First laboratory results of SPHERE/IRDIS dual-band imaging and long slit spectroscopy modes

Abstract

IRDIS is one of the science sub-systems of VLT/SPHERE dedicated to the detection and characterization of giant exoplanets at large orbital radii with high-contrast direct imaging. It offers a unique set of observational modes including dual-band imaging (DBI) with very low differential aberrations, and long slit spectroscopy (LSS) coupled with a classical Lyot coronograph that will be used to obtain spectra at low (R = ~50) and medium (R = ~500) resolution. During the past year, IRDIS has been integrated and tested in laboratory in a standalone configuration, and it has recently been integrated on the full SPHERE bench including the calibration unit, the common path optics and the extreme AO system. We present the first analysis of data obtained during laboratory tests of IRDIS in the DBI mode, both in standalone and with the full SPHERE bench, but without simulated seeing and AO correction. We show the first performance estimates of spectral differential imaging with IRDIS in H-band, which is used to attenuate the speckle noise induced by the instrumental aberrations. Similarly, for the LSS mode we present the first application of the spectral deconvolution data analysis method to attenuate the speckle noise on IRDIS data. Finally we compare these results to simulations that were performed during the development phase of the instrument.