Lessons learned from VISIR

VISIR is the VLT mid-infrared (mid-IR) Imager and Spectrometer. Since 2004, it provides data at high spatial and spectral resolutions in the N (8-13 μm) and Q (16-24 μm) atmospheric windows. VISIR observations have provided unique constraints on targets such as central regions of nearby galaxies, or protoplanetary disks. We review here VISIR Imager and Spectrometer characteristics, emphasizing on some current limitations because of various undesirable effects. Its successor on an ELT will provide data with a unique sharpness (0.05") and sensitivity (35 μJy source detectable in 1 hour at 10 σ level), thus allowing a characterization of exoplanetary disks and inner exoplanets with an unprecedent precision. At the light of VISIR experience, we discuss how the lessons learned from VISIR can be turned to good account for designing and operating the future mid-IR instrument on the European ELT.