||The GREGOR Fabry-Pérot Interferometer: A New Instrument for High-Resolution Spectropolarimetric Solar Observations
||463, 2nd ATST-EAST Workshop in Solar Physics: Magnetic Fields from the Photosphere to the Corona
||Puschmann, K. G.; Balthasar, H.; Bauer, S.-M.; Hahn, T.; Popow, E.; Seelemann, T.; Volkmer, R.; Woche, M.; Denker, C.
||Fabry-Pérot interferometers have advantages over slit spectrographs because
they allow fast narrow-band imaging and post-factum image reconstruction of
the retrieved data. Temperature, plasma velocity, and magnetic field maps
can be derived from inversions of spectral lines, thus, advancing our
understanding of the dynamic Sun and its magnetic fields at
the smallest spatial scales. The GREGOR Fabry-Pérot Interferometer (GFPI) is
one of two first-light instruments of the 1.5-meter GREGOR solar telescope,
which is currently being commissioned at the Observatorio del Teide, Tenerife,
Spain. The GFPI operates close to the diffraction limit of GREGOR, thus,
providing access to fine structures as small as 60 km on the solar surface. The
field-of-view of 52″×40″ is sufficiently large to cover
significant area fraction of active regions.
The GFPI is a tuneable dual-etalon system
in a collimated mounting. Equipped with a full-Stokes polarimeter, it records
spectropolarimetric data with a spectral resolution of R ≈ 250,000 over
the wavelength range from 530–860 nm. Large-format, high-cadence CCD detectors
with powerful computer hard- and software facilitate scanning of spectral lines
in time spans corresponding to the evolution time-scale of solar features. We
present the main characteristics of the GFPI including the latest developments
in software, mechanical mounts, and optics.