Measurement of the angular divergence and of the refraction of a laser beam in the ground layer of the atmosphere

An experimental investigation was made of the angular broadening and of the refraction of a laser beam in the ground layer of the atmosphere over a distance of 25 km between Erevan and Byurakan in Soviet Armenia. Diurnal variations in the angular divergence and the refraction were recorded. The maximum broadening of the laser beam was by a factor of 2.5, and the maximum deviations of the beam were 83 cm upward and 33 cm downward.