  Paramagnetic Faraday rotation is a powerful technique for atom sensing widely
used in quantum non-demolition measurements, fundamental symmetry tests, and
other precision measurements. We demonstrate the use of a multi-pass optical
cell for Faraday rotation spectroscopy and observe polarization rotation in
excess of 100 radians from spin-polarized Rb vapor. Unlike optical cavities,
multi-pass cells have a deterministic number of light passes and can be used to
measure large optical rotations. We also observe a 10-fold suppression of
transverse spin relaxation when Rb atoms are placed in a coherent superposition
state immune to spin-exchange collisions.
