Calibration and performances of the integrated Mach-Zehnder (iMZ) wavefront sensor for extreme adaptive optics

International audienceWe describe new results obtained with the integrated Mach-Zehnder (iMZ) self referenced wavefront sensor (WFS) allowing to extract independently phase and amplitude from intensity variations in the pupil images produced by the interferometer. This kind of wavefront sensor meets extreme adaptive optics requirements, high speed (1 kHz) and high accuracy (< 10 nm at 5-10 cm spatial scale), as well as the reconstruction of phasing errors on segmented telescopes and scintillation measurements. In this paper we present the calibration method we have developed and validated experimentally to accurately extract the phase and the amplitude of the wavefront from the Mach-Zehnder signal, using several diversities in the phase patterns. We also present a new phase modulation method which combined with an unwrapping algorithm increases the dynamical range of the wavefront sensor up to several microns, otherwise limited to ± lambda/4 without these new strategies. Numerical simulations of the Mach-Zehnder performances for various turbulence phase will be presented to address the ultimate sensor accuracy. We will also report on our latest laboratory calibration results, using a deformable mirror and a spatial light modulator to introduce the required phase modulations

Cardiologie

In 2019, the guidelines on the new entity « chronic coronary syndrome » have been published. They influence importantly the work-up and treatment of patients with stable coronary artery disease. We will also report on publications showing the benefit of percutaneous aortic valve implantation (TAVI) in patients with aortic stenosis and low risk surgical risk. With regard to infectious endocarditis, we elucidate the importance of the vegetation's size for predicting mortality and the prognostic value of the positron emission tomography in predicting septic embolism. We highlight the spectacular results of the DAPA-HF study in patients with heart failure and review publications showing the important role of the detection of myocardial fibrosis and scar by cardiac MRI for risk stratification of sudden cardiac death.L’année 2019 a été marquée par la publication de recommandations sur une nouvelle entité, appelée « syndrome coronarien chronique », qui modifient de manière importante la prise en charge et le traitement des patients avec une maladie coronarienne stable. On relève plusieurs publications démontrant, chez les patients ayant une sténose aortique, et étant à bas risque chirurgical, le bénéfice d’un traitement percutané par rapport à un traitement chirurgical. La prise en charge de l’endocardite a été challengée par deux publications montrant que la taille de la végétation est un facteur de risque de mortalité et la valeur pronostique de la tomographie par émission de positons dans la survenue d’emboles septiques. Nous discutons les résultats spectaculaires de l’étude DAPA-HF dans le domaine d’insuffisance cardiaque et plusieurs études montrant l’intérêt de la recherche de cicatrice myocardique à l’IRM cardiaque dans la stratification du risque de mort subite