Infrared complex reflectance micro-spectroscopy

Far-field infrared (IR) spectroscopy techniques, such as ellipsometry and FTIR, can yield extremely accurate measurements of the optical constants (n,k) which characterize the electronic and lattice-structural degrees of freedom in novel materials and devices. However, large systematic uncertainty has plagued extensions of these techniques to small length scales. A low uncertainty embodiment would enable high quality studies of, for example, the newest correlated condensed matter systems - where typically only a small sample is available early on. Here we present mature far-field IR microscope. Most notably, an asymmetric interferometer is used to directly measure the infrared reflectance amplitude and absolute phase shift. The complex optical constants can then be extracted without the large uncertainty that arises with an amplitude measurement alone.