Final design of the wavefront sensor unit for ARGOS, the LBT's LGS facility

In this paper we present the final design of the WFS unit of LBT's ARGOS facility, that will implement a GLAO system using 3 Rayleigh pulsed beacons. The ARGOS WFS is composed of two main subunits: 1) a large dichroic window that deflects the laser beam toward the WFS and transmit the visible and near-infrared wavelength to the MOSimager LUCIFER and 2) the SH-WFS that collects the backscattered light of the 3 beacons and combines the beams on a single lenslet array and detector. The WFS unit includes Pockels cells for the range gating of the laser beams, field and pupil stabilizers to compensate for the fast jitter of the laser beams and for optical flexures and a calibration unit to check the internal alignment; this unit will be also used for closed-loop laboratory tests using a MEMS-DM.