237 research outputs found
Expected performance of a self-coherent camera
No full textInternational audienceResidual wavefront errors in optical elements limit the performance of coronagraphs. To improve their efficiency, different types of devices have been proposed to correct or calibrate these errors. In this article, we study one of these techniques proposed by Baudoz et al. (2006), and called Self-Coherent Camera (SCC). The principle of this instrument is based on the lack of coherence between the stellar light and the planet that is searched for. After recalling the principle of the SCC, we simulate its performance under realistic conditions and compare it with the performance of differential imaging. To cite this article: R. Galicher, P. Baudoz, C. R. Physique 8 (2007)
Jean-François Baudoz, «Prendre sa croix». Jésus et ses disciples dans l'évangile de Marc (coll. Lire la Bible, 154). 2009
No full textvan Oyen G. Jean-François Baudoz, «Prendre sa croix». Jésus et ses disciples dans l'évangile de Marc (coll. Lire la Bible, 154). 2009. In: Revue théologique de Louvain, 41ᵉ année, fasc. 3, 2010. p. 421
Jean-François Baudoz, Les miettes de la table. Etude synoptique et socio-religieuse de Mt 15,21-28 et de Mc 7,24-30 (coll. Études bibliques, n.s., 27). 1995
No full textFocant Camille. Jean-François Baudoz, Les miettes de la table. Etude synoptique et socio-religieuse de Mt 15,21-28 et de Mc 7,24-30 (coll. Études bibliques, n.s., 27). 1995. In: Revue théologique de Louvain, 29ᵉ année, fasc. 3, 1998. p. 380
Jean-François Baudoz, Les miettes de la table. Etude synoptique et socio-religieuse de Mt 15,21-28 et de Mc 7,24-30 (coll. Études bibliques, n.s., 27). 1995
No full textFocant Camille. Jean-François Baudoz, Les miettes de la table. Etude synoptique et socio-religieuse de Mt 15,21-28 et de Mc 7,24-30 (coll. Études bibliques, n.s., 27). 1995. In: Revue théologique de Louvain, 29ᵉ année, fasc. 3, 1998. p. 380
(Invited) Point-of-Care Diagnostics with Inkjet-Printed Microchips
No full textMulti-layer inkjet printing is applied to prepare microchips that consist of up to eight three-electrode sensors comprising a carbon nanotube (CNT) working electrode, a silver/silver chloride quasireference electrode and a CNT counter electrode. Optionally, the sensors contain micro-wells to measure sample volumes as small as 50 μL. The implementation of inkjet printing allows the flexible design and highly reproducible fabrication of batches of various electrode shapes and dimensions. The usage of CNTs as standalone working electrodes results in electroanalytical sensors with reliable and superior electrochemical response compared to tested commercial carbon paste electrodes. The sensors can be used at least up to 20 times, e.g., based on an immunoassay based strategy, or in a disposable way, e.g., when measuring in complex matrices such as blood. A gold ink is applied as alternative working electrode material. The printed sensors can be used with compact multichannel potentiostats that are suitable for point-of-care diagnostics.LEP
Unravelling the performance of the SHARK-NIR Four Quadrant Phase Mask in a controlled environment
No full textSHARK-NIR is an instrument that is mounted on one of the two arms of the Large Binocular Telescope (LBT) and it concluded its commissioning phase in October 2023. The instrument is dedicated to the infrared bands Y, J and H and it is equipped with several coronagraphic masks. This work is focused on the Four Quadrant Phase Mask (FQPM). The FQPM is characterized by a four quadrant pattern with the two adjacent quadrants providing a π phase shift in order to produce destructive interference with the stellar light. The FQPM is placed at the first focal plane (coronagraphic plane) while a Lyot Stop is located at the second pupil plane of the instrument. The FQPM, when tested on sky, did not reach the expected performance. For this reason, in the laboratory of the Astronomical Observatory of Padova, a test bench has been realized to investigate the causes and the possible solutions. This test bench has been built in order to replicate exactly the optical properties and the working wavelength (λ = 1.6 μm) of the FQPM of SHARK-NIR (actually the FQPM is a spare part of SHARK-NIR) and with the additional possibility to analyze the quality of the beam on the coronagraphic plane. The controlled environment of the laboratory allowed us to test different configurations in the first pupil plane of the test bench, including: a 2-inch plane mirror, a 1-inch mirror with Tip/Tilt motors and an ALPAO 97-15 deformable mirror (DM) (the same model mounted on SHARK-NIR). The Phase Diversity (PD) technique has been used at the coronagraphic plane and at the science plane to analyze the optical quality of the beam and to tackle the problem of the Non Common Path Aberrations (NCPA). The configurations used in the laboratory, the procedures to align the FQPM and the results are reported in this work
The optical alignment of the coronagraphic masks of SHARK-NIR: Paving the way for exoplanets detection and characterization
No full textSHARK-NIR is a coronagraphic camera with spectroscopic capabilities for the Large Binocular Telescope (LBT) currently in its AIV phase, and operates in the near-infrared regime between 0.96 μm to 1.7 μm. We describe the test bench for analyzing and integrating the coronagraphic masks, by reproducing the focal plane scale, the entrance pupil dimension, and the coronagraphic techniques as similar as possible to the final assembly. The alignment procedures and code developed in Python language evaluates if these methods are accurate enough to reach the design tolerances and contrast requirements
High-contrast imaging at small separations: impact of the optical configuration of two deformable mirrors on dark holes
No full textInternational audienc
Stellar Coronography : Study & Test of a Hybrid Interfero Coronograph
No full textPublications of the Astronomical Society of the Pacific, v. 117, p. 10041011, 2005. http://dx.doi.org/10.1086/432565International audienc
High-contrast imaging in polychromatic light with the self-coherent camera
No full textContext. In the context of direct imaging of exoplanets, coronagraphs
are commonly proposed to reach the required very high contrast levels. However, wavefront
aberrations induce speckles in their focal plane and limit their performance.
Aims. An active correction of these wavefront aberrations using a
deformable mirror upstream of the coronagraph is mandatory. These aberrations need to be
calibrated and focal-plane wavefront-sensing techniques in the science channel are being
developed. One of these is the self-coherent camera, of which we present the latest
laboratory results.
Methods. We present here an enhancement of the method: we directly
minimized the complex amplitude of the speckle field in the focal plane. Laboratory tests
using a four-quadrant phase-mask coronagraph and a 32 × 32 actuator deformable mirror were
conducted in monochromatic light and in polychromatic light for different bandwidths.
Results. We obtain contrast levels in the focal plane in monochromatic
light better than 3 × 10-8 (RMS) in the 5–12 λ/D region for a
correction of both phase and amplitude aberrations. In narrow bands (10 nm) the contrast
level is 4 × 10-8 (RMS) in the same region.
Conclusions. The contrast level is currently limited by the amplitude
aberrations on the bench. We identified several improvements that can be implemented to
enhance the performance of our optical bench in monochromatic as well as in polychromatic
light
- …
