Modeling microphysical influences on optical turbulence

摘要

Optical turbulence is important because it can significantly degrade the performance of electro-optical and infrared sensors, such as free-space laser communications and infrared imaging systems. Changes in the refractive index of air along the transmission path of an optical system in free space can influence traveling light waves temporally and spatially causing blurring, scintillation, and bean wander. If left uncompensated, these effects could cause fades and surges in transmitted signals and result in high bit errors in communicated data. An earlier paper discussed the growing need for increasingly accurate and reliable numerical models to predict optical turbulence conditions, especially in complex (non-uniform) signal propagation environments. Hence, we present a finite-difference computer model to predict the microphysical (microclimate) influences on optical turbulence (C_n~2) around the ARL A_LOT Facility and its surroundings, e.g., forests and multiple buildings. Our multi-dimensional prototypical model begins to address optical turbulence conditions along more complex optical lines-of-site and account for inhomogeneities in C_n~2 brought about by horizontal changes in landscape, wind flow, temperature, and humidity. We anticipate that this kind of computational research will be an important vehicle for investigating C_n~2 and related laser-optic propagation effects in complex areas.