Lucas Labadie

Laboratory and telescope demonstration of the TP3-WFS for the adaptive optics segment of AOLI

This work was supported by the Spanish Ministry of Economy under the projects AYA2011-29024, ESP2014-56869-C2-2-P, ESP2015-69020-C2-2-R and DPI2015-66458-C2-2-R, by project 15345/PI/10 from the Fundacion Seneca, by the Spanish Ministry of Education under the grant FPU12/05573, by project ST/K002368/1 from the Science and Technology Facilities Council and by ERDF funds from the European Commission. The results presented in this paper are based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Special thanks go to Lara Monteagudo and Marcos Pellejero for their timely contributions.

High spatial resolution and high contrast optical speckle imaging with FASTCAM at the ORM

In this paper, we present an original observational approach, which combines, for the first time, traditional speckle imaging with image post-processing to obtain in the optical domain diffraction-limited images with high contrast (10-5) within 0.5 to 2 arcseconds around a bright star. The post-processing step is based on wavelet filtering an has analogy with edge enhancement and high-pass filtering. Our I-band on-sky results with the 2.5-m Nordic Telescope (NOT) and the lucky imaging instrument FASTCAM show that we are able to detect L-type brown dwarf companions around a solar-type star with a contrast ▵I~12 at 2 and with no use of any coronographic capability, which greatly simplifies the instrumental and hardware approach. This object has been detected from the ground in J and H bands so far only with AO-assisted 8-10 m class telescopes (Gemini, Keck), although more recently detected with small-class telescopes in the K band. Discussing the advantage and disadvantage of the optical regime for the detection of faint intrinsic fluxes close to bright stars, we develop some perspectives for other fields, including the study of dense cores in globular clusters. To the best of our knowledge this is the first time that high contrast considerations are included in optical speckle imaging approach.

Infrared single-mode hollow conductive waveguides for stellar interferometry

This paper reports the design, realisation, and characterisation of singlemode hollow conductive waveguides for stellar interferometry. These waveguides are developed in the frame of technological developments for the ESA DARWIN mission, which aims at direct detection of exoplanets and biomarkers on them (proof of life) using nulling interferometry in the 6-20 μm spectral range. The use of singlemode waveguides is mandatory in order to meet DARWIN required performance by achieving a modal filtering better than 10-6. While there is ongoing developments of infrared dielectric fibers or integrated waveguides, both using chalcogenide glasses or silver halide compounds, this paper presents the first realisation and characterisation of singlemode hollow conductive waveguides in the DARWIN spectral range, by means of standard microelectronic and wafer bonding technologies.

Lucky imaging and adaptive optics on 10-m class telescopes: a real promise for diffraction limited imaging in the visible?

Traditionally thought as alternatives of each other, it has not been until very recently when Adaptive Optics (AO) and lucky imaging (LI) have been put to work together to achieve angular resolutions in the visible wavelengths comparable to those acquired with an ideal telescope. In this work the mutual benefits of combining fast frame selection (a.k.a. Lucky Imaging, LI) with Adaptive Optics (AO) on a 10-m class telescope are investigated by means of detailed Monte-Carlo numerical simulations. We investigate the expected image quality by looking at the Strehl Ratio (SR) at the optical R and I bands (around 650 and 800nm, respectively) and the potential of the technique to conduct high-contrast imaging. From our numerical simulations we are able to assess whether there is a net gain in the high-contrast capabilities when applying wavelet-based filtering techniques. As a test bench for what we should expect by moving on a 10-m class telescope we present recent results achieved with AO+LI at the 4-m William Herschel Telescope (WHT) by looking at the brown dwarf binary GJ569Bab.

Single-mode mid-infrared waveguides for spectro-interferometry applications

In the astrophysical context of the search for Earth-like extrasolar planets, an important research effort has been done for the realization of single-mode integrated optics devices for mid-infrared space-based interferometry. Preparatory projects like FKSI [3], where rejection of high order modes is required to a level better than 40dB, will need photonic devices that achieve modal filtering and beam combination in the mid-IR band. In this context, we present results on midinfrared planar integrated optic beam combiners characterized at LAOG using chalcogenide and silver halide materials. We show results on FTS measurements, allowing to determine the single mode spectral domain, as well as interference fringes obtained from Y-junctions realized on these materials.

Defining requirements and identifying relevant technologies in astrophotonics

Astrophotonics offers a solution to some of the problems of building instruments for the next generation of telescopes through the use of photonic devices to miniaturise and simplify instruments. It has already proved its worth in interferometry over the last decade and is now being applied to nightsky background suppression. Astrophotonics offers a radically different approach to highly-multiplexed spectroscopy to the benefit of galaxy surveys such as are required to determine the evolution of the cosmic equation of state. The Astrophotonica Europa partnership funded by the EU via OPTICON is undertaking a wide-ranging survey of the technological opportunities and their applicability to high-priority astrophysical goals of the next generation of observatories. Here we summarise some of the conclusions.

Photonics-based mid-infrared interferometry: the challenges of polychromatic operation and comparative performances

This paper is one of a three-part series of papers on photonics-based mid-IR interferometry. Here, we put the emphasis on the challenges of operating integrated optics over a broad wavelength range, a natural condition in the field of Astrophysics. We report on the recent advancements made in obtaining high interferometric contrast (> 90%) through 2-telescope combiners in the mid-IR and give an outlook on more advanced functions and 4-telescope combiners.

The calibration unit of the mid-infrared E-ELT instrument METIS

We present the preliminary design of the calibration unit of the future E-ELT instrument METIS. This independent subunit is mounted externally to the main cryostat of METIS and will function both as calibration reference for science observations, as well as verification and alignment tool during the AIT phase. In this paper, we focus on describing its preliminary layout and foreseen functionalities, based on the performance requirements defined at system level and the constraints imposed by warm IR background. We discuss the advantage of employing an integrating sphere as common radiation emitter, leading to a novel and versatile design, where the source’s spatio-spectral properties can be varied with high fidelity and repeatability. By combining only few tuneable sources and mechanisms we show how a large instrument such as METIS can be calibrated and tested, without the need of a complex cold calibration unit.

Status of the mid-IR ELT imager and spectrograph (METIS)

The Mid-Infrared ELT Imager and Spectrograph (METIS) is one of three first light instruments on the ELT. It will provide high-contrast imaging and medium resolution, slit-spectroscopy from 3 – 19um, as well as high resolution (R ~ 100,000) integral field spectroscopy from 2.9-5.3µm. All modes observe at the diffraction limit of the ELT, by means of adaptive optics, yielding angular resolutions of a few tens of milliarcseconds. The range of METIS science is broad, from Solar System objects to active galactic nuclei (AGN). We will present an update on the main science drivers for METIS: circum-stellar disks and exoplanets. The METIS project is now in full steam, approaching its preliminary design review (PDR) in 2018. In this paper we will present the current status of its optical, mechanical and thermal design as well as operational aspects. We will also discuss the challenges of building an instrument for the ELT, and the required technologies.

The warm calibration unit of METIS: optical design and principle of operation

METIS, a mid-infrared imager and spectrograph for the wavelength range 2.9–19μm (astronomical L-, M-, N- and Q-band), will be one of the first three science instruments at the European Extremely Large Telescope (E-ELT). It will provide diffraction limited imaging, coronagraphy, high resolution integral field spectroscopy and low and medium resolution slit spectroscopy. Within the international METIS consortium, the 1st Institute of Physics of the University of Cologne in Germany is responsible for the design, manufacturing, integration and qualification of the Warm Calibration Unit (WCU) of the instrument. The WCU will be a self-contained unit operating at ambient temperature outside of the voluminous METIS dewar, feeding a variety of optical calibration and alignment signals into the optical path of METIS. The functionalities of the WCU will be used for routine daily daytime calibrations after astronomical observing nights and verification of the internal alignment of METIS during assembly, integration and verification (AIV). In this contribution we present the preliminary optical design and principle of operation of the WCU in its current state of the preliminary design phase of METIS.