MICROSENSOR SYSTEM FOR MEASUREMENT OF ATMOSPHERIC TURBULENCE RELEVANT TO OPTICAL PROPAGATION

摘要

In order to model laser beam propagation (or optical propagation in general) through a turbulent atmosphere, one has to have knowledge about the strength of turbulence which the laser beam is encountering. The refractive index structure constant (C{sub}n) is the single most important parameter which is measure of the atmospheric turbulence strength. A microsensor system has been designed and fabricated for measurement of the turbulence parameter (C{sub}n). The instrument uses a pair of fine platinum wires (developed inhouse: wire diameter ～4-6 μm) as sensors for measurement of small (＜ 0.05 K) and fast (＞50 Hz) temperature difference (DT) fluctuations existing in the atmosphere. This paper will give the details about the design, fabrication, test and calibration of the instrument for its use to measure C{sub}n. The instrument was used for long hours to measure C{sub}n in the open atmosphere and study its diurnal variation over a 24 hour period under various atmospheric conditions covering weak, moderate and strong turbulence conditions. The results of these measurements are presented.