Rainfallinduced optical phase fluctuations in the atmosphere
Abstract
Tatarski's spectral expansion technique of optical fields is applied to calculate the phase variance, mutual coherence function, and phasedifference temporal power spectrum of an optical wave propagating through rainfall. The analysis includes the effects of a distribution of rain droplet sizes and their associated terminal velocities. The general features of the associated phase statistics are discussed, and numerical results are presented as a function of the rainfall rate. It is shown that for up to moderate rainfall conditions (i.e., approximately equal to or less than 4 mm/h) the lateral phase coherence of the wave is not significantly degraded for a propagation path of the order of a kilometer. It follows that under these conditions (moderate and less) rainfall will not pose serious limitations to coherent optical systems such as laser radars. In particular, in contrast to cleanair turbulence, raininduced phase degradations will not limit the aperature size of coherent optical systems in many practical situations. In addition, the theory presented here predicts that for lowcrosswind speed conditions the highfrequency portion of the temporalphasedifference power spectrum varies as f to the 7th power, where f is the frequency. This behavior has been seen experimentally.
 Publication:

Journal of the Optical Society of America (19171983)
 Pub Date:
 November 1983
 DOI:
 10.1364/JOSA.73.001574
 Bibcode:
 1983JOSA...73.1574Y
 Keywords:

 Atmospheric Effects;
 Atmospheric Optics;
 Coherent Light;
 Light Transmission;
 Power Spectra;
 Raindrops;
 Drop Size;
 Fluctuation Theory;
 Frequency Response;
 Particle Size Distribution;
 Phase Shift;
 Statistical Analysis;
 Lasers and Masers