Very cool wheels for a very large telescope
- Astronomy
- Astrophysics (IPA)
The Laboratory for Astronomical Instrumentation at ETH Zurich has shipped its first cryogenic wheels that were developed for the new infrared instrument ERIS on the Very Large Telescope (VLT) of the European Southern Observatory (ESO). These mechanisms will hold various filters and masks that provide unique capabilities for direct imaging and characterization of exoplanets.
The Laboratory for Astronomical Instrumentation — part of the Star and Planet Formation group of the Institute of Particle Physics and Astrophysics — is involved in the development of the Enhanced Resolution Imager and Spectrograph (ERIS) instrument, a next-generation facility for the Very Large Telescope of ESO. In collaboration with the Max Planck Institute for Extraterrestrial Physics (MPE) and the UK Astronomy Technology Center (ATC), the group is responsible for the development of two cryogenic mechanisms that will hold various filters, coronagraphs and masks with a focus on high-contrast as well as direct imaging and characterization of exoplanets.
The two wheels, the Aperture Wheel and the Pupil and Filter Wheel, will operate at 70 K (–203˚C) with a very high mechanical accuracy of a few of microns.
The wheels were designed and manufactured within the Department of Physics in collaboration with the Engineering Office and the Mechanical Workshop. The two wheels were tested at cryogenic conditions in the Laboratory for Astronomical Instrumentation, using a custom-made cryostat for operations at 70 K and lower. The cryostat provides a window that enables optical measurements of the wheels at these temperatures, which was essential for the verification of the requirements. After delivery of the mechanisms to the UK ATC in Edinburgh, they will be integrated onto the ERIS/NIX camera.
ERIS is a 1–5 μm instrument to be installed at the Cassegrain focus of the VLT UT4 for 'first light' in 2020. ERIS will benefit from the new Adaptive Optics Facility (AOF), which includes a deformable secondary mirror (DSM) to deliver high-Strehl imaging performance at the instrument focal plane. The instrument will provide both imaging and spectroscopic capabilities, and will be able to suppress the light of the star in different wavelength bands, possibly revealing much fainter companions. This allows for the detection and atmospheric characterization of gas giant extrasolar planets.
