Atrial fibrillation (AF), the most common type of cardiac arrythmia, has been a huge concern of public health. It affects more than 6 million people in the United States and over 33 million people worldwide. In the current standard of care, an electrogram and geometry map is generated by electroanatomic mapping (EAM) using a mapping catheter, to determine the origins of irregular heart rhythm. Followed by radiofrequency ablation (RFA) using ablation catheter, the targeted sites are ablated as lesions to change the electrical conduction pathway of abnormal electrogram, thus restoring the patients to normal sinus heart rhythm with minimally invasive procedure. However, a significant proportion of patients suffer from AF recurrences and requires repeated procedures, due to the lack of reliable methods to assess the cardiac structural substrates which are the potential maintaining mechanism of AF signals. In recent years, optical imaging modalities are developed to compensate this limitation, among which near-infrared spectroscopy (NIRS) is a catheter-based technique to enable direct, independent characterization of cardiac tissue pathology from spectrum morphology. In this thesis, we validate the capability of NIRS to generate map with repeatability and identify AF substrate to improve the efficacy of treatment. First, a near-infrared imaging spectroscopy was combined with an electromagnetic tracking modality, and the system was operated with high acquisition speed and real-time display to generate high-density map. Further, the robustness of NIRS optical parameters was assessed under blood mapping and various, large catheter-tissue contact angle, to simulate the dynamic circumstance of clinical procedures. A classification algorithm was introduced to predict lesion probability including both PBS and blood data, as well as to evaluate the mapping equivalence of blood and PBS. Next, the spatial resolution and the sampling density requirement of NIRS mapping method was characterized based on small gap, and the spectral properties of gap was assessed comparing to normal tissue and lesion by statistical analysis and machine learning. Lastly, we demonstrate the identification of human left atrial complex substrates using NIRS catheter with different source-detector-separations (SDSs), and reported the spectral features for the AF-related structures such as fibrosis and adipose. To summarize, the catheter-based NIRS technology is robust for in-vivo application and structural target localization, with the potential to enhance the recognition of underlying AF pathology and improve treatment efficacy.

Exercise-induced hypoalgesia (EIH) is the reduction in pain sensitivity following exercise. High-intensity or prolonged exercise is typically required to elicit an EIH response, but there is limited evidence suggesting that low-load resistance exercise with blood flow restriction (LL+BFR) may be able to elicit a robust EIH response. The purpose of these investigations was to assess the magnitude, duration, and proposed mechanisms of EIH following LL+BFR, LL with normobaric systemic hypoxemia, BFR only without exercise, high-load exercise, and a control intervention. The first study evaluated local and systemic pain pressure threshold and tolerance responses one-hour post-exercise. The results indicated that LL+BFR induced similar EIH responses to high-load resistance exercise 0- and 15-minutes post-exercise but only LL+BFR elicited an EIH response present 60-minutes post-exercise. The second study evaluated neuromuscular and perceptual responses, both proposed EIH mechanisms, during exercise. Similar neuromuscular responses were observed in all interventions. Participants reported higher ratings of perceived exertion during LL+BFR and high-load exercise, and higher levels of perceived pain during LL+BFR. These results suggested that despite high levels of motor unit recruitment, there were divergent EIH responses. However, increased pain during exercise may be a mediating factor of EIH after resistance exercise. The third study evaluated peripheral and central cardiovascular responses, which have also been hypothesized to mediate EIH. LL+BFR resulted in greater increases in systolic blood pressure during the first set of exercise, and diastolic blood pressure during all sets of exercise. LL+BFR and BFR only attenuated changes in heart rate variability (HRV). LL+BFR induced the largest increase in deoxyhemoglobin and total hemoglobin and lowered tissue saturation index. BFR only progressively increased oxyhemoglobin and total hemoglobin levels. The local and systemic cardiovascular responses suggested that prolonged EIH following LL+BFR could be related to increased central or peripheral cardiovascular stress.

Yes / A transflectance near infra red (NIR) spectroscopy approach has been used to simultaneously measure drug and plasticiser content of polymer melts with varying opacity during hot melt extrusion. A high temperature reflectance NIR probe was mounted in the extruder die directly opposed to a highly reflective surface. Carbamazepine (CBZ) was used as a model drug, with polyvinyl pyrollidone-vinyl acetate co-polymer (PVP-VA) as a matrix and polyethylene glycol (PEG) as a plasticiser. The opacity of the molten extrudate varied from transparent at low CBZ loading to opaque at high CBZ loading. Particulate amorphous API and voids formed around these particles were found to cause the opacity. The extrusion process was monitored in real time using transflectance NIR; calibration and validation runs were performed using a wide range of drug and plasticiser loadings. Once calibrated, the technique was used to simultaneously track drug and plasticiser content during applied step changes in feedstock material. Rheological and thermal characterisations were used to help understand the morphology of extruded material. The study has shown that it is possible to use a single NIR spectroscopy technique to monitor opaque and transparent melts during HME, and to simultaneously monitor two distinct components within a formulation.

Die intratracheale Applikation von Perfluorcarbonen (PFC) in ungeschädigte Lungen, z.B. als Röntgenkontrastmittel und zur PFC-induzierten cerebralen Kühlung, wird derzeit diskutiert. Ob es aufgrund der Dichte und Sauerstofflöslichkeit der PFC zu einer Beeinflussung der cerebralen Oxygenierung und Hämodynamik durch die pulmonale PFC Applikation kommt, ist bisher unbekannt. Änderungen der Konzentration von cerebralem oxygeniertem und totalem Hb koennen mittels Near-infrared Spectroscopy gemessen werden. I.) Effekt durch die PFC-Applikation in gesunde Lungen neugeborener Ferkel: Es wurden zwei verschiedene Applikationsgeschwindigkeiten (30 ml PFC pro kg Körpergewicht als Bolusgabe versus 1,5 ml/min pro kg) und zwei Füllvolumen (30 versus 10 ml/kg) verglichen. Die Bolusgabe bewirkt einen sofortigen Abfall des PaO2 und der cerebralen Oxygenierung, bei langsamer Gabe des gleichen Volumens ist dies weniger ausgeprägt. Mit 10 ml/kg PFC fand sich nahezu keine Beeinflussung der Parameter. II.) Effekte der Änderung der FiO2 in PFC-gefüllten Lungen: Hierfür wurden Änderungen der FiO2 unter konventioneller Druckbeatmung vor PFC-Applikation und unter PFC-Füllung (30 oder 10 ml/kg PFC) verglichen. Beide PFC-Volumen (mit FiO2 1,0) bedingten PaO2-Werte wie unter CMV mit FiO2 von 0,5. Mit 30 ml/kg PFC kam es unter FiO2 von 0,5 zur Abnahme des cerebralen oxygenierten Hb. Zusammenfassend ergibt sich, dass die Applikation von 10 ml PFC/kg bevorzugt werden sollte. Bei kompletter Füllung der Lungen werden durch langsame Applikation cerebrale Nebenwirkungen minimiert. In PFC-gefüllten gesunden Lungen ist zum Erhalt der systemischen und cerebralen Oxygenierung die FiO2 zu erhöhen. / Intratracheal administration of perfluorochemicals (PFC) has been suggested for reasons other than respiratory insufficiency, such as pulmonary imaging and PFC-associated brain cooling. Due to their high density and oxygen solubility, PFC application has been described to affect systemic hemodynamics and oxygenation during liquid ventilation. Whether the PFC application into healthy lungs or changes in inspired oxygen fraction (FiO2) in PFC-filled healthy lungs affects cerebral hemodynamics is not known. Changes in the concentration of cerebral oxygenated and total Hb can be measured by near-infrared spectroscopy (NIRS). I.) Initial effects of PFC application into healthy lungs of newborn piglets: Two different filling modes (rapid versus slow) and two different filling volumes (slow filling of 30 versus 10 ml PFC/kg body weight) were compared. Rapid filling caused an immediate drop of systemic and cerebrale oxygenation, which was less prominent by filling 30 ml/kg PFC slowly. Almost no changes for all parameters were found with 10 ml kg/PFC. II.) Effects of variations in FiO2 in the PFC filled lungs of healthy piglets: Changes in FiO2 during conventional mechanical ventilation (CMV) prior to PFC-application and in the PFC-filled lungs (30 ml/kg or 10 ml/kg PFC) were compared. Both PFC-volumes (at a FiO2 of 1.0) caused PaO2-values that were similar to CMV with FiO2 of 0.5. In the 30 ml/kg PFC group a reduction of cerebral oxygenated Hb was found at FiO2 of 0.5. According to the data application of 10 ml/kg PFC should be preferred. If complete filling of the lung is needed, the slow administration of PFC minimizes cerebral side effects. In PFC- filled healthy lungs an increase in FiO2 is necessary to maintain systemic and cerebral oxygenation.

Non-invasive methods to evaluate skeletal muscle oxidative capacity have beenemerging as a viable substitute for invasive methods in recent years. One ofthose methods utilises near-infrared spectroscopy (NIRS) to calculate V O2mrecovery off-kinetics following an exercise. The data analysis of the measuredsignals from the NIRS is still done manually in a time-consuming and dauntingprocess. The present thesis aimed to develop software, associated with theNIRS method, capable of analysing the recovery from a repeated arterialocclusion protocol following an exercise to assess muscle oxidative capacity.Additionally, to analyse the recovery from ischemic preconditioning as a singletest to assess muscle oxidative capacity. A method that has never been utilisedbefore.11 active, healthy subjects were analysed to calculate their recovery rate.Subjects underwent ischemic preconditioning before exercising for 6 minutesat 80% of gas exchange threshold. A repeated arterial occlusion protocol wascarried out after the exercise. A software was developed in R that utilised linearregression as well as exponential fitting to calculate the recovery rate of eachsubject during both the ischemic preconditioning and the occlusion protocol.The calculated results were compared to predetermined recovery rate results ofeach subject. The calculated results of the repeated arterial occlusion protocolgave similar results to the predetermined ones and even more data on eachsubject’s recovery from an exercise. The calculated results of the ischemicpreconditioning were promising and implied that ischemic preconditioning asa single test can be utilised as a method to assess muscle oxidative capacity.However, further research is required to confirm it. / Icke-invasiva metoder för att utvärdera skelettmuskulaturens oxidativa förmågahar på senare år blivit en användbar ersättning för invasiva metoder. Nearinfrared spectroscopy (NIRS) är en utav dessa metoder och har använts föratt beräkna V O2m återhämtning off-kinetics efter träning. Dataanalysen av deuppmätta signalerna från NIRS görs fortfarande manuellt i en tidskrävandeoch felbenägen process. Syftet med den här uppsatsen var att utveckla enprogramvara som kopplad till NIRS metoden, kan analysera återhämtningenfrån ett protokoll med upprepade arteriella ocklusioner efter träning för attutvärdera skelettmuskulaturens oxidativa förmåga. Dessutom att analyseraåterhämtningen från ischemic preconditioning som ett enda test för att utvärderaskelettmuskulaturens oxidativa förmåga. En metod som aldrig tidigare använts.11 aktiva, friska försökspersoner analyserades för att beräkna deras återhämtningshastighet.Försökspersonerna genomgick ischemic preconditioning innan de tränadei 6 minuter med 80% av gasutbyteströskeln. Ett protokoll med upprepadearteriella ocklusioner genomfördes efter träningen. En programvara utveckladesi R som använde sig av linjär regression och monoexponentiell funktionsanpassningför att beräkna återhämtningshastigheten för varje försöksperson under bådeichemic preconditioning och ocklusionprotokollet. De beräknade resultatenjämfördes med förutbestämda resultat av återhämtningshastigheten för varjeförsöksperson. De beräknade resultaten av ocklusionprotokollet gav liknanderesultat som de förutbestämda och gav ännu fler uppgifter om varje försökspersonåterhämtning efter träning. De beräknade resultaten av ischemic preconditioningvar lovande och indikerade att ischemic preconditioning som ett enda testkan användas som en metod för att utvärdera skelettmuskulaturens oxidativaförmåga. Det krävs dock ytterligare forskning för att bekräfta detta.

La digestion anaérobie est un moyen de traitement des déchets solides produisant de l'énergie sous forme de biogaz (méthane et dioxyde de carbone). L'optimisation de la production de méthane passe par une sélection des déchets à fort potentiel méthane. Actuellement, la mesure du potentiel méthane est réalisée par le test BMP (Biochemical Methane Potential), qui repose sur une fermentation pouvant durer plus de 30 jours, ce qui est trop long pour une installation industrielle. Une méthode rapide de détermination du potentiel méthane est donc nécessaire. Le BMP est lié uniquement à la quantité et à la qualité de la matière organique. Cette méthode doit donc réaliser une analyse globale et rapide de la matière organique. L'objectif de la thèse a été d'identifier et d'étudier une méthode rapide d'analyse de la matière organique de déchets solides permettent de prédire le potentiel méthane. Suite au travail bibliographique, la spectroscopie proche infrarouge s'est révélée la méthode la plus appropriée: analyse globale et rapide, non destructive, préparation d'échantillon réduite, possibilité d'utiliser des fibres optiques pour déporter la mesure. Nous avons ensuite étudié des étalonnages pour prédire le potentiel méthane d'un ensemble homogène de 74 déchets. Un coefficient de corrélation de 0,76 et un écart standard de prédiction (RMSEP) de 28 ml CH4.g-1 MV ont été obtenus. Ensuite, les coefficients du modèle ont été analysés par rapport aux molécules présentes et rapprochés des variables sélectionnées par algorithme génétique afin de valider ce modèle d'un point de vue chimique. Enfin, la robustesse de ce modèle vis à vis de l'origine des échantillons et de l'humidité a été testée. Les résultats montrent clairement le fort potentiel de la spectroscopie proche infrarouge pour la prédiction du potentiel méthane. Pour une utilisation industrielle, il ressort qu'une attention particulière doit être portée sur l'ensemble d'étalonnage, qui doit être le plus exhaustif possible. / Anaerobic digestion is a solution to process solid waste, while producing energy by biogas production (methane and carbon dioxide). Methane production could be optimized by selecting only wastes with high methane potential. Currently, the BMP (Biochemical Methane Potential) test is conducted to predict the methane potential. This test is based on a fermentation process. It is time consuming, sometimes, lasting over 30 days, which is too long from an industrial point of view. A rapid method for determining the methane potential is therefore urgently needed. The BMP value depends only on the quantity and the quality of the organic matter, so a method capable of determining the quality and quantity of organic matter is searched for. The objective of this thesis was to identify and study such a method. First, a bibliographic study led us to chose the near infrared (NIR) spectroscopy method: fast and global analysis of the organic matter, non-destructive method, few or no sample preparation, and remote monitoring by use of fiber optics. Second, a calibration for predicting the BMP of and homogenous sample set has been built based on a 74-waste sample set. A correlation coefficient of R² = 0,76 and a standard error of prediction (RMSEP = 28 ml CH4.g-1 VS). Then, the regression coefficients (called b coefficients) were analysed with regard to the molecules in the waste and were compared to the variables selected from the spectrum, in order to validate the model from a chemical point of view. Finally, the robustness of the model, regarding the waste origins and the moisture was tested with heterogeneous samples set. Results show the potential of the near infrared spectroscopy to predict the methane potential quickly, but attention must be paid on the calibration data set when an industrial implementation is dealt with..

Les naines brunes sont des astres incapables de déclencher et soutenir des réactions nucléaires dans leur cœur. En l’absence de cette source d’énergie, leur luminosité diminue avec le temps jusqu’à leur extinction complète. Leur flux aux longueurs d’onde de 0,8 à 2,35 μm est particulièrement altéré par l’humidité contenue dans l’atmosphère terrestre, ce qui complique l’étude de ces astres. Le but de la présente recherche est de vérifier si la division par un spectre d’étoile A0 est un moyen de corriger l’altération causée par l’atmosphère terrestre sur cette partie de leur spectre. Tout d’abord, des notions, pertinentes à la compréhension de ce travail, sont abordées. L’introduction présente quelques notions sur les naines brunes et sur l’atmosphère terrestre. Le deuxième chapitre concerne le traitement des données. Il traite de la calibration, de la mise en évidence du problème de non-répétabilité de la position de la fente du spectromètre SIMON ainsi que de ses causes. Il porte aussi sur l’uniformisation de la réponse des pixels et de la soustraction du ciel pour extraire les spectres. La méthode employée pour étudier l’effet de l’atmosphère terrestre sur les spectres de naines brunes y est présentée. Le troisième chapitre analyse les résultats obtenus par l’utilisation de l’étoile de référence de type A0 comme calibration pour corriger le spectre de naine brune, en assumant un même effet de l’atmosphère terrestre sur les deux types d’astres. Nous ne pouvons conclure, avec certitude, que l’absorption tellurique affecte de la même façon les deux spectres ni de quelle façon exactement ils sont affectés. Une recherche supplémentaire nécessitant de nouvelles prises de données à des masses d’air et à des taux d’humidité variés est requise. / Brown dwarfs are celestial bodies unable to sustain nuclear reactions. For this reason their luminosity declines until complete extinction. Their flux, particularly in the band between 0,8 and 2,35 μm, is absorbed by the water vapor in the terrestrial atmosphere. The goal of this research is to find a way to correct this part of their spectra affected by this effect. First, general notions needed to understand the project are exposed. The second chapter concerns the data reduction. The calibration, the problem of the position repeatability of the slit of the spectrometer SIMON and his cause are exposed. It discusses techniques to even up the pixels’ response and the substraction of the sky from the spectra. The method used to study the atmosphere effect on brown dwarf spectra is presented. The third chapter analyses the results that use the A0 reference star to correct the brown dwarf spectrum. We cannot conclude that the A0 spectrum is affected in the same way as the brown dwarf spectrum by the terrestrial atmosphere. The data from a single night do not allow a good analysis of this effect as a function of air mass and humidity level. Others missions are needed.

L'UMR ITAP d'IRSTEA à Montpellier et la société Pellenc SA souhaitent développer un système de mesure par spectrométrie visible - proche infrarouge permettant d'évaluer la qualité des olives et d'en suivre la maturité. La mesure doit être effectuée sur une seule olive et de manière non destructive. Les critères de maturité retenus pour une première phase d'étude sont les teneurs en eau et en huile. L'objectif de ces travaux est d'optimiser la mesure des critères de maturité par spectrométrie portable, en s'adaptant aux contraintes induites par l'objet d'étude et en levant des verrous imposés par la technologie retenue. En lien avec les objectifs industriels, trois questions scientifiques ont été soulevées :QS1 : Comment obtenir les valeurs de référence des critères de maturité à partir d'une seule olive ?QS2 : Comment mesurer le spectre d'une olive ? Quelle configuration optique est la plus adaptée à l'objet mesuré ? Quel volume de l'olive est interrogé lors de la mesure spectrale ? Le noyau intervient-il dans cette mesure ?QS3 : Comment étalonner la mesure spectrale ? Les modèles de prédiction sont-ils robustes au regard d'une variété non incluse dans leur étalonnage ? Comment inclure la masse du noyau dans les valeurs prédites ?Afin de répondre à ces questions, des études expérimentales et comparatives ont été menées. Pour la détermination de la teneur en huile (QS1) deux méthodes ont été évaluée, la résonance magnétique nucléaire (RMN) et l'extraction à l'hexane, lorsqu'elles sont appliquées à la pulpe d'une olive unique. L'étude sur les différentes configurations optiques (QS2) a permis de mettre en évidence l'impact de chacune sur la mesure spectrale et ainsi déterminer si l'ensemble de ces configurations proposées (transmission, réflexion diffuse avec propagation guidée de la lumière au moyen d'une sphère, réflexion diffuse avec propagation libre de la lumière et rétrodiffusion) sont envisageables pour la mesure sur une seule olive. De plus, ces travaux se sont intéressés au volume de peau et de pulpe réellement interrogé lors de la mesure spectrale par une étude de la perte de lumière transmise à travers la peau et la pulpe. Le questionnement de l'étalonnage des mesures spectrales (QS3) a consisté en une analyse fine des modèles construits mais aussi en une étude de la robustesse et des différentes méthodes envisageables pour l'améliorer (sélection de longueurs d'onde, mise à jour des modèles, correction “biais-pente”, méthode DOP). Le dernier point traité par ces travaux de thèse est la prise en compte de la masse du noyau dans les valeurs prédites et l'évaluation des différentes méthodes pour réaliser cette correction.L'ensemble des résultats obtenus au cours de cette thèse ont servi à fournir des éléments pour guider la conception d'un outil portable de mesures par spectrométrie sur olives individuelles. / ITAP Research Unit of IRSTEA and Pellenc SA company want to developa visible - near infrared spectroscopy measurement system in order to assess the quality of olives and monitor their ripeness. The measurement has to be non-destructive and performed on a single olive. The ripeness criteria selected are water and oil content. The main objective of this work is to optimize the measurement of these criteria, recorded by a portable spectrometer, by taking into account the constraints linked to the studied object and by overcoming the obstacles imposed by the technology used. In relation to the industrial objectives, three scientific questions were raised :SQ1 : How to get the reference values of the ripeness criteria from a single olive ?SQ2 : How to measure the spectrum of one olive ? Which optical configuration isbest suited for an olive ? Which volume of the olive is actually analyzed during thespectral measurement ? Does the spectrum contain information about the kernel ?SQ3 : How to calibrate the spectral measurement ? Are the prediction models robustregarding a variety not used for the calibration step ? How to include the kernel mass in the predicted values ?In order to answer those questions, experimental and comparative studies have been led. As the determination of water content is easily transposable to a single olive, only the measurement of oil content is studied (SQ1). Two existing methods nuclear magnetic resonance and hexane extraction have been characterized end evaluated when they are applied to the pulp of a single olive.The comparative study conducted on different optical configurations(SQ2) has high-lighted the impact of each configuration (transmission, diffuse reflectance with guidedpropagation of light through a sphere, diffuse reflectance with free propagation of light and interactance) on the spectral measurement. This study has also determined if all of these configurations are suitable for the whole olive measurements. Furthermore, the real volume analyzed during the spectral measurement has been investigated by studying the loss of transmitted light through the skin and the pulp.In order to answer SQ3, the present work provides optimized models for prediction ofwater content on the one hand and oil content on the other hand. The robustness study leads us to consider different methods (Model Update, Biais and Slope, DOP, wavelength selection) depending on the correction set used and therefore the finality of the future device. Concerning the introduction of kernel mass in predicted values, it has be done using various methods which are more or less destructive. The choice of one of these methods has been be determined by the technical possibilities of the device and the minimum expected accuracy of water and oil content predictions.Therefore, the results of this thesis provide some elements to guide the development of a portable spectrometer for measurements on individual olive fruits.

L’étude des propriétés fractales des séries biologiques fait l’objet d’un intérêt croissant. Néanmoins la littérature met en évidence une ambiguïté quand à l’explication causale de la présence de ces séries temporelles ne permettant pas de distinguer entre l’adaptation effective réalisée par un sujet ou ses capacités d’adaptabilité globales. La présente thèse a pour objectif de décorréler ces deux notions, notamment en liant le niveau comportemental au niveau cérébral. Notre première étude a permise de mettre en évidence que les propriétés mono-fractales pourraient refléter l’adaptabilité des sujets tandis que les propriétés multifractales seraient liées à l’adaptation effective réalisée au cours de la tâche. La seconde étude à mise en évidence une corrélation entre les propriétés multifractales et le nombre de réseaux cérébraux mis en oeuvre au cours de la tâche, reflétant l’adaptation effective aux contraintes expérimentales imposées. Les résultats de ces travaux de thèse nous ont permis de mieux comprendre la signification fonctionnelle des analyses fractales en terme d’adaptation effective et d’adaptabilité. / The study of fractal properties in biological time series is of increasing interest. Nevertheless, the literature highlights an ambiguity on the causal explanation of the presence of these time series which does not make it possible to distinguish between the effective adaptation made by a subject or his overall adaptability capacities. The aim of this dissertation is to decorrelate these two notions, notably by linking the behavioral level to the cerebral level. Our first study allowed to highlight that the mono-fractal properties could reflect the adaptability of the subjects whereas the multifractal properties would be related to the effective adaptation carried out during the task. The second study showed a correlation between the multifractal properties and the number of brain networks implemented during the task, reflecting the effective adaptation to the experimental constraints imposed. The results of this work have allowed us to better understand the functional meaning of fractal analyzes in terms of effective adaptation and adaptability.

O objetivo deste trabalho é o desenvolvimento de um laser de centro de cor para aplicações em espectroscopia. O laser opera em regime CW e a cavidade óptica utilizada é do tipo X, com dois espelhos esféricos intracavidade astigmáticamente compensados. O meio ativo utilizado foi um cristal de KCl:Li+ com centros FA (II), e como fonte de bombeamento foi empregado um laser de Ar+ em 514nm. O limiar de potência de bombeamento foi de 120 mW, a eficiência energética foi de 2,8% e o intervalo de sintonia obtido vai de 2,56 a 2,82 &#956m numa potência de bombeamento de 700mW. O laser opera também com a cavidade na configuração anel. Para testar o LCC foram feitas aplicações empregando a técnica de espectroscopia intercavidade em cristais de KCl: Li+: NO-2: NO-3 e KBr:OH-. / The present work shows the development of a color Center laser for spectroscopy application. It is a CW laser which uses an X-type cavity with two astigmatically compensated intracavity spherical mirrors. The laser can be converted to a ring laser. The used active medium was a KCl:Li+ single crystal with a FA (II) centers and the pumping source was an Ar+ laser (&#955= 514nm, 700mW). Pump power at threshold was measured to be 120mW. The tuning range was 2.56&#60 &#955 &#60 2.82 &#956m and the slope efficiency was 2,8%. To test the color center laser we measured intracavity spectra of KCl: Li+: NO-2: NO-3 and KBr:OH- single crystals.