. Aluskasvillisuuden spektrien anisotropian tutkiminen edesauttaa kehittämään menetelmiä kasvilajien tunnistamiseksi ja tarjoaa validointiaineistoa metsien sirontamalleihin. Tämä diplomityö esittää menetelmät ja tulokset Suomen kahden taloudellisesti tärkeimmän luonnonmarjoja tuottavan varpukasvin, mustikan (Vaccinium myrtillus) ja puolukan (Vaccinium vitis-idaea), spektrien temporaalisesta karakterisointikampanjasta kasvukauden 2017 yli. Kaksisuuntainen heijastussuhdetekijä spektriaineisto mitattiin mustikan ja puolukan varpunäytteistä monisuuntamittausgeometriassa FIGIFIGO (Finnish Geodetic Institute Goniospectrometer) goniospektrometrillä laboratorio-olosuhteissa. Lehtien heijastus- ja läpäisyspektrit mitattiin molemmista lajeista käyttäen SpectroClip-TR mittalaitetta. Anisotropiset ominaispiirteet analysointiin aallonpituuksien 400 - 2200 nm välillä katselukulmariippuvuudelle (-40° to +40°), valaistuskulmariippuvuudelle (+40°, +55°), vuodenajan aiheuttamille muutoksille (kasvukausi 2017) sekä marja ja kukintojen tunnistamiselle. Sekä puolukka että mustikka osoittavat voimakasta taaksepäin suuntautuvaa ja huomattavaa eteenpäin suuntautuvaa ominaissirontaa päätasossa. Lajien välisessä vertailussa puolukka on kirkkaampi kaikkiin mitattuihin katselukulmiin näkyvän valon ja lähi-infrapunan aallonpituuksilla, mutta tummempi lyhytaaltoisen infrapunan alueella. Valaistuskulman zeniitin kasvattaminen 15° parantaa lajien spektrien erotettavuutta aiheuttamalla 12 %:n eron lajien heijastusvasteisiin. Yleisesti metsän kaukokartoituksessa käytetyt kasvillisuusindeksit (NDVI, NDVI705, MSI, PSRI) osoittavat matalaa herkkyyttä katselu- ja valaistuskulman muutoksille. Näytteessä olevat puolukanmarjat ja -kukat erottuvat spektrissä piikkinä 679 nm:n kohdalla, kun tarkastellaan marjallisten ja kukallisten näytteiden suhdetta marjattomiin ja kukattomiin. Spektriaineiston heijastus-anisotropian analysoinnin näytettiin edesauttavan varpukasvien erotettavuutta. Marjojen vahva kontribuutio varpunäytteistä mitattuihin spektreihin osoitettiin niin selkeästi, että jatkotutkimuksia UAV (unmanned aerial vehicle) -alustalla voidaan pitää perusteltuina. Ilma-aluksilla kerättyä aineistoa ehdotetaan käytettävän marjojen laajemman kartoituksen potentiaalin selvittämiseksi

Development of a Cobinamide-Based Optical Sensor for Hydrogen Cyanide and Hydrogen Sulfide

In an occupational or military environment, a personal air-purifying respirator must be provided when breathing-air is contaminated by harmful dust, fumes, gases, aerosols, or vapors. Too often, a respirator user does not have enough information to know when to change his/her cartridge/canister and thus is potentially exposed to toxic gases. Currently, there is no definitive way to determine when respirators\u27 carbon beds have begun to fail. When an end-of-service-life indicator (ESLI) is incorporated into the carbon bed, it informs one, in real-time, when imminent breakthrough is occurring and to replace the cartridge/canister. ESLIs are a more reliable and safer way to determine respirator end-of-service-life. To date, there are no commercially available active ESLIs for inorganic gases.;The objective of this research is to develop an inexpensive, optical sensor for the detection of hydrogen cyanide (HCN) and hydrogen sulfide (H 2S) gas, which can be used to determine the end-of-service-life of a respirator carbon bed. The sensor relies on diffuse reflectance from a paper substrate fixed with cobinamide, a Vitamin B12 derivative. Cobinamide undergoes a metal-ligand binding interaction with HCN, whereas both a binding and reduction reaction may occur with exposure to H2S. Characteristic and different spectral shifts rapidly occurred after exposure to HCN and H 2S, implying a dual ESLI could be developed to simultaneously detect both gases. Upon increasing the relative humidity from 25 to 85%, the sensitivity was found to increase 7x for cobinamide-immobilized cellulose fiber filter paper and 50x for glass fiber filter paper upon exposure to 5.0 parts-per-million (ppm) HCN---the NIOSH recommended exposure limit for HCN. The cobinamide-immobilized paper sensor successfully detected low concentrations of HCN and H2S upon imminent breakthrough of respirator canisters and cartridges (respectively). The breakthrough curves of the cobinamide paper sensor correlated well with commercial electrochemical detectors, implying that cobinamide may be used to detect both gases at a certain location in the respirator carbon bed and inform the user to replace his or her cartridge/canister.;Additionally, a low-power, inexpensive 3-color (RGB) sensor was prototyped to actively monitor the total change in color of the cobinamide complex on paper upon HCN exposure. The photodiodes detected, in real-time, a rapid change in the red, green, and blue values of the cobinamide compound upon exposure to HCN at various concentrations and relative humidity levels. Total change in color from initial cobinamide on paper increased as a function of HCN concentration, where faster reaction kinetics were observed at higher relative humidity. Response times at all relative humidity levels were within 20 seconds for 5.0 ppm HCN exposure. The color sensor offers an economical and more quantitative approach to determining color change compared to current, subjective end-of-service-life indicators

Measurement Of Optical Properties Of Soot Using Cavity Ring-Down Spectroscopy And Integrating Nephelometry

Since black carbon and brown carbon are among the greatest contributors to radiative forcing (black carbon being second only to carbon dioxide), this work focuses on the laboratory measurement of their optical properties using cavity ring-down spectroscopy (CRDS) and integrating nephelometry. Water soluble soot is collected using an impinger and cascade impactor by burning different fuel types to mimic ambient aerosols dominant in regions where biomass burning is the main source of aerosols. Using an optical parametric oscillator (OPO) as a light source, we are able to measure extinction and scattering over a wide range of wavelengths. A correction factor is calculated using a method by Anderson and Ogren to reconcile scattering from the nephelometer to extinction from the CRDS. The extinction-minus-scattering method is then used to determine absorption. Purely scattering polystyrene latex (PSL) spheres of known sizes (100 – 700 nm) are used in the lab to calibrate the system for this study. Measurements of optical properties of soot collected from different fuel sources at different stages of burning are reported

Controlled Experiments of Hillslope Coevolution at the Biosphere 2 Landscape Evolution Observatory: Toward Prediction of Coupled Hydrological, Biogeochemical, and Ecological Change

Understanding the process interactions and feedbacks among water, porous geological media, microbes, and vascular plants is crucial for improving predictions of the response of Earth’s critical zone to future climatic conditions. However, the integrated coevolution of landscapes under change is notoriously difficult to investigate. Laboratory studies are limited in spatial and temporal scale, while field studies lack observational density and control. To bridge the gap between controlled laboratory and uncontrollable field studies, the University of Arizona built a macrocosm experiment of unprecedented scale: the Landscape Evolution Observatory (LEO). LEO comprises three replicated, heavily instrumented, hillslope-scale model landscapes within the environmentally controlled Biosphere 2 facility. The model landscapes were designed to initially be simple and purely abiotic, enabling scientists to observe each step in the landscapes’ evolution as they undergo physical, chemical, and biological changes over many years. This chapter describes the model systems and associated research facilities and illustrates how LEO allows for tracking of multiscale matter and energy fluxes at a level of detail impossible in field experiments. Initial sensor, sampler, and soil coring data are already providing insights into the tight linkages between water flow, weathering, and microbial community development. These interacting processes are anticipated to drive the model systems to increasingly complex states and will be impacted by the introduction of vascular plants and changes in climatic regimes over the years to come. By intensively monitoring the evolutionary trajectory, integrating data with mathematical models, and fostering community-wide collaborations, we envision that emergent landscape structures and functions can be linked, and significant progress can be made toward predicting the coupled hydro-biogeochemical and ecological responses to global change

Development of laser spectroscopy for scattering media applications

Laser spectroscopy for both large and small spatial scales has been developed and used in various applications ranging from remote monitoring of atmospheric mercury in Spain to investigation of oxygen contents in wood, human sinuses, fruit, and pharmaceutical solids. Historically, the lidar group in Lund has performed many differential absorption lidar (DIAL) measurements with a mobile lidar system that was first described in 1987. During the years the lidar group has focused on fluorescence imaging and mercury measurements in the troposphere. Five lidar projects are described in this thesis: fluorescence imaging measurement outside Avignon, France, a unique lidar project at a mercury mine in Almadén, Spain, a SO2 flux measurement at a paper mill in Nymölla, Sweden, and two fluorescence imaging projects related to remote monitoring of vegetation and building facades characterization. A new method to measure wind speed remotely in combination with DIAL measurements is presented in this thesis. The wind sensor technique is called videography and is based on that images of plumes are grabbed continuously and the speed is estimated by the use of image processing. A technique that makes it possible to measure a gas in solids and turbid media, non-intrusively, is presented in this thesis. The technique is called gas in scattering media absorption spectroscopy (GASMAS) and has been used since 2001. The GASMAS concept means that a traditional spectroscopy instrument, based on tunable diode lasers, is used but the gas cell or optical path is replaced by a material that strongly scatters light. Mostly, wavelength modulation spectroscopy has been utilized. Four projects using the GASMAS technique to measure gases in fruit, wood, pharmaceutical solids, and human tissue are presented. Two applications have shown a great potential so far; to be able to diagnose the health of human sinuses and gas ventilation in sinuses, and to measure gas inside pharmaceutical solids. A performance analysis of the GASMAS technique is included. This thesis also presents a technique to suppress optical noise in fiber lasers and how to construct a compact tunable diode laser spectroscopy system based on plug-in boards for a standard computer

Measuring optical absorption coefficient of pure water in UV using the integrating cavity absorption meter.

The integrating cavity absorption meter (ICAM) has been used successfully to measure the low absorption coefficient of pure water. The ICAM produces an effective total path length of several meters or even longer, although the physical size of the instrument is only several centimeters. The long effective total path length ensures a high sensitivity that enables the ICAM to measure liquid mediums with low absorption. Compared to the conventional transmission type of instruments that were used to measure the same medium with the same path length, the ICAM eliminates the effect of scattering by introducing isotropic illumination in the medium, and consequently measures the true absorption coefficient of the medium in stead of the attenuation coefficient. The original ICAM was constructed with Spectralon and used in the wavelength range from 380 nm to 700 nm. Later studies showed that Spectralon is not suitable for measurements in the UV region because of its relatively lower reflectivity in this region and, even worse, the continuously decaying reflectivity under the exposure to UV radiation. Thus, we have developed a new way to construct the ICAM utilizing the material fumed silica. The resulting ICAM has a high sensitivity even in the UV region and doesn't have the deterioration problem. The measurement results from the new ICAM are in good agreement with the existing results. The absorption coefficients of pure water at wavelengths between 250 nm and 400 nm are presented here