Atmospheric transmittance measurements of CO2 and near-IR laser radiation over 8.6 km

摘要

A long range laser transmissometer to measure atmospheric extinction at different laser wavelengths simultaneously from near to thermal infrared (1.06 $mu@m and 10.6 $mu@m) was designed, constructed, and operated under different atmospheric conditions over a distance of 8.6 km in hilly terrain near Tuebingen, Germany. Beam extinction was obtained by measuring the ratio of the total transmitted laser radiation to the total received radiation as collected by a mirror and focused onto a pyroelectrical detector array. Measured values of Nd:YAG and CO$-2$/ laser extinction are compared with model predictions (FASCODE 3P) based on simultaneously measured meteorological data as model input parameters. The agreement between measurement and calculation is better than expected. The corresponding extinction coefficients cover the range 0.05 km$+$MIN@1$/ to 0.17 km$+$MIN@1$/ for Nd:YAG laser radiation and 0.07 km$+$MIN@1$/ to 0.25 km$+$MIN@1$/ for CO$-2$/ laser radiation.