31 research outputs found
The MAORY laser guide star wavefront sensor: design status
MAORY will be the multi-adaptive optics module feeding the high resolution camera and spectrograph MICADO at the Extremely Large Telescope (ELT) first light. In order to ensure high and homogeneous image quality over the MICADO field of view and high sky coverage, the baseline is to operate wavefront sensing using six Sodium Laser Guide Stars. The Laser Guide Star Wavefront Sensor (LGS WFS) is the MAORY sub-system devoted to real-time measurement of the high order wavefront distortions. In this paper we describe the MAORY LGS WFS current design, including opto-mechanics, trade-offs and possible future improvements
The GRAVITY+ Project: Towards All-sky, Faint-Science, High-Contrast Near-Infrared Interferometry at the VLTI
The GRAVITY instrument has been revolutionary for near-infrared
interferometry by pushing sensitivity and precision to previously unknown
limits. With the upgrade of GRAVITY and the Very Large Telescope Interferometer
(VLTI) in GRAVITY+, these limits will be pushed even further, with vastly
improved sky coverage, as well as faint-science and high-contrast capabilities.
This upgrade includes the implementation of wide-field off-axis
fringe-tracking, new adaptive optics systems on all Unit Telescopes, and laser
guide stars in an upgraded facility. GRAVITY+ will open up the sky to the
measurement of black hole masses across cosmic time in hundreds of active
galactic nuclei, use the faint stars in the Galactic centre to probe General
Relativity, and enable the characterisation of dozens of young exoplanets to
study their formation, bearing the promise of another scientific revolution to
come at the VLTI.Comment: Published in the ESO Messenge
The MAORY first-light adaptive optics module for E-ELT
The MAORY adaptive optics module is part of the first light instrumentation suite for the E-ELT. The MAORY project phase B is going to start soon. This paper contains a system-level overview of the current instrument design
MAORY for ELT: preliminary design overview
MAORY is one of the approved instruments for the European Extremely Large Telescope. It is an adaptive optics module, enabling high-angular resolution observations in the near infrared by real-time compensation of the wavefront distortions due to atmospheric turbulence and other disturbances such as wind action on the telescope. An overview of the instrument design is given in this paper
Characterizing the attenuation of coaxial and rectangular microwave-frequency waveguides at cryogenic temperatures
Abstract Low-loss waveguides are required for quantum communication at distances beyond the chip-scale for any low-temperature solid-state implementation of quantum information processors. We measure and analyze the attenuation constant of commercially available microwave-frequency waveguides down to millikelvin temperatures and single photon levels. More specifically, we characterize the frequency-dependent loss of a range of coaxial and rectangular microwave waveguides down to 0.005 dB / m 0.005\ \mbox{dB}/\mbox{m} using a resonant-cavity technique. We study the loss tangent and relative permittivity of commonly used dielectric waveguide materials by measurements of the internal quality factors and their comparison with established loss models. The results of our characterization are relevant for accurately predicting the signal levels at the input of cryogenic devices, for reducing the loss in any detection chain, and for estimating the heat load induced by signal dissipation in cryogenic systems
SHADOWS: a spectro-gonio radiometer for bidirectional reflectance studies of dark meteorites and terrestrial analogs: design, calibrations, and performances on challenging surfaces
International audienceWe have developed a new spectro-gonio radiometer, SHADOWS, to study in the laboratory the bidirectional reflectance distribution function of dark and precious samples. The instrument operates over a wide spectral range from the visible to the near-infrared (350-5000 nm) and is installed in a cold room to operate at a temperature as low as â20°C. The high flux monochromatic beam is focused on the sample, resulting in an illumination spot of about 5.2 mm in diameter. The reflected light is measured by two detectors with high sensitivity (down to 0.005% in reflectance) and absolute accuracy of 1%. The illumination and observations angles, including azimuth, can be varied over wide ranges. This paper presents the scientific and technical constraints of the spectro-gonio radiometer, its design and additional capabilities, as well as the performances and limitations of the instrument
Testing light concentrators prototypes for the Cherenkov Telescope Array
International audienceWith more than 30 Medium-Size Telescopes (MST) located in both North and South hemispheres, the Cherenkov Telescope Array (CTA) shall be the largest cosmic gamma ray detector ever built. Each MST focal plane consists in an array of some 1800 photomultipliers equipped with their own light concentrating optics in order to maximizing the amount of Cherenkov radiation collected by the telescope and to block stray light originating from ground environment. Within the CTA Consortium, the Institut de PlanĂ©tologie et dâAstrophysique de Grenoble (IPAG) is in charge of designing, subcontracting the realization to industry, and testing the MST light concentrators. Two different optical solutions were pre-selected, respectively based on CPCs (Winston cones) and non-imaging concentrating lenses. Prototypes were manufactured by different industrial companies and tested in our laboratory on a test bench specifically built for the project. After shortly describing both optical designs, this communication is essentially focused at experimental results. Each type of concentrator has been submitted to extensive performance measurements, including radiometric efficiency at different wavelengths, rejection curves, and qualitative shape error test. The final selected concentrator is the CPC, although non-imaging lenses exhibit interesting properties in terms of radiometric performance