Direct inverse deformation field approach to pelvic-area symmetric image registration

This paper presents a novel technique for a consistent symmetric deformable image registration based on an accurate method for a direct inversion of a large motion model deformation field. The proposed image registration algorithm maintains one-to-one mapping between registered images by symmetrically warping them to another image. This makes the final estimation of forward and backward deformation fields anatomically plausible and applicable to adaptive prostate radiotherapy. The quantitative validation of the method is performed on magnetic resonance data obtained for pelvis area. The experiments demonstrate the improved robustness in terms of inverse consistency error and estimation accuracy of prostate position in comparison to the previously proposed methods

A Fully Parameterized Fem Model for Electromagnetic Optimization of an RF Mems Wafer Level Package

In this work, we present a fully parameterized capped transmission line model for electromagnetic optimization of a wafer level package (WLP) for RF MEMS applications using the Ansoft HFSS-TM electromagnetic simulator. All the degrees of freedom (DoF's) in the package fabrication can be modified within the model in order to optimize for losses and mismatch (capacitive and inductive couplings) introduced by the cap affecting the MEMS RF behaviour. Ansoft HFSS-TM was also validated for the simulation of capped RF MEMS devices by comparison against experimental data. A test run of capped 50 transmission lines and shorts was fabricated and tested.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

Parasitic Effects Reduction for Wafer-Level Packaging of RF-Mems

In RF-MEMS packaging, next to the protection of movable structures, optimization of package electrical performance plays a very important role. In this work, a wafer-level packaging process has been investigated and optimized in order to minimize electrical parasitic effects. The RF-MEMS package concept used is based on a wafer-level bonding of a capping silicon substrate to an RF-MEMS wafer. The capping silicon substrate resistivity, substrate thickness and the geometry of through-substrate electrical interconnect vias have been optimized using finite-element electromagnetic simulations (Ansoft HFSS). Test structures for electrical characterization have been designed and after their fabrication, measurement results will be compared with simulations.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Bulk-micromachined tunable fabry–perot microinterferometer for the visible spectral range

The design, fabrication and measured characteristics of a bulk-micromachined tunable Fabry–Perot microinterferometer (FPMI) for the visible spectral range are presented. The FPMI is formed by two parallel 40 nm thick silver mirrors supported by a 300 nm low tensile stress silicon nitride membrane with a square aperture (side length of 2 mm) and initial cavity gap of 1.2 µm. One of the mirrors is fixed, the other is under tension on a movable Si frame, which is electrostatically deflected, using several distributed electrodes, to control cavity spacing and mirror parallelism. Performance achieved is: high flatness of the mirrors (λ/10 for the visible part of the spectrum), low control voltages (<21 V for 450 nm deflection) and simple fabrication.Fundação para a Ciência e Tecnologia (FCT

Micromachined fabry-perot optical filters

The design, fabrication and measured characteristics of micromachined Fabry- Perot (F-P) optical filters for the visible spectral range are presented. Silver films of 40-50 nm thickness, evaporated on a 300 nm thick low-stress silicon nitride membrane, are used as high-quality mirrors. Two parallel mirrors, with a square aperture of up to 2x2 mm2 and initial cavity gap of 1.2 µm, form a tunable Fabry- Perot optical filter. One of the mirrors is fixed the other is under tension on a movable Si frame, which is electrostatically deflected to control the mirror spacing and parallelism. Results are compared with non-tunable F-P filters that are composed of an Ag/SiN/Ag or Ag/SiO2/Al layer stack. The FWHM of 40 nm (tunable filter) and 16 nm (non-tunable filter) have been achieved.STW - Project DEL 55.3733. Junta Nacional de Investigação Científica e Tecnológica - PRAXIS XXI-BD/5181/95