Humidity's influence on visible region refractive index structure parameter Cn2C_n^2

In the infrared and visible bandpass, optical propagation theory conventionally assumes that humidity does not contribute to the effects of atmospheric turbulence on optical beams. While this assumption may be reasonable for dry locations, we demonstrate in this paper that there is an unequivocal effect due to the pre sence of humidity upon the strength of turbulence parameter, $C_n^2$, from data collected in the Chesapeake Bay area over 100-m length horizontal propagation paths. We describe and apply a novel technique, Hilbert Phase Analysis, to the relative humidity, temperature and $C_n^2$ data to show the contribution of the re levant climate variable to $C_n^2$ as a function of time.Comment: 16 pages, 7 figures, 2 tables, submitted to Applied Optic

Relationship of strength of turbulence to received power

Because of contributions due to reflection, the determination of the turbulence refractive index structure constant may be affected. For pure scattering from turbulence in the inertial subrange, the radar echo power can be used to calculate the refractive index structure constant. The radar power is determined by a convolution integral. If the antenna beam is swung to sufficiently large off-zenith angles ( 12.5 deg) so that a quasi-isotropic response from the tail ends of the Gaussian angular distribution can be anticipated, the evaluation of the convolution integral depends only on the known antenna pattern of the radar. This procedure, swinging the radar beam to attenuate the reflected component, may be called angular or direction filtering. The tilted antenna also may be pick up reflected components from near the zenith through the sidelobes. This can be tested by the evaluation of the correlation function. This method applies a time domain filtering of the intensity time series but needs a very careful selection of the high pass filters

Atmospheric effects on coherent laser systems

Effects of the truncation of the gaussian beam by the telescope on the signal to noise ratio were studied. Finite and infinite beams were also considered, along with the refractive index structure constant