SPHERE: the exoplanet imager for the Very Large Telescope

Observations of circumstellar environments to look for the direct signal of exoplanetsand the scattered light from disks has significant instrumental implications. In the past 15 years, major developments in adaptive optics, coronagraphy, optical manufacturing, wavefront sensing and data processing, together with a consistent global system analysis have enabled a new generation of high-contrast imagers and spectrographson large ground-based telescopes with much better performance. One of the most productive is the Spectro- PolarimeticHigh contrast imager for ExoplanetsREsearch (SPHERE) designed and built for the ESO Very Large Telescope(VLT) in Chile. SPHERE includes an extreme adaptive opticssystem, a highly stable common path interface, several types of coronagraphsand three science instruments. Two of them, the Integral Field Spectrograph(IFS) and the Infra-Red Dual-band Imager and Spectrograph(IRDIS), are designed to efficiently cover the near-infrared (NIR) range in a single observation for efficient young planet search. The third one, ZIMPOL, is designed for visible (VIR) polarimetric observation to look for the reflected light of exoplanetsand the light scattered by debris disks. This suite of three science instruments enables to study circumstellar environments at unprecedented angular resolutionboth in the visible and the near-infrared. In this work, we present the complete instrument and its on-sky performance after 4 years of operations at the VLT.