1. A method for characterizing intensity fluctuations as a measure of atmospheric turbulence of free space optical communication of a laser beam, said laser beam being transmitted from a transmitter to a receiver having an image plane, said method comprising the steps of: capturing, by a detector, an image that results when said laser beam is incident on said image plane; recording, by a recorder, the captured image; and performing, by a processor: A) preprocessing said captured recorded image from said image plane to limit a number of pixels of said captured recorded image, said preprocessing step resulting in an enhanced preprocessed image; B) counting the number of laser speckles at said enhanced preprocessed image from said step A); and, C) finding Fried's parameter r 0 , using the result of said step B), as an indicator of the intensity fluctuations, for measurement of said atmospheric turbulence.