In the context of interferometric integral field spectroscopy at the LBT, we have investigated the physics of coupling
light from a double pupil into optical fibers. Previous fiber-fed astronomical instruments solved the problem of coupling
light from a single dish into single- and multi-mode fibers. However, this is an unexplored territory for a telescope
configuration such as the LBT. We have investigated the coupling of the telescope's double pupil to optical fibers in
detail, and present results from numerical simulations and preliminary measurements from an experimental setup.
We present a feasible design concept and the science drivers for the proposed near-infrared interferometric integral field
spectrograph at the LBT. Combining interferometric resolution with an integral field spectrograph is a very promising
instrument concept for detailed studies down to below 10 mas angular resolution in the NIR. If approved, the instrument
will become an extension to the LINC-NIRVANA instrument, which is under construction.
In this contribution an opto-mechanical design concept has been studied in detail: that places the integral field unit into
an existing empty compartment within the LINC hardware. Several optical and mechanical challenges have been
successfully mastered, among them:
- the limitation of the achievable angular resolution due to the parallactic angle rotation versus the LBT baseline,
- the anamorphic magnification required by the LBT optics design to optimize the detector information content, and
- integrating the IFU into the existing LINC cryostat without interfering with the existing optics and mechanics.
The science program spans from solar system studies and spectroscopy of exoplanets to the black hole dynamics in the
center of our and other galaxies.
We present two design concepts and the science drivers of a proposed near-infrared interferometric integral field
spectrograph for the LBT. This instrument will expand the capabilities of the currently-under-construction
interferometric camera LINC-NIRVANA with spectroscopy by means of an integral field unit (IFU) located inside the
LINC cryostat. Two instrument concepts have been studied in detail: a microlens array IFU with a spectrograph built
entirely inside LINC (the LIINUS approach), and a lenslet+fibers IFU feeding an external spectrograph (the SERPIL
approach). In both cases, the instrument incorporates imaging interferometry with integral field spectroscopy, an ideal
combination for detailed studies of astronomical objects down to below 10mas angular resolution in the near-infrared.
The scientific applications range from solar system studies and spectroscopy of exoplanets to the dynamics of stars and
gas in the central regions of the Milky Way and other nearby galaxies.
LIINUS/SERPIL is a design study to augment LBTs interferometric beam combiner camera LINC-NIRVANA with imaging spectroscopy. The FWHM of the interferometric main beam at 1.5 micron will be about 10 mas, offering unique imaging and spectroscopic capabilities well beyond the angular resolution of current 8-10m telescopes. At 10 mas angular scale, e.g., one resolution element at the distance of the Galactic Center corresponds to the average diameter of the Pluto orbit (79 AU), hence the size of the solar system. Taking advantage of the LBT interferometric beam with an equivalent maximum diameter of 23 m, LIINUS/SERPIL is an ideal precursor instrument for (imaging) spectrographs at extremely large full aperture telescopes. LIINUS/SERPIL will be built upon the LINC-NIRVANA hardware and LIINUS/SERPIL could potentially be developed on a rather short timescale. The study investigates several concepts for the optical as well as for the mechanical design. We present the scientific promises of such an instrument together with the current status of the design study.