Research On Testing Technology Of Atmospheric Coherence Length Based On DIMM

When the laser propagating in turbulent atmosphere, the random fluctuation of the atmospheric refractive index make the amplitude and phase of the laser signal fluctuating randomly, so that it can cause the speckle and the flicker phenomenon of the signal at receiving end, even break the facula completely. These effects seriously restrict the application of atmospheric transmission project of laser. Therefore, it is very important to analyze and measure the influence of atmospheric turbulence on laser engineering.This paper details the DIMM present situation in China and abroad, summarize the technical parameters of the typical instrument. Sketch the mechanism of turbulent. Discusse the optical properties of atmospheric turbulence from three aspects: the refractive index structure constant, the phase perturbation and arrival angle; Piont out the important significance of the atmospheric coherence length as the only parameter that can describe the turbulence intensity comprehensively; Analyze the advantages of DIMM that simple operation, low cost and high accuracy by compared with the other turbulence intensity measurement method. Provide details on DIMM measurement principle. Determine the design scheme and the important parameters. Complete structure design, finish assembling and adjusting.The atmospheric coherence length curve is obtained after the whole night observing experiments in the field. In the process of measurement, the equipment has high tracking accuracy, good stability, and no need for human intervention.The results show that the variation trend conforms to the atmospheric turbulence intensity changing characteristics during night. The feasibility of the DIMM system to measure atmospheric turbulence intensity is proved.