The IR-VASE® Mark II is the only spectroscopic ellipsometer to cover the spectral range from 1.7 to 30 microns (333 to 5900 wavenumbers). The IR-VASE can determine both n and k for materials over the entire width of the spectral range without extrapolating data outside the measured range, as with a Kramers-Kronig analysis. Like other Woollam ellipsometers, the IR-VASE is perfect for thin films or bulk materials including dielectrics, semiconductors, polymers, and metals.

for additional information see

http://www.jawoollam.com/irvase_home.html