High resolution millimeter wave SAR interferometry

High resolution millimeter wave synthetic aperture radar (SAR) interferometry is presented using the MEMPHIS multi-baseline InSAR system. A complete processing chain is used to generate digital elevation models starting from the radar raw data. A deeper focus is laid on the phase unwrapping step, which is achieved using the multi-baseline properties of the system. In November 2006, an experiment was realized including two test sites in Switzerland; the actual results are presented and discussed

Processing of MEMPHIS millimeter wave multi-baseline InSAR data

This paper presents a processing method for multi-baseline interferometric data acquired with the MEMPHIS airborne sensor. The processing method ingests the SAR raw data from each receiver and extends up to the generation of digital elevation models (DEMs). Critical steps include the correction of the azimuth phase undulations, the multi- baseline processing and the phase-to-DEM conversion. Methods for resolving the various hurdles were adapted to the MEMPHIS sensor and are presented here. The results obtained for a data take over a test site near Zurich, Switzerland are shown; these results are in a good agreement with comparable LIDAR products

Processing, geocoding and mosaicking of MiSAR data

EADS MiSAR ist ein Miniatur FM-CW Ka-Band SAR-System, entwickelt für UAVPlattformen wie dem Deutschen LUNA-System. MiSAR kann Echtzeit ("Video-ähnliche") SAR-Bilder liefern. In diesem Modus werden SAR-Bilder mit einer Rate von ~1 Hz erzeugt, mit einem Überlappungsbereich von ~90% zwischen aufeinander folgenden Bildern. Im vorliegenden Artikel wird ein Ansatz präsentiert, wie aufeinander foldende Bilder sequenziell, mit Hilfe von Flugzeug-Navigationsdaten, einem Geländemodell sowie den Range-Doppler Gleichungen geokodiert werden. Das Resultat der anschliessenden Mosaikierung ist ein Bildstreifen beliebiger Länge. Um eine optimale Grundlage für Geokodierung bereitzustellen wurde eigens ein neues, SPECAN-basiertes Fokussierungsverfahren implementiert, welches aus den "range-komprimierten" Daten die benötigten Einzelbilder samt geometrischen Parametern liefert. Die Ergebnisse zeigen eine gute Fokussierungsqualität sowie eine sehr hohe Geokodierungs-Genauigkeit. Die Implementierung erlaubt eine Geokodierung/Mosaikierung auf beliebige geodätische und kartographische Referenzsysteme

Realizing a Deterministic Source of Multipartite-Entangled Photonic Qubits

Sources of entangled electromagnetic radiation are a cornerstone in quantum information processing and offer unique opportunities for the study of quantum many-body physics in a controlled experimental setting. While multi-mode entangled states of radiation have been generated in various platforms, all previous experiments are either probabilistic or restricted to generate specific types of states with a moderate entanglement length. Here, we demonstrate the fully deterministic generation of purely photonic entangled states such as the cluster, GHZ, and W state by sequentially emitting microwave photons from a controlled auxiliary system into a waveguide. We tomographically reconstruct the entire quantum many-body state for up to $N=4$ photonic modes and infer the quantum state for even larger $N$ from process tomography. We estimate that localizable entanglement persists over a distance of approximately ten photonic qubits, outperforming any previous deterministic scheme

Shadows and spirals in the protoplanetary disk HD 100453

Understanding the diversity of planets requires to study the morphology and the physical conditions in the protoplanetary disks in which they form. We observed and spatially resolved the disk around the ~10 Myr old protoplanetary disk HD 100453 in polarized scattered light with SPHERE/VLT at optical and near-infrared wavelengths, reaching an angular resolution of ~0.02", and an inner working angle of ~0.09". We detect polarized scattered light up to ~0.42" (~48 au) and detect a cavity, a rim with azimuthal brightness variations at an inclination of 38 degrees, two shadows and two symmetric spiral arms. The spiral arms originate near the location of the shadows, close to the semi major axis. We detect a faint spiral-like feature in the SW that can be interpreted as the scattering surface of the bottom side of the disk, if the disk is tidally truncated by the M-dwarf companion currently seen at a projected distance of ~119 au. We construct a radiative transfer model that accounts for the main characteristics of the features with an inner and outer disk misaligned by ~72 degrees. The azimuthal brightness variations along the rim are well reproduced with the scattering phase function of the model. While spirals can be triggered by the tidal interaction with the companion, the close proximity of the spirals to the shadows suggests that the shadows could also play a role. The change in stellar illumination along the rim, induces an azimuthal variation of the scale height that can contribute to the brightness variations. Dark regions in polarized images of transition disks are now detected in a handful of disks and often interpreted as shadows due to a misaligned inner disk. The origin of such a misalignment in HD 100453, and of the spirals, is unclear, and might be due to a yet-undetected massive companion inside the cavity, and on an inclined orbit.Comment: A&A, accepte

PIONIER: a visitor instrument for the VLTI

PIONIER is a 4-telescope visitor instrument for the VLTI, planned to see its first fringes in 2010. It combines four ATs or four UTs using a pairwise ABCD integrated optics combiner that can also be used in scanning mode. It provides low spectral resolution in H and K band. PIONIER is designed for imaging with a specific emphasis on fast fringe recording to allow closure-phases and visibilities to be precisely measured. In this work we provide the detailed description of the instrument and present its updated status.Comment: Proceedings of SPIE conference Optical and Infrared Interferometry II (Conference 7734) San Diego 201

Post conjunction detection of β\beta Pictoris b with VLT/SPHERE

With an orbital distance comparable to that of Saturn in the solar system, \bpic b is the closest (semi-major axis $\simeq$\,9\,au) exoplanet that has been imaged to orbit a star. Thus it offers unique opportunities for detailed studies of its orbital, physical, and atmospheric properties, and of disk-planet interactions. With the exception of the discovery observations in 2003 with NaCo at the Very Large Telescope (VLT), all following astrometric measurements relative to \bpic have been obtained in the southwestern part of the orbit, which severely limits the determination of the planet's orbital parameters. We aimed at further constraining \bpic b orbital properties using more data, and, in particular, data taken in the northeastern part of the orbit. We used SPHERE at the VLT to precisely monitor the orbital motion of beta \bpic b since first light of the instrument in 2014. We were able to monitor the planet until November 2016, when its angular separation became too small (125 mas, i.e., 1.6\,au) and prevented further detection. We redetected \bpic b on the northeast side of the disk at a separation of 139\,mas and a PA of 30$^{\circ}$ in September 2018. The planetary orbit is now well constrained. With a semi-major axis (sma) of $a = 9.0 \pm 0.5$ au (1 $\sigma$), it definitely excludes previously reported possible long orbital periods, and excludes \bpic b as the origin of photometric variations that took place in 1981. We also refine the eccentricity and inclination of the planet. From an instrumental point of view, these data demonstrate that it is possible to detect, if they exist, young massive Jupiters that orbit at less than 2 au from a star that is 20 pc away.Comment: accepted by A&