6 research outputs found
MOEMS deformable mirror testing in cryo for future optical instrumentation
MOEMS Deformable Mirrors (DM) are key components for next generation
instruments with innovative adaptive optics systems, in existing telescopes and
in the future ELTs. These DMs must perform at room temperature as well as in
cryogenic and vacuum environment. Ideally, the MOEMS-DMs must be designed to
operate in such environment. We present some major rules for designing /
operating DMs in cryo and vacuum. We chose to use interferometry for the full
characterization of these devices, including surface quality measurement in
static and dynamical modes, at ambient and in vacuum/cryo. Thanks to our
previous set-up developments, we placed a compact cryo-vacuum chamber designed
for reaching 10-6 mbar and 160K, in front of our custom Michelson
interferometer, able to measure performances of the DM at actuator/segment
level as well as whole mirror level, with a lateral resolution of 2{\mu}m and a
sub-nanometric z-resolution. Using this interferometric bench, we tested the
Iris AO PTT111 DM: this unique and robust design uses an array of single
crystalline silicon hexagonal mirrors with a pitch of 606{\mu}m, able to move
in tip, tilt and piston with strokes from 5 to 7{\mu}m, and tilt angle in the
range of +/-5mrad. They exhibit typically an open-loop flat surface figure as
good as <20nm rms. A specific mount including electronic and opto-mechanical
interfaces has been designed for fitting in the test chamber. Segment
deformation, mirror shaping, open-loop operation are tested at room and cryo
temperature and results are compared. The device could be operated successfully
at 160K. An additional, mainly focus-like, 500 nm deformation is measured at
160K; we were able to recover the best flat in cryo by correcting the focus and
local tip-tilts on some segments. Tests on DM with different mirror thicknesses
(25{\mu}m and 50{\mu}m) and different coatings (silver and gold) are currently
under way.Comment: 11 pages, 12 Figure
Differential associations between plasma oxylipins and cardiometabolic risk factors after DHA and EPA supplementation: the ComparED study
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Comparing the serum TAG response to high-dose supplementation of either DHA or EPA among individuals with increased cardiovascular risk: the ComparED study
Les revues en sciences de l’éducation : mutations et permanences
Les revues de sciences de l’éducation sont un support privilégié pour ce champ. Nous les abordons sous l’angle des mutations et des permanences mais aussi dans la perspective de les lire et d’y publier. Ne nous intéresser qu’aux revues animées par la volonté de « faire science » permet de les distinguer de celles qui expriment des préoccupations strictement professionnelles. Notre sous-titre précise les finalités de l’ouvrage, lire, publier, diffuser, qui ne peuvent être poursuivies que si elles s’appuient sur des écrits sélectionnés, améliorés et validés selon des critères scientifiques et si la diffusion permet d’y accéder. Or, les revues se trouvent confrontées à bien des transformations : la révolution du numérique qui entraîne une réflexion sur les supports, les contraintes économiques de plus en plus pressantes et stressantes, enfin l’omniprésence de l’évaluation. Quels choix effectuer ? Comment les argumenter et les assumer ? Comment informer sur les procédures de décision et de fabrication ? Comment maintenir un haut niveau d’exigence ? Comment aider les « jeunes chercheurs » à être publiés sans y renoncer ? Telles sont les questions dont ce livre s’empare avec le désir explicite de contribuer à l’édification d’un « collège des revues »