ERIS (Enhanced Resolution Imager and Spectrograph) is an instrument for diffraction limited imaging, coronography and spectroscopy on the Cassegrain focus of VLT UT4 in the 1 to 5µm spectral range to be commissioned early 2020. It will combine the existing integral field spectrograph SPIFFI with a new near infrared camera and a wavefront sensor module for the ESO adaptive optics facility.

ESO decided to upgrade the VLT UT4 by an adaptive optics (AO) facility which includes a deformable secondary mirror and four laser guide stars. At the time when this facility will be installed, the existing instruments SINFONI and NACO become obsolete. Since NACO is reaching the end of its lifetime, it will be decommissioned, and its focal station will be occupied by the new ESO instrument MUSE. However, the high spatial resolution imaging and spectroscopy modes of NACO and SINFONI are indispensable for the VLT. Therefore ESO decided to build ERIS which makes use of the new AO facility and is composed of four main components:

  • an upgraded version of SPIFFI with better throughput and higher spectral resolution
  • a near infrared camera called NIX to provide imaging in J, H, K, L, M bands as well as high contrast imaging in L and M bands
  • a wavefront module that uses the AOF and provides much higher strehl than currently available
  • a calibration unit for spectral, spatial and photometric calibration of all sub-systems

The ERIS instrument thus provides similar functionality compared to NACO and SINFONI but significantly better performance, to last beyond 2030.

MPE has been involved in the project since the ERIS phase A study. End of 2014 a consortium has been formed under leadership of MPE to start the preliminary design phase of ERIS. The work towards the preliminary design review in Feb 2016 resulted in the following instrument concept presented in the figures below:

The figure on the left illustrates the optical concept of the instrument. The view of the CAD model in the right figure shows an overview of the mechanical design status at the time of the preliminary design review.

The responsibilities within the ERIS project and sub-systems are distributed among the consortium partners:

  • Principle Investigator (R. Davies), project management, system engineering: MPE
  • SPIFFI upgrade to SPIFFIER: MPE
  • Central mechanical structure, system electronics and IR detectors: MPE
  • NIX camera system: UK Astronomy Technology Centre in Edinburgh (ATC)
  • NIX filter, pupil and aperture wheels including all filters and masks: ETH-Zürich, NOVA (Leiden)
  • Adaptive optics and warm optics: INAF-Arcetri
  • Calibration unit: INAF-Teramo
  • Instrument control software: INAF-Padua (lead) in collaboration with ATC and MPE
  • Pipeline software: MPE (SPIFFIER), ATC (NIX)
  • Wavefront sensor cameras, adaptive optics real time computer, detector procurement and testing: ESO

Major schedule milestones for the ERIS project:

  • End 2014: Formation of consortium
  • Feb 2016: Preliminary design review
  • Spring 2017: Final design review
  • Mid to end 2019: Integrated system tests at MPE
  • Jan 2020: Shipment of ERIS to Paranal
  • Spring 2020: Commissioning

The ERIS project at ESO: ERIS at ESO

Picture credits: 1: ESO; 2, 3 : MPE;

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