Calculated Absorption Coefficients for Lo-Vibrational CO Laser Frequencies

CO lasers operating on the lower vibrational bands 4-3, 3-2, 2-1, 1- 0 will suffer less atmospheric absorption loss than higher band CO lasers due mainly to operation further from the 6.3 micrometer water vapor band. The AFCRL absorption line-data tape is used to compute the CO, CO2, and H2O absorption coefficients for the mid-latitude summer model and 115 laser frequencies of the 5-4 to 1-0 CO bands for altitudes of sea level, 3 km, and 6 km. It is found that at sea level 17 of these lines have a lower absorption coefficient than the P20 CO2 laser line for the same atmospheric model. The calculated results are being used to guide the selection of lines to be investigated in a laboratory measurement program utilizing either a CO laser or PbSSe laser diodes having output in the same frequency range as the CO laser.