Abstract
The intensity variations of a laser beam by atmospheric turbulence were investigated using a He–Ne gas laser at 6328 Å with a beam diameter of about 3.5 mm and optical path lengths of 4.5 km and 14.5 km. The log-normal approximation of the intensity distribution was found to be of limited accuracy especially at high scintillation. The variation of the scintillation with the diameter of the entrance aperture of the photometer (5 mm to 80 mm) was small at the above-mentioned conditions.