By coupling an infrared diode laser to a conventional infrared microscope, one achieves resolution approaching the diffraction limit while enabling rapid data collection. This technique is demonstrated with the use of a layered polymer sample that has been contaminated by migration of a volatile additive from an exogenous source. The distribution of this additive in the layered structure is shown to correlate with specific layers and reveals a concentration gradient suggesting a diffusive mechanism of additive migration parallel to the layered structure.
James A. Bailey, R. Brian Dyer, Darla K. Graff, and Jon R. Schoonover, "High Spatial Resolution for IR Imaging Using an IR Diode Laser," Appl. Spectrosc. 54, 159-163 (2000)