Infrared wavelength modulation spectroscopy of some optical materials

Infrared wavelength modulation techniques were developed and used to investigate the low-level absorption of some optical materials such as alkali halides and alkaline earth fluorides. The results reveal rich absorption structures which enable an identification of some of the surface and bulk impurities of these materials. Those impurities are principal sources of optical absorption which limit the expected transparency of these materials in the spectral region studied (2.5–12 μm).