Generalized spherical wave mutual coherence function

Unwrapped-phase distribution model for speckle and turbulence

A model for the unwrapped phase of a speckle field that propagates through clear air turbulence is proposed, and a formulation for the probability density function of the unwrapped phase is developed. A method is given to obtain the parameters of the unwrapped density function from parameters of the diffuse target, the laser source, and the atmosphere. Unwrapped-phase measurements at an atmospheric test site with a CO(2) laser show agreement with the model.

Covariance of the received intensity of a partially coherent laser speckle pattern in the turbulent atmosphere

A theoretical expression for the covariance of the received intensity of a partially coherent laser speckle pattern after propagation through the turbulent atmosphere is developed. It is shown that the atmospheric perturbation on a partially coherent speckle pattern can be decomposed into a coherent term and an incoherent term. The dependence of contributions of these components on the level of turbulence, vacuum speckle-contrast ratio, and detector spacing is studied in detail and the results are compared with the available experimental data.

Enhancement of backscattered intensity for a bistatic lidar operating in atmospheric turbulence

The extended Huygens-Fresnel formulation is used to calculate the enhanced backscattered intensity as a function of the off-axis receiver distance for a bistatic lidar operating in atmospheric turbulence. The result is simple and compact and allows the regime where there is significant enhancement to be readily identified. In addition, the result depends only on the logamplitude covariance, which implies that the enhancement is due to incoherent turbulence perturbation effects.

Monostatic heterodyne lidar performance: the effect of the turbulent atmosphere

The reduction in the SNR of a monostatic heterodyne lidar because of the presence of atmospheric refractive turbulence in the medium intervening between the lidar and the target was calculated. We find previous approximations made to perform the calculation, namely, independent refractive turbulence on outward bound and return paths and a quadratic form for the wave structure function, to be erroneous. An exact calculation shows that previous results overestimated signal degradation.