Single-loop interferometer for minimal ellipsometry
  We present a simple polarizing Mach-Zehnder interferometer that can be used for optimal minimal ellipsometry: Only four intensities are measured to determine the three Stokes parameters, and an optimal choice for the four polarization projections can be achieved for any sufficiently small wavelength range of interest. 
Berthold-Georg Englert, Tin Kah Ming, Goh Choon Guan, Ng Hui Khoon