Measured statistics of laser beam scintillation in strong refractive turbulence relevant to eye safety.

The time series of irradiance from a diverged He-Ne laser were measured using receiver aperture sizes that simulate the day-adapted and night-adapted human pupil. The data are within the saturation-of-scintillation regime wherein the irradiance variance decreases with further increases of propagation distance and refractive turbulence strength. Irradiance probability distributions, as well as the joint statistics of irradiance and duration of large irradiance values, are presented. The ocular hazard contributed by scintillation is found to decrease with increases of range and/or refractive turbulence strength; this effect is independent of the decrease of mean irradiance associated with such increases of range and refractive turbulence strength.