ELT-HIRES the high-resolution spectrograph for the ELT: simulation results of polarimetric aberrations for the polarimetric module

ELT-HIRES (High Resolution Spectrograph for the Extremely Large Telescope) is a multifold fiber-fed spectrograph planned for the Nasmyth B focal station on ELT, with a large spectral coverage, ranging from 0.4 to 1.8 mu. It's our intention to equip it with a full Stokes polarimetric facility, feeding the UBVRI and the zYJH bands. Among the most relevant scientific targets there is the detection of life signature in the extrasolar atmospheres for Earth-like planets. The polarimetric instrument will consist of two subunits: the main one intended to be installed in the intermediate focus where the optical beam is split into the two polarized components via a double Wollaston calcite prism; the other one installed in one of the four arms of the Front End on the Nasmyth platform, in charge of the atmospheric dispersion correction, field stabilization and selection of the operating modes before the fiber injection.  This has been presented for the Phase A as the only possible design solution fulfilling the top level requirement of reaching a sensitivity of 10(-5) S/I (with S equivalent to one of the Stokes vectors), condition achievable only if the polarizers are installed in a rotationally symmetric focus.  In the present work we illustrate novel simulations of the polarized aberrations based on an integration of the structural and thermal FEM analysis within a Zemax design with the help of Matlab and Python tools.