Experimental of atmospheric transmittances for 20P4 and 20P5 lines of HF overtone laser

In this paper, the atmospheric transmittances, the attenuation coefficient and the absorption coefficient of spectrum lines 20P4 and 20P5 of HF overtone laser are studied. The attenuation coefficient of 20P4 is 0.26～0.27km-1，and that of 20P5 is 2.24～2.28km-1. The absorption coefficient of 20P5 is 20 times bigger than that of 20P4. Simple theoretical analysis indicates that line 20P4 is the optimum line in selecting lines of HF overtone laser.