ELT-HIRES the high resolution spectrograph for the ELT: phase-A design of its polarimetric unit

The Phase A study for the high-resolution spectrograph for the Extremely Large Telescope (ELT-HIRES) has been concluded in late 2017. We present the main outcome for a polarimetric light feed from the intermediate focus (IF) and a Nasmyth focus of the telescope. We conclude that the use of the IF is mandatory for high-precision spectropolarimetry. Among the description of the product tree, we present phase-A level opto-mechanical designs of the subunits, describe the observational and calibration modes, the PSF error budget, and the preliminary FEM structural and earthquake analysis. An update on the development of a ray tracing polarimetric simulator to estimate the instrumental polarization including both the telescope mirrors and the optical elements of the polarimeter is reported. Trade-off strategies and ongoing solutions in view of the Phase B are outlined too.

[1]  M. Weber,et al.  ELT-HIRES the high resolution spectrograph for the ELT: optical design studies for the polarimetric unit , 2018, Astronomical Telescopes + Instrumentation.

[2]  Maxime Boccas,et al.  Coating the 8-m Gemini telescopes with protected silver , 2004, SPIE Astronomical Telescopes + Instrumentation.

[3]  Feng Chen,et al.  Detection of circular polarization in light scattered from photosynthetic microbes , 2009, Proceedings of the National Academy of Sciences.

[4]  Enric Palle,et al.  Biosignatures as revealed by spectropolarimetry of Earthshine , 2012, Nature.

[5]  M. Genoni,et al.  ELT high resolution spectrograph: phase-A software architecture study , 2018, Astronomical Telescopes + Instrumentation.

[6]  J. Kuhn,et al.  Deriving Telescope Mueller Matrices Using Daytime Sky Polarization Observations , 2011, 1105.2615.

[7]  M. Woche,et al.  An integrated thermo-structural model to design a polarimeter for the GTC , 2016, Integrated Modeling of Complex Optomechanical Systems.

[8]  M. Woche,et al.  HIRES the high-resolution spectrograph for the E-ELT: dynamics and control of the repositioning mechanism for the E-ELT HIRES polarimeter , 2016, Astronomical Telescopes + Instrumentation.

[9]  G. Pariani,et al.  The end-to-end simulator for the E-ELT HIRES high resolution spectrograph , 2017, Optical Metrology.

[10]  Edward W. Schwieterman,et al.  DETECTION OF OCEAN GLINT AND OZONE ABSORPTION USING LCROSS EARTH OBSERVATIONS , 2014, 1405.4557.

[11]  M. Genoni,et al.  ELT-HIRES, the high resolution spectrograph for the ELT: results from the Phase A study , 2018, Astronomical Telescopes + Instrumentation.

[12]  M. Genoni,et al.  Optical and mechanical architecture for the E-ELT HIRES polarimeter , 2017, Optical Metrology.