Precision short-pulse damage test station utilizing optical parametric chirped-pulse amplification

The next generation of high-energy petawatt (HEPW)-class lasers will utilize multilayer dielectric diffraction gratings for pulse compression, due to their high efficiency and high damage threshold for picosecond pulses. The peak power of HEPW lasers will be determined by the aperture and damage threshold of the final dielectric grating in the pulse compressor and final focusing optics. We have developed a short-pulse damage test station for accurate determination of the damage threshold of the optics used on future HEPW lasers. Our damage test station is based on a highly stable, high-beam-quality optical parametric chirped-pulse amplifier (OPCPA) operating at 1053 nm at a repetition rate of 10 Hz. We present the design of our OPCPA system pumped by a commercial Q-switched pump laser and the results of the full system characterization. Initial short-pulse damage experiments in the far field using our system have been performed

AMELIORATION DES PERFORMANCES DES CHAINES LASERS SOLIDES UTILISANT L'AMPLIFICATION A DERIVE DE FREQUENCE (NOUVEAUX RESEAUX DE DIFFRACTION A HAUTE TENUE AU FLUX ET MISE EN FORME PROGRAMMABLE DE FAISCEAUX LASERS PAR MODULATION DE LA PHASE SPATIALE)

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

Imagerie microscopique de champs électromagnétiques par interférométrie à décalage quadri-latéral. Applications à la biologie

Cette thèse a pour but d'étudier l'utilisation d'un analyseur de front d'onde basé sur l'interférométrie à décalage quadri-latéral pour l'imagerie microscopique en transmission. Cette technique d'interférométrie, développée initialement par la société Phasics (Palaiseau) pour les marchés de la métrologie optique et de la caractérisation de faisceaux laser essentiellement, peut aussi permettre d'obtenir la cartographie d'un champ électromagnétique complexe par mesure de front d'onde. En l'utilisant sur un microscope en condition d'imagerie, nous avons obtenu des images de l'intensité et de la différence de chemin optique introduite par un échantillon semi-transparent, définissant ainsi une nouvelle technique de contraste de phase quantitatif. Il s'agit d'un travail codirigé entre l'Institut Fresnel et l'entreprise Phasics (convention CIFRE), mené en collaboration avec le Centre d'Immunologie de Marseille Luminy. Dans cette thèse, nous discutons dans un premier temps de l'utilisation de l'analyseur en tant que détecteur placé dans le plan image d'un microscope optique classique, puis nous considérons deux modèles pour la formation des images de différence de chemin optique. Le premier modèle, dit projectif dans l'espace objet, suppose une mesure directe par l'analyseur de la différence de chemin optique locale introduite par l'échantillon. Nous montrons que cette hypothèse est valable pour deux applications particulières : la détermination de la quantité de matière sèche au sein d'un échantillon biologique, et la cartographie de la distribution de température induite par échauffement de particules d'or dans le plan objet du microscope. Le deuxième modèle prend en compte les effets de diffraction simple par l'échantillon et de filtrage par le système d'imagerie, en considérant l'angle sous lequel l'échantillon est illuminé.The aim of this thesis is the use of a quadriwave lateral shearing interferometer for transmission microscopic imaging. First developped for optical metrology and laser beam caracterisation by the Phasics company (Palaiseau), this interferometric technique gives complexe electromagnetic field cartography by wavefront sensing. Using a microscope in imaging conditions, we obtained intensity and optical path difference images introduced by a semi-transparent sample. Thereby, we defined a new quantitative phase contrast technique.This work is co-directed by the Fresnel Institute and the Phasics company (CIFRE convention), in collaboration with the Centre Immunologique de Marseille Luminy. In this thesis, first we discuss the wavefront sensor use as a sensor plugged on the classical optical microscope image plane ; then we consider two models for optical path difference image formation. The first one, named object space projection, supposes a direct measurement of the optical path difference introduced by a sample. We show that this hypothesis is valid for two particular applications : dry matter determination within a biological sample, and temperature distribution induced by gold nano-particule heating. Thesecond model takes into account the simple sample diffraction and the optical device filtering depending on the illumination angle. This second approach allows us to build a model for intensity and optical path difference image formation for any planewave illumination. So we studied the image formation from a spatially partial incoherent illumination to a complete incoherent illumination. We made electromagnetic field measurements with the wavefront sensor in this last case. Then we discuss semi-transparent tomographic reconstruction by measurements in different imaging planes.One chapter is dedicated to quantitative phase imaging in biology, in particular with mitotic index determination within a cell population.AIX-MARSEILLE3-Bib. élec. (130559903) / SudocSudocFranceF

Phase measurement of a segmented wave front using PISton and TILt interferometry (PISTIL)

International audienceNew architectures for telescopes or powerful lasers require segmented wave front metrology. This paper deals with a new interferometric wave front sensing technique called PISTIL (PISton and TILt), able to recover both piston and tilts of segment beams. The main advantages of the PISTIL technique are the absence of a reference arm and an access to the tilt information. An explanation of the principle, as well as an experimental implementation and the use of a segmented active mirror, are presented. Measurement errors of λ/200 for piston and 40 µrad for tilts have been achieved, well beyond performances requested for the above mentioned applications

Quantitative retardance imaging by means of quadri-wave lateral shearing interferometry for label-free fiber imaging in tissues

International audienc

Quantitative retardance imaging of biological samples using quadriwave lateral shearing interferometry

We describe a new technique based on the use of a high-resolution quadri-wave lateral shearing interferometer to perform quantitative linear retardance and birefringence measurements on biological samples. The system combines quantitative phase images with varying polarization excitation to create retardance images. This technique is compatible with living samples and gives information about the local retardance and structure of their anisotropic components. We applied our approach to collagen fibers leading to a birefringence value of (3.4 +/- 0.3) . 10(-3) and to living cells, showing that cytoskeleton can be imaged label-free