Honeywell, Inc., Corporate Research Center, Bloomington, MN
Air Force Materials Laboratory/LPO, Wright-Patterson AFB, Ohio
University of Washington, Seattle, WA
Pages: 9 Published: Jan 1979
Tunable CO2 laser calorimetry has been used to study the wavelength dependence of optical absorption at 16 different wavelengths between 9.2 and 10.85 µm in NaCl and KCl. Samples prepared on a small scale using the reactive atmosphere process (RAP) growth, as well as samples cut from large diameter ingots prepared commercially for high-power CO2 laser windows, have been investigated. A differentiation between the bulk and surface absorption has been made in several cases using long bar samples. The measured bulk absorption in the best RAP-grown NaCl crystal is intrinsic over the entire wavelength range from 9.2 to 10.85 µm, showing bulk absorption values near 9×10-4 cm-1 at 10.6 µm and 1.4×10-4 cm-1 at 9.2 µm. The best KCl shows bulk absorption values near 9×10-5 cm-1 at 10.6 µm and 4×10-5 cm-1 at 9.2 µm; these values are above the expected intrinsic limit due to residual absorption caused by the presence of at least two bulk impurities, possibly ClO3- and ClO2-.
Absorption, KCl, NaCl, 9.2 to 10.6 µm, tuneable laser calorimetry
Paper ID: STP39099S