PSDF OF LOG-AMPLITUDE SCINTILLATION FOR 7-MU-M BAND LASER-BEAM WITH ABSORPTION BY WATER-VAPOR

The power spectral density function (PSDF) of the log-amplitude scinti llation for an infrared laser beam was measured experimentally. To inv estigate the contribution of the absorption and the dispersion that ca use the scintillation, we chose 16 wavelengths of infrared light and o ne wavelength of visible light. It is found that the spectral density of scintillation for the infrared beam does not agree with that for th e visible beam, as predicted by Tatarskii's theory in the low-frequenc y region below 1 Hz. This disagreement between the experiment and the theory in the low-frequency region should be attributed to water vapou r absorption.