40 research outputs found
A magnetic liquid deformable mirror for high stroke and low order axially symmetrical aberrations
We present a new class of magnetically shaped deformable liquid mirrors made
of a magnetic liquid (ferrofluid). Deformable liquid mirrors offer advantages
with respect to deformable solid mirrors: large deformations, low costs and the
possibility of very large mirrors with added aberration control. They have some
disadvantages (e.g. slower response time). We made and tested a deformable
mirror, producing axially symmetrical wavefront aberrations by applying
electric currents to 5 concentric coils made of copper wire wound on aluminum
cylinders. Each of these coils generates a magnetic field which combines to
deform the surface of a ferrofluid to the desired shape. We have carried out
laboratory tests on a 5 cm diameter prototype mirror and demonstrated defocus
as well as Seidel and Zernike spherical aberrations having amplitudes up to 20
microns, which was the limiting measurable amplitude of our equipmentComment: To appear in Optics Expres
Wavefront correction with a ferrofluid deformable mirror: experimental results and recent developments
We present the research status of a deformable mirror made of a magnetic
liquid whose surface is actuated by a triangular array of small current
carrying coils. We demonstrate that the mirror can correct a 11 microns low
order aberrated wavefront to a residual RMS wavefront error 0.05 microns.
Recent developments show that these deformable mirrors can reach a frequency
response of several hundred hertz. A new method for linearizing the response of
these mirrors is also presented.Comment: To appear in "Ground-based and Airborne Instrumentation for Astronomy
II" SPIE conference, Marseille, 23-28 June 200
Archives et création : nouvelles perspectives sur l'archivistique. Cahier 1
Ce cahier de recherche fait état des travaux menés au cours de la première étape (2013-2014) du projet « Archives et création : nouvelles perspectives sur l’archivistique ». Il comprend les textes suivants : Yvon Lemay et Anne Klein, « Introduction », p. 4-6; Yvon Lemay, « Archives et création : nouvelles perspectives sur l’archivistique », p. 7-19; Anne-Marie Lacombe, « Exploitation des archives à des fins de création : un aperçu de la littérature », p. 20-59; Simon Côté-Lapointe, « Archives sonores et création : une pratique à la croisée des chemins », p. 60-83; Hélène Brousseau, « Fibres, archives et société », p. 84-104; Annie Lecompte-Chauvin, « Comment les archives entrent dans nos vies par le biais de la littérature », p. 105-120; Aude Bertrand, « Valeurs, usages et usagers des archives », p. 121-150; Laure Guitard, « Indexation, émotions, archives », p. 151-168; Anne Klein, Denis Lessard et Anne-Marie Lacombe, « Archives et mise en archives dans le champ culturel. Synthèse du colloque « Archives et création, regards croisés : tournant archivistique, courant artistique », p. 169-178. De plus, dans le but de situer le projet dans un contexte plus large, le cahier inclut une bibliographie des travaux effectués sur les archives et la création depuis 2007, p. 179-182.Le projet de recherche est financé par le Conseil de recherches en sciences humaines du Canada (Programme Savoir, 2013-2016)
`imaka - a ground-layer adaptive optics system on Maunakea
We present the integration status for `imaka, the ground-layer adaptive
optics (GLAO) system on the University of Hawaii 2.2-meter telescope on
Maunakea, Hawaii. This wide-field GLAO pathfinder system exploits Maunakea's
highly confined ground layer and weak free-atmosphere to push the corrected
field of view to ~1/3 of a degree, an areal field approaching an order of
magnitude larger than any existing or planned GLAO system, with a FWHM ~ 0.33
arcseconds in the visible and near infrared. We discuss the unique design
aspects of the instrument, the driving science cases and how they impact the
system, and how we will demonstrate these cases on the sky.Comment: 9 pages, 5 figure
Wavefront correction with a ferrofluid deformable mirror: experimental results and recent developments
ABSTRACT We present the research status of a deformable mirror made of a magnetic liquid whose surface is actuated by a triangular array of small current carrying coils. We demonstrate that the mirror can correct a 11 µm low order aberrated wavefront to a residual RMS wavefront error 0.05 µm. Recent developments show that these deformable mirrors can reach a frequency response of several hundred hertz. A new method for linearizing the response of these mirrors is also presented
The Maunakea Spectroscopic Explorer Book 2018
(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is
intended as a concise reference guide to all aspects of the scientific and
technical design of MSE, for the international astronomy and engineering
communities, and related agencies. The current version is a status report of
MSE's science goals and their practical implementation, following the System
Conceptual Design Review, held in January 2018. MSE is a planned 10-m class,
wide-field, optical and near-infrared facility, designed to enable
transformative science, while filling a critical missing gap in the emerging
international network of large-scale astronomical facilities. MSE is completely
dedicated to multi-object spectroscopy of samples of between thousands and
millions of astrophysical objects. It will lead the world in this arena, due to
its unique design capabilities: it will boast a large (11.25 m) aperture and
wide (1.52 sq. degree) field of view; it will have the capabilities to observe
at a wide range of spectral resolutions, from R2500 to R40,000, with massive
multiplexing (4332 spectra per exposure, with all spectral resolutions
available at all times), and an on-target observing efficiency of more than
80%. MSE will unveil the composition and dynamics of the faint Universe and is
designed to excel at precision studies of faint astrophysical phenomena. It
will also provide critical follow-up for multi-wavelength imaging surveys, such
as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field
Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation
Very Large Array.Comment: 5 chapters, 160 pages, 107 figure
Essai d'un système d'appréciation continue des connaissances (suite)
Wittwer Jacques, Denis Michèle, Caid Michel, Brousseau G. Essai d'un système d'appréciation continue des connaissances (suite). In: Bulletin de psychologie, tome 23 n°282, 1970. pp. 458-473
Supplementary document for Wavefront control capability in a modal lens with segmented circular peripheral electrodes - 6544279.pdf
Additional measurements of amplitude responses and wavefront generations