Manufacturing and verification of ZnS and Ge prisms for the JWST MIRI imager

The JWST Mid-Infrared Instrument (MIRI) is designed to meet the JWST science requirements for mid-IR capabilities and includes an Imager MIRIM provided by CEA (France). A double-prism assembly (DPA) allows MIRIM to perform low-resolution spectroscopy. The MIRIM DPA shall meet a number of challenging requirements in terms of optical and mechanical constraints, especially severe optical tolerances, limited envelope and very high vibration loads. The University of Cologne (Germany) and the Centre Spatial de Liege (Belgium) are responsible for design, manufacturing, integration, and testing of the prism assembly. A companion paper (Fischer et al. 2008) is presenting the science drivers and mechanical design of the DPA, while this paper is focusing on optical manufacturing and overall verification processes. The first part of this paper describes the manufacturing of Zinc-sulphide and Germanium prisms and techniques to ensure an accurate positioning of the prisms in their holder. (1) The delicate manufacturing of Ge and ZnS materials and (2) the severe specifications on the bearing and optical surfaces flatness and the tolerance on the prism optical angles make this process innovating. The specifications verification is carried out using mechanical and optical measurements; the implemented techniques are described in this paper. The second part concerns the qualification program of the double-prism assembly, including the prisms, the holder and the prisms anti-reflective coatings qualification. Both predictions and actual test results are shown.MIRI for JWS

Body Surface Mapping to Guide Atrial Fibrillation Ablation

International audienceAtrial fibrillation (AF) is the most common rhythm disorder, and is strongly associated with thromboembolic events and heart failure. Over the past decade, catheter ablation of AF has advanced considerably with progressive improvement in success rates. However, interventional treatment is still challenging, especially for persistent and long-standing persistent AF. Recently, AF analysis using a non-invasive body surface mapping technique has been shown to identify localised reentrant and focal sources, which play an important role in driving and perpetuating AF. Non-invasive mapping-guided ablation has also been reported to be effective for persistent AF. In this review, we describe new clinical insights obtained from non-invasive mapping of persistent AF to guide catheter ablation

Characterization of the Left-Sided Substrate in Arrhythmogenic Right Ventricular Cardiomyopathy

International audienceBackground: The correlates of left ventricular (LV) substrate in arrhythmogenic right ventricular (RV) cardiomyopathy are largely unknown.Methods and results: Thirty-two patients with arrhythmogenic RV cardiomyopathy (47±14 years; 6 women) were included. RV and LV dysplasia were defined from multidetector computed tomography and cardiac magnetic resonance imaging. Arrhythmias were characterized as right-sided or left-sided on 12-lead ECG recordings at baseline and during isoproterenol testing. In 14 patients, the imaging substrate was compared with voltage mapping and local abnormal ventricular activity. Imaging abnormalities were found in 32 (100%) and 21 (66%) patients on the RV and LV, respectively, intramyocardial fat on multidetector computed tomography being the most sensitive feature. LV involvement related to none of the Task Force criteria. Right-sided arrhythmias were more frequent than left-sided arrhythmias (P=0.003) although the latter were more frequent in case of LV involvement (P=0.02). The agreement between low voltage and fat on multidetector computed tomography was high on the RV when using either endocardial unipolar or epicardial bipolar data (κ=0.82 and κ=0.78, respectively) but lower on the LV (κ=0.54 for epicardial bipolar). LV local abnormal ventricular activity was found in all patients with LV involvement, and none of the others. The density of local abnormal ventricular activity within fat areas was similar between the RV and LV (P=0.57).Conclusions: LV substrate is frequent in arrhythmogenic RV cardiomyopathy, but poorly identified by current diagnostic strategies. Left-sided arrhythmias are more frequent in case of LV involvement. LV fat hosts the same density of local abnormal ventricular activity as RV fat, but is less efficiently detected by voltage mapping. These results support the need for alternative diagnostic strategies to identify LV dysplasia