Design of Magneto-Ellipsometer with Vortex Beam Capability*

We present a design of an optical system for measuring ellipsometric spectra in a magnetic field up to 7T and at low temperatures down to 5K. Synchrotron radiation at NSLS-II, BNL will be used as a light source. Conversion of synchrotron radiation into a source of vortex beam with a non-zero orbital angular momentum (OAM) is also developed. The optical setup will be operational in broad-band spectral range from 20 cm^-1 up to 4000 cm^-1 using Si axicone retarders producing OAM with l=+/-1. Beams with higher order OAM l=+/-1, +/-2, +/-3, +/-4 and +/-5 will be achieved with a motorized phase-shifting spiral mirror with continuous plate and staircase designs. Quantum materials will be studied using vortex beams. This work is supported by NFS-MRI grant.