Extending The Range Of Validity Of Optical Scintillometer Measurements

Measurements of the level of turbulence Cn2 have been successfully performed with the optical scintillometer. The success of this instrument is based on the observed fact that the variance of aperture-averaged scintillation is described by weak scattering theory even for conditions under which strong scintillation is observed for small apertures. However, for sufficiently long propagation paths the aperture-averaged variance is affected by strong scattering. The effects of strong scattering are calculated theoretically and compared to experiment. The physics of this regime are discussed and the important parameters investigated in order to extend the range of validity of optical scintillometer measurements.