Overview of LBTI: a multipurpose facility for high spatial resolution observations

Abstract

The Large Binocular Telescope Interferometer (LBTI) is a high spatial resolution instrument developed for coherent imaging and nulling interferometry using the 14.4 m baseline of the 2×8.4 m LBT. The unique telescope design, comprising of the dual apertures on a common elevation-azimuth mount, enables a broad use of observing modes. The full system is comprised of dual adaptive optics systems, a near-infrared phasing camera, a 1-5 µm camera (called LMIRCam), and an 8-13 µm camera (called NOMIC). The key program for LBTI is the Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS), a survey using nulling interferometry to constrain the typical brightness from exozodiacal dust around nearby stars. Additional observations focus on the detection and characterization of giant planets in the thermal infrared, high spatial resolution imaging of complex scenes such as Jupiter's moon, Io, planets forming in transition disks, and the structure of active Galactic Nuclei (AGN). Several instrumental upgrades are currently underway to improve and expand the capabilities of LBTI. These include: Improving the performance and limiting magnitude of the parallel adaptive optics systems; quadrupling the field of view of LMIRcam (increasing to 20"x20"); adding an integral field spectrometry mode; and implementing a new algorithm for path length correction that accounts for dispersion due to atmospheric water vapor. We present the current architecture and performance of LBTI, as well as an overview of the upgrades.

STIM map: detection map for exoplanets imaging beyond asymptotic Gaussian residual speckle noise

“…Coronagraph devices are then used to increase the dynamic range by removing the coherent part of the starlight which is hiding the faint circumstellar signals (Guyon et al 2006). With dedicated instruments such as VLT/SPHERE (Beuzit et al 2008), Gemini/GPI , KecK/NIRC2 (McLean & Chaffee 2000), Subaru/SCeXAO (Jovanovic et al 2015) or LBTI/LMIRCam (Hinz et al 2016), a typical contrast of 10 −4 is obtained at a separation of 0.5 arcsec. However, residual aberrations induce the presence of speckles in the images, which are of the same angular size as a point source and are often brighter than the exoplanets signal.…”

Enabling discoveries: a review of 30 years of advanced technologies and instrumentation at the National Science Foundation

“…113,114 Interferometry was further developed for astronomy in the late 1970s and 1980s, which led to instruments such as the Sydney University Stellar Interferometer 115 and the Mark III interferometer. [116][117][118][119] The current generation of interferometers includes the Navy Precision Optical Interferometer (NPOI), 120 the Palomar Testbed Interferometer (decommissioned), 121 the Center for High Angular Resolution Astronomy array (CHARA), 122 the (decommissioned) Keck Interferometer, 123 the Magdalena Ridge Optical Interferometer (MROI; not yet operational), 124 the Large Binocular Telescope Interferometer (LBTI), 125 and especially the Very Large Telescope Interferometer, VLTI, experiment GRAVITY. 126,127 GRAVITY is supported by the European Southern Observatory, whereas the major US-based initiatives include LBTI, NPOI, MROI, and CHARA.…”

Minimizing the Polarization Leakage of Geometric-phase Coronagraphs with Multiple Grating Pattern Combinations

“…In addition to being able to spectrally characterize exoplanets, other advantages that broadband coronagraphs offer include increased observing flexibility and efficiency, diagnostics for wavelength-dependent instrument calibration, and spectral differential methods (Sparks & Ford, 2002;Snellen et al, 2015). Even current ground-based high-contrast imaging systems could benefit from an enhanced broadband coronagraph implementation (provided sufficient wavefront control), as they all have a coronagraph in the common path and split up to different wavelength channels afterwards (Macintosh et al, 2014;Lozi et al, 2018;Hinz et al, 2016;Males et al, 2018;Beuzit et al, 2019). Many coronagraphs installed in these systems are optimized for a single observing band, and perform suboptimal when used in a broad spectral band or at different wavelengths.…”