A spectropolarimeter utilizing an Oriel MIR8000 Fourier Transform Spectrometer in the MWIR is demonstrated. The
use of the channeled spectral technique, originally developed by K. Oka, is created with the use of two AR coated
Yttrium Vanadate (YVO<sub>4</sub>) crystal retarders with a 2:1 thickness ratio. A basic mathematical model for the system is
presented, showing that the Stokes parameters are directly present in the interferogram. Theoretical results are then
compared with real data from the system, an improved model is provided to simulate the effects of absorption within the
crystal, and error between reconstructions with phase-corrected and raw interferograms is analyzed.
The birefringence of the yttrium vanadate (YVO<sub>4</sub>) crystals have been measured for the first time in the middle wavelength infrared (MWIR), <i>i.e</i>., 3-5μm. A Fourier transform spectrometer has been used in the channel spectra technique to achieve a quick measurement. Large birefringence over 0.21 has been observed in the YVO<sub>4</sub> crystals. The
transmission over 2.5-17μm of the YVO<sub>4</sub> (0.7mm thick) has been measured, which showed a transparent range up to 5.3μm. These unique features illustrate the good potential of this material for the MWIR polarization applications.