Design Of Multi - Functional Long - Path Turbulence Pool

Laser communication has become one of the most active research directions in the field of wireless communications with characteristics of strong confidentiality, anti-interference ability, high transmission rate and low power consumption. Realization of space laser communication is significant to grasp the initiative and promote the development of information industry quickly for our country. The laser transmission in the atmosphere is affected by atmospheric turbulence, consequently, to study the characteristics of laser transmitted in the atmosphere has become the urgent task. The outfield laser communication experiments have many shortcomings such as poor repeatability and vast resource consumption; therefore, developing indoor turbulence generator has an important practical significance and research value.Firstly, the development of indoor atmospheric turbulence generator at home and abroad is analyzed and compared in this paper. According to the principle of hot and cold wind type compound air flow, a kind of multifunctional indoor atmospheric turbulence generator with the adjustable temperature, air speed and optical path has been developed. Secondly, to achieve the purposes of laser long-distance transmission in the finite volume, an improved Herriott cell type optical long-range cell is applied into this turbulence generator. The internal temperature of turbulence cell is controlled by using proportion-integration-differentiation(PID) method. The laser transmission distance is increases by 100 m as well as the shortcomings are overcome such as hysteresis and big-inertia. Finally, the beam quality factor M2 under different temperatures and the inner scale of turbulence 0l have been measured by using the light intensity fluctuations and the angle of arrival with the help of the laser beam profiler. Moreover, the refractive index structure constant 2nC has also dynamic characteristics of turbulence are only affected by the wind speed. The experimental results are mainly consistent with theoretical model, consequently, the turbulence generator that has good feasibility and certain application prospect developed in this paper.