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English: In this master's thesis an experimental method is developed to measure diffusivity and, in the future, detect cracks with a moving laser spot, which can scan the surface of the sample and probe different regions, with the aim of obtaining experimental results of diffusivity measurements in different materials. For this purpose, the flying spot method, which is a non- destructive test, has been used. To understand how the experiment was carried out, thermography in general is first discussed and then focus on the flying spot method. After that, there is a theoretical section specific to this method to demonstrate where the equations used to calculate the diffusivity value come from. There is also a description of the equipment used, as well as its operation and limitations. Then, the results obtained are presented and discussed and the work concludes with a summary and future work in this. Castellano En este trabajo de fin de máster se desarrolla un método experimental para medir la difusividad y, en un futuro, detectar grietas con un haz móvil, que puede escanear la superficie de la muestra y sondear diferentes regiones, con el objetivo de obtener resultados experimentales de medidas de difusividad en diferentes materiales. Para ello, se ha utilizado el método flying spot, que es un ensayo no destructivo. Para entender cómo se ha llevado a cabo el experimento, se habla primero de la termografía en general y luego se centra en el método del flying spot. Después, hay una sección teórica específica de este método para demostrar de dónde proceden las ecuaciones utilizadas para calcular el valor de la difusividad térmica. También se describe el equipo utilizado, así como su funcionamiento y limitaciones. A continuación, se presentan y discuten los resultados obtenidos y el trabajo concluye con un resumen y trabajos futuros en este sentido. Euskera Master-amaierako lan honetan, difusibitatea neurtzeko eta, etorkizunean, laser-puntu mugikor batekin pitzadurak detektatzeko metodo esperimental bat garatzen da. Pitzadura horiek laginaren azalera eskaneatu eta zenbait eskualde zundatu ditzakete, hainbat materialetako difusibitate-neurrien emaitza esperimentalak lortzeko. Horretarako, flying spot metodoa erabili da, saiakuntza ez-suntsitzailea. Esperimentua nola egin den ulertzeko, lehenbizi termografiaz hitz egiten da, oro har, eta, gero, flying spotaren metodoa aztertzen da. Ondoren, metodo horren atal teoriko espezifiko bat dago, difusibitatearen balioa kalkulatzeko erabilitako ekuazioak nondik datozen frogatzeko. Erabilitako ekipoa, funtzionamendua eta mugak ere deskribatzen dira. Ondoren, lortutako emaitzak aurkeztu eta eztabaidatu dira, eta lana amaitzeko, laburpen bat egin da, eta etorkizuneko lanak egin dira.

We have obtained an analytical expression for the surface temperature of a sample that is moving at constant velocity when it is illuminated by a modulated and focused laser beam, which remains at ...

The broad acceptance of “spot scanning” or „flying spot“ excimer lasers in the last decade has enabled the domination of corneal ablative laser surgery over other refractive surgical procedures for the correction of hyperopia, hyperopic and mixed astigmatism. This review outlines the most important reasons why the ablative laser correction of hyperopia, hyperopic and mixed astigmatism for many years lagged behind that of myopia. Most of today‘s scanning laser systems, used in the LASI K and PRK procedures, can safely and effectively perform low, moderate and high hyperopic and hyperopic astigmatic corrections. The introduction of these laser platforms has also significantly improved the long term refractive stability of hyperopic treatments. In the future, further improvements in femtosecond and nanosecond technology, eye-tracker systems, and the development of new customized algorithms, such as the ray-tracing method, could additionally increase the upper limit for the safe and predictable corneal ablative laser correction of hyperopia, hyperopic and mixed astigmatism., Široka rasprostranjenost nove generacije „spot scanning“ excimer lasera, odnosno lasera s pomičnom točkastom zrakom, omogućila je u posljednjih deset godina dominaciju laserske ablacijske kirurgije rožnice u korekciji dalekovidnosti, dalekovidnog i miješanog astigmatizma nad drugim refrakcijskim kirurškim postupcima. U članku su navedeni najvažniji razlozi zbog kojih je laserska kirurgija rožnice u ispravljanju dalekovidnosti, dalekovidnog i miješanog astigmatizma niz godina zaostajala za laserskim ispravljanjem kratkovidnosti. Većina današnjih lasera temeljenih na navedenoj tehnologiji omogućuje sigurno i učinkovito ispravljanje niskih, srednjih i visokih dalekovidnosti i astigmatizama uz pomoć postupaka LASI K i PRK. Uvođenje ovih laserskih sustava također je unaprijedilo i dugoročnu stabilnost rezultata nakon tretmana. Može se očekivati da će daljnji napredak u femtosekundnoj i nanosekundnoj tehnologiji, sustavima za praćenje pokreta oka, te razvoj novih individualiziranih algoritama poput metode “ray-tracing” u budućnosti pomaknuti današnje granice sigurne i predvidljive ablacijske laserske korekcije dalekovidnosti, kao i dalekovidnog i miješanog astigmatizma.

The broad acceptance of "spot scanning" or "flying spot" excimer lasers in the last decade has enabled the domination of corneal ablative laser surgery over other refractive surgical procedures for the correction of hyperopia, hyperopic and mixed astigmatism. This review outlines the most important reasons why the ablative laser correction of hyperopia, hyperopic and mixed astigmatism for many years lagged behind that of myopia. Most of today's scanning laser systems, used in the LASI K and PRK procedures, can safely and effectively perform low, moderate and high hyperopic and hyperopic astigmatic corrections. The introduction of these laser platforms has also significantly improved the long term refractive stability of hyperopic treatments. In the future, further improvements in femtosecond and nanosecond technology, eye-tracker systems, and the development of new customized algorithms, such as the ray-tracing method, could additionally increase the upper limit for the safe and predictable corneal ablative laser correction of hyperopia, hyperopic and mixed astigmatism.

Recently, there has been substantial progress in the development of ultracompact image projection systems. This has been enabled by the availability of electrically modulated laser sources for all three elementary colors and a 2D resonant microscanning mirror as a microopto- electro-mechanical system MOEMS device for light deflection. The laser beam formed by collimator optics is directed onto the microscanning mirror. Given the movement of the mirror, the laser beam scans the entire image area. By driving the mirror and electrically modulating the intensity of the laser beam in a synchronous manner, a projection of images can be achieved. In this contribution, we present the theoretical background of the projection system as well as the latest achievements in system design. Both monochrome and full-color systems are currently available. The latter uses a separate laser bank as an RGB light source, which is coupled with a projection head. For monochrome red systems, the laser diode can be integrated into the projection head as well, whose volume can be reduced to 1575 mm. All systems have video graphics array VGA 640480 pixels resolution and operate with 8-bit color depth per pixel and 50 frames per second.

Nowadays, composite materials are widely used in the aeronautic and aerospace industries because of their high mechanical resistance. However, they have a large heterogeneity due to the fiber and matrix they are made of. In this way, for many years, the TIC team «Thermal Imaging Fields and Characterization » from TREFLE department of I2M laboratory develops methods to measure thermal in-plane properties of heterogeneous materials such as inverses (integral transforms, double singular value decomposition…) or experimental (Flash, laser diode…) methods. The recent progress made in optical control, lasers and infrared (IR) cameras enables the development of a new scanning system (based on galvanometer-mirror) which allows the easy control of a laser hot spot spatial and temporal displacements over a plane surface. The low cost of laser diodes and optical control (galvanometric mirror) systems allows to develop a laser scanning system fixed on a test bench. We can revisit the different types of thermal excitation and realize infinite spatio-temporal combinations of thermal excitations by laser method. This is one of this thesis aims. New inverse methods based on the thermal response to an instantaneous point source heating, and temperature fields separability, have been proposed. These methods allow to estimate the thermal diffusivity tensor along the main axes of anisotropy, but also out of those axes, where it is possible to estimate the anisotropy axes orientation when the heat transfer takes place out of the image axes. These methods have produced interesting results in view of their simplicity. Moreover, they made it possible to obtain in-plane thermal diffusivities maps because, compared to the other methods, they allow to obtain, locally, thermal diffusivity tensor estimations by getting a surface heat flux map using the laser optical scanner., De nos jours, les matériaux composites sont très largement utilisés dans l’industrie aéronautique et aérospatiale car ils ont de très bonnes tenues mécaniques, mais ces matériaux comportent de fortes hétérogénéités dues aux fibres et aux liants qui les constituent. Ainsi, depuis de nombreuses années, l’équipe TIFC «Thermal Imaging Fields and Characterization » du département TREFLE de l’institut I2M développe des méthodes de mesure des propriétés thermophysiques de matériaux hétérogènes dans le plan ou dans l’épaisseur. Ces méthodes sont très variées du point de vue des méthodes inverses (transformée intégrale, double décomposition en valeurs singulières, …) ou expérimentale (Flash, diode laser, …). Le faible coût des diodes lasers et des systèmes de déplacement de miroirs galvanométriques ont permis de développer un système complet de scanner optique laser, monté sur un banc de mesure. Il permet de revisiter les différents types de sollicitations thermiques et de réaliser une infinité de combinaisons spatiotemporelles d’excitations thermiques par méthode laser. Ceci est une des principales originalités de ce travail. De nouvelles méthodes inverses basées sur la réponse thermique au point source impulsionnel et sur la séparabilité des champs de température ont été proposées. Ces méthodes ont permis d’estimer le tenseur de diffusivité thermique selon les axes principaux d’anisotropie, mais aussi hors des axes du repère de l’image, où il est possible de déterminer l’orientation des axes d’anisotropie, lorsque le transfert de chaleur s’effectue hors des axes du repère de l’image. Ces méthodes ont permis d’obtenir des résultats intéressants comptetenu de leur simplicité. De plus, elles ont permis d’obtenir des cartographies de diffusivités thermiques dans le plan car, comparées aux autres méthodes, elles permettent d’obtenir des estimations du tenseur de diffusivité thermique localement grâce à l’obtention d’une cartographie de flux thermique surfacique via le scanner optique laser.